System and method for training signals for full-duplex communications systems

• US 9,748,990 B2
• Filed: 02/09/2015
• Issued: 08/29/2017
• Est. Priority Date: 02/09/2015
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: Wu, Huan, Hum, Eddy Shi-Ning
• Primary Examiner(s): KHIRODHAR, MAHARISHI V
• Application Number:
  US14/617,598
• Publication Number:
  US 20160233903A1
• Time in Patent Office: 932 Days
• CPC Class Codes: H04B 1/12 Neutralising, balancing, or compensation arrangements
• CPC Class Codes: H04B 15/00 Suppression or limitation of noise or interference by means associated with receiver H04B1/10
• CPC Class Codes: H04J 13/0062 Zadoff-Chu
• CPC Class Codes: H04L 25/0244 with inversion
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 27/26134 Pilot insertion in the transmitter chain, e.g. pilot overlapping with data, insertion in time or frequency domain
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/1461 Suppression of signals in the return path, i.e. bidirectional control circuits
• CPC Class Codes: H04L 5/16 Half-duplex systems; Simplex/duplex switching; Transmission of break signals non-automatically inverting the direction of transmission
• CPC Class Codes: H04L 69/14 Multichannel or multilink protocols
• CPC Class Codes: H04L 69/22 Parsing or analysis of headers

Abstract

A method includes transmitting a training signal derived from a sequence, the training signal facilitates an estimation of a channel impulse response (CIR) for a communications channel between a transmit antenna of the device and a receive antenna of the device, estimating the CIR for the communications channel, and receiving signals corresponding to a first transmission at the receive antenna. The method also includes cancelling self-interference present in the received signals in accordance with the estimated CIR, the self-interference arising from a second transmission made by the transmit antenna of the device, thereby producing an interference canceled received signal, and processing the interference canceled received signal.

Claims

1. A method for operating a device configured to operate in a full-duplex mode, the method comprising:

transmitting, by the device, a training signal derived from a sequence, the training signal configured to facilitate an estimation of a channel impulse response (CIR) for a communications channel between a transmit antenna of the device and a receive antenna of the device;

estimating, by the device, the CIR for the communications channel;

receiving, by the device, signals corresponding to a first transmission at the receive antenna;

cancelling, by the device, self-interference present in the received signals in accordance with the estimated CIR, the self-interference arising from a second transmission made by the transmit antenna of the device, thereby producing an interference canceled received signal; and

processing, by the device, the interference canceled received signal,

wherein transmitting the training signal comprises generating a plurality of training sequences from a set of sequences in accordance with a communications system requirement, mapping a first training sequence to a transmit antenna, multiplexing the mapped first training sequence with data symbols to produce a transmission stream, and transmitting the transmission stream as the training signal.

2. The method of claim 1, wherein the sequence has a correlation matrix that is a scaled identity matrix.

3. The method of claim 1, wherein the plurality of training sequences comprises a zero-correlation-zone (ZCZ) sequence.

4. The method of claim 1, wherein the communications system requirement comprises at least one of:

a length of a training sequence is equal to a desired symbol length N before a cyclic prefix is added, wherein N is an integer value;

a size of e the plurality of training sequences is at least equal to a number of transmit antennas of the device N_b; and

a sequence zone length of the plurality of training sequences is at least equal to a channel delay spread L_b which dictates a minimum ZCZ zone length for auto-correlations and cross-correlations of the plurality of training sequences.

5. The method of claim 1, wherein the plurality of training sequences are derived from Zadoff-Chu sequences.

6. The method of claim 1, wherein the training signal is transmitted while the device is operating in a half-duplex mode.

7. The method of claim 1, wherein the training signal is transmitted in a special subframe comprising a downlink portion, a training portion, and an uplink portion.

8. The method of claim 7, wherein the training signal is transmitted in the training portion of the special subframe.

9. The method of claim 7, wherein the training signal is transmitted in the downlink portion and the training portion of the special subframe.

10. The method of claim 1, wherein each sequence in the set of sequences has a correlation matrix that is a scaled identity matrix.

11. The method of claim 1, wherein transmitting the transmission stream further comprises filtering the transmission stream.

12. The method of claim 1, further comprising appending a cyclic prefix to the mapped first training sequence prior to multiplexing.

13. A device configured for full-duplex operation comprises:

a transmitter configured to transmit a training signal derived from a sequence, the training signal configured to facilitate an estimation of a channel impulse response (CIR) for a communications channel between a transmit antenna of the device and a receive antenna of the device;

a processor operatively coupled to the transmitter, the processor configured to estimate the CIR for the communications channel, cancel a self-interference present in received signals in accordance with the estimated CIR, the received signals corresponding to a first transmission at the receive antenna, and the self-interference arising from a second transmission made by the transmit antenna of the device, thereby producing an interference canceled received signal, and process the interference canceled received signal; and

a receiver operatively coupled to the processor, the receiver configured to receive the received signals; and

wherein transmit the training signal comprises generating a plurality of training sequences from a set of sequences in accordance with a communications system requirement, mapping a first training sequence to the transmit antenna, multiplexing the mapped first training sequence with data symbols to produce a transmission stream, and transmitting the transmission stream as the training signal.

14. The device of claim 13, wherein the plurality of training sequences comprises a zero-correlation-zone (ZCZ) sequence.

15. The device of claim 13, wherein the transmitter is configured to transmit the training signal in a half-duplex mode.

16. The device of claim 13, wherein the transmitter is configured to transmit the training signal in a training portion of a special subframe.

17. The device of claim 16, wherein the transmitter is configured to transmit the training signal in a downlink portion of the special subframe.

18. The device of claim 13, wherein the device comprises an evolved NodeB.

19. A method, comprising:

transmitting, a zero-correlation-zone (ZCZ) sequence selected from a set of ZCZ sequences over a transmit antenna of a device, the device configured to operate in a full-duplex mode;

receiving the ZCZ sequence over a receive antenna of the device;

estimating a channel impulse response (CIR) for a communications channel between the transmit antenna and the receive antenna according to the ZCZ sequence;

transmitting a first signal over the transmit antenna of the device;

receiving a second signal over the receive antenna of the device, the first signal and the second signal being full-duplexed signals and the second signal comprises a self-interference component attributable to the first signal; and

cancelling, by the device, the self-interference component from the second signal in accordance with the estimated CIR.

20. The method of claim 19, wherein the set of ZCZ sequences has a correlation matrix that is a scaled identity matrix.

21. The method of claim 19, wherein the set of ZCZ sequences is derived from a Zadoff-Chu sequence.

22. The method of claim 19, wherein each ZCZ sequence in the set of ZCZ sequences has a length that is equal to a pre-defined symbol length without a cyclic prefix added.

23. The method of claim 19, wherein the transmit antenna of the device comprises multiple antenna elements, wherein a number of ZCZ sequences in the set of ZCZ sequences is equal to or greater than a number of the multiple antenna elements in the transmit antenna of the device.

24. The method of claim 19, wherein the set of ZCZ sequences has a ZCZ zone length that is equal to or greater than a predefined threshold for auto-correlations and cross-correlations of the set of ZCZ sequences.

25. The method of claim 19, wherein the ZCZ sequence is transmitted when the device is operating in a half-duplex mode.

26. The method of claim 19, further comprising mapping the ZCZ sequence to the transmit antenna of the device before transmitting the ZCZ sequence.

27. The method of claim 19, wherein transmitting the ZCZ sequence comprises:

multiplexing the ZCZ sequence with data symbols to produce a transmission stream; and

transmitting the transmission stream over the transmit antenna.