基于集中式时分多址的MAC协议

MAC protocol based on centralized time division multiple access

由于节点的高速移动、网络拓扑的动态变化,设计车联网(VANETs)的媒介接入控制(MAC)协议仍存在挑战。为此,提出基于集中式时分多址(TDMA)的MAC协议(C-TDMA-MAC)。C-TDMA-MAC协议选择路边设备(RSUs)作为中心协调者,并由它们向覆盖范围内的车辆分配、协调时隙。C-TDMA-MAC利用时隙复用概念确保两个RSUs覆盖的相邻区域的车辆具有无碰撞的时隙分配。信道时间划分不同帧,每个帧进一步划分为两个时隙集,这些时隙集分配给两个相邻RSUs的移动车辆,降低了RSUs间的干扰。实验数据表明,与VeMAC和Ad Hoc MAC协议相比,提出的C-TDMA-MAC协议能有效地降低传输碰撞和开销。

It is a challenge to design the medium access control(MAC)protocol in vehicular Ad Hoc networks(VANETs)due to the fast movement of nodes and dynamic variation of network topology.Therefore,a MAC protocol based on centralized time division multiple access(TDMA)is proposed,which is denoted as C-TDMA-MAC.The road side units(RSUs)are used as the central coordinators of C-TDMA-MAC protocol to allocate and coordinate the time slot of the vehicles within coverage range.The time slot reuse is used in C-TDMA-MAC protocol to ensure the collisionless time slot allocation of the vehicles in the adjacent areas covered by two RSUs.The channel time is divided into different frames,and each frame is further divided into two time slot sets.The time slot sets are allocated to the moving vehicles in the adjacent areas covered by two RSUs to reduce the interference between RSUs.The experimental results show that,in comparison with VeMAC and Ad Hoc MAC protocols,the C-TDMA-MAC protocol can reduce the transmission collision and overhead more effectively.