# US 2014/0192921 A1 · TAE/FAE Compensation for Antenna Ports in CoMP Transmission

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- Number: US 2014/0192921 A1
- Document ID: US20140192921A1
- Status: Published application
- Kind: A1
- Application number: 14/238,344
- Filed: 2011-12-27
- Published: 2014-07-10
- Earliest claimed: 2011-08-12
- Assignees: Telefonaktiebolaget L M Ericsson (publ)
- Inventors: Hai Wang; Yang Hu; Shaohua Li; Jianfeng Wang
- Web page: https://patentgrep.com/patent/US20140192921A1

## CPC

- H04L 27/2646: {using feedback from receiver for adjusting OFDM transmission parameters, e.g. transmission timing or guard interval length}
- H04B 7/063: {Parameters other than those covered in groups H04B7/0623 - H04B7/0634, e.g. channel matrix rank or transmit mode selection}
- H04B 7/0632: {Channel quality parameters, e.g. channel quality indicator [CQI]}
- H04B 7/0639: {Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection}
- H04L 1/0026: {Transmission of channel quality indication}
- H04L 1/06: using space diversity
- H04L 1/20: using signal quality detector
- H04L 2001/0092: {Error control systems characterised by the topology of the transmission link}
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04B: TRANSMISSION

## Abstract

The present invention discloses a user equipment (UE) (100), comprising: a first measuring unit (110) adapted to measure time alignment error (TAE) and/or frequency alignment error (FAE) for antenna ports belonging to transmission point devices in Coordinated Multipoint Transmission (CoMP), the TAE including internal TAE and/or external TAE; and a first feedback unit (120) adapted to feedback the measured internal TAE, and/or external TAE, and/or FAE to at least one of the transmission point devices. The present invention provides a simple, direct and efficient approach for measuring and feeding back the cell-specific internal TAE and/or the UE-specific external TAE/FAE by UE and compensating the TAE/FAE by the transmission point device in the CoMP transmission, so that the CoMP transmission can properly operate.

## Claims

### Claim at position 1

1-37. (canceled)

### Claim 38

A user equipment (UE), comprising:
a first measuring unit adapted to measure at least one of time alignment error (TAE) and frequency alignment error (FAE), for antenna ports belonging to transmission point devices in Coordinated Multipoint Transmission (CoMP), the TAE including at least one of internal TAE and external TAE; and
a first feedback unit adapted to feed back at least one of the measured internal TAE, the measured external TAE, and the measured FAE, to at least one of the transmission point devices.

### Claim 39 (depends on 38)

The UE according to claim 38, further comprising a calculating unit adapted to calculate at least one of a precoding matrix index (PMI), a channel quality indicator (CQI), and a rank indicator (RI) on the basis of a channel compensated with at least one of the measured internal TAE, the measured external TAE, and the measured FAE, and wherein the first feedback unit is further adapted to feed back a result of the calculation to the at least one of the transmission point devices.

### Claim 40

A transmission point device for compensating at least one of time alignment error (TAE) and frequency alignment error (FAE), for antenna ports belonging to transmission point devices in Coordinated Multipoint Transmission (CoMP), the TAE including at least one of an internal TAE and an external TAE, and wherein the transmission point device comprises:
a receiving unit adapted to receive at least one of internal TAE measurements, external TAE measurements, and FAE measurements, from one or more user equipments (UEs); and
a compensating unit adapted to compensate for at least one of the internal TAE, the external TAE, and the FAE, for respective antenna ports, on the basis of any one or more of the received internal TAE measurements, the received external TAE measurements, and the received FAE measurements.

### Claim 41 (depends on 40)

The transmission point device according to claim 40, further comprising a determining unit adapted to determine, from the one or more UEs, at least one of a first set of UEs adapted to measure the internal TAE and feed back the internal TAE measurements, a second set of UEs adapted to measure the external TAE and feed back the external TAE measurements, and a third set of UEs adapted to measure the FAE and feed back the FAE measurements.

### Claim 42 (depends on 41)

The transmission point device according to claim 41, further comprising an averaging unit adapted to perform at least one:
average a plurality of the internal TAE measurements received from UEs that are among the first set of UEs and associated with a same transmission point; and
average a plurality of the FAE measurements received from UEs that are among the third set of UEs and associated with a same pair of transmission point devices.

### Claim 43

A method for use in a user equipment (UE), comprising:
measuring at least one of time alignment error (TAE) and frequency alignment error (FAE), for antenna ports belonging to transmission point devices in Coordinated Multipoint Transmission (CoMP), the TAE including at least one of internal TAE and external TAE; and
feeding back at least one of measured internal TAE, the measured external TAE, and the measured FAE, to at least one of the transmission point devices.

### Claim 44 (depends on 43)

The method according to claim 43, wherein the internal TAE is TAE among antenna ports in a same transmission point device, the external TAE is TAE among antenna ports in different transmission point devices, and the FAE is at least one of FAE between a serving transmission point device and any other transmission point device and FAE among antenna ports in a same transmission point device.

### Claim 45 (depends on 43)

The method according to claim 43, wherein the internal TAE is cell-specific, and the external TAE and the FAE are UE-specific.

### Claim 46 (depends on 43)

The method according to claim 43, further comprising:
calculating at least one of a precoding matrix index (PMI), a channel quality indicator (CQI), and a rank indicator (RI) on the basis of a channel compensated with any one or more of the measured internal TAE, the measured external TAE, and the measured FAE; and
feeding back a result of the calculation to the at least one of the transmission point devices.

### Claim 47 (depends on 43)

The method according to claim 43, wherein the step of measuring the TAE is performed on the basis of phase difference between antenna ports of different frequencies at a specific time, or wherein the step of measuring the FAE is performed on the basis of phase difference between antenna ports at different times of a specific frequency.

### Claim 48 (depends on 43)

The method according to claim 43, wherein the UE belongs to at least respective one of a first set of UEs, a second set of UEs, and a third set of UEs, and wherein:
the first set of UEs each measuring the internal TAE and feeding back internal TAE measurements to the at least one of the transmission point devices;
the second set of UEs each measuring the external TAE and feeding back external TAE measurements to the at least one of the transmission point devices; and
the third set of UEs each measuring the FAE and feeding back FAE measurement to the at least one of the transmission point devices.

### Claim 49

A method for compensating for at least one of time alignment error (TAE) and frequency alignment error (FAE), for antenna ports belonging to transmission point devices in Coordinated Multipoint Transmission (CoMP), the TAE including at least one of internal TAE and external TAE, and the method performed by a transmission point device and comprising:
receiving one or more of internal TAE measurements, external TAE measurements, and FAE measurements from one or more user equipments (UEs); and
compensating at least one of the internal TAE, the external TAE, and the FAE for respective antenna ports, on the basis of any one or more of the received internal TAE measurements, the received external TAE measurements, and the received FAE measurements.

### Claim 50 (depends on 49)

The method according to claim 49, wherein the internal TAE is TAE among antenna ports in a same transmission point device, the external TAE is TAE among antenna ports in different transmission point devices, and the FAE is at least one of FAE between a serving transmission point device and any other transmission point device and FAE among antenna ports in a same transmission point device.

### Claim 51 (depends on 49)

The method according to claim 49, wherein the internal TAE is cell-specific, and the external TAE and FAE are UE-specific.

### Claim 52 (depends on 49)

The method according to claim 49, further comprising determining, from the one or more UEs, at least one of:
a first set of UEs adapted to measure and feed back the internal TAE measurements;
a second set of UEs adapted to measure and feed back the external TAE measurements;
a third set of UEs adapted to measure and feed back the FAE measurements.

### Claim 53 (depends on 52)

The method according to claim 52, wherein the receiving step includes at least one of: receiving the internal TAE measurements from the first group of UEs, receiving the external TAE measurements from the second group of UEs, and receiving the FAE measurements from the third group of UEs.

### Claim 54 (depends on 52)

The method according to claim 52, further comprising at least one of:
averaging a plurality of internal TAE measurements received from UEs that are among the first set of UEs and associated with a same transmission point device; and
averaging a plurality of FAE measurements received from UEs that are among the third set of UEs and associated with a same pair of transmission point devices.

### Claim 55 (depends on 54)

The method according to claim 54, wherein the compensating step includes compensating any one or more of the internal TAE, the external TAE, and the FAE for respective antenna ports, on the basis of any one or more of the averaged internal TAE measurements, the external TAE measurements, and the averaged FAE measurements.

### Claim 56 (depends on 52)

The method according to claim 52, wherein the step of determining the first set of UEs is performed according to channel conditions thereof, the step of determining the second set of UEs is performed according to whether a UE is the UE being serviced by the CoMP transmission, and the step of determining the third set of UEs is performed according to channel conditions thereof.

### Claim 57 (depends on 49)

The method according to claim 49, wherein the step of compensating comprises compensating phase differences for signals transmitted from the transmission point devices to respective antenna ports that are due to any one or more of the internal TAE, the external TAE, and the FAE, on the basis of any one or more of the internal TAE measurements, the external TAE measurements, and the FAE measurements.