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This letter presents two results for multiuser wireless systems employing dirty-paper coding strategies along with greedy scheduling over the broadcast multiple-input multiple-output channel. Specifically, an efficient and suboptimal downlink scheduler is proposed to approximate the maximum sum rate using equal power allocation, and it is shown to approach the maximum sum rate of optimal power allocation for a large number of users under optimal scheduling. The second result demonstrates that the average maximum sum rate can be tightly upper bounded when spatial multiplexing is maximized. [ABSTRACT FROM AUTHOR]

With the development of IoT, more and more data is offloaded from the cloud to the edge for computing, eventually forming a collaborative computing model at the edge. However, in this model, the problem of secure data transmission has not been solved. In this model, data is transmitted and forwarded in multiple messaging systems, and existing security schemes cannot achieve end-to-end security in a multi-hop, broadcast transmission model. Therefore, in this paper, we propose a new security scheme based on proxy re-encryption and broadcast encryption techniques. Moreover, the performance and security of the scheme are further enhanced by using online-offline techniques and a trusted execution environment when integrating the scheme with edge collaboration. Finally, this paper proves the security of the scheme in theory, compares the functionality of the scheme, analyzes the theoretical performance of the scheme, and finally measures the actual performance of the scheme in the edge collaboration system. [ABSTRACT FROM AUTHOR]

Broadcasting is a critical feature in V2X communication, allowing for the simultaneous dissemination of safety-critical messages to all nearby vehicles. However, the requirement for low latency in information dissemination and the need for reliable and efficient data transmission pose significant challenges to broadcasting in V2X communication systems. In this paper, we present a novel raptor-like coded broadcasting (RLCB) scheme for low-latency V2X communications. Firstly, we introduce feedback into a concatenated fountain code, and adjust its precoding and coding structure to achieve effective data deliverance under a limited number of retransmissions for low-latency transmission. Then, based on the raptor-like encoding and decoding structure, we propose a mutual exclusion-based network encoding (MENC) algorithm to enable retransmission in broadcasting scenarios. We also conduct a complexity analysis on the encoding and decoding process of our proposed scheme. Numerical results demonstrate the superior performance of our proposed scheme in reducing the packet error rate (PER) and improving spectral efficiency compared to the R10 code and hybrid automatic repeat request (HARQ) scheme. [ABSTRACT FROM AUTHOR]

Broadcasting is a communication mechanism utilized in VANET architecture that facilitates in disseminated of public information to help reduce traffic jams/congestions. The authentic and genuine nature of public information is required to be maintained to avoid broadcasting of false information causing mass panic and hysteria. Therefore, it is of utmost importance to secure the broadcasting information so that an intruder is unable to alter any information without compromising public nature of the information. In this paper, we have proposed a secure broadcasting architecture consisting of different layers stacked together in different formation according to operating modes. A real-time simulation model is developed in Python, while simulations are run on a supercomputer for the purpose of gathering results for highway environments. We compare the results of the proposed secure highway architecture with unsecure architecture. Overall, the results show delayed propagation time due to the availability of multiple information packets as well as prioritization of these information packets. However, there was no significant difference in retransmission of different information packets when compared with either different broadcasting probability or unsecure highway scenario, which indicates an effective as well as efficient, secure broadcasting architecture. [ABSTRACT FROM AUTHOR]

There is often a need to realize the design of a system that will be stable in data transmission. However, the process of modeling and structuring such a system is a process that initially requires data collection. Then, there is a need to recognize the working environment, as well as to know the problems that may appear in the broadcast. In this paper, there are provided and presented some appropriate models for data transmission based on the type of data (textual data, audio, video, etc.) in accordance with their frequency. In order to realize this system, initially several initial processes, calculations for possible obstacles, calculating the signal-noise ratio (S/N) are realized. The signal-noise ratio is explored based on some probabilistic calculations and so on. Then, in the work, the design of the system is conducted. To design this system, some advanced techniques are provided, which provide the possibility of managing and interconnecting the elements between themselves, through a multiplex system, and so on. All these processes are carried out on the basis of calculated, verified and validated values, to be adequate in the process of data transmission through a single channel, according to a certain bandwidth. Here is a characteristic is, that during this process can also be determined the data packing, the capacity of the transmitter channel; the speed of data transmission, etc. Designing this system is the ultimate stage of the completion of this project. Designing the multiplex system requires elements and other devices that have the task to create the respective module. Also, an integral part of this interconnection and data transmitter system are clock generators; to create relevant frequencies for all elements of the system, from particular elements but integrated into the general system. [ABSTRACT FROM AUTHOR]

This paper describes a channel estimation algorithm for the advanced terrestrial digital multimedia broadcasting (T-DMB) transmission system which is fully backward compatible with the conventional T-DMB standard. The advanced T-DMB has enhanced features which provide higher transmission data rate for increasing program channel capacity and better multimedia A/V service quality than the conventional T-DMB system by adopting a hierarchical modulation and scalable audio/video CODEC. To support the higher data rate transmission for the advanced T-DMB, high performance channel estimation and equalization techniques should be adopted into the advanced T-DMB receivers. In this paper, we propose a new channel estimation technique for the Advanced T-DMB to compensate channel distortion under dynamic multipath environment. [ABSTRACT FROM AUTHOR]

As a class of high-performance forward error correction codes, turbo codes, which can approach the channel capacity, could become a candidate of the coding methods in future terrestrial broadcasting (TB) systems. Among all the demands of future TB system, high throughput and low latency are two basic requirements that need to be met. Parallel turbo decoding is a very effective method to reduce the latency and improve the throughput in the decoding stage. In this paper, a parallel turbo decoder is designed and implemented in field-programmable gate array (FPGA). A reverse address generator is proposed to reduce the complexity of interleaver and also the iteration time. A practical method of modulo operation is realized in FPGA which can save computing resources compared with using division operation. The latency of parallel turbo decoder after implementation can be as low as 23.2 us at a clock rate of 250 MHz and the throughput can reach up to 6.92 Gbps. [ABSTRACT FROM PUBLISHER]

Future network architectures such as Named Data Networking (NDN) were born to change the way data can be transmitted from current host-centric network technologies to information-centric network technologies. Recently, many studies are being conducted to graft Vehicular NDN to the communication network technology of smart vehicles including connected vehicles. Explosion of data traffic due to Interest/Data packet broadcasting in Vehicular NDN environment is a very important problem to be solved in order to realize VNDN-based data communication. In this paper, the generation of data packet copies according to the increase in network size, vehicle speed, and frequency of interest packets in VNDN network is simulated and evaluated using ndnSIM, in order to show how severe the data broadcast storm phenomenon. The CDP(Copies of Data Packets) increased proportionally in the increase of network size or Interest frequency. [ABSTRACT FROM AUTHOR]

Todays, XML as a de facto standard is used to broadcast data over mobile wireless networks. In these networks, mobile clients send their XML queries over a wireless broadcast channel and recieve their desired XML data from the channel. However, downloading the whole XML data by a mobile device is a challenge since the mobile devices used by clients are small battery powered devices with limited resources. To meet this challenge, the XML data should be indexed in such a way that the desired XML data can be found easily and only such data can be downloaded instead of the whole XML data by the mobile clients. Several indexing methods are proposed to selectively access the XML data over an XML stream. However, the existing indexing methods cause an increase in the size of XML stream by including some extra information over the XML stream. In this paper, a new XML stream structure is proposed to disseminate the XML data over a broadcast channel by grouping and summarizing the structural information of XML nodes. By summarizing such information, the size of XML stream can be reduced and therefore, the latency of retrieving the desired XML data over a wirless broadcast channel can be reduced. The proposed XML stream structure also contains indexes in order to skip from the irrelevant parts over the XML stream. It therefore can reduce the energy consumption of mobile devices in downloading the results of XML queries. In addition, our proposed XML stream structure can process different types of XML queries and experimental results showed that it improves the performace of XML query processing over the XML data stream compared to the existing research works in terms of access and tuning times. [ABSTRACT FROM AUTHOR]

In this paper, the cellular system and broadcasting system use a cooperative transmission scheme. The conventional scheme is not consider the condition of a channel between a cellular base station (CBS) and a destination user. In this conventional scheme, two CBSs communicate with the user by the cooperative transmission scheme when the user is located in the cell edge. If CBS is distant from a user and the channel condition is poor, the performance of communication is degraded. The proposed scheme using the relay between CBS and the user located in the edge of CBSs improves the performance of the communication when the channel state between CBS and the user is bad. Also, space time block code and cyclic delay diversity scheme are used for the reliable transmission in the proposed scheme. The proposed scheme using the relay achieves good BER and throughput performance. Through the simulation, it is confirmed that the proposed scheme is better than the conventional scheme. [ABSTRACT FROM AUTHOR]

The large-scale VANET implies the network which covers a wide range of geographic space and contains a huge number of vehicles in urban scenario. The performance of traditional data transmitting protocols will be sharply decreased in such networks. In this paper, we propose a new data transmitting scheme based on improved AODV and RSU-assisted forwarding. On the premise that a certain number of RSUs are deployed in the network, the coverage area which has the highest average connectivity of each RSU is recognized using the improved watershed algorithm. The proposed data transmitting scheme includes three parts: source vehicle to RSU (SV2R), RSU to RSU (R2R) and RSU to destination vehicle (R2DV). The SV2R and R2DV are achieved using the improved AODV protocol based on restricted broadcasting. The R2R is achieved by backbone network. Simulation results show that, compared with the AODV protocol, the proposed method can significantly improve the performance in packet delivery fraction and overhead. [ABSTRACT FROM AUTHOR]

This paper aims to improve the throughput of a broadcasting system that supports the transmission of multiple services with differentiated minimum signal-to-noise ratios (SNRs) required for successful receptions simultaneously. We propose a novel multiplexing method called bit division multiplexing (BDM), which outperforms the conventional time division multiplexing (TDM) counterpart by extending the multiplexing from symbol level to bit level. Benefiting from multiple error protection levels of bits within each high-order constellation symbol, BDM can provide so-called nonlinear allocation of the channel resources. Both average mutual information (AMI) analysis and simulation results demonstrate that, compared with TDM, BDM can significantly improve the overall transmission rate of multiple services subject to the differentiated minimum SNRs required for successful receptions, or decrease the minimum SNRs required for successful receptions subject to the transmission rate requirements of multiple services. [ABSTRACT FROM AUTHOR]

Long Term Evolution (LTE) standard enhances Multimedia Broadcast Multicast Services (MBMS) to provide highly efficient transmission of multicast/broadcast services. This paper aims at clarifying which is the best option for the Enhanced MBMS (E-MBMS) network configuration according to the operator needs. Besides, it describes the main technical features of the new E-MBMS LTE standard, for both streaming and file delivery, and derives optimum operation modes. Some relevant conclusions are drawn from a set of simulation results calibrated with International Telecommunication Union Radiocommunication (ITU-R) guidelines. Regarding streaming delivery, results show that increasing the MBMS over a Single Frequency Network (MBSFN) area size allows employing a higher modulation and coding scheme level, which entails more streaming channels per MBSFN area. Concerning file delivery, results show that the reduction in the mean throughput of unicast users matches exactly the percentage of stolen subframes. Besides, the hybrid approach suggested in this paper improves the file delivery efficiency while eliminating the dependency on a MBMS threshold. [ABSTRACT FROM PUBLISHER]

In wireless broadcast system, where feedback is limited and channel state information is only available at the receiver side, layered broadcasting approach has been proposed to fully utilize the channel resources by providing different levels of service quality to users with different channel conditions. However, no upper bound has been given yet to show how the layered broadcast scheme will outperform the conventional broadcast (CB) scheme. In this paper, system average achievable rate (SAAR) is defined as the mean achievable rate of all users within the coverage. Based on continuum superposition coding (SC) with infinite layers, the upper bound of the SAAR of layered broadcasting is given by the derivation of the optimal power distribution function among the superposed layers. The results show that, by promoting the experience of stronger users (users with better channel conditions) without seriously degrading the performance of weaker users (users with worse channel conditions), layered broadcasting approach greatly increases the average system performance. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The problem of optimizing access and bandwidth sharing among Transmission Control Protocol (TCP) connections in the mobile digital video broadcasting return channel via satellite (DVB-RCS) is tackled in this paper. After sketching the general system architecture, we explicitly deal with the dynamic assignment of bandwidth to TCP connections on the return link, which is accomplished by a network control center (NCC) placed onboard the satellite. Mobile users access the satellite in multifrequency time-division multiple access (MF-TDMA), whereas they receive data from the NCC in time-division multiplexing (TDM). Two different techniques, based on deterministic and random access, are compared in terms of bandwidth usage and average completion time per connection, when the mobile user acts as both server and client. In the server case, to increase the TCP throughput, both packet-level forward error correction (FEC) on data sent by mobile users and a duplicated and delayed acknowledgment technique for TCP acknowledgment traffic from the NCC to the mobile users are applied. An analysis of the packet losses and a simulation campaign of file transfers by employing a realistic channel model has been carried out. The results of the analysis show the convenience of adopting a technique, in addition to the optimal data redundancy in different cases, such as the server or client role of users, their willingness to pay, the file size, and the environment type. [ABSTRACT FROM AUTHOR]

This paper proposes an architecture for using multiple-input multiple-output techniques for a multimode fiber broadcast channel, allowing simultaneous transmission of unique streams to different users on the same fiber while using square-last detection. The resulting system throughput scales nearly linearly with the number of transmitters and receivers. The paper also proposes a training scheme appropriate for use with square-law detection. [ABSTRACT FROM AUTHOR]

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The requirements for future DVB-TIH networks demand that broadcasters design and deploy networks that provide ubiquitous reception in challenging indoors and other obstructed situations. It is essential that such networks are designed cost-effectively and with minimized environmental impact. The EC funded project PLUTO has since its start in 2006 explored the use of diversity to improve coverage in these difficult situations. The purpose of this paper is to investigate the performance of Transmit Delay Diversity (DD) with two antennas to improve the reception of DVB-TIH systems operating in different realistic propagation conditions through a series of tests using a SPIRENT SR5500 dual channel emulator. The relationship between correlation coefficient between channels, receiver velocity and diversity gain is investigated. It is shown that transmit delay diversity significantly improves the quality of reception particularly in simulated fast fading mobile broadcasting applications. This paper documents research conducted by Brunel University and Broadreach Systems. [ABSTRACT FROM AUTHOR]

In this paper, an efficient design of dual mode deinterleaver for both IEEE 802.16 and digital video broadcasting (DVB) standards is presented. The paper first proposes a systematic data allocation method for the design of matrix transposer which can be used to realize the block deinterleaver adopted by IEEE 802.16 based on the multi- bank memory architecture. In addition, multiple input/output data can be grouped together in order to further reduce the memory access frequency such that the required number of banks and ports for the memory can be both reduced. Similarly, the multi-bank memory design approach can also be applied for the byte-level convolutional deinterleaver adopted in DVB system by realizing the multiple delay branches as the circular buffer. Finally, these two different deinterleaving standards can be further integrated . into a single design suitable for those dual-mode communication systems. Our implementation results show that the dual mode deinterleaver can run up to 150 Mhz, and consume about 38.5k gates. The same design methodology can also be applied for the design of interleavers. [ABSTRACT FROM AUTHOR]

The objective of this work is to research and analyse the performance of Cyclic Delay Diversity (CDD) with two transmit antenna on DVB-H systems operating in spatially correlated channel. It is shown in this paper that CDD can achieve desirable transmit diversity gain over uncorrelated channel with or without receiver diversity. However, in reality, the respective signal paths between spatially separated antennas and the mobile receiver is likely to be correlated because of insufficient antenna separation at the transmitter and the lack of scattering effect of the channel. Under this spatially correlated channel, it is apparent that CDD cannot achieve the same diversity gain as obtained under the uncorrelated channel. In this paper, a new upper bound on the pairwise error probability (PEP) of the CDD with spatial correlation of two transmit antennas is derived. The upper bound is used to study the CDD theoretical error performance and diversity gain losses over a generalized spatially correlated Rayleigh channel. This theoretical analysis is validated by the simulation of DVB-H systems with two transmit antennas and the CDD scheme. Both the theoretical and simulated results give the valuable insight that the CDD ability to perform well with a certain amount of channel correlation. [ABSTRACT FROM AUTHOR]

This paper considers the potential for an HDTV delivery format with 1920 x 1080 pixels progressive scanning and 50 frames per second in broadcast applications. The paper discusses the difficulties in characterizing the display to be assumed for reception. It elaborates on the required bit rate of the 1080p/50 format when critical content is coded in MPEG-4 H.264 AVC Part 10 and subjectively viewed on a large, flat panel display with 1920 x 1080 pixel resolution. The paper describes the initial subjective quality evaluations that have been made in these conditions. The results of these initial tests suggest that the required bit-rate for a 1080p/50 HDTV signal in emission could be kept equal or lower than that of 2nd generation HDTV formats, to achieve equal or better image quality. [ABSTRACT FROM AUTHOR]

Broadcasting is a prospective approach to support near video-on-demand services with light communication overhead. By letting clients share channels, such approaches involve partitioning a video into segments and repeatedly broadcasting these segments in multiple channels. An early paper proposed a broadcasting scheme called RFS (recursive frequency splitting), which can significantly reduce clients' waiting time. While efficient, RFS suffers from a high computational complexity of O(n log n), where n is the number of segments of the video, which is typically very large. This paper proposes an efficient segmentation scheme, which can significantly reduce the computational overhead by slightly sacrificing the number of segments that can be arranged as compared to RFS. [ABSTRACT FROM AUTHOR]

In practical unlicensed communications in TV band, radio devices have to identify, at first, the transmission opportunities, that is, the portion of the spectrum licensed for broadcasting services unoccupied in a certain region at certain time, that is, the so-called TV white space. In this paper the outcome of field measurements in the UHF TV band (470–860 MHz) conducted in EU is presented. To obtain empirical values for the parameters upon which unlicensed radio devices are able to distinguish in a real scenario between empty and occupied TV channels, signal power measurements have been performed in Italy, Spain, and Romania on rural, suburban, and urban sites, at different heights over the ground by using different analysis bandwidths. The aim of this work is to provide a set of practical parameters upon which harmless unlicensed communication in the UHF TV white space is feasible. The results have been analyzed with respect to the hidden node margin problem, spectrum sensing bandwidth, and occupancy threshold. [ABSTRACT FROM AUTHOR]

Wireless Data Broadcasting is a newly developed data dissemination method for spreading public information to a tremendous number of mobile subscribers. Access Latency and Tuning Time are two main criteria to evaluate the performance of such system. With the help of indexing technology, clients can reduce tuning time significantly by searching indices first and turning to doze mode during waiting period. Different indexing schemes perform differently, so we can hardly compare the efficiency of different indexing schemes. In this paper, we redesigned several most popular indexing schemes for data broadcasting systems, i.e., distributed index, exponential index, hash table, and Huffman tree index. We created a unified communication model and constructed a novel evaluation strategy by using the probability theory to formulate the performance of each scheme theoretically and then conducted simulations to compare their performance by numerical experiments. This is the first work to provide scalable communication environment and accurate evaluation strategies. Our communication model can easily be modified to meet specific requirements. Our comparison model can be used by the service providers to evaluate other indexing schemes to choose the best one for their systems. [ABSTRACT FROM AUTHOR]

The DVB standard does not mandate the use of authentication and integrity protection for transport streams. This allows malicious third parties to replace legitimate broadcasts by overpowering terrestrial transmissions. The rogue signal can then deliver a malicious broadcast stream to exploit security vulnerabilities on Smart TVs (STVs) in range. We implemented a proof-of-concept attack based on a malicious Hybrid Broadcast Broadband TV app, able to acquire permanent system-level access to an STV over the air, in less than 10 s. These attacks, however, are severely limited in range due to required co-channel protection ratios (CCPRs), which is in direct contradiction to previous publications. We present evidence for these limitations in form of laboratory experiments, extensive simulations, and field measurements. To this end, we developed an automated, low-cost method for CCPR determination, as well as a method for non-disruptive attack range measurements based on a gap filler and the resulting channel impulse response. [ABSTRACT FROM PUBLISHER]

Due to the high demands of data communication, the broadcasting system streams the data daily. This service not only sends out the message to the correct participant but also respects the security of the identity user. In addition, when delivered, all the information must be protected for the party who employs the broadcasting service. Currently, Attribute-Based Broadcast Encryption (ABBE) is useful to apply for the broadcasting service. (ABBE) is a combination of Attribute-Based Encryption (ABE) and Broadcast Encryption (BE), which allows a broadcaster (or encrypter) to broadcast an encrypted message, including a predefined user set and specified access policy to install the authorization mechanism. It is desirable to hide all the information when producing in the ciphertext, which has not been considered in the previous works of ABBE. Motivated by the above issue, we devise a solution to achieve anonymity for the ABBE scheme, which not only hides the access structures but also anonymizes the user's identity. In this work, we propose two schemes as Anonymous Key Policy (AKP)-ABBE and Anonymous Ciphertext Policy (ACP)-ABBE with supporting multiple access structures by using OR / AND gates. Specifically, we present the generic constructions of AKP/ACP-ABBE on the building block of the Inner Product Encryption (IPE ), which enables the hidden user's identity and complex OR / AND -Gate access structure. We show that our proposed schemes are secured under the standard models. [ABSTRACT FROM AUTHOR]

Mobile Ad hoc networks perform multi-hop communication in an environment without a dedicated fixed infrastructure, with mobile nodes and changing network topology. Path finding processes in on-demand route discovery methods in mobile ad hoc networks (MANETs) use flooding. Source mobile node simply broadcast route request (RREQ) packet to its neighbor node and once again the neighbor node rebroadcast RREQ to its neighbor until unless route to a particular destination is found. This can potentially lead to high channel contention, causing redundant retransmissions and thus excessive packet collisions in the network. In this paper we propose a new probabilistic method that can significantly reduce the number of RREQ packets transmitted during route discovery operation. Our simulation analysis reveals that equipping AODV with an appropriate probabilistic route discovery method can result in significant performance improvements in terms of routing overhead, MAC collisions and end-to-end delay while still achieving a good throughput when compared with the traditional AODV [1]. [ABSTRACT FROM AUTHOR]

Wireless mesh networks (WMNs) is an emerging communication paradigm to enable resilient, cost-efficient and reliable services for the future-generation wireless networks. In this paper, we study the broadcasting (one-to-all communication) in WMNs with known topology, i.e. where for each primitive the schedule of transmissions is pre-computed based on full knowledge about the size and the topology of the network. We show that broadcasting can complete in D + O(log n) time units in the WMN with size n and diameter D. Moreover, we also propose an optimal O( D)-time deterministic energy efficient broadcasting scheduling, under which each node in the WMN is only allowed to transmit at most once. Furthermore, we explore the fault-tolerant broadcasting in the WMN. We show an O( n)-time deterministic broadcasting schedule with large number of link failures. This is an optimal schedule in the sense that there exists a network topology in which the broadcasting cannot complete in less than Ω( n) units of time. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper proposes a generalized sequential slotted amplify and forward (GSSAF) strategy for single-antenna wireless cooperative networks. The diversity and multiplexing tradeoff (DMT) is analyzed. Applications to cooperative multiple relay channels, cooperative broadcast channels (CBC) and cooperative multiple access channels are considered and the DMT upper bound is proven to be achievable for each case. Other than proposing the best known near-optimal strategy for CBC, another important contribution is to show that GSSAF can be used as a unified strategy to achieve DMT optimality in wireless cooperative networks with unit multiplexing gains. [ABSTRACT FROM AUTHOR]

As we know, the data transmission in the wireless networks is more unreliable than it is in the wired network environment. Although the virtual carrier sensing scheme can be used in the wireless unicast transmission, the multicast and broadcast still not utilize the acknowledgement mechanism for reliable transmission. This is due to the acknowledgement packets of broadcast transmission will cause much higher communication traffic and overhead. Since reliable data broadcast is critical and required in many applications in the wireless sensor networks, our study focuses on the ZigBee network which is a new industrial standard for sensor networks. Some previous related papers improved the broadcast reliability by introducing redundant transmission and increasing coverage ratio of every receiver node, but there still exists probability of packet loss and extra communication cost due to redundant broadcast. This paper proposes an efficient acknowledgement-based approach for reliable data broadcast in wireless sensor networks. Hierarchical acknowledgement mechanism, reduction of rebroadcast packets and ACK packets, degree-based ACK/rebroadcast Jitter, and parent-oriented retransmission are the key schemes to achieve the efficient data broadcast. Simulation results show that the proposed schemes can efficiently reduce the acknowledgement traffic as well as communication overhead and provide the high reliable data broadcast transmission in ZigBee networks. [ABSTRACT FROM AUTHOR]

Underwater acoustic networks have recently emerged as a new area of research in wireless networking. These networks can support a large number of applications such as environmental and underwater equipment monitoring. In recent years, there has been substantial work on protocol design for these networks with most efforts focusing on MAC and network layer protocols. Despite being a fundamental networking primitive, data broadcasting has so far received little attention in the context of underwater networks. This paper proposes an adaptive push system for dissemination of data in underwater acoustic wireless networks. Besides achieving adaptation of its broadcast schedule according to the a priori unknown needs of the clients, the proposed system also efficiently combats the problem of high latency of the underwater acoustic wireless environment. Simulation results show superior performance of the proposed system in the underwater environment compared to adaptations of existing terrestrial push systems. [ABSTRACT FROM AUTHOR]

Broadcast is a fundamental operation of wireless ad hoc networks (WANETs) and has widely been studied over the past few decades. However, most existing broadcasting strategies assume nonsleeping wireless nodes and thus are not suitable for uncoordinated duty-cycled WANETs, in which each node periodically switches on and off to save energy. In this paper, we study the minimum-transmission broadcast problem in uncoordinated duty-cycled WANETs (MTB-UD problem) and prove its NP-hardness. We show that modifications of existing broadcast approaches can only provide a linear approximation ratio of O(n) (where n is the number of nodes in the network). We propose a novel set-cover-based approximation (SCA) scheme with both centralized and distributed approximation algorithms. The centralized SCA (CSCA) algorithm has a logarithmic approximation ratio of 3(ln Δ + 1) and time complexity of O(n3) (Δ is the maximum degree of the network). The distributed SCA (DSCA) algorithm has a constant approximation ratio of at most 20 while keeping both linear time and message complexities. We have conducted both theoretical analysis and simulations to evaluate the performance of the proposed algorithms. Results show that both the CSCA and DSCA algorithms outperform the modified versions of existing broadcast approaches by at least 50%. [ABSTRACT FROM AUTHOR]

This paper presents the design of an advanced terrestrial digital multimedia broadcasting (AT-DMB) baseband receiver SoC. The AT-DMB baseband is incorporated into a hierarchical modulation scheme consisting of high priority (HP) and low priority (LP) stream decoders. The advantages of the hierarchical modulation scheme are backward compatibility and an enhanced data rate. The structure of the HP stream is the same as that of the conventional T-DMB system; therefore, a conventional T-DMB service is possible by decoding multimedia data in an HP stream. An enhanced data rate can be achieved by using both HP and LP streams. In this paper, we also discuss a time deinterleaver that can deinterleave data for a time duration of 384 ms or 768 ms. The interleaving time duration is chosen using the LP symbol mapping scheme. Furthermore, instead of a Viterbi decoder, a turbo decoder is adopted as an inner error correction system to mitigate the performance degradation due to a smaller symbol distance in a hierarchically modulated LP symbol. The AT-DMB baseband receiver SoC is fabricated using 0.13 μm technology and shows successful operation with a 50 mW power dissipation. [ABSTRACT FROM AUTHOR]

Data broadcasting is an efficient way of delivering information over asymmetric wireless environments, and push systems can provide high scalability and client hardware simplicity. Many environments, however, are characterized by a priori unknown client demands and groups of clients that are located at the same region and have similar demands. The main disadvantage of the approaches in such cases is the lack of fairness, because groups with few members have much lower performance than groups with many clients, because the performance per group (directly) depends on the group size. In this paper, we propose a fair push system where the performance of each client is independent of the total number of clients that are located in the same region. This condition is achieved without the overall performance of the system being significantly affected. Moreover, the proposed fair system is extended to a priority-based system that multiplies the performance of a specific group, depending exclusively on its priority level in relevance to the rest of the groups. [ABSTRACT FROM AUTHOR]

Digital Video Broadcasting via Satellite-Second Generation (DVB-S2) was originally designed for fixed terminals, but it has recently been adopted by the DVB Return Channel via Satellite for Mobile scenario (DVB-RCS+M) under the singlecarrier-per-channel (SCPC) mode. For the purpose of adapting DVB-S2 for mobile reception, it has been agreed that, among others, forward error correction (FEC) at the link layer (LL) is a suitable means of achieving reliable reception in mobile environments. Prime candidates for LL-FEC had already been available schemes in the DVB family of standards: multiple-protocol encapsulation-FEC (MPE-FEC) and MPE interburst FEC (MPE-IFEC). Furthermore, different FEC codes may be applied within these schemes, i.e., Reed-Solomon (RS) or Raptor FEC codes. This paper introduces the integration of such schemes and codes on top of DVB-S2. In addition, we analyze the performance that can be achieved when applying these schemes with particular focus on two typical railway scenarios: 1) line of sight, together with the effect of railway power arches (LOS+PA), and 2) nonline of sight (nLOS). Both theoretical and simulation analyses reveal that LL-FEC can overcome typical fading effects in the railway scenario by selecting appropriate FEC codes and optimizing the coding parameters. We show that MPE-IFEC and extended MPE-FEC with Raptor codes - as finally specified in DVB-RCS+M-consistently show superior results over those of other LL-FEC for railway scenarios. We also indicate signaling updates to allow achievable performance. As for practical implementation, we propose two possible novel cross-layer architectures for unicast DVB-52 to provide quality of service (QoS). The architectures allow the migration from traditional packet encapsulation based on Moving Picture Experts Group 2-Transport Streams (MPEG2-TS) to new schemes, such as generic stream encapsulation (GSE). [ABSTRACT FROM AUTHOR]

Due to the recent popularization of digital broadcasting systems, selective contents, i.e., watching contents selected by users themselves, have attracted great attention. For example, in a news program, after a user selects an interesting content, he/she watches it. In selective contents broadcasting, since the server needs to deliver many contents, the necessary bandwidth for continuously playing the data increases. Conventional schemes reduce the necessary bandwidth by producing an effective broadcast schedule. However, they do not consider the upper limit in the bandwidth. When an upper limit exists in the bandwidth, users may wait to play the data. In this paper, we propose a broadcasting scheme that reduces waiting time by considering available bandwidth. In our proposed scheme, by acquiring the channel bandwidth that is the same as the data consumption rate, we effectively reduce the waiting time. [ABSTRACT FROM AUTHOR]

LDPC codes are state-of-art error correcting codes, included in several standards for broadcast transmissions. Iterative soft-decision decoding algorithms for LDPC codes reach excellent error correction capability; their performance, however, is strongly affected by finite-precision issues in the representation of inner variables. Great attention has been paid, in recent literature, to the topic of quantization for LDPC decoders, but mostly focusing on binary modulations and analysing finite precision effects in a disaggregrated manner, i.e., considering separately each block of the receiver. Modern telecommunication standards, instead, often adopt high order modulation schemes, e.g. M-QAM, with the aim to achieve large spectral efficiency. This puts additional quantization problems, that have been poorly debated in previous literature. This paper discusses the choice of suitable quantization characteristics for both the decoder messages and the received samples in LDPC-coded systems using M-QAM schemes. The analysis involves also the demapper block, that provides initial likelihood values for the decoder, by relating its quantization strategy with that of the decoder. A new demapper version, based on approximate expressions, is also presented, that introduces a slight deviation from the ideal case but yields a low complexity hardware implementation. [ABSTRACT FROM AUTHOR]

In this paper we analyze the performance of a low complexity superimposed channel estimation technique for orthogonal frequency division multiplexing (OFDM). In particular, an analytical model of interference due to channel estimation errors and imperfect superimposed sequence cancellation at receiver is proposed, whose effectiveness is validated by simulations. Indeed, the significative length of OFDM symbols used in new wide area broadcasting applications makes the superimposed technique a viable alternative to the classical pilot aided technique. For the same computational complexity, the comparison between the two techniques is based on the achievable system throughput both for the current terrestrial digital video broadcasting (DVB-T) standard and for the proposed next generation DVB-T (DVB-T2). Our results show that superimposed technique provides higher bit-rates than the pilot aided technique, with a gain in the range of 4% to 10%. [ABSTRACT FROM AUTHOR]

Histogram equalization is a simple and effective method for contrast enhancement as it can automatically define the intensity transformation function based on statistical characteristics of the image. However, it tends to alter the brightness of the entire image, which it is not suitable for consumer electronic products, where preservation of the original brightness is essential to avoid annoying artifacts. This paper presents a new contrast enhancement method for generalization of the existing bihistogram equalization (BHE) and recursive mean-separate histogram equalization (RMSHE) methods. The proposed method is referred to gain-controllable clipped histogram equalization (GC-CHE) to provide both histogram equalization and brightness preservation. More specifically adaptive contrast enhancement is realized by using clipped histogram equalization with controllable gain. The clipping rate is determined based on the mean brightness, and the clipping threshold is determined based on the clipping rate. The clipping rate is adaptively controlled to enhance the contrast with preserving the mean brightness. It is mathematically proven that the mean brightness of the output image converges to that of the input image with adaptive controlled. Simulation results show that the proposed GC-CHE method outperforms existing histogram-based methods, such as HE, BHE, and RMSHE, in various situations. [ABSTRACT FROM AUTHOR]

This paper proposes an efficient parallel algorithm for computing Lagrange interpolation on k-ary n-cube networks. This is done using the fact that a k-ary n-cube can be decomposed into n link-disjoint Hamiltonian cycles. Using these n link-disjoint cycles, we interpolate Lagrange polynomial using full bandwidth of the employed network. Communication in the main phase of the algorithm is based on an all-to-all broadcast algorithm on the n link-disjoint Hamiltonian cycles exploiting all network channels, and thus, resulting in high-efficiency in using network resources. A performance evaluation of the proposed algorithm reveals an optimum speedup for a typical range of system parameters used in current state-of-the-art implementations. [ABSTRACT FROM AUTHOR]

In this paper, we consider a peer-to-peer (P2P) network, where multimedia streams are broadcast by matched peers based on their resource reciprocation profiles. We propose a new framework where each peer creates a coalition of matched peers with which it can exchange resources in order to improve its utility. The utility is determined based on explicit consideration of the peer's multimedia attributes and the quality derived by the peers' reciprocation behavior. We adopt the proportional bargaining solution to negotiate the upload bandwidth among the matched peers. Proportional bargaining allows to determine each peer's optimal (in a Pareto optimal sense) upload rates in a coalition in terms of its utility impact. The impact of an incoming peer on the coalition value, which represents the collective utility achieved by the peers in a coalition, is assessed by explicitly investigating the coalition value improvement. Finally, our results show that the proposed coalition-based resource reciprocation can improve the resource allocation/scheduling algorithms deployed in existing P2P systems such as BitTorrent and CoolStreaming. We also discuss how the proposed resource reciprocation approach can be implemented in other multimedia broadcasting applications. [ABSTRACT FROM AUTHOR]

Scheduling in a Broadcast (BC) channel based on partial Channel State Information at the Transmitter (CSIT)is carried out in an opportunistic way, where several orthogonal beams are randomly generated at the Base Station transmitter to simultaneously deliver several users with their intended data. The paper presents a power allocation over the transmitting beams, where a minimum rate per user restriction is required for each scheduled user, standing as a potential Quality of Service (QoS) indicator for the system behaviour. However, in practical wireless scenarios the CSIT is imperfect due to non-accurate estimation, so that robust schemes are required to meet the system demands. Based on the allowed system outage in the QoS achievement, different robust power allocation schemes are proposed, which are efficiently solved through convex optimization tools. The presented strategies are later compared via simulations for the different scenarios and the system specifications. [ABSTRACT FROM AUTHOR]

In a multiple-antenna system with two transmitters and two receivers, a scenario of data communication, known as the X channel, is studied in which each receiver receives data from both transmitters. In this scenario, it is assumed that each transmitter is unaware of the other transmitter's data (noncooperative scenario). This system can be considered as a combination of two broadcast channels (from the transmitters' points of view) and two multiple-access channels (from the receivers' points of view). Taking advantage of both perspectives, two signaling schemes for such a scenario are developed. In these schemes, some linear filters are employed at the transmitters and at the receivers which decompose the system into either two noninterfering multiple-antenna broadcast subchannels or two noninterfering multiple-antenna multiple. access subchannels. The main objective in the design of the filters is to exploit the structure of the channel matrices to achieve the highest multiplexing gain (MG). It is shown that the proposed noncooperative signaling schemes outperform other known noncooperative schemes in terms of the achievable MG. In particular, it is shown that in some specific cases, the achieved MG is the same as the MG of the system if full cooperation is provided either between the transmitters or between the receivers. In the second part of the paper, it is shown that by using mixed design schemes, rather than decomposition schemes, and taking the statistical properties of the interference terms into account, the power offset of the system can be improved. The power offset represents the horizontal shift in the curve of the sum-rate versus the total power in decibels. [ABSTRACT FROM AUTHOR]

Current satellite digital broadcasting transmission system "ISDB-S " employs digital modulation schemes, BPSK, QPSK, and 8PSK combined with a concatenated code consists of convolution code and Reed- Solomon code. While, in recent years, transmission systems adopted LDPC codes have been developed. Multi-level digital modulation schemes combined with LDPC codes can achieve more efficient transmission. In this paper, we propose a new transmission system employed LDPC, multi-level modulation and advanced TMCC signal. [ABSTRACT FROM AUTHOR]

Due to the recent popularization of mobile multi- media broadcasting, broadcasting continuous media data such as audio and video has attracted great deal of attention. In general continuous media data broadcasting, since clients have to wait to receive data before playing it, various schemes to reduce waiting time have been studied. Some reduce the waiting time by dividing the data into several segments and broadcasting preceding segments frequently with a single channel. However, by dividing the data into numerous segments and producing an effective broadcast schedule, the waiting time can be further reduced. In this paper, we propose a scheduling protocol to reduce waiting time with large-scale data segmentation. [ABSTRACT FROM AUTHOR]

In this paper, we develop optimization techniques for linear zero-forcing (ZF) multiple-input, multiple-output (MIMO) broadcast (BC) precoders. A computationally efficient technique based on QR-update algorithms for implementing this optimization is then proposed. The application of the proposed ZF precoders and decoders to systems with both large and small numbers of users is considered. The proposed optimization technique is also shown to perform very well in conjunction with nonlinear Tomlinson- Harashima precoding. Both coded and uncoded performances are considered. [ABSTRACT FROM AUTHOR]

Necessary and sufficient conditions for Logd(N, m, p) network to be point-to-point strictly nonblocking are known. Recently, Kabacinski and Danilewicz obtained necessary and sufficient conditions for the Log2 (N, 0, p) network to be broadcast strictly nonblocking. In this paper, we give necessary and sufficient conditions for Logd(N, m, p) to be f-cast strictly nonblocking for every f, thus covering the point-to-point case (f = 1) and the broadcast case (f = N) as special cases. [ABSTRACT FROM AUTHOR]

In this paper we address the emerging application of mobility to DVB-S2/DVB-RCS systems, sometimes also referred to as Satellite-On-The Move (SOTM) communications. Satellite communications have great commercial success in digital audio and video broadcasting as they exploit the inherent wide area coverage for distribution content. It was a natural consequence to extend its use to multimedia applications; DVB-S2/DVB-RCS standards offer a commercially proven solution for fixed terminals in that sense. In addition, communication on the move is becoming a key market sector. Therefore broadband mobile communications represent an additional market for the satellite, addressing primarily transport operators (planes, ships, trains) but also end-users in cars. To ensure economies of scale and fast development and deployment of equipments, the adaptation of current satellite broadcast and interactive broadband standards is foreseen. This paper presents possible techniques applicable to different market segments for both the forward and the return links of the system, with associated performance and impact on the standards. [ABSTRACT FROM AUTHOR]

Technical details of the recently announced Chinese Digital Terrestrial Television Broadcasting Standard which defines the physical layer transmission protocol including the frame structure, channel coding and modulation schemes are discussed in this paper. The major differences between Chinese DTV standard in multi-carrier working mode and DVB-T standard, all occupying the same 8 MHz baseband bandwidth, are addressed. The measurement results of several working modes showing satisfactory receiving performance of high and standard definition TV signals under both indoor and outdoor environments for the fixed and mobile reception are also presented. [ABSTRACT FROM AUTHOR]

This paper studies efficient and simple data broadcast in IEEE 802.15.4-based ad hoc networks (e.g., ZigBee). Since finding the minimum number of rebroadcast nodes in general ad hoc networks is NP-hard, current broadcast protocols either employ heuristic algorithms or assume extra knowledge such as position or two-hop neighbor table. However, the ZigBee network is characterized as low data rate and low cost. It cannot provide position or two-hop neighbor information, but it still requires an efficient broadcast algorithm that can reduce the number of rebroadcast nodes with limited computation complexity and storage space. To this end, this paper proposes self-pruning and forward node selection algorithms that exploit the hierarchical address space in ZigBee networks. Only one-hop neighbor information is needed; a partial list of two-hop neighbors is derived without exchanging messages between neighboring nodes. The ZigBee forward node selection algorithm finds the minimum rebroadcast nodes set with polynomial computation time and memory space. Using the proposed localized algorithms, it is proven that the entire network is covered. Simulations are conducted to evaluate the performance improvement in terms of the number of rebroadcast nodes, number of duplicated receivings, coverage time, and communication overhead. [ABSTRACT FROM AUTHOR]