Beamwidth Of Directional Antenna Research Articles

Performance Analysis of Millimeter-Wave Relaying: Impacts of Beamwidth and Self-Interference

We study the maximum achievable rate of a two-hop amplified-and-forward (AF) relaying millimeter-wave (mm-wave) system, where two AF relaying schemes, i.e., half-duplex (HD) and full-duplex (FD) are discussed. By considering the two-ray mm-wave channel and the Gaussian-type directional antenna, jointly, the impacts of the beamwidth and the self-interference coefficient on maximum achievable rates are investigated. Results show that, under a sum-power constraint, the rate of FD-AF mm-wave relaying outperforms its HD counterpart only when antennas with narrower beamwidth and smaller self-interference coefficient are applied. However, when the sum-power budget is sufficiently high or the beamwidth of directional antenna is sufficiently small, direct transmission becomes the best strategy, rather than the AF relaying schemes. For both relaying schemes, we show that the rates of both AF relaying schemes scale as O(min{θ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , θ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> }) with respect to beamwidth θ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> , and the rate of FD-AF relaying scales as O(μ <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-(1/2)</sup> ) with respect to self-interference coefficient μ. Also, we show that ground reflections may significantly affect the performance of mm-wave communications, constructively or destructively. Thus, the impact of ground reflections deserves careful considerations for analyzing or designing future mm-wave wireless networks.

AREP: An asymmetric link-based reverse routing protocol for underwater acoustic sensor networks

Routing protocol design is one of the fundamental requirements of Underwater Acoustic Sensor Networks (UASNs). However, traditional underwater routing protocols focus on the particularities of underwater environment, while ignoring the features of underwater nodes that influence route establishment. In this study, the impact of the directional beam width of underwater nodes on communication links was fully explored. The presented case studies indicate that for fixed beam width of directional antennas, the relative position change of two geographically adjacent nodes is prone to generate asymmetric links. To ensure bidirectional data communication between source nodes and destination nodes, an asymmetric link-based reverse routing (AREP) is proposed. In AREP, each node maintains a neighbor table in which items are used to analyze the link state. Routing paths are established by prioritizing the utilization of symmetric links. When an asymmetric link is required to be introduced into a routing path, a three-hop-constrained circuitous route will be established for ease of reverse routing search. The routing void problem is addressed in AREP through eliminating void nodes. A routing update is periodically conducted to dynamically adjust previous routing paths to the change of network topology caused by node mobility. Simulation results demonstrated that AREP improves network performance in terms of transmission delay, packet delivery ratio, as well as energy consumption.

Multicast Capacity for VANETs With Directional Antenna and Delay Constraint Under Random Walk Mobility Model

In this paper, we investigate the multicast capacity for vehicular ad hoc networks with directional antennas and the end-to-end delay constraint. We consider a torus of unit area with $n$ vehicles (nodes), there are $n_{s}$ multicast sessions and each session contains one source vehicle which is associated with $p$ destinations. We study the 2D and 1D random walk mobility models with two different time scales, i.e., fast and slow mobility. Given a delay constraint $D$ and assuming that each vehicle is equipped with a directional antenna, we obtain the multicast capacity of the two mobility models with two different time scales in the order of magnitude, respectively. We then characterize the impact of the network parameters (i.e., the end-to-end delay constraint $D$ , the beamwidth of directional antenna $\theta$ , and the number of destinations $p$ in each session) on the multicast capacity. Moreover, we find that the unicast capacity can be considered as a special case of our multicast results when the beamwidth of directional antenna $\theta$ tends to $2\pi$ and the number of destinations $p$ tends to 1 in the sense of probability.

Capacity analysis of inhomogeneous hybrid wireless networks using directional antennas

Most of studies on network capacity are based on the assumption that all the nodes are uniformly distributed, which means that the networks are characterized by homogeneity. However, many realistic networks exhibit inhomogeneity due to natural and man-made reasons. In this work, the capacity of inhomogeneous hybrid networks with directional antennas for the first time is studied. By setting different node distribution probabilities, the whole network can be devided into dense cells and sparse cells. On this basis, an inhomogeneous hybrid network model is proposed. The network can exhibit significant inhomogeneity due to the coexistence of two types of cells. Then, we derive the network capacity and maximize the capacity under different channel allocation schemes. Finally, how the network parameters influence the network capacity is analyzed. It is found that if there are plenty of base stations, the per-node throughput can achieve constant order, and if the beamwidth of directional antenna is small enough, the network capacity can scale.

Improving Capacity and Delay in Directional Hybrid Wireless Networks with Range Extension

With the introduction of directional antennas into wireless networks, the beamwidth decreases and the range extends; thus both the mutual interference and the number of hops are reduced. This paper investigates the asymptotic throughput capacity and delay of hybrid wireless networks equipped with directional antennas. We first present a new scheme combining directional antennas and the same cell routing policy, and then derive the per-node throughput capacity and average delay in the proposed scheme, which mainly depend on the number of base stations m, the beamwidth of directional antennas θ, and the path loss exponent α. The discussions that how our directional hybrid wireless network explores the transmission range extension of directional antennas and how each parameter influences the throughput and delay are further elaborated. Moreover, our analytic results and experiments demonstrate that the substantial improvements on throughput capacity and the obvious reduction of average delay are achieved in hybrid wireless networks with directional antennas.

Multicast Capacity for VANETs with Directional Antenna and Delay Constraint

Vehicular Ad Hoc Networks (VANETs) with base stations are called hybrid VANET, where base stations are deployed to improve the throughput capacity. In this paper, we study the multicast throughput capacity for hybrid wireless VANET with a directional antenna on each vehicle and the end-to-end delay is constrained. In the hybrid VANET, there are n mobile vehicles (or nodes) distributed in a unit area with m strategically deployed base stations connected using high-bandwidth wire links. There are n_s multicast sessions and each multicast session has one source which transmits identical data to its associated p destinations. We investigate the multicast throughput capacity for two mobility models with two mobility scales, respectively, while each vehicular node is equipped with a directional antenna and with a tolerant delay D. That is, a source node transmits to its p destinations only with the help of normal nodes within D consecutive time slots. Otherwise, the transmission will be performed with in the infrastructure mode, i.e., with the help of base stations. We demonstrate that the one dimensional i.i.d. slow mobility pattern catch the main feature of VANETs. And we find that the multicast throughput capacity of the hybrid wireless VANET greatly depends on the delay constraint D, the number of base stations m, and the beamwidth of directional antenna θ. In the order of magnitude, we obtain the closed form of the multicast throughput capacity of the hybrid directional VANET, where the impact of D, m and θ on the multicast throughput capacity is analyzed. Moreover, we derive the lower bound of the muticast throughput using a similar raptor coding approach.

Capacity of Hybrid Wireless Networks with Directional Antenna and Delay Constraint

We study the throughput capacity of hybrid wireless networks with a directional antenna. The hybrid wireless network consists of n randomly distributed nodes equipped with a directional antenna, and m regularly placed base stations connected by optical links. We investigate the ad hoc mode throughput capacity when each node is equipped with a directional antenna under an L-maximum-hop resource allocation. That is, a source node transmits to its destination only with the help of normal nodes within L hops. Otherwise, the transmission will be carried out in the infrastructure mode, i.e., with the help of base stations. We find that the throughput capacity of a hybrid wireless network greatly depends on the maximum hop L, the number of base stations m, and the beamwidth of directional antenna \theta. Assuming the total bandwidth W bits/sec of the network is split into three parts, i.e., W_1 for ad hoc mode, W_2 for uplink in the infrastructure mode, and W_3 for downlink in the infrastructure mode. We show that the throughput capacity of the hybrid directional wireless network is \Theta(\frac{nW_1}{\theta^2L\log n})+\Theta(mW_2), if L=\Omega(\frac{n^{1/3}}{\theta^{4/3}\log^{2/3} n}); and \Theta((\theta^2L^2\log n)W_1)+\Theta(m W_2), if L=o(\frac{n^{1/3}}{\theta^{4/3}\log^{2/3} n}), respectively. Finally, we analyze the impact of L, m and \theta on the throughput capacity of the hybrid networks.

On the gain and beamwidth of directional antennas

A formula is given for the maximum gain of a class of antennas having fields expressible as a finite number of spherical wave functions. This maximum gain can be achieved for arbitrarily polarized radiation fields, and it can be related to antenna size by requiring the near fields to be small in magnitude. Also, the radiation field is in the form of a polynomial, so that patterns optimum in the Tchebycheff sense can be defined. Formulas for the relationship of beamwidth to sidelobe level are given.