Terminal, base station, wireless communication system, and method of acquiring channel state information

Patent metadata

Field	Value
Publication number	US-10742277-B2
Application number	US-201816500055-A
Country	US
Kind code	B2
Filing date	Apr 4, 2018
Priority date	Apr 6, 2017
Publication date	Aug 11, 2020
Grant date	Aug 11, 2020

Abstract

A base station includes a memory holding information on P terminals in connecting to the base station, where P is an integer of 3 or more, a determination unit that determines L terminals to transmit a reference symbol used for measurement of channel state information indicating a state of a propagation path to the base station from among the P terminals based on the information on the P terminals, at every data transmission cycle, where L is an integer satisfying 2≤L<P, a selector that selects M terminals capable of spatial multiplexing communication in the data transmission cycle based on a measurement result of the channel state information based on reception of the reference symbol transmitted from L terminals, where M is an integer satisfying 2≤M≤L, and receives respective pieces of data transmitted from the M terminals via a plurality of antennas.

First claim

The invention claimed is:

1. A base station capable of wireless communication with a plurality of terminals, the base station comprising:
a memory that holds information on P terminals being currently connected to the base station, where P is an integer of 3 or more, and where the information on the P terminals includes transmission history information indicating presence or absence of data transmission to the base station at every past data transmission cycle;
a processor that
determines L terminals that are to transmit a reference symbol used for measurement of channel state information indicating a state of a propagation path to the base station from among the P terminals based on the information on the P terminals, at every data transmission cycle, where L is an integer satisfying 2≤L<P, wherein the processor determines a terminal, whose transmission history information indicates no data transmission to the base station for the past n data transmission cycles where n is an integer of 2 or more, as one of the L terminals that are to transmit the reference symbol; and
selects M terminals that are capable of spatial multiplexing communication in the data transmission cycle according to the channel state information based on the reference symbols transmitted from the L terminals, where M is an integer satisfying 2≤M≤L; and

a communicator that receives data transmitted from the M terminals using the spatial multiplexing communication via a plurality of antennas.

2. The base station according to claim 1 , wherein the information on the P terminals includes terminal identification information on respective terminals currently connected to the base station, and
the processor determines the L terminals in order of the terminal identification information on the respective terminals.

3. The base station according to claim 1 , wherein the information on the P terminals includes information on an amount of uplink data to be transmitted from respective terminals, and
the processor determines the L terminals in preference to a terminal with a larger amount of uplink data.

4. The base station according to claim 1 , wherein the information on the P terminals includes rank information in a predetermined agreement, and
the processor determines the L terminals in preference to a terminal having higher rank information based on the rank information in the predetermined agreement.

5. A method of acquiring channel state information in a base station capable of wireless communication with a plurality of terminals, the method comprising:
a step of holding information on P terminals currently connected to the base station, where P is an integer of 3 or more, and where the information on the P terminals includes transmission history information indicating presence or absence of data transmission to the base station at every past data transmission cycle;
a step of determining L terminals that are to transmit a reference symbol used for measurement of channel state information indicating a state of a propagation path to the base station from among the P terminals based on the information on the P terminals, at every data transmission cycle, where L is an integer satisfying 2≤L<P, wherein the determining includes determining a terminal, whose transmission history information indicates no data transmission to the base station for the past n data transmission cycles where n is an integer of 2 or more, as one of the L terminals that are to transmit the reference symbol;
a step of selecting M terminals that are capable of spatial multiplexing communication in the data transmission cycle according to the channel state information based on the reference symbols transmitted from the L terminals, where M is an integer satisfying 2≤M<L; and
a step of receiving respective data transmitted from the M terminals by using the spatial multiplexing communication via a plurality of antennas.

6. A wireless communication system capable of wireless communication between a plurality of terminals and a base station,
wherein the base station
holds information on P terminals currently connected to the base station, where P is an integer of 3 or more, and where the information on the P terminals includes transmission history information indicating presence or absence of data transmission to the base station at every past data transmission cycle, and
determines L terminals that are to transmit a reference symbol used for measurement of channel state information indicating a state of a propagation path to the base station from among the P terminals based on the information on the P terminals, at every data transmission cycle, and transmits a transmission instruction for the reference symbol to the L terminals, where L is an integer satisfying 2≤L<P, and determines a terminal, whose transmission history information indicates no data transmission to the base station for the past n data transmission cycles where n is an integer of 2 or more, as one of the L terminals that are to transmit the reference symbol,
the terminals transmit the reference symbol based on the transmission instruction for the reference symbol transmitted from the base station, and
the base station
selects M terminals that are capable of spatial multiplexing communication in the data transmission cycle according to the channel state information based on the reference symbols transmitted from the L terminals, where M is an integer satisfying 2≤M≤L, and
receives data transmitted from the M terminals using the spatial multiplexing communication via a plurality of antennas.

7. A terminal capable of communicating with a base station, the terminal comprising:
a memory that holds information on the terminal itself, where the information on the terminal itself includes transmission history information indicating presence or absence of data transmission to the base station at every past data transmission cycle;
a processor that determines necessity of transmitting a reference symbol used for measurement of channel state information indicating a state of a propagation path to the base station based on the information on the terminal itself, at every data transmission cycle, wherein the processor determines to transmit the reference symbol when the transmission history information indicates no data transmission to the base station for the past n data transmission cycles where n is an integer of 2 or more; and
a communicator that transmits the reference symbol to the base station based on the determination to transmit the reference symbol,
wherein the communicator transmits data to the base station in a case where the terminal is one of M terminals capable of spatial multiplexing communication with the base station in the data transmission cycle that are selected according to the channel state information based on the reference symbols transmitted to the base station, where M is a value of 2 or more.

8. The terminal according to claim 7 , wherein the information on the terminal itself includes group information corresponding to an identification number of the terminal itself, and
the processor determines whether or not to transmit the reference symbol based on the group information.

9. The terminal according to claim 7 , wherein the value n is a predefined integer value of 2 or more.

10. The terminal according to claim 7 , wherein the information on the terminal itself further includes information on an amount of data to be transmitted to the base station, and
in a case where the amount of data to be transmitted to the base station is larger than a predetermined threshold, the processor sets the value n to be smaller than a current value according to the amount of data.

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Kato Osamu
• Shimizu Noriyuki
• Shingu Hideki

Classifications

• H04B7/0452 Primary

  Multi-user MIMO systems · CPC title

• H04W72/12

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• H04W16/28

  using beam steering · CPC title

• H04B7/0626

  Channel coefficients, e.g. channel state information [CSI] · CPC title

• H04B7/0643

  Feedback on request · CPC title