MIMO WLAN SYSTEM

• US 20080285669A1
• Filed: 04/30/2008
• Published: 11/20/2008
• Est. Priority Date: 10/25/2002
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Howard, Steven J., Ketchum, John W., Walton, J. Rodney, Wallace, Mark S.
• Granted Patent: US 9,240,871 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• 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 performing channel estimation in a wireless multiple-input multiple-output (MIMO) communication system, comprising:

receiving a steered pilot via at least one eigenmode of an uplink from a user terminal; and

estimating a channel response of the at least one eigenmode of the uplink for the user terminal based on the received steered pilot.

2. The method of claim 1, further comprising:

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

3. The method of claim 1, further comprising:

estimating a channel response of at least one eigenmode of a downlink for the user terminal based on the received steered pilot.

4. The method of claim 3, further comprising:

deriving at least one steering vector based on the estimated channel response of the at least one eigenmode of the downlink, wherein the at least one steering vector is used for data transmission on the at least one eigenmode of the downlink to the user terminal.

5. The method of claim 4, wherein the steered pilot is received via a plurality of eigenmodes of the uplink, wherein the channel response of a plurality of eigenmode of the downlink for the user terminal is estimated based on the received steered pilot, and wherein a plurality of steering vectors are derived based on the estimated channel response of the plurality of eigenmodes of the downlink.

6. The method of claim 5, wherein the plurality of steering vectors are derived to be orthogonal to one another.

7. An apparatus in a wireless multiple-input multiple-output (MIMO) communication system, comprising:

a receive spatial processor operative to receive a steered pilot via at least one eigenmode of an uplink from a user terminal; and

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

8. The apparatus of claim 7, wherein the controller is further operative to derive a matched filter based on the estimated channel response of the at least one eigenmode of the uplink, wherein the matched filter is used for matched filtering of a data transmission received via the at least one eigenmode of the uplink from the user terminal.

9. The apparatus of claim 7, wherein the controller is further operative to estimate a channel response of at least one eigenmode of a downlink for the user terminal based on the received steered pilot.

10. The apparatus of claim 9, wherein the controller is further operative to derive at least one steering vector based on the estimated channel response of the at least one eigenmode of the downlink, wherein the at least one steering vector is used for data transmission on the at least one eigenmode of the downlink to the user terminal.

11. An apparatus in a wireless multiple-input multiple-output (MIMO) communication system, comprising:

means for receiving a steered pilot via at least one eigenmode of an uplink from a user terminal; and

means for estimating a channel response of the at least one eigenmode of the uplink for the user terminal based on the received steered pilot.

12. The apparatus of claim 11, further comprising:

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

13. The apparatus of claim 11, further comprising:

means for estimating a channel response of at least one eigenmode of a downlink for the user terminal based on the received steered pilot.

14. The apparatus of claim 13, further comprising:

means for deriving at least one steering vector based on the estimated channel response of the at least one eigenmode of the downlink, wherein the at least one steering vector is used for data transmission on the at least one eigenmode of the downlink to the user terminal.