Peter Ball

Extending the lifetime of multi hop ad hoc networks by managing the use of relay nodes

Multi hop ad hoc networks rely on the cooperation between nodes to relay information between a source and destination. Depending on their location, some nodes may be better placed than others to offer a relay function and this may lead to early exhaustion of the battery energy of these nodes. To address this problem, this paper investigates the use of a battery capacity threshold to protect overused nodes and maximise the lifetime of the network. The network lifetime is evaluated as a function of the threshold level using a 25 node network model. The results of the model show that if the threshold level is high, this leads to route blockage. Conversely if the threshold is too low then the more heavily used nodes will rapidly exhaust the battery capacity. The optimum threshold level is found to be approximately 30% of the maximum battery capacity, giving an improvement in the network lifetime of about 78%.

A ground level radio propagation model for road-based wireless sensor networks

This paper investigates the use of a wireless sensor network (WSN) for communicating between road-based nodes. These nodes are situated at ground level and two-way wireless communication is required between the nodes and from the nodes to a roadside control unit. Measurements have been carried out to examine the propagation close to the ground to determine the maximum distance between road-based nodes as a function of the antenna height. The results show that for a frequency of 2.4 GHz, a range of up to 8m is achievable with 2mW EIRP. An empirical near-ground level radio propagation model is derived and the predicted results from this model are shown to match closely to the measured results.

Energy efficiency metrics for low-power near ground level wireless sensors

This paper proposes green energy efficiency metrics for low-power wireless sensors operating at ground level. The metrics are derived from our previous work on energy efficiency analysis for general wireless networks and a radio propagation model for near ground level wireless sensors. A numerical analysis is carried out to investigate the utilization of the green energy efficiency metrics for ground level communication in wireless sensor networks. The proposed metrics have been developed to calculate the optimal sensor deployment, antenna height and energy efficiency level for the near ground wireless sensor. As an application of the proposed metrics, the relationship between the energy efficiency and the spacing between the wireless sensor nodes is studied. The results provide an accurate guidance for energy efficient deployment of near ground level wireless sensors.

A shim layer for heterogeneous wireless communications scheduling in intelligent transport systems

Given the future context of fully integrated Intelligent Transport Systems, reliable wireless communications is a necessity. Traditionally, a single wireless technology is selected for communication but by using heterogeneous wireless communication, advantage can be taken of the different transmission characteristics. This paper proposes a novel Multiple Interface Scheduling Algorithm (MISA) which schedules uplink packets over multiple technologies for which no coordination is required among access networks. The algorithm incorporates a dynamic scoring approach for each of the available networks based on selected system performance parameters. A key feature of the proposed scheduler is that it is located between the IP layer and the MAC layer, hence a single IP address is used, and it is not necessary to modify the wireless standards. A model has been developed to simulate the proposed algorithm and the system performance for three multi radio transmission diversity schemes. The results show the advantage that can be gained in throughput by cooperatively using multiple technologies.

Multiple Interface Scheduling System for HeterogeneousWireless Vehicular Networks: Description and Evaluation

Reliable wireless communications between vehicles (V2V) and between vehicles and infrastructure (V2I) will play a key role in future transport networks. Where there is overlapping coverage of multiple Radio Access Technologies, with no cooperation between them, a vehicle can use the different technologies simultaneously. This paper proposes an uplink Multi Interface Scheduling System (MISS) located at an intermediate shim layer on the user side, to achieve efficient bandwidth aggregation, or lower end-to-end packet delay. MISS aims to find all the available networks that can meet multiple criteria based on user preference and required performance. Simulation results show that safety critical traffic can be prioritized where the resources are insufficient for all the services. Video delivery quality is also improved by prioritizing the most important frames. This algorithm is ideally suited to vehicular networks, where delivery of safety traffic and/or video is an essential requirement. Received on 18 February 2016; accepted on 29 February 2016; published on 10 January 2017

Mobility and Network Selection in Heterogeneous Wireless Networks: User Approach and Implementation

The Intelligent Transport Systems (ITS) wireless infrastructure needs to support various safety and non-safety services for both autonomous and non-autonomous vehicles. The existing wireless infrastructures can already be used for communicating with different mobile entities at various monetary costs. A packet scheduler, included in a shim layer between the network layer and the medium access (MAC) layer, which is able to schedule packets between uncoordinated Radio Access Technologies ( RATs ) without modification of the wireless standards, has been devised and its performance evaluated. In this paper, we focus on the influence of mobility type in heterogeneous wireless networks. Three cases are considered based on the mobility in the city: walking, cycling, and driving. Realistic simulations are performed by generating mobility traces of Oxford from Google Maps and overlaying the real locations of existing WiFi Access Points.xa0 Results demonstrate that the shim layer approach can accommodate different user profiles and can be a useful abstraction to support Intelligent Transport Systems where there is no coordination between different wireless operators.

Performance Evaluation of Dynamic Scheduler in Multiple Queue Shim Layer for Heterogeneous Vehicular Communications

Reliable wireless communications between vehicles (V2V) and between vehicles and infrastructure (V2I) will play a key role in future transport networks. Where there is overlapping coverage of multiple Radio Access Technologies, with no cooperation between them, a vehicle can use the different technologies simultaneously to enhance performance and improve resilience. This paper proposes an uplink Multi Interface Scheduling System (MISS) that incorporates intelligent interface selection, located at an intermediate shim layer on the user side, to achieve efficient bandwidth aggregation, or lower delay. The data can be sent on multiple technologies simultaneously or separately based on user preference and required performance. Rather than finding the best alternative amongst different technologies, this papers algorithm aims to find all the available networks that can meet multiple criteria. Simulation has been carried out to determine the performance of the system in the presence of a range of different service types. The simulation results show that safety critical traffic can be prioritized in terms of throughput and delay where the resources are insufficient for all the services. This algorithm is ideally suited to vehicular networks, particularly where delivery of safety traffic is an essential requirement.

Analysis of fixed and mobile sensor systems for parking space detection

This paper analyses the relative merits of fixed and mobile sensor solutions for monitoring street car parking availability. A fixed sensor solution requires placement of sensors under each allocated parking space. The mobile approach uses a ranger mounted on a moving vehicle which continuously monitors the presence of parked cars and spaces. One of the challenges of the mobile sensor solution is to account for the variability of the position of the vehicle across the road. This paper proposes a dual detector solution using sonar and lidar together with differential detection system to mitigate the uncertainty.

Heterogeneous wireless system testbed for remote image processing in automated vehicles

Automated vehicles will carry computing and communication platforms, and will have enhanced sensing capabilities. Safety around people along with obstacle detection and avoidance systems are key to their success. In controlled environments, automated vehicles can benefit from a remote processing approach to reduce cost and accelerate deployment on larger scales. In this paper we present a section of our intelligent transport systems testbed which evaluates the remote image processing approach with a novel heterogeneous wireless communication system. Hardware implementation is carried out for an experimental evaluation and comparison with the simulation results.

Routing in wireless ad hoc networks jointly optimized for minimum transmission power and maximum network lifetime

Wireless ad hoc networks are being deployed in a wide range of applications and many of these networks use battery operated nodes. A key requirement for these networks is to maximize the time span when all nodes have sufficient battery charge to participate in communication with other nodes. To meet this requirement, this paper describes a routing strategy that seeks to find the best balance between minimizing the power consumption and evenly using all nodes within the network to avoid early exhaustion of individual nodes. The proposed scheme is compared to reported schemes using minimum power routing and the results show that the proposed scheme gives a longer time until the first nodes battery energy is depleted with a lower network power consumption than schemes using just energy minimization.