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From: ingrid on 12 Sep 2006 05:39
Hi,

My question is in relation to the simulation of a MIMO-OFDM
simulation. I have been working in the area of MIMO wireless
communications - space - time coding.

I would like to implement a MIMO-OFDM system using the Alamouti code.
Im well aware of how to do a Alamouti code for a MIMO system but am
lost on how to implement the system when OFDM is added.

In the MIMO system the main steps would be

1. Simulate random bits
2. Modulate the bits to give uncoded modulation symbols (QPSK, 4-QAM,
16-QAM etc.)
3. S/P (Serial to Parallel) Conversion of the uncoded moduation
scheme into nt parallel streams (where nt represents the number of
transmitting antennas). This stream is given as an input to a
space-time encoder which does the spatio-temporal coding. Lets refer
to a particular space-time coded matris as X.

4. Received signal is given as, R = H X + N (where H --- Channel
Matrix, N -- AWGN)

5. ML-decoder substitutes different X (from the codebook) and chooses
the particular X which is closest (in the euclidean sense - MSE).

How would the decoding chain change when you have OFDM before MIMO. I
mean how to the uncoded bits finally map to the coded transmission
symbols from the different carriers. If anyone has a matlab code
based implementation of MIMO-PFDM then I would appreciate if he/she
could send it to me.

Best regards

Ingrid
From: Venkat on 18 Sep 2006 05:10
ingrid wrote:
>
>
> Hi,
>
> My question is in relation to the simulation of a MIMO-OFDM
> simulation. I have been working in the area of MIMO wireless
> communications - space - time coding.
>
> I would like to implement a MIMO-OFDM system using the Alamouti
> code.
> Im well aware of how to do a Alamouti code for a MIMO system but am
> lost on how to implement the system when OFDM is added.
>
> In the MIMO system the main steps would be
>
> 1. Simulate random bits
> 2. Modulate the bits to give uncoded modulation symbols (QPSK,
> 4-QAM,
> 16-QAM etc.)
> 3. S/P (Serial to Parallel) Conversion of the uncoded moduation
> scheme into nt parallel streams (where nt represents the number of
> transmitting antennas). This stream is given as an input to a
> space-time encoder which does the spatio-temporal coding. Lets
> refer
> to a particular space-time coded matris as X.
>
> 4. Received signal is given as, R = H X + N (where H --- Channel
> Matrix, N -- AWGN)
>
> 5. ML-decoder substitutes different X (from the codebook) and
> chooses
> the particular X which is closest (in the euclidean sense - MSE).
>
> How would the decoding chain change when you have OFDM before MIMO.
> I
> mean how to the uncoded bits finally map to the coded transmission
> symbols from the different carriers. If anyone has a matlab code
> based implementation of MIMO-PFDM then I would appreciate if he/she
> could send it to me.
>
> Best regards
>
> Ingrid
From: Diogo on 26 Sep 2006 11:22
We have almost the same problem tha Ingrid, then we are implementing
a link level MIMO system over UTRA FDD in downlink. Our doubt is that
we don't know how to connect the symbols generated by the QPSK
transmitter to the channel matrix H to, after that, in the QPSK
receiver, calculate BER metric.

This is to be aplied to several services in the UMTS technology.

Best regards

Diogo

Venkat wrote:
>
>
> ingrid wrote:
>>
>>
>> Hi,
>>
>> My question is in relation to the simulation of a MIMO-OFDM
>> simulation. I have been working in the area of MIMO wireless
>> communications - space - time coding.
>>
>> I would like to implement a MIMO-OFDM system using the Alamouti
>> code.
>> Im well aware of how to do a Alamouti code for a MIMO system
but
> am
>> lost on how to implement the system when OFDM is added.
>>
>> In the MIMO system the main steps would be
>>
>> 1. Simulate random bits
>> 2. Modulate the bits to give uncoded modulation symbols (QPSK,
>> 4-QAM,
>> 16-QAM etc.)
>> 3. S/P (Serial to Parallel) Conversion of the uncoded moduation
>> scheme into nt parallel streams (where nt represents the number
> of
>> transmitting antennas). This stream is given as an input to a
>> space-time encoder which does the spatio-temporal coding. Lets
>> refer
>> to a particular space-time coded matris as X.
>>
>> 4. Received signal is given as, R = H X + N (where H ---
Channel
>> Matrix, N -- AWGN)
>>
>> 5. ML-decoder substitutes different X (from the codebook) and
>> chooses
>> the particular X which is closest (in the euclidean sense -
MSE).
>>
>> How would the decoding chain change when you have OFDM before
> MIMO.
>> I
>> mean how to the uncoded bits finally map to the coded
> transmission
>> symbols from the different carriers. If anyone has a matlab
code
>> based implementation of MIMO-PFDM then I would appreciate if
> he/she
>> could send it to me.
>>
>> Best regards
>>
>> Ingrid
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