DCMA: A Label Switching MAC for Efficient Packet Forwarding in Multi-Hop Wireless Networks

This paper addresses the problem of efficient packet forwarding in a multi-hop, wireless “mesh” network. We first explain how the packet forwarding operation in the wireless broadcast medium differs from that of a router in wired network, which typically switches packets across multiple network interfaces. In a wireless mesh network on the other hand, any node with a single wireless network interface card can operate as a router or a forwarding node, since it can receive a packet from a neighboring node, do a route lookup based on the packet’s destination IP address and then transmit the packet to another neighboring node using the same wireless interface. This paper introduces an efficient interface contained forwarding (ICF) architecture for a “wireless router”, i.e. a forwarding node with a single wireless NIC in a multi-hop wireless network that allows a packet to be forwarded entirely within the network interface card of the forwarding node without requiring per-packet intervention by the node’s CPU. To effectively forward packets in a pipelined fashion without incurring the 802.11-related overheads of multiple independent channel accesses, we specify a slightly modified version of the 802.11 MAC, called DCMA, which preserves all the basic distributed medium access functions of 802.11. DCMA’s primary innovation lies in the use of MPLS-like labels in the control packets, and in the use of a combined ACK/RTS packet to combine upstream packet reception acknowledgment with downstream channel access. Using extensive simulations with two different topologies: chain and grid, we compare the performance of DCMA with 802.11 DCF MAC with respect to throughput and latency.

By: Arup Acharya, Sachin Ganu, Archan Misra

Published in: RC23210 in 2004


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