- This topic has 26 replies, 1 voice, and was last updated 10 years, 8 months ago by Mania.
14th July 2010 at 07:50 #62158DeepakGuest
I just want to know what would happen if we have imlemented MaxTA restriction on some cell and now if we are checking some area served by this cell.The radio coverage is there now if the subscriber is out of range of TA restriction he would’nt be able to make call from that cell but does the MS will show radio coverage or signal coming from that cell14th July 2010 at 08:59 #62159BijoyGuest
The MS will show coverage as it can reselect this cell if it is the best server.But,its RACH will get rejected as BTS will calculate its TA & compare with MAXTA for that cell,if TA>MAXTA,he will not be able to establish a call.
Bijoy16th July 2010 at 06:53 #62160DeepakGuest
Thanks for the reply pretty much convinced but there is one query that the BTS sends intial TA value to the MS in SCH.Now then there can be any problem due to MAXTA restriction while establishing Radio link with the BTS or its just that it sends the TA value to the MS and dosen’t matches it with the restriction and does same only when RACH request is encountered from the MS16th July 2010 at 07:07 #62161DeepakGuest
My next query is regarding Coverage in Rural areas.Actually i want to know that how successful is the implementation of 1. High gain antennas with 21 db gain,i mean if we are having incar coverage in a villg say 4.5-5 km dist. and with Rx lev around -85 to -90 with uniform AMSL.with 18 db antenna then is there any possiblity that with implementing HGA we can provide indoor cov there i mean level will inc definitely but how much any propotions.2.TMA same case how much uplink will be affected 3. Implementing Uncombined mode if we are using Hybrid Combiners then with implementing Uncombind mode 3db loss will be cut off and covg will inc but how much.
I really need to address these issues as we are having constant Cust Complaints mainly due to indoor covg and implementing a new site is not possible since Our S&M team will not approve that due to revenue issues so i want to know how can we provide affective covg with less expenditure.
I personally beleive People having vast field experiences can address it with some practical soln anyways all suggestions are welcome and i shud stop writin bcoz its getin very big19th July 2010 at 06:00 #62162ManiaGuest
@ Regarding PMRES files.Its true they are found decoded in the OMCR in Compressed as well as non compressed format and their duration can be controled by OMCR. However the RMS data (CEll / TRX Level Quality Level, Pathbalance are )counters are stored in binary format. for the description of the counters like MC01 etc they can be found in RNO or there is a file which I am not sure Alcatel can share with you or not that is the “PM Counter Description”, also there is an access database that contains all such descriptions. Try the Alcatel guys and backdoors.
@TA Max. Well the cell site evaluates the TA from the RACH. if it exceeds the TA limit then
its automatically discarded. now the MS would not know that the RACH has been discarded so it woulod assume a RACH collision and after the SD_assignment guard timer would resend a RACH on the same cell that too would be rejected. now it would try this for Max_Retrans times and then reselect to any other qualifying cell for a time I think 10 sec (have to check) before reselecting again to the best server. this time is enough for another attempt so a RACH is sent on this cell and hopefully it would get a TCH. if you havent played aroung with dedicated mode coverage then in normal settings the call would soon handover to the cell with max_TA limit. so you might have to cater for that too.
@High power antenna.
Well in terms of coverage enhancement it does work.
you can also look for other options like having TRXs in coverage mode, on in air combining.
only drawback of high Gain antennas is that the ones we have only had one port so there was no diversity. also since we only wanted coverage to we did not add any combiner and so had only one TRX per antenna. you could try power based concentric cells for catering for capacity.
In LNA in Uplink the received power does increase but try and find LNAs that have alarms reported when they develop faults as else debugging the LNA equipped sites would be next to impossible as they do get faulty for no reason.19th July 2010 at 08:20 #62163pixGuest
the simplest solution is to bypass the combiner : you gain 3dB in downlink.
but then, your uplink will be limited. Therefore, a LNA (or TMA, that’s the same) should be implemented. I don’t know about LNA faults, as Mania suggested. Get a well-known brand I guess.
But in the en, it’s a lot of trouble to gain only 3dB !
All considered, and as Mania said, use the Twin TRX in coverage mode (that’s an Alcatel solution, but i think other vendors also propose something like this, don’t they ? one twin TRX connected to 2 cross-polar antennas : 2 Tx-div + 4 Rx-div, and a huge Tx power…) Here, no need to use HGA : the power is so high, with diversity on top of that… that’s plenty enough. Expect 10dB increase !
Another solution would be to use an indoor repeater, with a donor antenna outside. That might be too expensive though ?
pix19th July 2010 at 10:31 #62164DeepakGuest
Hi and Thanx everyone
Well Our vendor is E// and we have Our TRx in the same scenario as mentioned it is called DRU consisting of 2 TRx with 2 and4 diversity for Tx and RX respectively.Well yes Uncombined should be there but when site expansion is done sometimes we have to combine 4 tRx with same antenna using Combined mode due to antenna loading isssues(Owner issues. anyways looking for inc antenna ht and opening tilts wherever it is possible but then Drops can form an issue.anyways thru my observation i have noticed that HGA if implemented with in 3-3.5 Km can inc the indoor covg.And Outdoor repeater can be an option if Our S&M team approves can provide coverage up to .75-1 km range19th July 2010 at 14:20 #62165pixGuest
when moving from 18dBi to 21dBi, the gain in the end is only 3dB in front of the antenna.
On the sides of the antenna, there will be a coverage decrease.
Also, ensure that your downtilt & azimuth are facing the indoor you want to cover. Try different settings, you might get some interesting reflections that could help covering the indoor area.
pix20th July 2010 at 05:17 #62166ManiaGuest
Think you should also consider installing a repeater. that way you can increase the coverage area of your cell easily without sacrificing the capacity. as the village you are trying to cover is not far off and it should be possible to cover it.. or you can use seperate antennas instread of using combiners. this way you don’t loose 3dB but you may get coverage area mismatches if Azimuth / tilts of antenna are not perfectly matched, this can result in degradation in KPIs20th July 2010 at 19:51 #62167Fresh OptGuest
using separate antenna instead of using combiners, did you mean antennas should be connected directly to transceivers? Anyway it has to adapt TRX cable with antenna cable, so, we need connectors and hence atenuation, maybe less than 3 dB. Is it worth having such a solution? Please elaborate more regarding this, it looks a good solution in rural areas with bad coverage.
Fresh Opt21st July 2010 at 06:31 #62168pixGuest
instead of combiners, you just need duplexers & splitters. In ALU it is called the ANB (previously ANX, i believe)
But as I said earlier, you increase the DL signal by +3dB alright, but the UL signal is not increased. You probably need to add a LNA when using this solution.
pix23rd July 2010 at 12:26 #62169ManiaGuest
yup pix is right ANX with LNA. Also if you have RACH_FAilures pegged by cause value you can check if the coverage is limited due to UL as it has RACH_Fail due to UL. If that is the case then LNA alone might also do the trick