System, method and apparatus for transmit diversity control based on variations in propagation path

Abstract

A method and apparatus for applications of identification of variations of propagation path to transmit diversity control. Transmit diversity parameters may be modified according to detected dynamics, which may, for example, be related to changes in actual propagation and network conditions. Such dynamics may be referred to as mobility parameters. Mobility parameters may apply to variability in a propagation path due to any conditions. Determination of a mobility parameter may be conducted using one or more of multiple parameters available to the mobile terminal. Such feedback information indication, which is related to the propagation path conditions, may be provided to the apparatus, which would attempt to find a more desired mode of operation, which may lead to reduction in power and the improvement of the quality of transmission.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation in part of U.S. patent application Ser. No. 11 / 712,569, entitled “Method, System and Apparatus for Estimation of Propagation Path Variability of a Transmit Diversity Channel” and filed Mar. 1, 2007, and also claims benefit of U.S. Provisional Patent Application Ser. No. 60 / 904,198, entitled “Applications of Identification of Variations in Propagation Path to Transmit Diversity Control” and filed Mar. 1, 2007, the entirety of all of which are incorporated by reference herein.FIELD OF THE INVENTION[0002]The present invention relates generally to the field of wireless communications, and more specifically to methods, systems and apparatus for transmit diversity control related to propagation path conditions.BACKGROUND OF THE INVENTION[0003]Wireless transmission systems may use transmit diversity, whereby signals are transmitted to a receiver using a plurality of transmit antennas. A receiving communication ...

AI Technical Summary

Benefits of technology

[0005]When propagation conditions are stable or vary slowly, small changes of parameters around values previously defined may provide good performance and more stable operation and maximize benefits of transmit diversity control. In a dynamic environment, such as when a mobile terminal may be moving or other objects in the vicinity may cause variations of the propagation path between a transmitter and a receiver, transmit diversity control may achieve improved performance by, for example, allowing a larger change in a transmit diversity control algorithm parameter. A transmit diversity parameter may be, for example, a step size in a phase difference between signals transmitted on the respective plurality of antennas, or may be a smaller interval between changes in parameters. A faster rate of change of a transmit diversity parameter may allow faster adaptation of a transmit diversity control parameter to a varying propagation condition.

[0008]The value of a mobility parameter may be determined by observing variations in power in the transmitted or received signals. For example, one method according to embodiments of the invention may detect a difference in power within a time window to detect changes in dynamics of propagation path. In some embodiments of the invention, one or both of phase difference and power ratio may be used to compute the value of the mobility parameter, which in turn may be used to provide flexibility and / or adaptability in cases where the channel amplitude and phase vary at different rates. For example, a phase-based mobility parameter may be used to adjust the transmit diversity phase difference step size and / or a power-based mobility parameter may be used to adjust the transmit diversity power ratio step size.

[0009]Certain embodiments of the invention may provide one or more technical advantages. Implementation of the transmit diversity systems embodying the present invention may provide one or more technical advantages, including, for example, optimizing transmit signal power, improving effectiveness of transmit diversity control, improving power consumption at the transmitting communication device by lowering power needed to transmit signals, improving wireless communication system capacity by reducing interference among wireless communication users, improving transmission efficiency by selecting optimal algorithms and parameters that will mitigate fading and improve beam-forming, and / or improving performance in other ways as a result of implementation of embodiments of the present invention.

Problems solved by technology

The transmitted signals may propagate along different paths and may reach the receiving communication device with different phases that may destructively interfere.

The received signal quality may change at a receiver that may be attempting to detect a transmission from a mobile terminal, as well as a noise level created by a wireless terminal transmission in base stations attempting to detect signals from other wireless terminals.

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