在LTE蜂巢式網路下採用資源區塊複用的裝置對裝置通訊以實現兩階段群播的評估

隨著多媒體網路的發展，群播技術被視為有效的傳送相同資料給群組內多個成員的技術。然而在無線網路中，因為接收者無線通道的差異性，群播必須以最差的通道為考量來選用調變和編碼方式，限制了整體群播的吞吐量、進而造成時間上的延遲，因此需要更有效的群播方法被提出。本論文藉由組成裝置對裝置通訊(Device-to-Device Communication；D2D)的叢集(Cluster)，再利用D2D近距離的特性，探討兩階段群播對於改善群播效能的功效。本篇論文的特點之一在於允許D2D重複使用蜂巢式網路上行(Uplink)資源區塊(Resource Block；RB)，資源區塊的重複使用需滿足蜂巢式網路以及D2D通訊的訊號與干擾加雜訊比(Signal to Interference plus Noise Ratio；SINR)不低於預設的門檻值。本篇所提出的兩階段群播方法有三個步驟，首先藉由量測叢集成員與基地台之間的通道狀況，選出一個叢集頭；接著根據叢集成員與蜂巢式使用者之間的干擾情況，尋找每個叢集能重複使用的RB；並且使用匈牙利演算法，找出每一個叢集最適用的RB；最後，群播的進行是在第一階段由基地台傳至叢集頭，然後在第二階段由叢集頭再群播至所有的叢集成員。我們用軟體模擬比較兩階段群播與單一階段群播的效能，我們考慮叢集的大小及距離基地台的遠近對於效能(吞吐量、時間延遲、資源使用效率)的影響，模擬結果顯示兩階段群播在叢集離基地台較遠且叢集半徑較小的時候，其效能比一階段群播為佳。

關鍵字

蜂巢式網路；群播； D2D通訊；叢集；資源共用

並列摘要

With the booming of multimedia services, multicast has been considered as an efficient way to disseminate the same multimedia data simultaneously to all members in a group. However, due to the differences in wireless channel conditions experienced by multicast recipients and to ensure that the multicast is successfully received by all members, the multicast transmitter needs to choose a modulation and coding scheme (MCS) that allows the transmission to survive the worst channel condition, thus severely limiting the multicast throughput. Works have been done to address this problem. One of them is the D2D (device-to-device) assisted two-stage multicast. In this thesis, we propose a variation of the D2D-assisted two-stage multicast scheme that reuses CUE (cellular-network user equipment) resource blocks (RB) for the second-stage D2D communication. The reuse of RBs has to satisfy the QoS requirements for both CUE and DUE (D2D user equipment). There are three steps in our proposed two-stage multicast. First, a cluster head (CH) is elected by considering the channel gains between cluster (group) members and the basestation (eNodeB in LTE). Second, reusable RBs are identified and suitable CH power and MCS are calculated for every cluster by considering the interferences between cluster members and CUEs, and then the optimized RB allocation is solved by using the Hungarian algorithm. The third step is to execute the two-stage multicast, where the eNodeB transmits data to the CH in the first stage, and then CH multicasts with the above calculated power and MCS to all members in the second stage. We use simulations to compare the delay times between two-stage multicast and one-stage multicast by varying the cluster size and the distance between eNodeB and the cluster. We also evaluate the resource efficiency gained, and extra power consumed, by RB reuse. Our results show that two-stage multicast is better than one-stage multicast when the cluster is far away from the basestation and the cluster diameter is small.

並列關鍵字

cellular network ； multicast ； D2D communication ； cluster ； resource reuse

參考文獻

[3] 3GPP TS 36.321: “Evolved Universal Terrestrial Radio Access (E-UTRA); Medium Access Control (MAC) protocol specification (Release 12)”.

[4] 3GPP TS 36.211: “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical channels and modulation (Release 12)”.

[10] H. Yoon and J. Kim, “Collaborative streaming-based media content sharing in WiFi-enabled home networks,” IEEE Trans. Consumer Electron., vol. 56, no. 4, pp. 2191–2200, Nov. 2010.

[11] F. Hou, L. X. Cai, P. H. Ho, X. Shen, and J. Zhang, “A cooperative multicast scheduling scheme for multimedia services in IEEE 802.16 networks,” IEEE Trans. Wireless Commun., vol. 8, no. 3, pp. 1508–1519, Mar. 2009.

[12] A. Pyattaev, K. Johnsson, S. Andreev, and Y. Koucheryavy, “Proximity based data off-loading via network assisted device-to-device communications,” IEEE VTC-Spring, 2013.

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在LTE蜂巢式網路下採用資源區塊複用的裝置對裝置通訊以實現兩階段群播的評估

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