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# relation between wcdma channel bandwidth and channel capacity ?

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#### nitink19

##### Newbie level 3
Hi everyone,

I want to know that channel badwidth of 5MHz in case of WCDMA and data rate or chip rate of 3.84Mcps are somehow related ?
If yes then what is the relation ?
One relation I have come across is Shannon's Relation but in that case we also need to know the SNR to calculate the data rate ?

Say 16QAM, the spectrum efficiency is 4bit/s/Hz, so for bandwidth 3.5MHz, the channel capacity is 14Mbit/s.

Say 16QAM, the spectrum efficiency is 4bit/s/Hz, so for bandwidth 3.5MHz, the channel capacity is 14Mbit/s.

Actually i am a newcomer in the telecom domain and have been hearing about channel bandwidth 5MHz and corresponding data rate 3.84Mcps in WCDMA so i am confused about the relation between these two figures and have not yet been able to think beyond ...

in the information theory we have the Shannon's theorems.
it states:
C = BW. log(1+SNR) i.e; capacity of the channel is related to bandwidth and SNR of the signal and noise.

so my query is like this data rate(3.84Mcps) is coming from this relation where BW is 5 MHz ?
If yes then what value of SNR is assumed ?
If not then where is this data rate(3.84 Mcps) coming from ?

I suggest you find a telecomm textbook to check the answers.
I alomst forgot it because I studied it 16 years ago and didn't use it until now.
The Shannon equation describe the maximum capacity limit in theory, but in fact for CDMA, say 5MHz and 3.84Mcps, it is far below the Shannon capacity.
So in fact the capacity is different.
And for a BW=5MHz spectrum, the spectrum width is only about 3.84MHz, there must be some tolerance for BW to meet the MASK of 3GPP etc.

Any good telecom book u can suggest ???

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