- This topic has 4 replies, 1 voice, and was last updated 13 years, 4 months ago by Pix.
6th July 2007 at 08:38 #48077juvyGuest
can u pls help me what parameter to change. when the speed is more than 60 km/hr one cell doesn’t HO even the neighbor has good signal. the result is drop call. they are in the same layer. we are using huawei bts. tnx6th July 2007 at 09:57 #48078PixGuest
Ok, it is good you said they are in the same layer. Check also they are in the same BCCH band.
Check the cell is defined as a neighbour in the OMCR. Is this a cell that belongs to the same MSC ? same BSC ?
Check that the traffic in the neighbour cell is not too high (high load in neighbour cell will slow down the better cell HO, or even inhibit it)
Check that HO_MARGIN(serv, neigh) = 5dB and A_PBGT_HO(serv) < 14 (normally, it should be equal to 8 or 10) Check that you didn't do a HO before, so you're not experiencing a PING PONG hysteresis. Ok, i think that covers pretty much evereything... Check also the QoS stats (INCOMING HO REQUESTS and TCH TRAFFIC ERLANG) in the neighbour cell. Verify that incoming HO are possible, and especially the better cell HO. Check per adjacency that HO coming from your serving cell are successful. Good luck,8th July 2007 at 04:25 #48079juvyGuest
thanks pix! your inputs are greatly appreciated.. i will review the parameters. maybe you have more to add with this clearer scenario.
the scenario is that,in a 200 meter tunnel. the car is moving very fast and cell-1 serving. at the middle of the tunnel, there is low rx lev (-90 to 100 dBm) already, quality is 7. there should be HO to cell-3 because that is the best neighbor but the result is call drop. however when we move slow, HO is executed successfully.
can i use parameters in fast moving HO even if they are in the same layer?
thanks!8th July 2007 at 19:50 #48080pixGuest
oh ok… why didn’t you say that Ho were being performed at lower speeds ? according to your drive test, is it better cell HO or emergency ho ?
you can fasten up emergency ho :
ho margin(1,3) = 2
ho margin(3,1) = 2
a_pbgt_ho(1) = 3
a_pbgt_ho(3) = 3
ping_pong_margin(1) = 10dB
ping_pong_margin(3) = 10dB
timer_pingpong = 10s (for both cells, 1 and 3)
that might work better.
if you want even faster HO, try ho_margin = 0 or even -2 (but in this case, increase the ping pong margin to 12 or 14dB)
good luck with this 🙂9th July 2007 at 06:11 #48081PixGuest
understand “you can fasten up the better cell HO”, not the “emergency ho”. Mistyping, sorry 🙂