Cooperative Asynchronous Multichannel MAC: Design, Analysis, and Implementation

[nizar mayyeri]

Cooperative Asynchronous Multichannel MAC: Design, Analysis, and Implementation
Luo, T. Motani, M. Srinivasan, V. Nat. Univ. of Singapore, Singapore;
This paper appears in: Mobile Computing, IEE Transactions on Publication

Abstract
Medium access control (MAC) protocols have been studied under different contexts for decades. In decentralized contexts, transmitter-receiver pairs make independent decisions, which are often suboptimal due to insufficient knowledge about the communication environment. In this paper, we introduce distributed information sharing (DISH), which is a distributed flavor of control-plane cooperation, as a new approach to wireless protocol design. The basic idea is to allow nodes to share control information with each other such that nodes can make more informed decisions in communication. This notion of control-plane cooperation augments the conventional understanding of cooperation, which sits at the data plane as a data relaying mechanism. In a multichannel network, DISH allows neighboring nodes to notify transmitter-receiver pairs of channel conflicts and deaf terminals to prevent collisions and retransmissions. Based on this, we design a single-radio cooperative asynchronous multichannel MAC protocol called CAM-MAC. For illustration and evaluation purposes, we choose a specific set of parameters for CAM-MAC First, our analysis shows that its throughput upper bound is 91 percent of the system bandwidth and our simulations show that it actually achieves a throughput of 96 percent of the upper bound. Second, our analysis shows that CAM-MAC can saturate 15 channels at maximum and our simulations show that it saturates 14.2 channels on average, which indicates that, although CAM-MAC uses a control channel, it does not realistically suffer from control channel bottleneck. Third, we compare CAM-MAC with its noncooperative version called UNCOOP, and observe a throughput ratio of 2.81 and 1.70 in single-hop and multihop networks, respectively. This demonstrates the value of cooperation. Fourth, we compare CAM-MAC with three recent multichannel MAC protocols, MMAC, SSCH, and AMCP, and find that CAM-MAC significantly outperforms all of them. Finally, we implement CAM-MAC and UNC- - OOP on commercial off-the-shelf hardware and share lessons learned in the implementation. The experimental results confirm the viability of CAM-MAC and the idea of DISH.

[rajudeen]

MAC protocols have been studied under different contexts for decades. In decentralized MAC protocols, transmitter-receiver pairs make independent decisions, which are often sub-optimal due to insufficient knowledge about the communication environment. In this paper, we introduce control-plane cooperation at the MAC layer, where neighboring nodes share control information with transmitter-receiver pairs to aid them in making more informed decisions. This augments conventional cooperation, which sits at the data plane where intermediate nodes help relay data for other nodes. In a multi-channel environment, control-plane cooperation enables neighboring nodes to notify transmitter-receiver pairs of channel conflicts and deaf terminals to prevent collisions and retransmissions. Accordingly, we design a cooperative asynchronous multi-channel MAC protocol called CAM-MAC, which uses a single transceiver and is fully asynchronous. We evaluate CAM-MAC from both theoretical and practical perspectives, and show that it closely approaches system capacity and does not realistically suffer from control channel bottleneck. We compare CAM-MAC with its non-cooperative version, UNCOOP, and three recent multi-channel MAC protocols, MMAC, SSCH and AMCP. The results show that CAM-MAC significantly outperforms all of them. We also implement CAM-MAC and UNCOOP on commercial off-the-shelf hardware. The experimental results confirm the viability of CAM-MAC and the cooperation idea.