@article{qun_jsac07,
	author = {Lei Guo and Xiaoning Ding and Haining Wang and Qun
	Li and Songqing Chen and Xiaodong Zhang},
	title = {Cooperative Relay Service in a Wireless {LAN}},
	journal = {{IEEE} Journals on Selected Areas in Communications},
	year = {2007},
	month = {Feb.},
	volume = {25},
	number = {2},
	pages = {355--368},
	publisher = {},
	earlier = {},
	later = {},
	url = {}
	}

Abstract


As a family of wireless local area network (WLAN)
protocols between physical layer and higher layer protocols,
IEEE 802.11 has to accommodate the features and requirements
of both ends. However, current practice has addressed the problems
of these two layers separately and is far from satisfactory.
On one end, due to varying channel conditions, WLANs have
to provide multiple physical channel rates to support various
signal qualities. A low channel rate station not only suffers low
throughput, but also significantly degrades the throughput of
other stations. On the other end, the power saving mechanism of
802.11 is ineffective in TCP-based communications, in which the
wireless network interface (WNI) has to stay awake to quickly
acknowledge senders, and hence, the energy is wasted on channel
listening during idle awake time.

In this paper, considering the needs of both ends, we utilize the
idle communication power of the WNI to provide a Cooperative
Relay Service (CRS) for WLANs with multiple channel rates.
We characterize energy efficiency as energy per bit, instead
of energy per second. In CRS, a high channel rate station
relays data frames as a proxy between its neighboring stations
with low channel rates and the Access Point, improving their
throughput and energy efficiency. Different from traditional
relaying approaches, CRS compensates a proxy for the energy
consumed in data forwarding. The proxy obtains additional
channel access time from its clients, leading to the increase of
its own throughput without compromising its energy efficiency.
Extensive experiments are conducted through a prototype implementation
and ns-2 simulations to evaluate our proposed CRS.