Zhifeng Tao Thanasis Korakis Feilu Liu Shivendra S. Panwar Jinyun Zhang Leandros Tassiulas Cooperation and Directionality: Friends or Foes? 4424-4430 2008 ICC http://dx.doi.org/10.1109/ICC.2008.830 conf/icc/2008 db/conf/icc/icc2008.html#TaoKLPZT08