METHOD AND SYSTEM FOR MULTIBAND USER SCHEDULING IN A MULTIPLE USER MULTIPLE INPUT MULTIPLE OUTPUT (MU-MIMO) COMMUNICATION SYSTEM
A method and system for multiband user scheduling in a multiple user multiple input multiple output (MU-MIMO) communication system are presented. In one aspect of the method and system a plurality of users in a user group may be selectively assigned to individual frequency bands among a plurality of frequency bands (referred to as a multiband). In an exemplary aspect, a modified greedy user scheduling algorithm may be utilized for assigning users, selected from the user group, to each of the frequency bands. Assigned users for a given frequency band are determined based on channel norm values computed for each of the users in the user group and on chordal distances computed between users in the user group. Pairs of users, selected from the user group, are assigned to each frequency band in the multiband to maximize aggregate data rate capacity for the MIMO communication system.
1 . A method for processing signals, the method comprising:
performing by one or more processors and/or circuits:
for each of a plurality of frequency bands in a multiband:
computing a channel norm value, for a current frequency band in said multiband, for each of a plurality of users in a users group;
selecting a plurality of candidate users from said plurality of users based on said computed plurality of channel norm values;
computing a chordal distance value, for said current frequency band, for each of a remainder of said plurality of users, wherein said remainder of said plurality of users excludes said plurality of candidate users;
selecting a subsequent plurality of candidate users from said remainder of said plurality of users based on said computed plurality of chordal distance values; and
scheduling a plurality of assigned users for said current frequency band, wherein said plurality of assigned users is chosen from said selected plurality of candidate users and/or said selected subsequent plurality of candidate users.
2 . The method according to claim 1 , comprising determining a maximum channel norm value, a second largest channel norm value and a third largest channel norm value for said current frequency band.
3 . The method according to claim 2 , wherein a first candidate user corresponds to said maximum channel norm value, a second candidate user corresponds to said second largest channel norm value, and a third candidate user corresponds to said third largest channel norm value.
4 . The method according to claim 3 , wherein said plurality of candidate users comprises said first candidate user, said second candidate user and said third candidate user.
5 . The method according to claim 3 , comprising computing a first candidate chordal distance value, determined relative to said first candidate user, for said each of said remainder of said plurality of users.
6 . The method according to claim 5 , comprising determining a maximum chordal distance value based on said computed plurality of first candidate chordal distance values.
7 . The method according to claim 6 , comprising determining a first subsequent candidate user based on said determined maximum chordal distance value.
8 . The method according to claim 7 , comprising computing a second candidate chordal distance value, determined relative to said second candidate user, for each of a portion of said remainder of said plurality of users, wherein said portion of said remainder of said plurality of users excludes said first subsequent candidate user.
9 . The method according to claim 8 , comprising determining a subsequent maximum chordal distance value based on said computed plurality of second candidate chordal distance values.
10 . The method according to claim 9 , comprising determining a second subsequent candidate user based on said determined subsequent maximum chordal distance value.
11 . The method according to claim 10 , wherein said subsequent plurality of candidate users comprises said first subsequent candidate user and said second subsequent candidate user.
12 . The method according to claim 1 , comprising removing said plurality of assigned users, for said current frequency band, from said user group.
13 . The method according to claim 12 , comprising selecting a subsequent frequency band from said multiband.
14 . A system for processing signals, the system comprising:
one or more circuit that enable, for each of a plurality of frequency bands in a multiband:
computation of a channel norm value, for a current frequency band in said multiband, for each of a plurality of users in a users group;
selection of a plurality of candidate users from said plurality of users based on said computed plurality of channel norm values;
computation of a chordal distance value, for said current frequency band, for each of a remainder of said plurality of users, wherein said remainder of said plurality of users excludes said plurality of candidate users;
selection of a subsequent plurality of candidate users from said remainder of said plurality of users based on said computed plurality of chordal distance values; and
scheduling of a plurality of assigned users for said current frequency band, wherein said plurality of assigned users is chosen from said selected plurality of candidate users and/or said selected subsequent plurality of candidate users.
15 . The system according to claim 14 , wherein said one or more circuits enable determination of a maximum channel norm value, a second largest channel norm value and a third largest channel norm value for said current frequency band.
16 . The system according to claim 15 , wherein a first candidate user corresponds to said maximum channel norm value, a second candidate user corresponds to said second largest channel norm value, and a third candidate user corresponds to said third largest channel norm value.
17 . The system according to claim 16 , wherein said plurality of candidate users comprises said first candidate user, said second candidate user and said third candidate user.
18 . The system according to claim 16 , wherein said one or more circuits enable computation of a first candidate chordal distance value, determined relative to said first candidate user, for said each of said remainder of said plurality of users.
19 . The system according to claim 18 , wherein said one or more circuits enable determination of a maximum chordal distance value based on said computed plurality of first candidate chordal distance values.
20 . The system according to claim 19 , wherein said one or more circuits enable determination of a first subsequent candidate user based on said determined maximum chordal distance value.
21 . The system according to claim 20 , wherein said one or more circuits enable computation of a second candidate chordal distance value, determined relative to said second candidate user, for each of a portion of said remainder of said plurality of users, wherein said portion of said remainder of said plurality of users excludes said first subsequent candidate user.
22 . The system according to claim 21 , wherein said one or more circuits enable determination of a subsequent maximum chordal distance value based on said computed plurality of second candidate chordal distance values.
23 . The system according to claim 22 , wherein said one or more circuits enable determination of a second subsequent candidate user based on said determined subsequent maximum chordal distance value.
24 . The system according to claim 23 , wherein said subsequent plurality of candidate users comprises said first subsequent candidate user and said second subsequent candidate user.
25 . The system according to claim 14 , wherein said one or more circuits enable removal of said plurality of assigned users, for said current frequency band, from said user group.
26 . The system according to claim 25 , wherein said one or more circuits enable selection of a subsequent frequency band from said multiband.