Six Months Industrial Training Report

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).

http://en.wikipedia.org/wiki/File:Generation_of_CDMA.svg

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.

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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.

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1 BTS CabinetAirbridge BTS3900 CDMA Base Station

Hardware Description

Figure 1-3 Typical configuration of the BTS3900 cabinet


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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.


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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.


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.


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2 BTS ComponentsAirbridge BTS3900 CDMA Base Station



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.


Appearance of the BBU3900

Figure 2-1 shows the BBU3900.


2-3


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.


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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


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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.


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(1) ETH port (2) FE0 port (3) FE1 port (4) USB port

(5) TEST port (6) E1/T1 port (7) GPS port



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


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.


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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.


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Indicato

Color Meaning Description Normalr State

RX Green Port Optical port Onindicator l ON: The optical transmission is

normal and the connection is normal.


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.


2-9


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


2.1.3.1 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.


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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.


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.



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Indic ator


ALM Red Alarm indicator

l

l

ON: The board must be replaced.

Blinking at 4 Hz: A critical alarm is

OFF

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.


Optical port ON



Electrical port



RX Green Port indicator

Optical port ON



Electrical port



Technical Specifications of the HCPM

This describes the technical specifications of the HCPM.

The technical specifications of the HCPM are as follows:


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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 Channel processing capacity: 285 forward channels and 256 reverse channels


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


Ports

Table 2-7 lists the ports on the HECM panel.


2-13


Table 2-7 Ports on the HECM panel

Port Description





Indicators

Table 2-8 lists the indicators on the HECM panel.


Indic ator




l Blinking at 0.5 Hz: The board functions properly.


Blinking at0.5 Hz


l ON: The board must be replaced.





OFF

ACT Green Operation indicator

l On: The board functions properly. ON





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Indic Color Meaning

Description Normalator State

TX Green Port Optical port ONindicator l ON: The optical transmission is normal

and the connection is normal.


Electrical port





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Optical port ON



Electrical port



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).


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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.


1-3


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.


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Figure 1-3 Typical configuration of the BTS3900 cabinet


1-5


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


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.


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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.


2-1


2 BTS

Components

About This Chapter

The components of the BTS3900 cabinet include the BBU3900, CRFU, DCDU-01, SLPU (optional) and FAN.


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.


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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.



2.1.5 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.


Appearance of the BBU3900

Figure 2-1 shows the BBU3900.


2-3


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


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.


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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


2-5


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.


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(1) ETH port (2) FE0 port (3) FE1 port (4) USB port

(5) TEST port (6) E1/T1 port (7) GPS port



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


Electric port, supporting electric cable


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.


2-7



Indicato r


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.


ALM Red Alarm l ON: The board must be replaced. Offindicator




l Off: No alarm is generated.

ACT Green Active/ l ON: The active board is used. -standbyindicator

l OFF: The standby board is used.


Optical port On



Electrical port




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Indicato

Color Meaning Description Normalr State

RX Green Port Optical port Onindicator l ON: The optical transmission is

normal and the connection is normal.


Electrical port



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.


2-9


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.]




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.


Issue 03 (2008-12-25)



Exterior

Figure 2-5 shows the HCPM panel.

Figure 2-5 HCPM panel


Ports

Table 2-5 lists the ports on the HCPM panel.

Table 2-5 Ports on the HCPM panel

Port Description





Indicators

Table 2-6 lists the indicators on the HCPM panel.


Indic ator

Color Meaning

Description NormalState



Blinking at0.5 Hz

l Blinking at 0.5 Hz: The board functionsproperly.



2-11


Indic ator



l

l

ON: The board must be replaced.

Blinking at 4 Hz: A critical alarm is

OFF

generated.




ACT Green Operation l On: The board functions properly. ONindicator





Optical port ON



Electrical port




Optical port ON



Electrical port



Technical Specifications of the HCPM

This describes the technical specifications of the HCPM.

The technical specifications of the HCPM are as follows:


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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 Channel processing capacity: 285 forward channels and 256 reverse channels


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


Ports

Table 2-7 lists the ports on the HECM panel.


Table 2-7 Ports on the HECM panel

Port Description





Indicators

Table 2-8 lists the indicators on the HECM panel.


Indic ator




l Blinking at 0.5 Hz: The board functions properly.


Blinking at0.5 Hz


l ON: The board must be replaced.





OFF

ACT Green Operation indicator

l On: The board functions properly. ON




Indic Color Meaning

Description Normalator State

TX Green Port Optical port ONindicator l ON: The optical transmission is normal

and the connection is normal.


Electrical port




Optical port ON



Electrical port



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.

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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.

http://en.wikipedia.org/wiki/File:SDH_STM1_Frame.svg

http://en.wikipedia.org/wiki/File:SDH_STM1_Frame.svg

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http://en.wikipedia.org/wiki/File:Stm_1.jpg

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.

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