# Columbia University Joint CS/EE Networking Seminar Series

**Optimal Tradeoff between Exposed and Hidden Nodes in Large Wireless Networks**

**Peter van de Ven**^{}

IBM T.J. Watson Research Lab

**January 23, 2:00-3:00PM, CEPSR 414**

**Abstract:**
Wireless networks equipped with the CSMA protocol are subject to collisions due to interference. For a given interference range we investigate the tradeoff between collisions (hidden nodes) and unused capacity (exposed nodes). We show that the sensing range that maximizes throughput critically depends on the activation rate of nodes. For infinite line networks, we prove the existence of a threshold: When the activation rate is below this threshold the optimal sensing range is small (to maximize spatial reuse). When the activation rate is above the threshold the optimal sensing range is just large enough to preclude all collisions. Simulations suggest that
this threshold policy extends to more complex linear and non-linear topologies.

**Speaker Biography**:
Peter van de Ven received the M.Sc. degree in Applied Mathematics in 2007 from Eindhoven University of Technology, The Netherlands; From 2007-2011 he was a Ph.D. student there working on stochastic models for wireless networks. He is currently the Goldstine postdoctoral fellow at the IBM T.J. Watson Research Lab. His research interests are in scheduling, queueing theory and the performance analysis of wireless networks