MIMO WLAN system

• US 9,013,974 B2
• Filed: 08/13/2014
• Issued: 04/21/2015
• Est. Priority Date: 10/25/2002
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Walton, Jay Rodney, Wallace, Mark S., Ketchum, John W., Howard, Steven J.
• Primary Examiner(s): Javaid, Jamal
• Application Number:
  US14/458,933
• Publication Number:
  US 20140348258A1
• Time in Patent Office: 251 Days
• Field of Search: 370/280, 370/338, 370/241, 370/208, 370/210, 375/260, 375/299, 375/267, 375/210, 375/295, 375/367, 375/324, 375/326, 455/101, 455/132, 455/522, 455/562.1
• US Class Current: 370/208
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04B 7/0421 utilizing implicit feedback, e.g. steered pilot signals
• CPC Class Codes: H04B 7/043 using best eigenmode, e.g. beam forming or beam steering
• CPC Class Codes: H04B 7/0443 utilizing "waterfilling" technique
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0689 using different transmission schemes, at least one of them being a diversity transmission scheme
• CPC Class Codes: H04B 7/0697 using spatial multiplexing
• CPC Class Codes: H04B 7/0854 using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion
• CPC Class Codes: H04B 7/0871 using different reception schemes, at least one of them being a diversity reception scheme
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0017 where the mode-switching is based on Quality of Service requirement
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0059 Convolutional codes
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 1/0069 Puncturing patterns
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/0606 Space-frequency coding
• CPC Class Codes: H04L 1/0625 Transmitter arrangements
• CPC Class Codes: H04L 1/0656 Cyclotomic systems, e.g. Bell Labs Layered Space-Time [BLAST]
• CPC Class Codes: H04L 1/08 : by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 1/16 : in which the return channel carries supervisory signals, e.g. repetition request signals
• CPC Class Codes: H04L 1/1887 : Scheduling and prioritising arrangements
• CPC Class Codes: H04L 2025/03414 : Multicarrier
• CPC Class Codes: H04L 2025/03426 : transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 25/0204 : of multiple channels
• CPC Class Codes: H04L 25/0226 : sounding signals per se
• CPC Class Codes: H04L 25/0228 : with direct estimation from sounding signals
• CPC Class Codes: H04L 25/0248 : Eigen-space methods
• CPC Class Codes: H04L 25/03343 : Arrangements at the transmitter end
• CPC Class Codes: H04L 27/2602 : Signal structure
• CPC Class Codes: H04L 27/2607 : Cyclic extensions
• CPC Class Codes: H04L 27/2647 : Arrangements specific to the receiver only equalisation H04L27/01
• 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: H04W 28/20 : Negotiating bandwidth
• CPC Class Codes: H04W 28/22 : Negotiating communication rate
• CPC Class Codes: H04W 52/42 : in systems with time, space, frequency or polarisation diversity
• CPC Class Codes: H04W 52/50 : at the moment of starting communication in a multiple access environment
• CPC Class Codes: H04W 72/12 : Wireless traffic scheduling
• CPC Class Codes: H04W 84/12 : WLAN [Wireless Local Area Networks]

Abstract

A multiple-access MIMO WLAN system that employs MIMO, OFDM, and TDD. The system (1) uses a channel structure with a number of configurable transport channels, (2) supports multiple rates and transmission modes, which are configurable based on channel conditions and user terminal capabilities, (3) employs a pilot structure with several types of pilot (e.g., beacon, MIMO, steered reference, and carrier pilots) for different functions, (4) implements rate, timing, and power control loops for proper system operation, and (5) employs random access for system access by the user terminals, fast acknowledgment, and quick resource assignments. Calibration may be performed to account for differences in the frequency responses of transmit/receive chains at the access point and user terminals. The spatial processing may then be simplified by taking advantage of the reciprocal nature of the downlink and uplink and the calibration.

Claims

1. A method of transmitting and receiving pilots in a wireless multiple-input multiple-output (MIMO) communication system, comprising:

transmitting a MIMO pilot on a forward channel from a plurality of antennas and on a first communication link via a plurality of transmission channels, wherein the MIMO pilot comprises a plurality of pilot transmissions sent from the plurality of antennas, and wherein the pilot transmission from each antenna is configured to be identifiable by a communicating entity receiving the MIMO pilot; and

receiving a steered pilot on a reverse channel via a plurality of eigenmodes of a second communication link from the communicating entity, wherein at least some of the plurality of eigenmodes are used for data transmission, and wherein the steered pilot is generated based on the MIMO pilot and a channel response matrix for the plurality of transmission channels.

2. The method of claim 1, wherein the steered pilot comprises a specific set of modulation symbols that is subjected to spatial processing prior to transmission.

3. The method of claim 1, wherein the MIMO communication system supports one or more of a single-input multiple-output (SIMO) transmission mode, a diversity transmission mode, a beam-steering transmission mode, a beam-forming transmission mode, a non-steered spatial multiplexing transmission mode, a multi-user spatial multiplexing transmission mode, or a spatial multiplexing transmission mode.

4. The method of claim 1, wherein the pilot transmission from each antenna is associated with a different orthogonal code.

5. The method of claim 1, further comprising:

estimating a channel response of at least one eigenmode for the communicating entity based on the received steered pilot.

6. The method of claim 5, further comprising:

deriving a matched filter based on the estimated channel response of the at least one eigenmode, wherein the matched filter is used for matched filtering of a data transmission received via the at least one eigenmode from the communication entity.

7. The method of claim 1, wherein the steering pilot is transmitted at full transmit power from a plurality of antennas at the communicating entity.

8. An apparatus for transmitting and receiving pilots in a wireless multiple-input multiple-output (MIMO) communication system, comprising:

a transmit spatial processor operative to generate a MIMO pilot for transmission, on a forward channel, from a plurality of antennas and on a first communication link via a plurality of transmission channels, wherein the MIMO pilot comprises a plurality of pilot transmissions sent from the plurality of antennas, and wherein the pilot transmission from each antenna is configured to be identifiable by a communicating entity receiving the MIMO pilot; and

a receive spatial processor operative to process a steered pilot received on a reverse channel via a plurality of eigenmodes of a second communication link from the communicating entity, wherein at least some of the plurality of eigenmodes are used for data transmission, and wherein the steered pilot is generated based on the MIMO pilot and a channel response matrix for the plurality of transmission channels.

9. The apparatus of claim 8, wherein the steered pilot comprises a specific set of modulation symbols that is subjected to spatial processing prior to transmission.

10. The apparatus of claim 8, wherein the MIMO communication system supports one or more of a single-input multiple-output (SIMO) transmission mode, a diversity transmission mode, a beam-steering transmission mode, a beam-forming transmission mode, a non-steered spatial multiplexing transmission mode, a multi-user spatial multiplexing transmission mode, or a spatial multiplexing transmission mode.

11. The apparatus of claim 8, wherein the pilot transmission from each antenna is associated with a different orthogonal code.

12. The apparatus of claim 8, further comprising:

a controller operative to estimate a channel response of at least one eigenmode for the communicating entity based on the received steered pilot.

13. The apparatus of claim 12, wherein the controller is further operative to derive a matched filter based on the estimated channel response of the at least one eigenmode, wherein the matched filter is used for matched filtering of a data transmission received via the at least one eigenmode from the communication entity.

14. The apparatus of claim 8, wherein the steered pilot is transmitted at full transmit power from a plurality of antennas at the communicating entity.

15. A non-transitory computer-readable medium for use in a wireless multiple-input multiple-output (MIMO) communication system, having a set of instructions stored thereon, the set of instructions being executable by one or more processors to perform the steps of:

transmitting a MIMO pilot on a forward channel from a plurality of antennas and on a first communication link via a plurality of transmission channels, wherein the MIMO pilot comprises a plurality of pilot transmissions sent from the plurality of antennas, and wherein the pilot transmission from each antenna is configured to be identifiable by a communicating entity receiving the MIMO pilot; and

receiving a steered pilot on a reverse channel via a plurality of eigenmodes of a second communication link from the communicating entity, wherein at least some of the plurality of eigenmodes are used for data transmission, and wherein the steered pilot is generated based on the MIMO pilot and a channel response matrix for the plurality of transmission channels.

16. The computer-readable medium of claim 15, wherein the steered pilot comprises a specific set of modulation symbols that is subjected to spatial processing prior to transmission.

17. The computer-readable medium of claim 15, wherein the MIMO communication system supports one or more of a single-input multiple-output (SIMO) transmission mode, a diversity transmission mode, a beam-steering transmission mode, a beam-forming transmission mode, a non-steered spatial multiplexing transmission mode, a multi-user spatial multiplexing transmission mode, and a spatial multiplexing transmission mode.

18. The computer-readable medium of claim 15, wherein the pilot transmission from each antenna is associated with a different orthogonal code.

19. The computer-readable medium of claim 15, further comprising instructions for:

estimating a channel response of at least one eigenmode for the communicating entity based on the received steered pilot.

20. The computer-readable medium of claim 19, further comprising instructions for:

deriving a matched filter based on the estimated channel response of the at least one eigenmode, wherein the matched filter is used for matched filtering of a data transmission received via the at least one eigenmode from the communication entity.