Method for calibrating data sent by coordinated APs and base station

• US 9,537,625 B2
• Filed: 06/27/2013
• Issued: 01/03/2017
• Est. Priority Date: 08/13/2012
• Status: Active Grant

• Current Assignee: Guangdong OPPO Mobile Telecommunications Corporation Limited
• Original Assignee: ZTE Corporation
• Inventors: Zhao, Yajun, Mo, Linmei, Xu, Hanqing, Li, Yujie, Sun, Baoyu, Huang, Chen
• Primary Examiner(s): Phillips, Hassan
• Assistant Examiner(s): Wei, Siren
• Application Number:
  US14/414,510
• Publication Number:
  US 20150172014A1
• Time in Patent Office: 1,286 Days
• US Class Current: 1/1
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/022 of frequency response
• CPC Class Codes: H04L 5/0005 Time-frequency
• CPC Class Codes: H04L 5/0035 Resource allocation in a cooperative multipoint environment
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

A method and a base station for calibrating data transmitted by coordinated APs are disclosed. The method includes: a base station obtaining an uplink channel frequency-domain response and a downlink channel frequency-domain response between a first AP and a second AP which participate in coordination; the base station dividing the uplink channel frequency-domain response by the downlink channel frequency-domain response to obtain an uplink and downlink channel response difference between the first AP and the second AP; and the base station calibrating the data transmitted by the first AP and the second AP in coordination according to the uplink and downlink channel response difference. The method and base station in the embodiments of the present document are applied to calibrate the data transmitted by coordinated APs.

Claims

1. A method for calibrating data transmitted by coordinated Access Points (APs), comprising:

a base station obtaining an uplink channel frequency-domain response and a downlink channel frequency-domain response between a first AP and a second AP which participate in coordination;

the base station dividing the uplink channel frequency-domain response by the downlink channel frequency-domain response to obtain an uplink-downlink channel response difference between the first AP and the second AP; and

the base station calibrating the data transmitted by the first AP and the second AP in coordination according to the uplink-downlink channel response difference;

wherein the step of the base station obtaining the uplink channel frequency-domain response and the downlink channel frequency-domain response between the first AP and the second AP which participate in coordination comprises;

the base station obtaining a channel frequency-domain response calculated by the second AP at a time t1 according to a calibration sequence received from the first AP, and using the channel frequency-domain response as the downlink channel frequency-domain response between the first AP and the second AP;

the base station obtaining a channel frequency-domain response calculated by the first AP at a time t2 according to a calibration sequence received from the second AP, and using the channel frequency-domain response as the uplink channel frequency-domain response between the first AP and the second AP;

when the first AP and the second AP have not performed self-calibration of their own set of antennas, if the obtained downlink channel frequency-domain response is calculated by the second AP at the time t1 according to the calibration sequence transmitted by the first AP via an antenna Ant(j) and received by the second AP via an antenna Ant(i), the base station obtaining the uplink channel frequency-domain response calculated by the first AP at the time t2 according to the calibration sequence transmitted by the second AP via the antenna Ant(i) and received by the first AP via the antenna Ant(j), and

when the first AP and the second AP have performed self-calibration of their own set of antennas, if the obtained downlink channel frequency-domain response is calculated by the second AP at the time t1 according to the calibration sequence transmitted by the first AP via an antenna Ant(j) and received by the second AP via an antenna Ant(i), the base station obtaining the uplink channel frequency-domain response calculated by the first AP at the time t2 according to the calibration sequence transmitted by the second AP via an antenna Ant(j′

) and received by the first AP via an antenna Ant(i′

);

wherein iε

[0,N−

1], i′

ε

[0,N−

1], jε

[0,N−

1], j′

ε

[0,N−

1], the time t1 is different from the time t2, and N is a number of antennas of the coordinated AP.

2. The method according to claim 1, wherein, the step of the base station dividing the uplink channel frequency-domain response by the downlink channel frequency-domain response to obtain the uplink-downlink channel response difference between the first AP and the second AP comprises:

the base station obtaining multiple uplink channel frequency-domain responses calculated at different times and transmitted by the first AP, and taking a statistic value of the multiple uplink channel frequency-domain responses calculated at different times to participate in calculation of the uplink-downlink channel response difference between the first AP and the second AP; and

the base station obtaining multiple downlink channel frequency-domain responses calculated at different times and transmitted by the second AP, and taking a statistic value of the multiple downlink channel frequency-domain responses calculated at different times to participate in calculation of the uplink-downlink channel response difference between the first AP and the second AP.

3. A base station for calibrating data transmitted by coordinated Access Points (APs), comprising a processor, and a storage device for storing computer executable instructions that when executed by the processor cause the processor to perform steps in an uplink-downlink channel response difference calculation module and a data calibration module, wherein,

the uplink-downlink channel response difference calculation module is configured to obtain an uplink channel frequency-domain response and a downlink channel frequency-domain response between a first AP and a second AP which participate in coordination, divide the uplink channel frequency-domain response by the downlink channel frequency-domain response to obtain an uplink-downlink channel response difference between the first AP and the second AP, and transmit the uplink-downlink channel response difference to the data calibration module;

and

the data calibration module is configured to calibrate the data transmitted by the first AP and the second AP in coordination according to the uplink-downlink channel response difference;

wherein the uplink-downlink channel response difference calculation module is configured to obtain the uplink channel frequency-domain response and the downlink channel frequency-domain response between the first AP and the second AP, which participate in coordination, by the following way;

obtaining a channel frequency-domain response calculated by the second AP at a time t1 according to a calibration sequence received from the first AP, and using the channel frequency-domain response as the downlink channel frequency-domain response between the first AP and the second AP;

obtaining a channel frequency-domain response calculated by the first AP at a time t2 according to a calibration sequence received from the second AP, and using the channel frequency-domain response as the uplink channel frequency-domain response between the first AP and the second AP;

when the first AP and the second AP have not performed self-calibration of their own set of antennas, if the obtained downlink channel frequency-domain response is calculated by the second AP at the time t1 according to the calibration sequence transmitted by the first AP via an antenna Ant(j) and received by the second AP via an antenna Ant(i), obtaining the uplink channel frequency-domain response calculated by the first AP at the time t2 according to the calibration sequence transmitted by the second AP via the antenna Ant(i) and received by the first AP via the antenna Ant(j); and

when the first AP and the second AP have performed self-calibration of their own set of antennas, if the obtained downlink channel frequency-domain response is calculated by the second AP at the time t1 according to the calibration sequence transmitted by the first AP via an antenna Ant(j) and received by the second AP via an antenna Ant(i), obtaining the uplink channel frequency-domain response calculated by the first AP at the time t2 according to the calibration sequence transmitted by the second AP via an antenna Ant(j′

) and received by the first AP via an antenna Ant(i′

);

wherein iε

[0,N−

1], i′

ε

[0,N−

1], jε

[0,N−

1], j′

ε

[0,N−

1], the time t1 is different from the time t2, and N is a number of antennas of the coordinated AP.

4. The base station according to claim 3, wherein, the uplink-downlink channel response difference calculation module is configured to divide the uplink channel frequency-domain response by the downlink channel frequency-domain response to obtain the uplink-downlink channel response difference between the first AP and the second AP by the following way:

obtaining multiple uplink channel frequency-domain responses calculated at different times and transmitted by the first AP, and taking a statistic value of the multiple uplink channel frequency-domain responses calculated at different times to participate in calculation of the uplink-downlink channel response difference between the first AP and the second AP; and

obtaining multiple downlink channel frequency-domain responses calculated at different times and transmitted by the second AP, and taking a statistic value of the multiple downlink channel frequency-domain responses calculated at different times to participate in calculation of the uplink-downlink channel response difference between the first AP and the second AP.