초록 ▼

In one embodiment, the invention is directed toward frequency tracking techniques using control symbols that include both pilot and non-pilot symbols. For example, both the pilot and non-pilot symbols can be used in estimating frequency error of a received signal. The contribution of non-pilot symb

In one embodiment, the invention is directed toward frequency tracking techniques using control symbols that include both pilot and non-pilot symbols. For example, both the pilot and non-pilot symbols can be used in estimating frequency error of a received signal. The contribution of non-pilot symbols to the estimation can be weighted according to a confidence level associated with each non-pilot symbol. In some cases, soft decisions are generated for the non-pilot symbols and then used with the pilot symbols for frequency tracking. In this manner, the frequency tracking loop can be improved.

대표청구항 ▼

The invention claimed is: 1. A method comprising: obtaining control symbols from a first wireless signal, the control symbols including pilot symbols and non-pilot symbols; generating soft decisions for the non-pilot symbols; and using both the pilot symbols and the soft decisions for frequency tra

The invention claimed is: 1. A method comprising: obtaining control symbols from a first wireless signal, the control symbols including pilot symbols and non-pilot symbols; generating soft decisions for the non-pilot symbols; and using both the pilot symbols and the soft decisions for frequency tracking of the first wireless signal. 2. The method of claim 1, wherein generating soft decisions for the non pilot symbols comprises weighting each non-pilot symbol. 3. The method of claim 2, wherein the soft decisions comprise non-pilot symbols multiplied by a weight factor. 4. The method of claim 1, wherein using the pilot symbols and the soft decisions for frequency tracking includes calculating a cross-product to generate a residual frequency error estimate. 5. The method of claim 4, wherein calculating the cross-product comprises cross-multiplying one of the pilot symbols with a complex conjugate of one of the soft decisions. 6. The method of claim 4, wherein calculating the cross-product comprises cross-multiplying one of the soft decisions with a complex conjugate of one of the pilot symbols. 7. The method of claim 4, wherein calculating the cross-product comprises cross-multiplying a first set of the pilot symbols and soft decisions with a complex conjugate of a second set of the pilot symbols and soft decisions. 8. The method of claim 7, wherein the first set and the second set include at least one common symbol. 9. The method of claim 8, wherein the common symbol is a first symbol in the first set and a last symbol in the second set. 10. The method of claim 1, further comprising adjusting frequency of the first wireless signal in response to the frequency tracking. 11. The method of claim 1, wherein the soft decisions include a decision as to whether the symbol is a 1 or a-1 and a confidence level of the decision as to whether the symbol is a 1 or a-1. 12. The method of claim 1, wherein generating the soft decision includes applying a hyperbolic tangent function to calculate the soft decision. 13. The method of claim 1, wherein generating the soft decision includes applying an approximation of a hyperbolic tangent function to calculate the soft decision. 14. The method of claim 1, wherein generating the soft decision includes using a sign function to calculate a decision as to whether the non-pilot symbol is a 1 or a-1. 15. The method of claim 1, wherein the first wireless signal is a spread spectrum CDMA signal. 16. The method of claim 2, wherein weighing each non-pilot symbol includes weighing each non-pilot symbol according to strength of the first wireless signal. 17. The method of claim 2, wherein weighing each non-pilot symbol includes weighing each non-pilot symbol according to a signal-to-noise-plus interference ratio associated with the first wireless signal. 18. The method of claim 4, further comprising calculating cross-products to calculate residual frequency error estimates and accumulating the cross-products to calculate an estimated frequency error of the first wireless signal. 19. The method of claim 1, wherein the non-pilot symbols include transport format combination indicators, transmit power control indicators and feedback indicators. 20. A method comprising: obtaining control symbols from a first wireless signal, the control symbols including pilot symbols and non-pilot symbols; assigning a weight factor to each non-pilot symbol; and using the pilot symbols and weighted non-pilot symbols for frequency tracking of the first wireless signal. 21. A computer-readable medium carrying program code that when executed: obtains control symbols from a first wireless signal, the control symbols including pilot symbols and non-pilot symbols; generates soft decisions for the non-pilot symbols; and uses the pilot symbols and the soft decisions for frequency tracking of the first wireless signal. 22. An apparatus comprising: a rotator that adjusts signal frequency of a signal; a soft decision generator that determines soft decisions for non-pilot symbols; and a feedback loop to the rotator and the soft decision generator that provides an estimate of a frequency error associated with the signal, wherein the feedback loop generates the estimate of the frequency error using pilot symbols and soft decisions. 23. The apparatus of claim 22, further comprising: a transmitter/receiver that receives and conditions the signal before sending the signal to the rotator; a demodulator that demodulates the signal after the rotator has adjusted signal frequency of the signal; a symbol generator that obtains the pilot and non-pilot symbols; and a digital signal processor that processes the pilot and non-pilot symbols. 24. The apparatus of claim 22, wherein the feedback loop includes a frequency discriminator and an accumulator, wherein the frequency discriminator calculates residual frequency error estimates using the pilot and non-pilot symbols and sends the residual frequency error estimates to the accumulator to generate the estimate of the frequency error. 25. The apparatus of claim 24, wherein the soft decision generator includes a hyperbolic tangent unit that generates the soft decisions. 26. The apparatus of claim 24, wherein the frequency discriminator includes a cross-product generator to estimate residual frequency errors. 27. The apparatus of claim 22, wherein the apparatus forms part of a RAKE receiver, the apparatus further comprising: a number of rotators that adjust signal frequency of a number of signals tracked by a number of fingers; and a number of feedback loops to the number of rotators that provide estimates of frequency errors associated with the signals, wherein the feedback loops generate the estimates of the frequency errors using pilot and non-pilot symbols. 28. An apparatus comprising: an antenna; a transmitter/receiver coupled to the antenna that receives a signal and conditions the signal; a rotator coupled to the transmitter/receiver that adjusts frequency of the signal; a demodulator coupled to the rotator that demodulates the signal; a symbol generator coupled to the demodulator that obtains control symbols from the demodulated signal, the control symbols including pilot and non pilot symbols; a soft decision generator coupled to the symbol generator that generates soft decisions for the non-pilot symbols; a frequency discriminator coupled to the soft decision generator that calculates residual frequency error estimates using the pilot symbols and the soft decisions; and an accumulator coupled to the frequency discriminator and the rotator that accumulates an error estimate associated with the signal, wherein the rotator adjusts frequency of the signal based on the error estimate associated with the signal. 29. The apparatus of claim 28, wherein the apparatus forms part of a RAKE receiver, the apparatus further comprising: a number of fingers that track a number of signals, wherein each finger includes a rotator, a demodulator coupled to the rotator, a symbol generator coupled to the demodulator, a soft decision generator coupled to the symbols generator, a frequency discriminator coupled to the soft decision generator, and an accumulator coupled to the frequency discriminator and the rotator.