Showing papers by "Celimuge Wu published in 2011"

A broadcast path diversity mechanism for delay sensitive VANET safety applications

Abstract: Reliable multi-hop broadcast protocols for vehicular ad hoc networks have been widely discussed recently. However, most of them use acknowledgement based retransmissions to provide reliability. The retransmission method incurs delays when a packet loss cannot be detected on time. Acknowledgement messages also increase the MAC layer contention time at each node. In this paper, we propose a mechanism to use path diversity to provide the reliability. In the proposed mechanism, a message is disseminated by two different paths. By cooperation of these two paths, broadcast messages can be disseminated with a short delay and a high reliability compared with acknowledgement based retransmission approach. The proposed mechanism does not use any explicit acknowledgement message. We evaluate the proposed mechanism using both theoretical analysis and computer simulations.

A dynamic route change mechanism for mobile ad hoc networks

Abstract: A mobile ad hoc network (MANET) is a self-configuring network of mobile devices connected by wireless links. Frequent topology changes and limited bandwidth make communication in MANETs particularly challenging. We present a MANET routing protocol that can efficiently handle network mobility by a way of preemptively switching to a better route before the current route fails. The protocol uses a distributed Q-learning algorithm to infer network status information and takes in to consideration link stability and bandwidth efficiency while selecting a route. We study the performance of this protocol through simulation and demonstrate its advantages over existing protocols.

OFA: Opportunistic forwarding and acknowledgement for vehicular ad hoc networks

Abstract: In vehicular ad hoc networks (VANETs), providing a multi-hop communication is challenging due to the vehicle movement and lossy feature of wireless channel. Opportunistic routing provides an alternative solution with its utilization of the broadcast nature of wireless communication and the diversity of packet reception. However, most of opportunistic routing protocols specify the forwarding nodes at the sender side and therefore the opportunism cannot be fully utilized. Moreover, existing opportunistic routing protocols cannot provide a high reliability because of the lack of efficient packet reception check mechanism. In this paper, we propose OFA, an opportunistic forwarding and acknowledgement protocol for vehicular ad hoc networks. OFA performs both data forwarding and acknowledgement by taking advantage of multiuser diversity and route opportunism. In OFA, the forwarder node selection occurs at receiver nodes. An intermediate node is selected opportunistically to acknowledge the sender on the behalf the forwarder node when the forwarder node cannot communicate with the sender node directly. The proposed protocol can fully utilize the path diversity and also can provide hop-by-hop reliability.

Learning route from beaconing and interest dissemination in vehicular sensor networks

Abstract: Vehicular sensor networks can be used to collect information for the purpose of driving assistance, environment monitoring and entertainment. However, due to the vehicle movement and lossy feature of wireless channel, providing a reliable multi-hop communication between a sensor node and a sink node is particularly challenging. In this paper, we propose a protocol which learns the optimal route in the exchange of hello messages and interest messages. The proposed protocol uses a fuzzy logic to evaluate a direct wireless link and uses a Q-learning algorithm to learn the best route from a multi-hop perspective. We use computer simulations to show the effectiveness of the proposed protocol.

Fuzzy one-phase pull diffusion for WSNs in fading channel

Abstract: Using wireless sensor networks (WSNs) for a clinical purpose has many potential advantages. However, due to fading feature of wireless channel, providing an efficient and reliable communication is very challenging. In this paper, we propose FUZZ-OPP (FUZZy One-Phase Pull), a fuzzy logic based one-phase pull protocol. The protocol considers signal strength, inter-node distance and residual energy in the route selection. The protocol employs a fuzzy logic to consider these metrics jointly. Since the parameters and the rules used in the fuzzy logic are all reconfigurable, the proposed protocol can be used in any scenario by simple parameter tuning. We use computer simulations to evaluate the performance of the proposed protocol.