System and method for transmitting uplink control information in an OFDMA communication system

1. A method for transmitting uplink control information in a communication system using an orthogonal frequency division multiple access (OFDMA) scheme, the method comprising the steps of:

determining by a mobile station (MS) a target anchor base station (BS) with which the MS desires to communicate from among an active set of the MS that is communicating with a current anchor BS;

dividing all codewords in the system into a plurality of codeword groups;

selecting a codeword corresponding to the target anchor BS from among the codewords for a fast feedback channel and transmitting, to the current anchor BS, the selected codeword fin requesting a fast cell switching through the fast feedback channel, wherein a first codeword group of the plurality of codeword groups is allocated for identifying at least one anchor BS included in the active set, a second codeword group of the plurality of codeword groups is allocated for transmitting channel quality information, and a third codeword group of the plurality of codeword groups is allocated for transmitting multiple input multiple output (MIMO) mode selection feedback information;

receiving a response for the fast cell switching from the current anchor BS in response to the transmitted codeword; and

switching the target anchor BS to a new anchor BS of the MS according to the response,

wherein codewords of the first codeword group are sequentially allocated to at least one anchor BS included in the active set.

2. The method of claim 1 , wherein the codeword corresponding to the target anchor BS is selected from codeword allocation information received from the current anchor BS.

3. A method for performing fast cell switching in a communication system using an orthogonal frequency division multiple access (OFDMA) scheme, the method comprising the steps of:

dividing all codewords in the system into a plurality of codeword groups;

receiving, from a mobile station (MS), a codeword corresponding to a target anchor BS selected from among the codewords for a fast feedback channel, wherein a first codeword group of the plurality of codeword groups is allocated for identifying at least one anchor BS included in the active set, a second codeword group of the plurality of codeword groups is allocated for transmitting channel quality information, and a third codeword group of the plurality of codeword groups is allocated for transmitting multiple input multiple output (MIMO) mode selection feedback information;

transmitting a response for the fast cell switching to the MS in response to the received codeword; and

switching the target anchor BS to a new anchor BS of the MS according to the fast feedback channel allocation information,

wherein codewords of the first codeword group are sequentially allocated to at least one anchor BS included in the active set.

4. The method of claim 3 , further comprising the step of:

receiving channel quality information of the target anchor BS through the fast feedback channel using at least one codeword of the second codeword group, after repeatedly receiving the codeword.

5. The method of claim 3 , wherein the codeword corresponding to the target anchor BS is received though a switching request message, when there is a need for updating the active set.

6. The method of claim 3 , further comprising the step of:

creating a new active set of the MS by allocating temporary BS identifiers (IDs) to BSs included in the new active set, when the codeword corresponding to the target anchor BS is received.

7. The method of claim 3 , wherein the switching step comprises the steps of:

receiving, from the MS, the codeword corresponding to the target anchor BS and channel quality information of the target anchor BS alternately and repeatedly for a switching period; and

after the reception of the codeword and the channel quality information for the switching period, immediately switching the target anchor BS to the new anchor BS of the MS.

8. A system for transmitting uplink control information in a communication system using an orthogonal frequency division multiple access (OFDMA) scheme, wherein all codewords in the system are divided into a plurality of codeword groups, the system comprising:

a mobile station (MS) for determining a target anchor base station (BS) with which the MS desires to communicate from among an active set of the MS, selecting a codeword corresponding to the target anchor BS from among the codewords for a fast feedback channel and transmitting the selected codeword for requesting a fast cell switching through the fast feedback channel, wherein a first codeword group of the plurality of codeword groups is allocated for identifying at least one anchor BS included in the active set, a second codeword group of the plurality of codeword groups is allocated for transmitting channel quality information, and a third codeword group of the plurality of codeword groups is allocated for transmitting multiple input multiple output (MIMO) mode selection feedback information; and

a current anchor BS communicating with the MS, for transmitting a response for the fast cell switching to the MS in response to the received codeword so that the MS switches the target anchor BS to a new anchor BS of the MS according to the fast feedback channel allocation information,

wherein codewords of the first codeword group are sequentially allocated to at least one anchor BS included in the active set.

9. The system of claim 8 , wherein the MS repeatedly transmits the codeword corresponding to the target anchor BS a predetermined number of times, and transmits channel quality information of the target anchor BS through the fast feedback channel using at least one codeword of the second codeword group, after repeatedly transmitting the codeword.

10. The system of claim 8 , wherein when there is a need for updating the active set, the MS transmits the codeword corresponding to the target answer BS through a switching request message.

11. The system of claim 8 , wherein the current anchor BS creates a new active set of the MS by allocating temporary BS identifiers (IDs) to BSs included in the new active set, when the codeword corresponding to the target anchor BS is received.

12. The system of claim 8 , wherein the MS transmits the codeword corresponding to the target anchor BS and channel quality information of the target anchor BS alternately and repeatedly for a switching period, and immediately switches the target anchor BS to the new anchor BS of the MS, after the reception of the codeword and the channel quality information for the switching period.

13. The method of claim 1 , further comprising:

transmitting channel quality information of the target anchor BS through the that feedback channel using at least one codeword of the second codeword group, after repeatedly transmitting the codeword corresponding to the target anchor BS a predetermined number of times.

14. The method of claim 1 , wherein the codeword corresponding to the target anchor BS is transmitted through a switching request message, when there is a need for updating the active set.

15. The method of claim 1 , wherein the current anchor BS creates a new active set of the MS by allocating temporary BS identifiers (IDs) to BSs included in the new active set, when the codeword corresponding to the target anchor BS is received.

16. The method of claim 1 , wherein the switching step comprises:

transmitting the codeword corresponding to the target anchor BS and channel quality information of the target anchor BS alternately and repeatedly for a switching period; and

immediately switching the target anchor BS to the new anchor BS of the MS, after the reception of the codeword and the channel quality information for the switching period.