Broadcast Solution Research Articles

Fast Message Broadcasting in Vehicular Networks: Model Analysis and Performance Evaluation

The pervasive use of technology in the urban environment requires evolved algorithms able to deliver messages across vehicular ad-hoc networks (VANETs). These networks could be exploited to run a vast plethora of applications, including critical ones such as emergency message distribution. The state-of-the-art broadcasting solutions are based on providing vehicles with different probabilities of forwarding the message in order to reduce message collisions and the number of hops to cover a certain area of interest. In this article, we examine a class of these propagation algorithms, discussing their model analysis and performance evaluation. Furthermore, we propose a possible algorithm’s extension introducing a dynamic setting of parameters according to the vehicular network’s conditions.

Cellular Terrestrial Broadcast—Physical Layer Evolution From 3GPP Release 9 to Release 16

We present the latest developments in the physical layer evolution for the transmission of Multimedia Broadcast Multicast Service (MBMS) over fifth generation (5G) cellular networks. We first provide an overview of how the MBMS physical layer has evolved during the initial releases of the Third Generation Partnership Project (3GPP) specifications and provide motivations and insights for key developments that have helped mature MBMS into a competitive broadcasting solution. We provide an overview of dedicated MBMS carriers for Multimedia Broadcast multicast service Single Frequency Network (MBSFN) transmission as well as Orthogonal Frequency Division Multiplexing (OFDM) numerologies with longer cyclic prefixes to support MBSFN transmission over large geographical areas with large distances between cooperating cell sites. Next, we describe the most recent enhancements to the MBMS physical layer, addressing advanced use cases in the recently completed release of the 3GPP specifications (Release 16). First, we describe the physical layer design for enabling MBSFN-based MBMS services for rooftop receivers with inter-site distances between cooperating cell sites as large as 125 km. In this realm, we demonstrate the need for an OFDM numerology with a 300-microsecond cyclic prefix to communicate effectively over channels with very large delay spreads. Next, we explain how support for high mobility up to 250 kmph was added to the standards by using an OFDM numerology that gracefully trades off inter-symbol interference due to large delay spreads and inter-carrier interference due to large doppler spreads to achieve better performance than existing numerologies at high speeds. Finally, we describe the enhancements that were made to the Cell Acquisition Subframe (CAS)—specifically, the introduction of larger aggregation levels for the Physical Downlink Control Channel (PDCCH) and the support of Physical Broadcast Channel (PBCH) repetitions—that significantly increase the coverage for the control and system information associated with MBMS that are carried by these subframes.

Avoiding Collisions at Any (Low) Cost: ADS-B Like Position Broadcast for UAVs

Unmanned Aerial Vehicles (UAVs), a.k.a. drones, are increasingly used for different tasks. With more drones in the sky, the risk of accidents rises, sparkling the need for conflict management solutions. Aircraft use a system called Automatic Dependent System-Broadcast (ADS-B) to continuously broadcast their position and speed but this system is not suitable for small drones because of its cost, complexity and capacity limitations. Broadband technologies such as Wi-Fi beacons are more suited for such dense scenarios, and they also offer the benefit of wide availability and low cost. The main challenges for Wi-Fi are (a) the multi-channel nature of the technology makes transmitter and receiver coordination difficult, and (b) standard chipsets are not designed for frequent broadcast transmission and reception. In this paper, we propose and analyze a multi-channel position broadcast solution that is robust against jamming and achieves a reliable location update within 125~ms. In addition, we implement the protocol on inexpensive embedded Wi-Fi modules and analyze the hardware limitations of such devices. Our conclusions are that even on the simplest Wi-Fi chipsets, our protocol can be implemented to achieve a realistic location broadcast solution that still perfectly mimics simulation and analytical results on the lab bench and still can achieve approximately 4~message/s throughput at a distance of 900~m on flying UAVs.

QoS‐aware broadcasting in VANETs based on fuzzy logic and enhanced kinetic multipoint relay

SummaryVehicular ad hoc networks (VANETs) are emergent concepts in terms of infrastructure‐less communication. The data dissemination is usually done using broadcast schemes. Data broadcast in VANETs is a challenging issue due to the high mobility vehicles and the varying density. On one hand, these vehicles have to share and disseminate the safety‐critical information, in real time, to other intended vehicles. On the other hand, the existing broadcast solutions do not succeed, till now, to fulfill VANETs requirements especially in terms of performance and QoS. In this paper, we propose a new QoS‐aware broadcast method in order to face VANETs communications challenges. We choose to adapt a concept originally devoted to mobile ad hoc networks (MANETs) and join it to other specific VANET techniques to introduce a new broadcasting protocol in the aim of optimizing QoS fulfilment. The proposed solution is fundamentally based on enhanced kinetic strategy assisted with fuzzy logic for QoS‐aware multipoint relay (MPR). The protocol efficiency is eventually tested through an experimental study and compared with existing methods. The results prove the over‐performance of the proposed solution.

Performance of Galileo-only dual-frequency absolute positioning using the fully serviceable Galileo constellation

The recent development of the Galileo space segment and the accompanying support of the International GNSS Service (IGS) allows for worldwide Galileo-only positioning. In this study, different techniques of dual-frequency absolute positioning using the fully serviceable Galileo constellation are evaluated for the first time and compared to the performance of GPS positioning. The daily static positioning based on the broadcast ephemeris using Galileo pseudoranges is significantly more accurate than the corresponding GPS solutions, obtaining the accuracy of a few decimeters. In the kinematic mode, the accuracy is better than 10 m and 20 m for the horizontal and vertical components, respectively, which is comparable to that of GPS. Precise absolute positioning using pseudorange and carrier phase Galileo observations combined with IGS Real-Time Service (RTS) or Multi-GNSS Experiment products is not yet as good as the corresponding GPS solutions. In the static mode, the root mean squared error (RMSE) between estimated and reference coordinates does not exceed 0.05 m and 0.06 m for the horizontal and vertical components, respectively. In the kinematic mode, the respective accuracies are better than 0.17 m and 0.21 m. Moreover, we show that both GPS and Galileo pseudorange solutions benefit from the RTS when compared to the broadcast solutions with the improvement in the accuracy between 10 and 59%. Remarkable results are achieved for Galileo Precise Point Positioning (PPP) solutions based on the broadcast ephemeris. In the static mode, the RMSE is 0.07 and 0.10 m for the horizontal and vertical components which is three and two times better, respectively, then the corresponding solutions based on GPS.

Streaming media live broadcast system based on MSE

In this paper, a streaming media live broadcast system is designed and initially implemented based on MSE (Media Source Extensions API). This paper selects HTTP-FLV as the server transport protocol and implements an HTML native FLV player. The streaming live broadcast solution achieved has better performance, lower power consumption and excellent user experience than the traditional Flash Player live broadcast solution.

Not All VANET Broadcasts Are the Same: Context-Aware Class Based Broadcast

A major building block of Vehicular Ad Hoc Networks (VANETs) is broadcasting: the use of wireless communication for sharing information among vehicles, or between the vehicles and infrastructure. Dozens of broadcast protocols have been developed in recent years, including protocols for 1-hop broadcasting of vehicle status information (beaconing) and for geocasting-based applications. However, most of these protocols were designed for one application and cannot co-exist, nor can one broadcast solution meet the demands of all applications. These observations motivated our effort to develop a holistic network layer for VANETs. We identify the need for making VANET broadcast context-aware, and for supporting four different classes of broadcast protocols, each with its own properties. These classes are not only able to co-exist on the same network layer, but also to complement one another’s functionality. Thus, large applications as well as more holistic Transport protocols can be designed by combining two or more broadcast classes. We discuss the specific characteristics of these classes and design candidate protocols for each class.

Recent Advances on Cellular D2D Communications

Device-to-device (D2D) communications have attracted a great deal of attention fromresearchers in recent years.[...]

An autonomic hierarchical reliable broadcast protocol for asynchronous distributed systems with failure detection

Reliable broadcast is a fundamental building block in fault-tolerant distributed systems. It consists of a basic primitive that provides agreement among processes of the system on the delivery of each broadcast message, i.e., either none or all correct processes deliver the message, despite failures of processes. In this work, we propose a reliable broadcast solution on top of VCube, assuming that the system is asynchronous. VCube is an autonomic monitoring layer that organizes processes on a hypercube-like overlay which provides several logarithmic properties even in the presence of processes failures. We consider that processes can fail by crashing, do not recover, and faults are eventually detected by all correct processes. The protocol tolerates false suspicions by sending additional messages to suspected processes but logarithmic properties of the algorithm are still kept. Experimental results show the efficiency of the proposed solution compared to an one-to-all strategy.

Emergency Broadcasting over CATV Channel using FM Subcarrier Technology

Emergency broadcasting is of importance method to alert people when disaster happens, but the development of network is slow in Chinese rural areas. So it is necessary to propose an emergency broadcasting solution for Chinese rural areas based on the available network. In this paper, a method that adopts FM subcarrier technology over CATV channel to broadcast emergency message have been proposed. In the method, emergency program is transmitted by CATV channel and emergency order is carried in FM subcarrier. As usual, to communicate emergency message to the public efficiently and effectively, a complete emergency broadcasting system should have following functions such as parallel broadcasting, compatibility, robustness, security, and so on. In the context, to satisfy above requirements, corresponding system construction, communication scheme, and message transmission protocol have been proposed as well. To verify the practicability, the solutions have been test in Chinese rural areas MiYun and gain good results.

Beamforming Tradeoffs for Initial UE Discovery in Millimeter-Wave MIMO Systems

Millimeter-wave MIMO systems have gained increasing traction towards the goal of meeting the high data-rate requirements in next-generation wireless systems. The focus of this work is on low-complexity beamforming approaches for initial UE discovery in such systems. Towards this goal, we first note the structure of the optimal beamformer with per-antenna gain and phase control and the structure of good beamformers with per-antenna phase-only control. Learning these beamforming structures in mmW systems is fraught with considerable complexities such as the need for a non-broadcast system design, the sensitivity of the beamformer approximants to small path length changes, etc. To overcome these issues, we establish a physical interpretation between these beamformer structures and the angles of departure/arrival of the dominant path(s). This physical interpretation provides a theoretical underpinning to the emerging interest on directional beamforming approaches that are less sensitive to small path length changes. While classical approaches for direction learning such as MUSIC have been well-understood, they suffer from many practical difficulties in a mmW context such as a non-broadcast system design and high computational complexity. A simpler broadcast solution for mmW systems is the adaptation of directional codebooks for beamforming at the two ends. We establish fundamental limits for the best beam broadening codebooks and propose a construction motivated by a virtual subarray architecture that is within a couple of dB of the best tradeoff curve at all useful beam broadening factors. We finally provide the received SNR loss-UE discovery latency tradeoff with the proposed constructions. Our results show that users with a reasonable link margin can be quickly discovered by the proposed design with a smooth roll-off in performance as the link margin deteriorates.

A channel state-driven ACM algorithm for mobile satellite communications

Summary The last decade has been characterized by an increasing demand of higher throughput and more reliable communication links for supporting multimedia applications. To this aim, the focus has been toward both broadband and broadcast solutions providing multimedia services to mobile users. In order to exploit such advanced services, ubiquitous and efficient mobile connections are required: satellite communications (SatCom), able to cover low density populated areas and to fill terrestrial coverage gaps, are a viable solution, as long as capacity is properly optimized. Waveform adaptation can be considered as one of the reference approaches for increasing the throughput and the reliability in wireless communication links. However, the large round trip time and user mobility in SatCom scenarios represent a serious challenge that limits the effectiveness of transmission parameters adaptation. In this paper, we focus on a novel state-driven adaptive coding and modulation approach aiming to predict the most suitable modulation and coding scheme for each communication state, based on channel state estimation and a Markov propagation model. The paper introduces the concept of state estimation decision reliability and transmission reliability. Different from other approaches, the state-driven algorithm allows to increase the system reliability by lowering the outage probability in the selected scenarios. The effectiveness of the proposed approach has been validated by resorting to numerical results after a careful parameter optimization. Copyright © 2015 John Wiley & Sons, Ltd.

Improvement on Gossip Routing Protocol using TOSSIM in Wireless Sensor Networks

Multicast routing protocols in the networks are inefficient to handle high priority traffic, network congestion, excessive processing of control information and retransmission procedures. Gossiping routing protocol is suitable and controlled form of reducing the overhead of routing protocols for forwarding a message. Gossiping protocol is characterized by each node randomly choosing to exchange information with another node. Modified Gossip has been considered as a scalable broadcast solution, considering destination node in wireless network. In this paper, we analyse Gossiping protocol and compare the performance of Gossiping and Modified Gossiping protocol, using new operating system TOSSIM, is a widely used operating system for modern wireless sensors. The protocols are simulated by TOSSIM and comparison results between the protocols are shown by different graphs

A Burst Effort Broadcasting Approach of MPEG-4 Video Transmission for Intervehicle Communication

Efficient and real-time video broadcasting helps to improve driving safety and to make traveling fun for drivers. However, it is hard to structure vehicles into permanent network topologies and schedules to broadcast video streaming real-time in intervehicle communication (IVC) in a high-mobility vehicular environment. In order to achieve this, we have designed a burst effort broadcasting (BEB) approach for IVC, which considers the challenges of high mobility and multihop broadcast, as well as the features of MPEG-4 video streams to adapt to highway scenarios. The BEB approach is distributed in real time without protocol overhead and comprises a queuing procedure and a scheduling scheme. The queuing procedure consists of the preprocess of video transmission, including the video shaping of groups of pictures and sequential reordering video frames. Based on the queuing procedure, a mobility-adaptive scheduler is applied to handle the broadcast and rebroadcast of the video stream. The concept of macroscopic broadcast is utilized to increase the broadcast performance and the video perceived quality of service (PQoS), and to reduce the number of unnecessary redundant broadcasts. As an evaluation, the real MPEG-4 video was conducted in simulation and the broadcast performance was compared with another protocol by the metrics of peak-signal-to-noise ratio (PSNR) and loss of video frames in different broadcasting scenarios. Then, the results were analyzed. The simulation proved that this approach is an efficient multihop broadcast solution that does indeed provide a realistic solution to promote a higher degree of video PQoS on highways.

Fast and Secure Multihop Broadcast Solutions for Intervehicular Communication

Intervehicular communication (IVC) is an important emerging research area that is expected to considerably contribute to traffic safety and efficiency. In this context, many possible IVC applications share the common need for fast multihop message propagation, including information such as position, direction, and speed. However, it is crucial for such a data exchange system to be resilient to security attacks. Conversely, a malicious vehicle might inject incorrect information into the intervehicle wireless links, leading to life and money losses or to any other sort of adversarial selfishness (e.g., traffic redirection for the adversarial benefit). In this paper, we analyze attacks to the state-of-the-art IVC-based safety applications. Furthermore, this analysis leads us to design a fast and secure multihop broadcast algorithm for vehicular communication, which is proved to be resilient to the aforementioned attacks.

Technological and non-technological innovations in B2B mobile services in Korea

This article examines the characteristics of business-to-business (B2B) mobile services in Korea in order to identify technological and non-technological innovations. A statistical analysis of 242 services was done to characterize B2B mobile services in Korea. Subsequently, service products were grouped into seven types based on service characteristics: mobile office/education solutions, network solutions, multimedia broadcast solutions, business analytical solutions, security and safety solutions, payment processing solutions and machine-to-machine (M2M) solutions for facility management. From a characteristics-based approach, ‘new’ service characteristics after 2009–2010 are linked with radical innovation while service characteristics prior to 2009–2010 (but have been ‘improved’) are linked with incremental innovation. A combination of ‘improved’ and ‘new’ service characteristics are linked with semi-radical innovation. Subsequently, incremental, radical and semi-radical innovations were distinguished. From the perspective of non-technological innovation, recombinative and customized innovations were identified to focus on the direct competences of service providers and users.

A broadcast solution to file delivery

This paper explains a working and proven file-based delivery system created to service both producers and television stations. It details the reasons why file-based delivery is better than traditional tape delivery for all parties, and discusses the set-up and process. The final video files sent to television stations are custom encoded for each station’s play server and include embedded closed captioning as required. This paper will be of particular interest to anyone still sending or receiving tape.

Scalable Video Broadcast Over Downlink MIMO–OFDM Systems

We propose a cross-layer design framework for efficient broadcasting scalable H.264 videos over the downlink multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing systems. The objective is to maximize the average peak signal-to-noise ratio of the received video streams by jointly optimizing video layer extraction, subcarrier allocation, modulation and coding, and transmit precoding, considering the heterogeneity of video sources and channel conditions. Specifically, to exploit the MIMO channel, we employ a codebook-based linear transmit precoding strategy with limited feedback. Given the fact that different quality layers of the video have different importance, we propose an adaptive modulation and coding scheme, where a fixed coding rate is used for each quality layer and unequal error protection is implemented for different layers. We further propose a subcarrier allocation strategy to assign transmission channels for different layers of different users' videos, to satisfy the decoding dependence constraints among the video layers and to maximize the reconstructed video quality. The proposed scalable video broadcast solution has a low complexity and low signaling overhead, which makes it suitable for practical implementations. We provide experimental results to demonstrate the effectiveness of the proposed solution, using both model-based simulations and an end-to-end software simulation testbed.

Performance Evaluation of Cellular Networks Offering TV Services

In this paper, the capacity of orthogonal frequency-division multiple-access (OFDMA) networks is evaluated when serving mobile TV traffic. To introduce the service within the network, we develop analytical cross-layer models to assess the performance of the system when carrying TV calls over unicast connections. The presented cross-layer analysis is general and can be adapted to all types of multimedia services. We then focus on a TV-specific capacity analysis, exploiting the possibility of broadcasting TV channels over point-to-multipoint (PtM) connections. This includes investigating an enhanced broadcast solution where the modulation is dynamically adapted to the radio conditions of connected TV users. The more complete broadcast solution over single-frequency networks (SFNs) is then evaluated, based on a novel physical-layer model integrating the combined signal gain from neighboring cells. We finally show how to maximize the system capacity through a secondary usage of the SFN resources by elastic traffic. The presented models are evaluated using numerical applications and further validated through network simulations.

Handling dynamics in diffusive aggregation schemes: An evaporative approach

Distributed computing in large-size dynamic networks often requires the availability at each and every node of globally aggregated information about some overall properties of the network. In this context, traditional broadcasting solutions become inadequate as the number of participating nodes increases. Therefore, aggregation schemes inspired by the physical/biological phenomenon of diffusion have been recently proposed as a simple yet effective alternative to solve the problem. However, diffusive aggregation algorithms require solutions to cope with the dynamics of the network and/or of the values being aggregated solutions, which are typically based on periodic restarts (epoch-based approaches). This paper proposes an original and autonomic solution, relying on coupling diffusive aggregation schemes with the “bio-inspired” mechanism of evaporation. While a gossip-based diffusive communication scheme is used to aggregate values over a network, gradual evaporation of values can be exploited to account for network and value dynamics without requiring periodic restarts. A comparative performance evaluation shows that the evaporative approach is able to manage the dynamism of the values and of the network structure in an effective way: in most situations it leads to more accurate aggregate estimations than epoch-based techniques.