Geo Based Vehicular Adhoc Network Protocol and Dynamic Slot Allocation

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1 Geo Based Vehicular Adhoc Network Protocol and Dynamic Slot Allocation Sekhar Dunna 1 Tatapudi Prabhakara Rao 2 1 Final Year M.Tech Student, Dept. of CSE, Aditya Institute of Technology and Management(AITAM), Tekkali, Srikakulam, Andhra Pradesh 2 Sr.Asst.Professor, Dept. of CSE, Aditya Institute of Technology and Management(AITAM), Tekkali, Srikakulam, Andhra Pradesh Abstract:- An Medium access control (MAC) implementation in Vehicular adhoc network is still an important research issue because it is a vehicle traffic optimization approach. Even though various available with traditional approaches they are not optimal because of vulnerabilities during the broadcasting, we need an efficient and a novel broadcasting mechanism for vehicular adhoc networks, road side units which periodically broadcasts the signals either wired or wireless. We are optimizing each vehicle decides whether or not it is allowed to access the channel based on its location on the road in efficient manner. Our experimental results shows broadcasting of packets based on the Service request, broadcast range and priority and efficiently handles during the collision of the nodes when they are within range and same transmission range of packets and time. Index terms: On Board Unit, Road Side Unit, Broadcasting, Vehicular adhoc network. I.INTRODUCTION There is a rapid increase of vehicle along with millions of population and increase of death cases every year even though various traffic rules are set for safety of people. Vehicular Adhoc Networks (VANET) should upon implementation collect and distribute safety information to massively reduce the number of accidents by warning drivers about the danger before they actually face it. Such networks comprise of sensors and On Board Units (OBU)installed in the car as well as Road Side Units(RSU) and the data collected from the sensors on the vehicles can be displayed to the driver broadcasted to other vehicles depending on its nature and importance and the RSU distributes this data along with data from road sensors weather forecasting centers, other traffic control centers and other to the vehicles and also provides commercial services such as parking space booking along with Internet access and gas payment and the network makes extensive use of wireless communications to achieve its goals but although wireless communications reached a level of maturity and a lot more is required to implement such a complex system. Most available wireless systems rely on a base station for synchronization and other services however using this approach means covering all roads with such infrastructure which is impractically too expensive. Adhoc networks have been studied for some time but VANET will form the biggest adhoc network ever implemented, therefore issues of stability, scalability and reliability are main concern VANET therefore is not an architectural network and not an adhoc network but a combination of both of this unique characteristic combined with high speed nodes complicates the design of the network [1][4][5]. Most VANET applications consider the availability ofreal-time updated position information. They differ, however, on the localization accuracy required in order to beable to function properly. For instance, some applications can work with inaccurate localization information in which computed positions can have errors from 10 to 20 or 30 m, while other applications, especially critical safety applications, require more accurate and reliable localization systems with sub-meter precision. In this section, we divide VANET applications into three main groups according totheir localization requirements and show how position information is used by these protocols and algorithms [2][7]. Dedicated Short Range Communication (DSRC) refers to the use of vehicle-to-vehicle and vehicle-toinfrastructure communications to improve road safety and increase transportation efficiency. Among the many candidate applications, cooperative collision avoidance (CCA) has attracted considerable interest in the research community as it can significantly improve road safety. In CCA, moving cars form a network to wirelessly communicate and warn each other of changing conditions or dangers ahead on the road to avoid accidents.this application requires timely communication of safety messages between vehicles with high reliability, and the medium access control (MAC) protocol has a vital role to play. VariousMAC protocols have been proposed for vehicle-to-vehicle communications in the research literature [3][8]. II. RELATED WORK The VANET under consideration consists of a set of RSUsand a set of vehicles moving in opposite directions on two way vehicle traffic roads [6]. A vehicle is said to be ISSN: Page 293

2 moving in aleft (right) direction if it is currently heading to anydirection from north/south to west/east Based on this definition, if two vehicles are moving inopposite directions on a two-way road, it is guaranteed that one vehicle is moving in a left direction while the othervehicle is moving in a right one.the VANET has one control channel, denoted by c 0, and M service channels, denoted by c 1,c 2,...,c M. Channel c 0 isused for transmission of two kinds of information: high priority short applications (such as periodic or event driven safety messages) and control information required for the nodes to determine which time slots they should access on channel c i, i= 0,...,M. The M service channels are used for transmission of safety or non safety related application messages [7][9]. w y z x x Collision Fig1 : Merging Collision caused by Node mobility A provider is a node which announces on channel c0 for a service offered on a specific service channel, while a user is a node which receives the announcement for a service and decides to make use of this service. Each node has two transceivers: Transceiver 1 is always tuned to channel c 0, while transceiver 2 can be tuned to any service channel c i ; i = 1,...,M. It is assumed that the transmission power levels on all channels are fixed and known to all nodes. All channels are symmetric, in the sense that node xis in the communication range of node y if and only if node y is in the communication range of node x. Each node is identified by a MAC address as well as a short identifier (ID). The ID is chosen by each node at random, included in the header of each packet transmitted on channel c 0, and changed if the node detects that its ID is already in use by another node [4]. Time is partitioned to frames consisting of a constant number of fixed duration time slots. The number of time slots per frame on channel cm is denoted by s m,m = 0,...,M, and a time slot on channel cm is identifiedby the index of this time slot within a frame on channel c m.on channel c 0, each frame is partitioned into three sets oftime slots: L, R, and F. The F set isassociated with RSUs, while the L and R sets are associated with vehicles moving in left and right directions, respectively.every node (i.e., vehicle or RSU) is equipped with a global positioning system (GPS) receiver and can accurately determine its position and moving direction using GPS. The current position of each node is included in the header of each packet transmitted on channel c0, and synchronization among nodes is performed using the 1PPS signal provided by any GPS receiver [10]. The rising edge of this 1PPS is aligned with the start of every GPS second with accuracy within100 ns even for inexpensive GPS receivers. Consequently, this accurate 1PPS signal can be used as a common time reference among all the nodes. All the channels are slot synchronized and, on each channel, each second containsan integer number of frames as shown in Fig. 2 for channelc0. Hence, at any instant, each node can determine the index of the current slot within a frame on any channel c m, m =0,...,M, and whether it belongs to the L, R, or F set on channel c0. In case of a temporary loss of GPS signal, the synchronization among different nodes can still be maintained within a certain accuracy for a time duration, which depends on the stability of the GPS receiver s local oscillator at each node If the GPS signal is ISSN: Page 294

3 lost in a certain area for a long duration (longer than a specified threshold), a distributed synchronization scheme, such as the one presented in,should be employed until the GPS signal is recovered[11][12]. II. PROPOSED WORK In this paper we are proposing an efficient collision free broadcasting approach with dynamic slot allocation table and geo codings based mechanism for computing the distance between the on board units and if distance exceeds the minimum distance, here every onboard unit can be identified by geo parameters (latitude and longitude), messages can be broadcasted to other On board units and road side unit broadcasts the packets whenever a new data packets available at its end.when any OBU receives data packet request initially it checks slot allocation table, if allocation table is free,it updates allocation table with onboard unit id and data packets else it increases the allocation table size dynamically whenever required OBU RSU Broadcast Position by latitude and longitude Fig 2 : Architecture Every On Board Unit in the vehicle can be identified by the geo-codings (Latitude and longitudes) of the vehicle positions and it measures the distance between the OBU to OBU and OBU of the Vehicle receives the data packets which are broadcasted by the Road side unit. On Board Unit is the communication device in the vehicle, communicates with other on board units and Road side units. Receives and send data packets from the OBU and it receive data packets from RSU. Our protocol supports OBU data packet transmission, based on transmission range to everyone on board unit communicates efficiently without any collision with their channels. When a node or vehicle x tries to communicate with other node y with in transmission range, Node x allocate the free slot for node y to make it collision free and communicate based on the channel allocation table maintained at the node. For allocation of nodes computes the distance between the nodes with their geo-codings, based on the distance allocate the slot for the node. In the above algorithm Set N represents set of nodes or vehicles which has on-board units; OBUs can transmit and the ISSN: Page 295

4 following algorithm shows efficient broadcasting and dynamic slot allocation as follows. Geo Based Broadcasting and Collision Handling Input: N(N1,N2,..Nn) G(g1(x1,y1),g2(x2,y2) gn(xn,yn)) OBU(OBU1,OBU2,.OBUn) RSU(RSU1,RSU2..,RSUn) Output: Collision free & optimal communication between OBUs & RSUs Step1: initiate nodes N, on board unit(obu) and road side unit(rsu) Step2: while(free) Receive msg:=msg(obui) Step3: get geocode(g1,g2,g3..gn) from active nodes Step4: Compute Euclidian distance between two nodes E= (x2-x1)2+(y2-y1)2 Step5: get Min distance Step6: if(mindis< threshold value) Send msg to OBU Else Ignore msg Collision Handling Step1: Initiate the allocation of nodes Step2: Check slot availability of input node If(slot available) units to broadcast data packets to nearest OBUs whenever update available. Message can be received by any node whenever Euclidean distance between two nodes is minimum or other on board unit meets minimum threshold value set in on board unit which is calculated with geo-codings of OBU1 and OBU2 like ( , ) and (325621, ). Update slot table Step3: prioritize the nodes based on single hop &multi-hop Step4: transmit msg to OBU and update allocation table receives the data packets from other on board units and road side units. G indicates set of geo parameters or location parameters of the vehicles, RSUs are the road side Every OBU always be in listening mode whenever a message received at allocation table, updates slot allocation table dynamically and computes Euclidean distance if exceeds minimum threshold broadcast message to respective OBUs, whenever message received by receiver OBU, it can be removed instantly from allocation table. EXPERIMENTAL ANALYSIS For experimental implementation we had used Network or socket programming in C#.net.Consider an example of five on board units OBUs {OBU1, OBU2, OBU3,OBU4, OBU5} and two Road side units RSUs {RSU1,RSU2}. Individual on board units consists of allocation table which contains Source node, message and time stamp. Allocation table is dynamic and it can increase allocation table size automatically whenever it reaches its maximum size to make collision free communication and continuously forwards messages to view panel with time stamp and releases from allocation table immediately. Allocation tables shows as follows Priority Node Message Time Stamp 3 OBU2 Min Dist Reached 09 : 09:14 6:50 pm 1 OBU3 Min Dist Reached 09 : 09:14 7:00 2 OBU4 Min Dist Reached 09 : 09:14 7:00 E.D=Math.Sqrt((x2-x1)2+(y2-y1)2) If Euclidean distance not satisfies with minimum distance message can be fired to respective nodes and checks allocation table, if it reaches maximum size increases allocation table size dynamically and updates message and then transmits to view panel to the end user. ISSN: Page 296

5 Our experimental results shows efficient results than the traditional approach as follows Throughput (packet/slot) Low Med High Very high Traditional Proposed The above graph shows traffic level in x axis with different density levels like low, medium, high and very high and in y axis percentage of traffic collision, the following status or report of graph generated when a node or on board unit transmits messages to allocation table for its slot, if it is busy expand the allocation table dynamically, so at any level it maintains consistency. The experimental results shows more performance over traditional approaches when the density of the land is either low, medium or high because our approach work towards collision free with dynamic allocation and increases the performance by forwarding the data packets to on board unit which has minimum Euclidean distance. IV. CONCLUSION AND FUTURE WORK We are concluding our research work with efficient broadcasting protocol and dynamic allocation table updating whenever allocation table exceeds its maximum size and dynamically computes distance between on board units and forwards data packets to Other OBUs but priority based on Euclidean distance. We can enhance our concluded work by enhancing or identifying packet error rate and acknowledgement from the receiver node whenever a successful transmission or failure happened while transmission of data packet. REFERENCES [3] Performance Analysis of the IEEE MAC Protocol for DSRC with and without Retransmissions Md. Imrul Hassan, Hai L. Vu and Taka Sakurai. [4] VeMAC: A TDMA-Based MAC Protocol for Reliable Broadcast in VANETs Hassan Aboubakr Omar, WeihuaZhuang and Li Li. [5] R. Mangharam, R. Rajkumar, M. Hamilton, P. Mudalige, and F. Bai, Bounded-Latency Alerts in Vehicular Networks, Proc. Mobile Networking for Vehicular Environments, pp , May [6] F. Watanabe, M. Fujii, M. Itami, and K. Itoh, An Analysis of Incident Information Transmission Performance Using MCS/ CDMA Scheme, Proc. IEEE Intelligent Vehicles Symp. (IV 05), pp , June [7] H. Nakata, T. Inoue, M. Itami, and K. Itoh, A Study of Inter Vehicle Communication Scheme Allocating PN Codes to the Location on the Road, Proc. IEEE Intelligent Transportation Systems Conf. (ITSC 03), vol. 2, pp , Oct [8] IEEE Std p-2010, Standard for Information Technology- Telecommunications and Information Exchange between Systems-Local and Metropolitan Area Networks-Specific Requirements Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications Amendment 6: Wireless Access in Vehicular Environments, IEEE, pp. 1-51, July [9] IEEE Std (Revision of IEEE Std ), Standard for Information Technology Telecommunications and Information Exchange between Systems-Local and Metropolitan Area Networks- Specific Requirements - Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, IEEE, pp , June [10] M. Hassan, H. Vu, and T. Sakurai, Performance Analysis of the IEEE MAC Protocol for DSRC Safety Applications, IEEE Trans. Vehicular Technology, vol. 60, no. 8, pp , Oct [11] S. Eichler, Performance Evaluation of the IEEE p WAVE Communication Standard, Proc. IEEE 66th Vehicular Technology Conf. (VTC 07-Fall), pp , Oct [12] F. Borgonovo, A. Capone, M. Cesana, and L. Fratta, ADHOC MAC: New MAC Architecture for Ad Hoc Networks Providing Efficient and Reliable Point-to-Point and Broadcast Services, Wireless Networks, vol. 10, pp. BIOGRAPHIES Sekhar Dunna completed M.Sc., degree in Computer Science from Annamalai University and He is pursuing M.Tech degree in the Department of Computer Science and Engineering, from Aditya Institute of Technology And Management. Tatapudi Prabhakhara Rao completed his B.Tech Computer Science & Engineering from jntu Hyderabad. He completed M.Tech Computer Science & Engineering from Jntu Kakinada. Area Of Interstest: Image Processing, Wireless Sensor Networks, Mobile Computing, Network Security. He Is member Of CSI, ISTE & IE. [1] Current Trends in Vehicular Ad Hoc Networks Ghassan M. T. Abdalla*, Mosa Ali Abu Rgheff*and Sidi Mohammed Senouci** [2] Vehicular Ad Hoc Networks: A New Challenge for Localization- Based Systems q Azzedine Boukerche a,*, Horacio A.B.F. Oliveira a,b,c, Eduardo F. Nakamura b,d, Antonio A.F. Loureiro. ISSN: Page 297