Wireless Broadcast Systems Research Articles

An Improved Joint Detection of Frame, Integer Frequency Offset, and Spectral Inversion for Digital Radio Mondiale Plus

In digital radio broadcasting systems, long delays are incurred in service start time when tuning to a particular frequency because several synchronization steps, such as symbol timing synchronization, frame synchronization, and carrier frequency offset and sampling frequency offset compensation are necessary. Therefore, the operation of the synchronization blocks causes delays ranging from several hundred milliseconds to a few seconds until the start of the radio service after frequency tuning. Furthermore, if spectrum inversed signals are transmitted in digital radio broadcasting systems, the receivers are unable to decode them, even though most receivers can demodulate the spectral inversed signals in analog radio broadcasting systems. Accordingly, fast synchronization techniques and a method for spectral inversion detection are required in digital radio broadcasting systems that are to replace the analog radio systems. This paper presents a joint detection method of frame, integer carrier frequency offset, and spectrum inversion for DRM Plus digital broadcasting systems. The proposed scheme can detect the frame and determine whether the signal is normal or spectral inversed without any carrier frequency offset and sampling frequency offset compensation, enabling fast frame synchronization. The proposed method shows outstanding performance in environments where symbol timing offsets and sampling frequency offsets exist.

Baseband Transceiver Design of a High Definition Radio FM System Using Joint Theoretical Analysis and FPGA Implementation

Advances in wireless communications have enabled various technologies for wireless digital communication. In the field of digital radio broadcasting, several specifications have been proposed, such as Eureka-147 and digital radio mondiale (DRM). These systems require a new spectrum assignment, which incurs heavy cost due to the depletion of the available spectrum. Therefore, the in-band on-channel (IBOC) system has been developed to work in the same band with the conventional analog radio and to provide digital broadcasting services. This paper discusses the function and algorithm of the high definition (HD) radio frequency modulation (FM) digital radio broadcasting system. Content includes data format allocation, constellation mapping, orthogonal frequency division multiplexing (OFDM) modulation of the transmitter, timing synchronization, OFDM demodulation, integer and fraction carrier frequency (integer carrier frequency offset (ICFO) and fractional CFO (FCFO)) estimation, and channel estimation of the receiver. When we implement this system to the field programmable gate array (FPGA) based on a hardware platform, both theoretical and practical aspects have been considered to accommodate the available hardware resources.

Espacio audiovisual argentino: claroscuros de un presente exitoso y de un futuro incierto

The Argentine radio broadcasting system has historically been characterized by its private and commercial structure, with State actions that, in most processes, have tended to benefit this logic. Since the coming of democracy, the broadcasting law was modified to facilitate the creation of media conglomerates, allow the entry of foreign capital, and reinforce a system based on the search for profit. The outcome shows that the concentration of media property grew at a constant rate and that each new government reinforced the inherited structure. Now, if one considers an expanded audiovisual space, which includes the film sector, then the journey becomes more complex, given the diversity of policies implemented in each space. On the one hand, we find regulation and public action with negative aspects for democratization. On the other, a long-term State policy with benefits for national production and questions about the future. This paper outlines a tour of public communication policies in the Argentine audiovisual sector (film and TV). Firstly, it proposes a brief systematization of film policy. Secondly, it carries out an analysis of the period that began in 2008 and continues to this day, which has placed communication media at the center of debate. Lastly, a conclusion is offered, with a series of questions regarding the dilemmas faced by the sector in the current dynamic.

5.1 채널 오디오 신호를 스테레오 신호로 변환하는 디지털 다운믹서 개발

Use of the 5.1 channel audio signals suitable for the television system is improper for the radio broadcasting system, which uses the stereo audio system. Therefore, it is necessary to develop an audio down-mixer to convert 5.1 multi-channel audio signals to stereo signals for radio broadcasting. In this paper, a development of an audio down-mixer was carried out to convert 5.1 multi-channel audio signals to stereo signals. The down-mixer which was developed can use the audio signals separated from video signals, including sound signals or individual signals provided from 3-channel AES/EBU signals including Left(L), Right(R), Left Surround(Ls), Right Surround(Rs), Center(C) and Low Frequency Effect(Lfe) sounds as mixer inputs.

Static Reception Results of DRM+ Field Trials in VHF Band II in Brazil

The DRM+ (Digital Radio Mondiale) system is the extension up to 300 MHz of the DRM digital radio broadcasting system. During 2010 three different trials were conducted in Brazil with DRM+ system in VHF band II (popularly called FM band). These trials were defined to have a big, medium and small coverage area for big, local and community broadcasters. For this purpose, different transmission powers were used. The transmission was done with only DRM signal in low power trial. In the high and medium power trials the transmission was done in “combined mode”, that is, the FM and DRM+ signals were transmitted in adjacent channels from the same transmission site. In this paper the results of these trials are explained and compared with theoretical values.

A Novel Decoding Scheme for LT-Codes in Wireless Broadcasting Systems

In this letter, a novel decoding strategy for Luby transform (LT) codes in wireless broadcasting systems is presented and analyzed. The proposed hybrid-soft-and-hard-decoding (HSHD) scheme leverages cooperation between the MAC and the PHY layer, and achieves significant gains in spectrum efficiency and broadcasting coverage with marginal increase in complexity. Simulation results are provided to illustrate the excellent performance of HSHD in both AWGN and Rayleigh fading channels. The decoding complexity of HSHD is also quantified.

MIMO Broadcasting for Simultaneous Wireless Information and Power Transfer

Wireless power transfer (WPT) is a promising new solution to provide convenient and perpetual energy supplies to wireless networks. In practice, WPT is implementable by various technologies such as inductive coupling, magnetic resonate coupling, and electromagnetic (EM) radiation, for short-/mid-/long-range applications, respectively. In this paper, we consider the EM or radio signal enabled WPT in particular. Since radio signals can carry energy as well as information at the same time, a unified study on simultaneous wireless information and power transfer (SWIPT) is pursued. Specifically, this paper studies a multiple-input multiple-output (MIMO) wireless broadcast system consisting of three nodes, where one receiver harvests energy and another receiver decodes information separately from the signals sent by a common transmitter, and all the transmitter and receivers may be equipped with multiple antennas. Two scenarios are examined, in which the information receiver and energy receiver are separated and see different MIMO channels from the transmitter, or co-located and see the identical MIMO channel from the transmitter. For the case of separated receivers, we derive the optimal transmission strategy to achieve different tradeoffs for maximal information rate versus energy transfer, which are characterized by the boundary of a so-called rate-energy (R-E) region. For the case of co-located receivers, we show an outer bound for the achievable R-E region due to the potential limitation that practical energy harvesting receivers are not yet able to decode information directly. Under this constraint, we investigate two practical designs for the co-located receiver case, namely time switching and power splitting, and characterize their achievable R-E regions in comparison to the outer bound.

A Low-Complexity LDPC Decoding Algorithm for Hierarchical Broadcasting: Design and Implementation

In this paper, we present a structure-based decoding algorithm for the hierarchical broadcasting systems. Unlike the traditional hierarchical demodulation approaches that suffer from serious interlayer interference (ILI), the proposed method exploits the structure information on the secondary layer to mitigate the ILI impairment, thereby offering significant gains in reception performance. The algorithm can be applied to different channel coding and mapping schemes under various channel profiles. In addition, the new algorithm has been implemented on a broad-band in-band-on-channel digital radio broadcasting system. Numerical results from both simulations and laboratory experiments are provided to quantify the performance advantages of the new algorithm.

Supporting real-time multiple data items query in multi-RSU vehicular ad hoc networks (VANETs)

There has been increasing interest in the issue of multi-item queries in wireless broadcasting systems recently. Query starvation and bandwidth utilization have been identified as key issues for improved performance. In this paper, we examine this problem in the context of VANETs with multiple cooperating Road Side Units (RSUs). We characterize a query with two deadlines: Query Total Deadline (QTD) which is the actual deadline of a query and Query Local Deadline (QLD) which is the duration a query is valid for serving in an RSU. By considering these two deadlines together with vehicle speed, RSU range and inter-RSU distance, we formulate a Cooperative Query Serving (CQS) scheme which allows multiple RSUs to share residual bandwidth and effectively address the query starvation as well as the bandwidth utilization problems, hence maximizing the chance of serving multiple items queries. Extensive simulation results confirm that CQS outperforms other existing scheduling algorithms.

Mitigating jamming attacks in wireless broadcast systems

Wireless communications are vulnerable to signal jamming attacks. Spread spectrum mitigates these attacks by spreading normal narrowband signals over a much wider band of frequencies and forcing jammers who do not know the spreading pattern to expend much more effort to launch the attack. In broadcast systems, however, jammers can easily find out the spread pattern by compromising just a single receiver. Several group-based ideas have been proposed to deal with compromised receivers; they can tolerate up to t malicious receivers by adding 2t extra copies for each broadcast message. In this paper, we propose a novel scheme with random channel sharing. This scheme reduces the communication cost from 2t to (1 + p)t extra copies, where p determines the channel sharing probability (0 < p < 1). In addition, it does not increase the hardware complexity as it does not require a receiver to operate on multiple channels at the same time.

Radio on the Iberian Peninsula

This article aims to compare Portuguese and Spanish radio broadcasting systems from the mid-1970s to the present, from a political economy approach. It analyses the regulatory framework (communication policies) and the ownership structure. It explains how a highly similar situation has been reached despite having stemmed from a situation defined by different principles, when both political transitions began. To do so, this work also analyses the role of deregulation and its globalising nature. The study focuses on three key periods: the initial period in both transitions, the years following both countries’ admission into the European Community and the start of the new century.

Neighbor-Index Method for Continuous Window Queries over Wireless Data Broadcast

A continuous window query is an important class of spatial queries for location-based services. It retrieves spatial objects in a fixed window region of every point on a line segment and indicates the valid segments of them. In this paper, we focus on continuous window queries in wireless data broadcast systems. Since the query result of the continuous window queries has the spatial locality, providing neighbor information of spatial objects can guide clients to efficiently retrieve related objects. Therefore, we propose a neighbor-index method to efficiently support the continuous window queries in wireless data broadcast systems. The proposed method interleaves the neighbor information between spatial objects to guide mobile clients to quickly retrieve the answered objects and save the power consumption of the mobile devices. Experimental results show that our method outperforms the distributed indexing.

Digital Radio Broadcasting for Community Radios Using Pseudo-random Codes

This paper aims to present a digital radio broadcasting system that explores the advantages of pseudo-random codes. In this context, a transmitter and its dual receiver are able to reuse frequency spectrum bands without interfering on other existing communication systems. It is proposed a communication system that allows radio broadcasting with the following characteristics: lower transmission power, new communication channels and digital signal processing techinques to add positioning services in two dimensions.

스마트폰을 이용한 소규모 실시간 라디오 방송 시스템

This paper is a research on the design and implementation of a small real-time radio broadcasting system by using smart phone based on Android. It was designed as the server-client structure, and used the progressive download of HTTP as methods of transferring data to further simplify the system. In order to realize the real-time broadcasting, the original audio source was divided with a short interval and captured to be compressed and stored into files. Then the client receives and plays the compressed files sequentially as it is downloaded. However, this method occurs two problems each of which is the loss of capturing the original source in the server and the discontinuity of playing the files in the client. We solved the problem in the server by separating the thread into two parallel threads of which is each captured and compressed/stored, also by using the double buffering method. The problem in the client was solved using MediaPlayer in Android and the file queue to store the multiple files.

Single-carrier frequency domain equalisation with hierarchical constellations: an efficient transmission technique for broadcast and multicast systems

Orthogonal frequency division multiplexing (OFDM) schemes are the choice modulation for broadband wireless broadcast and multicast systems. However, OFDM schemes have important limitations such as high-envelope fluctuation of the transmitted signals and its sensibility to carrier frequency errors. When these limitations prove critical the authors consider single-carrier frequency-domain equalisation (SC-FDE) schemes, that allow much higher power efficiency because of lower envelope fluctuations. The overall performance can be further improved if the conventional linear FDE is replaced by an iterative FDE such as an iterative block decision feedback equaliser (IB-DFE). Conventional IB-DFE are usually designed for a quadrature phase shift keying constellation. However, it is strongly recommended that broadcast and multicast systems employ hierarchical constellations with several classes of bits with different error protection. In this study the authors consider the use of SC-FDE schemes combined with IB-DFE receivers in broadband wireless broadcast and multicast systems. The authors emphasise the advantages of these schemes and the authors present IB-DFE designs suitable for hierarchical constellations with several classes of bits with different error protection.

Optimization of discrete broadcast under uncertainty using conditional value-at-risk

The paper considers the problem of scheduling packets in wireless broadcast systems under uncertainty with the conditional value-at-risk (CVaR) constraints. In such systems, a server periodically transmits a stream of packets over a broadcast channel. The client that needs to access the data, tunes in to the channel and waits for the next packet. This allows one to serve a large number of clients in an efficient way and also keep clients’ location secret. We formulate and solve two alternative stochastic optimization problems that minimize the transmission time subject to CVaR constraints. Our results indicate that it is possible to derive an analytical solution to the problems in certain cases of practical interest. We also propose a methodology to obtain numerical solutions for the general case.

Intelligent Data Receiver Mechanism for Wireless Broadcasting System

Broadcast disk technology has become a popular method for data dissemination in wireless information systems. However, factors such as intentional periodic disconnection by the mobile hosts result in further needs for managing access modes to let the mobile hosts procure highest benefit through the disconnections. In this paper, we propose a new broadcast indexing structure, Data Receiver Indicator (DRI), which allows mobile clients to determine the time interval of active and sleep mode for connection according to turnaround time. Our goal is to develop an intelligent data retrieve protocol that allows mobile users to acquire more valuable data with less power consumption within a limited turnaround time. Our performance results show that DRI substantially outperforms the traditional indexes and especially gets 75% saving on waiting time. Therefore, with our approach, users may acquire more valuable data with less power consumption and reduced waiting time which means faster query and response.

Processing generalized k-nearest neighbor queries on a wireless broadcast stream

In this paper, we investigate the problem of processing generalized k-nearest neighbor (G kNN) queries, which involve both spatial and non-spatial specifications for data objects, in a wireless broadcasting system. We present a method for processing G kNN queries on the broadcast stream. In particular, we propose a novel R-tree variant index structure, called the bit-vector R-tree (bR-tree), which stores additional bit-vector information to describe non-spatial attribute values of the data objects. In addition, each node in the bR-tree stores only one pointer to its children, which makes the bR-tree compact. We generate the broadcast stream by multiplexing the bR-tree and the data objects in the broadcasting channel. The corresponding search algorithm for the broadcast stream is also described. Through a series of comprehensive simulation experiments, we prove the efficiency of the proposed method with regard to energy consumption, latency, and memory requirement, which are the major performance concerns in a wireless broadcasting system. Furthermore, we test the practicality of the proposed method in a real prototype system.

국내 HD Radio 시스템을 위한 효율적인 채널 배치 방안

현재 국내 라디오 방송은 디지털 방식이 아닌 아날로그 방식을 통해 서비스 되고 있다. 아날로그 방식은 디지털 방식에 비해 주파수 효율이 저하되는 등의 기술적인 한계를 가지고 있다. 디지털 라디오 방식중 하나인 HD Radio는 기존의 아날로그 스펙트럼 양 옆에 디지털 데이터가 실리는 방식으로 기존 아날로그 주파수의 재배치 없이 디지털 신호를 전송할 수 있다는 장점이 있다. 만약 아날로그와 디지털 신호가 동시에 존재하기 때문에 서로간에 간섭이 발생하면 원활한 수신이 불가능하므로 HD Radio와 기존FM방송 간의 간섭을 정확히 분석해야한다. 본 논문에서는 강릉 지역 괘방산 송신소를 기준으로 하고 전국의 103.5MHz 및 +-400kHz 이내의 주파수를 사용하는 기지국을 간섭국으로 지정하여 HD Radio 채널 배치 구조를 분석하였다. 본 논문을 통해 독자는 디지털 라디오 시스템의 주파수 간섭에 대한 참신한 정보를 얻을 수 있으리라 본다. The Korean radio broadcasting system is analog. Compared with digital radio, the analog radio decreases the frequency efficiency. HD Radio is the method where the digital signal is transmitted on either side of the analog PM signal. Therefore, without relocating the analog frequency can transmit digital signals. If interference between analog and digital signal occurs it is impossible to receive smoothly, so HD Radio interference with existing analog PM will be analyzed. In this paper, based on Mt.Gwae-Bang stations within +-400kHz frequency of l03.5MHz, and to use the station to station by specifying the HD Radio channel interference, place the structures were analyzed. Through this paper, the reader of a digital radio frequency interference in the system know that it may obtain information about.

World Radio Broadcasting System in the Netherlands [Scanning our Past

This is the story of Klaas Dijkstra (1894-1976) and the contents of his book entitled Radio Malabar which describes the technical evolution and daily life at a radio station on the isle of Java, Indonesia. The manuscript was a handwritten diary covering 1914-1945 and was discovered and published in 2000, long after the author's death, during the dismantling of the early National Netherlands Shortwave Transmitting Station known as Kootwijk Radio.