CHEKING A CELL BY LOCKING FREQUENCY

In a drive test when we need to test a particular cell for overshooting we does that by FREQUENCY LOCKING. i.e. the frequency (ARFCN) of LUD877A was locked in TEMS and then drive test was done in dedicated mode.

Locking a frequency means that MS can not be latched to any other cell through HO and hence it tells us the signal level and distance from cell. So any changes to be done in the cell would show result.

BBH Report(Busy Bounce Hour Report) CHR269A- Only 1 TRX card with 5 TCH HO success=94.87%

Sd erl=19.20 Tch erl=22.1 SD Blocking=0.04 D1%=0.9%,D3%=1.8%

Total attempted calls=3010, established=1200 TCH assign=95.3% Loc Upd= 3564 CHR269B- RASR=93.53% HO=95.81% D1%=0.7% CHR269C- D3%=3% CHR617A- D3%=1.3%

Sd erl=31.74

D1%=1.8%,D3%=1.9% TTCONGS_H=10 CHR617C- Tch erl=21.9 D1%=1.8

Diff b/w total calls and established calls is very high Loc upd=198

CHR655A- HO=93.22%

D1%=1.1%, D3%=2% Diff is high

CHR655B- Has good performance CHR655C- D1%=2.6%,D3%=1.6% HO= 97.9%

TCH block=0.08

1) TRX cards can be added to increase TCH

2) HO rate can be less cause of unavailability of TCH, hardware fault, neighbor not defined, interference, lack of dominant server.

Hardware fault can be checked by checking feeder cables connection, TRX cards, Combiners, problem in neighbor cell. Neighbors could be defined via MCOM, interference can be reduced by checking the values of BSIC and BCCH, and also checking out HO margin could solve the purpose.

3) High Sd erl and Tch erl if accompanied with less TCH could cause congestion.

4) SD Block could occur due to congestion, alarms, sector swap, wrong LAC defined. TCH Block due to alarm or congestion.

5) D1 is SD drop and D3 is TCH drop which could occur wrongly defined LAC, SDCCH or TCH assignment failure, interference, same BSIC, lack of capacity, high signalling load, unsynchronized SDCCH, low coverage or sector swap.

6) Difference between Total calls and calls established is high due to reasons such as drop due to HO failure, Interference on target cell, Incorrect serving cell, low signal level and quality, long TA, MS enter on high attenuation area like tunnel or building, high cochannel and adjacent channel interference, extranious Interference, hardware issues.

HO can cause problem when HO not defined, BSIC, BCCH same, cable swap, TCH not available in neighbor cell, fading, Interference, HO margin not properly defined, LAC not properly defined, faulty hardware, E1 terminal swap, lack of dominant server, one way neighbor defined.

rx level, interference, hardware failure.

8) Loc Updation is high which cause signalling load.

9) RASR being less signifies missing of RACH channel which can be checked by Signal Trace Tool and then checking the reason problem can be solved.

10) TTCONGS_HR tells us that the particular site faces congestion only occasionally.

1) HO success rate should be more then 95%. But here in case of site MH519A it is 93.02% only and in MHA14B it is 92.41%. 2) D3% i.e. TCH drop is 2.3% in MHS49B, 1.3 in MH519A, 2.2% in MH519C and 2.0% in MOHA14A.

3) D1% i.e. SDCCH drop is 0.9 in MH519A.

4) TCH erl is more in MHA14B as compared to TCH available which could lead to congestion. 5) TTCONGS_HR is 16 in MH519A which tells us that here congestion occurs sometimes occasionally. 6) SD Blocking is 1.9% in MHA14A.

7) TCH assignment in MHS49B is just 89.1% which needs to checked. 8) Loc Upd is high in MHA14C which gives signaling load.

9) Diff b/w total calls and calls established in MHS49B and MHA14B is high which has to reduced by checking out the reasons.

BENCHMARKING DOCOMO BSNL VODAFONE AIRTEL

1) Which donot have any sharing i.e. only Site 2) Height of tower on the building top is 15 MTR

3) Height of building=G+3N=4+3(2)=4+6=10MTR (G=ground floor, N= no. of floors) 4) Lat Long through GPS(Global Positioning System) was different then planned. 5) Microwave antennas on site=1

6) Sectors=2 7) Azimuth=110,340

8) Antenna height=20,21(actual), 20,20.5(optimized) 9) Tilt E=0,4(actual), 0,7(optimized)

10) Tilt M=1,1(planned), 1,2(actual), 1,1(optimized) 11) BCCH=35

12) BSIC=25

In case of load balancing we balance the load of a site by increasing its tilt that is decreasing the coverage.

We do this for high loaded sites.The tilts of sites LU65B, LU186A, LU205C, LU240C, LU262A has been increased.The tilts of neighboring or adjacent sites LH71A, LU237C, LU549A, LU529B, LU537B has been decreased so that these sites can share the load.

The tilt of site LU211C was not changed due to weather problem

MICROWAVE ANTENNA SURVEY

AIM: The basic aim of Microwave Survey is to clear the Line of Sight (LOS)

LOS survey

Los survey consists of 2 steps: Map survey

Field survey MAP SURVEY

A preliminary study of the map is required for planning of one or more routes which might appear to be possible between the terminal points given.

FIELD SURVEY

Step1:Take the Lat – Long of the near end of the site from we will start our survey. Step2:Ask for the nearest link from we can clear the link easily which will be our far end.

Step3:After getting the nearest linkage site take the position with the help of map info and store the value in your GPS

Step4: Calculate the distance and bearing angle from the GPS with the help of GO TO option of GPS and start reaching towards the far end. Step5:While reaching towards the far end we will keep our eye on two things first the bearing angle and secondly Xtk.

Step6: During the whole journey from near to far end we will try to keep the value of bearing angle as much close to reference bearing angle. Step7:we will take the value of max height of building till the value of Xtk is 300m Step8:The place where the value of bearing angle will became equal to the value of reference bearing angle that point would be our LOS point. Step9:At the point where we will trace our LOS the value of Xtk will be zero.

RL TOOL TO For Microwave Planning

O P E R A T I O N S A N D M A I N T A I N E N C E C E N T R E R A D I O ( O M C – R DEFINITION

The OMC (operation and maintenance center) is a UNIX based centralized system, which supports the day-to-day operation and maintenance of Network Elements (NEs) within a GSM network.

NEED FOR THE OMC

The different network elements like the BSC, BTS, RXCDR etc. and their smaller hardware elements like the ports, DRIs, GPROCs, etc. are prone to failures and malfunctions. If these errors go undetected or unattended, then the equipment will definitely be damaged. Not only this, it may also prove to be service affecting i.e. it may cause the calls in some regions to go down adversely.Such a loss is unbearable by any operator. Hence to avoid such circumstances and to check and correct the faults at the network element ends, the OMC functions round the clock. Hence, at all times an Operations and Maintenance Center engineers monitors the network.

When an operator extends its network in order to establish coverage over large areas, the network can quickly grow to contain tenths or even hundreds of thousands of entities. An operation and maintenance system ties the management of all those entities together into one or several centers. Through such systems the operator can configure switches, add new base stations, and perform software maintenance, add subscribers and performs many other tasks.

At present, equipment manufacturers have their own OMCs, which are not compatible in every aspect with those of other manufacturers. This is particularly the case between Radio Base Station equipment suppliers, where in some cases the OMC is a separate item and Digital Switching equipment suppliers, where the OMC is an integral, but functionally separate, part of the hardware.

Whenever a new BSC or BTS is to be created it is firstly reported to the Operations and maintenance department to create the new parameters of particular in the database and to configure them. These parameters may be assigning of the frequency to the cells, adding new cells in its neighbor for effective handovers etc.

All the software, which is necessitating in the different GSM components like transcoder, BSC is done through this center. After the installation of the site the operator can login at any of the BSCs and afterwards to any of the sites to change and check the status that may include locking up of the DRIs, cell broadcasting of messages, checking for the calls, drop inserting one site with another so as to give redundant path, checking up for interference etc.

Operation & Maintenance Center

The Scaleable OMC system configuration is shown in figure. Each processor is a complete UNIX system, comprising the following:  A System Processor.

 Several MMI processors (which also provide color operator workstations).  A GUI Server that is configured as an MMI.

 A laser printer.

The Motorola OMC-R communicates with the GSM network using the X.25

Communications protocol to exchange Operation and Maintenance (O&M) data with the BSSs and speech Transcoders (RXCDRs or XCDRs) via a Private or Public Switched Packet Data Network (PSPDN). The Transcoder (XCDR) is the digital signal processing equipment required to perform GSM–defined speech encoding and decoding. In terms of data transmission, the transcoder interfaces the 64 kbit/s PCM in the land network to the 13 kbit/s vocoder format used on the Air Interface. The Remote Trancoder (RXCDR) is used when the transcoding is performed at a site away from the BSC, which is at or near the MSC. This enables 4:1 multiplexing in which the transcoded data for four logical channels is combined onto one 64 kbit/s link, thus reducing the number of links required for interconnection to the BSCs.

OMCR OPERATIONS & FUNCTION

An OMC works round the clock monitoring the network elements and network operation. A set of functions specific only to the OMC make it a ‗must have‘ department in the GSM architecture. A set of powerful tools provided to the OMC engineer by the state of the art software allows him to perform his duties in excellent manner and approach. The following tree shows the functions of the OMC department.

ICM (INTEGRATED CONFIGURATION MANAGEMENT) 1) ALARMS

2) CHANNELS ALLOCATION