The impact of physical conditions on network connectivity in wireless sensor network

In Wireless Sensor Networks, end-to-end routing paths need to be established when nodes want to communicate with the desired destination. For nodes assumed to be static, many routing protocols such as Directed Diffusion have been proposed to meet this requirement efficiently. The performance of such routing protocols is relative to the given network connectivity. This paper addresses mobile sensor nodes taking into account the diversity of scattered node density and investigates how physical conditions impact on network connectivity which in turn influences routing performance. Three analysis metrics: path availability, path duration, and interavailable path time are proposed to quantify the impact of different physical conditions on network connectivity. Simulation results show that the network connectivity varies significantly as a function of different physical conditions

Analysis and Validation of The Effect of Various Queueing Configurations to the End-to-end Throughput of Multi-Hop Wireless Network

A multi-hop wireless network is created by connecting multiple wireless access points (APs) as the backhaul of the network to increase the network coverage. The issue of spatial bias, unbalanced network performance of end-to-end throughput and delay occurs when the total offered load of the associated stations to the backhaul exceeds the wireless link capacity. Station associated to the access point with more hops away from the gateway will experience a significant amount of delay and lower end-to-end throughput compared to the station with fewer hops to the gateway. The equality of local successful transmit probability and mesh successful transmit probability in congested APs, which is the main root cause of the spatial bias problem, is modelled and validated. If the packet arrival ratio of local over mesh ingress interface is larger than the respective queue length ratio, the mesh ingress interface successful transmit probability will be higher than the local ingress interface successful transmit probability and vice-versa. By controlling the ratio of queue lengths, stations associated to the access point with more hops away from the gateway are given higher transmit opportunity, and therefore the spatial bias problem in multi-hop wireless network can be alleviate

Elastic fair rate allocation scheme for multi-radio wireless mesh networks

Fair bandwidth distribution among users remains a persistence issue in Wireless Mesh Networks (WMNs). Users which are more hops away from the gateway generally suffer from higher throughput degradation and hence higher delay. This is mainly due to the nature of IEEE 802.11 protocol, i.e. its operation in contention mode. In this paper, we propose a practical network-layer solution to address this fairness issue in Multi-Radio WMNs. The proposed framework consists of two main components: 1) lightweight messaging system and 2) Elastic fair Rate Allocation Scheme for Mesh Stations (ERASMeS). A highlight of the proposed solution is that it does not require any alteration of existing MAC and routing mechanisms and can be applied to nodes with multiple radio interfaces. This capability distinguishes it from other similar work on fairness provisioning in WMNs. The results obtained from our test-bed show that the proposed solution achieves a high degree of improvement in terms of end-to-end throughput and fairness index for all users

Policy based mobility and flow management for IPv6 heterogeneous wireless networks

We propose a dynamic mobility management framework for Internet Protocol version 6 (IPv6) and policy enforcement enabled heterogenous wireless networks. Policies and policy rules are defined depending on network infrastructure facilities, service agreements and negotiation results. Each traffic is coupled with an identifiable traffic flow while the heterogenous interface flowbindings are regulated by polices. The network selection, flow distribution, handovers and mobility procedures are flexible and we propose to improve the decision making viaMultiple Attributes Decision Making (MADM). Techniques considered in the framework include the IPv6 based Network Mobility (NEMO), multihoming capability, transparent vertical handovers, horizontal handovers and dynamic policy enforcement matching process to improve the Quality of Service (QoS), Quality of Experience (QoE) and ubiquitous connectivity. A experiment testbed and simulation models have been constructed to verify the mobility framework performance in a heterogeneous WiFi, WiMax and UMTS hybrid environment

Application of reinforcement learning to wireless sensor networks: models and algorithms

Wireless sensor network (WSN) consists of a large number of sensors and sink nodes which are used to monitor events or environmental parameters, such as movement, temperature, humidity, etc. Reinforcement learning (RL) has been applied in a wide range of schemes in WSNs, such as cooperative communication, routing and rate control, so that the sensors and sink nodes are able to observe and carry out optimal actions on their respective operating environment for network and application performance enhancements. This article provides an extensive review on the application of RL to WSNs. This covers many components and features of RL, such as state, action and reward. This article presents how most schemes in WSNs have been approached using the traditional and enhanced RL models and algorithms. It also presents performance enhancements brought about by the RL algorithms, and open issues associated with the application of RL in WSNs. This article aims to establish a foundation in order to spark new research interests in this area. Our discussion has been presented in a tutorial manner so that it is comprehensive and applicable to readers outside the specialty of both RL and WSNs

Throughput analysis of IEEE802.11n using OPNET

The aim of this paper is to evaluate the throughput performance of IEEE802.11n WLANs using a well-known commercial simulator called OPNET Modeler. We study the effects of IP packet size, Modulation and Coding Scheme (MCS), Channel Bonding, number of MIMO spatial streams, Block Acknowledgement (BA) and Type of Service (ToS)/Access Category (AC) on maximum throughput and Throughput Efficiency (TE). The impact of multiple users' access on TE is also analyzed. From these studies we offer fresh insights on underlying configurations and operating conditions which affect the peak throughput performance and efficiency of IEEE802.11n system

Antenna and base-station diversity for WSN livestock monitoring

Antenna and base-station diversity have been applied to a wireless sensor network for the monitoring of live-stock. A field trial has been described and the advantage to be gained in a practical environment has been assessed

Practical considerations for wireless sensor networks in cattle monitoring applications

The paper presents an investigation into wireless sensor networks (WSNs) for cattle monitoring. The proposed solution fulfils the requirement for intensive condition monitoring of individual animals, aggregation and timely reporting of data to the farm manager. The core contribution of this study is a wireless communication solution designed for both loose house dairy cattle and free ranging beef cattle. The design target utilises inexpensive, low power consumption sensor nodes as the base elements of a data gathering and communication infrastructure. This platform facilitates real-time data download for loose housed dairy cattle and non real-time communication for free ranging beef cattle where the former is more challenging. In order to meet the target objectives, both the hardware and software are designed to adapt to the deployment challenges which include mobility, radio path interference, short transmission range of sensor nodes and limited resources in terms of energy and storage. These challenges have been analysed and addressed. Laboratory experiments and farm trials have been carried out to evaluate the performance of the platform communication protocol. The results of experiments demonstrate that the platform performs efficiently while conforming to the limitations associated with WSN implementations

An investigation of vegetation effect on the performance of IEEE 802.11n technology at 5.18 GHz

In this paper, the performance of IEEE 802.11n Wi-Fi technology at 5.18 GHz frequency in one of the rural areas in Malaysia, which is typically covered by dense tropical foliage, is evaluated and analyzed. To our best knowledge, studies on the performance of the IEEE 802.11n technology in foliage area have not been fully explored. We have conducted line-of-sight and non-line-of-sight measurements through the tropical foliage using directional high gain antennas to determine the throughput and other well-known performance metrics. It is observed that by utilizing the key features of 802.11n such as channel bonding and short guard interval, superior performance results can be achieved for both aforementioned situations. Precise correlation of utilized hardware specification and acquired results in different points is another aspect of this work. The findings are useful for future rural wireless deployment particularly with low height antenna using IEEE 802.11n technology