Improvement of QoS Parameters by using Directional Antennas in MANET

Sumit Suhag* Ashu Gupta Manoj Duhan M.Tech Scholar, ECE M.Tech Scholar, ECE, Professor, Deptt.of ECE DCRUST Murthal, Haryana DCRUST Murthal, Haryana DCRUST Murthal, Haryana Ssehwag11@gmail.com guptaashu1710@gmail.com duhan_manoj@rediffmail.com

Abstract—In Wireless mobile ad hoc networks (MANET) complexities have been increasing day by day because of increasing number of nodes and their highly random or dynamic behaviour. At every point of time the topology of the various nodes in MANET is changing, hence the system complexity also increases. So this is the priority that as the system topology changes we have to implement certain technology pertaining to the stability and an optimum efficiency of the network. For the improvement in the network congestion we have introduced directional antennas. Also this paper compares and analyse different antennas such as omni directional, steerable and switched beam antennas in different scenarios for Reactive routing protocols (AODV) used in MANET. It also includes analysis of various QoS (Quality of Service) parameters like Average Throughput, Average End-to-End Delay, Average Jitter, and Packet Delivery Ratio that determines the quality of network and its performance. We are using 50 nodes in rectangular frames with Random Waypoint mobility model and the simulation is carried out in the GUI based Simulator QualNet 7.1.

Keywords— MANET, omni directional antenna, directional antennas, QoS, Reactive routing protocols, AODV

I. INTRODUCTIONWireless mobile Ad hoc networks (MANET) [1] are playing an important role in day to day communication and

mainly used by community users like emergency services, military applications, business, researchers and students services. MANET is a network that can be deployed at anytime and at anywhere because of its minimum requirement for administration and easy to setup the infrastructure.

Typically, Wireless MANET [2] consists of mobile nodes that are equipped with omni directional antennas. An omni directional antenna broadcast radio signals in all the directions but only the small part of radio signals can reach to the destination node. The major part of the radio signals gets scattered into free space. And within the antenna coverage range the unused scattered signals cause interference to the neighbouring nodes that affect the network performance [3]. Due to high interference in the network equipped with omni directional antenna leads to limited capacity and low spatial reuse [4].

But in case of directional antennas, the radio signals will not get scattered in all directions but to a particular direction because these antennas concentrates their transmission and reception in a certain direction. This will cause less interference to the other neighbouring nodes and the ongoing transmission.

II. DIRECTIONAL ANTENNASInitially the directional antennas [5] used to be non feasible because of its cost and size but with the continuing

reductions in the size and cost of directional antenna in recent years, it has become feasible to use directional antennas for wireless mobile ad hoc networks. The antennas that spreads all its radio signals into all the directions is known as omni directional antennas whereas, the antennas that spreads all their radio signals into a particular defined direction are termed as directional antennas. There are various directional antennas that are being practically implemented like steerable antennas, switched beam antennas and patterned antennas. Directional antennas work more efficiently than omni directional antennas and produce better results. There are various benefits or advantages [6] of using directional antennas over omni directional antennas which are listed below:

A. Benefits of directional antennasThe directional antennas are much more efficient than the omni directional antennas because of the various benefits like:1) Longer transmission range: Due to the high directivity of these antennas, they will focus their energy in one

particular direction that results in longer range of transmission.2) High gain: As the data or the radio signals scattered in one direction, most of the signals will easily reach to the

desired destination that results in high gain.3) Less power requirement: Power requirement of the directional antennas is less than the omni directional antennas

because the directional antenna transmits the radio signals in only one direction.4) High spatial reuse: Due to the directional antennas the more number of simultaneous transmissions can be

carried out in the network, so the spatial reuse is improved by the use of directional antennas.

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5) Low interference: As the directional antennas concentrate the radio signals to one particular direction so, the radio signals will not interfere with other signals of the neighbouring nodes. This results in lower interference in the network system.

6) Shorter end-to-end delay: The directional antennas have higher transmission range that means there are less number of hops due to less hop count overall end-to-end delay of the system reduces.

Overall, there are numerous advantages of using directional antennas over omni directional antennas in which some of them are mentioned above. Only the physical layer limitations restrict the applications of antennas so, many researches are going on to improve the physical layer to improve the applications of these antennas [7].

III. ROUTING PROTOCOLSRouting plays an important role in forwarding packets of data from source node to the destination node. If the packets

are not reaching to the destination it means that there is not an efficient path or route between the source node and destination node. Also we can say that there is not an efficient routing mechanism between source and destination. Therefore, for carrying out an efficient mode of communication so that no packet loss or drop happens we must adopt a good and efficient routing mechanism between source node and the destination nodes. There are different kinds of routing protocols like: Reactive, Proactive and Hybrid routing protocols [2], [8].

Qualitatively, out of the above said routing protocols, Reactive protocols are widely used and preferred over other routing protocols because there is no need to maintain the tabular data of several routes between the source node and the destination node. In Reactive routing protocols, the route identification is done by sending route request packet (RREQ) to the corresponding or neighbouring nodes then again these nodes spreads the message to next neighbouring nodes. The reply packet (RREP) is forwarded to the source following the same path as that of RREQ packet [9]. The message is broadcast to the neighbouring nodes till it reaches its destination. Here in this paper, we rely on the qualitatively best Reactive protocols i.e. Ad-Hoc On-Demand Distance Vector (AODV).

AODV [10] is the demand driven reactive routing protocol that includes the on demand routing mechanism of route discovery and route maintenance. In this, updating of packets and multiple hops sequencing number is done periodically. When there is the request of route and if the route is not available, a route request (RREQ) message is generated and broadcasted in a limited way to its neighbours. The traffic is controlled by the help of some Initial delay which is due to delay in transmitting the packet to the selected nodes. Once the RREQ is reached to its destination node, which has the path up to the route in its cache, the route is found [11]. And if the connection is established, the message is sent to its destination. AODV is very scalable to the large networks and also highly adaptive to the dynamic networks [12].

IV. SIMULATION SETUP AND ENVIRONMENTThe simulation model was developed in the scalable and portable simulator QualNet 7.1 [13] with the features

supporting various directional antennas. For the simulation setup, we took 50 mobile nodes randomly placed in a terrain size of 1500 x 1500 m² (Fig. 1). The mobility model [14] and energy model used are Random Waypoint model and MicaZ respectively. The battery model and propagation model used is linear model and Two Ray model respectively. For the traffic generation, the traffic source used is CBR (Constant Bit Rate) in which 512 bytes of data at 2Mbps rate is sent over the network. Moreover total number of packets sent are 24 and total number of bytes sent are 12288. The design scenario of 50 nodes randomly placed in the defined terrain is shown below in Fig. 1.

Fig. 1 Design scenario of 50 nodes placed randomly

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There are different default values and user defined values are taken in carrying out the simulations The simulation parameters and the antenna parameters are summarized below in Table I and Table II respectively.

TABLE ISIMULATION PARAMETERS

Parameters ValuesSimulator QualNet simulator 7.1Terrain size 1500 x 1500 m²No. Of nodes 50Radio type 802.11bMAC Protocol 802.11Network Protocol IPv4Data Size 512 BytesData Rate 2MbpsMobility Model Random Way PointPropagation Model Two Ray GroundChannel Frequency 2.4 GHzTraffic Source CBRNode Speed Min. =1 m/s, Max. = 10 m/sSimulation time 120 SecBattery Model Type Mica ZRouting Protocol AODVRouting Type Generic

TABLE IIIANTENNA PARAMETERS

Parameters ValuesAntenna Model Omni directional, Steerable,

Switched BeamAntenna Gain 1.0 dbAntenna Height 1.5 mAntenna Efficiency 0.8Antenna Mismatch loss 0.3 dbAntenna Connection loss 0.2 dbAntenna Cable loss 0.01 dbNoise Factor 10.0Temperature 290.0 K

The run time simulation scenario of 50 nodes placed in 1500 x 1500 m2 terrain equipped with omni directional antennas is shown in Fig. 2. The routing protocols used for the simulations are proactive, reactive and hybrid protocols [10]. The proactive protocols used in simulation are AODV, DYMO. The reactive protocol used in simulations is FISHEYE and the hybrid protocol used in the simulation is ZRP.

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Fig. 2 Run time simulation scenario for 50 nodes equipped with omni directional antennas. The run time simulation scenario for 50 nodes equipped with steerable antennas and switched beam antennas are shown below in Fig. 3 and Fig. 4 respectively.

sFig. 3 Run time simulation scenario for 50 nodes equipped with steerable directional antennas.

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Fig. 4 Run time simulation scenario for 50 nodes equipped with switched beam directional antennas. V. SIMULATION RESULTS

In this paper three scenarios were simulated. In the first scenario, all 50 nodes were equipped with omni-directional antennas and reactive routing protocols (AODV) was used. In the second scenario, all the 50 nodes were equipped with steerable directional antennas and AODV routing protocols was used. In the third scenario, all the 50 nodes were equipped with switched beam directional antennas and the AODV reactive routing protocols was used.

The main purpose of the above simulation was to compare various QoS parameters like Average Throughput, Average End-to End Delay, Average Jitter, Packet Delivery Ratio in wireless MANET for omni directional and both the above mentioned directional antennas. The overall simulation result is shown in Table III.

TABLE IIIIISIMULATION RESULTS

QoS Parameters Antenna Model UsedOmni directional Steerable Antenna Switched Beam

AntennaAverage Throughput (bits/sec)

4104.26 4295.38 4296.86

Average End-to-End Delay (sec)

0.019422 0.015345 0.015714

Average Jitter (seconds) 0.009095 0.005257 0.005649Packet Delivery Ratio (%) 91.67 100 100

According to the above simulation results, comparisons of the various QoS parameters were carried out between omni directional antennas and directional antennas like steerable and switched beam antennas. The comparison is done by the help of bar graphs shown below.

Fig. 5 shows the comparison of the average value of throughput for MANET using the said omni and directional antennas. From the results we find that the highest average value of throughput is achieved in case of steerable and switched beam directional antennas whereas in case of omni directional antennas the value of throughput is comparatively very less.

Omni directional Steerable Antenna Switched Beam4000

4050

4100

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4350

Average Throughput (bits/sec)

Ave

rage

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ough

put (

bits

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Fig. 5 Comparison of Average Throughput between omni directional, steerable and switched beam antennas.

In the Fig. 6 we can see the comparison of the value of average end-to-end delay among omni directional, steerable and switched beam antennas. From the results, we noted that the smallest value of average end-to-end delay is achieved only in case of directional antennas (steerable) as compared with the omni directional antennas.

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Omni directional Steerable Antenna Switched Beam0

0.005

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0.015

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Average End-to-End Delay (sec)

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elay

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Fig. 6 Comparison of Average end-to-end delay between omni directional, steerable and switched beam antennas

Fig. 7 contains the comparison of the values of average jitter between omni directional and two directional antennas. The lowest value of average jitter was achieved in case of directional antennas (steerable) as compared with the omni directional antenna.

Omni directional Steerable Antenna Switched Beam0

0.001

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Average Jitter (seconds)

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rage

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ec)

Fig. 7 Comparison of Average Jitter between omni directional, steerable and switched beam antennas

In the Fig. 8 the packet delivery ratio parameter is compared using omni directional, steerable and switched beam antennas. We noticed that for steerable and switched beam antennas the packet delivery ratio is 100% whereas the omni directional antenna produced 91.67%. It means in case of directional antennas there is a mere chance of packet drop or lost whereas the chances of packet drop or lost is more in case of omni directional antenna.

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Omni directional Steerable Antenna Switched Beam86

88

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Packet Delivery Ratio (%)

Pack

et D

eliv

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io (%

)

Fig. 8 Comparison of Packet delivery ratio between omni directional, steerable and switched beam antennas

VI. CONCLUSIONS Here the three simulations were carried out using omni directional, steerable and switched beam antennas to compare the various parameters deciding the quality of the network. The QoS parameters like Average Throughput, Average End-to-End Delay, Average Jitter, and Packet Delivery Ratio were chosen to check the performance and efficiency of the network in different scenarios. In first simulation scenario omni directional antenna was used for all nodes in the network whereas, for the second and third simulation scenario steerable and switched beam directional antennas were used for all the nodes in the network respectively. From the above results, the various conclusions can be drawn that in case of Average Throughput, both the directional antennas produce high throughput than the omni directional. In case of Average End-to-End Delay and Average Jitter, the delay and Jitter is high in case of omni directional antenna as compared with steerable antenna and switched beam antennas. Directional antennas like steerable and switched beam are more efficient in sending packets correctly at the destination because from the above results the Packet Delivery Ratio is 100% in case of directional antennas whereas only 91.67% in case of omni directional antenna. So from the above results, we can conclude that by using directional antennas the Quality of Service (QoS) parameters can be improved and enhanced but there is always some limitation and challenges in the MAC and physical layer which affect the performance of the directional antennas.

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[10] Charles Perkins and Elizabeth Royer, “Ad Hoc On-Demand Distance Vector Routing,” Proc. of the 2nd IEEE Workshop on Mobile Computing Systems and Applications, pages 90–100, 1999.[11] Akkaphop Otakahn, Mayuree Lertwatechakul, “An Improvement of Ad Hoc Route Maintenance”, Department of Information Engineering, Faculty of Engineering, King Mongkut's Institute of Technology, Ladkrabang[12] Harminder Qian Feng, Zhongmin Cai, Jin Yang, Xunchao Hu, “A Performance Comparison of Ad Hoc Network Protocols”, Second International Workshop on Computer Science and Engineering, 2009 IEEE.[13] The Network Simulator QualNet 7.1, [Online], Available: http://www.scalable-network.com/products/qualnet/..[14] Tracy Camp, Jeff Boleng, Vanessa Davies “A Survey of Mobility Models for Ad Hoc Network Research”, Wireless

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