OFDMA with adaptive subcarrier-cluster configuration and selective loading

1. A method, comprising:

transmitting, at a first time by a base station, at least a first pilot symbol to a subscriber unit for measuring the at least first pilot symbol and obtaining first channel and interference information for a plurality of orthogonal frequency division multiple access (OFDMA) subcarriers;

receiving, by the base station from the subscriber unit, after the transmitting of the at least first pilot symbol to the subscriber unit, first feedback of channel and interference information relating to a plurality of groups, each group of the plurality of groups having a plurality of clusters, each cluster of the plurality of clusters having at least two OFDMA subcarriers of the plurality of OFDMA subcarriers;

transmitting, by the base station to the subscriber unit, a first allocation of at least one cluster of the plurality of clusters selected by the base station for use by the subscriber unit, after, and based on at least the receiving of the first feedback of channel and interference information;

transmitting, at a second time after the first time, by the base station, at least a second pilot symbol to the subscriber unit for measuring the at least second pilot symbol and obtaining second channel and interference information for the plurality of OFDMA subcarriers;

receiving, by the base station from the subscriber unit, after the transmitting of the at least second pilot symbol to the subscriber unit, second feedback of channel and interference information relating to the plurality of groups; and

transmitting, by the base station to the subscriber unit, a second allocation of at least another cluster of the plurality of clusters selected by the base station for use by the subscriber unit, after, and based on at least the receiving of the second feedback of channel and interference information.

2. The method of claim 1 , further comprising transmitting, by the base station to the subscriber unit, a retraining request.

3. The method of claim 2 , wherein the second feedback of channel and interference information is received after the transmitting of the retraining request.

4. The method of claim 1 , wherein at least one OFDMA subcarrier of the first allocation of the at least one cluster of the plurality of clusters is non-contiguous with other OFDMA subcarriers of the first allocation of the at least one cluster of the plurality of clusters.

5. The method of claim 1 , wherein at least one of the first feedback of channel and interference information and the second feedback of channel and interference information includes an indication of a modulation and coding rate.

6. The method of claim 1 , wherein the first feedback of channel and interference information and the second feedback of channel and interference information include signal-to-interference-plus-noise ratio (SINR) information for at least one group of the plurality of groups.

7. The method of claim 6 , wherein the subscriber unit has a fixed association with the plurality of groups, such that group identifier information to identify groups associated with the SINR information is not necessary.

8. The method of claim 1 , wherein the first allocation of the at least one cluster of the plurality of clusters includes an indication of a modulation and coding rate associated with the first allocation of the at least one cluster of the plurality of clusters.

9. The method of claim 1 , wherein the second allocation of the at least another cluster of the plurality of clusters includes an indication of a modulation and coding rate associated with the second allocation of the at least another cluster of the plurality of clusters.

10. The method of claim 1 , wherein the first feedback of channel and interference information and the second feedback of channel and interference information each relate to all groups of the plurality of groups.

11. The method of claim 1 , wherein each of the at least first and second pilot symbols occupies an entire orthogonal frequency division multiplexing (OFDM) frequency bandwidth.

12. A base station, comprising:

a transceiver configured to:

transmit, at a first time, at least a first pilot symbol to a subscriber unit for measuring the at least first pilot symbol and obtaining first channel and interference information for a plurality of orthogonal frequency division multiple access (OFDMA) subcarriers;

receive, from the subscriber unit, after the transmission of the at least first pilot symbol to the subscriber unit, first feedback of channel and interference information relating to a plurality of groups, each group of the plurality of groups having a plurality of clusters, each cluster of the plurality of clusters having at least two OFDMA subcarriers of the plurality of OFDMA subcarriers;

transmit, to the subscriber unit, a first allocation of at least one cluster of the plurality of clusters selected by the base station for use by the subscriber unit, after, and based on at least the receipt of the first feedback of channel and interference information;

transmit, at a second time after the first time, at least a second pilot symbol to the subscriber unit for measuring the at least second pilot symbol and obtaining second channel and interference information for the plurality of OFDMA subcarriers;

receive, from the subscriber unit, after the transmission of the at least second pilot symbol to the subscriber unit, second feedback of channel and interference information relating to the plurality of groups;

and

transmit, to the subscriber unit a second allocation of at least another cluster of the plurality of clusters selected by the base station for use by the subscriber unit, after, and based on at least the receipt of the second feedback of channel and interference information.

13. The base station of claim 12 , wherein the transceiver is further configured to transmit, to the subscriber unit, a retraining request.

14. The base station of claim 13 , wherein the receipt of the second feedback of channel and interference information occurs after the transmission of the retraining request.

15. The base station of claim 12 , wherein at least one OFDMA subcarrier of the first allocation of the at least one cluster of the plurality of clusters is non-contiguous with other OFDMA subcarriers of the first allocation of the at least one cluster of the plurality of clusters.

16. The base station of claim 12 , wherein at least one of the first feedback of channel and interference information and the second feedback of channel and interference information includes an indication of a modulation and coding rate.

17. The base station of claim 12 , wherein the first feedback of channel and interference information and the second feedback of channel and interference information include signal-to-interference-plus-noise ratio (SINR) information for at least one group of the plurality of groups.

18. The base station of claim 17 , wherein the subscriber unit has a fixed association with the plurality of groups, such that group identifier information to identify groups associated with the SINR information is not necessary.

19. The base station of claim 12 , wherein the first allocation of the at least one cluster of the plurality of clusters includes an indication of a modulation and coding rate associated with the first allocation of the at least one cluster of the plurality of clusters.

20. The base station of claim 12 , wherein the second allocation of the at least another cluster of the plurality of clusters includes an indication of a modulation and coding rate associated with the second allocation of the at least another cluster of the plurality of clusters.

21. The base station of claim 12 , wherein the first feedback of channel and interference information and the second feedback of channel and interference information each relate to all groups of the plurality of groups.

22. The base station of claim 12 , wherein each of the at least first and second pilot symbols occupies an entire orthogonal frequency division multiplexing (OFDM) frequency bandwidth.