Digital Mobile Multimedia Broadcasting Systems

With the development of mobile communication technologies, mobile multimedia broadcasting services have become an important part of our life. This short report outlines the development process and status of the China Mobile Multimedia Broadcasting (CMMB) services in China, and summarises their successful innovation in CMMB. This work covers five areas of CMMB’s business, including technology, organization, service, finance, and business model.

Wireless backhaul and inter-tower communications networks were previously proposed as key enabling technologies for the next generation digital broadcasting systems, e.g. the Advanced Television Systems Committee (ATSC) 3.0 system. Due to the backward compatibility constraint, conventional symmetrical multi-input multi-output (MIMO) techniques cannot be applied directly in the existing broadcast infrastructure. In this paper, we propose a non-symmetrical approach to integrate MIMO in wireless backhaul and inter-tower communications networks. The proposed schemes maintain the existing broadcast infrastructure, while only adding a low-power RF feeding cable and one or more highly directional antennas to achieve low-cost MIMO implementation for high throughput data distribution and inter-tower networking for the next generation broadcasting systems. The advantages of the proposed system are low deployment cost and full backward compatibility with the ATSC 3.0 broadcast services.

With the advent of the digital age, service resources integration of mobile multimedia broadcasting is the objective needs of future development. Firstly, SOA architecture system is introduced on the basis of the overview of China mobile multimedia broadcasting (CMMB). Then, with the concepts of the hierarchical structure model of SOA, CMMB service resources integration model including basic information layer, component layer, service layer, business process layer, surface layer, application layer, enterprise service bus and infrastructure services, is built based on SOA. Finally, Web service technology used to implement the integration model is discussed.

In South Korea, Broadcast companies have begun a trial 3D broadcasting service by delivering dual streams, such as a left view sequence with MPEG-2 video and a right one with MPEG-4 AVC video, within the 19.4 Mbps terrestrial bandwidth. However, this limitation of transmission bandwidth in the terrestrial broadcasting system may cause quality degradation compared to the current 2D broadcasting service. Recently, the Advanced Television System Committee (ATSC) has released a new service model called non-real-time (NRT) technology, which provides file download functionality over a terrestrial broadcasting system. And electronic manufactures have developed smart TV which enables to receive RF channel and IP protocol. In order to operate a full quality 3D service, this paper proposes an NRT-based hybrid broadcasting system in which one of two view sequences is transmitted as a real-time broadcasting program, and the other is transmitted prior to a real-time broadcasting program and is stored as a file. This system uses a method of referential relation and synchronization between MPEG-2 transport stream (TS) and the file downloaded by ATSC NRT or IP. Therefore, the proposed hybrid broadcasting system can provide stable, high quality 3D content while maintaining a backward compatibility with the current 2D broadcasting system, despite the terrestrial bandwidth limitation.

This article describes the next‐generation terrestrial broadcast transmission system developed by the Advanced Television Systems Committee (ATSC) known as “ATSC 3.0.” The goals of ATSC 3.0 are to improve the television viewing experience with higher audio and video quality, compression efficiency, robust transmission for reception on both fixed and mobile devices, and more accessibility, personalization, and interactivity. ATSC is also addressing changing consumer behavior and preferences, providing TV content on a wide variety of devices. Furthermore, ATSC is working to add value to the broadcast service platform, extending its reach and adding new business models – all without the restriction of backward compatibility with the legacy system.

ATSC 3.0 is the Next Gen TV broadcast emission system defined by the Advanced Television Systems Committee (ATSC) encompassing the entire terrestrial broadcast system from the physical layer to the applications and presentation layer. This paper offers an overview of the important advancements in the ATSC 3.0 Standard, which is designed to inspire today’s content creators, business leaders, and consumers.

In this paper, the OFDM channel estimate method based on China Mobile Multimedia Broadcasting (CMMB) system is investigated. Wireless communication systems incorporating coherent OFDM requires the estimation and tracking of the time-varying channel response for accurate demodulation of data at the receiver. In pilot-symbol-assisted (PSA) OFDM systems, the MMSE estimator is a good channel estimation technique given that channel statistics are known. However, the major drawback of the MMSE estimator is its high computational complexity, which grows with number of pilots. The LMMSE estimator has lower computational complexity than the MMSE, and better performance than the LS. However, the LMMSE estimator directly applied for CMMB system performances worse than the LS. In comprehensive consideration of performance and computational complexity, an improved method is proposed. Simultaneously, the improved DFT-based estimator is simplified. The simulation is based on CMMB system. Simulation results show that our improved channel estimator performs better than the original one.

<p>Advanced Television Systems Committee (ATSC) 3.0, the new generation digital terrestrial television standard, has been designed for facing the new challenges of the future broadcasting systems. ATSC 3.0 has been built using the most recent cutting-edge technologies. Layered division multiplexing (LDM) is one of the major components of the new system baseline. LDM provides a tool to make flexible use of the spectrum for delivering simultaneous services to stationary and mobile services. This paper presents the performance evaluation of ATSC 3.0 core services in mobile scenarios using LDM. Simulation results are presented to analyze the influence of different LDM ensemble configuration modes for mobile reception. The simulation results have been also confirmed by laboratory tests under different channel models. The signal to noise ratio threshold values confirm the excellent behavior of ATSC 3.0 and LDM in mobile and portable scenarios.</p>

The physical layer [layer-1 (L1)] signaling (L1 signaling) of Advanced Television Systems Committee (ATSC) 3.0 is studied. In the new digital broadcasting system, ATSC 3.0, L1 signaling is designed to be more efficient but still robust compared with preceding standards such as DVB-T2. We introduce the error protection scheme of ATSC 3.0 in detail. Especially advanced methods newly employed in ATSC 3.0 are investigated with regard to its purpose and benefit in comparison to conventional DVB-T2.

As the 4G mobile communication systems require high transmission rate with reliability, the demand for efficient error correcting code increases. In this paper, a novel LDPC (Low Density Parity Check) decoding method is introduced. We address a parallel software implementation of LDPC decoding for CMMB (China Multimedia Mobile Broadcasting) standard. LDPC codes for CMMB employ a regular H-matrix which has the fixed row and column weights. While effectively utilizing the regularity of the H-matrix, we process information on H-matrices for multiple code rates using OpenMP pragmas on a multi-core processor and execute the decoding algorithm in parallel using CUDA (Compute Unified Device Architecture) on a GPU (Graphics Processing Unit). We evaluated the performance of the proposed implementation with respect to two different code rates, and verified that the proposed implementation satisfies the bandwidth requirement for CMMB.

Mobile TV is a developing service receiving a lot of attention and expectations. So far, different incompatible vertical standards exist that do not provide interoperability. In the Open Mobile Alliance, the Mobile Broadcast Services 1.0 (BCAST 1.0) standard has been developed and recently published. Its goal is to provide a common system for Mobile TV services at least 'above IP transport', so that the same service layer functionalities can be used for Mobile Broadcast and Mobile TV services over different broadcast and access networks. This paper describes the main components and aspects of the BCAST 1.0 standard. BCAST is a standard with practical relevance and in several countries operators have announced that they intend to launch Mobile TV services using BCAST starting in 2008.

Multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) is appealing for the provision of high spectral efficiency in digital terrestrial broadcast systems. To fully obtain its advantageous features, it is very important to remove the frequency mismatch between the transmitter and the receiver. In this paper, we present the performance analysis of joint estimation of carrier and sampling frequency offsets in the MIMO-OFDM-based advanced television systems committee (ATSC) 3.0 system. In the MIMO-OFDM ATSC system, the continual pilot (CP) is primarily utilized to perform frequency synchronization. To efficiently suppress an unwanted bias introduced by the presence of random-likely located CPs, an optimal pilot subset is selected to form the basis of least squares frequency-offset estimation. A closed-form mean squared error is derived in the context of MIMO-OFDM, considering the multipath fading channel. We show via computer simulations and numerical analysis that the proposed estimation method achieves higher estimation accuracy than the existing estimation method.

The next generation digital TV (DTV) broadcast, namely Advanced Television System Committee (ATSC) 3.0, relies on substantial single frequency networks (SFN), each of which requires a studio to transmitter link (STL) to transmit data from the broadcast gateway (BG), leading to significant construction costs. Therefore, the wireless in-band distribution link (IDL) technology is proposed, which uses layered-division multiplexing (LDM) to transmit the STL data via wireless links from the BG to the SFN transmitters within the same spectrum as the broadcast services. In this paper, we propose the time synchronization and signal detection algorithm for wireless IDL systems with both unicast and broadcast signals. We introduce two multiplexing schemes, N-LDM and 3-LDM, and demonstrate their superiority over traditional frequency division multiplexing (FDM). To overcome the challenge of multi-access interference and synchronization errors caused by multipath, we develop a unique word (UW) design algorithm for transmitted signals and a double threshold correlation detection algorithm (DTCDA) that outperforms traditional ones. We employ a second threshold to enhance detection performance at low signal-to-noise ratios, and utilizes successive interference cancellation (SIC) to mitigate multiple-access interference. More importantly, our approach requires no knowledge of the unicast user number or channel state information. Simulation results validate the effectiveness of the proposed scheme.

Superstorm Sandy, and similar disasters, have demonstrated the vulnerability of the nation's cellular telephone systems. Difficulties include overloads when usage suddenly increases; physical destruction of tower sites; and lack of sustained backup power. In contrast, US terrestrial broadcasters have a proven track-record to supply emergency information reliably, over large geographical areas and for as long as needed, as witnessed in the New York and New Jersey areas as well as in New Orleans (Katrina). Furthermore, digital television service to the home is now extended to mobile digital television (mobile DTV) serving portable and handheld devices including those in high speed vehicles. Mobile DTV is currently deployed in 50 major US cities by more than 140 stations with many more in the planning stages. Recently, the ATSC (Advanced Television Systems Committee) has also standardized the Mobile Emergency Alert System (M-EAS). M-EAS can provide both the familiar text "crawl" emergency alerts, and more complex and useful rich media information such as maps and video. M-EAS can be implemented in stand-alone devices, in cellular telephones, and/or in accessory hardware for existing devices.

For the ability of broadcasting the large amount of data, China Mobile Multimedia Broadcasting (CMMB) has become an important complement technology of mobile service. CMMB broadcasting the data through the data cache, multiplexing, scrambling, which are leading more data-broadcasting delay. It makes the real-time stock, ticketing, road business cannot be carried out. In this paper, we analyze the CMMB data-broadcasting delay distribution, which makes derivation of the multiplexing takes the most delay of the broadcasting. And the current methods to reduce multiplexing delay are low-efficiency, long- queuing time and poor algorithm-realization, this article puts forward a rapid service multiplexing method for multimedia broadcasting based on queuing theory, which improve the control and schedule in the multiplex with the queue model to reduce the multiplexing delay. The simulation and application confirm the method proposed by the paper can be reduced to the multiplexing delay of 3 seconds.