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Abstract

SummaryReactive routing protocols for mobile ad hoc networks reduce the routing cost in high mobility environments where link failures are frequent. However, route discovery in these protocols is typically performed via networkwide flooding, which consumes a substantial amount of bandwidth and causes a significant latency to data packets. To improve the dynamic source routing (DSR) protocol and overcome these limitations, we propose two optimization techniques, viz. generalized salvaging mechanism and cache maintenance using a distributed topology discovery mechanism through mobile ant-agents. We show, by simulations, that our contributions improve the DSR performance, and particularly in large scale networks with high mobility and heavy load that cause frequent link failures.

Cooperative Incumbent System Protection MAC Protocol for Multi-channel Ad-hoc Cognitive Radio Networks

“…After the ATIM window, the nodes will switch to their agreed channels and exchange messages during the remainder of the beacon interval. DCR-MAC [7] discovers a new hidden incumbent node problem and proposes an efficient neighbor reporting solution. In [7], the incumbent signal sensing scheme is not only performed by the communicatin pair, but also with the cooperation of their neighbors and the revolutionary pulse based sensing reporting scheme, it is able to provide reliable protection to the incumbent system working around.…”

“…DCR-MAC [7] discovers a new hidden incumbent node problem and proposes an efficient neighbor reporting solution. In [7], the incumbent signal sensing scheme is not only performed by the communicatin pair, but also with the cooperation of their neighbors and the revolutionary pulse based sensing reporting scheme, it is able to provide reliable protection to the incumbent system working around. Since DCR-MAC relies on the separated common control channel and only cares about the single hop issues, [8] proposed a synchronization MAC where separared common control channels can be avoided, and [9] extends [7] and proposes a distributed multichannel MAC protocol for multi-hop cognitive radio networks with energy efficient concept in consideration, respectively.…”

“…In [7], the incumbent signal sensing scheme is not only performed by the communicatin pair, but also with the cooperation of their neighbors and the revolutionary pulse based sensing reporting scheme, it is able to provide reliable protection to the incumbent system working around. Since DCR-MAC relies on the separated common control channel and only cares about the single hop issues, [8] proposed a synchronization MAC where separared common control channels can be avoided, and [9] extends [7] and proposes a distributed multichannel MAC protocol for multi-hop cognitive radio networks with energy efficient concept in consideration, respectively. In [10], a cognitive MAC protocol is proposed for multichannel wireless networks (C-MAC), which operates over multiple channels and thus able to effectively deal with the dynamics of resource availability due to PUs and mitigate the effects of distributed quiet periods utilized for PU signal detection.…”

“…Since each sensing node can detect the primary signal within the sensing interval, the sensing interval should not be larger than the allowed interference time (e.g., channel move time <=2sec in TV band defined in the IEEE 802.22 standard). As a result, the timing condition related to the sensing interval and time slot size is as in (7).…”