Technique for radio channel estimation

Patent metadata

Field	Value
Publication number	US-10587435-B2
Application number	US-201815764623-A
Country	US
Kind code	B2
Filing date	Jan 25, 2018
Priority date	Jan 25, 2018
Publication date	Mar 10, 2020
Grant date	Mar 10, 2020

Abstract

A technique for determining channel coefficients for a first array of antennas coupled through respective first phase shifters to a first radio chain and a second array of antennas coupled through respective second phase shifters to a second radio chain is described. As to a method aspect of the technique, pairs of first and second phase vectors are applied to the first and second phase shifters, respectively. Each of the pairs defines complementary directional gains at the first and second arrays for receiving reference signals. A channel estimation is performed in each of the first and second radio chains for each of the pairs based on the received reference signals. Based on the channel estimations for each of the pairs, at least one channel coefficient for the antennas in each of the first and second arrays is determined.

First claim

The invention claimed is:

1. A method of determining channel coefficients for a first array of antennas coupled through respective first phase shifters to a first radio chain and a second array of antennas coupled through respective second phase shifters to a second radio chain, the method comprising the steps of:
applying pairs of first and second phase vectors to the first and second phase shifters, respectively, each of the pairs defining complementary directional gains at the first and second arrays for receiving reference signals;
performing or initiating a channel estimation in each of the first and second radio chains for each of the pairs based on the received reference signals; and
determining, based on the channel estimations for each of the pairs, at least one channel coefficient for the antennas in each of the first and second arrays.

2. A device for determining channel coefficients for a first array of antennas coupled through respective first phase shifters to a first radio chain and a second array of antennas coupled through respective second phase shifters to a second radio chain, the device comprising at least one processor and a memory, said memory comprising instructions executable by said at least one processor, whereby the device is operative to:
apply pairs of first and second phase vectors to the first and second phase shifters, respectively, each of the pairs defining complementary directional gains at the first and second arrays for receiving reference signals;
perform or initiate a channel estimation in each of the first and second radio chains for each of the pairs based on the received reference signals; and
determine, based on the channel estimations for each of the pairs, at least one channel coefficient for the antennas in each of the first and second arrays.

3. The device of claim 2 , wherein the reference signals are received from a multi-antenna station, the device further operative to:
transmit a control message to the multi-antenna station, the control message being indicative of a precoding matrix depending on the determined channel coefficients.

4. The device of claim 2 , wherein the at least one channel coefficient determined for the antennas in each of the first and second arrays comprises at least one combination of channel coefficients of each of the antennas in the corresponding array.

5. The device of claim 2 , wherein the channel coefficients are determined for each of the antennas in each of the first and second antenna arrays or for each but one of the antennas in each of the first and second antenna arrays.

6. The device of claim 2 , wherein the device is further operative to:
perform or initiate at least one of a beamforming transmission and a beamforming reception based on the determined channel coefficients.

7. The device of claim 6 , wherein the phases are controlled for those phase shifters coupled with the antennas for which the channel coefficients are determined.

8. The device of claim 6 , wherein a complex weight is applied in each of the first and second radio chains, and wherein, for each of the phase shifters, a combination of the phase at the phase shifter and the complex weight applied in the radio chain coupled to the phase shifter depends on at least one of the channel coefficients determined for the antennas and the channel estimates in the radio chain.

9. The device of claim 6 , wherein, for each of the antennas, the sum of a phase of the phase shifter coupled to the antenna and a phase applied in the radio chain coupled to the phase shifter matches a phase of the channel coefficient determined for the antenna.

10. The device of claim 2 , wherein the device is further operative to:
control the directional gain by controlling phases of the first and second phase shifters based on the determined channel coefficients.

11. The device of claim 2 , wherein baseband signals of the first and second radio chains are combined for decoding.

12. The device of claim 2 , wherein the phase shifters are implemented in an analog domain, and wherein the radio chains are implemented in a digital domain.

13. The device of claim 2 , wherein the complementary directional gains at the first and second arrays defined by each of the pairs correspond to a widebeam of the first and second arrays.

14. The device of claim 2 , wherein each of the pairs of the first and second phase vectors includes a pair of complementary sequences.

15. The device of claim 2 , wherein different pairs of first and second phase vectors are applied in different transmission time intervals, TTI.

16. The device of claim 2 , wherein, for each of the first and second antenna arrays, the respective phase vectors applied at the respective antenna array are linearly independent.

17. The device of claim 16 , wherein, for each of the first and second antenna arrays, determining the channel coefficients of the antennas of the respective antenna array includes multiplying an inverse matrix of the respective phase vectors to results of the channel estimates in the respective radio chain.

18. The device of claim 2 , wherein the device is further operable to:
receive or initiate to receive both control information and at least one of the reference signals in a TTI during which at least one of the pairs of first and second phase vectors is applied.

19. A non-transitory computer readable medium comprising instructions executable by a processor to determine channel coefficients for a first array of antennas coupled through respective first phase shifters to a first radio chain and a second array of antennas coupled through respective second phase shifters to a second radio chain, whereby the processor is operable to:
apply pairs of first and second phase vectors to the first and second phase shifters, respectively, each of the pairs defining complementary directional gains at the first and second arrays for receiving reference signals;
perform or initiating a channel estimation in each of the first and second radio chains for each of the pairs based on the received reference signals; and
determine, based on the channel estimations for each of the pairs, at least one channel coefficient for the antennas in each of the first and second arrays.

20. A user equipment, UE, configured to communicate with a base station, the UE comprising a radio interface and processing circuitry, wherein in order to determine channel coefficients for a first array of antennas coupled through respective first phase shifters to a first radio chain and a second array of antennas coupled through respective second phase shifters to a second radio chain, the processing circuitry is configured to cause the UE to:
apply pairs of first and second phase vectors to the first and second phase shifters, respectively, each of the pairs defining complementary directional gains at the first and second arrays for receiving reference signals;
perform or initiate a channel estimation in each of the first and second radio chains for each of the pairs based on the received reference signals; and
determine, based on the channel estimations for each of the pairs, at least one channel coefficient for the antennas in each of the first and second arrays.

21. A communication system including a host computer comprising:
processing circuitry configured to provide user data; and a communication interface configured to forward user data to a cellular network for transmission to a user equipment, UE, wherein the UE comprises a radio interfac

Assignees

• Ericsson Telefon Ab L M

Inventors

• Sun Wanlu
• Sorrentino Stefano

Classifications

• H04B7/0868 Primary

  Hybrid systems, i.e. switching and combining · CPC title

• H04L25/0204

  of multiple channels · CPC title

• H04B7/063

  Parameters other than those covered in groups H04B7/0623 - H04B7/0634, e.g. channel matrix rank or transmit mode selection · CPC title

• H04B7/0413

  MIMO systems · CPC title

• H04W72/0446

  Resources in time domain, e.g. slots or frames · CPC title