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.

中文翻译：

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通过多天线空间复用实现无线索引编码传输


索引编码，又名编码多播，是一种有前途的传输方案，它可以通过利用用户内存中存储的数据来减少传输次数。对于多个天线，索引编码增益可以通过空间复用进一步倍增，但索引编码和波束成形的联合设计在文献中尚未得到很好的解决。本文通过联合设计多播波束形成器和索引码，计算出空间复用索引码的增益。由于最优联合设计问题本身是 NP 难题，因此我们采用两步方法。第一步，针对任意索引码，设计基于共轭梯度的多组多播波束成形。第二步，选择使总传输时间最小化的索引码。我们的模拟结果表明，所提出的方案在空间复用索引码方面取得了显着的增益。