- This topic has 5 replies, 1 voice, and was last updated 10 years, 9 months ago by pix.
30th June 2010 at 12:01 #63356RiMiGuest
I am beginner in GSM tech , so having some doubts. Can anybody please explain me “Co-channel & adjacent channel interferce” .
And how does cell identifies that which frequency is offering interference?
Hi pix looking forward to see your reply.
Thanx in advance…….30th June 2010 at 19:13 #63357pixGuest
as you know, one call is using one specific frequency during one/eight of the time.
if somewhere else in the area, another call is using the same frequency during the same time, the first user will hear a degradation in the voice quality (robot voice).
this is co-channel interference.
2 calls using the same frequency, in the same area.
if there are 8 users on the first frequency, and 8 users on the second frequency, you see that the probability of “collision” is very high.
now, same scenario, except that the second user is using a frequency which is +200kHz or -200kHz compared to the 1st frequency. Here, the impact on the voice is much less : only if this “adjacent” frequency is very very strong, then the first frequency will be “eclipsed” and the first subscriber will hear a bad voice quality (still the robot voice).
the cell doesn’t identify the interference, it is up to the optimizer to find which frequencies are conflicting.
pix1st July 2010 at 07:13 #63358RiMiGuest
Thanx a lot Pix for your quick response,
can you please tell me how does optimizer find this out, that which frequency is interfering with the original one?
RiMi1st July 2010 at 11:33 #63359pixGuest
by checking which cells are using the same frequency in the vicinity, on the map, and trying to guess which one is actually propagating up to where the intereference was detected.
pix3rd July 2010 at 14:51 #63360RiMiGuest
i wanted to knw which BCCH frequency is interfering with the oiginal one….? how would optimizer find this? could you please tell me abt the procedural steps is there is any!!!
Thanx for all your response and help!!!!!!!!!
RiMi3rd July 2010 at 19:38 #63361pixGuest
this is what i’ve explained in my previous post..