Enhancement of VANET Communication Range using WiMAX and Wi-Fi: A Survey

International Journal of Urban Design for Ubiquitous Computing Vol.1, No.1, (2013), pp. 9-16 http://dx.doi.org/10.21742/ijuduc.2013.1.1.02 Enhancement of VANET Communication Range using WiMAX and Wi-Fi: A Survey Priyanka Tiwari 1, and Rajendra Singh Kushwah 2 1,2 Department of Computer Science and Engineering Institute of Technology & Management, Gwalior-India tiwari23priyanka@gmail.com, rajendrasingh.ind@rediffmail.com Abstract In recent years, VANET (Vehicular Ad-hoc Network) have become an orientation to the researchers enhancing the comfort and facilities to the driver and passengers both. Daily, several unexpected accidental situations are encountered on the roads that cause a lot of damage to the vehicle and road. Sometimes it is dangerous for the human life. It aimed at providing the security and safety to the driver and vehicle both by providing continuous connectivity between the on board units (OBUs) in vehicles and road side units (RSUs), so vehicles stay always connected with the other vehicles. VANET disseminates the information in advance about such type of accidental and disastrous situations. Due to extreme mobility in VANET a frequent connection break occur among vehicles is resolve by using Wi-Fi which provides faster and reliable connection for mobile stations and WiMAX for high speed transmission of data for fixed stations. Keywords: VANET, Wi-Fi, WiMAX, RSU, OBU, V2V, V2I and V2V2I 1. Introduction VANET represent a rapidly emerging research field and are considered essential for broader range of large scale, highly mobile applications. It provides a massive environment where the communication establishes amidst the vehicles and Road side units (RSUs), information is exchanged wirelessly without having fixed infrastructure. Information dissemination contains the alert messages for the drivers about the condition of the road and other threatening issues. Some safety related services like traffic congestion alarm, road blockage, collision warning are also addressed by VANET. In the other category of comfort related services are location based services, traffic management information, automated toll payment, Data transfer and infotainment applications providing access to the internet connectivity. VANET is one of the type of Mobile ad-hoc network (MANET) consisting of mobile nodes due to which frequent path break occur. In VANET, each RSU has a region consist of number of moving vehicles constitutes a cell which means a range of wireless signal. In this, each vehicle function as a router to another vehicle so it can further disseminate signals and act as repeater which consider every vehicle as a base station to the other vehicles to disseminate information. VANET mainly consist of two types of communication- vehicle to infrastructure (V2I) vehicle to vehicle (V2V) communication through which wireless product or vehicles connect. Article history: Received (May 10, 2013), Review Result (July 17, 2013), Accepted (August 13, 2013) ISSN: 2205-8605 IJUDUC Copyright c 2013 GV School Publication

Enhancement of VANET Communication Range using WiMAX and Wi-Fi: A Survey Figure 1. Vehicular ad network (VANET) infrastructure Each vehicle has its built in device called On Board unit (OBU)/ Radio interface that enables short range wireless ad-hoc network which receives safety messages like sudden break warning from other vehicles, accident annunciation etc., and non safety message like entertainment related information. Road side units (RSUs) are the access points used together with the vehicles to allow information dissemination on the roads. In this vehicular environment Wi-Fi and WiMAX are used as RSUs. It consider safety applications using short range wireless technologies like Wi-Fi or Wireless access in vehicular ad-hoc network (WAVE), depending on the type of interaction occur among the vehicles. Other non-safety applications are also raise the efficiency of vehicle and road. Furthermore, vehicles can connect to the other infrastructure networks called Road side units, WiMAX or cellular network. As shown in Fig.1, the interaction among vehicles and with RSUs is enabled by Wi-Fi hotspot and WiMAX tower respectively. WiMAX technology is generally used for providing the internet facility through its tower and antennas for long or wide range of communication [1], [2]. Vehicles can easily and always access internet, so that they are always up-to-date about the roadways map, condition of the road, any accidental situation occur on that path, nearest restaurants and petrol pumps. 2. Characters VANET do not swear on fixed infrastructure for communication and dissemination of information among the vehicles. Some VANET characteristics are [3], [4], and [5]: Highly Dynamic Topology: VANET has highly dynamic environment due to the fast movement of vehicles, the topology continuously changes. Vehicle can join and leave the radio range very frequently. Generally the radio range of vehicles is about 300 m (radius of 150m). Frequent Disconnected Network: Due to the highly dynamic topology frequent disconnection occurs (it especially happens when the density of vehicles is low) between two vehicles when they are exchanging information. This disconnection shall occur mostly in highways because of sparse area. Communication Environment: VANET generally consist of two types of environment sparse network and dense network. In dense network, there are many obstacles like tree, buildings, and others which reduce signal range and data 10 Priyanka Tiwari and Rajendra Singh Kushwah

International Journal of Urban Design for Ubiquitous Computing Vol.1, No.1, (2013), pp. 9-16 transmission speed among Vehicles and RSUs. But, in case of sparse network, all these obstacles are absent and do not affect the direct connectivity of vehicles. Unlimited Storage Capacity and Transmission Power: Modern vehicles consist of large storage capacity, so they can store routing information, driver s and vehicles identity proof and other data. Vehicles itself provide continuous power to the OBUs for the communication Interaction with Onboard Sensors: In VANET, each vehicle is equipped with onboard sensors to provide the information like their position, identity and other vehicle related information which can be used for the communication purpose. For example, GPS receivers are used in vehicles to provide location information for routing purpose [8]. High Computational Capability: Vehicles consist of high computational capabilities, i.e. capability of sensing and communicating with the vehicles. Decentralized: The orientation of VANET network consist of decentralization, there is no central node or hub which can controls all the other participating vehicles. Each vehicle is independent in the network. 3. Challenges of VANET In recent era, VANET facing many challenges that require further exploration and innovation to get the best solutions for VANET infrastructure, security, applications and services. Some of the VANET challenges are given below: High Mobility: Due to high speed of vehicles, connections are quickly formed or disconnected. Mobility model of vehicles depend on driver s behavior, traffic environment (sparse or dense network), road structure and vehicle speed. Volatility: The connectivity in vehicular environment is for short period of time. Vehicles may fall or out of the coverage range of other vehicle due to high mobility. Security and Privacy: Security and privacy are also required in VANET for driver and vehicle both. The lack of fixed infrastructure, nodes in VANETs rely on other nodes which are unreliable to propagate data [6]. Fake messaging should be detected and enforcement of anonymous behavior for unreliable persons to prevent vehicle tracking and identification. Privacy of car driver is necessary. They may want to keep their information and location private from unauthorized persons. Liability: It is very useful during the legal investigation and this data cannot be denied in case of any fraud or accidental damage. But by providing the liability, privacy must be violated. 4. Problem Formulation In VANET, Wi-Fi and WiMAX are used to provide connectivity and media distribution among the vehicles and infrastructure. They implement V2V, V2I and V2V2I communication networks with enhancing the range of both vehicle and RSUs. They consider IEEE 802.11 g/n (Wi-Fi) and 802.16 (WiMAX) to disseminate non safety applications, location of the vehicles, infotainment applications etc. After the practical implementation of network architecture (V2V2I) in VANET environment, the range of Wi-Fi is reached about 300m (150 m both sides) in wireless local area network (WLAN) technology based on the IEEE 802.11 network standard operating on an unlicensed radio frequency of 2.4 GHz which is offering 150 Mbps of maximum data rate for the vehicles following each other, but in case of the vehicles moving in opposite direction the data rate becomes very less [7]. Copyright c 2013 GV School Publication 11

Enhancement of VANET Communication Range using WiMAX and Wi-Fi: A Survey On emulation of Wi-Fi and WiMAX in [7] used WiMAX covering the range of about 50 km, operating on both licensed ((10-66 GHz) and unlicensed (5-6 GHz) band in Metropolitan area network (MAN) technology base on IEEE 802.16 standard, by using fixed WiMAX towers that are located on the top of buildings. In [7], WiMAX throughput used for V2I communication, is sternly affected by even slight mobility, this is due to the use of fixed wireless communication standard 802.16 d, which is especially designed for the fixed base towers. This cannot work properly in mobile environment, if the mobility occurs in WiMAX, the error rate increases which affect the throughput for NLOS but doesn t significantly affect the average throughput of the network. Wi-Fi support HD video, large data file transfer because of its higher data rates in V2V communication. But the WiMAX doesn t significantly work for higher data rates. It is suitable for the applications like streaming audio and video, video conferencing and sending small data files. This all work done only for two vehicles that they communicate with each other providing the environment with no collision and contention. This is the problem while implementing the setup in real world. In practical, there are several vehicles, obstacles on the roads which will affect the throughput, data rate, connection time and other parameters. In this, we will survey the most recent study on the deployment of Wi-Fi and WiMAX in VANET efficiently, so that the range of Wi-Fi hotspot and WiMAX tower improved. 5. Literature survey There are several works which have been carried out in the area of VANET using Wi-Fi and WiMAX for providing continues connectivity among the vehicles and infrastructure base stations. Evaluation of multivehicle to infrastructure (V2V2I) VANET using Wi-Fi for V2V communication and V2I is experimented in [7]. [8] reviewed some of the main areas of VANET including status, result and challenges and highlighted the most salient results achieved. Some areas of the literature are, the communication architecture that is used in VANET, wireless technology that are used to establish link between the vehicles and infrastructure in vehicular environment. 5.1. Communication Architecture in VANET VANET consist of several network architectures which organize and develop the wireless network. Mainly there are three types of network systems for establishing the communication among the vehicles, Vehicle to vehicle (V2V) or vehicle to roadside (V2R), vehicle to infrastructure (V2I) and multi vehicle communication called vehicle to vehicle to infrastructure communication (V2V2I). It includes RSU s existing along the road and vehicle equipment called on board unit (OBU) and some application units (AP) executing a single or a set of applications [5]. Figure 2 shows the communication types of network architecture, presenting V2V, V2R and V2V2I communication. It also consists of OBUs and RSUs, which can be classified as nodes in VANET. OBUs are used for representing the mobile nodes such as vehicle and RSUs for the static nodes, base towers. 12 Priyanka Tiwari and Rajendra Singh Kushwah

International Journal of Urban Design for Ubiquitous Computing Vol.1, No.1, (2013), pp. 9-16 Figure 2. Communication Network in VANETs: V2V, V2I/V2R and I2V Communication OBUs are built in vehicles to receive or transmit the signal information between the vehicles and RUSs provide them signal range or the internet connectivity with distributed environment because of the absence of centralized based station. RSU s are linked with the network infrastructure which is connected to the internet. As a result it may permit OBUs to access infrastructure [7]. 5.1.1. Vehicle to Vehicle Communication (V2V): Figure 3 represent vehicle to vehicle communication, the communication done either directly between the vehicles as single hop communication or it can uses multicast or broad cast routing techniques to disseminate information to a group of receivers over multiple hops. V2V communication consisting of two type message forwarding - naive broadcasting and intelligent broadcasting [8]. In naive broadcasting vehicle send information after a regular interval of time. If the message comes from its ahead vehicle, then the receiving vehicle accepts the message and broadcast its own message, but if it is from a vehicle behind it then it discard the message. In case of intelligent broadcasting, messages with implicit acknowledgement are forwarded. Probability of message collision increases because of large numbers of messages send, which decreases the data rate speed and increases the time to send the data. [8], [9]. Figure 3. Vehicle to vehicle communication Copyright c 2013 GV School Publication 13

Enhancement of VANET Communication Range using WiMAX and Wi-Fi: A Survey It overcomes the problem of naive broadcasting, in which the message comes from behind vehicle are ignored, but if the message comes from in front, the receiving vehicle send its own message to the behind vehicles. This ensures that all the enabled vehicle moving in forward direction get all broadcast messages [8]. 5.1.2. Vehicle to infrastructure (Roadside) communication (V2V OR V2R): V2R communication is shown in Figure 4, road side unit (RSU) broadcast the message to all the nearest vehicles that are equipped with it i.e., represents a single hop broadcast. It deliver high bandwidth link between vehicles and RSUs. RSUs are placed after regular distance, which allows high data rates to be maintained in large traffic. Relays at the roadside can be deployed to enhance the robustness and coverage of communication [8]. Figure 4. Vehicle-to-roadside communication 5.1.3. Vehicle to Vehicle to Infrastructure Communication: Vehicle to vehicle to infrastructure communication is the hybrid of both V2V and V2I communication, consist of vehicles communicate through the intermediate vehicles or infrastructure. If a vehicle A want to send information to the other vehicle B which is far distance from vehicle A, then it send information to its nearest RSU or infrastructure base station and by using internet it transmit the information to the infrastructure nearest to vehicle B, finally the information reach to the destination vehicle B. 5.2. Wi-Fi and WiMAX in VANET Wi-Fi and WiMAX are the two recently used wireless technologies for establishing the connection among the vehicles, RSUs and infrastructure towers. Each technology has its benefits and limitations over each other. 1. Wi-Fi- Wi-Fi uses a Wireless Router or Repeater to expand its wireless coverage area. It belongs to the family of IEEE 802.11 is specifically designed for mobile users, such as for vehicles in vehicular environment. Wi-Fi provides short communication range. The mobility of vehicle does not affect Wi-Fi speed or connection. 2. WiMAX- Worldwide interoperability for Microwave Access (WiMAX) uses cells of fixed and mobile towers called "Base Stations". It generally used for providing a large range of communication. In VANET, WiMAX towers are situated at the top of building or any high base station. 14 Priyanka Tiwari and Rajendra Singh Kushwah

International Journal of Urban Design for Ubiquitous Computing Vol.1, No.1, (2013), pp. 9-16 Figure 5. V2V2I setup for vehicles (a) crossing each other (b) following each other V2V2I communication using both Wi-Fi and WiMAX For different VANET network architectures, in [7] evaluation of the performance of Wi-Fi (IEEE 802.11 g/n) and WiMAX (IEEE 802.16 d for fixed towers) for based on measurements of throughput, contact time, data rate, received signal strength, jitter and total data transferred [5]. The previous experiments involved measuring the amount of data transferred during the short period of connection time. It includes all the results occur with vehicle following each other in the same or opposite direction and calculates the throughput, data rate connection time and other measurements. Both the TCP and UDP protocols are utilized with the packet size depend on the total data transferred. Wi-Fi uses Line of sight (LOS) to maintain V2V communication because of its short range. WiMAX consist of both LOS and Non Line of Sight (NLOS) conditions in V2I or V2R communication environment. V2V2I communication utilized both Wi-Fi and WiMAX, which means it operated under LOS and NLOS conditions [7], [9]. A. The following major comparisons are involved the WiMAX and Wi-Fi after the analysis of [7], [9]: Table. Wi-Fi and WiMAX comparison Wi-Fi WIMAX Connection type Connection oriented Connection less Range Frequency 300 m Lower 2.4 GHz 50 km for fixed station 5-15 km mobile Data rate 150 Mbps 54 Mbps Higher 5-6 GHz (unlicensed) 10-66 GHz (licensed) Access point Limited No. of users Reliability Reliable Unreliable Family 802.11 802.16 Provide communication V2V V2I Copyright c 2013 GV School Publication 15

Enhancement of VANET Communication Range using WiMAX and Wi-Fi: A Survey Work on NLOS LOS NLOS Jitter less Less High 6. Conclusion VANET have become most popular solution in computing, telecommunication (fixed and mobile stations) and other infotainment services that are enabled by various VANET technologies. The enormous deployment of V2V, V2I and V2V2I communication networks are used for efficiently transferring the data with reliability. Feasibility of infotainment applications in VANET depend on the communication medium, network and its characteristics. In this, Wi-Fi and WiMAX both are utilized for the different purpose, as Wi- Fi provide the short range communication in V2V with reliability and WiMAX for V2V communication reaching a long range using IEEE 802.11 and IEEE 802.16d standards respectively. Wi-Fi ranges up to 300m were achieved with external antennas. References [1] A. A. Mansour, N. Enneya, M. Ouadou and D. Aboutajdine, Handoff between WiMAX and Wi-Fi Networks, IEEE, pp. 69-74, (2012). [2] L.S. Mojela and M.J. Booysen, On the use of WiMAX and Wi-Fi to provide in-vehicle connectivity and media distribution, IEEE, pp. 1353-1358, (2013). [3] B. Paul, Md. Ibrahim and Md. A.N. Bikas, VANET Routing Protocols: Pros and Cons, International Journal of Computer Applications, vol. 20, no. 3, (2011) April, pp. 28-34. [4] F. Li and Y. Wang, University of North Carolina at Charlotte, Routing in Vehicular Ad Hoc Networks: A Survey, IEEE Vehicular Technology Magazine, (2007) June. [5] K. Prasanth, K. Duraiswamy, K. Jayasudha and C. Chandrasekar, Reducing Packet Transmission Delay in Vehicular Ad Hoc Networks using Edge Node Based Greedy Routing, International Journal of Computer Networks, vol. 2, no. 1, 1, pp. 1-15. [6] A. Dhamgaye and N. Chavhan, Survey on security challenges in VANET, IJCSN International Journal of Computer Science and Network, vol. 2, no. 1, 88, (2013), pp. 2277-542. [7] L.S. Mojela, On the use of WiMAX and Wi-Fi in a VANET to Provide in-vehicle Connectivity and Media Distribution, Thesis, Stellenbosch University http://scholar.sun.ac.za, (2011) December. [8] S. Zeadally, R. Hunt, Y.S. Chen, A. Irwin and A. Hassan, Vehicular ad hoc networks (VANETS): status, results, and challenges, Springer Science+Business Media, LLC, (2010). [9] M.R. Arshad, S. Mehmood, S. Afsar, M.A. Zia and U. Farooq, An Evaluation study of WiMAX and Wi-Fi on Vehicular Ad-Hoc Networks (VANETs), International Journal of Scientific & Engineering Research, vol. 3, no. 12, (2012) December, pp. 1-7. 16 Priyanka Tiwari and Rajendra Singh Kushwah