Channel sounding for improved system performance

Abstract

A transmitter generates and transmits a low rate signal to its intended receiver. Upon receiving the low rate signal, the intended receiver generates and transmits a channel sounding response (CSR), said CSR being a short burst having a predefined transmit format and carrying predetermined information. The transmitter then analyzes the CSR and determines uplink channel response, estimates downlink channel response, and determines appropriate transmit parameter settings based on the analysis and downlink response estimate. Adjustment of the transmit parameters can be made in either the MAC or PHY layer or in a combination of both. After adjusting its transmit parameters and modulating sub-carriers with user-data according to the determined transmit settings, the transmitter transmits the user-data to the receiver on a preferred portion of bandwidth. In a preferred embodiment, the transmitter also generates and transmits a transmit format control (TFC) signal containing the determined transmit parameter settings, including sub-carrier modulation information, to the receiver.

1 - 16 . (canceled) 
     
     
         17 . A method for improving system performance in a Multiple-Input, Multiple-Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) wireless communication system comprising:
 (a) monitoring CSR signals transmitted between a transmitter and a receiver;   (b) assessing channel conditions of a communication link between the transmitter and the receiver;   (c) maintaining a history of said channel conditions;   (d) adjusting transmit parameters based on the channel history; and   (e) communicating with the transmitter and receiver utilizing the adjusted transmit parameters.