GNSS Time Synchronization in Vehicular Ad-Hoc Networks: Benefits and Feasibility

Hasan, Khondokar Fida; Feng, Yanming; Tian, Yu-Chu

doi:10.1109/tits.2017.2789291

Cited by 71 publications

(27 citation statements)

References 46 publications

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“…Due to the simplicity, selection combining (SC) is adopted for combining signals propagating over multiple paths at the BS and UE 2 . Perfect time and frequency synchronizations, channel feedback, and CSI acquisition are supposed for the proposed SAGIN system for the analytical simplicity [22]- [26]. Further assuming a well designed transmission protocol implemented at all communication nodes, the interference among multiple transmissions in both time and frequency domains can be circumvented [27], [28].…”

Section: A System Architecturementioning

confidence: 99%

Space-Air-Ground Integrated Networks: Outage Performance Analysis

Dang

Shihada

et al. 2020

IEEE Trans. Wireless Commun.

110

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By incorporating the merits of satellite, aerial, and terrestrial communications, the space-air-ground integrated network (SAGIN) emerges in recent years as a promising solution to support seamless, high-rate, and reliable transmission with an extremely larger coverage than a classic terrestrial network. In essence, SAGIN is a cooperative relay network, in which highaltitude platforms (HAPs) and terrestrial base stations (BSs) serve as intermediates relaying signals between end device and satellite. In this paper, we thereby view the SAGIN from the perspective of cooperative communications and introduce relay networking technologies to model and construct the framework of SAGIN. Meanwhile, we take the realistic propagation environment, HAP mobility and mathematical tractability into account and reconstruct the cooperative channel models for SAGIN, including the space-air, space-ground and air-ground links. Based on the constructed framework of SAGIN, we analyze the outage performance and approximate the outage probability as well as asymptotic outage probability in closed form. Numerical results generated by computer simulations verify our analysis and provide insight into the applicability of SAGIN. Although the relaying scenarios considered in this work are simplistic, the good tractability and expandability of the constructed framework provide a solid foundation for further research of advanced systems with complex configurations.

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Section: A System Architecturementioning

confidence: 99%

Space-Air-Ground Integrated Networks: Outage Performance Analysis

Dang

Shihada

et al. 2020

IEEE Trans. Wireless Commun.

110

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“…The current time synchronization method of VANET is Global Navigation Satellite System (GNSS), which mainly includes GPS in the United States, GLONASS in Russia, GALILEO in Europe, and BEIDOU in China [19]. Since GNSS is generally unobstructed on transmission path of signal, it is easy to estimate delay of transmission [20]. In general, the more satellites that participate in time synchronization, the higher the accuracy of time synchronization.…”

Section: Related Workmentioning

confidence: 99%

An Extremely Accurate Time Synchronization Mechanism in Fog-Based Vehicular Ad-Hoc Network

Liang

2020

IEEE Access

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Fog-based Vehicular ad-hoc networks (VANETs) are new kinds of network that combine fog computing and mobile ad-hoc networks appeared in recent years, which can be used in monitoring traffic, smart driving, safe driving, and so on. Fog-based VANET is composed of a large number of dynamic nodes and static nodes, which is a heterogeneous network. Due to the heterogeneity of fog-based VANET, there is a large difference in clock rate between different nodes. It makes clock of nodes soon become inconsistent. The inaccurate clocks would lead to problems such as imprecise duty-cycle scheduling and wrong events sequence, etc. Synchronizing the clocks needs multiple message exchanges among the nodes. However, due to the mobility of the fog-based VANET, the network topology changes dynamically, which may cause synchronization packets to fail to be transmitted to a node that needs to be synchronized. In this paper, a precise time synchronization mechanism for fog-based VANET is proposed. The mechanism uses two-way message exchange method to estimate clock offset through analyzing the mobility of dynamic nodes. Clock skew is corrected using a carrier frequency offset (CFO) based hardware clock frequency estimation and considering the Doppler effect. Theoretical analyses and simulation results show that our time synchronization mechanism achieves highly accurate time synchronization. INDEX TERMS Vehicular ad-hoc networks, fog computing, time synchronization, carrier frequency offset, two-way message exchange.

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“…The GPS receiver provides the required synchronization among the vehicles. Hasan et al [23] show through real experiments that the GPS synchronization accuracy is at tens of nanoseconds which is quite acceptable for the slotted channel concept. We assume that transceiver 1 is tuned to the CCH to send and receive the periodic BSM messages, while transceiver 2 is tuned to one of the service channels.…”

Section: System Modelmentioning

confidence: 99%

A cooperative V2X MAC protocol for vehicular networks

El-Gawad

El-Sharief

Kim

2019

J Wireless Com Network

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In support of traffic safety applications, vehicular networks should offer a robust Medium Access Control (MAC) layer protocol that can provide a reliable delivery service to safety-related messages. As the safety applications generally use broadcasting to propagate their messages, a reliable broadcast protocol is essential. In general, however, broadcast is considered as unreliable by nature in contrast to unicast. This paper introduces a novel MAC protocol, called a Hybrid Cooperative MAC (HCMAC), which can substantially enhance the reliability of broadcast in vehicular networks by employing a notion of channelization. HCMAC introduces a hybrid protocol that combines a time slot allocation of Time Division Multiple Access (TDMA) and a random-access technique of Carrier Sense Multiple Access (CSMA) and thus minimizes the probability of data collisions. In addition, its feedback strategy further enhances the system performance by preventing transmissions during time slots that experience collisions. Through analysis and simulations, we compare the performance of HCMAC with VeMAC, an existing TDMA protocol. The results demonstrate that HCMAC can offer substantially faster channel access and lower collision rate compared with VeMAC.

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GNSS Time Synchronization in Vehicular Ad-Hoc Networks: Benefits and Feasibility

Cited by 71 publications

References 46 publications

Space-Air-Ground Integrated Networks: Outage Performance Analysis

Space-Air-Ground Integrated Networks: Outage Performance Analysis

An Extremely Accurate Time Synchronization Mechanism in Fog-Based Vehicular Ad-Hoc Network

A cooperative V2X MAC protocol for vehicular networks

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