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Dear Pix
Ghost RACH requst can lead to sdcch drop or not?and when HLR check the channel request is fake or not?In my point of view
Ghost Rach Lead to SD blocking.
Can anyone update on whether there is any standard/specification which tells how many GHOST RACH in how much time are acceptable in any bts system??
hi,
3GPP TS45.005 p.42:
For a BTS on a RACH or PRACH with a random RF input, the overall reception performance shall be such that less than 0,02 % of frames are assessed to be error free.So random noise should be decoded as a noise for 99.98% of the time
0.02% of the noise could be understood as a request, by mistake.There are 51 RACH-blocks in 240ms (approx)
so that’s 765,000 RACH blocks / hour
0.02% * 765,000 = 153 ghost rach per hour are “accepted” by 3GPP. In other words, if a BTS is located in an area without any traffic (anechoic room, for example), the number of ghost RACH self-generated should be less than 153 / hour.regards
pixDear PIX,
Can you please shed some light on that matter that for a request to be considered as RACH it should GMSK modulated & BSIC needs to be decoded to consider it as RACH request.
It means Ghost rach should happen only in rare cases.
Looking for your reply.
Thanks
BR,
BHTis anybody got break through to the SD blocking due to ghost RACH /Faulty MS
BHT,
sory, i missed your post.
Rach requests do not contain the BSIC.
Yes, they are GMSK modulated. But that doesn’t allow noise detection. EM Noise could “sound” like a GMSK signal.Yes, Ghost RACH are rare, if they are just noise. But sometimes, some equipments generates a signal which is exactly containing a sequence of 900MHz phase modulated symbols. In this casse, it is decoded as a RACH.
Regards
pix
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