RF COURSE CONTENTSCDMA Drive Test in 5 important parameters
worth to see1)TXPOWER 2)RXPOWER 3)Ec/Io 4)TXADJ 5)FER. 1.EcIo EcIo
reflects the handset in the current received pilot signal level.
This is an integrated pilot signal. Why, because mobile phones are
a multi-channel soft switching, which translates into mobile phones
often lies in more than one pilot overlapping coverage area, the
level of the phone, EcIo reflects the phone at this point that a
multi-channel pilot signal level of the overall coverage. We know
that the Ec is a mobile phone available pilot signal strength, and
Io is the mobile phone receives all the strength of the signal.
Therefore, EcIo reflects the available signal strength in occupies
all signals. The higher the value, the greater the proportion of a
useful signal, on the other hand also reversed. At some point EcIo
big, there are two possibilities. First, the Ec is very large,
dominant level here, Ec, Io is very small, that is to say here is
from another base station's messy little pilot signal, EcIo also
larger. In the latter case is weak, because the Ec small, Io is
also small, so small, so RSSI also there may be dropped. At some
point EcIo also small, there are two possible, first, the Ec is
also small small RSSI, this is the weak coverage area. The Ec is
not small, RSSI, this illustrates the Io is the overall intensity
of the signal is not bad. This situation is often a BSC switch data
configuration, no nearby strong pilot signal into the adjacent
community table, so the phone doesn't recognize the strong pilot
signal in the vicinity as a jamming signal processing. On the road,
in the case of a typical phenomenon is the phone in a move to
maintain certain RSSI, EcIo level, rapid rise to FER and eventually
dropped. 2 TXPOWER TXPOWER is the phone's transmitter power. We
know that power control is guaranteed call quality and address the
CDMA community interference tolerance and one of the key means of
mobile phone from the base station near, uplink quality good, the
mobile phone transmitting power is smaller, because at the base
station is able to guarantee the reception of the signal to launch
mobile phone and fer also small and mobile phones transmitting
power is smaller to other mobile phones in the community is also a
small interference. So mobile phones transmit power level,
reflecting the handset's current uplink loss and interference.
Uplink loss of large, or there is serious interference with the
phone's transmitter power will be greatly missed mobile phone
transmitting power is smaller. Roadtest, in normal circumstances,
the more closer to the base station or Repeater, the mobile phone
transmitting power is reduced, away from the base station and
Repeater, the mobile phone transmitting power increases. If the
base station and Repeater nearby mobile phone transmitting power,
obviously it is not normal. Perhaps there is interference, the
uplink can be a base station and Repeater itself. Such as community
antenna wrong receive carrier frequency amplifier circuit problems,
etc. If the Repeater nearby, cell phone transmitter power, it may
be a Repeater malfunctions, uplink gain set too small, and so
on.Above you can
see, the road of TXPOWER level reflects the base station
coverage area of reverse link quality and uplink interference
levels. 3RXPOWER RXPOWER is a mobile phone to receive power. In
CDMA, according to my personal understanding, there are three
parameters is very close by, you can almost equivalent to the use
of parameters. Namely RXPOWER, RSSI, Io. RXPOWER is a mobile phone
to receive power, Io is mobile phones currently receives all signal
strength, RSSI is receives downlink band of total power, as
currently I have access to information, the title explains, but
understanding is very similar, is the phone receives a total of
signal strength. RXPOWER and reflects the current signal receiving
phone, RXPOWER small area, the weak positive fall within the
coverage area, RXPOWER places belong to the covered area. But the
high places, RXPOWER and does not necessarily signal quality is
good, because there may be no signal, leading to frequency, or too
many strong pilot, pilot frequency pollution. Therefore, the
analysis of RXPOWER to EcIo to analysis.Above you can see, RXPOWER
and simply reflects the drive test signal coverage area, rather
than the quality of the signal coverage. 4TXADJ TXADJ reflects the
up and down-link a balance. Note that this value is calculated from
the measurement, instead. 800M CDMA system is Tx_adjust = 73dB +
Tx_power + Rx_power, 1900M CDMA is Tx_adjust = 76dB + Tx_power +
Rx_power. TXADJ reflects the current location of the mobile uplink
and downlink of a more mass. We know that under normal
circumstances, the cell phone away from the base station close to
the phone's transmitter power will decrease, and received power
will become larger and far away from the cell phone, mobile phone
base station transmitter power will increase while receiving power
gets smaller. Normally, the transmitter power and receiver power
plus a constant fixed values, the result should be a small interval
(for example,-10 to + 10). If TXADJ great, it means that the
phone's transmitter power, receive the power, then it is obvious
that mobile current downlink of good quality (receiving power), and
the poor quality of the uplink (transmitter power), this time
forward link is better than a reverse link. On the contrary, TXADJ
is very small, explains this reverse link well to the forward link.
We know that the base station coverage depends on the reverse link
loss level. Therefore, in General, we require the following TXADJ
in 0. But greater than 10, the reverse link forward link than are
poor, the situation is not ideal. For TXADJ, nor can they be said
to be as small as possible. But in the actual drive test, we
generally encounter, often TXADJ too high, forward link, reverse
link. 5 FER FER is a forward-fer. Forward fer with EcIo also is a
comprehensive quality of forward link. Because when the phone is in
the multi-channel soft switching, fer actually multi-channel
forward an integrated signal quality. FER, description of the
mobile phone of the forward link better, received signal is good,
this time EcIo also should be better. The larger the Description
cell phone FER the received signal strength is poor, EcIo should
also at this time. FER is large, it may also be due to a
neighboring community switch parameter configuration error. If you
switch between adjacent community with leakage, single and mobile
to mobile, adjacent to the pilot was not recognized, and the pilot
does not recognize, it will become interference signal, resulting
in increased FER. In reality, often manifested in mobile, mobile
phones, FER a rapid rise in sharp decline, EcIo, and finally
dropped.Above that is closely followed by EcIo FER. FER reflects
the call quality is good or bad, reflects the RoadTest
regional coverage quality level, rather than the signal coverage
strength level. In some areas although belonging to the weak signal
coverage area, but relatively clean (messy signals, noise), as well
as be good FER. Note the above parameters, EcIo, RXPOWER is the
phone in standby or call have parameters, TXPOWER, TXADJ, FER is
only a phone call and from the only parameter. The above five
parameters, together, to analysis of drive test region to cover the
intensity level, the former to override the quality level, as well
as the reverse link loss level, and so on, is the analysis of drive
test is the most important parameters. In-depth understanding of
the five parameters, combined with the overall situation for drive
testing specific analysis, is engaged in network optimization staff
in one of the basic conditions.
CDMA Drive Test- 5 Important Parameters worth to see 1)TXPOWER
2)RXPOWER 3)Ec/Io 4)TXADJ 5)FER. For more detail About Click Here
1.EcIo EcIo reflects the handset in the current received pilot
signal level. This is an integrated pilot signal. Why, because
mobile phones are a multi-channel soft switching, whichtranslates
into mobile phones often lies in more than one pilot overlapping
coverage area, the level of the phone, EcIo reflects the phone at
this point that a multi-channel pilotsignal level of the overall
coverage. 2 TXPOWER TXPOWER is the phone's transmitter power. We
know that power control is guaranteed call quality and address the
CDMA community interference tolerance and one of the key means of
mobile phone from the base station near, uplink quality good, the
mobile phone transmitting power is smaller, because at the base
station is able to guarantee the reception of the signal to launch
mobile phone and fer also small and mobile phones transmitting
power is smaller to other mobile phones in the community is also a
small interference. 3RXPOWER RXPOWER is a mobile phone to receive
power. In CDMA, according to my personal understanding, there are
three parameters is very close by, you can almost equivalent to the
use of parameters.
Module-AIntroduction to Radio
waves.........................................................................................................
1 Cell site, Introduction & classification of cell site 1
Different types of Telecom Towers & Shelters 6 RF Cables &
RF Connectors. 9 Introduction to Antenna, Antenna Properties of
Antenna, Antenna Gain Antenna Tilt, Mechanical & Electrical
Tilt
Module A: Fundamental of Radio FrequencyThe term "RF waves"
typically refers to radio frequency waves, a form of
electromagnetic energy invisible to the human eye. Radio frequency
communication is virtually omnipresent in the modern world, used
for everything from automobile radios to computers. Radio frequency
(RF) is a rate of oscillation in the range of about 3 kHz to 300
GHz, which corresponds to the frequency of radio waves, and the
alternating currents which carry radio signals. RF waves travel at
the speed of light, and are also emitted by natural sources
including stars. Radio frequency (RF) energy has been used in
medical treatments for over 75 years, generally for minimally
invasive surgeries, using radiofrequency ablation and cryoablation,
including the treatment of sleep apnea. Magnetic resonance imaging
(MRI) uses radio frequency waves to generate images of the human
body.CELL: A cell is the basic geographic unit of a cellular system
and is defined as by one BS antenna system. the area of radio
coverage given
Classification of cells in GSM Network: Large Cells: Large cells
are employed in 1. Remote areas. 2. Coastal regions. 3. Areas with
few subscribers. 4. Large areas which need to be covered with the
minimum number of cell sites
SMALL CELLS or MICRO CELLS: Urban areas. Low transmission power
required. High number of MSs. However, micro cells are cells where
the antenna height is under the average roof top level and they are
typically used in urban areas
Pico Cells: The Pico cells are small cells whose diameter is a
few dozen meters and are mainly used indoors.
Umbrella Cells: Umbrella cells are used to cover shadow regions
of smaller cells and fill in gaps of coverage between those cells.
These cells are usually built on high ways to cover the uncovered
region. A Cluster is a group of cells. No channels are reused
within a cluster. If a cluster has 3 cells, it is called 3 cell
cluster, if a cluster has 4 cells, it is called 4 cell cluster, and
if it is 7 cells, it is called 7 cell cluster.
Telecommunication Towers:
Telecommunication towers are used for communication purposes
among people. All the wireless communication, mobile networking,
radio broadcasting and television antennas are connected via these
towers. A full telecommunication tower is a whole set of mechanical
structures and electronic signal processing unit which is used to
connect people via telecommunications. All the telephone lines and
mobile phone services are connected through these towers. These
towers are also used for radar system and other armed forces
purposes. Different heights of towers are used in different places
and purposes. They can vary from 15 to 60 meters and some time more
if required. For example in the land areas towers are higher in
hill area so 15 to 30 meters high towers can be used but in land
areas they are 30 to 60 meters in height. There are different types
of the telecommunication towers which are used i.e. monopole, self
supporting and guyed etc. The most used are the self supporting
towers in the field of telecommunication, which is the
specialization of final project and thesis as well. Based on
structural action.Towers are classified into three major groups
based on the structural action. They are: Self supporting towers
Guyed towers Monopole.
Self supporting towers.
The towers that are supported on ground or on buildings are
called as self-supporting towers. Though the weight of these towers
is more they require less base area and are suitable in many
situations. Most of the TV, MW, Power transmission, and flood light
towers are self-supporting towers. Guyed towers. Guyed towers
provide height at a much lower material cost than self-supporting
towers due to the efficient use of high-strength steel in the guys.
Guyed towers are normally guyed in three directions over an anchor
radius of typically 2/3 of the tower height and have a triangular
lattice section for the central mast. Tubular masts are also used,
especially where icing is very heavy and lattice sections would ice
up fully. These towers are much lighter than self- Design of Steel
Structures. Whenever large open space is available, guyed towers
can be provided. There are other restrictions to mount dish
antennae on these towers and require large anchor blocks to hold
the ropes. Monopole It is single self-supporting pole, and is
generally placed over roofs of high raised buildings, when number
of antennae required is less or height of tower required is less
than 9m. Based on cross section of tower Towers can be classified,
based on their cross section, into square, rectangular, triangular,
delta, hexagonal and polygonal towers. Open steel lattice towers
make the most efficient use of material and enable the construction
of extremely light-weight and stiff structures by offering less
exposed area to wind loads. Most of the power transmission,
telecommunication and broadcasting towers are lattice towers.
Triangular Lattice Towers have less weight but offer less stiffness
in torsion. With the increase in number of faces, it is observed
that weight of tower increases. The increase is 10% and 20% for
square and hexagonal
cross sections respectively. If the supporting action of
adjacent beams is considered, the expenditure incurred for
hexagonal towers is somewhat less Based on the type of material
sections Based on the sections used for fabrication, towers are
classified into angular and hybrid towers (with tubular and angle
bracings). Lattice towers are usually made of bolted angles.
Tubular legs and bracings can be economic, especially when the
stresses are low enough to allow relatively simple connections.
Towers with tubular members may be less than half the weight of
angle towers because of the reduced wind load on circular sections.
However the extra cost of the tube
and the more complicated connection details can exceed the
saving of steel weight and foundations. Based on the placement of
tower Based on this placement, Communication towers are classified
as follows: Green Field Tower Roof Top Tower Erection Erected on
natural ground with suitable foundation Erected on existing
building with raised columns and tie beams. Height 30 200 m 9 30
usual Location Rural Areas Urban Areas Economy Less More Based on
the number of segments: The towers are classified based on the
number of segments as three slope tower; two slope tower; Single
slope tower; Straight tower.
Telecom Shelter: Shelter or cabinet means a cabinet or building
used by telecommunication providers tohouse equipment at a
facility.
RF Cable & RF Connectors:
ANTENNA: An antenna is a specialized transducer that converts
radio-frequency (RF) fields into alternating current (AC) or
vice-versa. There are two basic types: the receiving antenna, which
intercepts RF energy and delivers AC to electronic equipment, and
the transmitting antenna, which is fed with AC from electronic
equipment and generates an RF field.
Directional antenna Antenna having a preference for a particular
direction and radiating (receiving) a signal more efficiently in
(from) this direction than in other directions.
Isotropic antenna Antenna transmitting (receiving) equal
radiation in (from) all directions. Isotropic antenna is a
idealized device that does not exist in reality. It is usually
taken as a reference when measuring directivity of actual antennas.
Omni directional antenna: Antenna transmitting (receiving) equal
radiation in (from) all directions. A typical example is a whip
antenna. Whip antenna's radiation power is distributed equally in
all directions in a plane perpendicular to the whip.
The Yagi antenna: The Yagi antenna or more correctly, the Yagi -
Uda antenna was developed by Japanese scientists in the 1930's. It
consists of a half wave dipole, a rear "reflector" and may or may
not have one or more forward "directors". These are collectively
referred to as the "elements of Yagi Antenna.
Parabolic antenna: The parabolic antenna is a high-gain
reflector antenna used for radio, television and data
communications, and also for radio location (RADAR), on the UHF and
SHF parts of the electromagnetic spectrum. The relatively short
wavelength of electromagnetic (radio) energy at these frequencies
allows reasonably sized reflectors to exhibit the very desirable
highly directional response for both receiving and
transmitting.
RADITION PATTERN: A radiation pattern is a plot of electric
field intensity, at a fixed distance, as a function of direction
from the antenna or antenna array. Although radiation patterns [can
be] determined mathematically, it is possible to obtain patterns by
taking actual field measurements.
ANTENNA GAIN: Gain (G) = Maximum Radiation Intensity from
Antenna Maximum Radiation Intensity from Reference
ANTENNA TILT: Electrical Tilt: This is done with the help of
phase shifters.The phase of the feed(voltage) to the dipoles is
changed further leading to change in the radiation pattern in a
better manner. Mechanical Tilt: In this you bend the antenna
mechanically without any change in the internal ckt. The major lobe
will become heart shaped in case of larger tilts.
The efficiency of a cellular network depends of its correct
configuration and adjustment of radiant systems: their transmit and
receive antennas.And one of the more important system optimizations
task is based on correct adjusting tilts, or the inclination of the
antenna in relation to an axis. With the tilt, we direct
irradiation further down (or higher), concentrating the energy in
the new desired direction. When the antenna is tilted down, we call
it 'downtilt', which is the most common use. If the inclination is
up (very rare and extreme cases), we call 'uptilt'.
The tilt is used when we want to reduce interference and/or
coverage in some specific areas, having each cell to meet only its
designed area.
Module C: RF Survey( Radio Frequency Survey)RF survey is carried
out to find out suitable location for BTS cell site giving best
desired result on RF. RF Survey is done after the RF planning. RF
planning data is created based on indoor & outdoor coverage
criteria in the circle where mobile services are to be
provided.
RF survey is important because it gives visual details to RF
planner. Based on these details planner can create better model.
Two types of RF survey is conducted: a) Nominal Survey b) Hot Spot
Survey Tools used during the RF survey: a) GPS b) Digital Camera c)
Magnetic Compass d) Map Info Software e)Measuring Tape
f)Binocular
Important points to be checked during RF Survey:
a) Type of area- Residential/commercial b) Type of Population-
Income wise c) Any hilly areas or rivers or forest falling &
direction d) Type of buildings available e) Check for immediate
obstructions f) Check for coverage objectives RF site survey is
carried out in the following steps: Collect list of Nominals to be
surveyed, from the customer. In case of new town surveys where
Nominals are not provided, survey the town and provide a nominal
for suitable site location. Use the survey report template
forwarded by the customer. Identify physical location of the
proposed nominal and locate 3 candidates (maximum) for each
nominal, as per search ring size suggested by the customer. Survey
the site for RF suitability. Record Latitude and Longitude,
building height etc. of the proposed candidates.
LOS (Line of Sight): By definition, line of sight is the visual
line of sight that is determined by the ability of the average
human eye to resolve a distant object. Our eyes are sensitive to
light but optical wavelengths are very short compared to radio
wavelengths. Accurate radio transmission depends on a clear path
between radio antennas known as Line of Sight.
FRESNEL ZONE: Now the zone surrounding the RF LOS is said to be
the Fresnel zone. Fresnel zone named for physicist Augustine-Jean
Fresnel. To maximize receiver strength, one needs to minimize the
effect of the out-of-phase signals by removing obstacles from the
radio frequency line of sight (RF LOS). The strongest signals are
on the direct line between transmitter and receiver and always lie
in the first Fresnel zone.If unobstructed, radio waves will travel
in a straight line from the transmitter to the receiver. But if
there are obstacles near the path, the radio waves reflecting off
those objects may arrive out of phase with the signals that travel
directly and reduce the power of the received signal.
At the time of Calculating FZ radius we use frequency as given :
For 0 to 15 km distance we have to use 15Ghz More than 15km we have
to use 7Ghz frequency. But when u make calculation then we have put
frequency in Mhz..e.g-15 GHz=15*10^3*10^6 = 15*10^3Mh
Module C: 2G & 3G RF Drive TestMeans collecting data on
vehicle movement. Its variation has also intuitive: Walk Test,
i.e., collect data by walking areas of interest. a) Coverage area
b) Coverage Indoor & outdoor c) Speech Quality d)
Interference
e) Call drops in the network
The main types of Drive Test are : Performance Analysis
Benchmarking/Comparative Drive Test SCFT(Single Cell Functionality
Test)) Cluster Drive Test
There are many drive test tools in market which is used by us
for Drive Test. Drive Test Software tools are used by us:
TEMS(8.0.3,9,10,11,12)NEMO,PROBE,AGILENT DONGLE (Related tools)
MOBILE ( W995 FOR TEMS,U 120E FOR PROBE ETC) TESTING SIM OF
OPERATOR GPS 72,70 OR MOUSE GPS
Following is the procedure and parameters that need to checked
while performing Drive Test for a New Site. CPC (Cell Parameter
Check) MOC (Mobile Originated Calls) MTC (Mobile Terminated Calls
Prepaid to Postpaid) SMS (Short Messaging Service) GPRS Intra Site
Handover Inter Site Handover Idle Drive (Normal Drive &
Frequency Lock Drive) Dedicated Drive
Radio Parameters:
RxLev : Receiving level in terms of dBm that mobile is receiving
from the site. Range of -30 dBm to -110dBm. RxQual : Quality of
voice which is measured on basis of BER. Range of RxQual 0 -7. FER
: Frame Erasure Rate it represents the percentage of frames being
dropped due to high number of non-corrected bit errors in the
frame. It is indication of voice quality in network.
BER:-Ratio of the number of bit errors to the total number of
bits transmitted in a given time interval.
BER is a measure for the voice quality in network.. Depending on
BER RxQual is measured. E.g., BER 0 to 0.2 % corresponds to RxQual
0. Max. BER countable and useful is up to 12.8 % which corresponds
to RxQual of max. 7.
SQI : SQI is a more sophisticated measure which is dedicated to
reflecting the quality of the speech (as opposed to radio
environment conditions). This means that when optimizing the speech
quality in your network, SQI is the best criterion to use.
SQI is updated at 0.5 s intervals. It is computed on basis of
BER and FER. For EFR 30, FR 21 & HR 17 are respectively ideal
values.
C/I : The carrier-over-interference ratio is the ratio between
the signal strength of the current serving cell and the signal
strength of undesired (interfering) signal components. It should be
at least > 9 .
HANDOVER: Maintains Call Continuity. Controlled by BSS. Based on
RF subsystem criteria or traffic loading considerations. Both MS
and BTS provide RF link measurements to the handover process.
Handover Types: Within same Base Transceiver Station (Intra-BTS)
Between different BTSs served by same BSC (intra- BSS/inter-BTS)
Between different BSSs within same MSC (intra-MSC/inter-BSS)
Between different MSCs (inter-MSC)
INTERFERENCE Interference is nothing but the unwanted signal or
noise. EFFECTS OF INTERFERENCE a) Interference is a major factor
which affects network performance. b) It reduces the signal quality
in network. c) It makes bit errors in the received signal. d) The
up link and down link signal strength are affected by interference.
MAJOR SOURCES OF INTERFERENCE a) other user Equipment in the same
site. b) Nearer BTS on the same frequency. c) Due to environment
TYPES OF INTERFERENCE There are two types of interference
Co-channel interference Co-channel interference is caused
because of frequency reuse pattern (Different Sites using same set
of frequency. For minimizing the co-channel interference,
co-channel cells should be separated by a minimum distance and also
by set various frequencies.
Adjacent channel interference Adjacent channel interference is
caused by adjacent in frequency to the desired signal and also due
to imperfect receiver filters in mobile equipment. It can be
reduced by careful filtering and channel assignments.
3G Drive Test Procedure:
Radio Network Initial Tuning for WCDMA Preparations Parameter
Audit Drive Testing & Post Processing Analysis & Change
Proposals Change Verification & Reporting
Commercial Launch
WCDMA SERVING SET: Active Set (AS): The cells involved in soft
handover and measured by the UE.
Monitored Set (MN): The monitored set is created from the
neighbor cell lists of all the cells in the Active Set. The max
number of cells in each set is 32. Unmonitored set: cells excluded
from MN set because MN set is full. UE is not ordered to measure
them. Detected Set (DN) : The intra frequency cells detected by the
UE but not part of Active Set or monitored set. (Can then be an
Unmonitored or a Missing neighbor) PILOT Pollution: Simply
speaking, when the number of strong cells exceeds the active set
size, there is pilot pollution in the area. Typically the active
set size is 3, so if there are more than 3 strong cells then there
is pilot pollution. Definition of strong cell: pilots within the
handover window size from the strongest cell. Typical handover
window size is between 4 to 6dB. For example, if there are more
than 2 cells (besides the strongest cell) within 4dB of the
strongest cell then there is pilot pollution. CPICH RSCP: The CPICH
RSCP is the key measurement for DL coverage. The CPICH RSCP is an
RXLEV measurement. The CPICH RSCP (Received Signal Code Power) is
the received power on one code measured on CPICH. CPICH (Common
Pilot Channel) RSCPReceived power on one code measured on the pilot
bits of the primary CPICH. The reference point for the RSCP is the
antenna connector at the mobile station Range is for CPICH RSCP is
from 115dBm to -25 dBm. CPICH Ec/IoThe CPICH Ec /Io is the key
measurement for radio optimization for CDMA. The CPICH EC/I0
measures the soft radio capacity. This measurement is for: Cell
re-/selection DL open-loop power control Soft HO and
inter-frequency Hard HO
UE Tx Power:The UE TX power is the key measurement to analyze UL
coverage.
It is the only uplink measurement that is available at the UE
side. It is defined in the 3GPP TS25.215 as the total UE
transmitted power on one total UE transmitted power on one carrier
at the UE antenna connector. The reporting range for UE transmitted
power is from -50 dBm to 33 dBm
RSSI:RSSI-Received signal strength indicator, the wideband
received power within the relevant channel bandwidth. Measurement
shall be performed on downlink carrier. The reference point for the
RSSI is the antenna connector at the mobile station
SIR:Signal-to-interference ratio, defined as: (RSCP/ISCP)(SF/2),
where ISCP = interference signal code power, the interference on
the received signal Measured on the pilot bits. Only the no
orthogonal part of the interference is included in the measurement.
SF = the spreading factor used. The SIR shall be measured on DPCCH
after RL combination. The reference point for the SIR is the
antenna connector of the mobile station. HSDPA TESTING/HSUPA
TESTING:
Module D: RF Optimization & PlanningRF
Optimization:Optimization is an important step in the life cycle of
a wireless network. Drive testing is the first step in the process,
with the goal of collecting measurement data as a function of
location. Once the data has been collected over the desired RF
coverage area, it is output to post-processing software. Engineers
can use the collection and post-processing software to identify the
causes of RF coverage or interference problems and determine how
these problems can be solved. When the problems, causes and
solutions have been identified, steps are performed to solve the
problems. Network statistics are also an important step in analysis
and troubleshooting of RF issues. Analyzing daily and weekly basis
KPI trend for parameters like Call Setup Success Rate, Drop Call
Rate (DCR), Rx Quality & level, Handover Success Rate etc. and
resolve problem promptly. Analyzing & rectifying Neighbor
discrepancies, non-symmetrical Neighbor, adjacent Co-BISC, Co- CH
and Adj-CH neighbors. Responsible for Post processing of drive data
and implementing the changes with the help of ACTIX post processing
tool. Analysis of daily reports of OMCR and modification of
undeclared neighbor list for each Sector to maintain KPIs.
Optimization process can be explained by below step by step
description: Problem Analysis Analyzing performance retrieve tool
reports and statistics for the worst performing BSCs and/or Sites
Viewing Reports for BSC/Site performance trends Examining Planning
tool Coverage predictions Analyzing previous drive test data
Discussions with local engineers to prioritize problems Checking
Customer Complaints reported to local engineers
Checks Prior to Action:
Cluster definitions by investigating BSC borders, main cities,
freeways, major roads Investigating customer distribution, customer
habits (voice/data usage) Running specific traces on Network to
categorize problems Checking trouble ticket history for previous
problems Checking any fault reports to limit possible hardware
problems prior to test
Subjects to Investigate Nonworking sites/sectors o Inactive
Radio network features like frequency hopping Disabled GPRS
Overshooting sites coverage overlaps Coverage holes C/I, C/A
analysis Drop Calls Capacity Problems Other Interference Sources
Missing Neighbors Oneway neighbors PingPong Handovers Not happening
handovers Accessibility and Retain-ability of the Network Equipment
Performance
Faulty Installations
After the Test Post processing of data Plotting RX Level and
Quality Information for overall picture of the driven area Initial
Discussions on drive test with Local engineers Reporting urgent
problems for immediate action Analyzing Network feature performance
after new implementations Transferring comments on parameter
implementations after new changes
BENCHMARKING: Benchmarking service based on field data
collection and a comparative analysis process involving the quality
and coverage of different networks audited. This analysis is
followed by a full report and a set of recommendations that allow
the customer to identify their strengths and weaknesses compared to
its major competitors, always with the objective of improving the
network quality by applying the recommendations.
RF Planning:RF planning plays a critical role in the Cellular
design process. By doing a proper RF Planning by keeping the future
growth plan in mind we can reduce a lot of problems that we may
encounter in the future and also reduce substantially the cost of
optimization.On the other hand a poorly planned network not only
leads to many Network problems , it also increases the optimization
costs and still may not ensure the desired quality. Nominal
planning , RF Network Planning, Neighbor planning , Coverage
Planning & Frequency Planning, Preparation of Database (LAC,
CI,) , Creating daily KPI report based on Daily Counter. Taking
Status of Survey Site & Co-ordinate with Survey Engineer &
Survey Co-ordinator.
RF Planning Tools: Planet, Pegasus, Cell Cad Net plan by
Motorola, TEMS by Ericsson
Actix Atoll Planet Net dim by Nokia
Network Planning Tool:Planning tool is used to assist engineers
in designing and optimizing wireless networks by providing an
accurate and reliable prediction of coverage, doing frequency
planning automatically, creating neighbor lists etc.RF Network
Planning and Optimization Software and Tools ... like Actix, XCAP,
Atoll, Planet With a database that takes into account data such as
terrain, clutter, and antenna radiation patterns, as well as
graphical interface, the Planning tool gives RF engineers a
state-of-the-art tool to: Design wireless networks Plan network
expansions Optimize network performance
Traffic Modelling Tools: Traffic modelling tool is used by the
planning engineer for Network modelling and dimensioning. It helps
the planning engineer to calculate the number of network elements
needed to fulfil coverage, capacity and quality needs. Net dim by
Nokia is an example of a Traffic modelling tool.
Project Management Tools: Designing a cellular system -
particularly one that incorporates both Macro cellular and
Microcellular networks is a delicate balancing exercise. The goal
is to achieve optimum use of resources and maximum revenue
potential whilst maintaining a high level of system quality. Full
consideration must also be given to cost and spectrum allocation
limitations.
A properly planned system should allow capacity to be added
economically when traffic demand increases.
RF PLANNING PROCEDURE: Terrain, Clutter, Vector data acquisition
and setup: --Procure the terrain, clutter and vector data in the
required --Setup these data on the planning tool. --Test to see if
they are displayed properly and printed correctly on the plotter.
Setup site tracking database: --This is done using Project
management or site management databases. resolution.
Marketing Analysis and GOS (Grade of Services)
determination:
--Marketing analysis is mostly done by the customer. --Growth
plan is provided which lists the projected subscriber growth in
phases. --GOS is determined in agreement with the customer
(generally the GOS is taken as 2%)
--Based on the marketing analysis, GOS and number of carriers as
inputs, the network design is carried out. Zoning Analysis: -This
involves studying the height restrictions for antenna heights in
the design area The objective of a cellular system is to provide
quality communication to the maximum number of users in a defined
area. The number of users supported by the system can be increased
by using more frequencies. Frequency resources are however always
limited. Hence RF Planning engineers are required to maximise
spectrum efficiency.
Site Location Proper site location determines usefulness of its
cells. Site are expensive and have to be chosen carefully. The
planner needs to visit each and every site.
Good Site Selection We need to understand various factors we
must take into account to ensure that the selected site is good.
Simple way is to ask yourself three questions 1) Why am I putting
this site ? 2) Will this selected site serve that purpose ?
Module E: RF Data PreparationSteps for Making RF Report using
MAPINFO Tool: 1.Export the log files( For this u can see previous
pages) 2.After making export we will open our export in MapInfo.
3.For making report see in your MapInfo .At the top of your MapInfo
there is map or not? Of course it will be there then follow this:
Go to Map-Create thematic map-ok-here we will see templates( From
here we mostly use point rage default)-Next---Choose which you
want-Next--arrange of ranges(How we arrange:-Go to custom-ranges(We
can change as our
requirement)--Reclac-ok--style--Marlette--ok-------- To open
MapInfo Professional
Choose Start > Programs > MapInfo > MapInfo
Professional 6.5 or click on the shortcut on the desktop if one is
created. To analyze drive test data using MapInfo, you will need an
input data and this input data is the TEMS exported log files. If
you have not exported log files, check the previous pages on how to
export log files using TEMS Investigation. MapInfo can be used to
analyze RX_LEV and RX_QUAL as we shall see in the following To
create a Thematic Map simply following the steps below: Step 1: In
this step click on Open Table on the toolbar or menu bar and the
Open Table dialogue box comes up Open Table window
File name Select file name where saved Files of type Select
MapInfo (*.tab)
Preferred View Change from Automatic to Current Mapper. After
selection click Open The result (map path) will be displayed as
shown-
Creating Thematic Map To create Thematic Map, from menu bar
choose Map > Create Thematic Map. The Create Thematic Map - Step
1 of 3 dialog displays. Creating a thematic map is a three-step
process: Step 1: Choosing A Type Of Thematic Map Thematic templates
allow you to make a thematic map based on values and settings in
our default types, alter these settings and/or save them as a new
template you can use again. When you first create a thematic map,
you begin by selecting a template that you can modify to suit your
requirements. You cannot create a theme without using an existing
theme template.
To create a thematic map you can only use the Ranges under Type
(see fig.) Type: Select Ranges Template Name: Select Template Name
(e.g. Region Ranges, Solid Yellow-Blue,Dark
Click on Next
Step 2: Step 3: Customizing Your Thematic Map. The last step
allows you to customize your thematic map, or create the map based
on the default settings. You can also preview the map's legend
before you display the map, and change the legend's label order.
Select a Table and a Field. Table: Select a table (these tables are
log files) Field: Select a field (specify what you want to analyze
e.g.RXLEV_FULL) Click Next
Preview
Displays a sample legend of the thematic map you are creating
Legend label Order Ascending and Descending determines the order in
which range and value labels (for ranged and individual values
maps) and field labels (for all other thematic maps) appear in the
legend. If you are creating a ranged map, the order you specify is
also shown in the Customize Range Styles dialog. 1. Choose
Ascending to display ranges from lowest to highest value. 2. Choose
Descending to display ranges from highest to lowest value.
Customize: The buttons in the Customize group enable you to change
the default settings of particular aspects of your thematic map
Ranges - Allows you to customize settings on a ranged map. This
option is available for ranged and grid maps.
Method For Customize: Select Custom # of Ranges: Select 4 to
define the ranges for RXLEV_FULL or Select ranges for RXQUAL_FULL
Define the minimum (>=Min) and maximum (-75dBm) 20 35
(-90dBm=