This paper addresses the problem of efficient packet forwarding in a multihop, wireless "mesh" network. We present an efficient interface contained forwarding (ICF) architecture for a "wireless router," i.e., a forwarding node with a single wireless network interface card (NIC) in a multihop wireless network that allows a packet to be forwarded entirely within the NIC of the forwarding node without requiring per-packet intervention by the node's CPU. To effectively forward packets in a pipelined fashion without incurring the 802.11-related overheads of multiple independent channel accesses, we specify a slightly modified version of the 802.11 MAC, called data driven cut-through multiple access (DCMA) that uses multiprotocol label switching (MPLS)-like labels in the control packets, in conjunction with a combined ACK/RTS packet, to reduce 802.11 channel access latencies. Our proposed technique can be used in combination with "frame bursting" as specified by the IEEE 802.11e standard to provide an end-to-end cut-through channel access. Using extensive simulations, we compare the performance of DCMA with 802.11 DCF MAC with respect to throughput and latency and suggest a suitable operating region to get maximum benefits using our mechanism as compared to 802.11

This paper presents an overview of the ORBIT (open access research testbed for next-generation wireless networks) radio grid testbed, that is currently being developed for scalable and reproducible evaluation of next-generation wireless network protocols. The ORBIT testbed consists of an indoor radio grid emulator for controlled experimentation and an outdoor field trial network for end-user evaluations in real-world settings. The radio grid system architecture is described in further detail, including an identification of key hardware and software components. Software design considerations are discussed for the open-access radio node, and for the system-level controller that handles management and control. The process of specifying and running experiments on the ORBIT testbed is explained using simple examples. Experimental scripts and sample results are also provided.

This paper describes a beacon assisted discovery mechanism for self-organizing hierarchical ad-hoc networks. The discovery protocol, which operates between the medium access control (MAC) and network layers, is responsible for topology formation in the ad-hoc network taking into account performance objectives such as throughput, delay, energy consumption and robustness. The proposed discovery protocol operates by listening to augmented MAC-layer beacons from neighboring radio nodes and then selects a subset of these for routing associations based on specified criteria. A distributed heuristic algorithm for topology formation is considered and compared with upper-bound centralized algorithms with optimization objectives such as maximum throughput, minimum delay or minimum energy. Simulation results (based on ns-2 models) are given for the performance of the proposed discovery methods, demonstrating significant improvements in routing overhead when compared to an ad hoc network without discovery. A proof-of-concept prototype implementation for an IEEE 802.11b-based three-tier hierarchical ad hoc network is briefly described in conclusion.

Current "best practice" recommendations for enterprise wireless deployments suggest the use of VPNs from a wireless client for both authentication and privacy. In this paper, we demonstrate a security issue with such deployments, which we refer to as the hidden wireless router vulnerability. This vulnerability is inherent in the VPN-based wireless LAN architecture, and leads to unsuspecting clients becoming conduits for an attack, exploiting features readily available in popular operating systems like Windows and Linux. We describe the attack scenario, and possible solutions for both detecting and locating such hidden wireless routers. Our solutions include a range of possibilities stretching from purely passive to active probing methods, and access point-based solutions. We describe our techniques and results of our implementation and experiments.

We present LEASE, a new system and framework for location estimation assisted by stationary emitters for indoor RF wireless networks. Unlike previous studies, we emphasize the deployment aspect of location estimation engines. Motivated thus, we present an adaptable infrastructure-based system that uses a small number of stationary emitters (SEs) and sniffers employed in a novel way to locate standard wireless clients in an enterprise. We present the components of the system and its architecture, and new non-parametric techniques for location estimation that work with a small number of SEs. Our techniques for location estimation can also be used in a client-based deployment. We present experimental results of using our techniques at two sites demonstrating the ability to perform location estimation with good accuracy in our new adaptable framework.

This paper describes the design and implementation of a novel 802.11-based self-organizing hierarchical ad-hoc wireless network (SOHAN), and presents some initial experimental results obtained from a proof-of-concept prototype. The proposed network has a three-tier hierarchy consisting of low-power mobile nodes (MNs) at the lowest layer, forwarding nodes (FNs) with higher power and multi-hop routing capability at the middle layer, and wired access points (APs) without power constraints at the highest layer. Specifics of new protocols used for bootstrapping, node discovery, and multi-hop routing are presented, and the overall operation of the complete hierarchical ad-hoc network is explained. A prototype implementation of the SOHAN network is outlined in terms of major hardware and software components, and initial experimental results are given.