LTE-Advanced網路中具QoS感知之D2D模式選擇

Abstract

在裝置對裝置(Device-to-Device,D2D)的議題中，模式選擇(Mode Selection)被視為是用來改善D2D干擾的一項技術。然而，現今關於模式選擇的文獻，大多聚焦在節能的議題上，較少文獻在研究增進D2D頻譜使用率，而頻譜使用效益仍有改善空間。因此，在滿足服務品質(Quality of Service, QoS)的前提下，我們提出一個服務品質感知的模式選擇( QoS Aware Mode Selection，QAMS) 機制，其目的是根據現有UE分佈情形，能夠在吞吐量( throughput) 不輸給傳統的三種模式選擇下，盡可能的提升頻譜使用效率。QAMS將傳統三種模式選擇的頻譜分配方式結合成一種新的以中頻譜分配方式。在QAMS方法中，頻譜分配保有傳統三種模式選擇的特性，將所有頻譜分成三個區塊，每個區塊對應到一種傳統的模式選擇功能，我們再根據QoS來推算出最適合目前所有UE分佈情形的頻譜分配比率。實驗結果顯示，在七個細胞的模擬環境下，在吞吐量方面，QAMS與複用模式( reuse mode)相比，有優於14%的表現，和專屬模式(dedicated mode)相比，贏4%，和中繼模式( relay mode)相比，有優於8%的表現。在頻譜使用率方面， QAMS與專屬模式相比，優於34%的表現，與中繼模式相比，優於34%的表現。

Mode Selection is considered a technique to improve D2D interference. In today`s mode selection literature, there are few discussions about increasing spectrum utilization. In order to improve spectrum usage effectively, we propose a Quality of Service Aware Mode Selection (QAMS) mechanism to combine the spectrum allocation methods of the traditional three modes. The goal is to improve spectrum efficiency as much as possible based on the existing UE distribution scenario with throughput constantly higher than the traditional three modes. QAMS method combines characteristics of a conventional three selection modes. The spectrum is divided into three blocks and each block corresponds to a conventional mode selection function. Based on the QoS, we derive the spectrum allocation ratio that is the most suitable for all current UE distribution scenarios. Our simulation environment is based on seven cells. As the number of cellular UEs and D2D UEs increases gradually, in terms of throughput, QAMS has better performance than 14% compared with reuse mode, and wins 4% compared with dedicated mode, which is better than 8 % in relay mode. In terms of spectrum usage, QAMS outperforms the dedicated mode by 34%, and is better than the relay mode by 34%.