Low Power, Low Delay: Opportunistic Routing meets Duty Cycling

Traditionally, routing in wireless sensor networks consists of two steps: First, the routing protocol selects a next hop, and, second, the MAC protocol waits for the intended destination to wake up and receive the data. This design makes it difficult to adapt to link dynamics and introduces delays while waiting for the next hop to wake up. In this paper we introduce ORW, a practical opportunistic routing scheme for wireless sensor networks. In a dutycycled setting, packets are addressed to sets of potential receivers and forwarded by the neighbor that wakes up first and successfully receives the packet. This reduces delay and energy consumption by utilizing all neighbors as potential forwarders. Furthermore, this increases resilience to wireless link dynamics by exploiting spatial diversity. Our results show that ORW reduces radio duty-cycles on average by 50% (up to 90% on individual nodes) and delays by 30% to 90% when compared to the state of the art

A New Routing Protocol for WMNs

Opportunistic routing is an emerging research area in Wireless Mesh Networks (WMNs), which exploits the broadcast nature of wireless networks to find the optimal routing solution that maximizes throughput and minimizes packet loss. Opportunistic routing protocols mainly suffer from computational overheads, as most of the protocols try to find the best next forwarding node. In this paper we address the key issue of computational overhead by designing new routing technique without using pre-selected list of potential forwarders. We propose a novel opportunistic routing technique for WMNs. We compare it with well-known protocols, such as AODV, OLSR, and ROMER based on throughput, delivery ratio, and average end to end delay. Simulation results show that proposed protocol, gives average throughput increase up to 32%, and increase in delivery ratio (from 10% to 20%). We also analyze the performance of proposed protocol and ROMER based on various parameters, such as duplicate transmissions and network collisions, by analysis depicts that proposed protocol reduces duplicate transmissions up to 70% and network collisions up to 30% DOI: 10.17762/ijritcc2321-8169.15026

Opportunistic Source Coding for Data Gathering in Wireless Sensor Networks

We propose a jointly opportunistic source coding and opportunistic routing (OSCOR) protocol for correlated data gathering in wireless sensor networks. OSCOR improves data gathering efficiency by exploiting opportunistic data compression and cooperative diversity associated with wireless broadcast advantage. The design of OSCOR involves several challenging issues across different network protocol layers. At the MAC layer, sensor nodes need to coordinate wireless transmission and packet forwarding to exploit multiuser diversity in packet reception. At the network layer, in order to achieve high diversity and compression gains, routing must be based on a metric that is dependent on not only link-quality but also compression opportunities. At the application layer, sensor nodes need a distributed source coding algorithm that has low coordination overhead and does not require the source distributions to be known. OSCOR provides practical solutions to these challenges incorporating a slightly modified 802.11 MAC, a distributed source coding scheme based on network coding and Lempel-Ziv coding, and a node compression ratio dependent metric combined with a modified Dijkstra's algorithm for path selection. We evaluate the performance of OSCOR through simulations, and show that OSCOR can potentially reduce power consumption by over 30% compared with an existing greedy scheme, routing driven compression, in a 4 x 4 grid network

Opportunistic routing in multi-hop wireless networks

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Includes bibliographical references (leaves 45-47).This thesis describes ExOR, an integrated routing and MAC protocol for bulk transfers in multi-hop wireless networks. ExOR exploits the broadcast nature of radios by making forwarding decisions based on which nodes receive each transmission. The spatial diversity among receivers provides each transmission multiple opportunities to make progress in the face of packet losses. As a result ExOR can use long links with high loss rates, which would be avoided by unicast routing. ExOR operates on batches of packets. The source node includes a list of candidate forwarders in each packet, prioritized by closeness to the destination. Receiving nodes buffer successfully received packets and await the end of the batch. The highest priority forwarder then broadcasts the packets in its buffer, including its copy of the "batch map" in each packet. The batch map contains the sender's best guess of the highest priority node to have received each packet. The remaining forwarders then transmit in order, sending only packets which were not acknowledged in the batch maps of higher priority nodes. The forwarders continue to cycle through the priority list until the destination has enough packets to recover the original data using forward error correction.(cont.) An evaluation of an implementation on a 38-node 802.11b test-bed shows that ExOR improves bulk data transfer throughput for most node pairs when compared with unicast routing. For pairs between which unicast uses one or two hops, ExOR's robust batch maps prevent unnecessary retransmissions, increasing throughput by nearly 50%. For longer unicast routes, ExOR takes advantage of spatial diversity, providing gains of a factor of two to four when using a batch size of 10 packets.by Sanjit Zubin Biswas.S.M

Study on Packet Forwarding Mechanism by Narrowing Relay Range in Ad Hoc Networks

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