Performance Evaluation of Routing Protocols for ... - IEEE Xplore

2014 International Conference on Signal Processing and Integrated Networks (SPIN)

Performance Evaluation of Routing Protocols for sending Healthcare data over WiMAX network Basant Kumar Dept. of Electronics and Communication Engineering, Motilal Nehru National Institute of Technology Allahabad, Allahabad - 211004 (U.P.) , INDIA [email protected]

Shashwat Pathak Dept. of Electronics and Communication Engineering, Motilal Nehru National Institute of Technology Allahabad, Allahabad - 211004 (U.P.) , INDIA [email protected]

situations [5], where a mobile medical unit is crucial for the addressing trauma, monitoring and care of patient [6].Typical medical data types can be divided into two categories: Physiological data (ECG, Blood Pressure etc.) and Morphological data (X-Ray, CT Scan , Color Doppler etc.). Apart from this we can have Hospital Information system data, patient record information and tele-consultation video data. Data traffic of healthcare applications is random and demand based. It may be due to arrival of emergency or traffic from remote monitoring sources which send data as per onset of emergency or otherwise use network resources when it is almost free for patient record maintenance. These data types are affected by metrics such as end to end delay which ranges from 1s for physiological data and in range of 100 ms-400 ms for audio and video traffic respectively, is required and other factors such as packet delivery ratio and throughput for an informative reproduction of medical data over a network. Thus routing becomes an important task as it is associated with delivering information packets over network. The routes may be predefined as in case of proactive routing or based determined on onset of demand. In later case routing table stores only the best possible routes while link-state or topological databases may store all other information as well [6][7][8]. Hybrid routing harnesses the features of both and optimizes the performance of network in terms of mentioned metrics making it more faster by reducing end to end delay and increasing packet delivery ratio which overall affects the quality of service (QoS) of a given network for specific emergency situations. In Mobile WiMAX network, fixed Base Station (BS) is connected to public network with mobile subscriber stations (SS). It covers multiple sectors simultaneously. A variety of wireless routing protocols are already designed to facilitate and enhance communication in wireless environment, such as AODV, OLSR, DestinationSequenced Distance-Vector Routing (DSDV), ZRP, LAR, Landmark Ad Hoc Routing (LANMAR), Source Tree Adaptive Routing Protocol (STAR), Dynamic MANET Ondemand (DYMO).A study and comparison on network performance of AODV, DSR, DSDV routing protocols are evaluated and presented [9]. In this paper comparison is done among AODV, LAR1,OLSR and ZRP routing protocols for a medical scenario involving a moving ambulance and a

Abstract— In this paper, performance of different varieties of routing protocols is evaluated for Worldwide Interoperability for Microwave Access (WiMAX) [1] as part of feasibility study for its use in wireless telemedicine applications. Emergency telemedicine scenario of moving ambulance and mobile pedestrian, transmitting physiological patient data sending to hospital have been considered in present study. Due to mobility of entities involved, network topology changes frequently and routing becomes a challenging task. A variety of routing protocols with varying network conditions are analyzed to find an optimized protocol for sending critical healthcare data. This paper presents performance comparison of four popular WiMAX routing protocols i.e. Ad hoc On-Demand Distance Vector Routing (AODV), Location Aided Routing scheme1 (LAR1), Optimized Link State Routing Protocol (OLSR) and Zone Routing Protocol (ZRP) in variable number of nodes as well as variable pause time conditions. The performance analysis is based on different network metrics such as average jitter, packet delivery ratio, average end-to-end delay and throughput. Keywords— WiMAX, Telemedicine, m-Health, AODV, LAR1, OLSR and ZRP .

I.

INTRODUCTION

“Telemedicine is the use of medical information exchanged from one site to another via electronic communications to improve patients' health status” [2].In the first instance medical healthcare data was sent from distance in the early 20th century, when successful transmission of 100 electrocardiograms (ECGs) over a distance of 1.5 km took place [3].As the need for flexibility in usage, mobility support, deployment issues and increasing the reach of remote healthcare assistance use of wireless communications technology for medical service delivery is a necessity [4]. Advances in the field of wireless communication standards, paved the way for cost effective healthcare with added mobility to facilitate patient cases that could not be efficiently served earlier with the traditional fixed wired communication systems. Nowadays, the development in satellite systems, cellular technologies (different generations), , wireless local area networks (WLAN), emerging wireless mesh networks (WMN), mobile ad hoc networks (MANET) , Wireless Sensor Network (WSN) and Worldwide Interoperability for Microwave Access (WiMAX) can deliver medical assistance to critical emergency

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A. AODV AODV [10,11] is a distance vector routing for mobile ad-hoc networks. Route discovery is initiated on demand which eliminates the need for periodic update of routing table.

pedestrian sending physiological data to the hospital. Rest of the paper is organized as follows: Section II gives an overview of WiMAX standard and its applicability in healthcare system. Various routing protocols and their potential applications in telemedicine is discussed in Section III. Section IV describes the telemedicine scenario along with simulation parameters. Followed by Section V which contains performance comparison of routing protocols for the telemedicine scenario. Section VI concludes the presented study. II.

TABLE.I. DATA RATE REQUIREMENTS FOR DIFFERENT DEVICES USED IN HEALTHCARE MONITORING Data Rates

Devices

WORLDWIDE INTEROPERABILITY FOR MICROWAVE ACCESS(WIMAX)

The IEEE Standard 802.16-2001 [1] defines the Wireless MAN air interface specification for wireless metropolitan area networks (MANs). This standard serves as link between end stations and core telecommunication network through wireless broadband access. Its physical layer specifications depend upon the available frequency range with a set of air interfaces based on a common MAC protocol. The spectrum range is from 10 to 66 GHz, as approved in 2001. This standard integrates various layers and sub layers namely service-specific convergence sub layer (CS), the MAC common part sub layer (CPS), the security sub layer, and the physical layer. In entire span of a super frame interval all operations between BS and SS follow the procedures as defined by 802.16 standard. Implemented MAC management messages are used to operate the WiMAX network. IEEE 802.16 MAC protocol [7], [8] was designed for point-to-multipoint broadband wireless applications for achieving high data rates in both uplink and downlink . For serving the purpose of channel sharing among users resource allocation algorithms are used. The 802.16 MAC layer supports both kinds of traffic viz., continuous and burst, hence it offers immense scope for telemedicine traffic. WiMAX technology is advantageous especially for broadband wireless scenarios because of high bandwidth, QoS support , integrated services, and security. Trauma category includes transmission of multi parametric data such as blood pressure reading, heart rate ,region of interest (ROI) of an image, ultrasound video streaming as well as medical image and voice conference etc. The QoS variables depend on specific application. These are different for different layers with proper threshold for specific applications for guaranteed refaithfull reproduction at receiver end. For example it may be defined in terms of bit error rate, average jitter, latency, PSNR and throughput etc. Thus, a BS can fulfill these QoS requirements through proper resource allocation mechanism. Resource allocation in WiMAX is user specific. It depends upon equipment suppliers who have their own mechanisms and relevant algorithms to adapt from them. Their decisions are based on different efficient and environment adaptable scheduling schemes [9]. Mobile health (m-Health) [10] data rate requirements are listed in Table 1 [9].

Good

Excellent

ECG

2 kbps

12 kbps

Doppler Instrument

40 kbps

160 kbps

Blood Pressure Monitor

1 kbps

1 kbps

Ultrasound Machine

100 kbps

400 kbps

Camera

100 kbps

2,000 kbps

Stethoscope

40 kbps

160 kbps

Microphone

40 kbps

160 kbps

This dynamic link allocation mechanism introduces low processing and memory overhead, low network utilization, and determines unicast routes to destinations within the ad hoc network. Peculiar feature of this routing protocol is that if a route entry is not used within a stipulated time it will be removed. In this way existence of each reverse route entry is time bound. Its advantage in routing an emergency telemedicine traffic is that a route determination procedure initiates only on demand. Thus, when a route is needed, some sort of global search procedure is employed. Network can be used for routing other emergency healthcare data in case request from one node is idle. B. LAR1 LAR [12] is a reactive on-demand source routing protocol which harnesses the location information gained from Global Positioning System (GPS). Advantage of LAR over Dynamic Source Routing (DSR) is that route request packet flooding in former is much optimized due to assisted location information. Based on this location information route request packet for destination is forwarded in specific request zones only, instead of flooding of this information for route discovery in the entire dimension of ad-hoc network. This ultimately reduces end to end delay and transmission of emergency traffic is done with ease and through optimal route. C. OLSR OLSR is a proactive link-state routing protocol, which disseminates link state information by discovering it with the help of ‘ hello’ and ‘topology control’ (TC) messages in entire mobile ad-hoc network. This topology information is used by individual nodes to compute next hop destinations for all nodes in the network keeping in mind shortest hop forwarding paths [13]. When a node broadcasts its message, the retransmission of that message by multi point relays (MPR) ensures that the message is received by each of its two messages only the MPR nodes will rebroadcast the message meantime other neighbors

III . WIRELESS ROUTING PROTOCOLS FOR TELEMEDICINE APPLICATION

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will process the message but does not rebroadcast it and hence use of MPR is minimized. To diffuse topology information in the network, nodes periodically exchange Topology Control (TC) messages, with their neighbor. In OLSR, every node broadcasts periodic HELLO messages that contain one-hop neighbor information. The advantage of this schemes is when demand for a route initiates, there is little delay until the route is determined. This is motivation behind using this protocol for emergency healthcare applications as it reduces delay.

Nodes transmitting medical information are connected to nearby wireless access points in every direction. A mobile ambulance is moving in the town according to traffic conditions depicted here by pause times. Simulation parameters are summarized in table 2. Constant Bit Rate (CBR) nodes are positioned between 9-14 and 27-21 node numbers, between them the exchange of data is taking place. Performance of different routing protocols is analyzed under two test conditions: i. Varying network size.(4, 10, 20 ,30 nodes). ii. Varying pause times with 40 nodes (10 s, 30s ,50s, 70s, 100s.

D. ZRP It is a hybrid variety of routing protocol [14]. ZRP divides the complete network into several zones and employs various routing protocols within and between those zones and the selection of these protocols depends upon their optimized applicability . Originating from each node there is a well defined zone centered at concerned node with the defined in terms of parameter ‘r’ describing radius of this zone in hops. In each such zone a proactive protocol Intra Zone Routing Protocol (IARP) is adopted to maintain the local topology; as it helps in eradicating the initial delays during route searching and link establishment phase. As need for a link in between zones arises Inter Zone Routing Protocol (IERP), a reactive protocol, is used. It is used for finding the path between the source and the destination. Hence reducing memory overhead in storing topology of entire network at each node . Border cast Resolution Protocol (BRP) is an efficient broadcast technique which controls the traffic between such zones, and therefore, reduces the number forwarding in route discovery of IERP. The most appealing feature of this protocol is its adaptive behavior, based on the current configuration of the network and the behavior of the users which is in accordance with the required dynamics of critical healthcare scenarios. IV.

Fig. 1. A moving ambulance scenario in a town.

V.

RESULTS AND DISCUSSION

EMERGENCY MEDICAL SCENARION AND SIMULATIONS

Here a scenario of a small town is presented and simulation study has been performed in an area of 1500*1500 sq. mt. the town has fixed wireless access points at four different locations at four corners. They are linked with suitable backbone network. TABLE I.

Fig. 2. Throughput for different number of nodes

In Fig.2 it can be seen that throughput is more using LAR1 and OLSR routing protocols with severe packet drop using ZRP.

SIMULATION PARAMETERS

Parameters Simulator

QualNet

Protocols studied

AODV, LAR1,OLSR & ZRP

Number of nodes Simulation time

4,10,20,30 nodes for varying network size and 40 fixed nodes for varying mobility 501s

Simulation area

1500 *1500

Node movement model

Random waypoint mobility

Traffic types

2 CBR sources( 9-14, 27-21 nodes)

Mobility of nodes

Min speed= 1m/s , Max speed =10 m/s

Rate of packet generation

2 packets/sec

Values

Fig. 3. End to End delay for different number of nodes

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AODV shows less End to End delay in fig.3. Performance of LAR1 and OLSR is not far inferior it is almost 200ms more.

Fig. 7. Throughput for different pause times

Fig.7 shows that LAR1 and OLSR give maximum throughput in this case. With decrease in mobility the performance is in accordance with results of first experiment. Severe packet drops are reported using ZRP.

Fig. 4. Average Jitter for different number of nodes

Fig.4 suggests that Jitter values are higher for LAR1 and OLSR, as the node density is increasing OLSR is showing more jitter.

Fig. 8. End to End Delay for different pause times Fig. 5. Packet Delivery Ratio for different number of nodes

It is least for AODV and almost same for LAR1 and OLSR with slightly higher delay as depicted in fig.8 .

Packet delivery ratio is highest for AODV and almost constant for LAR1 and OLSRas depicted in fig.5.

Fig. 9. Average jitter for different pause times

It is least for AODV and almost 300 ms more in case of LAR1 and OLSR with OLSR performing slightly better than LAR1as suggested by fig.9.

Fig. 6. Signal Received but with error for different number of nodes

Fig. 6 suggests that signal received but with errors is least for LAR1 and highest for OLSR.

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[5]

Fig. 10. Packet delivery ratio for different pause times

Fig.10 Packet Delivery Ratio is highest for AODV and almost same for OLSR and LAR1.

[6]

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Fig. 11. Signal received but with error for different pause times. [10]

It is least for LAR1 and highest for AODV in high mobility conditions. As the mobility decreases OLSR shows most signal reception with errors. VI.

[11]

CONCLUSION

[12]

This paper evaluated the performance of four popular routing protocols for a mobile telemedicine scenario in WiMAX environment. It suggested that routing protocol LAR1 can offer better results in sending telemedicine data over wireless channel with high throughput and better reproducibility as signal received with error is least for LAR1 and throughput is highest in each test condition. For store and forward schemes it is best suited as it has inferior End to End delay and average Jitter are higher than AODV which presents as another alternative for such applications.

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VII. FUTURE WORK [18]

Further investigation for a better suited routing protocol for wireless healthcare applications can be carried out by taking data rates requirements from multiple sources considering more realistic geographical and fading model of the scenario concerned. A live traffic feed from healthcare device can also be tested and performance of network can be evaluated accordingly.

[19]

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