Challenges and Solutions for Cellular Based V2X Communications

This chapter describes the support for IP based multimedia services on Third Generation (3G) wireless cellular networks. While earlier cellular networks offered only basic IP connectivity on a best-effort basis, 3G networks provide explicit support for real time multimedia services with guaranteed Quality of Service (QoS). As a result, they can offer traditional voice telephony, rich telephony services and multimedia streaming over IP, both inside a 3G network and in conjunction with external networks such as the Internet, the Public Switched Telephone Network (PSTN) and the Integrated Services Digital Network (ISDN). In fact, 3G networks will deploy for the first time in a large scale technologies such as IP version 6 (IPv6) and policy based IP QoS, spearheading the introduction of such technologies into the Internet. The two most important aspects of 3G networks with respect to IP based multimedia services are the IP Multimedia Subsystem (IMS) and the Multimedia Broadcast / Multicast Service (MBMS). The IMS enables complex IP based multimedia sessions to be created with guaranteed QoS for each media component. Example applications include voice telephony and video conferencing. The IMS interoperates with both traditional telephony services and external IP based multimedia services. The MBMS provides native IP broadcast and multicast support in 3G networks, allowing high bandwidth services to be economically offered to multiple users. Example applications include video streaming via multicast and location based services via broadcast. The MBMS interoperates directly with IP multicasting. While both the IMS and the MBMS are IP based, their standardization is proceeding independently. It is however clear that their combination would allow numerous new services to be provided. The outline of this chapter is as follows. In Section II we give an overview of cellular networks and their evolution, while in Section III we describe in detail a specific 3G network, the Universal Mobile Telecommunications System (UMTS). Section IV presents an introductory description of the features and services provided by the IMS and the MBMS. In Section V we provide the details of the IMS, including service architecture, session setup and control and interworking issues. Section VI describes the MBMS in the same manner as for the IMS. Finally, Section VII discusses the QoS issues for IP based multimedia services, describing the overall QoS concept, the policy based QoS control scheme and its application to IMS sessions. At the end of the chapter, Tables II and III list the acronyms used. An extensive UMTS vocabulary is provided in [1].

Single Frequency Network(SFN) transmission mode in Long Term Evolution(LTE) can be used to deliver Multimedia Broadcast Multicast Service(MBMS) business in the form of sharing wireless resources. It has negative effect on the spectral efficiency while the allocation of resources in SFN mode refers to the worst signal user. This paper introduces a novel transmission mode named Mixture Mode(MIX) for MBMS transmission, and proposes an optimized switching mechanism denominated MIX-SFN-PTP(MSP) to dominate the switching among MIX, SFN and Point-to-point(PTP). PTP and SFN are incorporated in MIX, and a fast-select algorithm working in a greedy manner is designed to determine the ways in which users receive the MBMS business. MIX and MSP are evaluated through simulation experiments. The results show that MIX is able to obtain higher spectral efficiency compared with SFN transmission mode, and MSP can economize more wireless resources than traditional algorithm in the case that users have subpar signal.

Vehicular communications provide effective means to improve road safety and traffic efficiency, as well as high definition onboard infotainment services, capable of scaling well from current connected cars to future autonomous driving. Dedicated short-range communications (DSRC) and Long Term Evolution vehicle-to-everything (LTE-V2X) are recognized as being the two most promising technologies to support such communications. For more than a decade, DSRC has been actively promoted by ETSI, IEEE, and other standards organizations. More recently, LTEV2X is being proposed as an alternative technology based on cellular standards by 3GPP. This article analyzes the ready-to-deploy DSRC and the promising LTE-V2X, compares them according to a set of significant technical and non-technical aspects, and outlines the limitations of both technologies.

With the increasing capabilities of mobile terminals, the reception of mul-timedia content is becoming more and more attractive for customers. Im-proving high bandwidth provision enables 3G cellular systems to deliver such data to the end user. The 3G mobile experience is following a trend towards personalized services and applications which are used not only for voice communication but also for entertainment. Customers favour short video/audio clips rather than watching complete movies on their small screen. The deployment of new broadcasting networks like Digital Video Broadcasting - Handheld (DVB-H) results in large costs both in terms of capital as well as operating expenditure. Hence it is an enormous commer-cial risk for providers to install such systems. Multimedia Broadcast Multicast Service (MBMS) is considered a prom-ising technology to distribute multicast and broadcast services efficiently and at reasonable costs within existing 3GPP cellular networks. Enriched interactive multimedia services can be offered providing, for example, the latest news or publishing the current top ten music video clips. The trend towards user generated content distribution which is observed in the Inter-net will no doubt increase the number of available services and content. Set against this background of predicted increase both in terms of num-ber of services/content and users, the competition for limited resources will only intensify. MBMS is regarded as a bearer technology and not a com-plete service provisioning system therefore efficient scheduling for optimal utilization of radio and network resources is essential. Scheduling in MBMS comprises several levels of abstraction which require different strategies. This chapter presents several scheduling techniques and ap-proaches for MBMS content distribution. It explains the concepts of (1) a Dynamic MBMS Resource Scheduler located in the Radio Access Network (RAN), (2) a Carousel Service Scheduling approach and (3) means for an optimal scheduling of Multicast Streaming Services. The latter two sched-ule services and content while the first deals with IP packets.

Sophisticated Spectrum Sharing Analysis: The Case of the 5.9 GHz Band

In recent years, mobile operators are observing a growing demand of multicast services over radio cellular networks. In this scenario, multicasting is the technology exploited to serve a group of users who simultaneously request the same data content. Since multicast applications are expected to be massively exchanged over the forthcoming fifth generation (5G) systems, the third-generation partnership project (3GPP) defined the multimedia broadcast multicast service (MBMS) standard. MBMS supports multicast services over long-term evolution (LTE), and the 4G wireless technology provides high quality services in mobile environments. Nevertheless, several issues related to the management of MBMS services together with more traditional unicast services are still open. The aim of this chapter is to analyze the main challenges in supporting heterogeneous traffic over LTE with particular attention to resource management, considered as the key aspect for an effective provisioning of mobile multimedia services over cellular networks.

Multimedia Broadcast/Multicast Service (MBMS) uses point-to-multipoint transmission mode, which can effectively improve the frequency utilization efficiency of the mobile communication system and becomes a hot research field of mobile communication. However, as the frequency selectivity of the wireless channel, the throughput of the MBMS system is always limited by the user with the worst channel quality. In order to overcome the frequency selective fading, resource allocation methods is widely studied in the research. In this paper, the improved resource allocation algorithm based on user QoS is proposed. Firstly, the subcarriers are allocated according the users' urgency degree guaranteeing the QoS of all users, Secondly, the remaining subcarriers are allocated by the throughput maximization rule, Finally, the system throughput is further improved by the bit loading step with greedy algorithm. Simulation result shows that the proposed resource allocation scheme cannot effectively guarantee the QoS of all users in the group, but also can improve the system throughput as much as possible.

Various advanced methods have been proposed to achieve sufficiently high throughput as well as reliability for multimedia broadcast multicast services (MBMS) within 3GPP RAN and GERAN. One of the methods which yield promising results with only marginal system modifications is based on outer Reed-Solomon (RS) coding on the radio link control (RLC) layer. For initial studies standard decoding algorithms based on erasure-only decoders have been employed. In order to further improve the performance, the system can be viewed as a serially concatenated code such that iterative decoding can be performed. Then, advanced receivers for MBMS over GERAN would incorporate soft-in soft-cut (SISO) decoders for both the inner convolutional code, as well as the outer RS code. Whereas for the convolutional code, standard SISO algorithms are applied, for the outer RS code a standard Berlekamp-Massey algorithm is modified to accept soft-input and to provide soft-output. With this modified iterative decoding strategy, simulations have shown gains of up to 14% in throughput on typical mobile radio channels

The exploration is built upon Delphi’s, Nissan’s, Cohda Wireless’ and Savari’s experiences in Asia, Europe and U.S.A. It describes and derives lessons from all four companies’ contributions in projects such as SMARTWAY in Japan, Drive C2X and in Europe, as well as the Connected Vehicle Safety Pilot in the U.S.A. All the above programs were implemented by means of the Dedicated Short Range Communication (DSRC) technology in the SHF spectrum based on the IEEE 802.11p/Wireless Access in Vehicular Environments (WAVE) standard. The study is supplemented with insights regarding complementary technologies such DSRC in the lower UHF frequency band (i.e. 700 MHz) as well as a V2X implementation through the 4G LTE (Long Term Evolution) cellular telecommunication technology. This paper addresses issues regarding the physical layer (PHY) of the DSRC system. The combination of the delay profile caused by multipath propagation along with the motion-based Doppler spread leads to time and frequency dispersion. This limits the number of bytes acceptable for reliable communication or requires a solution at the receiver end. The analysis of the Doppler spread shows that DSRC implemented at 700 MHz is more immune from data packet length issues as opposed to 5 GHz DSRC. On the other hand, 700 MHz DSRC exhibits a much longer delay spread. Thus, guard time interval specified in ASTM E2213-03 cannot be applied as is to 700 MHz DSRC. This paper refers to the German project CoCarX and the Japanese SKY for pedestrian for studying the feasibility a V2X system built on the 4G/LTE technology and its infrastructure. It provides on a vision for an accelerated V2X deployment based on a heterogeneous system. Last, we recommend the ITS stakeholders to carry out extensive research and validation works on DSRC capacity for ensuring a large scale deployment.

One of the key objectives of Universal Mobile Telecommunications System (UMTS) is the realization of enhanced end-user experience through the provision of rich multimedia services, ensuring in parallel an economical delivery cost for service providers. Multimedia Broadcast/Multicast Services (MBMS) framework of UMTS epitomizes the increasing popularity of such applications by efficiently delivering multimedia traffic to a large number of users and optimizing the radio interface of UMTS networks. For exploiting resource efficiency, MBMS specifications consider the Counting Mechanism which decides whether it is more economic to deliver MBMS multicast traffic over point-to-point (PTP) or point-tomultipoint (PTM) bearers. However, the necessity to further improve MBMS resource efficiency and integrate new technologies such as High Speed Downlink Packet Access (HSDPA) stresses the need for an advanced Counting Mechanism. To this direction, in this paper we propose a novel Power Counting Mechanism which performs optimal power resource utilization and incorporates the HSDPA broadband extension of UMTS for enhanced performance.

In mobile networks, the provision of rich multimedia services, such as Mobile TV, is considered of key importance. To this end, Multimedia Broadcast/Multicast Service (MBMS)--that was introduced in the Release 6 of Universal Mobile Telecommunication System (UMTS)--is envisaged to play an instrumental role in the proliferation of mobile market. The reason behind the design of MBMS was the need to provide multiple users with the same data at the same time in 3GPP (3rd Generation Partnership Project) cellular networks. Still, MBMS performance is limited by the base stations' transmission power. As an aftermath, efficient power allocation techniques should be implemented so as to ensure the mass provision of multimedia applications to mobile users. This paper proposes a novel mechanism for efficient radio bearer selection during MBMS transmissions. The proposed mechanism is based on the concept of transport channels combination in any cell of the network. Furthermore, the mechanism exploits the performance enhancements emerged from Multiple Input Multiple Output (MIMO) antennas and manages to efficiently deliver multiple MBMS sessions. The proposed mechanism is thoroughly evaluated and compared with the radio bearer selection mechanisms proposed by 3GPP.

Recently 3GPP (Third Generation Partnership Project) has standardised MBMS (Multimedia Broadcast Multicast Services) enabling broadcast and multicast transmissions over GPRS (General Packet Radio Service) and UMTS (Universal Mobile Telecommunications System). Hence it makes an efficient usage of radio resources possible. 3GPP and 3GPP2 introduced the specification of IMS (IP Multimedia Subsystem) and MMD (Multimedia Domain), receptively, which both are responsible for resource, admission and charging control. It allows for cost efficient and flexible provision of enriched multimedia services over IP networks. Up to now the controlling IMS and MBMS are separated subsystems sharing no common interfaces. This paper introduces both systems and depicts ongoing standardisation activities regarding their interworking. Finally, it proposes a service provision architecture and describes required signalling flows which enable the provision of multicast streaming using the MBMS specifications not only as access bearer technology. Thus, we present a step towards the evolution of IMS enabling it with multicast and broadcast capabilities.

With the rapid development of autonomous driving technologies, it becomes difficult to reconcile the conflict between ever-increasing demands for high process rate in the intelligent automotive tasks and resource-constrained on-board processors. Fortunately, vehicular edge computing (VEC) has been proposed to meet the pressing resource demands. Due to the delay-sensitive traits of automotive tasks, only a heterogeneous vehicular network with multiple access technologies may be able to handle these demanding challenges. In this article, we propose an intelligent task offloading framework in heterogeneous vehicular networks with three Vehicle-to-Everything (V2X) communication technologies, namely Dedicated Short Range Communication (DSRC), cellular-based V2X (C-V2X) communication, and millimeter wave (mmWave) communication. Based on stochastic network calculus, this article firstly derives the delay upper bounds of different offloading technologies with certain failure probabilities. Moreover, we propose a federated Q-learning method that optimally utilizes the available resources to minimize the communication/computing budgets and the offloading failure probabilities. Simulation results indicate that our proposed algorithm can significantly outperform the existing algorithms in terms of resource cost and offloading failure probability.

To meet the growing demand for multimedia services, Multimedia Broadcast/Multicast Service (MBMS) was proposed to enhance bandwidth efficiency in wireless communication systems. Although MBMS supports multimedia streams with several resolutions, streams with different resolutions are treated as separate services and transmitted upon independent radio resources, resulting in inefficient resource utilization. At the receiver, some valuable information embedded in the higher-resolution channels is not utilized to enhance the reception of the data stream in a lower resolution channel. In this work, we propose a multilevel coupling modulation (MCM) scheme aimed to improve the overall system throughput and to extend the service coverage of the multi-resolution MBMS in orthogonal frequency division multiplexing (OFDM) systems. The proposed MCM scheme can fully utilize all the usable information conveyed in different channels, thereby improving the receiving performance. In addition, we derive the symbol error rates of the proposed MCM scheme, in the AWGN and frequency-selective fading channels, for performance evaluation. The analytical and simulation results demonstrate that the proposed MCM scheme can substantially enhance the receiving performance, service accessibility and overall system throughput of multi-resolution MBMS in OFDM systems.

The research of vehicular networks has been studied for many years. In actual life, there are a few implementations of V2X communication system, majority of them are extremely expensive. Most importantly, detailed insight implementation procedure hasn't been provided for researches. In this paper, an efficient V2X communication system based on the IEEE 802.11p/1609.X protocol stack, also known as the Wireless Access in Vehicular Environment (WAVE) standard has been designed. In this system, a Dedicated Short Range Communication (DSRC) unit using low-cost and commercial hardware which can support the vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications is developed. Some specific driver adjustments based on the IEEE 802.11a driver are taken to assure compliance with the IEEE 802.11p protocol. Besides, the development of networking layer protocol is accomplished based on IEEE 1609.3. Furthermore, three safety applications and a performance evaluation subsystem have been developed on this platform. The subsystem can test the comprehensive performance of the communication unit in terms of Packet Loss Rate (PLR), throughput and end-to-end delay. Meanwhile enormous experiments are conducted to evaluate the performance of the communication prototype and different scenarios were designed to validate the practical function of the safety applications.