Training assisted joint equalization

• US 10,148,465 B2
• Filed: 12/08/2016
• Issued: 12/04/2018
• Est. Priority Date: 12/08/2015
• Status: Active Grant

• Current Assignee: ZTE Corporation
• Original Assignee: ZTE Corporation
• Inventors: Jia, Zhensheng, Chien, Hung-Chang, Yu, Jianjun
• Primary Examiner(s): Perez, James M
• Application Number:
  US15/530,179
• Publication Number:
  US 20170170993A1
• Time in Patent Office: 726 Days
• Field of Search: 398136-172, 398182-201, 375219-221, 375229-236, 375260-285, 375295-296
• CPC Class Codes: H04L 2025/03815 Transmission of a training request
• CPC Class Codes: H04L 25/03006 Arrangements for removing intersymbol interference
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end

Abstract

Throughput between a transmitter and a receiver is increased by performing a three-stage joint channel optimization in which training sequences are used for calculating a pre-equalization estimate in the first stage, a look up table for pre-distortion in the second stage and a further updating the pre-equalization estimate and the look up table based on a third stage in which the training sequence used for the updating is pre-equalized and pre-distorted using previously calculated values prior to transmitting from the transmitter to the receiver.

Claims

1. A method of optical communication, implemented at a receiver in an optical communication network, comprising:

enabling data communication with a transmitter using a jointly equalized signal using three stages of optimization comprising a pre-equalization stage followed by a pre-distortion stage followed by a joint equalization stage, wherein

the pre-equalization stage includes;

receiving, over an optical channel, an optical signal carrying a first training sequence of symbols, wherein the first training sequence is known a priori to the receiver;

processing the optical signal to estimate an inverse channel response;

communicating the inverse channel response to a transmitter;

the pre-distortion stage includes;

further receiving a second training sequence that is pre-equalized using the inverse channel response;

generating pre-distortion information from the received second training sequence;

transmitting the pre-distortion information to the transmitter; and

the joint equalization stage includes;

receiving a third training sequence that is pre-equalized using the inverse channel response and pre-distorted using the pre-distortion information;

selectively updating, based on an improvement of bit error level, the inverse channel response and the pre-distortion information from the received third training sequence; and

communicating, when updated, the inverse channel response and the pre-distortion information to the transmitter.

2. The method of claim 1, wherein the receiving and the processing operations in the pre-equalization stage are performed iteratively.

3. The method of claim 1, wherein the further receiving and the generating operations in the pre-distortion stage are performed iteratively.

4. The method of claim 1, wherein the receiving the third training sequence and selectively updating operations are performed iteratively.

5. The method of claim 1, wherein a same training sequence is used as the first training sequence, the second training sequence and the third training sequence.

6. An optical communication receiver apparatus, comprising:

one or more memories holding data and instructions;

a processor that reads the instructions and implements a receiver-side method of enabling data communication with a transmitter using a jointly equalized signal using three stages of optimization comprising a pre-equalization stage followed by a pre-distortion stage followed by a joint equalization stage;

the instructions comprising;

instructions for executing the pre-equalization stage by;

receiving, over an optical channel, an optical signal carrying a first training sequence of symbols, wherein the first training sequence is known a priori to the receiver;

processing the optical signal to estimate an inverse channel response;

communicating the inverse channel response to a transmitter;

instructions for executing the pre-distortion stage by;

further receiving a second training sequence that is pre-equalized using the inverse channel response;

generating pre-distortion information from the received second training sequence;

transmitting the pre-distortion information to the transmitter; and

instructions for executing the joint equalization stage by;

receiving a third training sequence that is pre-equalized using the inverse channel response and pre-distorted using the pre-distortion information;

selectively updating, based on an improvement of bit error level, the inverse channel response and the pre-distortion information from the received third training sequence; and

communicating, when updated, the inverse channel response and the pre-distortion information to the transmitter.

7. The apparatus of claim 6, wherein the instructions for implementing the pre-equalization stage include instructions for iteratively performing the receiving and the processing operations.

8. The apparatus of claim 6, wherein the instructions for implementing the pre-distortion stage include instructions for iteratively performing the receiving the training sequence and the generating operations.

9. The apparatus of claim 6, wherein the instructions for implementing the joint equalization stage include instructions for iteratively performing the receiving the third training sequence and selectively updating operations.

10. The apparatus of claim 6, wherein a same training sequence is used as the first training sequence, the second training sequence and the third training sequence.

11. A method of optical communication, implemented at a transmitter in an optical communication network, comprising:

enabling data communication with a receiver using a jointly equalized signal using three stages of optimization comprising a pre-equalization stage followed by a pre-distortion stage followed by a joint equalization stage, wherein

the pre-equalization stage includes;

transmitting, over an optical channel, an optical signal carrying a first training sequence of symbols;

receiving an estimate of an inverse channel response;

storing the estimate of the inverse channel response at the transmitter;

the pre-distortion stage includes;

pre-equalizing and transmitting a second training sequence using the estimate of the inverse channel response;

receiving pre-distortion information generated based on the second training sequence; and

storing the pre-distortion information at the transmitter; and

the joint equalization stage includes;

jointly performing pre-distortion and pre-equalization of a third training sequence using the estimate of the inverse channel response and the pre-distortion information to generate a pre-distorted and pre-equalized third training sequence;

transmitting the pre-distorted and pre-equalized third training sequence over the optical channel; and

receiving, based on the pre-distorted and pre-equalized third training sequence, updating information for updating the estimate of the inverse channel response and the pre-distortion information stored at the transmitter.

12. The method of claim 11, wherein the transmitting, the receiving and the storing operations in the pre-equalization stage are performed iteratively.

13. The method of claim 11, wherein the further pre-equalizing, the transmitting, the storing and the receiving operations in the pre-distortion stage are performed iteratively.

14. The method of claim 11, wherein the jointly performing pre-distortion and pre-equalization and the transmitting and the receiving operations of the joint equalization stage are performed iteratively.

15. The method of claim 11, wherein a same training sequence is used as the first training sequence, the second training sequence and the third training sequence.

16. An optical communication transmission apparatus, comprising:

one or more memories holding data and instructions;

a processor that reads the instructions and implements a method of enabling data communication using a jointly equalized signal using three stages of optimization comprising a pre-equalization stage followed by a pre-distortion stage followed by a joint equalization stage;

the instructions comprising;

instructions for implementing the pre-equalization stage includes;

transmitting, over an optical channel, an optical signal carrying a first training sequence of symbols;

receiving an estimate of an inverse channel response;

storing the estimate of the inverse channel response at the transmitter;

instructions for implementing the pre-distortion stage by;

pre-equalizing and transmitting a second training sequence using the estimate of the inverse channel response;

receiving pre-distortion information generated based on the second training sequence; and

storing the pre-distortion information at the transmitter; and

instructions for implementing the joint equalization stage by;

jointly performing pre-distortion and pre-equalization of a third training sequence using the estimate of the inverse channel response and the pre-distortion information to generate a pre-distorted and pre-equalized third training sequence;

transmitting the pre-distorted and pre-equalized third training sequence over the optical channel; and

receiving, based on the pre-distorted and pre-equalized third training sequence, updating information for updating the estimate of the inverse channel response and the pre-distortion information stored at the transmitter.

17. The apparatus of claim 16, wherein the instructions for implementing the pre-equalization stage include instructions for iteratively performing the transmitting the receiving and the storing operations of the pre-equalization stage.

18. The apparatus of claim 16, wherein the instructions for implementing the pre-distortion stage include instructions for iteratively performing the pre-equalizing and transmitting, the receiving and the storing operations of the pre-distortion stage.

19. The apparatus of claim 16, wherein the instructions for implementing the joint equalization stage include instructions for iteratively performing the joint pre-distortion and pre-equalization, the transmitting and the receiving operations of the joint equalization stage.

20. The apparatus of claim 16, wherein a same training sequence is used as the first training sequence, the second training sequence and the third training sequence.

21. An optical communication system comprising a transmission apparatus and a receiver apparatus communicatively coupled to each other through an optical communication channel, wherein the transmission apparatus implements a method comprising:

enabling data communication with the receiver apparatus using a jointly equalized signal using three stages of optimization comprising a pre-equalization stage followed by a pre-distortion stage followed by a joint equalization stage, wherein

the pre-equalization stage includes;

transmitting, over an optical channel, an optical signal carrying a first training sequence of symbols;

receiving an estimate of an inverse channel response;

storing the estimate of the inverse channel response at the transmitter;

the pre-distortion stage includes;

pre-equalizing and transmitting a second training sequence using the estimate of the inverse channel response;

receiving pre-distortion information generated based on the second training sequence; and

storing the pre-distortion information at the transmitter; and

the joint equalization stage includes;

jointly performing pre-distortion and pre-equalization of a third training sequence using the estimate of the inverse channel response and the pre-distortion information to generate a pre-distorted and pre-equalized third training sequence;

transmitting the pre-distorted and pre-equalized third training sequence over the optical channel; and

receiving, based on the pre-distorted and pre-equalized third training sequence, updating information for updating the estimate of the inverse channel response and the pre-distortion information stored at the transmitter; and

the receiver apparatus implements a method comprising;

enabling data communication with the transmitter apparatus using a jointly equalized signal using three stages of optimization comprising a pre-equalization stage followed by a pre-distortion stage followed by a joint equalization stage, wherein

the pre-equalization stage includes;

receiving, over an optical channel, an optical signal carrying a first training sequence of symbols, wherein the first training sequence is known a priori to the receiver;

processing the optical signal to estimate an inverse channel response;

communicating the inverse channel response to the transmitter apparatus;

the pre-distortion stage includes;

further receiving a second training sequence that is pre-equalized using the inverse channel response;

generating pre-distortion information from the received second training sequence;

transmitting the pre-distortion information to the transmitter; and

the joint equalization stage includes;

receiving a third training sequence that is pre-equalized using the inverse channel response and pre-distorted using the pre-distortion information;

selectively updating, based on an improvement of bit error level, the inverse channel response and the pre-distortion information from the received third training sequence; and

communicating, when updated, the inverse channel response and the pre-distortion information to the transmitter apparatus.

22. The optical communication system of claim 21, wherein the transmitting, the receiving and the storing operations implemented at the transmitter apparatus in the pre-equalization stage are performed iteratively.

23. The optical communication system of claim 21, wherein the further pre-equalizing, the transmitting, the storing and the receiving operations implemented at the transmitter apparatus in the pre-distortion stage are performed iteratively.

24. The optical communication system of claim 21, wherein the jointly performing pre-distortion and pre-equalization and the transmitting and the receiving operations implemented at the transmitter in the joint equalization stage are performed iteratively.

25. The optical communication system of claim 21, wherein a same training sequence is used as the first training sequence, the second training sequence and the third training sequence for the transmitter apparatus.

26. The optical communication system of claim 21, wherein the receiving and the processing operations implemented at the receiver apparatus in the pre-equalization stage are performed iteratively.

27. The optical communication system of claim 21, wherein the further receiving and the generating operations implemented at the receiver apparatus in the pre-distortion stage are performed iteratively.

28. The optical communication system of claim 21, wherein the receiving the third training sequence and selectively updating operations implemented at the receiver apparatus in the joint equalization stage are performed iteratively.

29. The optical communication system of claim 21, wherein a same training sequence is used as the first training sequence, the second training sequence and the third training sequence for the receiver apparatus.