Wireless Index Coded Transmission by Spatial Multiplexing With Multiple Antennas
Kyungrak Son, Jung Hoon Lee, Wan Choi · IEEE Transactions on Vehicular Technology · 2021
Index coding, a.k.a. coded multicasting, is one of the promising transmission schemes that can reduce the number of transmissions by leveraging the stored data in the users' memory. With multiple antennas, index coding gain can be further multiplied by spatially multiplexing but joint design of index code and beamforming has not been addressed well in literature. This paper figures out the gain of spatially multiplexed index code by jointly designing the multicast beamformer and index code. Since the optimal joint design problem itself is NP-hard, we take a two-step approach. At the first step, for an arbitrary index code, conjugate gradient-based multi-group multicast beamforming is designed. At the second step, the index code minimizing the total transmission time is selected. Our simulation results exhibit a substantial gain of spatially multiplexed index code by the proposed scheme.