MIMO WLAN SYSTEM

• US 20080285670A1
• Filed: 07/15/2008
• 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 8,462,643 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 accessing a wireless multiple-access multiple-input multiple-output (MIMO) communication system, comprising:

receiving system information via a first transport channel on a downlink;

transmitting an access request via a second transport channel on an uplink, wherein the access request is transmitted based on the received system information;

monitoring a third transport channel on the downlink for an acknowledgment of the transmitted access request; and

repeating the receiving, transmitting, and monitoring if the acknowledgment is not received within a predetermined time period.

2. The method of claim 1, wherein the monitoring the third transport channel includes

monitoring an acknowledgment bit in the first transport channel, and

processing the third transport channel for the acknowledgment if the acknowledgment bit is set.

3. The method of claim 1, wherein a plurality of access requests are transmitted.

4. The method of claim 3, wherein the plurality of access requests are transmitted at successively lower rates.

5. The method of claim 3, further comprising:

waiting a pseudo-random period of time prior to transmitting a next access request among the plurality of access requests.

6. The method of claim 3, further comprising:

transmitting a steered pilot along with the access request on the second transport channel, the steered pilot being sent on at least one eigenmode of a MIMO channel for the uplink.

7. The method of claim 1, wherein the system information indicates a time interval in which transmission of access requests is allowed, and wherein the access request is transmitted within the time interval.

8. The method of claim 1, wherein the system information indicates a particular number of slots in which transmission of access requests is allowed, and wherein the access request identifies a specific slot in which the access request is transmitted.

9. The method of claim 8, wherein the slots have a time duration configurable by the system.

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

a receive data processor operative to receive system information via a first transport channel on a downlink;

a transmit data processor operative to process an access request for transmission via a second transport channel on an uplink, wherein the access request is transmitted based on the received system information;

a controller operative to monitor a third transport channel on the downlink for an acknowledgment of the transmitted access request, and

wherein the receive data processor is operative to receive updated system information, the transmit data processor operative to process another access request, and the controller operative to monitor the third transport channel if the acknowledgment is not received within a predetermined time period.

11. The apparatus of claim 10, wherein the controller is operative to monitor an acknowledgment bit in the first transport channel and to direct the receive data processor to process the third transport channel for the acknowledgment if the acknowledgment bit is set.

12. The apparatus of claim 10, wherein a plurality of access requests are transmitted.

13. The apparatus of claim 12, wherein the plurality of access requests are transmitted at successively lower rates.

14. The apparatus of claim 12, wherein the controller is operative to wait a pseudo-random period of time prior to initiating transmission of a next access request among the plurality of access requests.

15. The apparatus of claim 12, further comprising:

a transmit spatial processor operative to transmit a steered pilot along with the access request on the second transport channel, the steered pilot being sent on at least one eigenmode of a MIMO channel for the uplink.

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

means for receiving system information via a first transport channel on a downlink;

means for transmitting an access request via a second transport channel on an uplink, wherein the access request is transmitted based on the received system information;

means for monitoring a third transport channel on the downlink for an acknowledgment of the transmitted access request; and

means for repeating the receiving, transmitting, and monitoring if the acknowledgment is not received within a predetermined time period.

17. The apparatus of claim 16, wherein the means for monitoring the third transport channel includes

means for monitoring an acknowledgment bit in the first transport channel, and

means for processing the third transport channel for the acknowledgment if the acknowledgment bit is set.

18. The apparatus of claim 16, wherein a plurality of access requests are transmitted.

19. The apparatus of claim 18, wherein the plurality of access requests are transmitted at successively lower rates.

20. The apparatus of claim 18, further comprising:

means for waiting a pseudo-random period of time prior to transmitting a next access request among the plurality of access requests.

21. The apparatus of claim 18, further comprising:

means for transmitting a steered pilot along with the access request on the second transport channel, the steered pilot being sent on at least one eigenmode of a MIMO channel for the uplink.