Pilot signal transmitting method, and channel estimation method, apparatus, and system

• US 9,461,860 B2
• Filed: 11/07/2014
• Issued: 10/04/2016
• Est. Priority Date: 05/10/2012
• Status: Active Grant

• Current Assignee: Honor Device Company Limited
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: Tie, Xiaolei, Ma, Xueli, HUA, Meng, Fan, Shuju
• Primary Examiner(s): Vlahos, Sophia
• Application Number:
  US14/536,341
• Publication Number:
  US 20150063493A1
• Time in Patent Office: 697 Days
• US Class Current: 1/1
• CPC Class Codes: H04B 1/0483 Transmitters with multiple parallel paths
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0667 of delayed versions of same signal using space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0684 using different training sequences per antenna
• CPC Class Codes: H04L 1/0643 block codes
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 27/2626 Arrangements specific to the transmitter only
• CPC Class Codes: H04L 5/0025 Spatial division following the spatial signature of the channel
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Embodiments of the present invention disclose a pilot signal transmitting method, and a channel estimation method, an apparatus, and a system. The method includes: within a transmission time interval (TTI), transmitting a first pilot signal (CPICH1) on a first antenna, and transmitting a second pilot signal (CPICH2) on a second antenna; when no first-type terminal is scheduled within coverage of a MIMO system within the TTI, transmitting a third pilot signal (CPICH3) on a third antenna, and transmitting a fourth pilot signal (CPICH4) on a fourth antenna; and when a first-type terminal is scheduled within the coverage of the MIMO system within the TTI, transmitting the CPICH3 and a fifth pilot signal (CPICH5) on the third antenna, and transmitting the CPICH4 and a sixth pilot signal (CPICH6) on the fourth antenna. By using the method, interference of a pilot signal to a legacy terminal can be greatly reduced.

Claims

1. A pilot signal transmitting method for transmitting a pilot signal in a multiple-input multiple-output (MIMO) system, the method comprises:

within a transmission time interval (TTI), transmitting a first pilot signal (CPICH1) on a first antenna, and transmitting at least a portion of a second pilot signal (CPICH2) on a second antenna; and

when no first-type terminal is scheduled within coverage of the MIMO system within the TTI, transmitting a third pilot signal (CPICH3) on a third antenna, and transmitting a fourth pilot signal (CPICH4) on a fourth antenna;

when no legacy terminal is scheduled within coverage of the MIMO system within the TTI, decomposing the CPICH2 into a CPICH2s and a CPICH2e and, when no first-type terminal is scheduled within coverage of the MIMO system within the TTI, transmitting the CPICH2s but not the CPICH2e on the second antenna;

wherein the CPICH1 is used for channel state information (CSI) estimation and data demodulation, the CPICH2 is used for CSI estimation and data demodulation, CPICH2s is a pilot signal required for performing CSI estimation, the CPICH2e is a pilot signal required for performing data demodulation, the CPICH3 is a pilot signal required for performing CSI estimation, and the CPICH4 is a pilot signal required for performing CSI estimation, the MIMO system comprises a 4 Branch MIMO system or an 8 Branch MIMO system, the first-type terminal is a 4 Branch MIMO terminal corresponding to the 4 Branch MIMO system, or a 4 Branch MIMO terminal or an 8 Branch MIMO terminal corresponding to the 8 Branch MIMO system, and wherein the legacy terminal is one of a single-input single-output terminal, a single-input 2-output terminal, or a 2 Branch MIMO terminal.

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

when a first-type terminal is scheduled within the coverage of the MIMO system within the TTI, transmitting the CPICH2e on the second antenna, transmitting the CPICH3 and a fifth pilot signal (CPICH5) on the third antenna, and transmitting the CPICH4 and a sixth pilot signal (CPICH6) on the fourth antenna, wherein the CPICH5 is a pilot signal required for performing data demodulation, and the CPICH6 is a pilot signal required for performing data demodulation.

3. The method according to claim 1, wherein transmitting a third pilot signal (CPICH3) on a third antenna, and transmitting a fourth pilot signal (CPICH4) on a fourth antenna, comprises:

sending the CPICH3 and the CPICH4 through two code channels;

or

sending the CPICH3 and the CPICH4 through one code channel according to two orthogonal space-time block coding based transmit diversity (STTD) pilot patterns.

4. The method according to claim 2, wherein transmitting the CPICH3 and a fifth pilot signal (CPICH5) on the third antenna, and transmitting the CPICH4 and a sixth pilot signal CPICH6 on the fourth antenna, comprises any of:

sending the CPICH3 and the CPICH5 through two code channels, and combining the CPICH4 and the CPICH6 into one pilot signal (CPICH4′

) and sending the CPICH4′

through another code channel;

combining the CPICH3 and the CPICH5 into one pilot signal (CPICH3′

) and sending the CPICH3′

through one code channel, and combining the CPICH4 and the CPICH6 into another pilot signal (CPICH4′

) and sending the CPICH4′

through another code channel;

sending the CPICH3 and the CPICH4 through two code channels, and sending the CPICH5 and the CPICH6 through another code channel according to two orthogonal space-time block coding based transmit diversity pilot (STTD) patterns; and

sending the CPICH3 and the CPICH4 through one code channel according to two orthogonal STTD patterns, and sending the CPICH5 and the CPICH6 through another code channel according to two orthogonal space-time block coding based transmit diversity (STTD) patterns.

5. The method according to claim 2, further comprising:

separately determining, according to transmit powers required by all first-type terminals within the coverage of the MIMO system for performing CSI estimation and channel estimation that is used for data demodulation, a transmit power for transmitting the CPICH3 and the CPICH5 on the third antenna and a transmit power for transmitting the CPICH4 and the CPICH6 on the fourth antenna.

6. The method according to claim 1, wherein:

time sequence boundaries of the CPICH1, the CPICH2, the CPICH3, and the CPICH4 are aligned with a time sequence boundary of a primary common control physical channel (P-CCPCH); and

time sequence boundaries of the CPICH5 and the CPICH6 are aligned with a time sequence boundary of a high speed physical downlink shared channel (HS-PDSCH) that is two timeslots later than the CPICH1, the CPICH2, the CPICH3, and the CPICH4.

7. A communications base station, comprising:

a first antenna, a second antenna, a third antenna, a fourth antenna, and a pilot signal transmitting apparatus, wherein the pilot signal transmitting apparatus comprises;

a first transmitting unit, configured to;

within a transmission time interval (TTI), transmit a first pilot signal (CPICH1) on the first antenna, and transmit at least a portion of a second pilot signal (CPICH2) on the second antenna;

when no legacy terminal is scheduled within coverage of the MIMO system within the TTI, decompose the CPICH2 into a CPICH2s and a CPICH2e and, when no first-type terminal is scheduled within coverage of the MIMO system within the TTI, transmit the CPICH2s but not the CPICH2e on the second antenna; and

a second transmitting unit, configured to;

when no first-type terminal is scheduled within coverage of a MIMO system within the TTI, transmit a third pilot signal (CPICH3) on the third antenna, and transmit a fourth pilot signal (CPICH4) on the fourth antenna;

wherein the CPICH1 is used for channel state information (CSI) estimation and data demodulation, the CPICH2 is used for CSI estimation and data demodulation, the CPICH2s is used for CSI estimation, the CPICH2e is used for data demodulation, the CPICH3 is used for CSI estimation, and the CPICH4 is used for CSI estimation, and wherein the legacy terminal is one of a single-input single-output terminal, a single-input 2-output terminal, or a 2 Branch MIMO terminal.

8. The base station according to claim 7, wherein the pilot signal transmitting apparatus further comprises:

a third transmitting unit, configured to;

when a first-type terminal is scheduled within the coverage of the MIMO system within the TTI, transmit the CPICH3 and a fifth pilot signal (CPICH5) on the third antenna, and transmit the CPICH4 and a sixth pilot signal (CPICH6) on the fourth antenna;

wherein the first transmitting unit is configured to transmit the CPICH2e on the second antenna when a first-type terminal is scheduled within the coverage of the MIMO system within the TTI;

wherein the CPICH3 is used for CSI estimation, the CPICH4 is used for CSI estimation, the CPICH5 is used for data demodulation, and the CPICH6 is used for data demodulation.

9. The base station according to claim 8, wherein the pilot signal transmitting apparatus further comprises:

a transmit power determining unit, configured to;

separately determine a transmit power of the first transmitting unit on the first antenna and a transmit power of the first transmitting unit on the second antenna according to requirements of powers required by all terminals within the coverage for performing both CSI estimation and channel estimation that is used for data demodulation; and

separately determine a transmit power of the second transmitting unit on the third antenna and a transmit power of the second transmitting unit on the fourth antenna according to requirements of powers required by all first-type terminals within the coverage for performing CSI estimation;

or separately determine, according to requirements of powers required by all first-type terminals within the coverage for performing both CSI estimation and channel estimation that is used for data demodulation, a transmit power for the third transmitting unit to transmit the CPICH3 and the CPICH5 on the third antenna and a transmit power for the third transmitting unit to transmit the CPICH4 and the CPICH6 on the fourth antenna.

10. The base station according to claim 7, wherein:

the first transmitting unit is configured to send the CPICH1 through a first code channel and send the CPICH2 through a second code channel; and

the second transmitting unit is configured to send the CPICH3 through a third code channel and send the CPICH4 through a fourth code channel;

or configured to send the CPICH3 and the CPICH4 through a third code channel according to two orthogonal space-time block coding based transmit diversity pilot patterns (STTD) patterns.

11. The base station according to claim 8, wherein the third transmitting unit is configured to send any of:

the CPICH3 through a third code channel, send the CPICH5 through a fourth code channel, and send, through a fifth code channel, a pilot signal (CPICH4′

) that is obtained by combining the CPICH4 and the CPICH6;

through a third code channel, a pilot signal (CPICH3′

) that is obtained by combining the CPICH3 and the CPICH5 and send, through a fourth code channel, another pilot signal (CPICH4′

) that is obtained by combining the CPICH4 and the CPICH6;

the CPICH3 through a third code channel, send the CPICH4 through a fourth code channel, and send the CPICH5 and the CPICH6 through a fifth code channel according to two orthogonal space-time block coding based transmit diversity pilot patterns (STTD) patterns; and

the CPICH3 and the CPICH4 through a third code channel according to two orthogonal STTD patterns and send the CPICH5 and the CPICH6 through a fourth code channel according to two orthogonal STTD patterns.

12. The base station according to claim 8, wherein the pilot signal transmitting apparatus further comprises:

a judging unit, configured to;

determine whether a first-type terminal is scheduled in the MIMO system within the TTI, and control, according to a result of the determining, the second transmitting unit or the third transmitting unit to transmit a pilot signal;

if no first-type terminal is scheduled in the MIMO system within the TTI, control the second transmitting unit to transmit a pilot signal; and

if a first-type terminal is scheduled in the MIMO system within the TTI, control the third transmitting unit to transmit a pilot signal.