Full frequency reuse with nonorthogonal multiple access (NOMA) in heterogeneous networks (HetNets) can promisingly satisfy the fast-growing wireless transmission requirements, as the data of different users can be simultaneously delivered over the same frequency band. In HetNets, the transmissions from a micro base station (BS) to its cell-edge users often suffer from strong interference from the macro BS, which severely degrades the communication quality. The macro BS and the micro BS can transmit simultaneously to a common far-user using the distributed Alamouti coding technique to improve the communication robustness. Meanwhile, each BS also transmits data to a near-user using the NOMA protocol. The common far-user adopts the maximal ratio combining (MRC) technique to decode its desired data by treating the data of near users as interference. Each near-user decodes the data of far-user using the MRC technique and cancels it to decode its own data by treating the remaining undesired data as interference. Numerical results show that the Alamouti coding based NOMA transmission can greatly improve the throughput of HetNets.

中文翻译：

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具有分布式 Alamouti 空时编码的异构非正交多址

异构网络（HetNets）中非正交多址（NOMA）的全频率复用可以很好地满足快速增长的无线传输需求，因为不同用户的数据可以在同一频段上同时传输。在 HetNets 中，从微基站 (BS) 到其小区边缘用户的传输经常受到宏基站的强烈干扰，这严重降低了通信质量。宏基站和微基站可以使用分布式Alamouti编码技术同时向公共远端用户传输，以提高通信鲁棒性。同时，每个BS也使用NOMA协议向附近用户传输数据。普通远方用户采用最大比合并（MRC）技术，将近方用户的数据视为干扰来解码自己想要的数据。每个近用户使用 MRC 技术解码远用户的数据，并通过将剩余的不想要的数据视为干扰来取消它以解码自己的数据。数值结果表明，基于 Alamouti 编码的 NOMA 传输可以大大提高 HetNets 的吞吐量。