Title :
Performance of analog feedback in closed-loop transmit diversity systems
Author :
Chiu, Eddy ; Ho, Paul ; Kim, Jae Hyung
Author_Institution :
Sch. of Eng. Sci., Simon Fraser Univ., Burnaby, BC
Abstract :
This paper is concerned with the efficient transmission of channel state information (CSI) in the uplink, and data in the downlink, of a closed-loop transmit diversity system. Two ideas were explored: 1) the employment of analog CSI feedback whereby estimates of the downlink complex gains were fed back periodically to the base-station at a rate of only 1 analog symbol per estimate per frame, and 2) the use of position dependent modulation (PDM) to counter the signal-to-noise ratio variation across a downlink data frame. Simulation results indicated that as far as the bit-error-rate (BER) is concerned, analog feedback is superior to digital feedback because it does not experience unrecoverable quantization errors in the feedback channel estimates. The simulation also indicated that at a given target BER, PDM can attain a substantially higher throughput than fixed modulation
Keywords :
channel estimation; closed loop systems; diversity reception; error statistics; feedback; modulation; BER; analog CSI feedback; base station; bit error rate; channel state information; closed-loop transmit diversity systems; digital feedback; downlink complex gains; downlink data frame; feedback channel estimates; fixed modulation; position dependent modulation; signal-to-noise ratio variation; unrecoverable quantization errors; Array signal processing; Bit error rate; Channel state information; Data engineering; Delay; Downlink; Feedback; Quantization; Throughput; Transmitting antennas;
Conference_Titel :
Wireless Communications and Networking Conference, 2006. WCNC 2006. IEEE
Conference_Location :
Las Vegas, NV
Print_ISBN :
1-4244-0269-7
Electronic_ISBN :
1525-3511
DOI :
10.1109/WCNC.2006.1696461