A label-switching packet forwarding architecture for multi-hop wireless LANs

Abstract

A router in wired network typically requires multiple network interfaces to act as a router or a forwarding node. In an ad-hoc multi-hop wireless network on the other hand, any node with a 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 investigates a combined medium access and next-hop address lookup based on fixed length labels (instead of IP addresses), which allows the entire packet forwarding operation to be executed within the wireless NIC without the intervention of the host protocol stack. Medium access schemes to date, such as IEEE 802.11, have been designed implicitly for either receiving or transmitting a packet, but not for a forwarding operation, i.e. receiving a packet from an upstream node and then immediately transmitting the packet to a downstream node as an atomic channel access operation. This paper proposes a MAC protocol for packet forwarding in multihop wireless networks. The proposed protocol builds on the IEEE 802.11 DCF MAC using RTS/CTS and uses MPLS like labels in the control packets (RTS/CTS) to allow the forwarding node to determine the next hop node while contending for the channel. The throughput of this protocol is compared with 802.11 DCF MAC through simulation.