Delay analysis for forward signaling channels in wireless cellularnetwork

We consider connection-oriented wireless cellular networks. Such second generation systems are circuit-switched digital networks which employ dedicated radio channels for the transmission of signaling information. A forward signaling channel is a common signaling channel assigned to carry the multiplexed stream of paging and channel-allocation packets from a base station to the mobile stations. Similarly, for ATM wireless networks, paging and virtual-circuit-allocation packets are multiplexed across the forward signaling channels as part of the virtual-circuit set-up phase. The delay levels experienced by paging and channel-allocation packets are critical factors in determining the efficient utilization of the limited radio channel capacity. A multiplexing scheme operating in a “slotted mode” can lead to reduced power consumption at the handsets, but may in turn induce an increase in packet delays. In this paper, focusing on forward signaling channels, we present schemes for multiplexing paging and channel-allocation packets across these channels, based on channelization plans, access priority assignments and paging group arrangements. For such multiplexing schemes, we develop analytical methods for the calculation of the delay characteristics exhibited by paging and channel-allocation packets. The resulting models and formulas provide for the design and analysis of forward signaling channels for wireless network systems. This revised version was published online in July 2006 with corrections to the Cover Date.     

Power Efficient Video Multipath Transmission over Wireless Multimedia Sensor Networks

This paper proposes a power efficient multipath video packet scheduling scheme for minimum video distortion transmission (optimised Video QoS) over wireless multimedia sensor networks. The transmission of video packets over multiple paths in a wireless sensor network improves the aggregate data rate of the network and minimizes the traffic load handled by each node. However, due to the lossy behavior of the wireless channel the aggregate transmission rate cannot always support the requested video source data rate. In such cases a packet scheduling algorithm is applied that can selectively drop combinations of video packets prior to transmission to adapt the source requirements to the channel capacity. The scheduling algorithm selects the less important video packets to drop using a recursive distortion prediction model. This model predicts accurately the resulting video distortion in case of isolated errors, burst of errors and errors separated by a lag. Two scheduling algorithms are proposed in this paper. The Baseline scheme is a simplified scheduler that can only decide upon which packet can be dropped prior to transmission based on the packet’s impact on the video distortion. This algorithm is compared against the Power aware packet scheduling that is an extension of the Baseline capable of estimating the power that will be consumed by each node in every available path depending on its traffic load, during the transmission. The proposed Power aware packet scheduling is able to identify the available paths connecting the video source to the receiver and schedule the packet transmission among the selected paths according to the perceived video QoS (Peak Signal to Noise Ratio—PSNR) and the energy efficiency of the participating wireless video sensor nodes, by dropping packets if necessary based on the distortion prediction model. The simulation results indicate that the proposed Power aware video packet scheduling can achieve energy efficiency in the wireless multimedia sensor network by minimizing the power dissipation across all nodes, while the perceived video quality is kept to very high levels even at extreme network conditions (many sensor nodes dropped due to power consumption and high background noise in the channel).     

Topology control in the presence of jammers for wireless sensor networks

In this paper, the problem of ensuring packet delivery ratio and high network lifetime in wireless sensor networks in the presence of single or multiple jammers is studied using single‐leader‐multiple‐followers Stackelberg game theory. A topology control scheme is proposed, in which the sink node, which acts as the leader, identifies the set of jamming affected nodes. On the other hand, the sensor nodes, which act as followers, need to decide an optimum transmission power level, while ensuring an optimal set of neighbor nodes covered. A scheme, named TC‐JAM, for ensuring packet delivery ratio, while avoiding jammers and increasing network lifetime in wireless sensor networks, is proposed. In existing literatures, the sensor nodes are envisioned to be equipped with multiple interfaces, while having access for multiple channels. However, in TC‐JAM, the sensor nodes have simple hardware with single interface for communication, ie, the sensor nodes have single channel for communication. Additionally, in the proposed scheme, TC‐JAM, each sensor node has a provision to vary its transmission power according to the chosen strategies. Using TC‐JAM, the energy consumption of the overall network reduces by up to 62%, and the network lifetime increases by 56% to 73%.     

BER-based Power Scheduling in Wireless Sensor Networks

In wireless sensor networks, there are many information exchanges between different terminals. In order to guarantee a good level of Quality of Service (QoS), the source node should be smart enough to pick a stable and good quality communication route in order to avoid any unnecessary packet loss. Due to the error-prone links in a wireless network, it is very likely that the transmitted packets over consecutive links may get corrupted or even lost. It is known that retransmissions will increase the overhead in the network, which in turns increase the total energy consumption during data transmission. In this paper, we focus on the Bit Error Rate (BER) during packet transmission and propose a power scheduling scheme to reduce the total energy consumption in the routing. Our approach controls the transmission power of each transmitter to achieve the minimum energy consumption for successful packet transmission. Considering the limited bandwidth resource, we also plan the multihop route while considering the BER and network load at the same time. The simulation results show that our approach can reduce the total energy consumption during data transmission.     

Distributed Flow Admission Control for Multimedia Services Over Wireless Ad Hoc Networks

In this paper we propose a novel Priority-based Distributed flow Admission Control (PDAC) protocol to provide Quality of Service (QoS) to multimedia applications over the Dynamic Source Routing (DSR) protocol-based wireless ad hoc networks. In contrast to short-term packet forwarding, medium and long-term multimedia and real-time traffic may benefit from ‘flow’-based transmission due to the reduction in the packet-level control overhead. In this paper, we introduce a new DSR option called the “Admission Control Option” for flow establishment, and present a new scalable transmission rate reservation protocol to support bandwidth-constrained traffic flows in interference-limited wireless ad hoc networks. It allows a node in the wireless ad hoc network to establish or discard a traffic flow state based on the global knowledge of traffic flow priority, and local knowledge in the form of interference and effective transmission rate. The PDAC scheme can also operate in a ‘cross-layer’ protocol architecture that encompasses the network layer and the MAC layer.     

An optimal resource control scheme under fidelity and energy constraints in sensor networks

To control congestion, either the traffic from sources should be “reduced” (traffic controlling) or the available resources should be “increased” (resource controlling). Compared to the wired and other wireless counterparts, wireless sensor networks usually have elastic resource availability, and the applications require a certain level of throughput called fidelity. As a result, resource control strategies cannot only alleviate congestion but also ensure the required fidelity level during congestion by accommodating higher incoming traffic. In this paper, we first attempt to formally define the resource control framework that adjusts the resource provisioning at the hotspot nodes during congestion. In an effort to find the optimal resource control under the fidelity and energy constraints, we present a resource increase and decrease algorithm called Early Increase/Early Decrease (EIED) that tries to adjust the effective channel capacity quickly to suit the incoming traffic volume in an energy-efficient manner, thereby increasing the fidelity level observed by the application. Under the energy-constrained optimization, we prove this algorithm incurs the lowest overhead of energy consumption for the given fidelity level that is required by the application. We also prove that the EIED algorithm performed in a distributed manner also lowers the energy consumption per packet at an end-to-end level. The effectiveness of the EIED algorithm is verified by simulations based on realistic sensor network configurations.

Dynamic Channel Allocation in Wireless Networks Using Adaptive Learning Automata

Single-channel based wireless networks have limited bandwidth and throughput and the bandwidth utilization decreases with increased number of users. To mitigate this problem, simultaneous transmission on multiple channels is considered as an option. In this paper, we propose a distributed dynamic channel allocation scheme using adaptive learning automata for wireless networks whose nodes are equipped with single-radio interfaces. The proposed scheme, Adaptive Pursuit learning automata runs periodically on the nodes, and adaptively finds the suitable channel allocation in order to attain a desired performance. A novel performance index, which takes into account the throughput and the energy consumption, is considered. The proposed learning scheme adapts the probabilities of selecting each channel as a function of the error in the performance index at each step. The extensive simulation results in static and mobile environments provide that the proposed channel allocation schemes in the multiple channel wireless networks significantly improves the throughput, drop rate, energy consumption per packet and fairness index—compared to the 802.11 single-channel, and 802.11 with randomly allocated multiple channels. Also, it was demonstrated that the Adaptive Pursuit Reward-Only (PRO) scheme guarantees updating the probability of the channel selection for all the links—even the links whose current channel allocations do not provide a satisfactory performance—thereby reducing the frequent channel switching of the links that cannot achieve the desired performance.     

Energy-efficient protocols for wireless networks with adaptive MIMO capabilities

Transmission power control has been used in wireless networks to improve the channel reuse and/or reduce energy consumption. It has been mainly applied to single-input single-output (SISO) systems, where each node is equipped with a single antenna. In this paper, we propose a power-controlled channel access protocol for MIMO-capable wireless LANs with two antennas per node. Our protocol, called E-BASIC, extends the classic CSMA/CA access scheme by allowing for dynamic adjustment of the transmission mode and the transmission power on a per-packet basis so as to minimize the total energy consumption. By transmission mode we mean one of the four possible transmit/receive antenna configurations: 1 × 1 (SISO), 2 × 1 (MISO), 1 × 2 (SIMO), and 2 × 2 (MIMO). Depending on the transmitter-receiver distance, any of the four modes can be the optimal one in terms of minimizing the total energy consumption. We study the performance of E-BASIC in both ad hoc and access point topologies. We also incorporate E-BASIC in the design of a power-aware routing (PAR) scheme that selects minimum-energy end-to-end paths. Our adaptive designs are first conducted assuming fixed-rate transmission, but later extended to multi-rate systems. To account for the energy-throughput tradeoff in our designs, we impose a constraint on the average packet delivery time. Simulations indicate that the proposed adaptations achieve a significant reduction in the overall energy consumption relative to non-adaptive MIMO systems.     

Routing with off-network control: a novel paradigm for scalable design in very large sensor networks

This paper presents a novel architectural solution to address the problem of scalable routing in very large sensor networks. The control complexities of the existing sensor routing protocols, both flat and with traditional hierarchy, do not scale very well for large networks with potentially hundreds of thousands of embedded sensor devices. This paper develops a novel routing solution Off-Network Control Processing (ONCP) that achieves control scalability in large sensor networks by shifting certain amount of routing functions “off-network”. This routing approach, consisting of “coarse grain” global routing, and distributed “fine grain” local routing is proposed for achieving scalability by avoiding network-wide control message dissemination. We present the ONCP architectural concepts and analytically characterize its performance in relation to both flat and traditional hierarchical sensor routing architectures. We also present ns2-based experimental results which indicate that for very large networks, the packet drop, latency and energy performance of ONCP can be significantly better than those for flat sensor routing protocols such as Directed Diffusion and cluster-based traditional hierarchical protocols such as CBRP.     

Adaptive Cluster-Based Data Collection in Sensor Networks with Direct Sink Access

Recently wireless sensor networks featuring direct sink access have been studied as an efficient architecture to gather and process data for numerous applications. We focus on the joint effect of clustering and data correlation on the performance of such networks. We propose a novel Cluster-based Data Collection scheme for sensor networks with Direct Sink Access (CDC-DSA), and provide an analytical framework to evaluate its performance in terms of energy consumption, latency, and robustness. In our scheme, CHs use a low-overhead and simple medium access control (MAC) conceptually similar to ALOHA to contend for the reachback channel to the data sink. Since in our model data is collected periodically, the packet arrival is not modeled by a continuous random process and, therefore, our framework is based on transient analysis rather than a steady state analysis. Using random geometry tools, we study how the optimal average cluster size and energy savings vary in a response to various data correlation levels under the proposed MAC. Extensive simulations for various protocol parameters show that our analysis is fairly accurate for a wide range of parameters. Our results suggest that despite the tradeoff between energy consumption and latency, both of which can be substantially reduced by proper clustering design.     

WSN中一种基于能量效率的协同中继传输方案

本文针对分簇无线传感器网络,提出了一种基于能量效率的协同中继传输方案,该方案中源簇头根据源到邻簇头之间的信道状态信息选择最优中继节点;协同传输数据时,目的节点接收到两个时隙的信号后进行最大比合并,并根据设定的接收信噪比门限范围在确认帧中给中继节点反馈功率调整信息,以减少重传次数或降低中继节点的发射功率,在不增加开销的情况下可以减少系统总的能量消耗。文章利用概率密度函数推导了基于部分信道状态信息选择中继协同的误符号率闭式表达式,最后通过蒙特卡洛仿真进行了验证。结果表明:误符号率的理论推导值与仿真值一致,在相同的接收信噪比门限时,本文所提方案能够明显提高系统的能效性。      

On the Minimization of Communication Energy Consumption of Correlated Sensor Nodes

Minimizing the sensor-node energy consumption is an important consideration when designing wireless sensor networks. In this paper, we focus on the energy consumption issues related to communication of data from correlated sensor nodes. An optimization algorithm is proposed for minimizing the overall energy consumption of the hardware and the physical link. We perform a detailed trade-off analysis of the circuit energy consumption, the transmission energy consumption, the transmission time, the modulation symbol size, and the channel coding rate, over a wide range of transmission distances and correlation values. Thus, a new optimized communication schedule with much lower energy consumption than our benchmark scheme of optimized uncorrelated uncoded transmission is obtained. Compared to this scheme, the total energy consumption may be reduced by more than 83.5% for a correlation value of 0.6 and a transmission distance of 100 m when using the results from the proposed optimization. This is significant with respect to increasing the lifetime of a wireless sensor network.     

Bounded end-to-end delay with Transmission Power Control techniques for rechargeable wireless sensor networks

Due to sporadic availability of energy, a fundamental problem in rechargeable wireless sensor networks is nodes have to adjust their duty cycles continuously. On the other hand, the energy harvested from surrounding environment usually is not enough to power sensor nodes continually. Therefore, the nodes have to operate in a very low duty cycle. These unique characteristics cause packet delivery latency is critical in Rechargeable WSNs. At the same time, energy storage device of a node is always limited. Hence, the node cannot be always beneficial to conserve energy when a network can harvest excessive energy from the environment. In this work, we introduce a scheme by improving transmission power of nodes to bound E2E delay. We provide an algorithm for finding the minimal sleep latency from a node to a sink by increasing minimal h number of nodes whose transmission power improved. For bounding E2E delay from source node to the sink, we propose an E2E delay maintenance solution. Through extensive simulation and experiments, we demonstrate our delay bound maintenance scheme is efficient to provide E2E delay guarantees in rechargeable wireless sensor networks.     

Energy Efficient Hybrid ARQ Scheme under Error Constraints

Due to the volatile characteristics of wireless channel and limited battery resource in the handheld devices, high throughput and energy efficiency are important criteria for the design of mobile communication protocols. This paper proposes an energy efficient error control scheme, which has on-demand quality of services for wireless data networks. This scheme can be utilized to accomplish the dual goals of reducing energy consumption and preserving quality of service over wireless links. It combines a simple power control scheme with a hybrid automatic repeat request strategy using rate-compatible punctured convolutional codes. In order to increase the system utility, the power and the coding rate for the data transmission are adjusted to match the channel variation. In case of frame error rate being constrained, such as 10^–6, thethroughput and utility are analysed and it is found that the proposed scheme outperforms the existing schemes that use only error control.     

基于改进蚁群算法的高能效WSN协作传输策略*

针对传统传感器网络分簇不均匀,数据传输能耗相对较高的问题,提出了I-CoopACO(Cooperative transmission scheme based improved Ant Colony Optimal algorithm)算法.该算法在协作LEACH (Low Energy Adaptive Clustering Hierar-chy)的技术基础上,改进了成簇过程,使得分簇规模更加均匀;在稳定传输阶段,利用节点剩余能量和传输功耗构建启发因子,通过改进的蚁群算法搜索下一跳中继节点获得最优节点,使得传输功耗更低,能耗更均衡.仿真结果表明,在随机分布的感知网络中,I-CoopACO算法减少了传输能耗,均衡了网络负载,延长了网络工作寿命,比协作LEACH算法延长了64.93％的工作寿命.     

Energy‐aware geographic routing in wireless sensor networks with anchor nodes

Energy efficiency has become an important design consideration in geographic routing protocols for wireless sensor networks because the sensor nodes are energy constrained and battery recharging is usually not feasible. However, numerous existing energy‐aware geographic routing protocols are energy‐inefficient when the detouring mode is involved in the routing. Furthermore, most of them rarely or at most implicitly take into account the energy efficiency in the advance. In this paper, we present a novel energy‐aware geographic routing (EAGR) protocol that attempts to minimize the energy consumption for end‐to‐end data delivery. EAGR adaptively uses an existing geographic routing protocol to find an anchor list based on the projection distance of nodes for guiding packet forwarding. Each node holding the message utilizes geographic information, the characteristics of energy consumption, and the metric of advanced energy cost to make forwarding decisions, and dynamically adjusts its transmission power to just reach the selected node. Simulation results demonstrate that our scheme exhibits higher energy efficiency, smaller end‐to‐end delay, and better packet delivery ratio compared to other geographic routing protocols. Copyright © 2011 John Wiley & Sons, Ltd.     

An energy efficiency model for adaptive and custom error control schemes in Bluetooth sensor networks

This paper analyzes the effect of custom error control schemes on the energy efficiency in Bluetooth sensor networks. An analytical model is presented to evaluate the energy efficiency metric, which considers in just one parameter the energy and reliability constraints of wireless sensor networks. New packet types are introduced using some error control strategies in the AUX1 packet, where custom coding can be implemented. Two adaptive techniques are proposed that change the error control strategy based on the number of hops traversed by a packet through the network. A packet selection strategy based on channel state is proposed for sensor networks with different channel conditions. Performance results are obtained through analysis and simulation in Nakagami-m fading channels for networks with different number of hops and channel conditions.     

Performance evaluation of packet aggregation scheme for VoIP service in wireless multi-hop network

In a wireless multi-hop network environment, energy consumption of mobile nodes is an important factor for the performance evaluation of network life-time. In Voice over IP (VoIP) service, the redundant data size of a VoIP packet such as TCP/IP headers is much larger than the voice data size of a VoIP packet. Such an inefficient structure of VoIP packet causes heavy energy waste in mobile nodes. In order to alleviate the effect of VoIP packet transmission on energy consumption, a packet aggregation algorithm that transmits one large VoIP packet by combining multiple small VoIP packets has been studied. However, when excessively many VoIP packets are combined, it may cause deterioration of the QoS of VoIP service, especially for end-to-end delay. In this paper, we analyze the effect of the packet aggregation algorithm on both VoIP service quality and the energy consumption of mobile nodes in a wireless multi-hop environment. We build the cost function that describes the degree of trade-off between the QoS of VoIP services and the energy consumption of a mobile node. By using this cost function, we get the optimum number of VoIP packets to be combined in the packet aggregation scheme under various wireless channel conditions. We expect this study to contribute to providing guidance on balancing the QoS of VoIP service and energy consumption of a mobile node when the packet aggregation algorithm is applied to VoIP service in a wireless multi-hop networks.     

物联网感知层多路径传输策略研究

多路径数据传输是无线传感器网络亟需解决的一个关键问题.本文针对节点故障、链路失效和外界干扰影响网络稳定性和可靠性,提出一种基于混合蛙跳算法的无线传感器网络多路径传输策略.首先我们详细介绍了蛙跳算法及其原理,之后我们将其应用到无线传感器网络多路径传输策略之中,接着运用混合蛙跳算法对传感网络节点其进行更新、划分、重组以便选择出最优节点建立传输最优路径,提高网络的稳定性和可靠性.通过算法仿真与结果对比提出的算法与AODV、粒子群PSO算法相比,在网络能耗、传输时延、丢包率、连通率和可靠度等方面都具有较好的性能.其中网络能耗比AODV、PSO算法降低了62.5％和35.8％.     

Predictive Congestion Control Protocol for Wireless Sensor Networks

Available congestion control schemes, for example transport control protocol (TCP), when applied to wireless networks, result in a large number of packet drops, unfair scenarios and low throughputs with a significant amount of wasted energy due to retransmissions. To fully utilize the hop by hop feedback information, this paper presents a novel, decentralized, predictive congestion control (DPCC) for wireless sensor networks (WSN). The DPCC consists of an adaptive flow and adaptive back-off interval selection schemes that work in concert with energy efficient, distributed power control (DPC). The DPCC detects the onset of congestion using queue utilization and the embedded channel estimator algorithm in DPC that predicts the channel quality. Then, an adaptive flow control scheme selects suitable rate which is enforced by the newly proposed adaptive backoff interval selection scheme. An optional adaptive scheduling scheme updates weights associated with each packet to guarantee the weighted fairness during congestion. Closed-loop stability of the proposed hop-by-hop congestion control is demonstrated by using the Lyapunov-based approach. Simulation results show that the DPCC reduces congestion and improves performance over congestion detection and avoidance (CODA) [3] and IEEE 802.11 protocols.