以多輸入多輸出實現多用戶裝置對裝置網路的干擾控制

Abstract

裝置對裝置的通訊架構是目前次世代網路的熱門議題之一。藉由兩個裝置的直接通訊，我們可以減少電信網路中基地台的過載問題，3GPP 也積極在制定裝置對裝置通訊的標準架構。由於裝置對裝置傳輸與傳統的基地台傳輸（包含上行和下行）都使用同樣的基地台資源，裝置對裝置通訊最大的難題在於干擾。目前常見的抗干擾機制，大多是將兩種不同的傳輸放在不同的時間或是載波；或是藉由壓低裝置對裝置傳輸的功率，避免影響傳統傳輸的使用者。在我的研究中，我提出一個運用目前手持裝置具備的多天線，以多輸出多輸入的技術，來消除兩種傳輸機制之間的干擾。

Device-to-device (D2D) communications is an emerging service model that is currently under standardization by 3GPP. Although D2D offloading has a great potential to relieve increasingly congested cellular networks, its benefits come at a cost, namely interference. Most of the prevailing D2D designs conservatively avoid interference via either spectrum resource allocation or power control. These works however do not exploit the spatial degrees of freedom (DoF) inherently supported by a multi-antenna device. In this work, we present MD2D, a multiuser D2D system that embraces concurrent D2D transmissions, while leveraging MIMO techniques to actively eliminate interference across D2D pairs. MD2D has a systematic methodology that checks whether the antenna combination in a D2D network is capable of eliminating cross-pair interference, and thus ensuring interference-free concurrent transmissions. If the interference can be eliminated, then MD2D applies a bucket-based DoF assignment algorithm to determine an effective antenna usage configuration that handles the interference. We evaluate our design via testbed experiments and simulations. The results show that, as compared to the traditional interference avoidance scheme, MD2D improves the throughput by 87.39% and 236.02% in a three-pair testbed and in large-scale simulations, respectively.