The 4th International Conference on Ad-Hoc Networks and Wireless (ADHOC- NOW 2005)was held October 6 8,2005in Cancun, Mexico. Adhoc Now started as a workshop in 2002 and was held at the Fields Institute in Toronto. In 2003, it was held in Montreal, and in 2004 it was held in Vancouver. 2005 was the ?rst yearfortheconferencetomoveoutsideofCanada.Thepurposeoftheconference is to create a collaborative forum between mathematicians, computer scientists, and engineers for research in the ?eld of mobile ad hoc and sensor networks. In 2005, we received over 100 submissions from 22 di?erent countries: Australia,Canada,China,France,Germany,Greece,India,Ireland,Italy,Japan, Korea, Malaysia, Mexico, Nepal, Nigeria, Pakistan, Poland, Spain, Sweden, Tunisia, the UK, and the USA a true international conference. Of the papers submitted, we selected 27 for presentation at the conference and publication in the proceedings. We are grateful to our Technical Program, Organizing, and Steering C- mittees; without their help, expertise, and experiencewe could not haveselected such a ?ne program. We thank Jorge Urrutia of the Instituto de Matem aticas, Universidad NacionalAut onoma de M exico,and J.J. Garcia-Luna-Acevesof the Computer Engineering Department, University of California, Santa Cruz for - cepting our invitation to speak at the conference. Special thanks are due to the crewfromtheFacultaddeCienciasF ?sico-Matem aticasUniversidadMichoacana for handling the local arrangements, and to the Mobile Adhoc Research Lab at Arizona State University for handling odd jobs on a moment s notice.

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Invited Presentations.- Another Look at Dynamic Ad-Hoc Wireless Networks.- Routing in Wireless Networks and Local Solutions for Global Problems.- Contributed Papers.- Equilibria for Broadcast Range Assignment Games in Ad-Hoc Networks.- Efficient Mechanisms for Secure Inter-node and Aggregation Processing in Sensor Networks.- Cluster-Based Framework in Vehicular Ad-Hoc Networks.- Randomized AB-Face-AB Routing Algorithms in Mobile Ad Hoc Networks.- A Multiple Path Characterization of Ad-Hoc Network Capacity.- Increasing the Resource-Efficiency of the CSMA/CA Protocol in Directional Ad Hoc Networks.- Location Tracking in Mobile Ad Hoc Networks Using Particle Filters.- Biology-Inspired Distributed Consensus in Massively-Deployed Sensor Networks.- A Key Management Scheme for Commodity Sensor Networks.- Playing CSMA/CA Game to Deter Backoff Attacks in Ad Hoc Wireless LANs.- Design of a Hard Real-Time Guarantee Scheme for Dual Ad Hoc Mode IEEE 802.11 WLANs.- Selective Route-Request Scheme for On-demand Routing Protocols in Ad Hoc Networks.- Enhancing the Security of On-demand Routing in Ad Hoc Networks.- DPUMA: A Highly Efficient Multicast Routing Protocol for Mobile Ad Hoc Networks.- Efficient Broadcasting in Self-organizing Multi-hop Wireless Networks.- MIMOMAN: A MIMO MAC Protocol for Ad Hoc Networks.- Reed-Solomon and Hermitian Code-Based Scheduling Protocols for Wireless Ad Hoc Networks.- An Intelligent Sensor Network for Oceanographic Data Acquisition.- Performance Analysis of the Hierarchical Layer Graph for Wireless Networks.- Heuristic Algorithms for Minimum Bandwith Consumption Multicast Routing in Wireless Mesh Networks.- Probability Distributions for Channel Utilisation.- Enhanced Power-Aware Routing for Mobile Ad Hoc Networks.- Message Stability and Reliable Broadcasts in Mobile Ad-Hoc Networks.- A Detection Scheme of Aggregation Point for Directed Diffusion in Wireless Sensor Networks.- Stressing is Better Than Relaxing for Negative Cost Cycle Detection in Networks.- Cache Placement in Sensor Networks Under Update Cost Constraint.- A Service Discovery Protocol with Maximal Area Disjoint Paths for Mobile Ad Hoc Networks.- Erratum.- Erratum.