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Flying Ad-hoc Networks (FANETs) company

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Flying Ad-hoc Networks (FANETs) comprise of a gathering of Unmanned Air Vehicle (UAVs) progressively shaping a transitory system without the utilization of any current foundation or concentrated organization. In this paper the impact of variation of different fading channel with variation of antenna of air vehicle over building is investigated. For this purpose Qualnet6.1 simulator has been used and this paper present the impact of flying nodes over the building by the performance of FANET by varying different antenna with speed of node by using Rayleigh fading has been evaluated. The performance has been compared in term of average delay, throughput, average jitter, & packet delivery ratio. The results are showing various changes due to change in antenna with variation of speed of nodes using Rayleigh fading over building of air vehicle.

FANETs (Flying Ad-hoc Networks) is a group of Unmanned Air Vehicle (Flying nodes) communicating with each other with no need to access point, but at least one of them must be connected to a ground base or satellite [1]. Flying nodes work without human help, like autopilot. This is because cheaper and small wireless communicating devices, the in recent years, many research fields from academia and industry make attention on FANETs. Now, FANETs are used in various applications such as military and civil applications [1], such as managing wildfire [2] and disaster monitoring [3]. As each type of network has its own specification and using the protocol depends on this specification, it is important to use a reliable protocol for this kind of networks and check their performance using simulation. Two factors affect protocol simulation: the first one is mobility model, and the second one is the communicating traffic pattern, among others. This paper focuses on the routing protocols and mobility models that have been used in the FANET network to solve communication, cooperation and collaboration problem between Flying nodes. FANET are a special case of mobile ad hoc networks (MANETs) [4]. FANET are a network with Flying nodes in the sky [1], which can automatically fly without human help. It consists of two parts, ad-hoc network and access point like a satellite or ground base to connect with the network in at least one of them, according to carry the data from one ground base to another. The network that its link is established between each Flying nodes and an access point is not specified as FANET network. Using multi- in the Flying nodes is network family reflects many advantages on this network.

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High Mobility

FANET node are exceedingly portable, with run of the mill UAV velocities of 30-460 km/hr [1] . Such profoundly portable UAVs can’t be served by regular techniques, for example, mobile Internet protocol (IP). Moreover, the efficiency of routing decisions and the quality of wireless links fluctuates due to the high speed of UAVs, leading to performance degradation . A media access control (MAC) layer tends to this issue by keeping up Quality of Service (QOS) for one jump transmission, though the steering layer guarantees solid end-to-end conveyance. One potential answer for experiencing the high versatility of UAVs needs to foresee the area and development of UAVs utilizing heuristic systems. On the great side, when FANETs are utilized as handing-off systems, the high portability factor gives wanted results in the foundation of deferral tolerant connections between topographically removed frameworks.

Fading

Fading in wireless means deviation of the attenuation of a signal with various variable which is affecting a signal over a particular propagation media. It may vary with frequency, position and time. Factors affecting are multipath propagation and shadowing. Fast fading is due to multipath propagation of transmitted signal. Signal received may destructively and add constructively at the receiver side due to which power level can be different. If there is direct line of sight path between sender and receiver then it follows Rayleigh, Rician, fast Rayleigh fading channel discussed using qualnet 6.1

Rayleigh Fading

The Rayleigh fading model comes about, primarily, due to presence of multipath signals. By multipath we mean that the transmitted signal reaches the receiver via a number of different path (multiple path) due to reflections from obstacles in the signaling environment such as tree, people and building. Because these paths have different lengths, they have different phase upon reaching their destination. Therefore, destructively or constructively interfere causing strong or weaker signal at different receiver locations. When the signal strength is weak signals at different receiver locations. When the signal strength is weak, the signal is referred to be as faded. The well know Rayleigh fading model assumes no (dominant) direct path.

Antenna

In general, an antenna is a device that is used for radiating/collecting electromagnetic energy (radio signals) into/from space. For the simulation scenario omnidirectional and three types of directional antenna has been used which is given as:

  1. Omni directional antenna
  2. Steerable antenna
  3. Switched beam antenna
  4. Pattern antenna

Omni directional antenna

One hypothetical Omni-directional antenna, called isotropic, is a point in space that radiates power in all directions equally. This ideal antenna is often taken as a reference model of practical antennas. A half-wave dipole is a practical Omni-directional antenna, which has a circular radiation pattern in the azimuth plane or in the elevation plane. As an Omni-directional antenna radiates radio signals in all directions, only a small percentage of them can reach the desired nodes and most of them are scattered into space. The scattered radio signals can cause interference with nodes within the coverage of the antenna. Besides, Omni-directional antennas have low efficiency in the frequency reuse as a number of channels are required to avoid interference.

Steerable antenna

Steerable antenna is additionally a kind of directional antenna that is used to reduce the interference. In an exceedingly network, once the source nodes cannot focus to a selected angle of the receiver node, a steerable antenna has capability to try and do this. Steerable antenna consists of every type of antenna elements in such a way that the beam is directed towards the receiver node at a selected angle. The antenna elements are placed in such a way that main lobe, side lobe and tail lobe do not create interference and thus interference is reduced.

Switched beam antenna

The antenna beam patterns are predetermined by shifting every antenna element’s signal phase. Weights for antenna elements, which are used to produce the desired beam pattern, can be locally saved in memory and instantaneously switched.

Pattern Antenna

Pattern antennas point RF energy in a specific direction for RF concentration within a targeted area. The gain is higher for that area or in that direction. The high gain pattern antenna are good for sites requiring a directed coverage in specific area or wireless back haul extensions where two wireless access points are connected with each other to extend the wireless network, rather than connected them to wired backbone.

Effect on Buildings

The vibration of buildings due to aircraft noise and the associated potential for structural damage and evidenced by the frequency with which building vibration complaints have appeared. The effect of tall building as the Tall buildings can cause radar interference and can prevent aircraft being detected or can cause false aircraft positions to be displayed to a controllers. Modern radar have built-in processing systems to counter these interference effects. Buildings can interfere with outbound pulses, returning pulses or both they can weaken radio signals and reflect them. Signal weakening can prevent radar detecting aircraft, and reflections can cause genuine aircraft to be detected in the wrong place. Usually, when this occurs, the radar detects the aircraft in the correct place at the same time Normally, the most sensitive parts of a structure to airborne noise are the windows. Though infrequent, plastered walls and ceilings can also be sensitive Peak sound pressures are normally assessed to determine the possibility of damage to a structure. In general, when peak sound levels are above 130 dB, structural parts are affected. Certain frequencies may cause more concern than others. For example, window breakage can occur at 30 hertz. However, only sounds lasting more than one second above 130 dB are potentially damaging to structural parts. The potential for increased weakness of structural components of historical buildings and sites is of concern. Aircraft noise may affect such sites more severely than newer, modern structures. Particularly in older structures, surface cracks may be initiated by vibrations from aircraft noise.

QOS Parameter

The following QOS parameters are used for analyzing the performance of the network These parameters are described below:

Throughput

Throughput is the average rate of all the successful data packet received by the destination from source. This is measured in bits/sec Throughput = Total packet received/Total packet send

Average End to End Delay

The difference in the calculation while transmitting , packets send time and received time is average end to end delay. Buffering during route discovery latency, retransmission delay. This is calculated by the formula D = (TR-TS)

Average Jitter

Jitter is the variation of the packet arrival time jitter is simply the difference in packet delay .In other words, jitter is used to measure time difference in packet inter arrival.

Packet Delivery Ratio

Packet delivery ratio is defined as the ratio of data packet by the destination to those generated by the source.

Simulation Setup and Environment

The simulation model was developed in the scalable and portable simulator qualnet 6.1 with the feature supporting different data rate and different speed of flying nodes. For the simulation setup 50 mobile nodes are randomly placed in terrain size of 1500mx1500m .The access point is put at the centre. The mobility model and the energy model used are random waypoint. The battery model and propagation model used is linear and Jitter, Packet delivery ratio End to End delay, Throughput. For the traffic generation, the traffic source used is CBR (constant bit rate) in which 512 bytes of data at data rate of 2mbps rate is sent over the network. There are 5 CBR connection are done. The design scenario of 50 nodes randomly placed in the defined terrain.

Simulation Results

In this paper three scenarios are simulated. In the first scenario, all 50 flying nodes are equipped over building. In the second scenario, different antenna are varied. In the third scenario, speed of nodes are varied by using of Rayleigh fading environment. The main purpose of the above simulation is to compare various QOS parameters like average Throughput, average end to end delay, average jitter, packet delivery ratio in FANET for Rayleigh fading with different antenna and variation of speed of nodes over building.

As the speed of air vehicle node increases the end to end delay for patterned antenna and omnidirectional antenna increases for as increases the high speed of nodes but for the switched antenna and steerable antenna end to end delay is minimum the end to end delay steerable antenna and switched antenna is better than the other antenna.

As the speed of flying nodes increases jitter for omnidirectional antenna increases but the steerable antenna has better jitter. As the speed of flying nodes increases throughput for different antennas decreases but steerable antenna has better throughput than other antenna. As the speed of flying air vehicle increases packet delivery ratio for steerable antenna is better than from other antenna. As speed increases packet delivery ratio for FANET decreases for different antenna.

From the above results, it can be seen that in FANET, the steerable antenna produces higher throughput than other antenna’s. In the speed varying environment, for getting the higher throughput only steerable beam antenna should be used. And in case of Average End to End delay and jitter the delay and jitter is high in case of omnidirectional, antenna and patterned antenna as compared to the steerable antenna and switched antenna. Directional antenna like steerable and switched beam antenna are more efficient in sending packets correctly at the destination.

So from the above results, it can be conclude that in varying speed environment, by using steerable antennas the Quality of Service (QOS) parameters can be improved and enhanced but there is always some limitation and challenges in the MAC layer and Physical layer which affect the performance of the antennas.

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