Efficient signaling for closed-loop transmit diversity
AssigneeQUALCOMM Incorporated
InventorsMing-Chang Tsai, Ann Tsuey Jiuan Wu, Hailiang Cai
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Abstract
Techniques for encoding a phase adjustment for a feedback signal in a closed-loop transmit diversity system. In an aspect, codewords for the phase adjustments are chosen according to a variable-length prefix code. The prefix code aspect allows the codewords to be transmitted in sequence on the feedback channel without being separated by “commas” or demarcation symbols. The variable-length aspect provides a variety of coarse and fine phase adjustment quantization step sizes to accommodate multiple different channel scenarios. In an aspect, the length of the codewords may be further optimized according to the Huffman encoding algorithm.
Claims34
An apparatus for transmitting information on a feedback channel, the apparatus comprising:
- a receiver configured to receive a signal on a primary channel;
- an update calculation module configured to determine an adjustment to be applied on the primary channel based on the received signal;
- an encode module configured to encode the adjustment to be applied using a variable-length prefix code;
- and
- a transmitter configured to transmit the encoded adjustment on the feedback channel.
An apparatus for receiving information on a feedback channel, the apparatus comprising:
- a transmitter configured to transmit first and second signals using first and second antennas, respectively, on a primary channel, the first and second signals having a relative phase difference;
- a receiver configured to receive an encoded phase adjustment signal on a feedback channel;
- a phase decode module configured to decode the encoded phase adjustment signal using a variable-length prefix code;
- and
- a phase control module configured to adjust the relative phase difference based on the decoded phase adjustment signal.
A method for transmitting information on a feedback channel, the method comprising:
- receiving a signal on a primary channel;
- determining an adjustment to be applied on the primary channel based on the received signal;
- encoding the adjustment to be applied using a variable-length prefix code;
- and
- transmitting the encoded adjustment on the feedback channel.
A method for receiving information on a feedback channel, the method comprising:
- transmitting first and second signals using first and second antennas, respectively, on a primary channel, the first and second signals having a relative phase difference;
- receiving an encoded phase adjustment signal on a feedback channel;
- decoding the encoded phase adjustment signal using a variable-length prefix code;
- and
- adjusting the relative phase difference based on the decoded phase adjustment signal.
An apparatus for transmitting information on a feedback channel, the apparatus comprising:
- means for receiving a signal on a primary channel;
- means for determining an adjustment to be applied on the primary channel based on the received signal;
- means for encoding the adjustment to be applied;
- and
- means for transmitting the encoded adjustment on the feedback channel.
A computer program product for transmitting information on a feedback channel, the product comprising:
- computer-readable medium comprising:
- code for causing a computer to receive a signal on a primary channel;
- code for causing a computer to determine an adjustment to be applied on the primary channel based on the received signal;
- code for causing a computer to encode the adjustment to be applied using a variable-length prefix code;
- and
- code for causing a computer to transmit the encoded adjustment on the feedback channel.
Dependencies are inferred from the claim text.