Method and apparatus for determining receive diversity in mobile station

#The present invention relates generally to the field of communications, and more specifically, to communications using a receive diversity technique.

#The communication channel between a transmitter and a receiver is susceptible to noise, interference, and multipath. Multiple antennas may be used at the receiving destination to enhance the received signal. A receiver chain for signals received at each antenna may be necessary. Therefore, multiple receiver chains may be necessary to exploit the signals received at multiple receive antennas. Use of multiple receiver chains increases the power consumption. A mobile station in a communication system may greatly benefit from receive diversity; however, mobile stations generally have limited battery power supply.

#In another aspect, transmit power level of a signal targeted for a mobile station may be at a lower level when the mobile station is using receive diversity. Processing a received channel may be accomplished using receive diversity by combining the received signals. When the signals are combined at the receiver, the effective carrier to noise ratio of the channel may be increased to a level above the minimum level required for processing the channel. As a result, the transmitter may transmit the signal at a lower power level without effecting the receive processing. As such, the transmitter may be able to transmit to a larger number of mobile stations. Use of receiver diversity at the mobile station thus increases the capacity of the communication system; however, use of receiver diversity increases the power consumption at the mobile station.

#The features, objects, and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters identify correspondingly throughout and wherein:

#FIG. 1 depicts a communication system capable of operating in accordance with various embodiments of the invention;

#FIG. 2 depicts a communication system receiver for receiving and decoding received data in accordance with various aspects of the invention;

#Various embodiments of the invention may be incorporated in a wireless communication system operating in accordance with the code division multiple access (CDMA) technique which has been disclosed and described in various standards published by the Telecommunication Industry Association (TIA) and other standards organizations. Such standards include the TIA/EIA-95 standard, TIA/EIA-IS-2000 standard, IMT-2000 standard, UMTS and WCDMA standard, all incorporated by reference herein. A system for communication of data is also detailed in the “TIA/EIA/IS-856 cdma2000 High Rate Packet Data Air Interface Specification,” incorporated by reference herein. A copy of the standards may be obtained by accessing the world wide web at the address: http://www.3gpp2.org, or by writing to TIA, Standards and Technology Department, 2500 Wilson Boulevard, Arlington, Va. 22201, United States of America. The standard generally identified as UMTS standard, incorporated by reference herein, may be obtained by contacting 3GPP Support Office, 650 Route des Lucioles-Sophia Antipolis, Valbonne-France.

#Generally stated, various aspects of the invention provide for efficient use of communication resources in a CDMA communication system. In accordance with at least one aspect of the invention, various conditions for using receive diversity are determined. The use of receive diversity is determined, most likely, for conditions that produces its beneficial features, such as system capacity to accommodate more users and preventing erroneous decoding of the received data, while minimizing the impact on battery life of the mobile station.

#One or more exemplary embodiments described herein are set forth in the context of a digital wireless communication system. While use within this context is advantageous, different embodiments of the invention may be incorporated in different environments or configurations. In general, the various systems described herein may be formed using software-controlled processors, integrated circuits, or discrete logic. The data, instructions, commands, information, signals, symbols, and chips that may be referenced throughout the application are advantageously represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or a combination thereof. In addition, the blocks shown in each block diagram may represent hardware or method steps.