Method and apparatus for hybrid CDM OFDMA wireless transmission

1. A method of wireless transmission from a mobile unit to a base station, comprising:

multiplexing a pilot signal and a data signal, wherein the data signal operates at a data rate, comprising:

splitting the data signal into a plurality of data streams;

spreading the plurality of data streams and the pilot signal using plurality of orthogonal Walsh codes;

applying a data gain to the plurality of data streams;

applying a pilot gain to the pilot signal, wherein the data gain and the pilot gain are a function of the data rate such that increasing the data rate causes the pilot gain to decrease and the data gain to increase and decreasing the data rate causes the pilot gain to increase and the data gain to decrease;

combining the plurality of data streams and the pilot signal into a multiplexed signal containing both the pilot signal and the data signal;

allocating the multiplexed signal to a subset of sub-carriers; and

transmitting the subset of sub-carriers using Discrete Fourier Transform Spread OFDMA.

2. The method of claim 1 , wherein the subset of sub-carriers is localized within a frequency domain.

3. The method of claim 1 , wherein the subset of sub-carriers is substantially uniformly distributed about a frequency domain.

4. The method of claim 3 , wherein transmitting comprises transmitting using IFDMA.

5. The method of claim 1 , wherein transmitting comprises at least one of performing Inverse Fast Fourier Transform (IFFT) on the subset of sub-carriers and performing a Fast Fourier Transform (FFT) on the subset of sub-carriers.

6. The method of claim 1 , wherein combining into the subset of sub-carriers comprises code multiplexing the plurality of data streams and the pilot signal into the subset of sub-carriers.

7. A receiver coupled to receive a subset of sub-carriers transmitted from a mobile unit using Discrete Fourier Transform Spread OFDMA, comprising:

a filter coupled to extract the subset of sub-carriers, wherein the subset of sub-carriers comprise a multiplex signal that contains a plurality of data streams multiplexed with a pilot signal using a plurality of orthogonal Walsh codes wherein the plurality of data streams comprise a data rate and wherein a pilot gain applied to the pilot signal and a data gain applied to the plurality of data streams are a function of the data rate such that increasing the data rate causes the pilot gain to decrease and the data gain to increase and decreasing the data rate causes the pilot gain to increase and the data gain to decrease;

a Fast Fourier Transform FFT unit coupled to transform the subset of sub-carriers into a frequency domain;

an Inverse Fast Fourier Transform (IFFT) coupled to transform the subset of sub-carriers into a time domain; and

a rake receiver coupled to extract at least one of the plurality of data streams from the multiplexed signal.

8. The receiver of claim 7 , wherein the receiver further comprises a first receiving antenna and a second receiving antenna, wherein the first receiving antenna and the second receiving antenna are coupled to receive the subset of sub-carriers from a first transmitting antenna and a second transmitting antenna on the mobile unit.

9. The receiver of claim 8 , wherein the subset of sub-carriers are spread with a 4-bit pilot Walsh code, wherein the subset of sub-carriers transmitted from the first transmitting antenna include the 4-bit pilot Walsh code in a first set of alternating time blocks, wherein the subset of sub-carriers transmitted from the second transmitting antenna include the 4-bit pilot Walsh code in a second set of alternating time blocks, wherein the first set of alternating time blocks are interleaved with the second set of alternating time blocks.

10. The receiver of claim 8 , wherein the subset of sub-carriers are spread with a first 8-bit pilot Walsh code and a second 8-bit pilot Walsh code, wherein the subset of sub-carriers transmitted from the first transmitting antenna includes the first 8-bit pilot Walsh code, and wherein the subset of sub-carriers transmitted from the second transmitting antenna includes the second 8-bit pilot Walsh code.

11. The receiver of claim 7 , wherein the subset of sub-carriers is localized within a frequency domain.

12. The receiver of claim 7 , wherein the subset of sub-carriers is substantially uniformly distributed about a frequency domain.

13. The receiver of claim 12 , wherein the subset of sub-carriers are transmitted using IFDMA.

14. A method of wireless transmission, comprising:

code multiplexing a pilot signal and a data signal, comprising:

splitting the data signal into a plurality of data streams;

spreading the plurality of data streams and the pilot signal using plurality of orthogonal Walsh codes;

differentially adjusting a data gain applied to the plurality of data streams and a pilot gain applied to the pilot channel as a function of a data rate of the data signal such that increasing the data rate causes the pilot gain to decrease and the data gain to increase and decreasing the data rate causes the pilot gain to increase and the data gain to decrease;

combining the plurality of data streams and the pilot signal into a multiplexed signal containing both the plurality of data streams and the pilot signal

allocating the multiplexed signal to a subset of sub-carriers; and

transmitting the subset of sub-carriers using Discrete Fourier Transform Spread OFDMA.

15. The method of claim 14 , wherein the subset of sub-carriers is transmitted from a mobile unit to a base station over a reverse link.

16. The method of claim 14 , wherein the subset of sub-carriers is localized within a frequency domain.

17. The method of claim 14 , wherein the subset of sub-carriers is substantially uniformly distributed about a frequency domain.

18. The method of claim 17 , wherein transmitting comprises transmitting using IFDMA.

19. A receiver coupled to receive a subset of sub-carriers transmitted from a mobile unit using Discrete Fourier Transform Spread OFDMA, comprising:

a filter coupled to extract the subset of sub-carriers, wherein the subset of sub-carriers comprise a multiplexed signal containing a plurality of data streams multiplexed with a pilot signal using a plurality of orthogonal Walsh codes wherein the plurality of data streams comprise a data rate and wherein a pilot gain applied to the pilot signal and a data gain applied to the plurality of data streams are a function of the data rate such that increasing the data rate causes the pilot gain to decrease and the data gain to increase and decreasing the data rate causes the pilot gain to increase and the data gain to decrease;

a Fast Fourier Transform FFT unit coupled to transform the subset of sub-carriers into a frequency domain;

an Inverse Fast Fourier Transform (IFFT) coupled to transform the subset of sub-carriers into a time domain;

a channel estimator coupled to estimate channels in the time domain; and

a frequency domain equalizer coupled to equalize the subset of sub-carriers in the frequency domain.