Title :
A novel CQI-assisted sounding design for TDD LTE-Advanced system
Author :
Zhou, Baolong ; Jiang, Lingge ; Chen, He ; Zhao, Shengjie
Author_Institution :
Dept. of Electron. Eng., Shanghai Jiao Tong Univ., Shanghai, China
Abstract :
In the long term evolution (LTE) time division duplex (TDD) systems, base stations use uplink sounding reference signals (SRSs) to estimate downlink channel state information (CSI) for downlink beamforming transmissions. Because SRSs sent by up to 8 users are multiplexed on the same time-frequency resources, there exist mutual interferences among these SRSs over fading channels. Thus this scheme inevitably impacts the estimation accuracy of CSI and thereby degrades the beamforming performance. In this paper, we propose a novel sounding scheme to improve the quality of CSI, in which according to the CQIs (channel quality indications) periodically reported by each user and the bandwidth requirement of each user, BS dynamically schedules each user to send SRSs only on the requisite bandwidth with best CQIs instead of on full bandwidth or specified sub-bandwidth as in the current LTE TDD systems. Simulations show that the proposed scheme obtains much better estimation accuracy than the current scheme for various frequency-selective and/or time-selective fading channels, and is robust to frequency selective channels. Therefore the proposed scheme is applicable to the uplink SRS design in LTE-Advanced and other MIMO-OFDM TDD systems.
Keywords :
Long Term Evolution; MIMO communication; OFDM modulation; array signal processing; channel estimation; estimation theory; fading channels; radiofrequency interference; scheduling; time division multiplexing; time-frequency analysis; BS; CQI-assisted sounding design; CSI; Long Term Evolution; MIMO-OFDM TDD system; TDD LTE-Advanced system; base station; channel quality indication; downlink beamforming transmission; downlink channel state information estimation; frequency-selective fading channel; multiplexing; mutual interference; time division duplex system; time-frequency resource; time-selective fading channel; uplink SRS design; uplink sounding reference signal; Array signal processing; Bandwidth; Channel estimation; Delay; Frequency domain analysis; Time domain analysis; Long Term Evolution (LTE); channel estimation error; sounding; time division duplex (TDD);
Conference_Titel :
Communications (ICC), 2012 IEEE International Conference on
Conference_Location :
Ottawa, ON
Print_ISBN :
978-1-4577-2052-9
Electronic_ISBN :
1550-3607
DOI :
10.1109/ICC.2012.6364280