Performance Evaluation of a Power Management Scheme for Disruption Tolerant Network

Abstract

Disruption Tolerant Network (DTN) is characterized by frequent partitions and intermittent connectivity. Power management issue in such networks is challenging. Existing power management schemes for wireless networks cannot be directly applied to DTNs because they assume the networks are well-connected. Since the network connectivity opportunities are rare, any power management scheme deployed in DTNs should not worsen the existing network connectivity. In this paper, we design a power management scheme called context-aware power management scheme (CAPM) for DTNs. Our CAPM scheme has an adaptive on period feature that allows it to achieve high delivery ratio and low delivery latency when used with Prophet, a recently proposed DTN routing scheme. Via simulations, we evaluate the performance of the CAPM scheme when used with the Prophet routing scheme in different scenarios e.g. different traffic load, node speeds and sleep patterns. Our evaluation results indicate that the CAPM scheme is very promising in providing energy saving (as high as 80%) without degrading much the data delivery performance.

Adaptive Asynchronous Sleep Scheduling Protocols for Delay Tolerant Networks

“…However, as in QPS, each n must be a perfect square, and active slot ratio of sets are twice the optimal active slot ratio provided by CDS [22]. In DTN, CAPM [30] determines the sleep schedule based on known node densities and traffic load requirements. Although the determined sleep schedules are fixed and not adaptive, we classify CAPM as an adaptive protocol since the sleep schedule of CAPM that achieves the lowest active slot ratio is the same as the sleep schedule of AQEC, as will be explained in Section 7.1.…”

“…A complete cycle of the sleep schedule is called a frame, and its length is denoted by L f . A frame may consist of unequal sized intervals as in [30] or equal sized intervals, called slots, forming a set as in [21], [23], [24], [26], [33]. For the protocols with unequal sized slots, let L on and L off , respectively, represent the duration of active intervals and inactive intervals.…”

“…However, in DTN with sparsely connected nodes, the cycle lengths are relatively large, up to several seconds in many DTN scenarios, since small cycle lengths waste energy without discovering many more contacts [30], [31]. Also, the main source of energy waste that needs to be reduced is caused by the idle listening problem.…”

“…In specific, AQEC [21] and HQS [26] are considered for the direct comparison. Other existing adaptive asynchronous sleep scheduling protocols, CAPM [30], AAPM [23], and ACQ [24], are not considered in the comparison for the following reasons: CAPM shares the similar frame structure with AQEC, and the sleep schedule of CAPM that achieves the lowest active ratio is the same as the sleep schedule of AQEC; AAPM is limited to small set sizes, since the collection of sets that satisfy the rotational closure property is rare for n > 50, as shown in Fig. 7; ACQ is limited to two power saving levels and a-quorums fail to discover each other, as previously explained in Section 2.…”

“…Under opportunistic contacts, with synchronized clocks, beacon intervals are adaptively adjusted in AEB [29]. An asynchronous clockbased sleep scheduling protocol is proposed in CAPM [30], where sleep schedules are determined based on node densities and traffic load requirements. These adaptive protocols balance the trade-off between energy consumption and connectivity to improve performance considering dynamic node mobility characteristics.…”