Coverage gap

[justdream]

Experts, I need your advice..
I've big coverage gap in rural area (as I don't have site in this area)
consequently high call drop number/ rate in this area

so I'm searching for temporary solutions to reduce the number of call drops as much as possible until they integrate the new site
what do you see :confused:

[Optim]

Ajust Rxlev access min on high value to avoid any MS connected with low signal...so in KPI statistic the CDR will decrease...but in filed!
same you can play on access by TA or distance...
Other action is to re design the azimuth and tilt,...
good luck

[danikd]

Experts, I need your advice..
I've big coverage gap in rural area (as I don't have site in this area)
consequently high call drop number/ rate in this area

so I'm searching for temporary solutions to reduce the number of call drops as much as possible until they integrate the new site
what do you see :confused:

What technology you are talking about? GSM? 900 or 1800?

The most efficient solution for GSM 900 is the following:

Antenna with high gain 18dBi (or even higher) this will require very precise installation (high gain antennae very sensitive for installation mistakes azimuth tilt)
Use two antennas with space separation of 3m at least (space diversity)
If your base station has more than 1 TRX, then use bypass connection for each TRX (i.e. with no combiner in TX branch)
For combination of 2TRXs sector, each TRX should be connected to each own antenna (2 antennas configuration)
Once 2 installed antennas are X-pol (+45/-45), then connect one TRX on first antenna to +45 port and second TRX on second antenna to -45 port
Activate Baseband hopping
In case if your RF cable length is greater than 30m it makes sense for TMA installation
Adjust emergency HO conditions parameters


Now conclusions:
1. For GSM 900 band the link balance between UL and DL occurs for TRX output 45dBm (thanks to MS Max TX power of 33dBm). Lower TRX power make DL weaker than UL
2. Space diversity is most efficient for open spaces rural environment where no so many signal reflections and refractions.
3. X-pol combination with space diversity gives additional benefits of polarization and space diversity together
4. Baseband hopping will give us opportunity to receive and transmit next frame in different conditions - we are using here polarization and space diversity for DL and UL simultaneously, which gives us additional benefits
5. TMA will allows us to improve BTS sensitivity and use high power TRXs (more than 45dBm output power)
6. TMA utilization will give us also good compensation for cable loss on UL.

By applying suggested configuration, you can achieve additional 5-9 dB for RF link improvement, which will lead to better performance

Enjoy

[justdream]

Ajust Rxlev access min on high value to avoid any MS connected with low signal...so in KPI statistic the CDR will decrease...but in filed!
same you can play on access by TA or distance...
Other action is to re design the azimuth and tilt,...
good luck

what do you think about Radio link failure? can it help?
I'm working in DCS/ E-GSM Network

[danikd]

what do you think about Radio link failure? can it help?
I'm working in DCS/ E-GSM Network

E-GSM it is GSM900 regular one, so what I mentioned in my message is fully applicable.

As for DCS (GSM1800), majority of items are fully applicable, the only thing that you should take into account is high power TRX and bypass mode for TX combining. This issue should be done step by step i.e. DCS (GSM1800) has limitation on MS Tx power (30dBm), this may lead to link unbalance. To use high power TX output with bypass requires TMA installation.

More notes: To solve coverage problem with DCS (GSM1800) seems for me pretty problematic. If you have GSM900 available, then this band should be use for such troubleshooting.

All mentioned TX/RX improvement techniques are well known and pretty well documented in every vendor's documentation. Their target to improve performance - Radio Link Failure is a problem that can be solved or reduced by using what I wrote before.

Before troubleshoot this problem for specific cell/cells, make root cause analysis to see, that the real problem is coverage i.e. low signal for DL and UL. While it can be interference, in this case start with cleaning up your frequencies first (most efficient way to get improvement)

[tremalnike]

Hi,
If you increase RadioLinkTimeout and RadioLinkTimeout_BS, you'll have minor improvement at statistic.
Just optimize ARFCN's to have maximum possible C/I in this area with low levels and think about implementing TMA to improve uplink.
Please tell us more info (combiner mode, number of TRX , hopping , antenna model) and plot RxLev and RxQual here to make situation more clear.

BR