Six Months Industrial Training Report
At
TATA TELESERVICES LTD.
Submitted in partial fulfilment of the requirements for the award of degree of
BACHELOR OF TECHNOLOGY IN ELECTRONICS & COMMUNICATION ENGINEERING
SUBMITTED TO: SUBMITTED BY:
Er. Vijay Banga Name: Yogesh Sharma
HOD ECE Roll No. : 80602108132
ACKNOWLEDGMENT
I am highly grateful to the Er.Vijay Banga , HOD ( ECE), Amritsar College ofEngineering & Technology, (Amritsar), for providing this opportunity to carry out the sixmonth industrial training at Tata Teleservices Ltd.
I would like to expresses my gratitude to other faculty members of Electronics & Communication department of ACET, Amritsar for providing academic inputs, guidance &encouragement throughout the training period.
The author would like to express a deep sense of gratitude and thankful to the higher authorities of Company, without whose permission, wise counsel and ableguidance, it would have not been possible to pursue my training in this manner.The help rendered by Mr Gurminder Singh Bhullar, Supervisor (Technology) forExperimentation is greatly acknowledged.
Finally, I express my indebtedness to all who have directly or indirectly contributed to thesuccessful completion of my industrial training.
Yogesh Sharma
TABLE OF CONTENT
S.No. Content Page No.
1 Company Profile 12 Overview Of multiple acess technology 13 CDMA Advantage 24 BTS(Base Transceiver Station) 45 Huawei 3900 BTS 56 Practical Work 7
COMPANY PROFILE
Tata Teleservices Limited spearheads the Tata Group’s presence in thetelecom sector. The Tata Group had revenues of around US $62.5 bn inFinancial Year 2007-08, and includes over 90 companies, around 350,000employees worldwide and more than 3.2 million shareholders.
Incorporated in 1996, Tata Teleservices is the pioneer of the CDMA 1xtechnology platform in India. It has embarked on a growth path since theacquisition of Hughes Tele.com (India) Ltd [renamed Tata Teleservices(Maharashtra) Limited] by the Tata Group in 2002. It launched mobileoperations in January 2005 and today enjoys a pan-India presence throughexisting operations in all of India’s 22 telecom Circles. The company is alsothe market leader in the fixed wireless telephony market. The company’snetwork has been rated as the ‘Least Congested’ in India for last fourconsecutive quarters by the Telecom Regulatory Authority of Indiathrough independent surveys.
Today, Tata Teleservices Ltd, along with Tata Teleservices (Maharashtra)Ltd, serves over 36 million customers in more than 320,000 towns andvillages across the country, with a bouquet of telephony servicesencompassing Mobile Services, Wireless Desktop Phones, Public BoothTelephony and Wireline Services. Other services include value-addedservices like Voice Portal, Roaming, Post-paid Internet Services, Three-wayConferencing, Group Calling, Wi-Fi Internet, USB Modem, Data Cards,Calling Card Services and Enterprise Services. Some of the other productslaunched by the company include Pre-paid Wireless Desktop Phones,Public Phone Booths, Mobile Handsets and Voice & Data Services such asBREW Games, Voice Portal, Picture Messaging, Polyphonic Ring Tones,and Interactive Applications like news, cricket, astrology, etc.In December 2008, Tata Teleservices announced a unique reverse equityswap strategic agreement between its fully-owned telecom towersubsidiary, Wireless TT Info-Services Limited, and Quippo TelecomInfrastructure Limited—with the combined entity kicking off operationswith 18,000 towers, thereby becoming the largest independent entity in thisspace. Tata Teleservices’ bouquet of telephony services includes mobileservices, wireless desktop phones, public booth telephony and wirelineservices.
Board of Directors
Mr. Ratan N. TataDesignation : ChairmanCompany : Tata Teleservices Ltd.
Mr. K. A. ChaukarDesignation : Managing DirectorCompany : Tata Industries Ltd.
Mr. Anil Kumar SardanaDesignation : Managing DirectorCompany : Tata Teleservices Limited
.
Mr. N. S. RamachandranDesignation : Director,Company : Tata Teleservices Ltd.
Mr. N. SrinathDesignation : CEO & MDCompany : Tata Docomo.
Dr. Mukund Govind RajanDesignation : MD
Company : Tata Teleservices Maharashtra Ltd.
Mr. Anuj MaheshwariDesignation : DirectorCompany : Temasek Holdings AdvisorsIndia Pvt Ltd., ("THAIPL")
Mr Toshinari KuniedaDesignation : Senior Vice PresidentManaging Director Global Business DivisionCompany : NTT Docomo, INC.
Mr. Kiyoshi TokuhiroDesignation : Senior Vice President
Managing Director of Network DepartmentCompany : NTT Docomo, INC.
CODE DIVISION MULTIPLE ACCESS
Code division multiple access (CDMA) is a channel access method used by various radio communication
technologies. It should not be confused with the mobile phone
standards called cdmaOne, CDMA2000 (the 3G evolution of cdmaOne) and WCDMA (the 3G standard
used by GSM carriers), which are often referred to as simply CDMA, and use CDMA as an underlying
channel access method.
One of the basic concepts in data communication is the idea of allowing several transmitters to send
information simultaneously over a single communication channel. This allows several users to share a band
of frequencies . This concept is called multiple access. CDMA employs spread-spectrum technology and a
special coding scheme (where each transmitter is assigned a code) to allow multiple users to be multiplexed
over the same physical channel. By contrast, time division multiple access (TDMA) divides access by time,
while frequency-division multiple access (FDMA) divides it by frequency. CDMA is a form of spread-
spectrum signalling, since the modulated coded signal has a much higher data bandwidth than the data
being communicated.
An analogy to the problem of multiple access is a room (channel) in which people wish to talk to each other
simultaneously. To avoid confusion, people could take turns speaking (time division), speak at different
pitches (frequency division), or speak in different languages (code division). CDMA is analogous to the
last example where people speaking the same language can understand each other, but other languages are
perceived as noise and rejected. Similarly, in radio CDMA, each group of users is given a shared code.
Many codes occupy the same channel, but only users associated with a particular code can communicate.
The technology of code division multiple access channels have long been known. In the USSR, the first
work devoted to this subject was published in 1935 by Professor D.V. Aggeev in the "CDMA". It was
shown that through the use of linear methods, there are three types of signal separation: frequency, time
and compensatory. The technology of CDMA was used in 1957, when the young military radio engineer
Leonid Kupriyanovich in Moscow, made an experimental model of a wearable automatic mobile phone,
called LK-1 by him, with a base station. LK-1 has a weight of 3 kg, 20-30 km operating distance, and 20-
30 hours of battery life. The base station, as described by the author, could serve several customers. In
1958, Kupriyanovich made the new experimental "pocket" model of mobile phone. This phone weighed 0.5
kg. To serve more customers, Kupriyanovich proposed the device, named by him as correllator. In 1958,
the USSR also started the development of the "Altay" national civil mobile phone service for cars, based on
the Soviet MRT-1327 standard. The main developers of the Altay system were VNIIS (Voronezh Science
Research Institute of Communications) and GSPI (State Specialized Project Institute). In 1963 this service
started in Moscow and in 1970 Altay service was used in 30 USSR cities.
STEPS IN CDMA MODULATION
CDMA is a spread spectrum multiple access technique. A spread spectrum technique spreads the
bandwidth of the data uniformly for the same transmitted power. A spreading code is a pseudo-random
code that has a narrow Ambiguity function, unlike other narrow pulse codes. In CDMA a locally generated
code runs at a much higher rate than the data to be transmitted. Data for transmission is combined via
bitwise XOR (exclusive OR) with the faster code. The figure shows how a spread spectrum signal is
generated. The data signal with pulse duration of Tb is XOR’ed with the code signal with pulse duration
of Tc. Therefore, the bandwidth of the data signal is 1 / Tb and the bandwidth of the spread spectrum signal
is1 / Tc. Since Tc is much smaller than Tb, the bandwidth of the spread spectrum signal is much larger than
the bandwidth of the original signal. The ratioTb / Tc is called the spreading factor or processing gain and
determines to a certain extent the upper limit of the total number of users supported simultaneously by a
base station.
Each user in a CDMA system uses a different code to modulate their signal. Choosing the codes used to
modulate the signal is very important in the performance of CDMA systems. The best performance will
occur when there is good separation between the signal of a desired user and the signals of other users. The
separation of the signals is made by correlating the received signal with the locally generated code of the
desired user. If the signal matches the desired user's code then the correlation function will be high and the
system can extract that signal. If the desired user's code has nothing in common with the signal the
correlation should be as close to zero as possible (thus eliminating the signal); this is referred to as cross
correlation. If the code is correlated with the signal at any time offset other than zero, the correlation should
be as close to zero as possible. This is referred to as auto-correlation and is used to reject multi-path
interference.
In general, CDMA belongs to two basic categories: synchronous (orthogonal codes) and asynchronous
(pseudorandom codes).
Advantages of asynchronous CDMA over other techniques
Efficient Practical utilization of Fixed Frequency Spectrum
In theory, CDMA, TDMA and FDMA have exactly the same spectral efficiency but practically, each has
its own challenges – power control in the case of CDMA, timing in the case of TDMA, and frequency
generation/filtering in the case of FDMA.
TDMA systems must carefully synchronize the transmission times of all the users to ensure that they are
received in the correct timeslot and do not cause interference. Since this cannot be perfectly controlled in a
mobile environment, each timeslot must have a guard-time, which reduces the probability that users will
interfere, but decreases the spectral efficiency. Similarly, FDMA systems must use a guard-band between
adjacent channels, due to the unpredictable Doppler shift of the signal spectrum because of user mobility.
The guard-bands will reduce the probability that adjacent channels will interfere, but decrease the
utilization of the spectrum.
Flexible Allocation of Resources
Asynchronous CDMA offers a key advantage in the flexible allocation of resources i.e. allocation of
a PN codes to active users. In the case of CDM (synchronous CDMA), TDMA, and FDMA the
number of simultaneous orthogonal codes, time slots and frequency slots respectively is fixed hence
the capacity in terms of number of simultaneous users is limited. There are a fixed number of
orthogonal codes, timeslots or frequency bands that can be allocated for CDM, TDMA, and FDMA
systems, which remain underutilized due to the bursty nature of telephony and packetized data
transmissions. There is no strict limit to the number of users that can be supported in an
asynchronous CDMA system, only a practical limit governed by the desired bit error probability,
since the SIR (Signal to Interference Ratio) varies inversely with the number of users. In a bursty
traffic environment like mobile telephony, the advantage afforded by asynchronous CDMA is that
the performance (bit error rate) is allowed to fluctuate randomly, with an average value determined
by the number of users times the percentage of utilization. Suppose there are 2N users that only talk
half of the time, then 2N users can be accommodated with the same average bit error probability as
N users that talk all of the time. The key difference here is that the bit error probability for N users
talking all of the time is constant, whereas it is a random quantity (with the same mean) for 2N
users talking half of the time.
In other words, asynchronous CDMA is ideally suited to a mobile network where large numbers of
transmitters each generate a relatively small amount of traffic at irregular intervals. CDM (synchronous
CDMA), TDMA, and FDMA systems cannot recover the underutilized resources inherent to bursty traffic
due to the fixed number of orthogonal codes, time slots or frequency channels that can be assigned to
individual transmitters. For instance, if there are N time slots in a TDMA system and 2N users that talk half
of the time, then half of the time there will be more than N users needing to use more than N timeslots.
Furthermore, it would require significant overhead to continually allocate and deallocate the orthogonal
code, time-slot or frequency channel resources. By comparison, asynchronous CDMA transmitters simply
send when they have something to say, and go off the air when they don't, keeping the same PN signature
sequence as long as they are connected to the system.
Spread-spectrum characteristics of CDMA
Most modulation schemes try to minimize the bandwidth of this signal since bandwidth is a limited
resource. However, spread spectrum techniques use a transmission bandwidth that is several orders of
magnitude greater than the minimum required signal bandwidth. One of the initial reasons for doing this
was military applications including guidance and communication systems. These systems were designed
using spread spectrum because of its security and resistance to jamming. Asynchronous CDMA has some
level of privacy built in because the signal is spread using a pseudo-random code; this code makes the
spread spectrum signals appear random or have noise-like properties. A receiver cannot demodulate this
transmission without knowledge of the pseudo-random sequence used to encode the data. CDMA is also
resistant to jamming. A jamming signal only has a finite amount of power available to jam the signal. The
jammer can either spread its energy over the entire bandwidth of the signal or jam only part of the entire
signal.
CDMA can also effectively reject narrow band interference. Since narrow band interference affects only a
small portion of the spread spectrum signal, it can easily be removed through notch filtering without much
loss of information. Convolution encoding and interleaving can be used to assist in recovering this lost
data. CDMA signals are also resistant to multipath fading. Since the spread spectrum signal occupies a
large bandwidth only a small portion of this will undergo fading due to multipath at any given time. Like
the narrow band interference this will result in only a small loss of data and can be overcome.
Another reason CDMA is resistant to multipath interference is because the delayed versions of the
transmitted pseudo-random codes will have poor correlation with the original pseudo-random code, and
will thus appear as another user, which is ignored at the receiver. In other words, as long as the multipath
channel induces at least one chip of delay, the multipath signals will arrive at the receiver such that they are
shifted in time by at least one chip from the intended signal. The correlation properties of the pseudo-
random codes are such that this slight delay causes the multipath to appear uncorrelated with the intended
signal, and it is thus ignored.
Some CDMA devices use a rake receiver which exploits multipath delay components to improve the
performance of the system. A rake receiver combines the information from several correlators, each one
tuned to a different path delay, producing a stronger version of the signal than a simple receiver with a
single correlation tuned to the path delay of the strongest signal.
Frequency reuse is the ability to reuse the same radio channel frequency at other cell sites within a cellular
system. In the FDMA and TDMA systems frequency planning is an important consideration. The
frequencies used in different cells must be planned carefully to ensure signals from different cells do not
interfere with each other. In a CDMA system, the same frequency can be used in every cell, because
channelization is done using the pseudo-random codes. Reusing the same frequency in every cell
eliminates the need for frequency planning in a CDMA system; however, planning of the different pseudo-
random sequences must be done to ensure that the received signal from one cell does not correlate with the
signal from a nearby cell.
Since adjacent cells use the same frequencies, CDMA systems have the ability to perform soft hand offs.
Soft hand offs allow the mobile telephone to communicate simultaneously with two or more cells. The best
signal quality is selected until the hand off is complete. This is different from hard hand offs utilized in
other cellular systems. In a hard hand off situation, as the mobile telephone approaches a hand off, signal
strength may vary abruptly. In contrast, CDMA systems use the soft hand off, which is undetectable and
provides a more reliable and higher quality signal.
Collaborative CDMA
In a recent study, a novel collaborative multi-user transmission and detection scheme called Collaborative
CDMA has been investigated for the uplink that exploits the differences between users’ fading channel
signatures to increase the user capacity well beyond the spreading length in multiple access interference
(MAI) limited environment. The authors show that it is possible to achieve this increase at a low
complexity and high bit error rate performance in flat fading channels, which is a major research challenge
for overloaded CDMA systems. In this approach, instead of using one sequence per user as in conventional
CDMA, the authors group a small number of users to share the same spreading sequence and enable group
spreading and dispreading operations. The new collaborative multi-user receiver consists of two stages:
group multi-user detection (MUD) stage to suppress the MAI between the groups and a low complexity
maximum-likelihood detection stage to recover jointly the co-spread users’ data using minimum Euclidean
distance measure and users’ channel gain coefficients. In CDM signal security is high.
USES
A CDMA2000 Mobile Phone
One of the early applications for code division multiplexing is in GPS. This predates and is distinct
from its use in mobile phones.
The Qualcomm standard IS-95, marketed as cdmaOne.
The Qualcomm standard IS-2000, known as CDMA2000. This standard is used by several mobile
phone companies, including the Globalstar satellite phone network.
The UMTS 3G mobile phone standard, which uses W-CDMA.
CDMA has been used in the OmniTRACS satellite system for transportation logistics.
Network Components
A digital wireless system has 4 basic components:
Mobile phones (personal station (PS), mobile station (MS), portable,subscriber, user terminal (UT), handheld, or mobile)
● Base Station Transceiver Subsystem (BTS), Base Station (BS), or cell site.
● Base Station Controller (BSC), Mobile Switching Center (MSC), MobileTelephone Switching Office (MTSO), or switch.
● Public switched telephone network (PSTN).
Infrastructure Equipment
BSC Indoor BTS
Outdoor BTS
Infrastructure Equipment
Base Station Controller (BSC)
BSC functions:
● Call control processes.● Database of subscribers.● Record calls for billing.● Switch the calls to the PSTN.● Vocoding of the voice signal.
Base Station Transceiver System
BTS functions are:
● CDMA processing of all signals.● Transmitting and receiving of all RF signals.There are 2 types of BTS’ one for indoor installation and the other for outdoorinstallation.
BTS Sectorization
A BTS may have up to 9 sectors. Each sector operates like an independent BTSbut only additional hardware is required. In CDMA the addition of sectors in aBTS further increases the capacity.
COMPONENTS USED AND THEIR FEATURES
During my 6 months training in Tata Teleservices Ltd. , I was provided a deep insight as to how does Tata Teleservices Ltd.., cries and provides CDMA technology to its subscribers in Punjab. With due time I learnt that at the centre of all this was a very tricky and tiresome job of “Operation and Maintenance of BTS and RAN”.
As explained earlier in the Report BTS (Base transceiver Station) remains the very heart of the entire operation. Nowadays TTSL makes use of two types of BTS’s for the above mentioned purpose .These are the following:--
Motorola 1X SC4812-MC
Huawei 3900
MOTOROLA 1X SC4812-MC
SC4812T-MC Multicarrier BTS Overview
INCREASED FLEXIBILITY
Motorola’s new SC4812T-MC base station offers operators moreflexibility than ever before. The SC4812T-MC base stationincorporates all of the features and functionality of the SC4812Tproduct, with the added benefit of Multicarrier LPA operation. Thisfunctionality enables dynamic power allocation across both sectorsand carriers for maximum power efficiency and flexibility.Based on the industry leading and field-proven Super Cell (SC)architecture, the SC4812T-MC base station is designed for optimumefficiency in medium to high capacity cell sites. The SC4812T-MCbase station addresses the need for scalable power, improvementsin operating efficiency and an increase in deployment flexibility.
DYNAMIC RF POWER
• Multicarrier Trunking – Scalable, efficient use of powerThe SC4812T-MC is the first Motorola CDMA BTS to utilize aninnovative linear trunking method that provides more efficient use ofRF power than ever before. The SC4812T-MC power output ofevery LPA is dynamically shared across both sectors and carriersfor maximum efficiency. The RF power is allocated based on trafficloading. This allows the cell site to handle traffic that wouldotherwise go unserved. The result is an increase in operationalflexibility and higher effective power.
• Intelligent Performance – Power output flexibilityIn addition to the efficient use of RF power, the SC4812T-MCintroduces the ability for operators to add carriers to the BTS withouthaving to add LPAs. Likewise, LPAs can be added without havingto add carriers. This enables operators to size their power to fit therequirements of each site. This enhancement reduces costs,operating expenses, and increases flexibility.SCTM4812T-MC800 MHz Multicarrier BTS:- MORE FLEXIBILITY- DYNAMIC RF POWERIS95 A / B / CDMA2000
SC4812T-MC @ 800 MHzBTS Equipment Overview
BTS Configurations
The upgrade procedures in this publication apply to the two principal configurations, based on input power, of the SC4812T and SC4812T–MC BTS frames:
S +27 Vdc
S –48 Vdc
Original Design SC4812T +27Vdc Starter Frames
Before July 1999, a few +27 Vdc starter frames were produced with the I/O panels used for SC4812 non–trunked BTS frames. These panels have the EXP expansion connector housing for received signal distribution located at the top rear of the frame (Figure 1-3). These frames require a different 10/100base–T Fast Ethernet interface housing kit than later production frames. Before ordering packet backhaul upgrade parts and materials, users with older frames should perform an inspection of their equipment to determine if they have this type of frame.
Later Production SC4812TFrames
Since July 1999 both the +27 Vdc and –48 Vdc frames have been enhanced and the I/O panels have changed. The following sections provide information on frame type identification, and also a chart identifying the kit used with each type of frame. Refer to the chart to
determine the type of equipment needed for the frame at the site.
Overview
Proper frame identification is important in order to determine which steps are necessary in this upgrade procedure. This section provides information regarding the slight differences in the SC4812T products (original and upgrade designs). Once the frame type has been identified, use Table 1-10, titled “+27 Vdc Frame Kit Identification Chart” to determine which Packet Backhaul kit is required to perform the upgrade.
SC4812T +27 Vdc OriginalDesign
The following table identifies the visual and mechanical differences of the Original Design frames.
Early Starter Frame Later Starter Frame Expansion Frame
S EXP Housing located on the rear right side.
S TX OUT located to the right of the EXP Housing.
S EXP Housing located on the front right side
S RX IN located 1A–6A located towards the rear right side.
S EXP IN located in the middle right.
S EXP OUT located in the front right.
Motorola_SC4812T-MC
Huawei 3900 BTS
1.1 Appearance of the BTS CabinetThe BTS3900 cabinet is designed in compliance with the IEC297 standards and it is a vertical cabinet.
Appearance
Dimensions
Figure 1-1 shows the appearance of the BTS3900.
Figure 1-1 Appearance of the BTS3900 cabinet
The dimensions of the BTS3900 cabinet are as follows:
l Height x width x depth = 900 mm [35.43 in.] x 600 mm [23.62 in.] x 450 mm [17.72 in.]
1.2 Structure of the BTS CabinetThe BTS3900 cabinet adopts the module structure. It consists of the BBU3900, CRFU, FAN, DCDU-01, and SLPU (optional).
A space is reserved at the bottom of the cabinet for the installation of user devices such as the transmission equipment.
Figure 1-2 shows the internal structure of the BTS3900 cabinet.
Issue 03 (2008-12-25) Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
1-3
Airbridge BTS3900 CDMA Base StationHardware Description 1 BTS Cabinet
Figure 1-2 Internal structure of the BTS3900 cabinet
(1) CRFU (2) FAN unit (3) SLPU (optional)
(4) BBU3900 (5) DCDU
NOTE
The type of the DCDU configured for the BTS3900 is DCDU-01.
The main components of the BTS3900 cabinet described are as follows:
Module Full Name
CRFU CDMA Radio Frequency Unit
FAN FAN
SLPU Signal Lightning Protection unit
BBU3900 BaseBand Unit
DCDU-01 Direct Current Distribution Unit
1.3 Configuration of the BTS CabinetThe BTS3900 cabinet supports the typical configuration with three CRFUs and the full configuration with six CRFUs. The SLPU is an optional component of the BTS3900 cabinet.
Figure 1-3 and Figure 1-4 show the typical configuration and full configuration of the BTS3900 cabinet respectively.
1-4 Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
Issue 03 (2008-12-25)
1 BTS CabinetAirbridge BTS3900 CDMA Base Station
Hardware Description
Figure 1-3 Typical configuration of the BTS3900 cabinet
Issue 03 (2008-12-25) Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
1-5
Airbridge BTS3900 CDMA Base StationHardware Description 1 BTS Cabinet
Figure 1-4 Full configuration of the BTS3900 cabinet
Table 1-1 describes the functions of the main components of the BTS3900 cabinet.
Table 1-1 Functions of the main components of the BTS3900 cabinet
Component Description
CRFU The CRFU is the CDMA RF unit of the BTS3900. It receives and sends radio signals for the communication between the radio network system and the MSs.
FAN The FAN is the fan unit of the BTS3900. It houses fans for heat dissipation in the BTS3900 cabinet.
BBU3900 The BBU3900 is the baseband unit of the BTS3900. It performs resource management, operation maintenance, and environment monitoring for the BTS.
DCDU-01 The DCDU-01 is the direct current distribution unit of the BTS3900. It supports one DC input and multiple DC outputs.
1-6 Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
Issue 03 (2008-12-25)
1 BTS CabinetAirbridge BTS3900 CDMA Base Station
Hardware Description
Component Description
SLPU (optional) It is the protection unit of the BTS3900 cabinet, and it houses the UELP and UFLP board for protecting the E1/T1 and FE signals from lightning surge.
1.4 Technical Specifications of the BTS CabinetThis describes the technical specifications of the BTS3900 cabinet.
Table 1-2 lists the technical specifications of the BTS3900 cabinet.
Table 1-2 Technical specifications of the BTS3900 cabinet
Item Specification
Dimension s
Height x width x depth = 900 mm [35.43 in.] x 600 mm [23.62 in.] x 450 mm[17.72 in.]
Weight Full configuration: ≤ 160 kg [352.8 lb]
Operation voltage
–48 V DC: –38.4 V DC to –57 V DC
Power consumpti on
Configuration Maximum power consumption for typical configuration
S(1/1/1) 640 W
S(4/4/4) 1320 W
NOTE
l The power consumption above is the maximum power consumption measured when the system working at 800 MHz in typical configuration uses 220 V AC power supply.
l The maximum power consumption does not include the power consumption of the transmission equipment and of the battery charge.
l The maximum power consumption varies with different operating frequency bands and different configurations of the BTSs.
Issue 03 (2008-12-25) Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
2-1
Airbridge BTS3900 CDMA Base StationHardware Description 2 BTS Components
2 BTS
Components
About This Chapter
The components of the BTS3900 cabinet include the BBU3900, CRFU, DCDU-01, SLPU (optional) and FAN.
2.1 BBU3900The BBU3900 is the baseband unit of the BTS3900. The BBU3900 performs resource management, operation and maintenance, and environment monitoring for the BTS system.
2.2 CRFUThe CRFU is the CDMA RF unit of the BTS3900 cabinet. It receives and sends radio signals for the communication between the radio network system and the MSs.
2.3 DCDU-01The DCDU-01 is the DC distribution unit for providing power input for the components in the cabinet.
2.4 SLPU (Optional)The SLPU is the universal signal lightning protection unit configured out of the BBU3900 cabinet. It protects the E1/T1 and FE signals from lightning strike.
2.5 FANThe FAN is the fan box unit for dissipating heat in the cabinet. A FAN unit houses four independent fans.
2-2 Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
Issue 03 (2008-12-25)
2 BTS ComponentsAirbridge BTS3900 CDMA Base Station
Hardware Description
2.1 BBU3900The BBU3900 is the baseband unit of the BTS3900. The BBU3900 performs resource management, operation and maintenance, and environment monitoring for the BTS system.
2.1.1 Hardware Configuration of the BBU3900The BBU3900 can be configured with the CMPT, HECM or HCPM, FAN, UPEU, USCU, UTRP, and UELP or UFLP.
2.1.2 CMPTThe CMPT is the main processing and transmission unit. The CMPT processes and transmits the data between the BTS and the BSC, controls and manages the BTS, and provides clock signals for the BTS.
2.1.3 HCPMThe HCPM is a CDMA2000 1X channel processing board. It processes the CDMA2000 1X service data on forward and reverse channels. By default, the HCPM is configured with one CSM6700 chip.
2.1.4 HECMThe HECM is a CDMA2000 1xEV-DO channel processing board. It processes the CDMA20001xEV-DO service data on forward and reverse channels. By default, the HECM is configured with one CSM6800 chip.
2.1.5 UPEUThe UPEU supplies power to the BBU3900. Therefore, it is mandatory. The UPEU converts+24 V DC or –48 V DC power into +12 V DC power.
2.1.6 FANThe fan implements the heat dissipation function of the BBU3900.
2.1.7 UTRPThe UTRP is a universal extension transmission processing unit. The UTRP supports E1/T1 transmission ports.
2.1.8 UELPA UELP provides lightning protection for four E1/T1 links.
2.1.9 UFLPA UFLP provides lightning protection for FE signals. It supports two Ethernet connections.
2.1.10 USCUThe USCU is compatible with six types of satellite cards. It provides absolute time information and 1PPS reference clock source for the CMPT. In addition, the USCU supports RGPS and BITS ports.
2.1.1 Hardware Configuration of the BBU3900The BBU3900 can be configured with the CMPT, HECM or HCPM, FAN, UPEU, USCU, UTRP, and UELP or UFLP.
Appearance of the BBU3900
Figure 2-1 shows the BBU3900.
Issue 03 (2008-12-25) Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
2-3
Airbridge BTS3900 CDMA Base StationHardware Description 2 BTS Components
Figure 2-1 BBU3900
Board Configuration of the BBU3900
Figure 2-2 shows the board configuration of the BBU3900. Table 2-1 lists the boards in theBBU3900.
Figure 2-2 Board configuration of the BBU3900
Table 2-1 Boards in the BBU3900
Board Full Name Function
CMPT CDMA Main Processing&Transmission Unit
l It processes and transmits data between the BTS and the BSC, controls and manages the entire BTS, and provides clock signals for the BTS system.
l It supports E1, T1, and FE links and supports IP transmission.
HCPM HERT channel processing module
It processes the CDMA2000 1X service data on forward and reverse channels.
HECM HERT Enhance ChannelProcessing Module
It processes the CDMA2000 1x- EV-DO service data on forward and reverse channels.
2-4 Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
Issue 03 (2008-12-25)
2 BTS ComponentsAirbridge BTS3900 CDMA Base Station
Hardware Description
Board Full Name Function
UTRP Universal Extension Transmission Processing Unit
It provides connection between the BBU3900 and the BSC, and supports E1/T1 and IP transmission.
UELP Universal E1/T1 LightingProtection Unit
It provides lightning protection for E1/T1 signals.
UFLP Universal FE/GE LightingProtection Unit
It provides lightning protection for FE signals.
FAN FAN Unit It provides heat dissipation for the BBU3900.
UPEU Universal Power andEnvironment Interface Unit
It converts –48 V or +24 V DC power into +12 V DC power and provides environment monitoring signal ports.
USCU Universal Satellite Card andClock Unit
It provides the input port for external signals (including satellite clock signals) and provides synchronization clock signals for the BBU3900 and the RF modules connected to the BBU3900.
Configuration Principles of the BBU3900l CMPT configuration
– A maximum of two CMPTs working in 1+1 backup mode can be configured.
– Each CMPT provides four E1/T1 ports and two FE ports. You can configure the CMPTs based on capacity requirements and service types.
l HCPM configuration
– A maximum of six HCPMs can be configured.
– An HCPM reserves three SFP ports and supports removable optical modules.
– An HCPM is configured with only one CSM6700 chip. The chip processes 285 forward channels and 256 reverse channels.
l HECM configuration
– A maximum of six HECMs can be configured.
– An HECM reserves three SFP ports and supports removable optical modules.
– An HECM is configured with only one CSM6800 chip, which supports 192 subscribers.
l UTRP configuration
– A maximum of two UTRPs working in load sharing mode or 1+1 backup mode can be configured.
– Each UTRP provides eight E1/T1 ports.
l FAN configuration
Issue 03 (2008-12-25) Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
2-5
Airbridge BTS3900 CDMA Base StationHardware Description 2 BTS Components
A maximum of one FAN can be configured.
l UPEU configuration
A maximum of two UPEUs working in 1+1 backup mode can be configured.
l USCU configuration
A maximum of two USCUs can be configured. The USCU supports GPS or GPS/ GLONASS satellite card and RGPS signals.
l UELP configuration
A maximum of two UELPs can be configured. A UELP provides lightning protection for four E1/T1 links.
l UFLP configuration
A maximum of two UFLPs can be configured. A UFLP provides lightning protection forFE signals and supports two Ethernet connections.
NOTE
2.1.2 CMPT
l With hybrid configuration of HCPMs and HECMs, the BBU3900 supports CDMA2000 1X and 1xEV- DO services.
l The BBU3900 supports hybrid configuration of UELPs and UFLPs.
l The UELP/UFLP or the UTRP cannot be simultaneously configured in the BBU3900.
l When the BBU3900 is configured with the UTRP, the SLPU can be used to provide lightning protection.
l The SLPU is an external universal lightning protection unit. It can house the UELP/UFLP. It is used for the lightning protection of the E1/T1/FE cables. The SLPU supports mixed configuration of the UELP and the UFLP. A maximum of four lightning protection boards can be configured.
l The BBU3900 can be configured with the CMPT and UTRP at the same time.
l If a new site requires more than four E1/T1 links, Huawei recommends that you use the E1/T1 resources on the UTRP directly.
l If an expanded site requires more than four E1/T1 links, Huawei recommends that you use the E1/ T1 resources provided by the extended transmission board, apart from the four E1/T1 links on the main control transmission board.
The CMPT is the main processing and transmission unit. The CMPT processes and transmits the data between the BTS and the BSC, controls and manages the BTS, and provides clock signals for the BTS.
2.1.2.1 CMPT PanelThis describes the exterior and the ports and indicators of the CMPT panel.
2.1.2.2 DIP Switches on the CMPTThis describes the positions and settings of the DIP switches on the CMPT.
2.1.2.3 Technical Specifications of the CMPTThis describes the technical specifications of the CMPT.
CMPT Panel
This describes the exterior and the ports and indicators of the CMPT panel.
2-6 Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
Issue 03 (2008-12-25)
(1) ETH port (2) FE0 port (3) FE1 port (4) USB port
(5) TEST port (6) E1/T1 port (7) GPS port
2 BTS ComponentsAirbridge BTS3900 CDMA Base Station
Hardware Description
Exterior
Ports
Figure 2-3 shows the CMPT panel.
Figure 2-3 CMPT panel
Table 2-2 lists the ports on the CMPT panel.
Table 2-2 CMPT ports
Port Description
ETH port Commissioning port
TEST port Clock test port
USB port Reserved port
E1/T1 port Used to transmit data between the BTS and the BSC
FE0 port Used to transmit data between the BTS and the BSC
Electric port, supporting electric cable
FE1 port Used to transmit data between the BTS and the BSC
SFP port, supporting SFP electric/optical cable
NOTEWhen the optical cable is used, you must install the removable optical module.
GPS port Used to connect the GPS antenna
Indicators
Table 2-3 lists the indicators on the CMPT panel.
Issue 03 (2008-12-25) Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
2-7
Airbridge BTS3900 CDMA Base StationHardware Description 2 BTS Components
Table 2-3 Indicators on the panel
Indicato r
Color Meaning Description NormalState
RUN Green Operation indicator
l ON: There is power input, but the board is faulty.
Blinking at0.5Hz
l OFF: There is no power input, or the board is faulty.
l Blinking at 4 Hz: The board is in the loading state.
l Blinking at 0.5 Hz: The board functions normally.
l Blinking at 0.25 Hz: The board is being tested.
l Other: The board is faulty.
ALM Red Alarm l ON: The board must be replaced. Offindicator
l Blinking at 4 Hz: A critical alarm is generated.
l Blinking at 0.5 Hz: A major alarm is generated.
l Blinking at 0.25 Hz: A minor alarm is generated.
l Off: No alarm is generated.
ACT Green Active/ l ON: The active board is used. -standbyindicator
l OFF: The standby board is used.
TX Green Port indicator
Optical port On
l ON: The optical transmission is normal and the connection is normal.
l OFF: The optical transmission is faulty or the connection is disrupted.
Electrical port
l ON: There is signal output and the connection is normal.
l OFF: There is no signal output or the connection is disrupted.
2-8 Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
Issue 03 (2008-12-25)
2 BTS ComponentsAirbridge BTS3900 CDMA Base Station
Hardware Description
Indicato
Color Meaning Description Normalr State
RX Green Port Optical port Onindicator l ON: The optical transmission is
normal and the connection is normal.
l OFF: The optical transmission is faulty or the connection is disrupted.
Electrical port
l ON: There is signal input and the connection is normal.
l OFF: There is no signal input or the connection is disrupted.
ACT (Ethernet port)
Yellow Ethernet port indicator
l Blinking: The data is exchanged.
l OFF: No data is exchanged.
Blinking orOFF
LINK (Ethernet port)
Green Ethernet port indicator
l ON: The FE physical link functions On properly.
l OFF: The FE physical link is faulty.
DIP Switches on the CMPT
This describes the positions and settings of the DIP switches on the CMPT.
Figure 2-4 shows the DIP switches on the CMPT.
Figure 2-4 DIP switches on the CMPT
Table 2-4 lists the settings of the DIP switches on the CMPT.
Issue 03 (2008-12-25) Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
2-9
Airbridge BTS3900 CDMA Base StationHardware Description 2 BTS Components
Table 2-4 Settings of the DIP switches on the CMPT
Num ber
Function Description
SW1 Impedance matching of the E1/T1 port
The settings of SW1 are as follows:
l When the 100-ohm T1 twisted pair cable is used, bits 1 and 2 of SW1 are set to ON, and bits 3 and 4 are set to OFF.
l For the twisted pair cable (120-ohm E1), bits 1 and 2 of SW1 are set to OFF, and bits 3 and 4 are set to ON.
l When the 75-ohm E1 coaxial cable is used, all bits of SW1 are set to ON.
l Other location: reserved.
SW2 Settings for grounding of unbalanced cables
The four bits of SW2 are used to control the grounding status of four unbalanced E1/T1 cables. The settings of SW2 are as follows:
l For the coaxial cable grounded externally, all bits of SW2 are set to ON.
l For the coaxial cable ungrounded externally, all bits of SW2 are set to OFF.
l For the twisted cable, all bits of SW2 are set to OFF.
NOTECoaxial cable is ungrounded by fault, all bits of SW2 are set to OFF.
Technical Specifications of the CMPT
This describes the technical specifications of the CMPT.
The technical specifications of the CMPT are as follows:
l Dimensions (length x width x depth): 280 mm [11.02 in.] x 144.45 mm [5.69 in.] x 20.32 mm [0.80 in.]
l Input voltage: +12V
l Power consumption: ≤ 25 W
2.1.3 HCPMThe HCPM is a CDMA2000 1X channel processing board. It processes the CDMA2000 1X service data on forward and reverse channels. By default, the HCPM is configured with one CSM6700 chip.
2.1.3.1 HCPM PanelThis describes the exterior, ports, and indicators of the HCPM panel.
2.1.3.2 Technical Specifications of the HCPMThis describes the technical specifications of the HCPM.
HCPM Panel
This describes the exterior, ports, and indicators of the HCPM panel.
2-10 Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
Issue 03 (2008-12-25)
2 BTS ComponentsAirbridge BTS3900 CDMA Base Station
Hardware Description
Exterior
Figure 2-5 shows the HCPM panel.
Figure 2-5 HCPM panel
(1) MDR26 port (2) SFP port
Ports
Table 2-5 lists the ports on the HCPM panel.
Table 2-5 Ports on the HCPM panel
Port Description
SFP port It is connected to the RF module.
l It can be connected to the optical module, and then to optical fibers.
l It can also be directly connected to an SFPcable.
MDR26 port The GIGA port is reserved.
Indicators
Table 2-6 lists the indicators on the HCPM panel.
Table 2-6 Indicators on the panel
Indic ator
Color Meaning
Description NormalState
RUN Green Running indicator
l Blinking at 4 Hz: The board is being initialized or the software is being loaded.
Blinking at0.5 Hz
l Blinking at 0.5 Hz: The board functionsproperly.
l Other: The board is faulty.
Issue 03 (2008-12-25) Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
2-11
Airbridge BTS3900 CDMA Base StationHardware Description 2 BTS Components
Indic ator
Color Meaning Description NormalState
ALM Red Alarm indicator
l
l
ON: The board must be replaced.
Blinking at 4 Hz: A critical alarm is
OFF
generated.
l Blinking at 0.5 Hz: A major alarm is generated.
l Blinking at 0.25 Hz: A minor alarm is generated.
l OFF: No alarm is generated.
ACT Green Operation l On: The board functions properly. ONindicator
l Blinking at 4 Hz: An alarm of ATM bus is generated.
l Blinking at 0.5 Hz: The main control signaling link is disconnected.
l Blinking at 0.25 Hz: The CSM chip is faulty.
TX Green Port indicator
Optical port ON
l ON: The optical transmission is normal and the connection is normal.
l OFF: The optical transmission is faulty or the connection is disrupted.
Electrical port
l ON: There is signal output and the connection is normal.
l OFF: There is no signal output or the connection is disrupted.
RX Green Port indicator
Optical port ON
l ON: The optical transmission is normal and the connection is normal.
l OFF: The optical transmission is faulty or the connection is disrupted.
Electrical port
l ON: There is signal input and the connection is normal.
l OFF: There is no signal input or the connection is disrupted.
Technical Specifications of the HCPM
This describes the technical specifications of the HCPM.
The technical specifications of the HCPM are as follows:
2-12 Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
Issue 03 (2008-12-25)
2 BTS ComponentsAirbridge BTS3900 CDMA Base Station
Hardware Description
l Dimensions (length x width x depth): 280 mm [11.02 in.] x 144.45 mm [5.69?in.] x 20.32 mm [0.80 in.]
l Input voltage: +12V
l Power consumption: ≤ 20 W
l Channel processing capacity: 285 forward channels and 256 reverse channels
2.1.4 HECMThe HECM is a CDMA2000 1xEV-DO channel processing board. It processes the CDMA20001xEV-DO service data on forward and reverse channels. By default, the HECM is configured with one CSM6800 chip.
2.1.4.1 HECM PanelThis describes the exterior, ports, and indicators of the HECM panel.
2.1.4.2 Technical Specifications of the HECMThis describes the technical specifications of the HECM.
HECM Panel
This describes the exterior, ports, and indicators of the HECM panel.
Exterior
Figure 2-6 shows the HECM panel.
Figure 2-6 HECM panel
(1) MDR26 port (2) SFP port
Ports
Table 2-7 lists the ports on the HECM panel.
Issue 03 (2008-12-25) Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
2-13
Airbridge BTS3900 CDMA Base StationHardware Description 2 BTS Components
Table 2-7 Ports on the HECM panel
Port Description
SFP port It is connected to the RF module.
l It can be connected to the optical module, and then to optical fibers.
l It can also be directly connected to an SFPcable.
MDR26 port The GIGA port is reserved.
Indicators
Table 2-8 lists the indicators on the HECM panel.
Table 2-8 Indicators on the panel
Indic ator
Color Meaning Description NormalState
RUN Green Running indicator
l Blinking at 4 Hz: The board is being initialized or the software is being loaded.
l Blinking at 0.5 Hz: The board functions properly.
l Other: The board is faulty.
Blinking at0.5 Hz
ALM Red Alarm indicator
l ON: The board must be replaced.
l Blinking at 4 Hz: A critical alarm is generated.
l Blinking at 0.5 Hz: A major alarm is generated.
l Blinking at 0.25 Hz: A minor alarm is generated.
l OFF: No alarm is generated.
OFF
ACT Green Operation indicator
l On: The board functions properly. ON
l Blinking at 4 Hz: An alarm of ATM bus is generated.
l Blinking at 0.5 Hz: The main control signaling link is disconnected.
l Blinking at 0.25 Hz: The CSM chip is faulty.
2-14 Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
Issue 03 (2008-12-25)
2 BTS ComponentsAirbridge BTS3900 CDMA Base Station
Hardware Description
Indic Color Meaning
Description Normalator State
TX Green Port Optical port ONindicator l ON: The optical transmission is normal
and the connection is normal.
l OFF: The optical transmission is faulty or the connection is disrupted.
Electrical port
l ON: There is signal output and the connection is normal.
l OFF: There is no signal output or the connection is disrupted.
RX Green Port indicator
2-14 Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
Issue 03 (2008-12-25)
Optical port ON
l ON: The optical transmission is normal and the connection is normal.
l OFF: The optical transmission is faulty or the connection is disrupted.
Electrical port
l ON: There is signal input and the connection is normal.
l OFF: There is no signal input or the connection is disrupted.
1.1 Appearance of the BTS CabinetThe BTS3900 cabinet is designed in compliance with the IEC297 standards and it is a vertical cabinet.
Appearance
Dimensions
Figure 1-1 shows the appearance of the BTS3900.
Figure 1-1 Appearance of the BTS3900 cabinet
The dimensions of the BTS3900 cabinet are as follows:
l Height x width x depth = 900 mm [35.43 in.] x 600 mm [23.62 in.] x 450 mm [17.72 in.]
1.2 Structure of the BTS CabinetThe BTS3900 cabinet adopts the module structure. It consists of the BBU3900, CRFU, FAN, DCDU-01, and SLPU (optional).
2-14 Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
Issue 03 (2008-12-25)
A space is reserved at the bottom of the cabinet for the installation of user devices such as the transmission equipment.
Figure 1-2 shows the internal structure of the BTS3900 cabinet.
Issue 03 (2008-12-25) Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
1-3
Airbridge BTS3900 CDMA Base StationHardware Description 1 BTS Cabinet
Figure 1-2 Internal structure of the BTS3900 cabinet
(1) CRFU (2) FAN unit (3) SLPU (optional)
(4) BBU3900 (5) DCDU
NOTE
The type of the DCDU configured for the BTS3900 is DCDU-01.
The main components of the BTS3900 cabinet described are as follows:
Module Full Name
CRFU CDMA Radio Frequency Unit
FAN FAN
SLPU Signal Lightning Protection unit
BBU3900 BaseBand Unit
DCDU-01 Direct Current Distribution Unit
1.3 Configuration of the BTS CabinetThe BTS3900 cabinet supports the typical configuration with three CRFUs and the full configuration with six CRFUs. The SLPU is an optional component of the BTS3900 cabinet.
Figure 1-3 and Figure 1-4 show the typical configuration and full configuration of the BTS3900 cabinet respectively.
1-4 Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
Issue 03 (2008-12-25)
1 BTS CabinetAirbridge BTS3900 CDMA Base Station
Hardware Description
Figure 1-3 Typical configuration of the BTS3900 cabinet
Issue 03 (2008-12-25) Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
1-5
Airbridge BTS3900 CDMA Base StationHardware Description 1 BTS Cabinet
Figure 1-4 Full configuration of the BTS3900 cabinet
Table 1-1 describes the functions of the main components of the BTS3900 cabinet.
Table 1-1 Functions of the main components of the BTS3900 cabinet
Component Description
CRFU The CRFU is the CDMA RF unit of the BTS3900. It receives and sends radio signals for the communication between the radio network system and the MSs.
FAN The FAN is the fan unit of the BTS3900. It houses fans for heat dissipation in the BTS3900 cabinet.
BBU3900 The BBU3900 is the baseband unit of the BTS3900. It performs resource management, operation maintenance, and environment monitoring for the BTS.
DCDU-01 The DCDU-01 is the direct current distribution unit of the BTS3900. It supports one DC input and multiple DC outputs.
1-6 Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
Issue 03 (2008-12-25)
1 BTS CabinetAirbridge BTS3900 CDMA Base Station
Hardware Description
Component Description
SLPU (optional) It is the protection unit of the BTS3900 cabinet, and it houses the UELP and UFLP board for protecting the E1/T1 and FE signals from lightning surge.
1.4 Technical Specifications of the BTS CabinetThis describes the technical specifications of the BTS3900 cabinet.
Table 1-2 lists the technical specifications of the BTS3900 cabinet.
Table 1-2 Technical specifications of the BTS3900 cabinet
Item Specification
Dimension s
Height x width x depth = 900 mm [35.43 in.] x 600 mm [23.62 in.] x 450 mm[17.72 in.]
Weight Full configuration: ≤ 160 kg [352.8 lb]
Operation voltage
–48 V DC: –38.4 V DC to –57 V DC
Power consumpti on
Configuration Maximum power consumption for typical configuration
S(1/1/1) 640 W
S(4/4/4) 1320 W
NOTE
l The power consumption above is the maximum power consumption measured when the system working at 800 MHz in typical configuration uses 220 V AC power supply.
l The maximum power consumption does not include the power consumption of the transmission equipment and of the battery charge.
l The maximum power consumption varies with different operating frequency bands and different configurations of the BTSs.
Issue 03 (2008-12-25) Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
2-1
Airbridge BTS3900 CDMA Base StationHardware Description 2 BTS Components
2 BTS
Components
About This Chapter
The components of the BTS3900 cabinet include the BBU3900, CRFU, DCDU-01, SLPU (optional) and FAN.
2.1 BBU3900The BBU3900 is the baseband unit of the BTS3900. The BBU3900 performs resource management, operation and maintenance, and environment monitoring for the BTS system.
2.2 CRFUThe CRFU is the CDMA RF unit of the BTS3900 cabinet. It receives and sends radio signals for the communication between the radio network system and the MSs.
2.3 DCDU-01The DCDU-01 is the DC distribution unit for providing power input for the components in the cabinet.
2.4 SLPU (Optional)The SLPU is the universal signal lightning protection unit configured out of the BBU3900 cabinet. It protects the E1/T1 and FE signals from lightning strike.
2.5 FANThe FAN is the fan box unit for dissipating heat in the cabinet. A FAN unit houses four independent fans.
2-2 Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
Issue 03 (2008-12-25)
2 BTS ComponentsAirbridge BTS3900 CDMA Base Station
Hardware Description
2.1 BBU3900The BBU3900 is the baseband unit of the BTS3900. The BBU3900 performs resource management, operation and maintenance, and environment monitoring for the BTS system.
2.1.1 Hardware Configuration of the BBU3900The BBU3900 can be configured with the CMPT, HECM or HCPM, FAN, UPEU, USCU, UTRP, and UELP or UFLP.
2.1.2 CMPTThe CMPT is the main processing and transmission unit. The CMPT processes and transmits the data between the BTS and the BSC, controls and manages the BTS, and provides clock signals for the BTS.
2.1.3 HCPMThe HCPM is a CDMA2000 1X channel processing board. It processes the CDMA2000 1X service data on forward and reverse channels. By default, the HCPM is configured with one CSM6700 chip.
2.1.4 HECMThe HECM is a CDMA2000 1xEV-DO channel processing board. It processes the CDMA20001xEV-DO service data on forward and reverse channels. By default, the HECM is configured with one CSM6800 chip.
2.1.5 UPEUThe UPEU supplies power to the BBU3900. Therefore, it is mandatory. The UPEU converts+24 V DC or –48 V DC power into +12 V DC power.
2.1.6 FANThe fan implements the heat dissipation function of the BBU3900.
2.1.7 UTRPThe UTRP is a universal extension transmission processing unit. The UTRP supports E1/T1 transmission ports.
2.1.8 UELPA UELP provides lightning protection for four E1/T1 links.
2.1.9 UFLPA UFLP provides lightning protection for FE signals. It supports two Ethernet connections.
2.1.10 USCUThe USCU is compatible with six types of satellite cards. It provides absolute time information and 1PPS reference clock source for the CMPT. In addition, the USCU supports RGPS and BITS ports.
2.1.1 Hardware Configuration of the BBU3900The BBU3900 can be configured with the CMPT, HECM or HCPM, FAN, UPEU, USCU, UTRP, and UELP or UFLP.
Appearance of the BBU3900
Figure 2-1 shows the BBU3900.
Issue 03 (2008-12-25) Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
2-3
Airbridge BTS3900 CDMA Base StationHardware Description 2 BTS Components
Figure 2-1 BBU3900
Board Configuration of the BBU3900
Figure 2-2 shows the board configuration of the BBU3900. Table 2-1 lists the boards in theBBU3900.
Figure 2-2 Board configuration of the BBU3900
Table 2-1 Boards in the BBU3900
Board Full Name Function
CMPT CDMA Main Processing&Transmission Unit
l It processes and transmits data between the BTS and the BSC, controls and manages the entire BTS, and provides clock signals for the BTS system.
l It supports E1, T1, and FE links and supports IP transmission.
HCPM HERT channel processing module
It processes the CDMA2000 1X service data on forward and reverse channels.
HECM HERT Enhance ChannelProcessing Module
It processes the CDMA2000 1x- EV-DO service data on forward and reverse channels.
2-4 Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
Issue 03 (2008-12-25)
2 BTS ComponentsAirbridge BTS3900 CDMA Base Station
Hardware Description
Board Full Name Function
UTRP Universal Extension Transmission Processing Unit
It provides connection between the BBU3900 and the BSC, and supports E1/T1 and IP transmission.
UELP Universal E1/T1 LightingProtection Unit
It provides lightning protection for E1/T1 signals.
UFLP Universal FE/GE LightingProtection Unit
It provides lightning protection for FE signals.
FAN FAN Unit It provides heat dissipation for the BBU3900.
UPEU Universal Power andEnvironment Interface Unit
It converts –48 V or +24 V DC power into +12 V DC power and provides environment monitoring signal ports.
USCU Universal Satellite Card andClock Unit
It provides the input port for external signals (including satellite clock signals) and provides synchronization clock signals for the BBU3900 and the RF modules connected to the BBU3900.
Configuration Principles of the BBU3900l CMPT configuration
– A maximum of two CMPTs working in 1+1 backup mode can be configured.
– Each CMPT provides four E1/T1 ports and two FE ports. You can configure the CMPTs based on capacity requirements and service types.
l HCPM configuration
– A maximum of six HCPMs can be configured.
– An HCPM reserves three SFP ports and supports removable optical modules.
– An HCPM is configured with only one CSM6700 chip. The chip processes 285 forward channels and 256 reverse channels.
l HECM configuration
– A maximum of six HECMs can be configured.
– An HECM reserves three SFP ports and supports removable optical modules.
– An HECM is configured with only one CSM6800 chip, which supports 192 subscribers.
l UTRP configuration
– A maximum of two UTRPs working in load sharing mode or 1+1 backup mode can be configured.
– Each UTRP provides eight E1/T1 ports.
l FAN configuration
Issue 03 (2008-12-25) Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
2-5
Airbridge BTS3900 CDMA Base StationHardware Description 2 BTS Components
A maximum of one FAN can be configured.
l UPEU configuration
A maximum of two UPEUs working in 1+1 backup mode can be configured.
l USCU configuration
A maximum of two USCUs can be configured. The USCU supports GPS or GPS/ GLONASS satellite card and RGPS signals.
l UELP configuration
A maximum of two UELPs can be configured. A UELP provides lightning protection for four E1/T1 links.
l UFLP configuration
A maximum of two UFLPs can be configured. A UFLP provides lightning protection forFE signals and supports two Ethernet connections.
NOTE
2.1.2 CMPT
l With hybrid configuration of HCPMs and HECMs, the BBU3900 supports CDMA2000 1X and 1xEV- DO services.
l The BBU3900 supports hybrid configuration of UELPs and UFLPs.
l The UELP/UFLP or the UTRP cannot be simultaneously configured in the BBU3900.
l When the BBU3900 is configured with the UTRP, the SLPU can be used to provide lightning protection.
l The SLPU is an external universal lightning protection unit. It can house the UELP/UFLP. It is used for the lightning protection of the E1/T1/FE cables. The SLPU supports mixed configuration of the UELP and the UFLP. A maximum of four lightning protection boards can be configured.
l The BBU3900 can be configured with the CMPT and UTRP at the same time.
l If a new site requires more than four E1/T1 links, Huawei recommends that you use the E1/T1 resources on the UTRP directly.
l If an expanded site requires more than four E1/T1 links, Huawei recommends that you use the E1/ T1 resources provided by the extended transmission board, apart from the four E1/T1 links on the main control transmission board.
The CMPT is the main processing and transmission unit. The CMPT processes and transmits the data between the BTS and the BSC, controls and manages the BTS, and provides clock signals for the BTS.
2.1.2.1 CMPT PanelThis describes the exterior and the ports and indicators of the CMPT panel.
2.1.2.2 DIP Switches on the CMPTThis describes the positions and settings of the DIP switches on the CMPT.
2.1.2.3 Technical Specifications of the CMPTThis describes the technical specifications of the CMPT.
CMPT Panel
This describes the exterior and the ports and indicators of the CMPT panel.
2-6 Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
Issue 03 (2008-12-25)
(1) ETH port (2) FE0 port (3) FE1 port (4) USB port
(5) TEST port (6) E1/T1 port (7) GPS port
2 BTS ComponentsAirbridge BTS3900 CDMA Base Station
Hardware Description
Exterior
Ports
Figure 2-3 shows the CMPT panel.
Figure 2-3 CMPT panel
Table 2-2 lists the ports on the CMPT panel.
Table 2-2 CMPT ports
Port Description
ETH port Commissioning port
TEST port Clock test port
USB port Reserved port
E1/T1 port Used to transmit data between the BTS and the BSC
FE0 port Used to transmit data between the BTS and the BSC
Electric port, supporting electric cable
FE1 port Used to transmit data between the BTS and the BSC
SFP port, supporting SFP electric/optical cable
NOTEWhen the optical cable is used, you must install the removable optical module.
GPS port Used to connect the GPS antenna
Indicators
Table 2-3 lists the indicators on the CMPT panel.
Issue 03 (2008-12-25) Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
2-7
Airbridge BTS3900 CDMA Base StationHardware Description 2 BTS Components
Table 2-3 Indicators on the panel
Indicato r
Color Meaning Description NormalState
RUN Green Operation indicator
l ON: There is power input, but the board is faulty.
Blinking at0.5Hz
l OFF: There is no power input, or the board is faulty.
l Blinking at 4 Hz: The board is in the loading state.
l Blinking at 0.5 Hz: The board functions normally.
l Blinking at 0.25 Hz: The board is being tested.
l Other: The board is faulty.
ALM Red Alarm l ON: The board must be replaced. Offindicator
l Blinking at 4 Hz: A critical alarm is generated.
l Blinking at 0.5 Hz: A major alarm is generated.
l Blinking at 0.25 Hz: A minor alarm is generated.
l Off: No alarm is generated.
ACT Green Active/ l ON: The active board is used. -standbyindicator
l OFF: The standby board is used.
TX Green Port indicator
Optical port On
l ON: The optical transmission is normal and the connection is normal.
l OFF: The optical transmission is faulty or the connection is disrupted.
Electrical port
l ON: There is signal output and the connection is normal.
l OFF: There is no signal output or the connection is disrupted.
2-8 Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
Issue 03 (2008-12-25)
2 BTS ComponentsAirbridge BTS3900 CDMA Base Station
Hardware Description
Indicato
Color Meaning Description Normalr State
RX Green Port Optical port Onindicator l ON: The optical transmission is
normal and the connection is normal.
l OFF: The optical transmission is faulty or the connection is disrupted.
Electrical port
l ON: There is signal input and the connection is normal.
l OFF: There is no signal input or the connection is disrupted.
ACT (Ethernet port)
Yellow Ethernet port indicator
l Blinking: The data is exchanged.
l OFF: No data is exchanged.
Blinking orOFF
LINK (Ethernet port)
Green Ethernet port indicator
l ON: The FE physical link functions On properly.
l OFF: The FE physical link is faulty.
DIP Switches on the CMPT
This describes the positions and settings of the DIP switches on the CMPT.
Figure 2-4 shows the DIP switches on the CMPT.
Figure 2-4 DIP switches on the CMPT
Table 2-4 lists the settings of the DIP switches on the CMPT.
Issue 03 (2008-12-25) Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
2-9
Airbridge BTS3900 CDMA Base StationHardware Description 2 BTS Components
Table 2-4 Settings of the DIP switches on the CMPT
Num ber
Function Description
SW1 Impedance matching of the E1/T1 port
The settings of SW1 are as follows:
l When the 100-ohm T1 twisted pair cable is used, bits 1 and 2 of SW1 are set to ON, and bits 3 and 4 are set to OFF.
l For the twisted pair cable (120-ohm E1), bits 1 and 2 of SW1 are set to OFF, and bits 3 and 4 are set to ON.
l When the 75-ohm E1 coaxial cable is used, all bits of SW1 are set to ON.
l Other location: reserved.
SW2 Settings for grounding of unbalanced cables
The four bits of SW2 are used to control the grounding status of four unbalanced E1/T1 cables. The settings of SW2 are as follows:
l For the coaxial cable grounded externally, all bits of SW2 are set to ON.
l For the coaxial cable ungrounded externally, all bits of SW2 are set to OFF.
l For the twisted cable, all bits of SW2 are set to OFF.
NOTECoaxial cable is ungrounded by fault, all bits of SW2 are set to OFF.
Technical Specifications of the CMPT
This describes the technical specifications of the CMPT.
The technical specifications of the CMPT are as follows:
l Dimensions (length x width x depth): 280 mm [11.02 in.] x 144.45 mm [5.69 in.] x 20.32 mm [0.80 in.]
l Input voltage: +12V
l Power consumption: ≤ 25 W
2.1.3 HCPMThe HCPM is a CDMA2000 1X channel processing board. It processes the CDMA2000 1X service data on forward and reverse channels. By default, the HCPM is configured with one CSM6700 chip.
2.1.3.1 HCPM PanelThis describes the exterior, ports, and indicators of the HCPM panel.
2.1.3.2 Technical Specifications of the HCPMThis describes the technical specifications of the HCPM.
HCPM Panel
This describes the exterior, ports, and indicators of the HCPM panel.
2-10 Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
Issue 03 (2008-12-25)
2 BTS ComponentsAirbridge BTS3900 CDMA Base Station
Hardware Description
Exterior
Figure 2-5 shows the HCPM panel.
Figure 2-5 HCPM panel
(1) MDR26 port (2) SFP port
Ports
Table 2-5 lists the ports on the HCPM panel.
Table 2-5 Ports on the HCPM panel
Port Description
SFP port It is connected to the RF module.
l It can be connected to the optical module, and then to optical fibers.
l It can also be directly connected to an SFPcable.
MDR26 port The GIGA port is reserved.
Indicators
Table 2-6 lists the indicators on the HCPM panel.
Table 2-6 Indicators on the panel
Indic ator
Color Meaning
Description NormalState
RUN Green Running indicator
l Blinking at 4 Hz: The board is being initialized or the software is being loaded.
Blinking at0.5 Hz
l Blinking at 0.5 Hz: The board functionsproperly.
l Other: The board is faulty.
Issue 03 (2008-12-25) Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
2-11
Airbridge BTS3900 CDMA Base StationHardware Description 2 BTS Components
Indic ator
Color Meaning Description NormalState
ALM Red Alarm indicator
l
l
ON: The board must be replaced.
Blinking at 4 Hz: A critical alarm is
OFF
generated.
l Blinking at 0.5 Hz: A major alarm is generated.
l Blinking at 0.25 Hz: A minor alarm is generated.
l OFF: No alarm is generated.
ACT Green Operation l On: The board functions properly. ONindicator
l Blinking at 4 Hz: An alarm of ATM bus is generated.
l Blinking at 0.5 Hz: The main control signaling link is disconnected.
l Blinking at 0.25 Hz: The CSM chip is faulty.
TX Green Port indicator
Optical port ON
l ON: The optical transmission is normal and the connection is normal.
l OFF: The optical transmission is faulty or the connection is disrupted.
Electrical port
l ON: There is signal output and the connection is normal.
l OFF: There is no signal output or the connection is disrupted.
RX Green Port indicator
Optical port ON
l ON: The optical transmission is normal and the connection is normal.
l OFF: The optical transmission is faulty or the connection is disrupted.
Electrical port
l ON: There is signal input and the connection is normal.
l OFF: There is no signal input or the connection is disrupted.
Technical Specifications of the HCPM
This describes the technical specifications of the HCPM.
The technical specifications of the HCPM are as follows:
2-12 Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.
Issue 03 (2008-12-25)
2 BTS ComponentsAirbridge BTS3900 CDMA Base Station
Hardware Description
l Dimensions (length x width x depth): 280 mm [11.02 in.] x 144.45 mm [5.69?in.] x 20.32 mm [0.80 in.]
l Input voltage: +12V
l Power consumption: ≤ 20 W
l Channel processing capacity: 285 forward channels and 256 reverse channels
2.1.4 HECMThe HECM is a CDMA2000 1xEV-DO channel processing board. It processes the CDMA20001xEV-DO service data on forward and reverse channels. By default, the HECM is configured with one CSM6800 chip.
2.1.4.1 HECM PanelThis describes the exterior, ports, and indicators of the HECM panel.
2.1.4.2 Technical Specifications of the HECMThis describes the technical specifications of the HECM.
HECM Panel
This describes the exterior, ports, and indicators of the HECM panel.
Exterior
Figure 2-6 shows the HECM panel.
Figure 2-6 HECM panel
(1) MDR26 port (2) SFP port
Ports
Table 2-7 lists the ports on the HECM panel.
Airbridge BTS3900 CDMA Base StationHardware Description 2 BTS Components
Table 2-7 Ports on the HECM panel
Port Description
SFP port It is connected to the RF module.
l It can be connected to the optical module, and then to optical fibers.
l It can also be directly connected to an SFPcable.
MDR26 port The GIGA port is reserved.
Indicators
Table 2-8 lists the indicators on the HECM panel.
Table 2-8 Indicators on the panel
Indic ator
Color Meaning Description NormalState
RUN Green Running indicator
l Blinking at 4 Hz: The board is being initialized or the software is being loaded.
l Blinking at 0.5 Hz: The board functions properly.
l Other: The board is faulty.
Blinking at0.5 Hz
ALM Red Alarm indicator
l ON: The board must be replaced.
l Blinking at 4 Hz: A critical alarm is generated.
l Blinking at 0.5 Hz: A major alarm is generated.
l Blinking at 0.25 Hz: A minor alarm is generated.
l OFF: No alarm is generated.
OFF
ACT Green Operation indicator
l On: The board functions properly. ON
l Blinking at 4 Hz: An alarm of ATM bus is generated.
l Blinking at 0.5 Hz: The main control signaling link is disconnected.
l Blinking at 0.25 Hz: The CSM chip is faulty.
Indic Color Meaning
Description Normalator State
TX Green Port Optical port ONindicator l ON: The optical transmission is normal
and the connection is normal.
l OFF: The optical transmission is faulty or the connection is disrupted.
Electrical port
l ON: There is signal output and the connection is normal.
l OFF: There is no signal output or the connection is disrupted.
RX Green Port indicator
Optical port ON
l ON: The optical transmission is normal and the connection is normal.
l OFF: The optical transmission is faulty or the connection is disrupted.
Electrical port
l ON: There is signal input and the connection is normal.
l OFF: There is no signal input or the connection is disrupted.
MICROWAVE TRANSMISSION
Microwave transmission refers to the technology of transmitting information or power by
the use of radio waves whose wavelengths are conveniently measured in small numbers of
centimeters; these are called microwaves. This part of the radio spectrum ranges
across frequencies of roughly 1.0 gigahertz(GHz) to 30 GHz. These correspond to
wavelengths from 30 centimeters down to 1.0 cm.
Microwaves are widely used for point-to-point communications because their
small wavelength allows conveniently-sized antennas to direct them in narrow beams, which
can be pointed directly at the receiving antenna. This allows nearby microwave equipment to
use the same frequencies without interfering with each other, as lower frequency radio waves
do. Another advantage is that the high frequency of microwaves gives the microwave band a
very large information-carrying capacity; the microwave band has a bandwidth 30 times that
of all the rest of the radio spectrum below it. A disadvantage is that microwaves are limited
to line of sight propagation; they cannot pass around hills or mountains as lower frequency
radio waves can.
Microwave radio transmission is commonly used in point-to-point communication
systems on the surface of the Earth, in satellite communications, and indeep space radio
communications. Other parts of the microwave radio band are used for radars, radio
navigation systems, sensor systems, and radio astronomy.
Microwave radio relay is a technology for transmitting digital and analog signals, such as
long-distance telephone calls and the relay of television programs to transmitters, between
two locations on a line of sight radio path. In microwave radio relay, radio waves are
transmitted between the two locations with directional antennas, forming a fixed radio
connection between the two points. Long daisy-chained series of such links form
transcontinental telephone and/or television communication systems.
How microwave radio relay links are formed
Because a line of sight radio link is made, the radio frequencies used occupy only a narrow
path between stations (with the exception of a certain radius of each station). Antennas used
must have a high directive effect; these antennas are installed in elevated locations such as
large radio towers in order to be able to transmit across long distances. Typical types of
antenna used in radio relay link installations are parabolic reflectors, shell
antennas and horn radiators, which have a diameter of up to 4 meters. Highly directive
antennas permit an economical use of the available frequency spectrum, despite long
transmission distances.
Planning considerations
Because of the high frequencies used, a quasi-optical line of sight between the stations is
generally required. Additionally, in order to form the line of sight connection between the
two stations, the first Fresnel zone must be free from obstacles so the radio waves
can propagate across a nearly uninterrupted path. Obstacles in the signal field cause unwanted
attenuation, and are as a result only acceptable in exceptional cases. High mountain peak or
ridge positions are often ideal: Europe's highest radio relay station, the Richtfunkstation
Jungfraujoch, is situated atop the Jungfraujoch ridge at an altitude of 3,705 meters
(12,156 ft) above sea level.
Obstacles, the curvature of the Earth, the geography of the area and reception issues arising
from the use of nearby land (such as in manufacturing and forestry) are important issues to
consider when planning radio links. In the planning process, it is essential that "path profiles"
are produced, which provide information about the terrain and Fresnel zones affecting the
transmission path. The presence of a water surface, such as a lake or river, in the mid-path
region also must be taken into consideration as it can result in a near-perfect reflection (even
modulated by wave or tide motions), creating multipath distortion as the two received signals
("wanted" and "unwanted") swing in and out of phase. Multipath fades are usually deep only
in a small spot and a narrow frequency band, so space and/or frequency diversity
schemes would be applied to mitigate these effects.
The effects of atmospheric stratification cause the radio path to bend downward in a typical
situation so a major distance is possible as the earth equivalent curvature increases from
6370 km to about 8500 km (a 4/3 equivalent radius effect). Rare events of temperature,
humidity and pressure profile versus height, may produce large deviations and distortion of
the propagation and affect transmission quality. High intensity rain and snow must also be
considered as an impairment factor, especially at frequencies above 10 GHz. All previous
factors, collectively known as path loss, make it necessary to compute suitable power
margins, in order to maintain the link operative for a high percentage of time, like the
standard 99.99% or 99.999% used in 'carrier class' services of most telecommunication
operators.
Over-horizon microwave radio relay
In over-horizon, or tropospheric scatter, microwave radio relay, unlike a standard microwave
radio relay link, the sending and receiving antennas do not use a line of sight transmission
path. Instead, the stray signal transmission, known as "tropo - scatter" or simply "scatter,"
from the sent signal is picked up by the receiving station. Signal clarity obtained by this
method depends on the weather and other factors, and as a result a high level of technical
difficulty is involved in the creation of a reliable over horizon radio relay link. Over horizon
radio relay links are therefore only used where standard radio relay links are unsuitable (for
example, in providing a microwave link to an island).
Usage of microwave radio relay systems
During the 1950s the AT&T Communications system of microwave radio grew to carry the
majority of US Long Distance telephone traffic, as well as intercontinental television
network signals. The prototype was called TDX and was tested with a connection between
New York City and Murray Hill, the location of Bell Laboratories in 1946. The TDX system
was set up between New York and Boston in 1947. The TDX was improved to the TD2,
which still used klystrons, and then later to the TD3 that used solid state electronics. The
main motivation in 1946 to use microwave radio instead of cable was that a large capacity
could be installed quickly and at less cost. It was expected at that time that the annual
operating costs for microwave radio would be greater than for cable. There were two main
reasons that a large capacity had to be introduced suddenly: Pent up demand for long distance
telephone service, because of the hiatus during the war years, and the new medium of
television, which needed more bandwidth than radio.
Similar systems were soon built in many countries, until the 1980s when the technology lost
its share of fixed operation to newer technologies such as fiber-optic cable and optical radio
relay links, both of which offer larger data capacities at lower cost per bit. Communication
satellites, which are also microwave radio relays, better retained their market share,
especially for television.
At the turn of the century, microwave radio relay systems are being used increasingly in
portable radio applications. The technology is particularly suited to this application because
of lower operating costs, a more efficient infrastructure, and provision of
direct hardware access to the portable radio operator.
OPTICAL FIBRE COMMUNICATION
Fiber-optic communication is a method of transmitting information from one place to
another by sending pulses of light through an optical fiber. The light forms
an electromagnetic carrier wave that is modulated to carry information. First developed in the
1970s, fiber-optic communication systems have revolutionized
the telecommunications industry and have played a major role in the advent of
the Information Age. Because of its advantages over electrical transmission, optical fibers
have largely replaced copper wire communications in core networks in the developed world.
The process of communicating using fiber-optics involves the following basic steps: Creating
the optical signal involving the use of a transmitter, relaying the signal along the fiber,
ensuring that the signal does not become too distorted or weak, receiving the optical signal,
and converting it into an electrical signal.
Technology
Modern fiber-optic communication systems generally include an optical transmitter to
convert an electrical signal into an optical signal to send into the optical fiber,
a cable containing bundles of multiple optical fibers that is routed through underground
conduits and buildings, multiple kinds of amplifiers, and an optical receiver to recover the
signal as an electrical signal. The information transmitted is typically digital
information generated by computers, telephone systems, and cable television companies.
Transmitters
The most commonly-used optical transmitters are
semiconductor devices such as light-emitting diodes (LEDs)
and laser diodes. The difference between LEDs and laser
diodes is that LEDs produce incoherent light, while laser
diodes produce coherent light. For use in optical
communications, semiconductor optical transmitters must be
designed to be compact, efficient, and reliable, while
operating in an optimal wavelength range, and directly modulated at high frequencies.
In its simplest form, an LED is a forward-biased p-n junction, emitting light
through spontaneous emission, a phenomenon referred to as electroluminescence. The
emitted light is incoherent with a relatively wide spectral width of 30-60 nm. LED light
transmission is also inefficient, with only about 1 % of input power, or about 100 microwatts,
eventually converted into launched power which has been coupled into the optical fiber.
However, due to their relatively simple design, LEDs are very useful for low-cost
applications.
Communications LEDs are most commonly made from gallium arsenide phosphide (GaAsP)
or gallium arsenide (GaAs). Because GaAsP LEDs operate at a longer wavelength than GaAs
LEDs (1.3 micrometers vs. 0.81-0.87 micrometers), their output spectrum is wider by a factor
of about 1.7. The large spectrum width of LEDs causes higher fiber dispersion, considerably
limiting their bit rate-distance product (a common measure of usefulness). LEDs are suitable
primarily for local-area-network applications with bit rates of 10-100 Mbit/s and transmission
distances of a few kilometers. LEDs have also been developed that use several quantum
wells to emit light at different wavelengths over a broad spectrum, and are currently in use
for local-area WDM networks.
Today, LEDs have been largely superseded by VCSEL (Vertical Cavity Surface Emitting
Laser) devices, which offer improved speed, power and spectral properties, at a similar cost.
Common VCSEL devices couple well to multi mode fiber.
A semiconductor laser emits light through stimulated emission rather than spontaneous
emission, which results in high output power (~100 mW) as well as other benefits related to
the nature of coherent light. The output of a laser is relatively directional, allowing high
coupling efficiency (~50 %) into single-mode fiber. The narrow spectral width also allows for
high bit rates since it reduces the effect of chromatic dispersion. Furthermore, semiconductor
lasers can be modulated directly at high frequencies because of short recombination time.
Commonly used classes of semiconductor laser transmitters used in fiber optics
include VCSEL (Vertical Cavity Surface Emitting Laser), Fabry–Pérot and DFB (Distributed
Feed Back).
Laser diodes are often directly modulated, that is the light output is controlled by a current
applied directly to the device. For very high data rates or very long distance links, a laser
source may be operated continuous wave, and the light modulated by an external device such
as an electro-absorption modulator or Mach–Zehnder interferometer. External modulation
increases the achievable link distance by eliminating laser chirp, which broadens
the linewidth of directly-modulated lasers, increasing the chromatic dispersion in the fiber.
Receivers
The main component of an optical receiver is a photodetector, which converts light into
electricity using the photoelectric effect. The photodetector is typically a semiconductor-
based photodiode. Several types of photodiodes include p-n photodiodes, a p-i-n photodiodes,
and avalanche photodiodes. Metal-semiconductor-metal (MSM) photodetectors are also used
due to their suitability for circuit integration in regenerators and wavelength-division
multiplexers.
Optical-electrical converters are typically coupled with a transimpedance amplifier and
a limiting amplifier to produce a digital signal in the electrical domain from the incoming
optical signal, which may be attenuated and distorted while passing through the channel.
Further signal processing such as clock recovery from data (CDR) performed by a phase-
locked loop may also be applied before the data is passed on.
Fiber cable types
An optical fiber consists of a core, cladding, and a buffer (a protective outer coating), in
which the cladding guides the light along the core by using the method of total internal
reflection. The core and the cladding (which has a lower-refractive-index) are usually made
of high-quality silica glass, although they can both be made of plastic as well. Connecting
two optical fibers is done by fusion splicing or mechanical splicing and requires special skills
and interconnection technology due to the microscopic precision required to align the fiber
cores.
Two main types of optical fiber used in optic communications include multi-mode optical
fibers and single-mode optical fibers. A multi-mode optical fiber has a larger core (≥
50 micrometres), allowing less precise, cheaper transmitters and receivers to connect to it as
well as cheaper connectors. However, a multi-mode fiber introduces multimode distortion,
which often limits the bandwidth and length of the link. Furthermore, because of its
higher dopant content, multi-mode fibers are usually expensive and exhibit higher
attenuation. The core of a single-mode fiber is smaller (<10 micrometres) and requires more
expensive components and interconnection methods, but allows much longer, higher-
performance links.
In order to package fiber into a commercially-viable product, it is typically protectively-
coated by using ultraviolet (UV), light-cured acrylate polymers, then terminated with optical
fiber connectors, and finally assembled into a cable. After that, it can be laid in the ground
and then run through the walls of a building and deployed aerially in a manner similar to
copper cables. These fibers require less maintenance than common twisted pair wires, once
they are deployed.
Specialized cables are used for long distance subsea data transmission, e.g. transatlantic
communications cable. New (2011-2013) cables operated by commercial enterprises
(Emerald Atlantis, Hibernia Atlantic) typically have four strands of fibre and cross the
Atlantic (NYC-London) in 60-70ms. Cost of each such cable was about $300M in 2011.
Another common practice is to bundle many fibre optic strands within long-distance power
transmission cable. This exploits power transmission rights of way effectively, ensures a
power company can own and control the fibre required to monitor its own devices and lines,
is effectively immune to tampering, and simplifies the deployment of smart grid technology.
Amplifiers
The transmission distance of a fiber-optic communication system has traditionally been
limited by fiber attenuation and by fiber distortion. By using opto-electronic repeaters, these
problems have been eliminated. These repeaters convert the signal into an electrical signal,
and then use a transmitter to send the signal again at a higher intensity than it was before.
Because of the high complexity with modern wavelength-division multiplexed signals
(including the fact that they had to be installed about once every 20 km), the cost of these
repeaters is very high.
An alternative approach is to use an optical amplifier, which amplifies the optical signal
directly without having to convert the signal into the electrical domain. It is made by doping a
length of fiber with the rare-earth mineral erbium, and pumping it with light from a laser with
a shorter wavelength than the communications signal (typically 980 nm). Amplifiers have
largely replaced repeaters in new installations.
Plesiochronous Digital Hierarchy
The Plesiochronous Digital Hierarchy (PDH) is a technology used in telecommunications
networks to transport large quantities of data over digital transport equipment such as fibre
optic and microwave radio systems. The term plesiochronous is derived from Greek plēsios,
meaning near, and chronos, time, and refers to the fact that PDH networks run in a state
where different parts of the network are nearly, but not quite perfectly, synchronised.
PDH is typically being replaced by Synchronous Digital Hierarchy (SDH) or Synchronous
optical networking (SONET) equipment in most telecommunications networks.
PDH allows transmission of data streams that are nominally running at the same rate, but
allowing some variation on the speed around a nominal rate. By analogy, any two watches
are nominally running at the same rate, clocking up 60 seconds every minute. However, there
is no link between watches to guarantee they run at exactly the same rate, and it is highly
likely that one is running slightly faster than the other.
Implementation
The basic data transfer rate is a data stream of 2048 kbit/s. For speech transmission, this is
broken down into thirty 64 kbit/s channels plus two 64 kbit/s channels used for signalling and
synchronisation. Alternatively, the entire bandwidth may be used for non-speech purposes,
for example, data transmission.
The data rate is controlled by a clock in the equipment generating the data. The rate is
allowed to vary by ±50 ppm of 2.048 Mbit/s. This means that different data streams can be
(probably are) running at slightly different rates to one another.
In order to move multiple data streams from one place to another, they are multiplexed in
groups of four. This is done by taking 1 bit from stream #1, followed by 1 bit from stream #2,
then #3, then #4. The transmitting multiplexer also adds additional bits in order to allow the
far end receiving multiplexer to decode which bits belong to which data stream, and so
correctly reconstitute the original data streams. These additional bits are called "justification"
or "stuffing" bits.
Because each of the four data streams is not necessarily running at the same rate, some
compensation has to be introduced. The transmitting multiplexer combines the four data
streams assuming that they are running at their maximum allowed rate. This means that
occasionally, (unless the 2 Mbit/s really is running at the maximum rate) the multiplexer will
look for the next bit but it will not have arrived. In this case, the multiplexer signals to the
receiving multiplexer that a bit is "missing". This allows the receiving multiplexer to
correctly reconstruct the original data for each of the four 2 Mbit/s data streams, and at the
correct, different, plesiochronous rates.
The resulting data stream from the above process runs at 8,448 kbit/s (about 8 Mbit/s).
Similar techniques are used to combine four × 8 Mbit/s together, plus bit stuffing, giving
34 Mbit/s. Four × 34 Mbit/s, gives 140. Four × 140 gives 565.
565 Mbit/s is the rate typically used to transmit data over a fibre optic system for long
distance transport. Recently, telecommunications companies have been replacing their PDH
equipment with SDH equipment capable of much higher transmission rates. 2.048 Mbit/s
8.448 Mbit/s 34.368 Mbit/s 139.264 Mbit/s Multiplex levels
Synchronous digital hierarchy
Synchronous optical networking (SONET) and synchronous digital hierarchy (SDH) are
standardized multiplexing protocols that transfer multiple digital bit streams over optical
fiber using lasers or light-emitting diodes (LEDs). Lower data rates can also be transferred
via an electrical interface. The method was developed to replace the Plesiochronous Digital
Hierarchy (PDH) system for transporting larger amounts of telephone calls and data traffic
over the same fiber without synchronization problems. SONET generic criteria are detailed
in Telcordia Technologies Generic Requirements document GR-253-CORE. Generic criteria
applicable to SONET and other transmission systems (e.g., asynchronous fiber optic systems
or digital radio systems) are found in Telcordia GR-499-CORE.
SONET and SDH, which are essentially the same, were originally designed to
transport circuit mode communications (e.g., DS1, DS3) from a variety of different sources,
but they were primarily designed to support real-time, uncompressed, circuit-switched voice
encoded in PCM format. The primary difficulty in doing this prior to SONET/SDH was that
the synchronization sources of these various circuits were different. This meant that each
circuit was actually operating at a slightly different rate and with different phase.
SONET/SDH allowed for the simultaneous transport of many different circuits of differing
origin within a single framing protocol. SONET/SDH is not itself a communications
protocol per se, but a transport protocol.
Due to SONET/SDH's essential protocol neutrality and transport-oriented features,
SONET/SDH was the obvious choice for transporting Asynchronous Transfer Mode (ATM)
frames. It quickly evolved mapping structures and concatenated payload containers to
transport ATM connections. In other words, for ATM (and eventually other protocols such
as Ethernet), the internal complex structure previously used to transport circuit-oriented
connections was removed and replaced with a large and concatenated frame (such as OC-3c)
into which ATM cells, IP packets, or Ethernet frames are placed.
Difference from PDH
Synchronous networking differs from Plesiochronous Digital Hierarchy (PDH) in that the exact rates
that are used to transport the data on SONET/SDH are tightly synchronized across the entire network,
using atomic clocks. This synchronization system allows entire inter-country networks to operate
synchronously, greatly reducing the amount of buffering required between elements in the network.
Both SONET and SDH can be used to encapsulate earlier digital transmission standards, such as the
PDH standard, or they can be used to directly support either Asynchronous Transfer Mode (ATM) or
so-called packet over SONET/SDH(POS) networking. As such, it is inaccurate to think of SDH or
SONET as communications protocols in and of themselves; they are generic, all-purpose transport
containers for moving both voice and data. The basic format of a SONET/SDH signal allows it to carry
many different services in its virtual container (VC), because it is bandwidth-flexible.
The basic unit of transmission
The basic unit of framing in SDH is a STM-1 (Synchronous Transport Module, level 1),
which operates at 155.52 megabits per second (Mbit/s). SONET refers to this basic unit as an
STS-3c (Synchronous Transport Signal 3, concatenated) or OC-3c, depending on whether the
signal is carried electrically (STS) or optically (OC), but its high-level functionality, frame
size, and bit-rate are the same as STM-1.
SONET offers an additional basic unit of transmission, the STS-1 (Synchronous Transport
Signal 1) or OC-1, operating at 51.84 Mbit/s—exactly one third of an STM-1/STS-3c/OC-3c
carrier. This speed is dictated by the bandwidth requirements for PCM-encoded telephonic
voice signals: at this rate, an STS-1/OC-1 circuit can carry the bandwidth equivalent of a
standard DS-3 channel, which can carry 672 64-kbit/s voice channels. In SONET, the STS-
3c/OC-3c signal is composed of three multiplexed STS-1 signals; the STS-3C/OC-3c may be
carried on an OC-3 signal. Some manufacturers also support the SDH equivalent of the STS-
1/OC-1, known as STM-0.
Framing
In packet-oriented data transmission, such as Ethernet, a packet frame usually consists of
a header and a payload. The header is transmitted first, followed by the payload (and possibly
a trailer, such as a CRC). In synchronous optical networking, this is modified slightly. The
header is termed the overhead, and instead of being transmitted before the payload, is
interleaved with it during transmission. Part of the overhead is transmitted, then part of the
payload, then the next part of the overhead, then the next part of the payload, until the entire
frame has been transmitted.
In the case of an STS-1, the frame is 810 octets in size, while the STM-1/STS-3c frame is
2,430 octets in size. For STS-1, the frame is transmitted as three octets of overhead, followed
by 87 octets of payload. This is repeated nine times, until 810 octets have been transmitted,
taking 125 µs. In the case of an STS-3c/STM-1, which operates three times faster than an
STS-1, nine octets of overhead are transmitted, followed by 261 octets of payload. This is
also repeated nine times until 2,430 octets have been transmitted, also taking 125 µs. For both
SONET and SDH, this is often represented by displaying the frame graphically: as a block of
90 columns and nine rows for STS-1, and 270 columns and nine rows for STM1/STS-3c.
This representation aligns all the overhead columns, so the overhead appears as a contiguous
block, as does the payload.
The internal structure of the overhead and payload within the frame differs slightly between
SONET and SDH, and different terms are used in the standards to describe these structures.
Their standards are extremely similar in implementation, making it easy to interoperate
between SDH and SONET at any given bandwidth.
In practice, the terms STS-1 and OC-1 are sometimes used interchangeably, though the OC
designation refers to the signal in its optical form. It is therefore incorrect to say that an OC-3
contains 3 OC-1s: an OC-3 can be said to contain 3 STS-1s.
SDH frame
An STM-1 frame. The first nine columns contain the overhead and the pointers. For the sake
of simplicity, the frame is shown as a rectangular structure of 270 columns and nine rows but
the protocol does not transmit the bytes in this order.
For the sake of simplicity, the frame is shown as a rectangular structure of 270 columns and
nine rows. The first three rows and nine columns contain regenerator section overhead
(RSOH) and the last five rows and nine columns contain multiplex section overhead
(MSOH). The fourth row from the top contains pointers.
The STM-1 (Synchronous Transport Module, level 1) frame is the basic transmission format
for SDH—the first level of the synchronous digital hierarchy. The STM-1 frame is
transmitted in exactly 125 µs, therefore, there are 8,000 frames per second on a 155.52 Mbit/s
OC-3 fiber-optic circuit. The STM-1 frame consists of overhead and pointers plus
information payload. The first nine columns of each frame make up the Section Overhead
and Administrative Unit Pointers, and the last 261 columns make up the Information Payload.
The pointers (H1, H2, H3 bytes) identify administrative units (AU) within the information
payload. Thus, an OC-3 circuit can carry 150.336 Mbit/s of payload, after accounting for the
overhead.
Carried within the information payload, which has its own frame structure of nine rows and
261 columns, are administrative units identified by pointers. Also within the administrative
unit are one or more virtual containers (VCs). VCs contain path overhead and VC payload.
The first column is for path overhead; it is followed by the payload container, which can
itself carry other containers. Administrative units can have any phase alignment within the
STM frame, and this alignment is indicated by the pointer in row four.
The section overhead (SOH) of a STM-1 signal is divided into two parts: the regenerator
section overhead (RSOH) and the multiplex section overhead (MSOH). The overheads
contain information from the transmission system itself, which is used for a wide range of
management functions, such as monitoring transmission quality, detecting failures, managing
alarms, data communication channels, service channels, etc.
The STM frame is continuous and is transmitted in a serial fashion: byte-by-byte, row-by-
row.
Transport overhead
The transport overhead is used for signaling and measuring transmission error rates, and is
composed as follows:
Section overhead
Called RSOH (regenerator section overhead) in SDH terminology: 27 octets
containing information about the frame structure required by the terminal equipment.
Line overhead
Called MSOH (multiplex section overhead) in SDH: 45 octets containing information
about error correction and Automatic Protection Switching messages (e.g., alarms and
maintenance messages) as may be required within the network.
AU Pointer
Points to the location of the J1 byte in the payload (the first byte in the virtual
container).
Path virtual envelope
Data transmitted from end to end is referred to as path data. It is composed of
two components:
Payload overhead (POH)
Nine octets used for end-to-end signaling and error measurement.
Payload
User data (774 bytes for STM-0/STS-1, or 2,340 octets for STM-1/STS-3c)
For STS-1, the payload is referred to as the synchronous payload envelope (SPE), which in
turn has 18 stuffing bytes, leading to the STS-1 payload capacity of 756 bytes.
The STS-1 payload is designed to carry a full PDH DS3 frame. When the DS3 enters a
SONET network, path overhead is added, and that SONET network element (NE) is said to
be a path generator and terminator. The SONET NE is line terminating if it processes the
line overhead. Note that wherever the line or path is terminated, the section is terminated
also. SONET regenerators terminate the section, but not the paths or line.
An STS-1 payload can also be subdivided into seven virtual tributary groups (VTGs). Each
VTG can then be subdivided into four VT1.5 signals, each of which can carry a
PDH DS1 signal. A VTG may instead be subdivided into three VT2 signals, each of which
can carry a PDH E1 signal. The SDH equivalent of a VTG is a TUG2; VT1.5 is equivalent
to VC11, and VT2 is equivalent to VC12.
Three STS-1 signals may be multiplexed by time-division multiplexing to form the next level
of the SONET hierarchy, the OC-3 (STS-3), running at 155.52 Mbit/s. The signal is
multiplexed by interleaving the bytes of the three STS-1 frames to form the STS-3 frame,
containing 2,430 bytes and transmitted in 125 µs.
Higher-speed circuits are formed by successively aggregating multiples of slower circuits,
their speed always being immediately apparent from their designation. For example, four
STS-3 or AU4 signals can be aggregated to form a 622.08 Mbit/s signal designated OC-
12 or STM-4.
The highest rate commonly deployed is the OC-768 or STM-256 circuit, which operates at
rate of just under 38.5 Gbit/s. Where fiber exhaustion is a concern, multiple SONET signals
can be transported over multiple wavelengths on a single fiber pair by means of wavelength-
division multiplexing, including dense wavelength-division multiplexing (DWDM) and
coarse wavelength-division multiplexing (CWDM). DWDM circuits are the basis for all
modern submarine communications cable systems and other long-haul circuits.