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Evaluation of the IEEE 802.11p-based TDMA MAC Method for Road Side-to-Vehicle Communications
Rashid A. Saeed,Amran Bin Hj Naemat,Azrin Bin Aris,Mat Kamil Bin Awang
International Journal of Network and Mobile Technologies , 2010,
Abstract: Wireless vehicular communications (WVC) has been identified as a key technology for intelligent transportation systems (ITS) for a few years ago. IEEE 802.11p is the proposed standard for physical and MAClayer of WVC devices. The main objective of the standard is to change the frame format and increase delay spread tolerance introduced by vehicle mobility, in which the channel bandwidth is scaled from 20 MHz i.e.802.11a to 10 MHz i.e. 802.11p. This paper proposes TDMA technique with fixed time slots and guard bandbetween slots to ensure interoperability between wireless devices communicate in rapidly changing environment where transactions must be completed in small timeframe. The new TDMA sub-layer is proposedto be on-top of the conventional 802.11p MAC. The simulation results present the performance analysis and validate the efficiency of the proposed scheme.
Propagation and Wireless Channel Modeling Development on Wide-Sense Vehicle-to-X Communications  [PDF]
Wenyi Jiang,Ke Guan,Zhangdui Zhong,Bo Ai,Ruisi He,Binghao Chen,Yuanxuan Li,Jia You
International Journal of Antennas and Propagation , 2013, DOI: 10.1155/2013/981281
Abstract: The need for improving the safety and the efficiency of transportation systems has become of extreme importance. In this regard, the concept of vehicle-to-X (V2X) communication has been introduced with the purpose of providing wireless communication technology in vehicular networks. Not like the traditional views, the wide-sense V2X (WSV2X) communications in this paper are defined by including not only vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications but also train-to-X (T2X) communications constituted of train-to-train (T2T) and train-to-infrastructure (T2I) communications. All the information related to the wide-sense V2X channels, such as the standardization, scenarios, characters, and modeling philosophies, is organized and summarized to form the comprehensive understanding of the development of the WSV2X channels. 1. Introduction Over the past few years, both the V2X and T2X have gained popularity in their attempts to improve road safety and railway safety, respectively. As shown in Figure 1, in order to form the comprehensive understanding, V2X and T2X are collected together to constitute the complete concept—wide-sense vehicle-to-X (WSV2X). The idea behind the WSV2X communications is the deployment of wireless communication technology in vehicular and railway networks. In this manner, the vehicles, trains, and infrastructures build up a wireless network enabling them to exchange controlling and traffic information, such as road obstacles, accidents, and so forth, via the wireless communication links. Figure 1: Block diagram of the constitution of the concept of wide-sense vehicle-to-X (WSV2X). Following are the situation of the standardization and the application related to WSV2X.(i)Intelligent transport systems (ITSs) [1] for V2X communications: ITSs are advanced applications which, without embodying intelligence as such, aim to provide innovative services relating to different modes of transport and traffic management and enable various users to be better informed and make safer, more coordinated, and “smarter” use of transport networks. In order to realize the ITSs, Institute of Electrical and Electronics Engineers (IEEE) and European Telecommunications Standards Institute (ETSI) have selected the same MAC and PHY layers for road traffic safety applications: IEEE 802.11p [2] and ETSI ITS G5 [3]. In the USA, in 1999, the Federal Communications Commission (FCC) allocated 75?MHz of licensed spectrum, from 5.85 to 5.925?GHz, as part of the ITS to use for Dedicated Short Range Communications (DSRC) [4]. Hence, IEEE
A TDMA-BASED MAC PROTOCOL SUPPORTING COOPERATIVE COMMUNICATIONS IN WIRELESS MESH NETWORKS  [PDF]
Hongzhi Jiao,Frank Y. Li
International Journal of Computer Networks & Communications , 2011,
Abstract: This paper proposes a TDMA-based medium access control protocol which enables cooperative communications in multi-hop wireless mesh networks. According to the proposed scheme, each router at the two-hop neighbourhood of each other is allocated to a specific time slot for accommodating either direct or cooperative transmissions in a coordinated manner, controlled by mini-slots which are part of the time slot. Benefiting from the elaborate mini-slot design, channel resources are fairly and efficiently allocated to each router so that no handshake is needed prior to each packet transmission. By providing access priority to cooperative transmission through an optimal relay which is determined by combined instantaneous relay channel conditions, higher system throughput can be achieved. To analyze the performance of the proposed cooperative protocol a Markov chain is introduced to model the behavior ofthe protocol. Simulation results demonstrate that the proposed MAC scheme can improve not only the one-hop transmission throughput but also the end-to-end throughput significantly. Moreover, the throughput performance of the proposed scheme is robust as packet size varies.
Pre-Emptive Traffic Management for a Cluster-Based TDMA System in Vehicular Communications  [PDF]
Nyoman W. Prasetya, Tsang-Ling Sheu, Achmad Basuki, Muhammad Aziz Muslim
Journal of Computer and Communications (JCC) , 2017, DOI: 10.4236/jcc.2017.51004
Abstract: The IEEE 802.11p is a standard in a vehicular communication system, known as Wireless Access in Vehicular Environment (WAVE). An implementation of that standard as the MAC Protocol in a high-density of nodes in Vehicular Ad-Hoc Networks (VANETs) may create a performance drawback, in particular for packet loss and delay whenever collisions happen. Introducing Time Division Multiple Access (TDMA) schemes can improve the performance. However, TDMA scheduling is difficult to manage the case of high-density of traffic, the high mobility of vehicles, and dynamic network topology. This journal proposes a clustered-based TDMA by traffic priority in VANETs. The clustered traffic is defined as high and low traffic priority and embedded in TDMA MAC Header. The evaluation result obtained through NS3 Simulator shows that the proposed approach performed better in a high-density of nodes.
Distance Dependence of Path Loss for Millimeter Wave Inter-Vehicle Communications
S. Takahashi,A. Kato,K. Sato,M. Fujise
Radioengineering , 2004,
Abstract: Millimeter-wave path loss between two cars was measured to obtainthe general applicable distance for inter-vehicle communication systemsin real environments. An abrupt and substantial increase in path lossdue to interruption, curves, and different-lane traveling has been amajor concern in inter-vehicle communications. The path lossmeasurements were carried out using 60-GHz CW radiowaves and standardhorn antennas on metropolitan highways and regular roads. Because thepropagation loss is traffic-dependent, the highways were classifiedinto uncrowded and crowded highways, and the regular roads wereclassified into uncrowded and crowded roads. The path loss for thehighways exhibited 2nd-power-law attenuation and that for the regularroads exhibited 1st-power-law attenuation with an increase ininter-vehicle distance. Additional losses of 15 dB for the highways and5 dB for the regular roads were observed when the inter-vehicledistance was more than approximately 30 m. Thus, we were able todemonstrate millimeter-wave inter-vehicle communications at aninter-vehicle distance of more than 100 m.
Impact of Mobile phone in the Air and Random Access Channel RACH with Time Division Multiple Access TDMA Noise in Aircraft Avionics  [PDF]
Siow Shyong Lau
Computer Science , 2014,
Abstract: Mobile phone 1800MHz band already allowed to be used in some airlines. Many studies talked about lower the mobile phone output power to the lowest of 0dBm, but seldom talk about the Random Access Channel RACH, which will emit at the highest power of 30dBm at the instant of call making and is not controllable until the connection between the Base Station and mobile is made.Hence the impact of RACH and TDMA noise generated in the aircraft.
Inter-Vehicle Wireless Communications Technologies, Issues and Challenges  [PDF]
S. Habib,M.A. Hannan,M.S. Javadi,S.A. Samad
Information Technology Journal , 2013,
Abstract: Wireless communication technologies have emerged vehicular networks in the forms of Intra-Vehicle (InV), Vehicle-to-Vehicle (V2V) and Vehicle-to- Infrastructure (V2I) communications. These technologies enable a variety of applications for driver and passenger needs, such as safety, convenience and entertainment facilities incorporated into modern automobile designs. The researchers exploit the different services that will enable to exchange useful information with-inside and with-outside vehicle via vehicular networks. Vehicles exchange information about their state, view of current road, navigation information and other general information about weather report and digital map update. A key for exchanging information in timely manner is an opportunity to access the medium for longer life with low power consumption in various ranges. They provide high reliability without experiencing long and uncertain delay. Thus, widespread adoption of vehicular networks is fast becoming a reality, where additional functions will be provide by the car electronics and the passengers will be able to access the Internet and other core network resources. This study presents an overview of the potential wireless technologies for data exchange in a various ranges, its current research activities, issues and challenges that exist in each wireless technology.
A Mobile Edge Computing Approach for Vehicle to Everything Communications  [PDF]
Plouton V. Grammatikos, Panayotis G. Cottis
Communications and Network (CN) , 2019, DOI: 10.4236/cn.2019.113006
Abstract: This paper explores the exploitation of Mobile/Multi-access Edge Computing (MEC) for Vehicle-to-Everything (V2X) communications. Certain V2X applications that aim at improving road safety require reliable and low latency message delivery. As the number of connected vehicles increases, these requirements cannot be satisfied by technologies relying on the IEEE 802.11p standard. Therefore, the exploitation of the 4th generation Long Term Evolution (LTE) mobile networks has been considered. However, despite their widespread use, LTE systems are characterized by high end-to-end latency since the messages have to traverse the core network. MEC addresses this problem by offering computing, storage and network resources at the edge of the network closer to the end-users. This paper aims at investigating the benefits MEC may offer toward implementing V2X communications. In this framework, simulation scenarios were examined concerning various V2X use cases implemented employing either LTE or MEC. The simulation results indicate a clear superiority of MEC over LTE, especially in the case of delivering critical data.
Basis of self-organized regulation resulting from local communications  [PDF]
Mayuko Iwamoto,Daishin Ueyama
Physics , 2015,
Abstract: Proportion regulation in nature is realized through and limited to local communications. One of the fundamental mysteries in biology concerns the method by which a cluster of organisms can regulate the proportion of individuals that perform various roles as if each individual knows a whole situation, without a leader. This study focused on the fact that regulating system exists in various species, and found a common basis which is described by a series of local communications between individuals with creature-likeness. The most essential behavior of individuals in this theory is to change its internal mode through sharing information in communication with others. Our numerical simulations with cellular automata model realize to regulate the ratio of population of individuals who has either two kinds of modes. From the theoretical analysis, we found that asymmetric properties in local interactions originated from difference of parameter values in communication are crucial for adaptive regulation, which depends on overall density. Furthermore, the critical condition which eliminates overlap with one another (excluded volume effect) also affects the resulting proportion in high density. The foremost advantage of this strategy is that no global information is required for each individual, and only a couple of transformations for each individual can achieve the whole proportion regulation. Our simple mechanism has a potential to solve various phenomena that microscopic individuals behaviors connect to macroscopic orderly behaviors.
Superiority of TDMA in a Class of Gaussian Multiple-Access Channels with a MIMO-AF-Relay  [PDF]
Frederic Knabe,Omar Mohamed,Carolin Huppert
Mathematics , 2012,
Abstract: We consider a Gaussian multiple-access channel (MAC) with an amplify-and-forward (AF) relay, where all nodes except the receiver have multiple antennas and the direct links between transmitters and receivers are neglected. Thus, spatial processing can be applied both at the transmitters and at the relay, which is subject to optimization for increasing the data rates. In general, this optimization problem is non-convex and hard to solve. While in prior work on this problem, it is assumed that all transmitters access the channel jointly, we propose a solution where each transmitter accesses the channel exclusively, using a time-division multiple-access (TDMA) scheme. It is shown that this scheme provides higher achievable sum rates, which raises the question of the need for TDMA to achieve the general capacity region of MACs with AF relay.
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