Wireless Broadcast Systems Research Articles

Minimize BER without CSI for dynamic RIS-assisted wireless broadcast communication systems

This paper studies a dynamic reconfigurable intelligent surface (RIS)-assisted broadcast communication system where a transmitter broadcasts information to multiple receivers with time-varying locations via a RIS. The goal is to minimize the maximum bit error rate (BER) at the receivers by optimizing RIS phase shifts, subject to a given discrete phase shift constraint. Unlike most existing works where channel state information (CSI) is required, only location information of the receivers is needed in our work, due to the great challenge of instantaneous CSI estimation in RIS-assisted communications and the reason that statistical CSI does not apply to the dynamic scenario. The involved optimization problem is hard to tackle, because the BERs at the receivers cannot be calculated by classical CSI-dependent analytical expressions for lack of CSI and exhaustive searching is computationally prohibitive to achieve the optimal discrete phase shifts. To address this issue, a deep reinforcement learning (DRL) approach is proposed to solve the problem by reformulating the optimization problem as a Markov decision process (MDP), where the BERs are measured by the Monte Carlo method. Furthermore, to tackle the issue of the high-dimensional action space in the MDP, a novel action-composition based proximal policy optimization (PPO) algorithm is proposed to solve the MDP. Simulation results verify the effectiveness of the proposed PPO-based DRL approach.

An Efficient Design for the DVB-S2 Forward Link System Outer Layer Encoding Based on PCC Turbo Coding Across Fading Channel

The most significant challenges wireless broadcasting systems face are channel effects and Inter Symbol Interference (ISI). Many different kinds of channel coding are employed to get around these issues. Digital Video Broadcasting for Satellite Telecommunication Second Generation (DVB-S2) uses a serial concatenation of Bose, Ray-Chaudhuri, and Hocquenghem (BCH) code and Low-Density Parity-Check (LDPC) code as a Forward Error Correction (FEC) for error detection purpose and correction. In this work, a MATLAB code (m-files) is constructed to simulate the standard DVB-S2 Bit-Interleaved Coded Modulation (BICM) system according to the ETSI Technical Report (EN 302 307 1). Then, the traditional design is redesigned with a Parallel Concatenation Convolutional (PCC) Turbo coding in concatenation with LDPC coding to enhance the (FEC). The two approaches have been tested under the official modulation types QPSK, 8PSK, 16APSK, and 32APSK with 2/3, 3/4, 3/5, 4/5, and 5/6 code rates (RC). Over a Rayleigh Fading channel, the two models are compared. The proposed model performed better than the standard model regarding bit error rate (BER) mitigation when operating at varying signal-to-noise ratio (SNR) levels, especially in 8PSK 3/5 MODCODE. The proposed model achieved (2.6272×10-3) BER mitigation value with power gain equal to 4 dB.

Shapley’s Value as a Resource Optimization Strategy for Digital Radio Transmission over IBOC FM

The hybrid in-band on-channel (IBOC) transmission system, which serves as a digital audio radio scheme, facilitates the simultaneous transmission of analog FM and digital audio. In IBOC systems, broadcasters transmit signals within allocated channel bands, posing a challenge in bandwidth allocation for digital audio transmission. To address this, cooperative game theory, supported by the bankruptcy game and Shapley’s value, is proposed as a strategy to optimize bandwidth allocation at each node or station. This approach considers service demand, the number of stations, and radio channel conditions in the FM band. The paper presents a scenario under saturated traffic conditions to evaluate the degree of optimization achievable using the Shapley value under clearly defined traffic and channel conditions. The results indicate that cooperative game theory, with the support of the Shapley value, offers an excellent alternative for optimizing bandwidth in digital broadcasting over IBOC in FM, with potential applicability in other digital radio broadcasting systems.

Implementation on SDR platform of algorithms for noncoherent reception of optimal signals built on the basis of eigenfunctions

Formulation of the problem. When transmitting data at speeds above the Nyquist barrier, the algorithmic and computational complexity of radio modems increases significantly, especially with incoherent signal reception. Non-coherent reception algorithms can be implemented on a software-defined radio platform, on which optimal signals are formed and received. The ability to programmatically change the radio frequency parameters of signals without making structural changes to the transmit-receive path can significantly reduce the computing resources of radio modems. The goal is to determine the possibility of practical implementation on the SDR platform (Software Defined Radio) of noncoherent processing algorithms with decision feedback with the choice of optimal values of the observation interval for symbol rates R>1/T using optimal signals built on the basis of eigenfunctions. Results. The possibility of using differential modulation of optimal signals, the forms of which are obtained as a result of solving an optimization problem in accordance with the criterion of the maximum decay rate of the spectrum level outside the occupied frequency band, is shown for packet data transmission protocols and the use of an incoherent processing algorithm in channels with additive Gaussian noise. It is shown that when using algorithms of incoherent element-by-element processing with optimization of the observation interval, it is possible to ensure stable reception of binary optimal signals up to transmission rates exceeding the Nyquist barrier by 1.66 times and for an error probability of 10–3, the energy loss is about 18 dB relative to potential noise immunity. The digital modem of optimal spectrally efficient signals, built on the basis of the SDR platform, makes it possible to conduct spectral and energy efficiency studies in real time in the presence of additive channel noise, and the influence of clock synchronization inaccuracies during packet messaging leads to energy losses of no more than 1 dB. Practical significance. The use of differential modulation of optimal signals can be used in digital television and radio broadcasting systems in the European digital television standards DVB-S2 (Digital Video Broadcasting Satellite Second Generation), DVB-T2 (Digital Video Broadcasting Terrestrial Second Generation).

Audio Feature and Correlation Function-Based Speech Recognition in FM Radio Broadcasting

The analysis and classification of audio signals are becoming increasingly important, especially in the age of communication and dissemination of information through radio broadcasting systems. It is therefore essential that systems and platforms are available to monitor the spread of fake or fraudulent news. A speech feature-based correlation (SFC) algorithm and a speech recognition framework are developed in this study, combining specific speech features and performance correlation to monitor real-time radio broadcasting and recognize specific speech based on human samples. The speech features include the Mel frequency cepstral coefficient, gammatone cepstral coefficient, spectral entropy, and pitch. The results illustrate the advantages and disadvantages of each feature applied to the various speech sound groups. Furthermore, each feature combined with the design of SFC further enhances system performance and increases accuracy.

Методика расчета влияния фактора сезонности на распространение радиоволн в южных регионах России вблизи гидросферных объектов в диапазоне ультравысоких частот

The article substantiates the assertion that for radio communication design areas in the territory close to the hydrospheric objects (rivers, lakes, sea areas) it is necessary to use calculation methods taking into account the difference in the level of signal attenuation due to seasonality. This is especially true for the Astrakhan region characterized by hot summers (to which it is advisable to add the last month of spring - May - and the first month of autumn - September, also characterized by high air temperatures). Seasonal features of radio wave propagation are determined by the continuous superrefraction above the water part of the radio line, which is formed due to the temperature inversion during the whole period of hot weather in the Astrakhan region. This is a fairly long period of time (at least 5 months a year) that must be taken into account in design systems to obtain an accurate picture of the signal level distribution in the ultra-high frequency range for such systems as television and radio broadcasting systems, cellular communication systems. Upon the results of the research and field tests it has been inferred that the effect of ultra-long-range propagation of radio waves in a tropospheric waveguide does not depend on the frequency range of the radiating system. A new method for calculating the attenuation of radio signals over the water surface in the near-water tropospheric waveguide has been developed.

Estimation of radio refractivity from satellite-derived meteorological data over a decade for West Africa

Radio refractivity, which is the bending of a radio signal as it propagates through media, is very important in works involving terrestrial atmospheric electromagnetic propagation such as point-to-point microwave communication, terrestrial radio and television broadcast and mobile communication system. This study focused on the West African region where it was found that the refractivity varies exponentially with height (N=NoeH/h) and from the coast towards the desert: the average surface refractivity (No) for West Africa was found to be around 342 N-units, while the average scale height (h) was found to be around 8.01 km. Generally, the refractivity gradient was found to range between −46.48 and −29.51 N-units/km (k-factor value of between 1.23 and 1.42) across West Africa, splitting the region between sub- and super-refraction. The variation in refraction type was found to follow a seasonal pattern across the West African region, with sub-refraction dominating during the dry season and super-refraction dominating most part in the coastal area during the wet season.

Social Media and Journalism Ethics in Nigeria: A Study of Journalists in Kwara State of Nigeria

Journalism is a term that has been used to describe the act of gathering and reporting news, either through the print media which includes newspaper, magazine or through the broadcast media to mention television, radio broadcasting system and recently journalism has been extended throughout the world through unrestricted use of social media, whereby the act of gathering and disseminating of news is done without restraint. Conversely, one important thing to note about journalism is the ethics that enhance the profession, its notes worthy to know that any information that is disseminated via any media should be ethically standard. The new media has on a large scale given the opportunity to a whole large number of people to practice journalism without them knowing the ethics that guide the profession, which is affecting the dynamics of the profession. Therefore this study is based on assessing the impact of a new communication system on journalism; whether social media promote the ethics of journalism profession and to know if social media journalists are in compliance with the journalism code of ethics in their dissemination of news and information. In this research, the survey method was adopted and the north-central geo-political zone, Kwara state to be précised was selected for the study.

Dispelling Revisionist Myths Regarding Spectrum Property Rights in the 1920s

When assessing legislation and policies of the past, one must analyze the context in which they were developed. Failure to understand the past and the path to the present may lead to misunderstanding a regulatory agency’s structure and values. Such failures to understand the past have resulted in assertions that property rights and spectrum markets would have been superior to the regulatory system of the Radio Act of 1927. The author explores the relative efficiency implications of Federal Radio Commission regulation under the Radio Act of 1927 and a system of spectrum property rights. He observes that discussions of hypothetical spectrum property rights in the 1920s fail to take into account (1) the vast differences between the radio propagation conditions in the radio spectrum in use then and propagation in the bulk of the radio spectrum today and (2) the technical limitations of equipment at that time. Propagation conditions in the AM band make interference a diffuse problem. A single radio transmitter could impair the reception of dozens to hundreds of other stations; consequently, market transactions would have had to involve many parties. Hypothetical property rights systems also fail to consider directly the utility of the listening audience—the group responsible for more than 90% of the investment in the AM radio broadcasting system. The author concludes that spectrum property rights would have resulted in more radio service in urban areas, substantial loss of rural service, and diminished consumer welfare.

Dynamic MODCOD and power allocation in DVB-S2: a hybrid intelligent approach

Adaptive communication for is one of the hottest areas of research in the telecommunication systems including wireless broadcast systems. This is primarily accomplished for sake of boosting the transmission throughput with enhanced quality of service and ideal link utilization. In adaptive communication, various radio transmission parameters like modulation symbol, code-rate and power etc. are carefully chosen according to the erratic channel state information on the link. Digital video broadcast—second generation (DVB-S2) has an inbuilt support for adaptive coding and modulation (ACM). However, power adaptation is still a necessity because of power constraint in downlink where satellite has a limited power bank. Moreover, different downlinks have distinct transmit power requirements due to diverse ambient on earth receivers like rainy, foggy, stormy and with clear sky etc., hence flat transmit power distribution among all the ground receivers may not be a good idea at all. To utilize the ACM feature in DVB-S2 and to additionally adapt power, in this paper, an adaptive modulation, coding (MODCOD) and power scheme is proposed. By investigating a fuzzy system and differential evolution algorithm, to select the set of MODCODs and optimum power vector, respectively, for the next transmission interval. From the simulation results it is apparent that the proposed scheme is promising in terms of efficient link and transmit power utilization as well as quality of service compared to the schemes in the literature with flat power distribution.

IMS: An Identity-Based Many-to-Many Subscription Scheme With Efficient Key Management for Wireless Broadcast Systems

Subscription-based services, where broadcasting companies make profits by providing subscription programs to users, have become a popular application of wireless broadcast systems. Driving by business interests and data security, companies usually encrypt content of programs with session keys, then only authorized users can access the contents of their subscribed programs, respectively. It is challenging to flexibly distribute and update the session key, we are therefore motivated to propose an identity-based many-to-many subscription scheme (IMS) with efficient key management. The IMS scheme possesses three novel advantages: Firstly, it provides a whole set of subscription flow, from the selection of programs of interest to the generation and updating of keys. Secondly, it supports program updating and all subscription behaviors. Thirdly, it employs a signature and authentication mechanism to stipulate that only authorized users can access the programs ciphertext. The theoretical analysis demonstrates that the proposed scheme is secure against Chosen-Ciphertext Attacks (CCA) under the k-bilinear Diffie-Hellman exponent (BDHE) problem, and has a decent performance in storage and computational overhead. The experimental analysis shows the total time cost of the proposed scheme is reduced more than 75.02% compared against the popular peer schemes under the condition of 2500 users.

Broadcasting Directional Modulation Based on Random Frequency Diverse Array

Frequency diverse array- (FDA-) based directional modulation (DM) is a promising technique for physical layer security, due to its angle-range dependent transmit beampattern. However, the existing schemes are not suitable for the broadcasting scenario, where there are multiple legitimate users (LUs) to receive the confidential message. In this paper, we propose a novel random frequency diverse array- (RFDA-) based DM scheme to realize the point to multi-point broadcasting secure transmission in both angle and range dimension. In the first stage, the beamforming vector is designed to maximize the artificial noise (AN) power, while satisfying the power requirement of LUs for transmitting the confidential message simultaneously. In the second stage, the AN projection matrix is obtained by maximizing signal-to-interference-plus-noise ratio (SINR) at the LUs. The proposed scheme only broadcasts the confidential message to the locations of LUs while the other regions are covered by AN, which promotes the security of the wireless broadcasting system. Moreover, it is energy efficient since the power of each LU is under accurate control. Numerical simulations are presented to validate the performance of the proposed scheme.

Compressive optical steganography via single-pixel imaging.

A compressive optical steganography based on single-pixel imaging (SPI) is proposed. The SPI system, which employs a digital light projector to illuminate the host image with modulated patterns, is similar to a wireless broadcast system. Therefore, it is suitable for covert communication naturally. By leveraging the compressive sensing technique and a generalized phase retrieval algorithm, the secret message is sparse-sampled and then encoded into the illumination patterns, which are projected onto the host image in an SPI architecture. The resulting reflected light signals travel in the free space as a broadcast system, and the signals would be captured by the authorized receivers and the potential eavesdroppers. By implementing an inverse Fourier transform, a stegoimage will be received, which is almost the same as the host image. However, only the authorized receivers, who possess the secret key, could extract the desired data from the stegoimage and then reconstruct the secret message by using a convex optimization algorithm. Because the secret message is sparse-sampled before embedding, the imperceptibility is well preserved while the capacity also be kept in a high level. A series of simulation and experimental results verifies the validity and feasibility of the proposed method.

Spatial air index with neighbor information for processing k-nearest neighbor searches in IoT mobile computing

In the Internet of thing (IoT), with the geographic location of geospatial sensor data and the global positioning systems, location-based services (LBSs) can provide powerful location-aware IoT applications for mobile clients according to their current locations. For LBSs, a k-nearest neighbor (kNN) search can provide a mobile client with geospatial sensor data of k-nearest spatial points of interest (POIs) according to its current location. In this paper, we propose a spatial air index with neighbor information to organize IoT geospatial sensor data for processing kNN searches in the wireless broadcast systems. Since the answered POIs may be neighbors of each other, we add neighbor information to the index structure, which is interleaved with geospatial sensor data, to speed up the query processing. To avoid unnecessary examination of geospatial sensor data from the wireless channel, the proposed method provides the centroid of geospatial data and the corresponding longest distance between the centroid and geospatial data in the region. With this information, the query processing of a kNN search can quickly determine whether to skip examining this region, saving energy consumption of the mobile device. Performance evaluations have verified that the proposed method outperforms the distributed spatial index.

Online algorithm for data retrieval with multiple antennae in wireless communication

Given a set of requested data items and a set of multiple channels, online multi-antennae data retrieval problem (OMAP) is to download all requested data items from these channels when the clients are equipped with multiple antennae and do not know any a-prior knowledge of wireless data broadcast system, such that the total access latency is minimised and the access latency among all antennae keeps balance. So this paper proposes online multiple antennae data retrieval algorithm based on requested ratio (OMR) and online multiple antennae retrieval algorithm for equal data items based on unretrieved ratio (OMU) that introduces the requested ratio and unretrieved ratio respectively when the length of data items is equal. In addition, when the length of data items is unequal, the paper proposes online multiple antennae retrieval algorithm for unequal data items based on length ratio (OML) that introduces the length to compute the length ratio. Finally, we analyse the competitive rates of three algorithms. Through experiments, the proposed schemes can have currently better efficiency by comparing with some existing schemes and solve OMAP.

RESTRICTION OF UNAUTHORIZED ACCESS IN RADIO SYSTEMS WITH BROADCAST DATA TRANSMISSION

Introduction: The usage of broadcast radio systems is associated with the possibility of organizing continuous radio access zones with a limited number of transmission points and a considerable number of subscribers (information consumers). However, radio broadcasting systems have specific features of unauthorized access restriction related to the spatial electromagnetic accessibility of radio channels and the absence of a reverse information channel. Purpose: Developing principles for key information distribution and for the control over selective access of subscribers to the data transmitted in broadcast radio systems of various purposes, taking into account the restrictions imposed by the broadcasting mode of transmission. Method: Modification of the unauthorized access restriction methods used in radio broadcast systems, based on a combination of symmetric and asymmetric crypto algorithms. Results: The analysis of the existing approaches to unauthorized access restriction in broadcast radio systems has shown that the restrictions imposed by the peculiarities of these systems often make it difficult or impossible to apply various network protocols of protected data exchange commonly used in computer networks. We substantiate the principles (presence of two or more levels of key information; possibility to replace all the key information; ways to control the access to the system) and a way to restrict unauthorized access to the radio channels of broadcast systems, based on the combined use of symmetric and asymmetric crypto algorithms. As the symmetric part, you can use block or stream ciphers. As algorithms for the asymmetric part, elliptic curves are recommended, as they have the best cryptographic and speed characteristics as compared to other types of asymmetric cryptographic algorithms. Practical relevance: The proposed unauthorized access restriction method can be used to organize secure data exchange and selective control over the access to data transmitted in broadcast radio systems of various purposes.

Secured single-pixel broadcast imaging.

Active single-pixel imaging (also known as illumination-modulated single-pixel imaging) employs a spatial light modulator to illuminate a scene with structured patterns. The scheme of active single-pixel imaging is similar to a wireless broadcast system, allowing that multiple receivers use a single-pixel detector to capture an image simultaneously from a different place. The use of basis patterns allows for high-quality reconstructions and an efficient sampling process, but the public knowledge of the basis patterns is not a favorable feature for security applications. In order to develop a secured broadcast single-pixel imaging system, we propose to employ block-permutated Hadamard basis patterns for illumination. The randomness in permutation operations introduces strong security characteristics for the system. Both simulation and experimental results demonstrate our proposed scheme has satisfactory imaging quality and efficiency. This work generates a new insight for the application of single-pixel imaging and provides a solution for developing a secured imaging system for non-visible wavebands.

Nakagami-m channel secrecy: a receiver assisted scheme

This paper considers the effect of an end-user assisted jamming scheme to achieve a secure transmission of information over Nakagami-m fading channel in wireless broadcast system. In this work, full duplex (FD) antenna at the legitimate receiver (LR) was introduced in a way that the LR will contribute additional noise to the system to degrade the eavesdropper's channel. The approach achieves secured transmission with improved secrecy when compared to the conventional method that artificial noise (AN) scheme is transmitted from the transmitter only. Numerical analysis and simulation results show an improvement in the secrecy performance metrics.

Distributed and Adaptive Analog Coding for Video Broadcast in Wireless Cooperative System

Recently, some analog joint source-channel coding (AJSCC) schemes have been proposed to deal with cliff effect in wireless video broadcasting system. And wireless video broadcast with user cooperation tends to be a promising way to improve broadcast video quality in the near future. In this paper, we introduce a distributed and adaptive analog coding scheme called ACVC (adaptive cooperative video coding) based on AJSCC and with the concept of coset coding in distributed source coding, to improve the overall video broadcast quality in wireless cooperative system. Particularly, an adaptive packet discarding module is introduced to the framework to avoid video quality deterioration under severe channel conditions. And a model for quantization step selection of coset coding is built to minimize the redundancy in the cooperative signal and improve the anti-noise ability of the video. The experimental results show that, ACVC has stronger adaptability and thus obtains higher quality of broadcasted video than existing wireless cooperative schemes in the literature under different channel conditions.

CeilingTalk: Lightweight Indoor Broadcast Through LED-Camera Communication

Although Visible Light Communication (VLC) is gaining increasing attention in research, developing a practical VLC system to harness its immediate benefits using Commercial Off-The-Shelf (COTS) devices is still an open issue. To this end, we develop and deploy CeilingTalk as a lightweight wireless broadcast system using COTS LED luminaries as transmitters and smartphone cameras as receivers so that it can be fully hosted in a smartphone and is feasible for all possible indoor environments. CeilingTalk innovates in both encoding and decoding to achieve an adequate throughput for realistic applications. On one hand, it employs Raptor coding to allow multiple LED luminaries to transmit collaboratively so as to benefit both throughput and reliability. On the other hand, it involves a lightweight decoding scheme to handle the asynchrony (both spatial and temporal) in transmissions. Moreover, we analyze the impact of various parameters on the performance of CeilingTalk, in order to derive a model for such VLC systems enabled by COTS devices and hence provide general guidance for future VLC deployments in larger scales. Finally, we conduct extensive field experiments to validate the effectiveness of our LED-camera VLC model, as well as to demonstrate the promising performance of CeilingTalk: up to 1.0 kb/s at a distance of 5 m.