UMTS downlink

[tomery]

Hi All,
Im trying to implement the UMTS downlink analyzer in matlab (or uplin
receiver...), I had a problem in the CPICH descramling process, the SC
(P-SCH and S-SCH) are infulencing the CPICH and i cant extract the symbol
correctly. I dont know if the problem is in the Gold Code Generator, or i
the SCH (although the P-SCH and S-SCH are orthogonal to each other for al
the 16 different slots). Is the Gold Code orthogonal to the SCH ?

please help...

Tomer

[3flp]

tomery wrote:
> Hi All,
> Im trying to implement the UMTS downlink analyzer in matlab (or uplink
> receiver...), I had a problem in the CPICH descramling process, the SCH
> (P-SCH and S-SCH) are infulencing the CPICH and i cant extract the symbols
> correctly. I dont know if the problem is in the Gold Code Generator, or in
> the SCH (although the P-SCH and S-SCH are orthogonal to each other for all
> the 16 different slots). Is the Gold Code orthogonal to the SCH ?
>
> please help...
>
> Tomer

Hi Tomer,

The sync channel is not orthogonal to CPICH. However - it is not very
correlated, so you still have despreading gain. The CPICH symbol which
is in the same position as SCH (first in each slot) will appear noisier
than others. How much noisy will of course depend on relative channel
power. BTW, in UMTS the term Gold code is not used anymore. Also, there
are 15 slots per frame, not 16. You are probably working with way out
of date specs. Check the latest actual information on www.3gpp.org. The
information related to scrambling etc. is in the spec number 25.212.

cheers,
3flp