Directional Antenna Model Research Articles

Performance Analysis of Statistical Priority-Based Multiple Access Network With Directional Antennas

This letter proposes an analytical framework to assess the network performance of a wireless network adopting statistical priority-based multiple access (SPMA) scheme with nodes equipping with directional antennas. By taking into account the spatial randomness of nodes and the impact of directional antenna, we first derive the analytical expressions of medium access probability (MAP), burst success probability, and packet success probability with tools from stochastic geometry. We then verify the correctness of the analytical framework by adopting three typical directional antenna models. By comparing with the scenario where nodes are equipped with omnidirectional antennas, we show the superiority of the directional antennas in limiting the aggregated network interference and enhancing the packet success probability.

Capacity of Vehicular Ad Hoc Networks Based on Multibeam Directional Transmission

The development of multibeam directional transmission technology used in vehicular ad hoc networks is drawing much more attention in recent years due to its wider coverage ability than omnidirectional transmission. In this paper, we analyse the transport capacity of the vehicular network using different antenna modes in the transmitter and receiver end, respectively. We first construct the cross‐layer model comprising the characteristic of the directional antenna model, arbitrary network model, and interference model. Then, based on scaling laws, we calculate the upper and lower bound of the network capacity with and without the directional multibeam transmission technology. In order to reduce the capacity lower bound computation complexity, several topology frameworks are constructed while taking various interferences into account included in the actual project. Finally, we analyse the capacity under changes of different parameters and also evaluate the law of capacity changes to discover how much improvement multibeam transmission technology can bring to the network performance. Analysis shows that compared with DTOR and OTDR mode, DTDR mode can continue to increase network capacity by 2 to 3 times on the basis of the above two modes.

On the Tradeoffs Between Coverage Radius, Altitude, and Beamwidth for Practical UAV Deployments

Current studies on unmanned aerial vehicle (UAV) based cellular deployment consider UAVs as aerial base stations for air-to-ground communication. However, they analyze UAV coverage radius and altitude interplay while omitting or over-simplifying an important aspect of UAV deployment, i.e., effect of a realistic antenna pattern. This paper addresses the UAV deployment problem while using a realistic three-dimensional directional antenna model. New tradeoffs between UAV design space dimensions are revealed and analyzed in different scenarios. The sensitivity of coverage area to both antenna beamwidth and height is compared. The analysis is extended to multiple UAVs and a new packing scheme is proposed for multiple UAVs coverage that offers several advantages compared to prior approaches.

Beef Up mmWave Dense Cellular Networks With D2D-Assisted Cooperative Edge Caching

Edge caching is emerging as the most promising solution to reduce the content retrieval delay and relieve the huge burden on the backhaul links in the ultra-dense networks by proactive caching popular contents in the small base station (SBS). However, constraint cache resource of individual SBSs significantly throttles the performance of edge caching. In this paper, we propose a device-to-device (D2D) assisted cooperative edge caching (DCEC) policy for millimeter (mmWave) dense networks, which cooperatively utilizes the cache resource of users and SBSs in proximity. In the proposed DCEC policy, a content can be cached in either users’ devices or SBSs according to the content popularity, and a user can retrieve the requested content from neighboring users via D2D links or the neighboring SBSs via cellular links to efficiently exploit the cache diversity. Unlike existing cooperative caching policies in the lower frequency bands that require complex interference management techniques to suppress interference, we take advantage of directional antenna in mmWave systems to ensure high transmission rate whereas mitigating interference footprint. Taking the practical directional antenna model and the network density into consideration, we derive closed-form expressions of the backhaul offloading performance and content retrieval delay based on the stochastic information of network topology. In addition, analytical results indicate that, with the increase of the network density, the content retrieval delay via D2D links increases significantly while that via cellular links increases slightly. Comprehensive simulations validate our theoretical analysis and demonstrate that the proposed policy can achieve higher performance in offloading the backhaul traffic and reducing the content retrieval delay compared with the state-of-the-art most popular caching policy.

Power Optimization Assisted Interference Management for D2D Communications in mmWave Networks

Aiming at the problem of aggravated interference caused by the increasing number of devices, a transmitting power optimization algorithm is proposed, which combines the device association and beamwidth selection. In the premise of guaranteeing, the authenticity of millimeter wave (mmWave) application scenario, an mmWave device-to-device (D2D) network model is introduced, which integrates the roll off feature of Gaussian directional antenna model and the reflectivity of two-ray channel model. Specifically, the device association performed through distributed framework, and the beamwidth scheme optimized by the particle swarm optimization (PSO) algorithm, solve the non-convexity problem of transmitting power optimization in mmWave D2D networks. Simulation results indicate that, compared with the existing interference management algorithms which ignore the transmitting power of devices, the proposed algorithm can effectively reduce the transmitting power and interference, and the superior performance can be achieved.

On Connectivity of Wireless Sensor Networks with Directional Antennas.

In this paper, we investigate the network connectivity of wireless sensor networks with directional antennas. In particular, we establish a general framework to analyze the network connectivity while considering various antenna models and the channel randomness. Since existing directional antenna models have their pros and cons in the accuracy of reflecting realistic antennas and the computational complexity, we propose a new analytical directional antenna model called the iris model to balance the accuracy against the complexity. We conduct extensive simulations to evaluate the analytical framework. Our results show that our proposed analytical model on the network connectivity is accurate, and our iris antenna model can provide a better approximation to realistic directional antennas than other existing antenna models.

Toward Robust Relay Placement in 60 GHz mmWave Wireless Personal Area Networks with Directional Antenna

Multimedia streaming applications with stringent QoS requirements in 60 GHz mmWave wireless personal area networks (WPANs) demand high rate and low latency data transfer as well as little service disruption. In this paper, we consider the problem of robust relay placement in 60 GHz WPANs with directional antenna. Relays forward traffic from transmitter devices to receiver devices facilitating i) the primary communication path for non-line-of-sight (NLOS) transceiver pairs, and ii) secondary (backup) communication path for line-of-sight (LOS) or NLOS transceiver pairs. By incorporating a classic directional antenna model and characterizing the link contention, we formulate the robust minimum relay placement problem and the robust maximum utility relay placement problem with the objective to minimize the number of relays deployed and maximize the network utility, respectively. Efficient algorithms are developed to solve both problems and have been shown to incur less service disruption in presence of moving subjects that may block the LOS paths in the environment.

Surface-Reflection-Based Communication and Localization in Underwater Sensor Networks

Most communication and localization algorithms in underwater environments have been constrained by dependencies on the Line Of Sight (LOS), which is hard to guarantee due to the inherent node mobility. This constraint hinders node discovery and ad hoc formation in underwater networks and limits the performance of routing protocols. This article introduces a novel Surface-Based Reflection (SBR) model that uses a homomorphic deconvolution technique to establish water-surface-reflected communication links. We then propose a Surface-Based Reflection Anchor-free Localization (SBR-AL) algorithm that can be employed by the individual nodes to establish a relative coordinate system. Our approach also employs a switch-beamed directional antenna model that allows each node to use the LOS estimated from SBR-AL to enable directional communication which is beneficial for higher Signal-to-Noise Ratios (SNR). The relative locations can facilitate the various network operation functions such as geo-routing and collision-free medium access. The simulation results confirm the effectiveness of the proposed approach.

On Capacity of Wireless Networks Using Practical Directional Antennas

Capacity is one fundamental problem in wireless Ad hoc networks. Deploying directional antennas to wireless networks can reduce interference among concurrent transmissions and increase spatial reuse, while the technology of multi-channel can separate concurrent transmissions. Therefore, combining these two technologies into one wireless network is capable of great improvement on the network capacity. Recent studies proposed a multi-channel network architecture that equips each wireless node with multiple directional antennas, which is called MC-MDA network. The capacity in MC-MDA network is derived under arbitrary and random placements. However, they only used a simplified directional antenna model. For approaching the more accurate capacity in real scenario, we consider a hybrid antenna model, which takes the effect of side lobe into account. We derive the capacity upper-bounds of MC-MDA networks in arbitrary and random network with the hybrid model to find the effect of side lobe. We show that the network capacity is closely related to the ratio of the radiuses of side lobe to main lobe. The capacity decreases when the ratio increases. Moreover, we compare the network capacity of MC-MDA using the simplified antenna model with our results.

STRONG CONNECTIVITY IN SENSOR NETWORKS WITH GIVEN NUMBER OF DIRECTIONAL ANTENNAE OF BOUNDED ANGLE

Traditional approaches to connectivity in sensor networks are based on the omnidirectional antenna model which relies on the assumption that the sensors send and receive in all directions. Current technologies make possible the utilization of sensors with directional antenna capabilities whereby the sensors send and/or receive along a sector of a predefined angle (or beam-width). Although several researchers in the scientific literature have investigated the impact of directional antennae on network throughput, energy consumption, as well as security very little is known concerning the effect of directional antennae on its connectivity. In this paper, we introduce for the first time a new sensor model with each sensor being able to transmit in any one of k directions, for some fixed k, and explore the algorithmic limits and potential of such a directional antenna model. More specifically, given a set of n sensors in the plane, we consider the problem of establishing a strongly connected ad hoc network from these sensors using directional antennae. In particular, we prove that given such set of sensors, each equipped with k, 1 ≤ k ≤ 5, directional antennae with any angle of transmission, these antennae can be oriented in such a way that the resulting communication structure is a strongly connected digraph spanning all n sensors. Moreover, the transmission range of the antennae is at most [Formula: see text] times the optimal range (a range necessary to establish a connected network on the same set of sensors using omnidirectional antennae). The algorithm which constructs this orientation runs in O(n) time provided a minimum spanning tree on the set of sensors is given. We show that our solution can be used to give a tradeoff on the range and angle when each sensor has one antenna. Further, we also prove that for two antennae it is NP-hard to decide whether such an orientation exists if both the transmission angle and range are small for each antennae.

Approximation algorithms for minimum latency data aggregation in wireless sensor networks with directional antenna

Real-time data aggregation is one of the most important issues in wireless sensor networks. Using directional antenna to transmit data can save energy and reduce interference. In this paper, we study the minimum latency data aggregation problem with the given two directional antenna models (the steering beam and the switch beam) under protocol interference model. We propose an approximation directional data aggregation algorithm to schedule data transmissions under two directional antenna models, respectively. At last, we evaluate the proposed schedule algorithms through simulations, and simulation results show that the proposed schedule’s latency is close to the depth of BFS tree, which is the lower bound of schedule latency, and the proposed schedules achieve extremely good performance.

Exact and performance‐guaranteed multicast algorithms for lifetime optimization in WANETs

AbstractWe consider the problem of maximizing the lifetime of a given multicast connection in wireless networks that use directional antennas and have limited energy resources. We provide a globally optimal solution to this problem by developing a general MILP formulation that can apply to many directional antenna models, some of which are not supported by the existing formulations. We also investigate the theoretical performance of a well‐known heuristic algorithm for this optimization problem in terms of its approximation ratio. We use a graph theoretic approach, for the first time, to derive an upper bound on its approximation ratio in an analytical expression and discover that it is a constant‐factor approximation algorithm. © 2009 Wiley Periodicals, Inc. NETWORKS, 2010

Simultaneous localization of multiple unknown CSMA-based wireless sensor network nodes using a mobile robot with a directional antenna

We use a single mobile robot equipped with a directional antenna to simultaneously localize unknown carrier sensing multiple access (CSMA)-based wireless sensor network nodes. We assume the robot can only sense radio transmissions at the physical layer. The robot does not know network configuration such as size and protocol. We formulate this new localization problem and propose a particle filter-based localization approach. We combine a CSMA model and a directional antenna model using multiple particle filters. The CSMA model provides network configuration data while the directional antenna model provides inputs for particle filters to update. Based on the particle distribution, we propose a robot motion planning algorithm that assists the robot to efficiently traverse the field to search radio source. The final localization scheme consists of two algorithms: a sensing algorithms that runs in O(n) time for n particles and a motion planning algorithm that runs in O(nl) time for l radio sources. We have implemented the algorithm, and the results show that the algorithms are capable of localizing unknown networked radio sources effectively and robustly.

Efficient Directional Network Backbone Construction in Mobile Ad Hoc Networks

In this paper, we consider the issue of constructing an energy-efficient virtual network backbone in mobile ad hoc networks (MANETs) for broadcasting applications using directional antennas. In directional antenna models, the transmission/reception range is divided into several sectors and one or more sectors can be switched on for transmission. Therefore, data forwarding can be restricted to certain directions (sectors), and both energy consumption and interference can be reduced. We develop the notation of directional network backbone using the directional antenna model, and form the problem of the directional connected dominating set (DCDS) which is an extreme case of the directional network backbone using an unlimited number of directional antennas. The minimum DCDS problem is proved to be NP-complete. A localized heuristic algorithm for constructing a small DCDS and two extensions of the algorithm are proposed. Performance analysis includes an analytical study in terms of an approximation ratio and a simulation study on the proposed algorithms using both a custom simulator and ns2.