- This topic has 17 replies, 1 voice, and was last updated 7 years ago by sunil.
2nd August 2008 at 12:01 #53356RGuest
why there are only 8 time slots on a TRX ?
why not greater than 8 or less than 8 ?5th August 2008 at 03:53 #53357MKTGuest
Its a trade off between capacity and quality.
They tested 16 32 4 and 8
8 is a balance of all benefits.
If you have 16 TS on a TRX
you will have similar experience as that of HR(half rate).
And please note it has to be in power of 2, ie binary.
MKT8th August 2008 at 14:17 #53358RGuest
can i find it somewhere specifically in docs, something u can suggest !
rgrds8th August 2008 at 14:21 #53359RGuest
why in power of 2 only ?9th August 2008 at 03:40 #53360MKTGuest
Every thing is digital now
and digital uses binary system.13th August 2008 at 07:48 #53361RGuest
In voice we do the planning like :
for a given GOS and the traffic in erlang , we can plan a site/sites with say (n) no. of trx ( traffic channels )
Is there something like that in case of DATA ( GPRS/EDGE ) planning ??
i.e , for a given throughput DL how can we plan the no. of radio timeslots to be given at a particular cell/site ….21st August 2008 at 07:46 #53362RGuest
need ur expert comment for the question below !22nd August 2008 at 10:58 #53363BloodyGuest
This planning of Data calls is already done when you are going to plan for TRX. Because ultimately TRX are responsible for Data calls as well.
But the first priority is given Traffic channel and then to data channel.That’s why you well get less surfing speed while in peak hours and more at the time of night.
There is no GOS for data calls.23rd August 2008 at 21:05 #53364pixGuest
the design of a site (number of TRX, number of sectors) based on voice traffic + data traffic is the right way to go.
Unfortunately it is not easy to predict how much and when the GPRS is going to be used. It’s also difficult to estimate the amount of throughput required by the users in order for them to feel it’s “good”.
For instance, for web surf, you don’t need so much throughput. But what you need is fast response time…
an easy way is to always ensure the voice TCH are not using up all the timeslots (at least 2 or 3 are always available per cell, in order to provide “satisfying” GPRS access)
QoS indicators can help you with that. Then you can perform drivetests in order to check out the overall data service “quality” of your operator. Do you “feel” that’s good enough ? Don’t forget, we’re talking about a very subjective matter here. You need to isolate some key performance results in order to qualify your network. Ping response time, throughput, reselection time, retransmissions, etc…26th August 2008 at 08:23 #53365RGuest
ya , u r very correct that , it is a very subjective discussion.
The QOS indicators are the RTT , Retransmissions , throughput/TBF .
Pix, my RTT value is around 280ms for EDGE and 450 ms for GPRS( pinging at firewall ).
average throughput/TBF DL/UL as 120kbps/25kbps EDGE
average throughput/TBF DL/UL as 36kbps/6.1kbps GPRS
i want to increase it further but how ??
can u suggest me what can i do furhter at radio level?26th August 2008 at 12:22 #53366SHRAWANGuest
TRX TS is basically depend upon TRX Signaling and which based on E1 so i we set 16 TS then one more E1 require26th August 2008 at 17:07 #53367pixGuest
you can check interferences and coverage. That’s all you can do at radio level.
Most probably, you need to increase your radio and abis capacities.
Perform drive tests to see why your EDGE throughput is so low…
regarding the RTT, that seems like a good value.. what RTT of subsequent pings ? (meaning, pings coming AFTER the first ping : the first ping takes a while usually.. the next pings are faster because they reuse the same TBF)12th June 2011 at 01:14 #53368AbhiGuest
why a TRX has only 8 time slot ?13th June 2011 at 11:34 #53369OptimGuest
Good Re-question on the same thread.
I’m sure PIX is working on it and will answer you in a while 🙂
rgrds,13th June 2011 at 19:02 #53370pixGuest
optim -> :)) i wasn’t going to…. but since you ask…
time is infinite, and when someone was asked to slice it into little slots.
who asked ? probably a manager of some sort.
anyway, this guy first decided to cut it into 0 slots. Dividing infinity by 0 was quite an impressive task, but yet it didn’t quite blow away its manager. Indeed, it didn’t comply with the requirements : it was nearly impossible (within the assigned budget) to apply half-rate to such slots.
So he divided infinity by infinity itself, which is symbolized by the number “8”. By the end of the day GSM was born.
But from the first experiment, a lonely timeless burst went rogue. It quickly evolved into CDMA, a parallel universe where timeslots are banned.
I guess I should update wikipedia with this story.