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Below the Media Access Control (MAC) layer is the Physical (PHY) layer which deals with the actual transmission of the bits received from the MAC layer above into electromagnetic signals. This layer is optimized to implore power management in wireless networks. Power management is a crucial issue in wireless and mobile networks. In this paper, we propose an Adaptive Context-Aware Rate Selection (ACARS)...
Cellular operators have concluded that small cell deployments are a very cost-effective and quick solution to meet the ever growing demands on capacity and coverage in cellular networks for indoor and outdoor environments. While traveling in public transit vehicles, cellular subscribers usually experience poor signal reception and low bandwidth. We hence consider deploying small cells onboard (i.e...
In this paper, we present the statistical and the dynamical model of radio propagation channel at 5.9GHz band for vehicle to vehicle communication. The measurements were done in a real underground mine gallery.
Vehicular ad hoc network (VANET) is a type of promising application deployed along a road for communication, safety and emergency information delivery, data collection, and entertainment. The network efficiency and stability are of great concern. We devote to achieve the communication quality by appropriate gateways. The channel randomness is taken into account in the wireless network, because it...
Vehicular ad hoc network (VANET) is needful and promising to connect the 3G network. If all vehicles communicate with the 3G network directly, it will be overwhelmed. We devote to solve the problem by mobile gateways in this paper. The channel randomness can affect the stability of the communication link, which ensures reliable dissemination of information in wireless network. We analyze the communication...
In this paper, we study and compare the outage probability (OP) of a vehicular user of dual-hop moving relay node (MRN) assisted transmission, dual-hop transmission assisted by a fixed relay node (FRN), as well as of the baseline single-hop direct transmission under of co-channel interference. For an accurate comparison, we numerically optimize the FRN position which minimizes the average vehicular...
This paper presents second order statistical properties of the vehicle to vehicle Nakagami Hoyt (Nakagami-q) channel model under non-isotropic condition. The spatial-time correlation function, the power spectral density (PSD), level crossing rate (LCR) and the average fade duration (AFD) of the Nakagami Hoyt channel have been derived under the assumption that both the transmitter and receiver are...
Maximum Doppler spread or, equivalently, the vehicle velocity, can be estimated to improve handoff algorithms and tune parameters for systems when channel conditions change. This paper presents a new mobile station velocity estimator based on the normalized auto-covariance of the Rician fading signal and that of the squared envelope respectively of the received signal. The proposed algorithm is based...
Study of high speed radio wave characteristics is significant for development of High-speed mobile communication technology. According to the mobile radio propagation characteristics, a method of measurement of these characteristics is proposed in this paper. Based on the sophisticated measurement instruments and the virtual instrument technology, the high speed measurement system is established and...
Mobile terminals used in the stationary condition experience a level variation different from that found in the moving condition. Therefore, it is very important to study the fading characteristics of static usage. This paper clarifies the generalized fading characteristics of mobile terminals in outdoor NLOS environments when they are used in the stationary condition; only adjacent objects such as...
A number of Intelligent Flooding Schemes have been recently proposed in order to optimize message dissemination in Vehicular Ad Hoc Networks. In this paper we focus on a scheme which exploits a distributed timer-based contention mechanism for allowing only contention winners to forward the message and to suppress other potential forwarders. In particular, at each hop along the message propagation...
Currently, the main purpose in car-to-car networks is to improve communication performance. In order to prove this, we need a tool to evaluate statistical values such as the number of vehicles that have received the information, time of reception of the message, etc. In this study, we demonstrate how it is possible to simulate real scenarios with car-to-car technology and evaluate all traffic parameters...
Vehicle-to-infrastructure communication for accident avoidance is an important application defined in the IEEE 802.11p. The primary challenge in the current IEEE 802.11p draft standard is the weak performance of channel estimation (CE) in multipath environments due to insufficient pilot density. Therefore, we propose time-domain (TD) CE techniques that can effectively and accurately estimate channel...
This paper presents a comparative analysis, set in Vanet scenarios and based on simulations, between the well-known IEEE 802.11p standard and an efficient slotted protocol based on RR-Aloha (MS-Aloha). Notably the chosen slotted protocol is completely distributed and based on reservation, and has been specifically designed to face issues typical of mobility, while preserving quality of service guarantee...
Time selective fading investigations based on 3.5-GHz SISO narrowband envelope data are carried out in a micro-cellular propagation environment. Spatial correlation functions are calculated and compared to the theoretical Nakagami-Rice correlation function, and a good match was obtained. An alternative formulation of the autocorrelation estimator suitable not only for stationary environments is used...
In this paper, we review the state of the field on measurements, models, and analysis for the vehicle-to-vehicle (V2V) channel. We first provide a survey of existing work on V2V models, including analytical and empirical models, and note main features and findings. Remaining work to be done in V2V modeling is then described, beginning with the logical next steps, then addressing less obvious areas...
This is the following paper after the first study for inside vehicle wireless communication system design with UWB (ultrawideband) technology which was presented in ITST 2007. In this paper, it is descried why UWB technology will be good for intra vehicle wireless communications and provides more detail UWB propagation analysis. Then multipath environment model intra vehicle is created in addition...
Characterization of temporal variations in wireless channel impairments plays an important role in the design of a reliable and efficient mobile communication system. Such channels are termed as fading channels since various random phenomena in the propagation path result in fading of the received signal envelope. The exact probability density functions (pdf) and distribution functions (cdf) of a...
Video-streaming can now be offered on third-generation (3G) mobile networks. Most research efforts have focused on video download. This paper presents a detailed study of challenges faced for successfully deploying applications requiring life video upload. Both subjective and objective qualities as well as the effects of mobility are analyzed on real 3G networks. Consequently, video profiles are identified...
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