What's the difference between quantized CSI and normal CSI?

[urwelcome]

Dear friends,

hope all r fine n fit ,

could somebody brief me about the quantized channel state information actually i dont understand the purpose of word quantized what is difference between normal CSI and quantized channel state information.

thanks in advance

 

[changfa]

Re: quantized CSI

CSI is generally measured by receiver and this information is needed to be fed back to transmitter to enable some functions, e.g., channel-dependent scheduling and adaptive modulation, etc. However, the channel strength (or SINR) is a real number. Therefore, this information needs to be quantized (to a few bits) in order to minimize the feedback overhead.

For example, in 1xEV-DO system, 4-bits quantization is applied.

 

[mkhan]

Re: quantized CSI

Hi,

CSI at transmitter is an important issue to achieve many benefits such as high rates, reduction in interference, relaible tranmsision etc.

We want minimum overhead in feedback channel but we also want most accurate CSI at transmitter as well. If transmitter has perfect channel knowledge than all problems in wireless commuincation are solved, but thats hard to get.

Receiver measure its CSI and quantize it, and then send this info to transmitter, thats why quantization is important.

I hope i made my point clear.

MAK