The Anti-Packets Can Increase the Achievable Throughput of a Wireless Multi-Hop Network, by Petar Popovski and Hiroyuki Yomo, of Aalborg University, ICC'06.
The idea is very simple, and it is one of the few applications that I have seen of the field of network coding, which may actually work. Surprisingly enough, the authors don't seem to know what network coding is. At least, they don't mention it.
This paper came at about the same time as the COPE paper from Dina Katabi's group at MIT which presents the same idea with a slightly different approach (COPE is more general). I would guess that, due to the MIT reputation and the publication forum, the citation count for COPE will outnumber the number of citations for this paper by a factor 100, even though both had the same idea at about the same time.
Assume a multi-hop wireless network with 3 nodes, A, B and C. A needs to send a packet AC to C, and C a packet CA to A (both packets of same length and errorless transmissions). The current way of doing it is in 4 time slot: 1-AC from A to B; 2-CA from C to B; 3-AC from B to C; 4-CA from B to A.
The idea of the paper is to combine 3 and 4, and to use the fact that since A and C both hear B, the last step can be: 3-B transmits ACA = XOR(AC,CA) to both B and A.
A, using ACA and AC, can recover CA, and similarly C can recover AC. The gain in bandwidth is 33%.
The throughput can be doubled in an analog manner: if A and C transmit at the same time (slot 1), then B hears a signal composed of both A and C components, A+C. Assuming B hears them both with the same power, then it can just replay the signal it heared in slot 1 in slot 2. It acts only as an amplificator. A hears A+C and can substract its own component to recover the packet from C, and C similarly. Bandwidth gain is 100%.
There are a lot of implementation issues and assumptions that should be debated (it requires symmetric traffic from A to C and C to A, at least bit-wise; synchronization; error recovery mechanisms look more complicated; etc) but the main idea is quite sexy.