Coop80211: Implementation and evaluation of a SoftMAC-based Linux kernel module for cooperative retransmission

This paper presents a portable and hardware-independent data-link layer design that adds cooperative retransmission support to the Linux kernel wireless SoftMAC implementation (mac80211). With cooperative retransmission, a unicast packet that is not acknowledged by its intended destination node can be retransmitted by a third node in the vicinity of the source and destination, rather than by the original source itself, if the cooperating node overhears the packet successfully and has a better link to the destination. Unlike prior realizations of MAC-layer cooperation schemes, our implementation is entirely hardware-independent and transparent, requiring no modification of existing wireless drivers or upper-layer software. We evaluate the cooperative kernel module on the ORBIT wireless testbed platform and present a range of experimental results that demonstrate the significant improvements in the throughput and reliability that can be achieved by its usage.