Techniques to transmit data rate control signals for multi-carrier wireless systems

1. A method comprising:

determining a data rate control (DRC) value for each of a plurality of forward link carriers of a multi-carrier transmission from a base station, the plurality of DRC values including at least a first DRC value associated with a first carrier of the plurality of forward link carriers and a second DRC value associated with a second carrier of the plurality of forward link carriers;

spreading the first DRC value and the second DRC value;

transmitting, via a reverse link, at least the first spread DRC value via an in-phase (I) channel input to a quadrature spreading block and at least the second spread DRC value via a quadrature-phase (Q) channel input to the quadrature spreading block.

2. The method of claim 1 wherein the determining comprises:

measuring a channel quality parameter for each of the plurality of carriers;

determining a data rate control (DRC) value identifying a data rate for each of the plurality of forward link carriers based on the measuring.

3. The method of claim 2 wherein the measuring comprises:

receiving a pilot signal associated with each of the forward link carriers; and

measuring a signal to-noise-ratio or other channel quality parameter for each pilot signal.

4. The method of claim 1 wherein the spreading comprises spreading the first DRC value and the second DRC value using a Walsh code corresponding to a wireless sector.

5. The method of claim 1 wherein the spreading comprises:

determining a wireless sector from which to receive data via a forward link channel;

spreading the first DRC value and the second DRC value using a Walsh code corresponding to the determined wireless sector.

6. The method of claim 1 wherein the spreading comprises:

determining a Walsh code for each of the forward link carriers;

spreading each DRC value using the Walsh code corresponding to the carrier.

7. The method of claim 6 wherein the spreading comprises spreading each DRC value using a different Walsh code for each of the carriers.

8. The method of claim 1 wherein the spreading comprises:

spreading the first DRC value and the second DRC value using a DRC cover code corresponding to a wireless sector; and

further spreading each spread DRC value using a code corresponding to the carrier for the DRC value.

9. The method of claim 1 wherein the determining comprises determining a first data rate control (DRC) value for a first carrier, a second DRC value for a second carrier, and a third DRC value for a third carrier;

wherein the spreading comprises spreading the first, second and third DRC values; and

wherein the transmitting comprises:

transmitting the first spread DRC value via an in-phase (I) channel input to a quadrature spreading block; and

transmitting the second and third spread DRC values via a quadrature-phase (Q) channel input to the quadrature spreading block.

10. The method of claim 1 wherein the determining comprises determining a first data rate control (DRC) value for a first carrier, a second DRC value for a second carrier, a third DRC value for a third carrier, and a fourth DRC value for a fourth carrier;

wherein the spreading comprises spreading the first, second, third and fourth DRC values; and

wherein the transmitting comprises:

transmitting the first spread DRC value via an in-phase (I) channel input to the quadrature spreading block; and

transmitting the second, third and fourth spread DRC values via a quadrature-phase (Q) channel input to the quadrature spreading block.

11. A wireless apparatus comprising a memory storing software instructions and a controller which together are adapted to cause the wireless apparatus to:

determine data rate control (DRC) values for each of a plurality of forward link carriers of a multi-carrier transmission from a base station, the DRC values including at least a first DRC value associated with a first carrier of the plurality of forward link carriers and a second DRC value associated with a second carrier of the plurality of forward link carriers;

transmit via a reverse link channel at least a first of the DRC values via an in-phase (I) channel input to a quadrature spreading block and at least a second of the DRC values via a Quadrature-phase (Q) channel input to the quadrature spreading block.

12. The wireless apparatus of claim 11 wherein the wireless apparatus is compliant with CDMA2000 EV-DO Revision B/3GPP2 C.S0024-B.

13. The wireless apparatus of claim 11 wherein the apparatus is operating in an asymmetric multicarrier mode in which a number of the forward link carriers used for data transmission is greater than a number of reverse link carriers used to transmit DRC values for the forward link carriers.

14. The wireless apparatus of claim 11 and further comprising:

a bi-orthogonal encoder to encode the DRC values;

a first multiplier to spread the encoded DRC values using a DRC cover code corresponding to a wireless sector; and

a second multiplier to further spread each DRC value using a Walsh code corresponding to the carrier for the DRC value.

15. A wireless apparatus comprising a controller and a memory storing software instructions which together are configured to cause the wireless apparatus to transmit, via a reverse link, at least a first data rate control (DRC) value via an in-phase (I) channel input to a quadrature spreading block and at least a second DRC value via a Quadrature-phase (Q) channel input to the quadrature spreading block, the first DRC value associated with a first forward link carrier and the second DRC value associated with a second forward link carrier, the first and second forward link carriers being part of a multi-carrier transmission from a base station.

16. The wireless apparatus of claim 15 wherein the wireless apparatus is compliant with CDMA2000 EV-DO Revision B/3GPP2 C.S0024-B.

17. The wireless apparatus of claim 15 and further comprising:

a bi-orthogonal encoder to encode the DRC values;

a first multiplier to spread the encoded DRC values using a DRC cover code corresponding to a wireless sector; and

a second multiplier to further spread the first DRC value using a Walsh code corresponding to the first forward link carrier, and to further spread the second DRC value using a Walsh code corresponding to the second forward link carrier.