Quan Yu

ChainCluster : engineering a cooperative content distribution framework for highway vehicular communications

The recent advances in wireless communication techniques have made it possible for fast-moving vehicles to download data from the roadside communications infrastructure [e.g., IEEE 802.11b Access Point (AP)], namely, Drive-thru Internet. However, due to the high mobility, harsh, and intermittent wireless channels, the data download volume of individual vehicle per drive-thru is quite limited, as observed in real-world tests. This would severely restrict the service quality of upper layer applications, such as file download and video streaming. On addressing this issue, in this paper, we propose ChainCluster, a cooperative Drive-thru Internet scheme. ChainCluster selects appropriate vehicles to form a linear cluster on the highway. The cluster members then cooperatively download the same content file, with each member retrieving one portion of the file, from the roadside infrastructure. With cluster members consecutively driving through the roadside infrastructure, the download of a single vehicle is virtually extended to that of a tandem of vehicles, which accordingly enhances the probability of successful file download significantly. With a delicate linear cluster formation scheme proposed and applied, in this paper, we first develop an analytical framework to evaluate the data volume that can be downloaded using cooperative drive-thru. Using simulations, we then verify the performance of ChainCluster and show that our analysis can match the simulations well. Finally, we show that ChainCluster can outperform the typical studied clustering schemes and provide general guidance for cooperative content distribution in highway vehicular communications.

WhiteFi Infostation: Engineering Vehicular Media Streaming With Geolocation Database

The TV white spaces (TVWS) enabled infostation has received significant attention due to its wide area coverage for cost-effective and media-rich content dissemination. In this paper, we engineer WhiteFi infostation, which is dedicated for Internet-based vehicular media streaming by leveraging geolocation database. After demonstrating the empirical observations of unique TVWS features and analyzing the real-world TVWS data collected from geolocation database, we first propose an optimal TVWS network planning to deploy WhiteFi infostation with the objective of maximizing network-wide throughput. The proposed TVWS network planning jointly considers the multi-radio configuration and the channel-power tradeoff, which can be realized by decentralized Markov approximation. Furthermore, we introduce a location-aware contention-free multi-polling access scheduling scheme for vehicular media streaming, which considered both the realistic vehicular applications and dynamics of wireless channel conditions. Through extensive simulations with real-world empirical TVWS data and urban vehicular traces, we demonstrate that our WhiteFi infostation solution can well support both the delay-sensitive and delay-tolerant vehicular media streaming services.

Spatial coordinated medium sharing: Optimal access control management in drive-thru internet

Driven by the ever-growing expectation of ubiquitous connectivity and the widespread adoption of IEEE 802.11 networks, it is not only highly demanded but also entirely possible for in-motion vehicles to establish convenient Internet access to roadside WiFi access points (APs) than ever before, which is referred to as Drive-Thru Internet. The performance of Drive-Thru Internet, however, would suffer from the high vehicle mobility, severe channel contentions, and instinct issues of the IEEE 802.11 MAC as it was originally designed for static scenarios. As an effort to address these problems, in this paper, we develop a unified analytical framework to evaluate the performance of Drive-Thru Internet, which can accommodate various vehicular traffic flow states, and to be compatible with IEEE 802.11a/b/g networks with a distributed coordination function (DCF). We first develop the mathematical analysis to evaluate the mean saturated throughput of vehicles and the transmitted data volume of a vehicle per drive-thru. We show that the throughput performance of Drive-Thru Internet can be enhanced by selecting an optimal transmission region within an APs coverage for the coordinated medium sharing of all vehicles. We then develop a spatial access control management approach accordingly, which ensures the airtime fairness for medium sharing and boosts the throughput performance of Drive-Thru Internet in a practical, efficient, and distributed manner. Simulation results show that our optimal access control management approach can efficiently work in IEEE 802.11b and 802.11g networks. The maximal transmitted data volume per drive-thru can be enhanced by 113.1% and 59.5% for IEEE 802.11b and IEEE 802.11g networks with a DCF, respectively, compared with the normal IEEE 802.11 medium access with a DCF.

Toward Multi-Radio Vehicular Data Piping for Dynamic DSRC/TVWS Spectrum Sharing

Enabling high-throughput and cost-effective vehicular communications is important for many emerging vehicular applications, such as safety applications, traffic management, and mobile Internet access. However, dedicated short-range communications (DSRC), as the sole solution so far, would meet significant challenges in the foreseeable future for supporting diverse vehicular applications simply due to the spectrum scarcity. To address this issue, in this paper, we propose an adaptive vehicular data piping framework, which is assisted by a geolocation database, for the joint utilization of DSRC and TV white space (TVWS) spectrum; in this framework, three types of vehicular data pipes (DSRC, TVWS, and cellular) are considered, while the cellular data pipe is only used as a control-plane link in coordinating the dynamic DSRC and TVWS spectrum sharing happened in the data-plane operations. In order to guarantee the optimal dynamic vehicular access to the geolocation database, we first propose a log-sum-exp (LSE) approximation-based TVWS geolocation database access approach, named LSE-WS algorithm. We formulate the adaptive vehicular data piping problem for dynamic DSRC/TVWS spectrum sharing as a coalitional formation game, and it is shown that the proposed coalitional formation approach reaches the optimal and Nash-stable vehicular data pipe selection partition in a distributed way. Through extensive simulations, we demonstrate that not only the proposed LSE-WS algorithm satisfies the dynamic vehicular geolocation database access requirement but also the adaptive multi-radio vehicular data piping approach for dynamic DSRC/TVWS spectrum sharing significantly outperforms the traditional DSRC solution.

Service-Oriented Dynamic Connection Management for Software-Defined Internet of Vehicles

Internet of vehicles (IoV) is an emerging paradigm for accommodating the requirements of future intelligent transportation systems (ITSs) with the overwhelming trend of equipping vehicles with versatile sensors and communications modules, and facilitating drivers and passengers with a variety of innovative ITS applications. However, the implementation of IoV still faces many challenges, such as flexible and efficient connections, quality of service guarantee, and multiple concurrent support requests. To this end, in this paper we introduce the software-defined IoV (SD-IoV), which is able to tackle the above-mentioned issues by adopting the software-defined networking framework. We first present the architecture of SD-IoV and develop a centralized vehicular connection management approach. Then, we aim to allocate dedicated communications resources and underlying vehicular nodes to satisfy each service. We formulate the dynamic vehicular connection as an overlay vehicular network creation (OVNC) problem. A comprehensive utility function is also designed to serve as the optimization objective of OVNC. Finally, we solve the OVNC problem by developing a graph-based genetic algorithm and a heuristic algorithm, respectively. Extensive simulation results are provided to demonstrate the effectiveness of our proposed solution of dynamic vehicular connection management.

TV White Space Enabled Connected Vehicle Networks: Challenges and Solutions

Connected vehicle technology provides many potential benefits on the road such as safety applications, effective traffic management, and mobile Internet access. In order to mitigate the resulting high spectrum demands and provide vehicular connectivity with wider communication range, higher transmission rate, and lower data transfer cost, in this article, we exploit the abundant TV white space with superior propagation characteristics and building penetration performance. We first present the application scenarios exploiting TV white space in heterogeneous connected vehicular communication networks, and discuss white space channel availability and characteristics for vehicular communications. We then propose TV white space geolocation database based vehicular communication architectures for vehicle-to-infrastructure (V2I) communications and vehicle-to-vehicle (V2V) communications. Finally, we highlight the key technical challenges and pinpoint future research directions toward exploiting TV white space for vehicular communication networks.

Conclusion and Future Research Directions

Radio spectrum scarcity has become a critical limitation for the development of new wireless equipments, applications, and services. To alleviate such burden, more and more researches have been conducted for improving the spectrum utilization efficiency. In this brief, we focused on one of the most promising technologies, i.e. CR-based dynamic spectrum sharing, from the view of engineering economics. In Chap. 1, the architecture of CR networks and the characteristics of traditional DSA were first presented. Then, the framework of market-driven spectrum sharing was illustrated. As mathematical backgrounds, Chap. 2 reviewed the fundamentals of mechanism design theory, and described some well-known existing mechanisms, such as SPSB, VCG and LOS. After that, three featured spectrum sharing mechanisms were demonstrated in detail. Specifically, a recall-based spectrum auction mechanism was studied in Chap. 3, where a single-seller spectrum sharing model with dynamic spectrum availabilities was considered. In Chap. 4, a two-stage spectrum sharing framework was modeled, in which a multi-seller recall-based spectrum sharing problem was analyzed by a first-stage combinatorial auction mechanism along with a second-stage Stackelberg pricing game. Chapter 5 introduced an online spectrum allocation mechanism, which aims to the scenarios with both PUs and SUs declaring their spectrum usage requests on the fly. In addition, theoretical analyses and numerical results were provided in all these chapters to prove the feasibility, efficiency, and superiority of all aforementioned designs.

Enabling efficient and wide-coverage vehicular content distribution over TV white spaces

Enabling efficient vehicular wireless connections with wide coverage for vehicular applications has gained significant attentions in both academia and industry. In this paper, we study the TV white spaces (WS) supportive vehicular content distribution with Geolocation database, which is referred to as WhiteFi Infostations. Taking into account both the realistic content distribution requirements for delay and throughput constraints in vehicular applications and the vehicular mobility as well, we propose a mobility-aware contention-free multi-polling access scheduling scheme to support both the deadline-driven and delay-tolerant vehicular content distribution applications. Through extensive simulations with real-world empirical TVWS data and urban vehicular traces, we demonstrate that our proposed vehicular content distribution solution can well support both the deadline-driven and delay-tolerant vehicular tailor-made services in vehicular ad hoc networks (VANET).

QoS-Driven Efficient Client Association in High-Density Software-Defined WLAN

A software-defined wireless local area network (SDWLAN) has gained significant interest recently from both the academic and industrial communities and initiated a paradigmatic reconsideration on the stereotyped management and control of current WLAN due to its flexibility and programmability. However, with the proliferation of mobile devices, efficient client association with quality of service (QoS) guarantees in the high-density SDWLAN is a very challenging issue. In this paper, we study the client association problem in the SDWLAN with new features, including centralized association, global network state awareness, seamless handoff, and flow-level association. We formulate the client association in a high-density scenario as an optimization problem aiming to minimize the interpacket delay of individual flows, based on an unsaturated and heterogeneous Markovian analytical model. Furthermore, we interpret the optimization problem as an NP-hard supermodular set function minimization problem, which is solved by two low-complexity heuristic methods, namely the greedy algorithm and the bounded local search algorithm. Through simulations, we demonstrate the effectiveness of our proposed client association solution.

Cooperative Vehicular Communications in the Drive-thru Internet

This brief presents a unified analytical framework for the evaluation of drive-thru Internet performance and accordingly proposes an optimal spatial access control management approach. A comprehensive overview and in-depth discussion of the research literature is included. It summarizes the main concepts and methods, and highlights future research directions. The brief also introduces a novel cooperative vehicular communication framework together with a delicate linear cluster formation scheme and low-delay content forwarding approach to provide a flexible and efficient vehicular content distribution in the drive-thru Internet. The presented medium access control and vehicular content distribution related research results in this brief provide useful insights for the design approach of Wi-Fi enabled vehicular communications and it motivates a new line of thinking for the performance enhancements of future vehicular networking. Advanced-level students, researchers and professionals interested in vehicular networks or coordinated network sharing will find Cooperative Vehicular Communications in the Drive-thru Internet a valuable reference.