- This topic has 12 replies, 1 voice, and was last updated 13 years ago by Usman.
10th April 2008 at 07:21 #51833taqiGuest
can any one tell me the worst UL and DL power in Dbm.(when we calculate interference in Air interference)12th April 2008 at 06:58 #51834pixGuest
interference is measured in dB, a level is measured in dBm… a bad level is -110dBm, an interference cochannel is considered at c/i < 9dB17th April 2008 at 13:50 #51835SHARKIEGuest
Thank you for your response to my previous question.
However, i have a case were am having a high SD drop on a number of sites. this i have observed for a few days now. i did define some missing neighbors on a few sites, what could be the reason for this high SD drop?17th April 2008 at 14:05 #51836pixGuest
hardware problems (TRX, BSC boards, path loss unbalance)24th April 2008 at 03:09 #51837ZHTGuest
Does anyone know how would the MS select which uplink frequency to communicate with the BS?
If there are “alot” of MS making a call simultanuously at one BS, would there be a very bad uplink interference?24th April 2008 at 06:25 #51838pixGuest
each mobile is assigned a particular frequency during the call setup. up to 8 MS can share one frequency in uplink.
Each MS is also a particular timeslot on this frequency : a frequency is divided in 8 slots, one slot is a certain schedule of usage. So each MS will transmit UL signal at a certain time, at a certain frequency. This is GSM 🙂25th April 2008 at 09:27 #51839ZHTGuest
Thanks Pix for your prompt reply. Can the BS select which UL freq to assign to the MS? If there is a band pass filter installed in the system, would it be possible to programme the BS to select which UL freq to assign?25th April 2008 at 14:37 #51840pixGuest
GSM is based on FDMA : the frequency band is divided into channels of 200kHz each, with channels in downlink and channels in uplink.
A pair of channels UL+DL is represented by a number “ARFCN”. In GSM900 there are 124 channels, from ARFCN=1 to ARFCN=124.
ARFCN=1 correponds to UL=890.2 MHz and DL=935.2 MHz.
When a MS setups a call, it is allocated on one timeslot of one ARFCN (in case of NO HOPPING). The allocation is usually decided by the BSC, which chooses which ARFCN and which timeslot.29th April 2008 at 02:25 #51841ZHTGuest
How does the BSC select the UL frequency and timeslot for the MS to us?29th April 2008 at 06:21 #51842pixGuest
“for the ms to us” ??
i’m not sure i understand…
the BSC provides a timeslot to the MS, based on different criteria, such as voice/packet, hopping/not hopping, preference/no preference, dualrate/fullrate, etc etc
you got to find the document that talks about that in your vendor…3rd May 2008 at 19:45 #51843navinGuest
hi all. can any body hep me solve my network problem
during conversation speech getting disturb and again gets normal within the same cell. (no handover case.)3rd May 2008 at 21:15 #51844pixGuest
you should look for anything that could generate interference in the area (alarm system, anti theft mechanism, army radar, DECT office phones, etc..)12th May 2008 at 06:42 #51845UsmanGuest
regarding the query that your voice/speech gets bad and that it again becomes normal you have to check few things:
1. you should check the BER/RxQual and FER value.
2. you should the C/I value because the voice quality usually gets worse due to interference.
3. you need to check that if the hopping is enabled or not because then you need to check the MAIO and HSN to identify the faulty DRI
these all reasons usually contribute to bad speech quality. even sometimes your mobile gets faulty and it is actually disrupting the voice quality.
thnx and i hope you may find the good reason of bad quality.