Simulation of a Multiple Input Multiple Output (MIMO) system using various Space Time Coding (STC) techniques in LabVIEW
(Undergraduation Major Project Thesis)

Click Here to  view the top level graphical user interface of the MIMO Simulation Model.

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Download the stand-alone software developed as a part of the undergraduate thesis.

Required: LabVIEW Runtime Engine 2009 or later

MIMO Simulation Model.rar MIMO Simulation Model.rar
Size : 2.351 Kb
Type : rar

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Showing category "Theory" (Show all posts)

Generalized Complex Orthogonal Space Time Block Codes

Posted by Ujjval Shah on Tuesday, April 14, 2009, In : Theory 
Some important results:

  1. Rate one generalized complex orthogonal designs do not exist for more than two transmit antennas
  2. The rate of a generalized complex orthogonal design cannot exceed R = 3/4 for more than two antennas
  3. Rate half, R = 0.5, generalized complex orthogonal designs exist for any number of transmit antennas 
  4. For a generator matrix for a given rate and number of antennas, a generator matrix of same rate for number of tranmist antennas less by one can be obtained by simply removin...

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Spatial Multiplexing

Posted by Ujjval Shah on Friday, April 3, 2009, In : Theory 
Till now most of the concentration was on diversity gains achieved by using both transmit and receive antennas in a multiple-input multiple-output (MIMO) channel. However, multiple transmit antennas can be utilized to achieve other goals as well. A higher capacity and as a result a higher transmission rate is possible by increasing the number of transmit antennas. Assume a MIMO channel with equal number of transmit and receive antennas. Then in a rich scattering environment the capacity incre...

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RX Diversity

Posted by Ujjval Shah on Saturday, March 28, 2009, In : Theory 
RX Diversity means to have multiple antennas at the receiver.

There are basically three types of method to obtain RX Diversity:

  1. Selection Combining (SC): Here the receiver selects the best branch of all the receiver antennas and decodes the signal coming from that antenna. It is suboptimal and doesnt utilizes the energy of the signals from the other antennas.
  2. Maximal Ratio Combining (MRC): Here, the limitation of the SC technique is removed. In MRC, signals from all the antennas are weighted app...

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Maximum Likelihood Detection and Receiver

Posted by Ujjval Shah on Friday, February 27, 2009, In : Theory 

The received signals at a receiver antenna in two time slots can be written as:

For more than two antennas, the  max lik rec function will be



...
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Orthogonal Space-Time Block Codes (OSTBC)

Posted by Ujjval Shah on Friday, February 27, 2009, In : Theory 

The goal of space-time coding is to achieve the maximum diversity of NM, the maximum coding gain, and the highest possible throughput. In addition, the decoding complexity is very important.

Alamouti code

N = 2 M = 1

To transmit b bits/cycle, we use a modulation scheme that maps every b bits to one symbol from a constellation with 2bsymbols

First, the transmitter picks two symbols from the constellation using a block of 2b bits. If s1 and s2 are the selected symbols for a block...


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Maximum Ratio Combining (MRC)

Posted by Ujjval Shah on Friday, February 27, 2009, In : Theory 

M receiver antennas receive M signals each represented as:

rm = αms + ηm,

where ηm is a white Gaussian noise sample added to the mth copy of the signal. A maximum-likelihood (ML) decoder combines these M received signals to find the most likely transmitted signal.We consider a coherent detection scheme where the receiver knows the channel path gains, αm. 

Owing to its array gain, MRC typically achieves a few dB better SNR than does SC.

 

...
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Combining Methods

Posted by Ujjval Shah on Friday, February 27, 2009, In : Theory 

The source of diversity does not affect the method of combination with the exception of transmit antenna diversity. For example, receiving two versions of the transmitted signal through polarization diversity is the same as receiving two signals from two receive antennas for the purpose of combining

 There are two main combining methods that are utilized at the receiver:

  •  Maximum Ratio Combining (MRC)
  • Selection Combining

...
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Probability Error

Posted by Ujjval Shah on Friday, February 27, 2009, In : Theory 

Probability Error for Diversity

P= c1e-c2 γ

γ –snr

in fading without diversity


In fading with diversity of NtxNr=Nd


Probability Error for Array Gain


...
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Diversity Methods

Posted by Ujjval Shah on Friday, February 27, 2009, In : Theory 

The replica of the transmitted signal can be sent through different means [99]. For example, it can be transmitted in a different time slot, a different frequency, a different polarization, or a different antenna. The goal is to send two or more copies of the signal through independent fades. Then, since it is less likely to have all the independent paths in deep fades, using appropriate combining methods, the probability of error will be lower.

  •  Time slot – repetition
  • Frequency – fdd
  • Pol...


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Diversity

Posted by Ujjval Shah on Friday, February 27, 2009, In : Theory 

The main idea behind “diversity” is to provide different replicas of the transmitted signal to the receiver. If these different replicas fade independently, it is less probable to have all copies of the transmitted signal in deep fade simultaneously. Therefore, the receiver can reliably decode the transmitted signal using these received signals. This can be done, for example, by picking the signal with the highest SNR or by combining the multiple received signals. As a result, the probabi...


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