| Summary: | 碩士 === 國立中正大學 === 通訊工程研究所 === 104 === 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.
|
|---|
