Queueing Syst (2012) 72:31–68 DOI 10.1007/s11134-012-9289-7 On optimizing CSMA for wide area ad hoc networks Francois Baccelli · Junyi Li · Thomas Richardson · Sanjay Shakkottai · Sundar Subramanian · Xinzhou Wu Received: 16 May 2011 / Published online: 19 April 2012 © Springer Science+Business Media, LLC 2012 Abstract The recent deployment of data-rich smart phones has led to a fresh impetus for understanding the performance of wide area ad hoc networks. The most popular medium access mechanism for such ad hoc networks is CSMA/CA with RTS/CTS. In CSMA-like mechanisms, spatial reuse is achieved by implementing energy-based guard zones. We consider the problem of simultaneously scheduling the maximum number of links that can achieve a given signal to interference ratio (SIR). In this paper, using tools from stochastic geometry, we study and maximize the medium access probability of a typical link. Our contributions are two-fold: (i) We show that a simple modification to the RTS/CTS mechanism, viz., changing the receiver yield decision from an energy-level guard zone to an SIR guard zone, leads to performance gains; and (ii) We show that this combined with a simple modification to the transmit power level—setting it inversely proportional to the square root of the link gain— F. Baccelli ( ) Département d’Informatique, INRIA—École Normale Supérieure, 45 rue d’Ulm, Paris, France e-mail: Francois.Baccelli@ens.fr J. Li · T. Richardson · S. Subramanian · X. Wu Qualcomm Flarion Tech., 500 Somerset Corporate Blvd., Bridgewater, NJ, USA J. Li e-mail: junyil@qualcomm.com T. Richardson e-mail: tomr@qualcomm.com S. Subramanian e-mail: sundars@qualcomm.com X. Wu e-mail: xinzhouw@qualcomm.com S. Shakkottai Department of Electrical and Computer Engineering, University of Texas at Austin, Austin, TX, USA e-mail: shakkottai@mail.utexas.edu