High-Resolution MIMO Channel Sounding Algorithm Design and Instrumental Verification in LTE Uplink Transmission

• Main Authors: Chien-Min Chen, 陳建旻
• Other Authors: Jeng-Kuang Hwang
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/48490058036062211876

碩士 === 元智大學 === 通訊工程學系 === 102 === A high-resolution channel sounding (HRCS) algorithm which is able to accurately estimate the multipath channel with fractional delays is proposed in this thesis. In the proposed algorithm, we use the LTE uplink sounding reference signal under an OFDM system with shaping filter in the front end. To begin with, we introduce the time- and frequency-domain multipath channel model. In term of the superimposed sinusoidal property of the channel frequency response, we can exploit a high-resolution sinusoidal parameter estimation method called ANPA (alternating notch periodogram algorithm) to catch the multipath channel parameters, including path delays, path attenuation, and the number of multipath. However, since the composite channel response includes both the TX and RX filters, the RX filter’s output noise will be colored noise under T/2 sampling, which is required to satisfy the sampling theorem. In such a case, the ANPA will suffer performance degradation. Hence, we deliberately change the conventional SRRC/SRRC T/R filter to the RC/LPF configuration, such as to restore the AWGN noise property at the RX filter output. Furthermore, the ANPA should be modified to take into account the RC response within the composite channel frequency response now. In this way, we could accurately sound the multipath channel with high-resolution fractional delay estimate. Furthermore, we exploit the CAZAC property with cyclic shifts of the SRS sequence, and extend the above SISO High- Resolution Chanel Sounding (HRCS) Algorithm to the MIMO case. Finally, we use many instruments to verify the proposed algorithms. The vector signal generator is used to transmit the SRS, which then pass through a channel emulator used to simulate the multipath channel. At last, the SISO/MIMO received signal is obtained by a multi-channel receiver consisting of RF mixer, synthesizer, and digital oscilloscope for implementing low-IF and sub-Nyquist bandpass sampling. By the experimental setting, the proposed HRCS algorithm is verified for sounding a variety of multipath channels, both time variant and time invariant, and both SISO and MIMO.