Reference signal transmission method for downlink multiple input multiple output system

• US 8,929,389 B2
• Filed: 11/16/2012
• Issued: 01/06/2015
• Est. Priority Date: 08/05/2008
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Lee, Jung Hoon, Seo, Dong Youn, Kim, Ki Jun, Ahn, Joon Kui
• Primary Examiner(s): Ng, Fan
• Application Number:
  US13/679,759
• Publication Number:
  US 20130101004A1
• Time in Patent Office: 781 Days
• Field of Search: 370464-545
• US Class Current: 370/464
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/005 of common pilots, i.e. pilots destined for multiple users or terminals
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 88/02 Terminal devices
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

A reference signal transmission method in a downlink MIMO system is disclosed. The downlink MIMO system supports a first UE supporting N transmission antennas among a total of M transmission antennas (where M>N) and a second UE supporting the M transmission antennas. The method includes transmitting, by a base station (BS), subframe-associated information which designates a first subframe in which data for the first UE and the second UE is transmitted and a second subframe in which data only for the second UE can be transmitted within a radio frame having a plurality of subframes, and transmitting the first subframe and the second subframe. Reference signals corresponding to antenna ports ‘0’ to ‘N−1’ of the N antennas are mapped to the first subframe, and reference signals corresponding to antenna ports ‘0’ to ‘M−1’ of the M antennas are mapped to the second subframe.

Claims

1. A method for transmitting at least one first type reference signal and at least one second type reference signal for channel measurement in an OFDM (Orthogonal Frequency Division Multiplex) system, the method comprising:

transmitting, by a base station to a user equipment, information indicating an occurrence of a first subframe including the at least one second type reference signal; and

transmitting, by the base station to the user equipment, the first subframe including M number of reference signals, the M number of reference signals including N (N<

M) number of the at least one first type reference signal and M−

N number of the at least one second type reference signal; and

transmitting, by the base station to the user equipment, a second subframe including the N number of the at least one first type reference signal,

wherein each of the N number of the at least one first type reference signal corresponds to each of N antenna ports, and each of the M number of reference signals corresponds to each of M number of antenna ports, and

wherein each of the first subframe and the second subframe includes a plurality of OFDM symbols.

2. The method according to claim 1,

wherein positions of resource elements to which reference signals for antenna port index 0 to N−

1 among the M antenna ports are mapped in the first subframe, are the same as positions of resource elements to which reference signals for antenna port index 0 to N−

1 of the N antenna ports are mapped in the second subframe.

3. The method according to claim 1,

wherein control information is transmitted in a first part of the plurality of OFDM symbols in the first subframe,

wherein data is transmitted in a second part of the plurality of OFDM symbols in the first subframe, and

wherein the M−

N number of the at least one second type reference signal is mapped to the second part of the first subframe.

4. The method according to claim 1, further comprising:

receiving channel information from the user equipment,

wherein the channel information is generated by the user equipment by using reference signals transmitted in at least one of the first subframe or the second subframe.

5. A method for transmitting channel information using at least one first type reference signal and at least one second type reference signal for channel measurement in an OFDM (Orthogonal Frequency Division Multiplex) system, the method comprising:

receiving, by a user equipment from a base station, information indicating an occurrence of a first subframe including the at least one second type reference signal;

receiving, by the user equipment from the base station, the first subframe including M number of reference signals, the M number of reference signals including N (N<

M) number of the at least one first type reference signal and M−

N number of the at least one second type reference signal;

receiving, by the user equipment from the base station, a second subframe including the N number of the at least one first type reference signal;

generating the channel information by using reference signals transmitted in at least one of the first subframe or the second subframe; and

transmitting the generated channel information to the base station,

wherein each of the N number of the at least one first type reference signal corresponds to each of N antenna ports, and each of the M number of reference signals corresponds to each of M number of antenna ports, and

wherein each of the first subframe and the second subframe includes a plurality of OFDM symbols.

6. The method according to claim 5,

wherein positions of resource elements to which reference signals for antenna port index 0 to N−

1 among the M antenna ports are mapped in the first subframe, are the same as positions of resource elements to which reference signals for antenna port index 0 to N−

1 of the N antenna ports are mapped in the second subframe.

7. The method according to claim 5,

wherein control information is transmitted in a first part of the plurality of OFDM symbols in the first subframe,

wherein data is transmitted in a second part of the plurality of OFDM symbols in the first subframe, and

wherein the M−

N number of the at least one second type reference signal is mapped to the second part of the first subframe.

8. A base station for transmitting at least one first type reference signal and at least one second type reference signal for channel measurement in an OFDM (Orthogonal Frequency Division Multiplex) system, the base station comprising:

a processing unit configured to generate information indicating an occurrence of a first subframe including the at least one second type reference signal; and

a RF (Radio Frequency) unit configured to;

transmit, to a user equipment, the information indicating the occurrence of the first subframe,

transmit, to the user equipment, the first subframe including M number of reference signals, the M number of reference signals including N (N<

M) number of the at least one first type reference signal and M−

N number of the at least one second type reference signal, and

transmit, to the user equipment, a second subframe including the N number of the at least one first type reference signal,

wherein each of the N number of the at least one first type reference signal corresponds to each of N antenna ports, and each of the M number of reference signals corresponds to each of M number of antenna ports, and

wherein each of the first subframe and the second subframe includes a plurality of OFDM symbols.

9. A user equipment for transmitting channel information using at least one first type reference signal and at least one second type reference signal for channel measurement in an OFDM (Orthogonal Frequency Division Multiplex) system, the user equipment comprising:

a RF (Radio Frequency) unit configured to;

receive, from a base station, information indicating an occurrence of a first subframe including the at least one second type reference signal,

receive, from the base station, the first subframe including M number of reference signals, the M number of reference signals including N (N<

M) number of the at least one first type reference signal and M−

N number of the at least one second type reference signal, and

receive, from the base station, a second subframe including the N number of the at least one first type reference signal; and

a processing unit configured to generate the channel information by using reference signals transmitted in at least one of the first subframe or the second subframe,

wherein the RF unit is further configured to transmit the generated channel information to the base station,

wherein each of the N number of the at least one first type reference signal corresponds to each of N antenna ports, and each of the M number of reference signals corresponds to each of M number of antenna ports, and

wherein each of the first subframe and the second subframe includes a plurality of OFDM symbols.