PROJECT RESULTS

9.2.1Actions Taken on Project

 Replacement of Faulty Hardware

 Infra Audit done for suspected problematic sites

 Neighbor Optimization done for all cells

 Radio Parameters tuned for cells having BAD KPIs

 Traffic Optimized by equipping Half Rate and Reconfiguration

 Drive-Test performed for analysis of network problems & verification of solutions

 Continuous tracking of KPIs, Availability & Alarms in order to drive & track the project progress

10.2.3 TARGET TO BE ACHIEVED FOR BASIC KPIs

 Handover Success Rate (>95%)

 SD Assignment Rate (>95%)

 SDCCH Drop Rate (<1%)

 TCH Assignment Rate (>97%)

 TCH Drop Rate (<2%)

10.4 Improvement in Handover Success Rate (HOSR)

Case: the bad value of the HSR is 67.86 which we have to improve it to increase the performance of the network

Reasons:

i) Problem in the site hardware.

ii) Neighbors are not define in bi-directional. iii) Serving cell congestion.

iv) Coverage issues

v) Co channel interference & adjacent cell interference.

Solutions:

i) Drive test to the site find out the faulty hardware and replace it.

ii) We define the neighbor in bidirectional which increases the performance of the site and leads to achieve the targeted value that is 98%

Fig:10.4 Case: The SDCCH drop rate should not be greater than 1%

But in the above we analysis that the drop rate is more than 1%the site name 11SDS the SD drop is 5.44% which is very bad performance to overcome this problem check all the parameters of the site find reasons for the bad SD drop rate.

Reasons : i) co channel interference and adjacent channel interference.

10.6 TCH blocking rate

Fig:10.6

In the above BBH (business bounce hour report) show that the performance of the TCH blocking KPI (which is define as the proportion of TCH requests from origination and hand in calls that is fail due to there being insufficient TCH resources to carry the call) is good but only bad value is one that is 6.7

Reasons :

i) Problem in the hardware of the site. ii) Coverage issues

Solution:

10.7 Improvement in TCH Assignment Rate

Fig:10.7

Case: in the above BBH report the TCH assignment rate is vary from 100 to 91.52.the 100 value the good value but the 91.52 is the bad value for the network and this leads to decreases the performance of the network. This value of the TCH success rate decreases the CSSR (call setup success rate).

Reasons for the bad value of the TCH assignment success rate:

i) Problem in the site hardware.

ii) Subscriber no. is more as compare to the TCH configure in the site. iii) Coverage issues

iii) Check the related parameters and know about the reasons .

10.8 Improvement in TCH Drop Rate

Fig:10.9 TCH should not be greater than 2%

Case: But in the above report in many cases the TCH drop rate is very high up to 13.33%.the another bad values are 8.62, 6.92, 4.76 all which is greater than 2 % that is mark as a bad KPI in the network.

Effect on the network: decrease the network performance that due to this reason the call success rate is decrease the value which is above the 2% is the bad value for the network and need to improve these value by using different method.

Reasons for the bad KPI values:

i) Problem in the hardware of the site that is TRX card, feeder cables, may be in the time slot.

ii) The no. of TCH configure is less as compare to the capacity of the site.

i) check the hardware properly i.e sector wise TRX if there is only high rate of TCH drop in one TRX card then problem in the TRX card

only solve the problem. Solutions:

I) Check the TCH full rate and half rate channel and the Bust hours of the network if the TCH drop is only high during the busy

hours then need to add the capacity to the site.

Fig:12 Case 1: Add the capacity in the BTS i.e add the TRX card

Reasons to add the TRX card: Utilization of the site is more as compare to capacity. This cause to decrease the performance of the network.

Solution: To solve this problem add the TRX using the Erlang table in the 2nd _{sector of the BTS. Because there is only one TRX is available in the BTS}

CDMA Optinization

Drive Test Application in Call Drop Analyzing

Call drop is the interruption of call and it is caused by BTS or MS releasing traffic channel without user permission. Call drop mechanism

CDMA system is a closed-loop system, the closed-loop signal link is very necessary between BTS and MS in data or voice transmission. Some important process, like power control and handoff, all need one closed-loop link. If this link is broken for any reason, MS will lose control and need initialization again and go back to idle state. When closed-loop signal link is broken, call drop mechanism will be started. Closed-loop signal link includes forward link and reverse link, any one link is broken can cause call drop.

1 MS drop mechanism

1. MS bad frame

If the mobile station receives N2m consecutive bad frames on the Forward Traffic Channel, it shall disable its transmitter. Thereafter, if the mobile station receives N3m consecutive good frames, the mobile station should re-enable its transmitter.

(Extracted from 95 standard 6.4.4) In 95 standards, N2m is defined as constant 12; N3m is defined as constant 2.

2. MS fading timer

The mobile station shall establish a Forward Traffic Channel fade timer. The timer shall be enabled when the mobile station first enables its transmitter when in the Traffic Channel Initialization Sub state of the Mobile Station Control on the Traffic Channel State. The fade timer shall be reset for T5m seconds whenever N3m consecutive good frames are received on the Forward Traffic Channel. If the timer expires, the mobile station shall disable its transmitter and declare a loss of the Forward Traffic Channel. (Extracted from 95 standard 6.4.4) In 95 standards, N3m is defined as constant 2; T5m is defined as constant 5s.

3. MS acknowledgment failure

If the mobile station has not received an acknowledgement within T1m seconds after transmitting the message, the mobile station shall retransmit the message. (Extracted from 95 standard 6.6.4.1.3.1.1) The mobile has N1m attempts to transmit a message that required acknowledgment. If the mobile does not receive the acknowledgement T1m seconds after the N1m time, the mobile declares an acknowledgment failure. In 95 standards, N1m is defined as constant 3; T1m is defined as constant 0.4s.

2 BTS call drop mechanism

1. BTS bad frame

when FER reaches to 90% in 100 frames and this happens 3 times consecutively, BTS will release the links. 2. BTS acknowledgement

There 9 times for BTS acknowledgement, and the waiting time between two acknowledgements is 0.4s. Integrated analyzing

Call drop ratio can be used to evaluate network integrated performance. Call drop ratio improvement can decrease subscribers‘ complaints and increase their satisfaction. For the large scale commercial network, call drop ratio observed from background OMC is more accurate and impersonal; for unloaded or light-load network, it can be got by DT test. In DT test, the call mode adopts ―sequence call test‖, call drop ratio is defined as: call drop number/total successful call number; if adopts ―long call test‖, total successful call number is total calling time (s)/90. For urban area, call drop ratio is less than 0.8% means network performance is good; for suburb or roads coverage, this index can be a litter low.

CDMA Drive Test Plot .

CASE STUDY

As we can see the orange color, this shows that rx level is decreasing hence signal level and quality is poor. The main reason which can be guessed by looking at the drive test is the distance between the two BTS. PROBLEMS FOUND ON OPTIMIZATION

1) TILT given is 8 degrees 2) HO Margin defined 20dB AFTER OPTIMIZATION 1) TILT to be reduced HO Margin to be changed CASE-2

1) HO defined was one way that is L639 cell‘s 1st _{sector is serving and not}

the cell L603.

AFTER OPTIMIZATION

1) Neighbors should be defined in both ways

Case -3

CASE-6

Initially the rx level shown is poor.

While optimizing the case given a Site was proposed

This site need to be defined as the neighbor of the previous one so that Handovers can occur and the signal level may improve at the areas. The frequency range of site implied can be checked after the site installation by frequency locking method.

PRN011 is the serving cell in this case.

But as we move away from the cell rx level decreases.

which has to serve in real.

i.e. sector 2 of cell PRN011 has to serve but sector 3 is serving. This is known as sector swap.

And hence cable trace has been proposed.

In case of cable trace the reager is asked to trace cable starting right from the GSM antenna to the BTS.

In this case the ideal mode drive test has been done.

The problem is that the cells are far apart so the signal level is decreasing while going away from cell PRNI01 and then improves near SPU001. The another reason which could have been possible is the given tilt to the sites which decreases the range of the sites.

In this case the dedicated mode drive test is being done and here as we see the rx level is improving as we move towards SPU001 from taseemo. Rx level at taseemo was very less.

Therefore there is a signal problem at this place. This needs a site installation but as nearby areas donot have such problem the repeater could solve the purpose.

It was proposed installation of repeater and therefore the complaint have been solved successfully. Moreover if SPU001 has any tilt, reducing that tilt would increase the coverage.

And also this IBS should be defined neighbor with SPU001 for HO.

14.2.5

Here there was complaint by Firozpura customers about the signal.

14.3 CHEKING A CELL BY LOCKING