A Heuristic Relay Positioning Algorithm for Heterogeneous Wireless Networks

An adaptive cuckoo search based algorithm for placement of relay nodes in wireless body area networks

A wireless sensor network (WSN) is composed of many low cost sensor nodes that can perform sensing, simple computation, and short range communications. To maximize the life time of a WSN, relay nodes are placed to perform communication. In the single-tiered relay node placement problem, the sensor nodes can also participate in the forwarding of the packets of other nodes. In the two-tiered relay node placement problem, only the relay nodes forwards the packets from other nodes. In this talk, we will present the state of the art in the area of relay node placement, ranging from coverage to connectivity and to survivability, and from unconstrained problem to constrained problem. In most cases, efficient approximation algorithms are known.

Relay node placement preserving coverage and connectivity is an important problem for the deployment of a fault tolerant two tier wireless sensor network (WSN). In this paper, we propose an algorithm for relay node placement that ensures k-coverage of the sensor nodes and s-connectivity of the relay nodes within the network. The basic goal of the algorithm is to optimize the network cost by using least number of relay nodes. This is carried out by reducing the overlapped coverage area of the relay nodes. The algorithm is based on the spiral traversal of sensor nodes, which is generated by using Jarvis March approach. The proposed algorithm runs in $$O(n^{2})$$ time for n sensor nodes and is shown to be a 1.5-approximation algorithm. It is equally efficient for different and unequal degree of coverage and connectivity in the target area. The algorithm is experimented through the simulation run for different scenarios of WSN. The experimental results are then compared with some existing algorithms to demonstrate its effectiveness.

Wireless networks that operate on batteries are imposed with energy constraints and long distance communications between nodes are not desirable. Implementing relay nodes can improve network capacity and save communication energy. A two-hop relay routing scheme is considered, in which the relay nodes are temporarily placed and have energy constraints. This paper investigates a joint optimization problem on relay node placement and route assignment for two-tiered wireless networks. A recursive weighted clustering binary integer programming (WCBIP) algorithm is proposed to maximize the total number of information packets received at the BS during the network lifetime. We first present an optimization algorithm based on binary integer programming (BIP) for relay node assignment with the current node locations. Subsequently, a weighted clustering algorithm is applied to move the relay nodes to the best locations to best serve their respectively associated edge nodes. The algorithm has the complexity of O(2n). The simulation results show that the proposed algorithm has significantly better performance than the other two relay placement schemes. Both theoretical analysis and practical design procedures are also presented with details.

Relay node placement in wireless sensor networks has potential application value in terms of establishing connected topologies, reducing data latency, and prolonging network life time. This paper studies the relay node placement problem which opts to deploy the optimum number of relay nodes into single-tiered WSN to meet network connectivity. We firstly draw on ideas of Delaunay Triangle and Voronoi Graph to construct neighbor components, then optimize the placement algorithm by means of Spanning tree and Steiner heuristic, finally combine all connected components for connectivity. The experiments show that our proposed algorithm can outperform other algorithms in terms of the number of relay nodes and average hop count with a reasonable time complexity.

In 2tWSN(two-tiered wireless sensor network), relay nodes are responsible for delivering the sensed data from sensor nodes to base stations. From the perspective of business, it needs more relay nodes to ensure network connectivity. From the perspective of economy, relay nodes are relatively expensive, so people are intended to place a minimum number of relay nodes while guaranteeing the data collecting and delivering. In this paper, we firstly model fault tolerant RNP(relay node placement) problem in 2tWSN as a graphic problem, denoted by DBY-HCG. It distinguishes relay nodes from base stations. Secondly, we figure out keCi-RNPB algorithm. Moreover, an approximation algorithm aiming at finding the minimum length of k-vertex disjoint paths in connected sub-graph is raised up to support our algorithm's extensibility. Our algorithm is also the first solution for constrained version of fault tolerant relay node placement problem in 2tWSN. Extensive experiments have been executed in both unconstrained and constrained situations and the numeric results show that our solution is close to optimal solution.

Node placement for connected target coverage in wireless sensor networks with dynamic sinks

Hybrid <span>wireless networks (HWNs) are resulted from the integration of a mobile Ad hoc networks (MANET) and an infrastructure wireless networks. These networks have received increasing interest from researchers for their superior performance and reliability. Packet routing protocols in hybrid wireless networks are important to increase the capacity and scalability of these networks, therefore, several routing protocols have been proposed. Routing protocols in HWNs are designed and implemented from combining <span>the cellular transmission mode with the Ad hoc transmission mode. To route a message to the intended recipient of the sender, hybrid wireless networks use multi-hop technology. However, the source node needs relay nodes, which may be either adjacent nodes or base stations depending on set of parameters like bandwidth, load balancing, or the nearest node. This paper explores routing protocols for hybrid wireless networks and the techniques to enhance the security, performance, and capacity of these routing protocols.</span></span>

A new multi-rat scheduling algorithm for heterogeneous wireless networks

There is an increasing demand for high bandwidth-consuming services such as real-time video and video streaming over wireless access networks. A single radio access technology (RAT) in a heterogeneous wireless network may not always have enough radio resource to admit high bandwidth-consuming calls, such as video calls. Existing joint call admission control (JCAC) algorithms designed for heterogeneous wireless networks block/drop an incoming call when none of the available individual RATs in the network has enough bandwidth to admit the incoming call. Consequently, video calls experience high call blocking/dropping probability in the network. However, some calls such as multi-layer coded (scalable) video can be transmitted/received over one or multiple RATs. This article proposes a JCAC algorithm that selects a single or multiple RATs for scalable video calls in heterogeneous wireless networks, depending on availability of radio resources in available RATs. Non scalable calls are always admitted into a single RAT by the algorithm. The aim of the proposed algorithm is to reduce call blocking/dropping probability for both scalable and non-scalable calls. An analytical model is developed for the proposed JCAC algorithm, and its performance is evaluated. Simulation results show that the proposed algorithm reduces call blocking/dropping probability in heterogeneous wireless networks.

Modern network technologies first evolved in wired networks and subsequently entered the wireless network field. Applications may work in pure wired network, pure wireless network or hybrid network. Improving performance in these network infrastructures has been a continuous effort for decades. In this dissertation, we tackle two important challenges: (1) improving handover performance in heterogeneous wireless network, and (2) improving TCP performance in multi-hop wireless network. In heterogeneous network, users expect uninterrupted services moving from one network to another. IEEE proposed Media Independent Handover (MIH) to make it possible to achieve better handover performance. Currently, Mobile IPv4 (MIP) is the dominant mechanism for mobility management and is expected to persist into the future. However, when multiple interfaces of a mobile client are connected to a Foreign Agent (FA), MIP and its existing improvements do not perform well when the active interface fails unexpectedly. In this dissertation, we propose novel mechanism and MIP extension with MIH support. We prove experimentally that the new approach eliminates the FA-HA latency and achieves much faster handover, compared with existing mechanism. Our method also allows FA-bicasting, which can improve transmission reliability by combining traffic from different links, through the same FA. In multi-hop wireless networks, the main network factor that affects TCP performance is the medium-access contention, complicated by other factors like hidden terminal. We analyze the TCP congestion window and provide a more accurate estimate of its optimal value than those reported in the prior work. We also show that the much shorter TCP-ACK packets consume comparable channel capacity as the much longer data packets. We therefore propose two methods to improve TCP throughput, as follows. (1) Segregate the flows of data and ACK using static routing in grid wireless network, (2) Develop an improved variant of delayed TCP ACK by minimizing the number of ACK packets. Our evaluation validates the effectiveness of the proposed method, which can enhance TCP performance significantly. In terms of throughput, it achieves up to 204% improvement over the regular TCP in chain-topology wireless networks, and about 35% improvement in a complex grid wireless network. We also propose a new architecture to achieve higher throughput when multiple TCP connections exist.

Due to adverse effects of hostile deployment environment(s), sensors nodes (SNs) deployed in the network may drain or get damaged. This attributes for loss of connectivity between the sensors and the sink node. Hence it is necessary to design the wireless sensor network (WSN) in a manner that the network is capable of coping up with the failure of few nodes/links. Using single hop data communication model reduces the lifetime of the network as the SNs are resource constrained (in terms of battery). Relay nodes (RNs) facilitate in improving network lifetime, fault tolerance and/or connectivity. Finding minimum number of relay nodes for a fault tolerant, fully connected network is a NP Hard problem. In this paper, we follow two phase relay node placement procedure to achieve the objective. In the first phase, we cluster the SNs using mean shift algorithm and place RNs as the cluster heads. In the second phase, we use metaheuristic algorithms like Moth Flame Optimization (MFO), Differential Evolution (DE), Bat algorithm (BA) and Biogeography Based Optimization algorithm (BBO) to place the RNs such that the required fault tolerance is achieved along with fully connected network. Extensive simulation results prove that MFO algorithm performs better for fault tolerant relay node placement problem.

The objective of the Hybrid Wireless Network with dedicated Relay Nodes (HWN*) proposal is to interface the Base Station (BS) Oriented Mobile Network (BSON) and the 802.11X assisted Mobile Ad hoc Wireless Network (MANET) so that one system can be utilised as an alternative radio access network for data transmissions, while the incorporation of the Relay Node (RN) is to extend the communication coverage, optimise medium resource sharing, increase spatial reuse opportunity, stabilise MANET link and create more micro-cells. The HWN* keeps the existing cellular infrastructure and a end-user Mobile Terminal (MT) can borrow radio resources from other cells through secured multi-hop RN relaying, where RNs are placed at pre-engineered locations. The main contribution of this work is the development of a HWN* system framework and related medium access and routing protocols/algorithms. The framework dedicatedly addresses the transparent multiple interface traffic handover management, cross layer routing, RN positioning and network topology issues to increase communication system capacity, improve Quality of Service (QoS), optimise transmission delay and reduce packet delivery delay.

The ever increasing user QoS demands and emergence of new user applications make job of network operators and manufacturers more challenging for efficiently optimisation and managing radio resources in radio the radio resources pools of different wireless networks. A group of strategies or mechanisms which are collectively responsible for efficient utilisation of radio resources available within the Radio Access Technologies (RAT) are termed as Radio Resource Management (RRM). The traditional RRM strategies are implemented independently in each RAT, as each RRM strategy considers attributes of a particular access technology. Therefore traditional RRM strategies are not suitable for heterogeneous wireless networks. Common Radio Resource Management (CRRM) or joint radio resource management (JRRM) strategies are proposed for coordinating radio resource management between multiple RATs in an improved manner. In this paper a fuzzy algorithm based CRRM strategy is presented to efficiently utilise the available radio resources in heterogeneous wireless networks. The proposed CRRM strategy balances the load in heterogeneous wireless networks and avoids the unwanted congestion situation. The results such as load distribution, packet drop rate and average throughput at mobile nodes are used to demonstrate the benefits of load balancing in heterogeneous wireless networks using proposed strategy.

Multi-hop cellular networks: Architecture and protocols for best-effort and real-time communication