Dynamic subchannel and bit allocation in a multiuser-MIMO/OFDMA system
View Patent ↗A resource allocation method in a multiuser-multiple-input multiple-output/orthogonal frequency division multiple access (MIMO/OFDMA) system. In the multiuser-MIMO/OFDMA system feedback information is received from terminals. A channel gain and a transmission rate for each user are determined using the feedback information. An average channel gain for each user is computed according to the channel gain. The average number of bits for each user is determined according to the average channel gain. The number of subchannels for each user is computed according to the average number of bits for each user. At least one subchannel is allocated to each user according to the number of subchannels for each user. A modulation scheme for each of the at least one subchannel is determined. The resource allocation method adaptively allocates subchannels and bits according to channel environment, thereby considerably improving frequency use efficiency as well as a power gain.
1. A resource allocation method in a multiple-input multiple-output/orthogonal frequency division multiple access (MIMO/OFDMA) system including a base station for transmitting signals through a plurality of transmitter antennas, and a plurality of terminals for receiving the signals through receiver antennas, the method comprising:
determining, at the base station upon receipt of feedback information, at least one of a channel gain and transmission rate for each user terminal;
computing an average channel gain for each said user terminal according to the determined channel gain;
determining an average number of bits for each said user terminal using the determined average channel gain;
determining a number of subchannels for each said user terminal according to the determined average number of bits for each said user terminal; and
allocating a modulating scheme for each subchannel according to the determined number of subchannels;
wherein the average channel gain is computed differently for each said user terminal according to one of a multiuser-MIMO/OFDMA environment, a multiuser-multiple-input single-output (MISO)/OFDMA environment, and a single-user MIMO/OFDMA environment.
2. The resource allocation method according to claim 1 , wherein the average channel gain for each said user terminal in the multiuser-MIMO/OFDMA environment is computed by:
α
k
2
(
l
)
=
1
N
(
K
-
1
)
∑
n
=
1
N
∑
p
=
1
,
p
≠
k
K
α
k
2
(
n
,
l
,
p
)
,
where K is a total number of user terminals, N is a total number of subcarriers, k and p are user terminal indices, and l is a MIMO subchannel index.
3. The resource allocation method according to claim 1 , wherein the average channel gain for each said user terminal in the multiuser-MISO/OFDMA environment is computed by:
α
k
2
(
l
)
=
1
N
(
K
-
1
)
∑
n
=
1
N
∑
p
=
1
,
p
≠
k
K
α
k
2
(
n
,
p
)
,
where K is a total number of user terminals, N is a total number of subcarriers, and k and p are user terminal indices.
4. The resource allocation method according to claim 1 , wherein the average channel gain for each said user terminal in the single-user-MIMO/OFDMA environment is computed by:
α
k
2
(
l
)
=
1
N
∑
n
=
1
N
α
k
2
(
n
,
l
)
,
where N is a total number of subcarriers, and l is a MIMO subchannel index.
5. The resource allocation method according to claim 1 , wherein the average channel gain for each said user terminal is computed by:
α
k
2
(
l
)
=
1
N
(
K
-
1
)
∑
n
=
1
N
∑
p
=
1
,
p
≠
k
K
α
k
2
(
n
,
l
,
p
)
in a multiuser-MIMO/OFDMA environment, is computed by:
α
k
2
(
l
)
=
1
N
(
K
-
1
)
∑
n
=
1
N
∑
p
=
1
,
p
≠
k
K
α
k
2
(
n
,
p
)
in a multiuser-multiple-input single-output (MISO)/OFDMA environment, and is computed by:
α
k
2
(
l
)
=
1
N
∑
n
=
1
N
α
k
2
(
n
,
l
)
in a single-user-MIMO/OFDMA environment,
where K is a total number of user terminals, N is a total number of subcarriers, k and p are user terminal indices, and l is a MIMO subchannel index.
6. The resource allocation method according to claim 1 , wherein the number of subchannels for each said user terminal is computed using Vogel's method, which is modified such that additional constraints are taken into account in a multiuser-MIMO/OFDMA environment, and a multiuser-multiple-input single-output (MISO)/OFDMA environment.
7. The resource allocation method according to claim 1 , wherein the number of subchannels for each said user terminal is computed using Vogel's method in a single-user-MIMO/OFDMA environment.
8. The resource allocation method according to claim 1 , wherein the number of subchannels for each said user terminal is computed using Vogel's method, which is modified such that additional constraints are taken into account in a multiuser-MIMO/OFDMA environment.
9. The resource allocation method according to claim 1 , wherein the number of subchannels for each said user terminal is computed using Vogel's method, which is modified such that additional constraints are taken into account in a multiuser-multiple-input single-output (MISO)/OFDMA environment.
10. The resource allocation method according to claim 1 , wherein the number of subchannels for each said user terminal is computed using Vogel's method, which is modified such that additional constraints are taken into account in a single-user-MIMO/OFDMA environment.