Sipra Das Bit

Enhancement of wireless sensor network lifetime by deploying heterogeneous nodes

Abstract Energy is one of the scarcest resources in wireless sensor network (WSN). One fundamental way of conserving energy is judicious deployment of sensor nodes within the network area so that energy flow remains balanced throughout the network. This avoids the problem of occurrence of ‘energy holes’ and ensures prolonged network lifetime. We have first investigated the problem for enhancing network lifetime using homogeneous sensor nodes. From our observation it is revealed that energy imbalance in WSN occurs due to relaying of data from different parts of the network towards sink. So for improved energy balance instead of using only sensor nodes it is desirable to deploy relay nodes in addition to sensor nodes to manage such imbalance. We have also developed a location-wise pre-determined heterogeneous node deployment strategy based on the principle of energy balancing derived from this analysis, leading to an enhancement of network lifetime. Exhaustive simulation is performed primarily to measure the extent of achieving our design goal of enhancing network lifetime while attaining energy balancing and maintaining coverage. The simulation results also show that our scheme does not compromise with other network performance metrics such as end-to-end delay, packet loss, throughput while achieving the design goal. Finally all the results are compared with two competing schemes and the results confirm our schemes supremacy in terms of both design performance metrics as well as network performance metrics.

An Enhanced Energy-Efficient Protocol with Static Clustering for WSN

Wireless Sensor Networks (WSN), consisting of a large number of sensor nodes connected through wireless medium has emerged as a ground-breaking technology that offers the unprecedented ability to monitor the physical world accurately. Because of resource-constrained nature of sensor nodes, a number of issues have emerged out of which energy-efficiency is an important matter of concern. In this work, we propose an energy-efficient routing scheme called Enhanced Energy-Efficient Protocol with Static Clustering (E3PSC) which is basically a modification of an existing routing scheme, Energy-Efficient Protocol with Static Clustering (EEPSC). Similar to EEPSC, the present work partitions the network into distance-based static clusters. However, unlike EEPSC, cluster-head selection is performed by taking into account both the spatial distribution of sensors nodes in network and their residual energy with an objective to reduce the intra-cluster communication overhead among the nodes making the scheme more energy-efficient. Both qualitative and quantitative analysis is performed to establish our claim of energy efficiency of the proposed scheme. A set of experiments is carried out to evaluate the performance of the scheme and to compare the results with EEPSC. Based on our experimental results, it has been found that E3PSC outperforms EEPSC in terms of network lifetime and energy consumption.

An energy saving audio compression scheme for wireless multimedia sensor networks using spatio-temporal partial discrete wavelet transform

Display Omitted Energy saving data compression for WMSNs with randomly deployed nodes.Energy is primarily saved by exploiting spatial and temporal correlation together.It is further saved by proposing a tree based routing which ensures unidirectional data flow toward the sink.A lossless encoding scheme is proposed to save energy further. Due to strict inherent limitations in terms of processing power, storage and bandwidth, data processing is a challenge in the wireless multimedia sensor networks. In this paper, we provide an energy-saving audio data compression technique for such a network using lifting based partial discrete wavelet transform (PDWT). Unlike existing implementation of such a lifting based PDWT, we exploit both spatial and temporal correlation of data together, with an objective to save energy while achieving acceptable signal-to-noise ratio (SNR). We subsequently design a tree based routing scheme and an encoding scheme to be used with the proposed compression scheme with a target to reduce energy further. Finally, the design feasibility along with simulation results, including statistical analysis is presented to evaluate efficacy of the scheme in terms of two conflicting parameters viz. energy consumption and SNR. The comparative results confirm our schemes supremacy over a few competing schemes.

Energy efficient audio compression scheme based on red black wavelet lifting for wireless multimedia sensor network

The availability of low-cost hardware coupled with the advancement of VLSI technology has promoted the development of wireless multimedia sensor network (WMSN). However, the strict constraints in terms of processing power, storage, bandwidth etc. pose a great challenge to data processing in WMSN. In this paper we propose an energy-saving audio data compression technique for WMSN combining wavelet lifting with a newly proposed difference detection technique for an application domain where data are correlated and placed in a 2D grid. In addition to capturing spatial correlation by wavelet, this scheme captures temporal correlation by introducing the difference detection round. A routing scheme is also proposed with a target to reduce energy consumption further. Performance of the proposed scheme is evaluated through analysis on design and simulation results. While analysis on design establishes design feasibility, simulation results evaluate efficacy of the scheme in terms of two conflicting parameters viz. energy consumption and SNR. Finally the comparative results confirm our schemes supremacy over the competing scheme in both respects.

Partial DCT-based energy efficient compression algorithm for wireless multimedia sensor network

Recent advancement in hardware technology provides sensor nodes capable to process multimedia signal. However, the strict limitations in terms of processing power, storage, bandwidth etc. pose a great challenge to data processing in wireless multimedia sensor network (WMSN). In this paper we propose an energy saving audio data compression technique for WMSN using partial DCT (PDCT), where only the last DCT coefficient is propagated thereby saves energy by transmitting reduced number of bits. We have considered an application domain where data are co-related and we have also considered a 2D architecture where nodes are randomly placed. Along with the proposed PDCT based scheme a tree based routing scheme is also proposed with an aim to reduce energy consumption further. The design feasibility along with simulation results evaluate efficacy of the scheme in terms of two conflicting parameters viz. energy consumption and SNR. The comparative results confirm our schemes supremacy over the competing scheme.

Low-overhead image compression in WMSN for post disaster situation analysis

Due to inherent limitations in terms of processing power, storage, and bandwidth, data processing is a challenge in wireless multimedia sensor network (WMSN). Transmitting raw data is very costly while limited processing power of the sensor nodes prevents sophisticated multimedia processing. Exploring low-overhead data compression technique is a solution towards this problem. In this work we propose an energy saving image compression technique for WMSN by partial discrete cosine transform (PDCT) considering the application of post-disaster situation analysis through image capturing of the affected area. Here the DCT coefficients of only the last two rows of macroblock of the sensory image are propagated thereby saves energy by transmitting reduced number of bits. Also an existing tree based routing scheme is modified to employ in-network aggregation at merging nodes along the tree saving energy further. Finally the design feasibility along with simulation results including statistical analysis is presented to evaluate efficacy of the scheme in terms of two conflicting parameters viz. energy consumption and peak signal to noise ratio (PSNR). The comparative results confirm our schemes supremacy in WMSN application domain over existing methods.

Best-effort delivery of emergency messages in post-disaster scenario with content-based filtering and Priority-enhanced PRoPHET over DTN

Despite concerted efforts for relaying crucial situational information, disaster relief volunteers experience significant communication challenges owing to failures of critical infrastructure and longstanding power outages in disaster affected areas. Researchers have proposed the use of smartphones, working in delay tolerant (DTN) mode, for setting up a peer-to-peer network enabling post disaster communication. However, due to opportunistic contacts, intermittent connectivity and constrained resources (mainly battery) of mobile devices, not all messages get forwarded in such a network. As a result, several crucial messages, waiting in the buffer may get dropped and unimportant, extraneous (sentimental comments of victims, etc.) messages may get transmitted at the cost of expensive network resources. Therefore, filtering out such irrelevant messages (containing unrelated information and emotional expressions) and prioritizing relevant messages according to its importance becomes crucial so that messages which are critical for decision making receive the highest priority and get disseminated in the network at the minimum possible time. In this paper, our objective is to ensure best-effort delivery of emergency messages using a two-step approach, (i) segregation of high priority messages through natural language processing based filtering and (ii) dissemination of filtered messages over DTN using a Priority-enhanced PRoPHET routing protocol which is developed by adapting the popular PRoPHET routing protocol. The protocol successfully achieves on-the-fly message prioritization and ensures best effort delivery of such prioritized messages to their appropriate destinations. The proposed protocol is evaluated using the ONE simulator. Simulation results suggest that our protocol outperforms other well known DTN routing protocols like PRoPHET, Spray-And-Wait, MaxProp and Epidemic in terms of delivery ratio of prioritized messages and overhead ratio.

A jamming-attack-defending data forwarding scheme based on channel surfing in wireless sensor networks

Wireless sensor networks (WSNs) are susceptible to various attacks, and these attacks pose a major threat to the normal functioning of WSNs. Jamming is one such attack, which affects network operations by blocking frequencies. Hence, the need of defending such attack is of utmost importance. This paper proposes three variants of a data forwarding scheme using multi-level multi-tier architecture, which employs judicious surfing of a pair of channels to defend jamming attack in WSNs. Variant I defends the attack at the cost of an affordable delay. Improvement of the scheme in minimizing data transmission time is made in variant II. Further improvement in transmission time is made in variant III and is made more realistic by introducing sensing capability at all tiers, thereby increasing network coverage. Simulation is performed to establish each of the successors variants improvement over its predecessor. The performance of the scheme in terms of area coverage, packet delivery ratio, and control message overhead is compared with an existing jamming-defending scheme for infrastructure-based wireless network. Finally, comparison results establish that although the proposed scheme is equivalent to its infrastructure-based counterpart in terms of coverage, it provides a more lightweight solution and maintains improved performance in terms of packet delivery ratio. Copyright

Performance of a Partial Discrete Wavelet Transform Based Path Merging Compression Technique for Wireless Multimedia Sensor Networks

Wireless multimedia sensor network is well-known for its constraints in the field of multimedia processing in terms of processing power, bandwidth etc. Data processing is always a challenge in such network. Exploiting low overhead compression accompanied by proper routing and aggregation is a challenge for such energy starved multihop network. In this paper, we propose an efficient path merging protocol for wireless multimedia sensor network with randomly deployed nodes. Any partial discrete wavelet transform based compression technique can be plugged into this path merging protocol to reduce redundant data transmission in a significant manner by appropriate aggregation of data packets from merging paths. The design feasibility and the simulation results prove supremacy of our protocol over state-of-the-art competing schemes in terms of maintaining a trade-off between energy consumption and reconstruction quality.

Hm2Sc: Human Movement Model for Post Disaster Scenario in Smart City

In this work, we propose a human movement model that characterizes the movement pattern of different stakeholders in a post-disaster scenario in smart city. Knowledge about such mobility pattern assists in designing fast deployable smartphone based delay-tolerant network for disseminating post-disaster crucial situational information in a smart city. To the best our knowledge, this model is a major step ahead in the arena of mobility models for a post-disaster scenario in a smart city environment specifically considering the rescue operations. We provide extensive analytical foundations to strengthen the proposed mobility model. Simulation results justify that routing protocols when applied with proposed movement model, optimize network performances in terms of delivery ratio, overhead ratio and average residual energy at the cost of tolerable latency.