Data equalisation in a communication receiver wth transmit and receive diversity
View Patent ↗A method of performing data equalization in a communication receiver with transmit and receive diversity includes (a) for each i-th receiver antenna and j-th transmitter antenna, calculating a channel response matrix H i,j from multi-path channel estimates, (b) each i-th receiver antenna, calculating a channel gain matrix G i from the channel response matrices H i,j and a scalar noise factor β, (c) calculating the middle column c 0 of G i −1 , (d) calculating a filter coefficient vector w i,j from the middle column c 0 of G i −1 of and the Hermitian transpose H i,j H of the corresponding channel response matrices H i,j , (e) filtering input data r i received at each i-th receiver antenna with the corresponding filter coefficient vectors w i,j , (f) despreading the filtered input data from each i-th receiver antenna, (g) applying phase compensation to the despread data, and (h) combining the despread data from all antennas to obtain received equalized data.
1. A method for performing data equalisation in a communication receiver, the communication receiver forming part of a communication system with transmit and receive diversity, the method including the steps of:
(a) for each i-th receiver antenna and j-th transmitter antenna, calculating a channel response matrix H i,j from multi-path channel estimates;
(b) each i-th receiver antenna, calculating a channel gain matrix G i from the channel response matrices H i,j and a scalar noise factor β;
(c) calculating the middle column c 0 of the inverse G i −1 of the channel gain matrix G i ;
(d) calculating filter coefficient vectors w i,j from the middle column c 0 of the inverse G i −1 of the channel gain matrix G i and the Hermitian transpose H i,j H of the corresponding channel response matrices H i,j ;
(e) filtering input data r i received at each i-th receiver antenna with the corresponding filter coefficient vectors w i,j ;
(f) despreading the filtered input data from each i-th receiver antenna;
(g) applying phase compensation to the despread data; and
(h) combining the despread data from all antennas to obtain received equalised data.
2. A method according to claim 1 , wherein step (c) includes:
(h) performing a Cholesky decomposition of each channel gain matrix G i into a lower triangular matrix L and an upper triangular matrix U;
(i) performing forward substitution on the lower triangular matrix L to calculate a column vector d; and
(j) performing backward substitution on the column, vector d and the Hermitian transpose L H of the lower triangular matrix L to calculate the middle column c 0 of the inverse G i −1 of the channel gain matrix G i .
3. A method according to claim 1 , wherein the channel gain matrix G i to be inverted is calculated from the expression
G
i
=
∑
1
j
H
^
i
,
j
H
H
^
i
,
j
+
β
~
i
I
where I is the identity matrix.
4. A chip equaliser for use in a communication receiver forming part of a communication system with transmit and receive diversity, the chip equaliser including one or more computational blocks for carrying out a method according to claim 1 .
5. A method according to claim 2 , wherein the channel gain matrix G i to be inverted is calculated from the expression
G
i
=
∑
1
j
H
^
i
,
j
H
H
^
i
,
j
+
β
~
i
I
where I is the identity matrix.
6. A chip equaliser for use in a communication receiver forming part of a communication system with transmit and receive diversity, the chip equaliser including one or more computational blocks for carrying out a method according to claim 2 .
7. A chip equaliser for use in a communication receiver forming part of a communication system with transmit and receive diversity, the chip equaliser including one or more computational blocks for carrying out a method according to claim 3 .
8. A chip equaliser for use in a communication receiver forming part of a communication system with transmit and receive diversity, the chip equaliser including one or more computational blocks for carrying out a method according to claim 5 .