Antenna port mapping for demodulation reference signals

Patent metadata

Field	Value
Publication number	US-11019526-B2
Application number	US-202016905033-A
Country	US
Kind code	B2
Filing date	Jun 18, 2020
Priority date	Jan 20, 2010
Publication date	May 25, 2021
Grant date	May 25, 2021

Abstract

A unified, rank independent mapping between antenna ports and group/code pairs. Each antenna port is uniquely associated with one code division multiplexing (CDM) group and one orthogonal cover code (OCC). The mapping between antenna ports and group/code pairs is chosen such that, for a given antenna port, the CDM group and OCC will be the same for every transmission rank.

First claim

What is claimed is:

1. A method, implemented by a base station, for transmitting demodulation reference signals to a user terminal, the method comprising:
determining a selected transmission rank from a plurality of transmission ranks for a downlink transmission to the user terminal;
determining one or more antenna ports for the downlink transmission, wherein each of the one or more antenna ports is defined by a group and code pair in a set of group and code pairs, wherein each group and code pair in the set of group and code pairs comprises a code division multiplexing group and orthogonal cover code;
for each transmission rank of the plurality of transmission ranks, mapping antenna ports to corresponding group and code pairs in the set of group and code pairs such that mapping of antenna ports to corresponding group and code pairs in the set of group and code pairs for a highest transmission rank of the plurality of transmission ranks is a superset of mappings of antenna ports to corresponding group and code pairs in the set of group and code pairs for all other transmission ranks of the plurality of transmission ranks that are lower than the highest transmission rank; and
transmitting the demodulation reference signals over the one or more antenna ports corresponding to the selected transmission rank.

2. The method of claim 1 , wherein mapping of antenna ports to corresponding group and code pairs in the set of group and code pairs for each of the lower transmission ranks is a subset of mapping of antenna ports to corresponding group and code pairs in the set of group and code pairs for a next higher transmission rank.

3. The method of claim 1 :
wherein the orthogonal cover codes comprise length-4 orthogonal cover codes; and
wherein the mapping of the antenna ports to the corresponding group and code pairs is such that, for selected antenna ports, the length-4 orthogonal cover codes comprise two length-2 orthogonal cover codes for channel estimation.

4. The method of claim 2 , further comprising sending a control signal to the user terminal to indicate whether channel estimation is performed using length-2 or length-4 orthogonal cover codes for the determined one or more antenna ports.

5. A method, implemented by a user terminal, for receiving demodulation reference signals transmitted by a base station, the method comprising:
determining a selected transmission rank from a plurality of transmission ranks for a downlink transmission to the user terminal;
determining one or more antenna ports for the downlink transmission, wherein each of the one or more antenna ports is defined by a group and code pair in a set of group and code pairs, wherein each group and code pair in the set of group and code pairs comprises a code division multiplexing group and orthogonal cover code;
for each transmission rank of the plurality of transmission ranks, mapping antenna ports to corresponding group and code pairs in the set of group and code pairs such that mapping of antenna ports to corresponding group and code pairs in the set of group and code pairs for a highest transmission rank of the plurality of transmission ranks is a superset of mappings of antenna ports to corresponding group and code pairs in the set of group and code pairs for all other transmission ranks of the plurality of transmission ranks that are lower than the highest transmission rank; and
receiving the demodulation reference signals over the one or more antenna ports corresponding to the selected transmission rank.

6. The method of claim 5 , wherein mapping of antenna ports to corresponding group and code pairs in the set of group and code pairs for each of the lower transmission ranks is a subset of mapping of antenna ports to corresponding group and code pairs in the set of group and code pairs for a next higher transmission rank.

7. The method of claim 5 :
wherein the orthogonal cover codes comprise length-4 orthogonal cover codes; and
wherein the mapping of the antenna ports to the corresponding group and code pairs is such that, for selected antenna ports, the length-4 orthogonal cover codes comprise two length-2 orthogonal cover codes for channel estimation.

8. The method of claim 7 , further receiving a control signal from the base station and performing channel estimation using either length-2 or length-4 orthogonal cover codes for the determined one or more antenna ports depending on the control signal.

9. A base station, comprising:
a plurality of transmit antennas;
a transmitter operatively connected to the transmit antennas, the transmitter including a transmit signal processor and transmit controller;
the transmitter configured to:
determine a selected transmission rank from a plurality of transmission ranks for a downlink transmission to a user terminal;
determine one or more antenna ports for the downlink transmission, wherein each of the one or more antenna port is defined by a group and code pair in a set of group and code pairs, wherein each group and code pair in the set of group and code pairs comprises a code division multiplexing group and orthogonal cover code;
for each transmission rank of the plurality of transmission ranks, map antenna ports to corresponding group and code pairs in the set of group and code pairs such that mapping of antenna ports to corresponding group and code pairs in the set of group and code pairs for a highest transmission rank of the plurality of transmission ranks is a superset of mappings of antenna ports to corresponding group and code pairs in the set of group and code pairs for all other transmission ranks of the plurality of transmission ranks that are lower than the highest transmission rank;
transmit demodulation reference signals over the one or more antenna ports corresponding to the selected transmission rank.

10. The base station of claim 9 , wherein mapping of antenna ports to corresponding group and code pairs fin the set of group and code pairs for each of the lower transmission ranks is a subset of mapping of antenna ports to group and code pairs in the set of group and code pairs for a next higher transmission rank.

11. The base station of claim 9 :
wherein the orthogonal cover codes comprise length-4 orthogonal cover codes; and
wherein the mapping of the one or more antenna ports to the one or more corresponding group and code pairs is such that, for selected antenna ports, the length-4 orthogonal cover codes comprise two length-2 orthogonal cover codes for channel estimation.

12. The base station of claim 11 , wherein a base station is further configured to send a control signal to a user terminal to indicate whether channel estimation is performed using length-2 or length-4 orthogonal cover codes for the determined one or more antenna ports.

13. A user terminal, comprising:
a plurality of receive antennas;
a receiver operatively connected to the receive antennas, the receiver including a receive signal processor and receive controller;
wherein the receiver is configured to:
determine a selected transmission rank from a plurality of transmission ranks for a downlink transmission to the user terminal;
determine one or more antenna ports for the downlink transmission, wherein each of the one or more antenna ports is defined by a group and code pair in a set of group and code pairs, wherein each group and code pair in the set of group and code pairs comprises a code division multiplexing group and orthogonal cover code;
for each transmission rank of the plurality of transmission ranks, map antenna ports to corresponding group and code pairs in the set of group and code pairs such that mapping of antenna ports

Assignees

• Ericsson Telefon Ab L M
• Telefonaktiebolaget Lm Ericcson Publ

Inventors

• Hu Yang
• Astely David
• Hammarwall David
• Jöngren George
• Song Xinghua
• Wang Jianfeng

Classifications

• H04W72/563

  of the wireless resources · CPC title

• H04W72/23 Primary

  in the downlink direction of a wireless link, i.e. towards a terminal · CPC title

• H04L5/0026 Primary

  Division using four or more dimensions, e.g. beam steering or quasi-co-location [QCL] · CPC title

• H04W72/0453

  Resources in frequency domain, e.g. a carrier in FDMA · CPC title

• H04W28/0263 Primary

  involving mapping traffic to individual bearers or channels, e.g. traffic flow template [TFT] · CPC title