## Thursday, February 9, 2012

### DUST

DUST stands for Differential Unitary Space Time coding. This coding method is used in the transmission of information from multiple antennas to multiple antennas.

The transmission of information in a block can be modelled with the following equation

$X = \sqrt{\rho} S H + W$

where S is the input matrix, H is the channel matrix, \rho is a scalar coefficient that modulates the channel and W is the noise.

DUST encodes the information in a unitary matrix U_n, which is indirectly encoded through a sequence of two S unitary blocks as

$S_n = U_n S_{n-1}$

If H is full-rank and the channel does not change significantly in the time the two blocks are transmitted. The unitary matrix U can be recovered from the sequence of two received unitary blocks X without! the need to know the channel H as

$X_n = U_n X_{n-1} + W_n^{\prime}$

where the new noise is defined as
$W_n^{\prime} = W_n - U_n W_{n-1}$