China Mobile Multimedia Broadcasting Research Articles

Research on Micro-motion Modeling and Feature Extraction of Passive Bistatic Radar Based on CMMB Signal

Passive bistatic radar has unique advantages in studying Micro-Doppler effect because of its system characteristics. China Mobile Multimedia Broadcasting (CMMB) as a broad range of radio and television signal, its signal adopts multi-carrier Orthogonal Frequency Division Multiplexing (OFDM) technology, can be used as a good illuminator. Based on the CMMB signal, the scattering point model of helicopter’s echo is established, and the influencing factors of Micro-Doppler frequency are analyzed. On this basis, the Singular-spectrum Analysis combined with Time-frequency analysis and autocorrelation method is used to extract the target micro-motion characteristics. The simulation results verify the rationality of the micro-motion model and the effectiveness of the feature extraction method in this paper.

Performance Comparison of Turbo coder and low-density parity check codes

Wireless communication systems will suffer from the noise introduced in the channels. Channel codes are the essential part of wireless communication systems which help in detection and correction of errors due to the noise introduced in the channel. Turbo codes and LDPC codes are the Forward Error Correction (FEC) channel coding techniques which have the error correcting capability near to Shannon codes along with improvement in transmission rate and energy efficiency.Turbo codes were introduced in 1993[1]. LDPC codes were discovered in 1960 by R.Galleger in his Ph.D dissertation at MIT.They became implementable, after the discovery of Turbo codes[2]. The satellite communications such as DVB-RCS, telecommunications such as 3G, 4G, Wireless metropolitan standards IEEE 802.16(WiMax) uses turbo codes[3]. G.hn/G.9960 (ITU-T standard for networking over power lines, phone lines and coaxial cable), 802.3 an(10GBps ethernet over twisted pair), CMMB(China multimedia mobile broadcasting), DVB-S2/DVB-T2/DVB-C2(Digital video broadcasting , second generation), DMB-T/H(Digital video broadcasting), Wimax(IEEE 802.16e standard for microwave communications), 802.11n-2009(wi-Fi standard) are the few standards where the LDPC codes are employed.[4]

A Novel Carrier Loop Algorithm Based on Maximum Likelihood Estimation (MLE) and Kalman Filter (KF) for Weak TC-OFDM Signals.

Digital broadcasting signals represent a promising positioning signal for indoors applications. A novel positioning technology named Time & Code Division-Orthogonal Frequency Division Multiplexing (TC-OFDM) is mainly discussed in this paper, which is based on China mobile multimedia broadcasting (CMMB). Signal strength is an important factor that affects the carrier loop performance of the TC-OFDM receiver. In the case of weak TC-OFDM signals, the current carrier loop algorithm has large residual carrier errors, which limit the tracking sensitivity of the existing carrier loop in complex indoor environments. This paper proposes a novel carrier loop algorithm based on Maximum Likelihood Estimation (MLE) and Kalman Filter (KF) to solve the above problem. The discriminator of the current carrier loop is replaced by the MLE discriminator function in the proposed algorithm. The Levenberg-Marquardt (LM) algorithm is utilized to obtain the MLE cost function consisting of signal amplitude, residual carrier frequency and carrier phase, and the MLE discriminator function is derived from the corresponding MLE cost function. The KF is used to smooth the MLE discriminator function results, which takes the carrier phase estimation, the angular frequency estimation and the angular frequency rate as the state vector. Theoretical analysis and simulation results show that the proposed algorithm can improve the tracking sensitivity of the TC-OFDM receiver by taking full advantage of the characteristics of the carrier loop parameters. Compared with the current carrier loop algorithms, the tracking sensitivity is effectively improved by 2–4 dB, and the better performance of the proposed algorithm is verified in the real environment.

A Novel FLL-Assisted PLL With Fuzzy Control for TC-OFDM Carrier Signal Tracking

The time and code division-orthogonal frequency-division multiplexing (TC-OFDM) signal is a promising wireless positioning signal, which multiplexes the China mobile multimedia broadcasting signal and pseudorandom noise codes in the same frequency band. The drastic change of carrier-to-noise ratio can increase carrier tracking error of the TC-OFDM receiver and may lead to the loss of lock. To address this problem, a novel frequency-lock loop (FLL)-assisted phase-lock loop (PLL) with fuzzy control is proposed, and the effect of signal strength on the carrier tracking loop is analyzed. The proposed algorithm uses the outputs of the phase and frequency discriminator as measured residuals of the Kalman filter (KF), and a KF-based second-order FLL-assisted three-order PLL carrier tracking loop is designed. Moreover, fuzzy control is applied to the designed loop. It can automatically switch between pure KF-based PLL, pure KF-based FLL, and KF-based FLL-assisted PLL, and automatically adjust the noise bandwidth. Simulation and experimental results show that, compared with the existing carrier tracking algorithms, the proposed algorithm can effectively avoid the divergence of the tracking loop and improve the robustness of the TC-OFDM receiver.

A Pseudorange Measurement Scheme Based on Snapshot for Base Station Positioning Receivers.

Digital multimedia broadcasting signal is promised to be a wireless positioning signal. This paper mainly studies a multimedia broadcasting technology, named China mobile multimedia broadcasting (CMMB), in the context of positioning. Theoretical and practical analysis on the CMMB signal suggests that the existing CMMB signal does not have the meter positioning capability. So, the CMMB system has been modified to achieve meter positioning capability by multiplexing the CMMB signal and pseudo codes in the same frequency band. The time difference of arrival (TDOA) estimation method is used in base station positioning receivers. Due to the influence of a complex fading channel and the limited bandwidth of receivers, the regular tracking method based on pseudo code ranging is difficult to provide continuous and accurate TDOA estimations. A pseudorange measurement scheme based on snapshot is proposed to solve the problem. This algorithm extracts the TDOA estimation from the stored signal fragments, and utilizes the Taylor expansion of the autocorrelation function to improve the TDOA estimation accuracy. Monte Carlo simulations and real data tests show that the proposed algorithm can significantly reduce the TDOA estimation error for base station positioning receivers, and then the modified CMMB system achieves meter positioning accuracy.

OpenCL을 활용한 CPU와 GPU 에서의 CMMB LDPC 복호기 병렬화

Recently, Open Computing Language (OpenCL) has been proposed to provide a framework that supports heterogeneous computing platforms. By using an OpenCL framework, digital communication systems can support various protocols in a unified computing environment to achieve both high portability and high performance. This article introduces a parallel software decoder of Low Density Parity Check (LDPC) codes for China Multimedia Mobile Broadcasting (CMMB) on a heterogeneous platform. Each step of LDPC decoding has different parallelization characteristics. In this paper, steps suitable for task-level parallelization are executed on the CPU, and steps suitable for data-level parallelization are processed by the GPU. To improve the performance of the proposed OpenCL kernels for LDPC decoding operations, explicit thread scheduling, loop-unrolling, and effective data transfer techniques are applied. The proposed LDPC decoder achieves high performance by using heterogeneous multi-core processors on a unified computing framework.

A Compact Dual-Band Printed Yagi-Uda Antenna for GNSS and CMMB Applications

A printed Yagi-Uda antenna with a meandered driven dipole and a concave parabolic reflector is proposed for dual-band operations of L1-band Global Navigation Satellite System (GNSS) and S-band China Mobile Multimedia Broadcasting (CMMB). The antenna is designed and fabricated on a thin dielectric substrate, and measured at 1580 MHz in the low band (L1-band) and 2645 MHz in the high band (S-band), respectively, with directivities of 6.7 and 4.9 dBi, front-to-back ratios of 13.1 and 10.3 dB, cross-polarization levels of -23.8 and -21.9 dB, bandwidths of 4.0% and 6.5%, and antenna efficiencies of -0.40 dB (91.2%) and -0.96 dB (80.2%), which are better than -1 dBi in terms of the three-dimensional (3-D) average gain. The occupied area of this dual-band antenna is the same as that of the previously proposed single-band one. With these properties, the proposed antenna is promising for combo applications of L1-band GNSS and S-band CMMB.

Construction of Network Coverage Information System for CMMB

The network size of China Mobile Multimedia Broadcasting (CMMB) has expanded rapidly, and population coverage ratio has significantly increased. Meanwhile requirements of users to CMMB network coverage have risen higher and higher. How to know the situation of CMMB network coverage accurately and resolve the problems of it timely and effectively has become the primary task for CMMB network coverage workers. In this paper, based on the design requirements of CMMB coverage analysis system and data system, the E-R diagram was adopted to realize the database design of three physical objects: coverage information, map information and user information. Furthermore, a logical structure model of database was created and the design process of database in CMMB coverage analysis system was analyzed in this paper, which can provide a reference for further development and optimization of CMMB coverage analysis system.

Research and Design on China Mobile Multimedia Broadcasting Network Planning

The network coverage condition of China Mobile Multimedia Broadcasting (CMMB) affects the signal quality of the CMMB terminal directly. The requirements of signal coverage are different in different regions, the co-channel interference and the interference caused by signal in adjacent areas must be considered in the planning of transmitting station. In the process of transmitting station construction, reasonable planning for network coverage is helpful to save costs and improves the quality of the network. In this paper, the planning principle of CMMB coverage network was analyzed firstly, and then an effective solution for network planning was presented according to the specific needs and the condition of network construction in Fuzhou province. On the basis of controlling construction cost, the solution achieves the required network coverage ratio.

3D Video Transmission System for China Mobile Multimedia Broadcasting

With the popularization of three dimensional (3D) video on TV, some related aspects, such as broadcast television network transmission, technology application, and content products and so on, will face the challenges of the new technology. Rapid progress has been achieved in the China Mobile Multimedia Broadcasting (CMMB) technology, 3D TV technology applied in the mobile TV will become the bright spot in the future. This paper firstly introduces the transmission modes of 3D TV, and then gives the technology solution of 3D TV and the upgrade solution of electronic service guide Electronic Service Guide (ESG) based on CMMB. Test result shows that the new system with 3D video can work correctly when the 3D video was encoded with H.264 standard and the image resolution was conformed to the standard definition (320x240).

3D Video Transmission System for China Mobile Multimedia Broadcasting

With the popularization of three dimensional (3D) video on TV, some related aspects, such as broadcast television network transmission, technology application, and content products and so on, will face the challenges of the new technology. Rapid progress has been achieved in the China Mobile Multimedia Broadcasting (CMMB) technology, 3D TV technology applied in the mobile TV will become the bright spot in the future. This paper firstly introduces the transmission modes of 3D TV, and then gives the technology solution of 3D TV and the upgrade solution of electronic service guide Electronic Service Guide (ESG) based on CMMB. Test result shows that the new system with 3D video can work correctly when the 3D video was encoded with H.264 standard and the image resolution was conformed to the standard definition (320x240).

Experimental Research for CMMB-Based Passive Radar Under a Multipath Environment

China mobile multimedia broadcasting (CMMB) is a digital television standard that works in a single-frequency network (SFN) at the ultrahigh frequency band and adopts orthogonal frequency division multiplex modulation with a cyclic prefix (CP-OFDM). This paper investigates the practical feasibility of a CMMB-based passive radar (CPR) in the multipath propagation environment. First, several aspects involving system considerations induced by propagation conditions and radar signal characteristics are analyzed, including power budget, dynamic range requirement, clutter rejection metrics, and ambiguity function analysis. Then targeting the problems caused by multipath signals in the complex propagation environment and corresponding processing techniques are discussed, covering reference signal extraction and clutter rejection, as well as, tracking and localization. The highlight is clutter rejection with subcarrier-based spatial adaptive processing (SSAP), which is matched with the features of CP-OFDM. The applicability of SSAP under severe channel response spread mainly contributed by SFN is specially considered. Last, a description of the experiments and the CPR systems developed by Wuhan University is given, together with results from previous field trials for low-altitude aircraft and ship detection.

A handover algorithm in the converged networks of CMMB and TD-MBMS

With the development of information technology, the video services have become one of the most prevalent services in the era. Meanwhile, mobile TV technology has gradually become much more mature in China. In this paper, we first introduce the network architecture of time division-multimedia broadcast multicast service TD-MBMS and China Mobile Multimedia Broadcasting CMMB. Then, we make a comparison of these two standards. As a solution, we propose architecture of converged networks based on these two standards and present a handover algorithm based on the converged network architecture proposed. At the end of this paper, we utilise OPNET for the simulation in order to illustrate the performance of the proposed handover algorithm.

Dynamic voltage and frequency scaling scheme for an adaptive LDPC decoder using SNR estimation

Abstract In this paper, we propose a low-power adaptive low-density parity check (LDPC) decoder that utilizes dynamic voltage and frequency scaling to reduce power consumption. Most existing adaptive LDPC decoders have focused only on the decoding performance based on the signal-to-noise ratio (SNR) estimation. However, significant idle power is consumed when the decoder awaits the next frame after processing a frame. In mobile communication standards such as China Mobile Multimedia Broadcasting and Digital Video Broadcasting Satellite Second Generation, adaptive coding and modulation has been adopted. Thus, it is possible to reduce the power consumption efficiently by using the SNR estimation. In this paper, we apply a customized frequency selection scheme and a variable voltage generation scheme to an adaptive LDPC decoder to reduce the dynamic power consumption. The proposed schemes result in a reduction of 44% in the energy consumption of an LDPC decoder implemented using 0.18-μm complementary metal-oxide-semiconductor technology.

VLSI Architecture for Layered Decoding of QC-LDPC Codes With High Circulant Weight

In this brief, we propose a high-throughput layered decoder architecture to support a broader family of quasicyclic low-density parity-check (QC-LDPC) codes, whose parity-check matrices are constructed from arrays of circulant submatrices. Each nonzero circulant submatrix is a superposition of K cyclic-shifted identity matrices, where the circulant weight K ≥ 1. We propose a novel layered decoder architecture to support QC-LDPC codes with any circulant weight. We present a block-serial decoding architecture which processes a layer of a parity check matrix block by block, where each block is a Z×Z circulant matrix with a circulant weight of K. In the case study, we demonstrate an LDPC decoder design for the China Mobile Multimedia Broadcasting (CMMB) standard, which was synthesized for a TSMC 65-nm CMOS technology. With a core area of 3.9 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , the CMMB LDPC decoder achieves a maximum throughput of 1.1 Gb/s with 15 iterations.

Coherent Integration Implementation for China Mobile Multimedia Broadcasting Based Passive Radar with Nonuniform Sampling

摘要: 中国移动多媒体广播(CMMB)与欧洲数字视频地面广播(DVB-T) 的信号结构有显著区别，使得CMMB外辐射源雷达信号处理方法和实时并行计算面临一些新问题。该文针对CMMB信号的特殊结构，提出了一种易于并行实现的非均匀采样相干积累方法。首先阐述了算法的内在机理和处理流程，接着分析了该方法的分辨率与主旁瓣性能，最后通过实测数据处理验证了所提方法的有效性。 关键词: 外辐射源雷达 / 非均匀采样 / 相干积累 / 中国移动多媒体广播 / 数字地面电视

Impact of Transmission Distortion on Video Streaming Quality over China Mobile Multimedia Broadcast

This paper investigates the perceptual quality of video streams affected by wireless channel transmission distortion over CMMB (China Mobile Multimedia Broadcasting standards). First, transmission distortion is simulated using block error rate patterns representative of the wireless channel. Finally, we provide an asymptotic quality analysis of the video transmission through CMMB wireless channel. It can evaluate video streams quality of CMMB and get a good corresponding with the subjective assessments results. This type of quality assessment model based on transmission distortion has important applications in real-time wireless video communication.

A memory efficient parallel layered QC-LDPC decoder for CMMB systems

This paper presents a memory efficient architecture of layered decoder for the dual-rate LDPC codes in the China Multimedia Mobile Broadcasting (CMMB) system. An efficient scheme for reducing the memory block number is proposed to increase the memory usage efficiency, so that the quantity of memory bits, decoder area and power consumption is significantly reduced. At the same time, the memory structure keeps the “one cycle one layer access” timing schedule to achieve high decoding throughput. Furthermore, the early termination strategy is employed to further increase the throughput; a non-uniform quantization scheme and an area efficient calculation module are developed to further improve the memory efficiency and hardware resource efficiency, respectively. By using SMIC 130nm 1P7M CMOS process, the decoder is implemented and the core area is 5.29mm2. The total memory bits consumption is only 130.5K which consumes 2.53mm2 memory area.

Market competitiveness of mobile TV industry in China

Mobile TV is listed as China's national priority to develop the triple play system. Fast-growing China Mobile Multimedia Broadcasting services (CMMB) leads China's mobile TV industry and forms the largest network globally. As mobile TV regulation and technology became stable after the initial stage, this study focuses on CMMB's competitiveness in market/industry subsystem. Using document analysis and expert interviews, it analyzes CMMB's institution-driven and market-driven forces in the Chinese 3G/4G telecommunication market. The socio-technical framework is incorporated with seven forces model to examine commercialized CMMB and investigates its market and technoculture in Shanghai. Institutionally, CMMB business structure was collapsed into three levels which managed extensive and diverse Chinese markets strategically through a unified platform. After the business model switched to a subscription model, CMMB's rollout slowed down but turned it into a sustainable business. Besides, analysis of market forces shows CMMB's good market competiveness due to strong support from suppliers, complementors, and distribution channels and little threat from rivals, new entrants, and substitutes. CMMB users have increasing switching cost because of improved content/services and devices and no data charge fee. In contrast, CMMB faces stronger threat from competitors and substitutes and less loyal consumers in Shanghai than on a national level. CMMB's rapid developmental path provides meaningful implications for other countries in establishing mobile multimedia networks. This study recommends a pro-innovative and technology-neutral regulatory approach to develop mobile TV. Finally, the socio-technical model is found useful for analyzing technological development at different stages and contexts.

A 65 mW fully integrated UHF-band CMMB tuner in 65 nm CMOS process

A low power fully integrated digital TV tuner chip for China Mobile Multimedia Broadcasting (CMMB) application is presented. Based on direction conversion architecture, analog 8th-order filter/gain stages utilizing high power efficient operation-amplifiers and a ΣΔ fractional-N phase locked loop (PLL) with one voltage controlled oscillator (VCO) covering 4.8–7.2 GHz is proposed for low power and small chip area. The tuner is implemented in 65 nm CMOS process with low noise amplifier (LNA) matching network and phase locked loop (PLL) filter integrated on chip, occupying a chip area of 4.83 mm2. The measured noise figure (NF) is less than 3.2 dB over CMMB UHF band (470–798 MHz). A total power consumption of 65 mW (54 mA from 1.2 V supply) is achieved.