CDMA Radio Network Optimization Plot Analysis (using Actix)

Salam…
In this Post I wanna answer a question from a friend of mine who has commented here. Hope this post will useful for us. Sorry if I post a little bit late, because I have a little work in Ketapang :)

Lets begin.
First I wanna share a little bit about Optimization Process. Optimization process consists of 3 main steps ,i.e.:

    1. Preparation (Tools: hardware and software setting, scenario setting)
    2. Data Collecting
    3. Post Processing and Analysis

Actix is a well known post processing software which is powerful enough to help Optim Engineer analyze the network problem and create the Optimization recommendation. In this post, I just wanna share about Plot analysis (requested by Vikaz via comment and email).

On Actix, there are 3 main standard procedures in Optimization analysis, i.e.:

    1. Site Verification (single cell Optimization)
    2. Cluster Verification (a group of Cell Optimization: 10 Cell more or less)
    3. Network Verification (combination of 2 previous stages to verify whole network)

Let’s go to Plot Analysis.

Actually on CDMA, there are 4 Performance Indicator that we have to analyze:

    1. Forward FER
    2. Rx Level (Mobile Received Power)
    3. Ec/Io
    4. Handset Transmit Power (TxPO)

you can read those definition here :)

Below are vikaz actix plot, that I’ve received from him via email. I assume these Plots below, is an example for site verification because the drive test route mostly on the Sec-3 Ballabh garh site coverage area. CMIIW :)

Plot Analysis (Site Verification)

Forward FER Plot

From visual check, at least there are eight spots with bad FFER. On those spots, voice communication quality isn’t good enough. So we have to find out why it can be occurred on those spots with following plot analysis below.

Rx Level Plot

From Rx Plot above, we can conclude: there are no Rx Level Problem a long the drive test area. We can go to the next plot.

Ec/Io Plot

From visual check, we can conclude that there’s a spot which has bad Ec/Io. We have to check Mobile Transmit Plot for deeper analysis.

TxPO Plot

Above picture display Mobile Transmit Power along the drive test area. We can see that TxPO is good enough to provide good quality communication.

So… What’s going on with the BAD FFER’s?

Well before we goo deeply in to next steps, I think it’ll be helpful if we discuss about CDMA Signature Table.

CDMA Signature Table

According to CDMA performance Indicator (you can read on my previous post here), below I’ve made a little table which is useful to guide us to the next step Analysis.

1. Normal Signature ( my own value, just find another source to compare the value ^_^)

  • Normal FFER : 0 to 5 (in percentage)
  • Normal Receive Power (Rx Lev): -30 to -100 (in dBm)
  • Normal Transmit Gain Adjust (TxGA): depends on site configuration, loading and NOM_PWR Setting
  • Normal Ec/Io: more than -12 dB
  • Normal Transmit Power: less than 20dBm
  • Normal system parameter messages on forward and reverse

2. Abnormal Signature, consists of several condition i.e., as you see in this table below:

According to the Plot Analysis and Signature Table above, we may conclude that vikaz’s network suffer “Forward Link Interference” although the Ec/Io wasn’t too bad (according to the plot). But we can go deeply to Ec/Io plot analysis.

Ec/Io Plot Deep Analysis

Plot analysis below just an example of deeper Ec/Io Plot analysis. Without mind to give incorrect article, but because of one and another reason I just can provide you these plot to give some illustration about Ec/Io Analysis deeply:

1. Ec/Io PN Combined (different log file)

well.. let’s zoom it, so we can see Pilot Pollution area more detail.

Above picture shows us the desired PN on site ID 239 are: PN105, PN273, and PN441.All of these PN’s are potentially interfered by it’s neighbor(s), i.e. :

  • PN105 is potentially interfered by PN201 and PN051 (in case there are somethig wrong in BTS logical and physical configuration)
  • PN273 is potentially interfered by PN30.
  • PN441 is potentially interfered by PN123.

let’s find out which PN’s caused Pilot Polution. Below are Ec/Io per PN analysis.

2. Ec/Io PN105

3. Ec/Io PN201

From the picture above, we can see that PN201overshoot to PN105 coverage area and cause coverage hole on it. We may purpose some recommendation to repair the physical and logical parameter at PN201sector including Tx_Power, and Antenna Tilting and orientation (vertical and horizontal).

4. Ec/Io PN273

5. Ec/Io PN30

And then.. let’s analyse another site239‘s sector.

6. Ec/Io PN441

PN123 analysis which has potential to interfere PN441 is skipped, because I don’t have enough data to do that. I’m sorry… at least, from this post we can conclude that Overshooting Sector with certain PN, could cause forward link interference. Forward Link interference trigger bad FFER on the network.

Pilot Polution is a case which is on a certain sector, there are too much PN active, and lack of dominance. This could happen when there are too many sectors overshooted. Pilot Polution could cause drop call, block call, bad FFER. This is the worst scenario problem in CDMA air interface caused by bad Planning, (or) Installation and (or) commissioning.

The Recommendation to fix this Forward Link Interference problem is:

  • Check the BSS Parameter of the site. If there’s anything wrong such as BTS Tx_Power, Neighbor List, and Closed Loop Power Control Parameter.
  • Check the Antenna Orientation and Tilting of each site and repair it.
  • In case there’s a repeater on the coverage, check the Tx and Rx gain on Uplink path.

Maybe enough for this Post, and I hope it will useful for us who want to learn how to Optimize CDMA air Interface. I believe this article is far away from enough, so if there any mistakes.. please correct it together. Thanks. ^_^

ps for Vikaz : thanks for giving me such a nice material, and share it to us. Is there any questions please let me know. Sorry I’m late :)

salam…

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You’re currently reading “ CDMA Radio Network Optimization Plot Analysis (using Actix) ,” an entry on pram

Published:
1.14.09 / 12pm
Category:
2G, CDMA2000, Network Optimization, Telecommunication