- This topic has 17 replies, 1 voice, and was last updated 13 years, 4 months ago by pix.
12th November 2007 at 12:44 #49658danaGuest
it could be a silly question for, but I am an electronics engineer, and recently I am a trainee in commnications..
i wanna to ask why the BER must be less than -110dbm?? i.e why the sum of errors in bins 5,6and 7 must be less than errors in bin_0 ??? that’s my question…
regards12th November 2007 at 21:52 #49659pixGuest
i don’t understand your question, but the BER is a rate (in percentage), and “-110 dBm” is a measured power, in decibel-milliwatt. So the BER cannot be compared with dBm.
Regarding the bins, i don’t know.
regards,15th November 2007 at 09:17 #49660danaGuest
I know my error..
regards..20th December 2007 at 14:59 #49661ashish tewariGuest
hi, can any one please explain me
why down link frequency is higher then up link frequency……20th December 2007 at 19:09 #49662pixGuest
downlink and uplink had to use different bands, so one of them had to be higher and the other lower. I don’t think there is a logical explanation for it. It’s random…
Some might say that uplink on the lower band allows a better radio propagation (low freq propagates better than high freq).
Yet, the benefit is about 0.5dB, as far as i recall… neglictible !!23rd December 2007 at 16:11 #49663liujunGuest
because higher frequency has more large pathloss than lower frequency, BTS(nodeB) has a larger output power than MS(UE).so
down link frequency is higher then up link frequency.24th December 2007 at 07:43 #49664pixGuest
liujun : neglictible !29th December 2007 at 16:27 #49665liujunGuest
what’s mean about neglictible.29th December 2007 at 17:21 #49666pixGuest
the gain of pathloss between ul and dl is very small : it is not useful in real life !
that’s what I mean with “neglictible”. But that’s just my opinion…30th December 2007 at 07:43 #49667liujunGuest
up link coverage limted in GSM/UMTS commercial network sometime will be occured.30th December 2007 at 18:42 #49668pixGuest
yes, most of GSM sites are uplink limited, you are right.
–> The benefit of the uplink band being lower than the downlink band is not useful…1st January 2008 at 15:57 #49669liujunGuest
thanks. may be the frequence question of UL and DL need to be solved by RF equpment designer. hehe.7th January 2008 at 11:21 #49670amiGuest
I think the reason behind it is lower freq. has a large wavelength than the higher freq.so it can travel large area with low power(as in MS)compaired to BTS.7th January 2008 at 16:05 #49671pixGuest
Ami, I am very very sad you
posts…8th January 2008 at 15:52 #49672telecom72Guest
Uplink frequencies in mobile systems are always the lower band of frequencies, because it requires less power to transmit a lower frequency over a given distance and this saves valuable power of the MSs