Channel measurement and performance of multicast beamforming in campus network

• Published in: International Conference on Wireless Communications and Signal Processing pp. 1 - 6
• Main Authors: Shimu Yang, Aghaeinezhadfirouzja, Saeid, Chen, Erkai, Meixia Tao
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.10.2016
• Subjects: Array signal processing; Channel estimation; channel measurement; channel state information (CSI); Frequency-domain analysis; Long Term Evolution; multicast beamforming; OFDM; Receivers; semi-definite relaxation (SDR); Signal to noise ratio
• ISSN: 2472-7628
• DOI: 10.1109/WCSP.2016.7752680

Multicast plays an important role in wireless networks to delivery a common message to multiple users simultaneously. Multicast beamforming can further boost the system performance by utilizing channel state information (CSI) at the base station (BS) equipped with multiple antennas. This paper provides a validation of multicast beamforming over actual channels measured in the Shanghai Jiao Tong University (SJTU) campus wireless network, a FDD LTE network. We first build a receiver prototype using USRP N210 and LabVIEW for channel measurement. A single base station with 4 antennas and 3 single-antenna receivers are considered. Based on the measured actual CSI, we then evaluate the performance of multicast beamforming under the quality of service (QoS) problem formulation, which is to minimize the transmit power consumption subject to an individual Signal to Noise Ratio (SNR) constraint for each user receiver. The Semi-Definite Relaxation (SDR) approach is adopted to find an solution close to primitive solution. Experimental results demonstrate that multicast transmission using a single beamformer provides significant power gain over unicast transmission with multiple beamformers under the same QoS constraints in our considered campus network.