Group decoder with improved partitioning for multiple antenna multiuser channel
A group detection arrangement for a multiple antenna receiver structure usable with a multiuser multiple access communication channel with fading is herein disclosed. The group detection arrangement uses an optimized channel dependent group partitioning technique.
1. A method for mapping a given set of users with predetermined transmission rates and powers into an ordered partition for use in a multiple antenna receiver structure employing a successive group decoder and comprising:
(i) selecting a group or subset from a set of users that maximizes a metric among all groups having a size less than a specified maximum group size when treating the remaining users as interferers;
(ii) appending the selected group into an ordered partition and removing the users in the selected group from the set of users; and
(iii) repeating steps (i) and (ii) until the set of users is empty;
the metric for a candidate group G of users when treating the users in the set S\G as interferers being based on
M
(
G
)
=
min
J
⊆
G
log
I
+
(
H
~
J
)
*
(
I
+
H
~
S
\
G
(
H
~
S
\
G
)
*
)
-
1
H
~
J
∑
k
∈
J
R
k
where J is a subset of the set G, I is the identity matrix, {tilde over (H)} J includes channel realizations and transmit powers for users in the set J, {tilde over (H)} S/G includes the channel realizations and transmit powers for users in the set S\G, and R k is the specified rate of user k.
2. The method of claim 1 wherein the metric is responsive to a candidate group or subset of users, a set of interfering users, the rates assigned to the candidate group of users and the channel estimates and transmit powers corresponding to all users in the candidate group and the set of interfering users.
3. The method of claim 1 wherein the maximum group size parameter is fixed and provided as an input.
4. The method of claim 1 wherein the metric for a candidate group G of users when treating the users in the set S\G as interferers is given by
M
(
G
)
=
min
J
⊆
G
{
log
I
+
(
H
~
J
)
*
(
I
+
H
~
S
\
G
(
H
~
S
\
G
)
*
)
-
1
H
~
J
-
∑
k
∈
J
R
k
}
.
5. The method of claim 1 wherein the maximum group size parameter is channel dependent.
6. The method of claim 5 wherein the maximum group size parameter cannot exceed a specified upper bound.
7. The method of claim 6 wherein the maximum group size parameter is chosen to be the smallest one that avoids an outage.
8. A method for mapping a given set of users with pre-determined transmission rates and powers into a partition for use in a multiple antenna receiver structure employing a group decoder without feedback (parallel group decoder) and comprising:
i. determining the metric of a partition as the minimum of the metrics of its constituent groups; and
ii. selecting a partition that maximizes a metric among all partitions for whom none of their constituent groups can be combined without violating a specified maximum group size;
said metric for a group G of users when treating all the other users in the set G c as interferers being based on
M
(
G
)
=
min
J
⊆
G
log
I
+
(
H
~
J
)
*
(
I
+
H
~
G
c
(
H
~
G
c
)
*
)
-
1
H
~
J
∑
k
∈
J
R
k
.
where J is a subset of the set G, I is the identity matrix, {tilde over (H)} J includes the channel realizations and transmit powers for users in the set J, {tilde over (H)} G c includes the channel realizations and transmit powers for users in the set G c and R k is the specified rate of user k.
9. The method of claim 8 wherein the metric for a candidate group G of users when treating all the other users in the set G c as interferers is given by
M
(
G
)
=
min
J
⊆
G
{
log
I
+
(
H
~
J
)
*
(
I
+
H
~
S
\
G
(
H
~
S
\
G
)
*
)
-
1
H
~
J
-
∑
k
∈
J
R
k
}
.