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The Doppler effect is typically an impairment for wireless communications in mobile-to-mobile environments. Multipath effects leading to delay dispersion at the receiver can create a challenging doubly selective time-frequency channel response. In Vehicle-to-Vehicle (V2V) communications, small-scale effects of the V2V channel over short durations are well understood. However, observing the Doppler...
In this work, we present the fundamentals of a new sensing technique in Vehicle-to-Vehicle networks (V2V) called: Automotive Doppler Sensing (ADS), for providing road safety to connected drivers and connected autonomous vehicles by observing the Doppler profile. The Doppler profile displays the Doppler energy in the form of a high-resolution spectrogram which captures the non-line-of-sight (NLOS)...
For human-driven as well as autonomous vehicles, one of the key requirements is continuous awareness of the surroundings to detect any potential threats (vehicles, pedestrians, wild-life etc.). This requires continuous cooperation between the vehicles by efficiently sharing safety information in a timely manner. However, this is a multi-dimensional and challenging problem due to the complex nature...
Adaptive bitrate streaming is one of the most popular methods to deliver high definition video content for HTTP clients. Commonly used techniques rely primarily on the estimation of network bandwidth and/or buffer state client-side. Inaccurate estimation leads to performance degradation due to a lack of correct bitrate encoding per chunk, and poor network utilization as a result of inflexible transport...
This work presents a novel method we call: Frequency Injection Interfacing (FII), for OFDM communication systems. With FII, an external system or observer can communicate to an OFDM receiver through a frequency encoder that injects additional frequency content into the received signal. Specifically, the null subcarriers at the edges of the OFDM waveform are turned on or off to represent a binary code...
The IEEE 1609.4 standard allows a single radio device to utilize multiple channels by alternating control channel (CCH) and service channel (SCH). During the SCH interval, the RTS/CTS/data/ACK handshake can be triggered to transmit large size of data without the hidden node problem. However, it can cause the exposed node problem that hinders concurrent transmissions, which is fatal in highly dynamic...
The current IEEE 1609.4 standard defines multi-channel operations to alternate control and service channel intervals during a period of 100ms. However, there is no mention of service channel selection for a service provider, which allows hidden service providers to select the same service channel. This limitation can cause the hidden terminal problem during the service channel intervals, leading to...
Modeling large-scale fading effects in Vehicle-to-Vehicle communications (V2V) in the 5.9GHz Dedicated Short Range Communication band has received broad coverage in the literature over the last 15 years. The majority of V2V channel measurement campaigns have focused on describing the expected path loss of the V2V channel through empirical models. The path loss is a channel metric which describes how...
Vehicular Ad-hoc networks (VANETs) provide a way for a vehicle to deliver various types of information to users or drivers in other vehicles. Distributing a large amount of information such as multimedia messages in a single control channel makes the control channel easily congested. Transmitting multimedia messages through multi-channel to avoid this congestion becomes a feasible solution. However,...
The periodic broadcast of a safety message (SM) containing vehicle position and motion data is the salient mechanism for providing drivers pre-crash alerts in Vehicle-to-Vehicle (V2V) networks. However, if SMs are compromised or contain erroneous information, drivers may be unaware of impending danger. Even if vehicles were also equipped with active sensors, awareness may not be achievable in severe...
Vehicle-to-Vehicle (V2V) communication is expected to make a global impact on improving driver safety by alerting motorists of potential collisions, but the full safety benefit can only be realized if every vehicle is equipped with a transceiver. Motivated to provide collision avoidance for drivers of vehicles only equipped with a V2V transceiver, we develop a framework for using the V2V communication...
Sharing emergency messages amongst vehicles on the road can greatly reduce traffic accidents. In Vehicular Ad Hoc Networks (VANETs) to share these emergency messages, fast and reliable message dissemination is the key objective in a highly dynamic VANET environment. This research proposes a novel broadcasting protocol to achieve these goals by introducing handshake-less broadcasting, ACK Decoupling...
Vehicle-2-Vehicle safety applications using Dedicated Short Range Communication (DSRC) radios allow automobiles to exchange Basic Safety Messages (BSMs) to avoid automotive collisions. Most of these applications rely on GPS and integrated on-board sensors to obtain the position and motion information that is transmitted in a BSM. In the event that the BSM contents are compromised (i.e. hacking), providing...
Vehicular Ad Hoc Networks (VANETs) is an extension of Mobile Ad Hoc Networks (MANETs) to share traffic information and emergency alerts amongst vehicles on the road. To support many applications in VANETs, most studies use GPS to find the furthest node with ACK to ensure successful message reception. However, this ACK procedure can be removed if a channel between the sender and receiver is clear such...
A hidden-node problem is one of the major challenges that cause severe performance degradation in wireless ad-hoc networks. Even though RTS/CTS (Request To Send/Clear To Send) exchange can remove the hidden-node problem, the inefficiency of exchanging the RTS/CTS has brought attentions to many researchers. While most of these efforts have been focused on the theoretical analysis, very little efforts...
Providing tools to achieve a high level of safety transportation is the important objective in VANETs research. Hence, most of the works are devoted to developing safety-message dissemination algorithms. However, non-safety applications can also contribute to the network efficiency by exchanging traffic information. To support these applications, VANETs adopt the wireless access in the vehicular environment...
Reliability is a critical concern in disseminating safety messages in vehicular ad-hoc-networks (VANETs). Thus far, redundant broadcast (or next relay broadcast) has been used to ensure reliable transfer of safety messages. However, redundant broadcast fails to meet high-reliability requirement owing to lack of a feedback or acknowledgment (ACK) mechanism. In this work, a power controlled negative-acknowledgment...
Vehicular Ad hoc Networks (VANETs) provide vehicle-to-vehicle and vehicle-to-infrastructure communication using Dedicated Short-Range Communications (DSRC). The core objective of VANETs is to provide safety message communication among vehicles. In dense urban traffic, safety message communication encounters severe packet collisions due to excessive number of nodes contending to access the control...
Hidden nodes cause unexpected collisions and interferences in mobile ad-hoc networks (MANETs). However, little attention has been given to the behavior of hidden nodes, especially when channels are under random bit errors. Exchanging RTS/CTS can avoid hidden node problems. However, undesirable overheads in every packet cause performance degradation, and this motivates many researchers to design new...
Cognitive radio (CR) users are expected to be uncoordinated users that opportunistically seek the spectrum resource from primary users (PUs) in a competitive way. In most existing works, however, CR users are required to share the interference channel information and power strategies to conduct the game with pricing mechanisms that incur the frequent exchange of information. The requirement of significant...
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