Resolving user-specific narrow beam signals using a known sequence in a wireless communications system with a common pilot channel
View Patent ↗A method and apparatus are provided that corrects for differences in reception between a user-specific signal and a common signal. In one embodiment, the invention includes receiving a common pilot signal transmitted on a wide beam at a remote terminal, receiving a user-specific signal transmitted on a directed narrow beam at the remote terminal, demodulating the user-specific signal using the common pilot signal for channel estimation, estimating a phase error in the demodulated user-specific signal using known symbols in the user-specific signal, and correcting for the phase error in the demodulated user-specific signal using the phase error estimates.
1. A method comprising:
receiving a common pilot signal transmitted on a wide beam at a remote terminal;
establishing taps of a multiple tap receiver using the common pilot signal and applying the established taps to receive a user-specific signal transmitted on a directed narrow beam at the remote terminal;
demodulating the user-specific signal using the common pilot signal for channel estimation;
estimating a phase error in the demodulated user-specific signal using known symbols in the user-specific signal to establish replacement taps of the multiple tap receiver; and
correcting for the phase error in the demodulated user-specific signal using the phase error estimates.
2. The method of claim 1 , wherein estimating the phase error comprises estimating the phase error in a multiple tap receiver separately for each tap.
3. The method of claim 1 , wherein estimating the phase error comprises estimating the phase error of a signal combined from multiple taps.
4. The method of claim 1 , wherein estimating the phase error comprises using known symbols in the traffic signal to resolve ambiguities in the phase error of the demodulated user-specific signal.
5. The method of claim 4 , wherein resolving ambiguities comprises resolving ambiguities of the phase error in a multiple tap receiver separately for each tap.
6. The method of claim 4 , wherein resolving ambiguities comprises resolving ambiguities of the phase error in a signal combined from multiple taps.
7. The method of claim 1 , comprising using known symbols in the traffic signal to improve an estimate of the phase error of the demodulated dedicated signal estimated without using known symbols in the dedicated signal.
8. The method of claim 7 , wherein the improvements in the estimates of the phase errors are performed on a tap-by-tap basis.
9. The method of claim 7 , wherein the improvements in the estimates of the phase errors are performed on a signal combined from multiple taps.
10. The method of claim 1 , wherein estimating the phase error comprises using the known symbols of the user-specific signal to establish replacement complex gains for the taps of the multiple tap receiver.
11. A machine-readable medium having stored thereon data representing instructions which, when executed by a machine, cause the machine to perform operations comprising:
receiving a common pilot signal transmitted on a wide beam at a remote terminal;
establishing taps of a multiple tap receiver using the common pilot signal and applying the established taps to receive a user-specific signal transmitted on a directed narrow beam at the remote terminal;
demodulating the user-specific signal using the common pilot signal for channel estimation;
estimating a phase error in the demodulated user-specific signal using known symbols in the user-specific signal to establish replacement taps of the multiple tap receiver; and
correcting for the phase error in the demodulated user-specific signal using the phase error estimates.
12. The medium of claim 11 , wherein the instructions for estimating the phase error comprise instructions which, when executed by the machine, cause the machine to perform further operations comprising estimating the phase error in a multiple tap receiver separately for each tap.
13. The medium of claim 11 , wherein the instructions for estimating the phase error comprise instructions which, when executed by the machine, cause the machine to perform further operations comprising estimating the phase error of a signal combined from multiple taps.
14. The medium of claim 11 , wherein the instructions for estimating the phase error comprise instructions which, when executed by the machine, cause the machine to perform further operations comprising using known symbols in the traffic signal to resolve ambiguities in the phase error of the demodulated user-specific signal.
15. The medium of claim 14 , wherein resolving ambiguities comprises resolving ambiguities of the phase error in a multiple tap receiver separately for each tap.
16. The medium of claim 11 , comprising instructions which, when executed by the machine, cause the machine to perform further operations comprising using known symbols in the traffic signal to improve an estimate of the phase error of the demodulated dedicated signal estimated without using known symbols in the dedicated signal.
17. The medium of claim 16 , wherein the improvements in the estimates of the phase errors are performed on a signal combined from multiple taps.
18. An apparatus comprising:
a multiple tap receiver to receive a common pilot signal transmitted on a wide beam at a remote terminal and a user-specific signal transmitted on a directed narrow beam at the remote terminal, the multiple tap receiver establishing taps using the common pilot signal and applying the established taps to receive the user-specific signal;
a demodulator to demodulate the user-specific signal using the common pilot signal for channel estimation; and
a signal processor to estimate a phase error in the demodulated user-specific signal using known symbols in the user-specific signal to establish replacement complex gains for the multiple tap receiver, and to correct for the phase error in the demodulated user-specific signal using the phase error estimates.
19. The apparatus of claim 18 , wherein the signal processor estimates the phase error by estimating the phase error of a signal combined from multiple taps.
20. The apparatus of claim 18 , wherein the processor estimates the phase error by using known symbols in the traffic signal to resolve ambiguities in the phase error of the demodulated user-specific signal.
21. The apparatus of claim 20 , wherein the processor resolves ambiguities by resolving ambiguities of the phase error in a signal combined from multiple taps.
22. The apparatus of claim 18 , wherein the processor estimates the phase error by using the known symbols of the user-specific signal to establish replacement taps for the multiple tap receiver.