@TechReport{	  it:2002-022,
  author	= {Henrik Lundgren and Erik Nordstr{\"o}m and Christian
		  Tschudin},
  title		= {Coping with Communication Gray Zones in {IEEE} 802.11b
		  based Ad hoc Networks},
  institution	= {Department of Information Technology, Uppsala University},
  department	= {Division of Computer Systems},
  year		= {2002},
  number	= {2002-022},
  month		= jun,
  abstract	= {Our experiments with IEEE 802.11b based wireless ad hoc
		  networks show that neighbor sensing with broadcast messages
		  introduces ``communication gray zones'': in such zones data
		  messages cannot be exchanged although the HELLO messages
		  indicate neighbor reachability. This leads to a systematic
		  mismatch between the route state and the real world
		  connectivity, resulting in disruptive behavior for some ad
		  hoc routing protocols. Concentrating on AODV we explore
		  this issue and evaluate three different techniques to
		  overcome the gray zone problem. We present quantitative
		  measurements of these improvements and discuss the
		  consequences for ad hoc routing protocols and their
		  implementations. }
}