Signaling techniques in the presence of phase noise and frequency offset
Systems and methods are provided for enabling reliable signaling in the presence of strong phase noise and frequency offset. To this end, a method is provided comprising receiving, at a receiver, a communication signal, including data, from a transmitter via a communication channel, and jointly tracking and jointly correcting phase noise errors and frequency errors in the communication signal with a joint detector using an iterative feedback correction process between an output decoder of the receiver and the joint detector.
1. A method comprising:
receiving, at a receiver, a communication signal, including data, from a transmitter via a communication channel; and
jointly tracking and jointly correcting phase noise errors and frequency errors in the communication signal with a joint detector using an iterative feedback correction process between an output decoder of the receiver and the joint detector.
2. The method of claim 1 , wherein the joint tracking and joint correcting of both phase noise errors and frequency errors in the communication signal are carried out in the joint detector using pilots, interspersed between data in the communication signal.
3. The method of claim 2 , wherein the iterative feedback correction process includes a branch metric update step for updating a branch metric in the joint detector.
4. The method of claim 2 , wherein the iterative feedback correction process includes a symbol a posteriori probabilities (APP) calculation and bit log likelihood ratio (LLR) calculation step.
5. The method of claim 4 , wherein the iterative feedback correction process further includes a forward recursion step and a backward recursion step.
6. The method of claim 5 , wherein the branch metric update step and the forward recursion step are performed concurrently.
7. The method of claim 5 , wherein the backward recursion step and the symbol APP calculation and bit LLR calculation step are performed concurrently.
8. The method of claim 5 , wherein the backward recursion step and the symbol APP calculation and bit LLR calculation step are performed concurrently, after the branch metric update step and the forward recursion step are performed concurrently.
9. The method of claim 1 , further comprising outputting a final estimate of information bits in the data in the communication signal from the output decoder of the receiver after a predetermined maximum number of iterative steps of the iterative feedback correction process has been reached.
10. A receiver in a communication system comprising:
a filter of the receiver configured to receive a communication signal, including data, from a transmitter via a communication channel; and
a joint detector including an output and a feedback input and
an iterative feedback loop comprised of an output decoder coupled between the output of the joint detector and the feedback input of the joint detector,
wherein the joint detector is configured to jointly track and jointly correct phase noise errors and frequency errors in the communication signal using an iterative feedback correction process via the iterative feedback loop.
11. The receiver of claim 10 , wherein the joint detector configured to jointly track and jointly correct both phase noise errors and frequency errors in the communication signal uses pilots, interspersed between data in the communication signal.
12. The receiver of claim 11 , wherein the iterative feedback correction process includes a branch metric update step for updating a branch metric in the joint detector.
13. The receiver of claim 11 , wherein the iterative feedback correction process includes a symbol a posteriori probabilities (APP) calculation and bit log likelihood ratio (LLR) calculation step.
14. The receiver of claim 13 , wherein the iterative feedback correction process further includes a forward recursion step and a backward recursion step.
15. The receiver of claim 14 , wherein the branch metric update step and the forward recursion step are performed concurrently.
16. The receiver of claim 14 , wherein the backward recursion step and the symbol APP calculation and bit LLR calculation step are performed concurrently.
17. The receiver of claim 14 , wherein the backward recursion step and the symbol APP calculation and bit LLR calculation step are performed concurrently, after the branch metric update step and the forward recursion step are performed concurrently.
18. The receiver of claim 10 , wherein the output decoder is configured to output a final estimate of information bits in the data in the communication signal after a predetermined maximum number of iterative steps of the iterative feedback correction process has been reached.
19. The receiver of claim 10 , wherein the communication signal received from the transmitter via the communication channel is down converted by a down converter in the receiver prior to being applied to the filter of the receiver.