Towards overhead mitigation in state-free geographic forwarding protocols for wireless sensor networks

Wireless Networks - Routing has been the most consumptive of all processes engaged in the Wireless Sensor Network communications, thus improving this consumptive process by minimizing the number of...     

A MAC/Routing cross-layer approach to geographic forwarding in wireless sensor networks

Geographic forwarding is an emerging paradigm for communications between nodes in sensor networks. No exchange of location information is required, and nodes only have to know their own coordinates and those of the destination. Due to the device’s limited processing and storage capabilities, a simplified protocol architecture should be designed so as to make communications in these networks efficient and simple at the same time. Moreover, sensor nodes are battery supplied and, thus, protocol design should be aimed at reducing energy consumption in order to increase network lifetime. In this perspective, one sensor feature recently regarded as of key importance, is the ability to tune the transmission power. This allows the communication range to be varied according to node density and connectivity constraints. In this paper we propose an integrated cross-layer protocol, called MACRO, which integrates MAC and routing layer functionalities in order to support geographic forwarding in wireless sensor networks. In MACRO, a competition is triggered to select the best next relay node while forwarding information to the destination. The competition is based on the evaluation of a weighted progress factor representing the progress towards the destination per unit of transmission power. An analytical paradigm facilitating the most appropriate choice of the next relay is proposed. The proposed solution is assessed through both analysis and ns-2 simulations. Performance results show the advantages of the proposed solution when compared to other geographic forwarding protocols which do not exploit cross-layer features.     

MC-LMAC: A multi-channel MAC protocol for wireless sensor networks

In traditional wireless sensor network (WSN) applications, energy efficiency may be considered to be the most important concern whereas utilizing bandwidth and maximizing throughput are of secondary importance. However, recent applications, such as structural health monitoring, require high amounts of data to be collected at a faster rate. We present a multi-channel MAC protocol, MC-LMAC, designed with the objective of maximizing the throughput of WSNs by coordinating transmissions over multiple frequency channels. MC-LMAC takes advantage of interference and contention-free parallel transmissions on different channels. It is based on scheduled access which eases the coordination of nodes, dynamically switching their interfaces between channels and makes the protocol operate effectively with no collisions during peak traffic. Time is slotted and each node is assigned the control over a time slot to transmit on a particular channel. We analyze the performance of MC-LMAC with extensive simulations in Glomosim. MC-LMAC exhibits significant bandwidth utilization and high throughput while ensuring an energy-efficient operation. Moreover, MC-LMAC outperforms the contention-based multi-channel MMSN protocol, a cluster-based channel assignment method, and the single-channel CSMA in terms of data delivery ratio and throughput for high data rate, moderate-size networks of 100 nodes at different densities.     

A new hybrid key pre-distribution scheme for wireless sensor networks

This article presents a novel hybrid key pre-distribution scheme based on combinatorial design keys and pair-wise keys. For the presented scheme, the deployment zone is cleft into equal-sized cells. We use the combinatorial design based keys to secure intra-cell communication, which helps to maintain low key storage overhead in the network. For inter-cell communication, each cell maintain multiple associations with all the other cells within communication range and these associations are secured with pair-wise keys. This helps to ensure high resiliency against compromised sensor nodes in the network. We provide in-depth analysis for the presented scheme. We measure the resiliency of the presented scheme by calculating fraction of links effected and fraction of nodes disconnected when adversary compromises some sensor nodes in the network. We find that the presented scheme has high resiliency than majority of existing schemes. Our presented scheme also has low storage overhead than existing schemes.

     

A light-weight authentication scheme for wireless sensor networks

Sensor networks are ad hoc mobile networks that include sensor nodes with limited computational and communication capabilities. They have become an economically viable monitoring solution for a wide variety of applications. Obviously, security threats need to be addressed and, taking into account its limited resources, the use of symmetric cryptography is strongly recommended. In this paper, a light-weight authentication model for wireless sensor networks composed of a key management and an authentication protocol is presented. It is based on the use of simple symmetric cryptographic primitives with very low computational requirements, which obtains better results than other proposals in the literature. Compared to SPINS and BROSK protocols, the proposal can reduce energy consumption by up to 98% and 67%, respectively. It also scales well with the size of the network, due to it only requiring one interchanged message, independently of the total number of nodes in the network.     

A group-based security scheme for wireless sensor networks

In recent years, wireless sensor networks have been a very popular research topic, offering a treasure trove of systems, networking, hardware, security, and application-related problems. Distributed nature and their deployment in remote areas, these networks are vulnerable to numerous security threats that can adversely affect their proper functioning. The problem is more critical if its purpose is for some mission-critical applications such as in a tactical battlefield. This paper presents a security scheme for group-based distributed wireless sensor networks. Our first goal is to devise a group-based secure wireless sensor network. We exploit the multi-line version of matrix key distribution technique and Gaussian distribution to achieve this goal. Secondly, security mechanisms are proposed for such a group-based network architecture in which sensed data collected at numerous, inexpensive sensor nodes are filtered by local processing on its way through more capable and compromise-tolerant reporting nodes. We address the upstream requirement that reporting nodes authenticate data produced by sensors before aggregating and the downstream requirement that sensors authenticates commands disseminated from reporting nodes. Security analysis is presented to quantify the strength of the proposed scheme against security threats. Through simulations, we validate the analytical results.     

Contention‐based geographic forwarding in asynchronous duty‐cycled wireless sensor networks

In asynchronous duty‐cycled wireless sensor networks, it is desirable that the data forwarding scheme is adaptive to the dynamics caused by the uncertainty of sensor nodes’ working schedules. Contention‐based forwarding is designed to adapt to the dynamic environments. In this work, we are interested in the contention‐based geographic forwarding (CGF) for two asynchronous duty‐cycling (ADC) models, which we refer to as uninterruptible ADC (U‐ADC) and interruptible ADC (I‐ADC). We propose a new residual time‐aware routing metric for CGF in the I‐ADC model and present a residual time‐aware forwarding scheme using this metric. We evaluate the performance of CGF in both asynchronous duty‐cycling models. Simulation results show that CGF in the U‐ADC model provides a shorter delivery delay while suffering from a high sender effective duty cycle problem. CGF in the I‐ADC model incurs a very long data delivery delay, but it can achieve a good load balancing among nodes. It is also demonstrated that the proposed residual time‐aware forwarding scheme lowers the effects of the performance degradation caused by the pure asynchronous duty‐cycling operation. Copyright © 2011 John Wiley & Sons, Ltd.     

CNS: a new energy efficient transmission scheme for wireless sensor networks

We present in this paper a new energy-efficient communication scheme called CNS (Compression with Null Symbol) that combines the power of data compression and communication through silent symbol. The concept of communication through silent symbol is borrowed from the energy efficient schemes proposed in Sinha (Proceedings of 6th IEEE consumer communications and networking conference (CCNC), Las Vegas, pp. 1–5, 2009), Ghosh et al. (Proceedings of 27th IEEE international performance computing and communications conference (IPCCC), USA, pp. 85–92, 2008), and Sinha and Sinha (Proceedings of international conference on distributed computing and internet technologies (ICDCIT), LNCS, pp. 139–144, 2008). We show that the average theoretical energy saving at the transmitter by CNS is 62.5%, assuming an ideal channel and for equal likelihood of all possible binary strings of a given length. Next, we propose a transceiver design that uses a hybrid modulation scheme utilizing FSK and ASK so as to keep the cost/complexity of the radio devices low. Considering an additive white gaussian noise (AWGN) channel and a non-coherent detection based receiver, CNS shows a saving in transmitter energy by 30% when compared to binary FSK, for equal likelihood of all possible binary strings of a given length. Simultaneously, there is a saving of 50% at the receiver for all types of data modulation due to halving of the transmitted data duration, compared to binary encoding. In contrast, RBNSiZeComm proposed in Sinha (Proceedings of 6th IEEE consumer communications and networking conference (CCNC), Las Vegas, pp. 1–5, 2009), TSS proposed in Ghosh et al. (Proceedings of 27th IEEE international performance computing and communications conference (IPCCC), USA, pp. 85–92, 2008) and RZE proposed in Sinha and Sinha (Proceedings of international conference on distributed computing and internet technologies (ICDCIT), LNCS, pp. 139–144, 2008) generate average transmitter energy savings of about 41, 20, and 35.2%, respectively. Also, at the receiver side, while RBNSiZeComm does not generate any saving, TSS and RZE produce about 36.9 and 12.5% savings on an average, respectively. Considering certain data types that may occur in the context of some wireless sensor networks (WSN) based applications (e.g., remote healthcare, agricultural WSNs, etc.), our simulation results demonstrate that for AWGN noisy channels, the transmitter side savings vary from about 33–50% on an average, while for RBNSiZeComm, this saving is about 33–61% on the same data set (Sinha in Proceedings of 6th IEEE consumer communications and networking conference (CCNC), Las Vegas, pp. 1–5, 2009). Thus, taking into account the low cost/complexity of the proposed transceiver, these results clearly establish that CNS can be a suitable candidate for communication in low power wireless sensor networks, such as in remote healthcare applications, body area networks, home automation, WSNs for agriculture and many others.     

Hierarchical geographic multicast routing for wireless sensor networks

Wireless sensor networks comprise typically dense deployments of large networks of small wireless capable sensor devices. In such networks, multicast is a fundamental routing service for efficient data dissemination required for activities such as code updates, task assignment and targeted queries. In particular, efficient multicast for sensor networks is critical due to the limited energy availability in such networks. Multicast protocols that exploit location information available from GPS or localization algorithms are more efficient and robust than other stateful protocols as they avoid the difficulty of maintaining distributed state (multicast tree). Since localization is typically already required for sensing applications, this location information can simply be reused for optimizing multicast performance at no extra cost. Recently, two protocols were proposed to optimize two orthogonal aspects of location-based multicast protocols: GMR (Sanchez et al. GMR: Geographic multicast routing for wireless sensor networks. In Proceedings of the IEEE SECON, 2006) improves the forwarding efficiency by exploiting the wireless multicast advantage but it suffers from scalability issues when dealing with large sensor networks. On the other hand, HRPM (Das et al. Distributed hashing for scalable multicast in wireless ad hoc networks. IEEE TPDS 47(4):445–487, 2007) reduces the encoding overhead by constructing a hierarchy at virtually no maintenance cost via the use of geographic hashing but it is energy-inefficient due to inefficacies in forwarding data packets. In this paper, we present HGMR (hierarchical geographic multicast routing), a new location-based multicast protocol that seamlessly incorporates the key design concepts of GMR and HRPM and optimizes them for wireless sensor networks by providing both forwarding efficiency (energy efficiency) as well as scalability to large networks. Our simulation studies show that: (i) In an ideal environment, HGMR incurs a number of transmissions either very close to or lower than GMR, and, at the same time, an encoding overhead very close to HRPM, as the group size or the network size increases. (ii) In a realistic environment, HGMR, like HRPM, achieves a Packet Delivery Ratio (PDR) that is close to perfect and much higher than GMR. Further, HGMR has the lowest packet delivery latency among the three protocols, while incurring much fewer packet transmissions than HRPM. (iii) HGMR is equally efficient with both uniform and non-uniform group member distributions.     

Channel-quality-aware multihop broadcast for asynchronous multi-channel wireless sensor networks

In this paper, we propose Multi-channel EMBA (M-EMBA), efficient multihop broadcast for asynchronous multi-channel wireless sensor networks. Our scheme employs two channel-quality-aware forwarding policies of improved forwarder’s guidance and fast forwarding to improve multihop broadcast performance. The improved forwarder’s guidance allows forwarders to transmit broadcast messages with guidance to their receivers through channels with good quality. The guidance indicates how each receiver should forward the broadcast message to its neighbor nodes. The improved forwarder’s guidance tremendously reduces redundant transmissions and collisions. Fast forwarding allows adjacent forwarders to send their broadcast messages simultaneously through different channels that have good quality, which helps to reduce multihop broadcast latency and improve multi-channel broadcast utility. In this work, we evaluate the multihop broadcast performance of M-EMBA through theoretical analysis of the system design and empirical simulation-based analysis. We implement M-EMBA in ns-2 and compare it with the broadcast schemes of ARM, EM-MAC, and MuchMAC. The performance results show that M-EMBA outperforms these protocols in both light and heavy network traffic. M-EMBA reduces message cost in terms of goodput, total bytes transmitted, as well as broadcast redundancy and collision. M-EMBA also achieves a high broadcast success ratio and low multihop broadcast latency. Finally, M-EMBA significantly improves energy efficiency by reducing average duty cycle.     

A bio-inspired field estimation scheme for wireless sensor networks

This paper proposes and analyzes a bio-inspired field estimation scheme using wireless sensor networks. The proposed scheme exploits the temporal pattern of the sensed process to reduce the number of samples sent back to the sink by a sensor node and, as consequence, decrease the energy consumption in data transmission. The proposed scheme is orthogonal to the techniques that reduce the spatial density of collected samples deactivating nodes with similar measurements. Thus, the proposed scheme can be used along with these techniques. We present two variations of this scheme: a sample-bounded and an error-bounded. The sample-bounded limits the maximum number of samples sent back to the sink, while the error-bounded guarantees the observation of every event of interest. Results show that for very regular processes the scheme can reduce up to 90% the total amount of samples sent in the network and even for less regular processes the proposed scheme can reduce the total amount of samples sent from approximately 10 up to 20%, with small reconstruction errors.     

IRS: application reconfiguration scheme for wireless sensor networks

Application reconfiguration is essential to achieving flexibility and adaptability of wireless sensor networks (WSNs) used in environment monitoring. In this paper, we present an integrated reconfiguration scheme (IRS) for implementing environment adaptive application reconfiguration (EAAR) in WSNs. In our scheme, application reconfiguration is implemented with the push‐based paradigm for densely distributed nodes and the cluster‐based hybrid reconfiguration (CHR) paradigm for sparsely distributed nodes. We demonstrate the energy‐efficiency and scalability of our scheme by analyzing the energy consumption based on a randomly deployed sensor network. Moreover, we derive the density threshold of reconfiguration nodes (RNs) for determining if the nodes are densely or sparsely distributed, and choose the mode of operation for IRS. We use extensive simulation experiments to demonstrate the effectiveness of our scheme. Copyright © 2009 John Wiley & Sons, Ltd.     

Energy-neutral scheduling and forwarding in environmentally-powered wireless sensor networks

In environmentally-powered wireless sensor networks (EPWSNs), low latency wakeup scheduling and packet forwarding is challenging due to dynamic duty cycling, posing time-varying sleep latencies and necessitating the use of dynamic wakeup schedules. We show that the variance of the intervals between receiving wakeup slots affects the expected sleep latency: when the variance of the intervals is low (high), the expected latency is low (high). We therefore propose a novel scheduling scheme that uses the bit-reversal permutation sequence (BRPS) – a finite integer sequence that positions receiving wakeup slots as evenly as possible to reduce the expected sleep latency. At the same time, the sequence serves as a compact representation of wakeup schedules thereby reducing storage and communication overhead. But while low latency wakeup schedule can reduce per-hop delay in ideal conditions, it does not necessarily lead to low latency end-to-end paths because wireless link quality also plays a significant role in the performance of packet forwarding. We therefore formulate expected transmission delay (ETD), a metric that simultaneously considers sleep latency and wireless link quality. We show that the metric is left-monotonic and left-isotonic, proving that its use in distributed algorithms such as the distributed Bellman–Ford yields consistent, loop-free and optimal paths. We perform extensive simulations using real-world energy harvesting traces to evaluate the performance of the scheduling and forwarding scheme.     

An optimized forwarding protocol for lifetime extension of wireless sensor networks

Optimized routing (from source to sink) in wireless sensor networks (WSN) constitutes one of the key design issues in prolonging the lifetime of battery‐limited sensor nodes. In this paper, we explore this optimization problem by considering different cost functions such as distance, remaining battery power, and link usage in selecting the next hop node among multiple candidates. Optimized selection is carried out through fuzzy inference system (FIS). Two differing algorithms are presented, namely optimized forwarding by fuzzy inference systems (OFFIS), and two‐layer OFFIS (2L‐OFFIS), that have been developed for flat and hierarchical networks, respectively. The proposed algorithms are compared with popular routing protocols that are considered as the closest counterparts such as minimum transmit energy (MTE) and low energy adaptive clustering hierarchy (LEACH). Simulation results demonstrate the superiority of the proposed algorithms in extending the WSN lifetime. Copyright © 2008 John Wiley & Sons, Ltd.     

无线网状网中基于信道预留的多信道媒体接入控制方案

目前多信道无线Mesh网络WMN(Wireless Mesh Network)的MAC(Medium Access Contro)l仍然存在信道利用率低的问题,因此提出了具有控制信道和数据信道的多信道WMN的MAC方案。方案采用数据信道预留机制来提高系统的吞吐量,并降低接入时延。该方案通过减小控制信道上的碰撞概率可以有效降低系统接入时延并提高控制信道的利用率。理论分析和性能估计表明此方案具有高的吞吐量和低的接入时延,性能明显优于现有的公共信道控制方案CCC(Common Control Channel)。     

A forwarding scheme for reliable and energy-efficient data delivery in cluster-based sensor networks

This letter proposes a novel forwarding scheme for reliable and energy-efficient data delivery in the cluster-based sensor networks. While multiple nodes in a cluster receive a packet, only one node among them is elected to send the acknowledgement back and then to broadcast it to the next cluster. With the binary exponential backoff algorithm for the election, the proposed scheme is more reliable and energy-efficient than existing forwarding schemes for the cluster-based sensor networks.     

TPGF: geographic routing in wireless multimedia sensor networks

In this paper, we propose an efficient Two-Phase geographic Greedy Forwarding (TPGF) routing algorithm for WMSNs. TPGF takes into account both the requirements of real time multimedia transmission and the realistic characteristics of WMSNs. It finds one shortest (near-shortest) path per execution and can be executed repeatedly to find more on-demand shortest (near-shortest) node-disjoint routing paths. TPGF supports three features: (1) hole-bypassing, (2) the shortest path transmission, and (3) multipath transmission, at the same time. TPGF is a pure geographic greedy forwarding routing algorithm, which does not include the face routing, e.g., right/left hand rules, and does not use planarization algorithms, e.g., GG or RNG. This point allows more links to be available for TPGF to explore more routing paths, and enables TPGF to be different from many existing geographic routing algorithms. Both theoretical analysis and simulation comparison in this paper indicate that TPGF is highly suitable for multimedia transmission in WMSNs.     

一种实用的DF协作无线传感器网络跨层设计

针对前向译码（DF）协作无线传感器网络的特点和要求,探讨基于分集合并和差错控制两种技术的实用跨层设计方案。首先,研究支持DF中继协议的协作传感器网络在目的节点采用等增益合并（EGC）的检测方案。通过和传统的最大比合并（MRC）方案以及最近提出的协作MRC方案综合比较,说明等增益合并是一个具有良好性能的实用方案。然后,把物理层的EGC和数据链路层的自动请求重传（ARQ）结合起来,再进行系统分析。最后,基于EGC和截断ARQ提出一种实用跨层设计方案。     

一种实用的DF协作无线传感器网络跨层设计

针对前向译码(DF)协作无线传感器网络的特点和要求,探讨基于分集合并和差错控制两种技术的实用跨层设计方案。首先,研究支持DF中继协议的协作传感器网络在目的节点采用等增益合并(EGC)的检测方案。通过和传统的最大比合并(MRC)方案以及最近提出的协作MRC方案综合比较,说明等增益合并是一个具有良好性能的实用方案。然后,把物理层的EGC和数据链路层的自动请求重传(ARQ)结合起来,再进行系统分析。最后,基于EGC和截断ARQ提出一种实用跨层设计方案。     

无线传感器网络的簇头功率控制技术

在军事侦察与环境监测中,无线传感器网络一般部署在无人区域或危险区域,不能依靠人对系统进行配置与管理.网络节点通过撒播造成分簇后密度不均,影响了网络性能.由于同簇节点通信使用同一信道,簇的大小直接关系到每个节点的通信能力.当簇内节点个数处于一个合适的范围时,网络才能发挥最好的性能.因此需要对簇头进行功率控制来优化网络结构.针对这一缺乏准确数学模型的过程,提出一种基于PID的模糊自适应的变步长簇头功率控制方案,把簇内节点数目控制在一个合理的范围内.其特点是概念简单、易于理解和提高系统的鲁棒性,仿真结果从理论上证明了通过控制分簇大小以后,网络的寿命和通信能力都有所增加.