Mobile Multimedia Broadcasting Research Articles

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.

Different Code Rates of LDPC Decoding Based on CMMB Standard

In this paper, we present different code rates of LDPC decoding on Chinese Mobile Multimedia Broadcasting standard (CMMB). There are two different code rates (0.5 and 0.75) of LDPC in CMMB standard.In this paper, we use LLR-SPA algorithm to decode and make a simulation. Simulation results show that the higher code rate (0.75) of LDPC code in CMMB standard provides a better performance.

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.

RF power amplifiers behavioral modeling based on extended neural network with additional dynamic fuzzy weights

This paper presents an extended neural network (NN)-based behavioral model of RF power amplifiers (PAs) with memory effects. PA behavioral models are traditionally constructed based on the relationship between the input and output of PA, without regard to the physical mechanisms of distortions in PA however. To more accurately predict the dynamic nonlinear behavior of PA, the novel proposed NN-based behavioral model takes into account the characteristics of the amplitude modulation to amplitude modulation and amplitude modulation to phase modulation distortions that are incorporated into the behavioral model by means of additional dynamic fuzzy weights. In addition, the NN-based behavioral model employs orthonormal Hermite polynomial functions rather than commonly used sigmoid function, as nonlinear activation functions resulting in significant improvement in accuracy and convergence. Experimental results on a class-AB PA driven with the wideband Mobile Multimedia Broadcasting signals show a superior performance of the proposed extended NN-based model over the traditional NN-based ones.

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.

No-Reference Quality Assessment for Real-time Video Streaming over China Mobile Multimedia Broadcast

No-Reference Quality Assessment for Real-time Video Streaming over China Mobile Multimedia Broadcast

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.

인접 채널 간섭 제거를 통한 CMMB 수신기의 성능 향상에 관한 연구

중국의 디지털 모바일 방송 표준인 CMMB (China Mobile Multimedia Broadcasting)는 기존의 지상파 TV 방송인 Analog 방송과 동일한 주파수 대역 (474MHz ~ 754MHz)을 통해 송출되고 있다. 또한 기존의 Analog 방송의 수신 품질을 위해 디지털 방송의 송출 전력을 기존의 Analog 방송보다 낮게 하여 송출한다. 이러한 현상으로 인해 CMMB 수신기는 CMMB 수신신호와 인접하는 대역에 존재하는 Analog 방송 신호 영향을 받게 된다. 또한 셀의 경계에 있는 지역에서 CMMB 채널이 서로 인접해 있을 경우 수신기는 원하는 CMMB 신호 수신에 영향을 받게 된다. 이러한 인접 채널 간섭 (ACI : Adjacent Channel Interference)으로 인해CMMB 수신 성능에 영향을 미치며 이는 CMMB 수신기의 품질이 저하되는 문제로 이어지게 된다. 본 논문에서는 이러한 인접 채널 간섭현상을 간단하게 제거하기 위해 저주파 대역 통과 필터 (LPF : Low Pass Filter)의 차단 주파수를 조정하여 인접 채널에 의한 간섭을 최소화하였으며 이를 통해 CMMB 수신기의 수신 성능이 11.3dB 향상됨을 실험을 통해 알 수 있었다. Currently, CMMB(China Mobile Multimedia Broadcasting) and the conventional analog TV broadcasting have transmitted by using UHF(Ultra High Frequency : 474MHz~754MHz) band. Normally, the transmission power of the digital TV broadcasting is lower than the conventional analog TV broadcasting to protect the reception quality of the conventional analog TV broadcasting. The reception sensitivity of CMMB receiver has severely deteriorated due to adjacent the conventional analog TV broadcasting signals which called ACI (Adjacent Channel Interference). To improve the reception sensitivity of a CMMB receiver on ACI environment, this paper proposed a simple method which is tuning a cut off frequency of LPF (Low Pass Filter). From the experiment, the reception sensitivity of CMMB receiver was improved as 11.3dB.

Prospect of mobile TV broadcasting in China: socio-technical analysis of CMMB's development

Drawn from extensive document analysis and interviews with stakeholders, this socio-technical study examines the shaping powers of the subsystems (technology, policy/government, and market/industry) of China Multimedia Mobile Broadcasting (CMMB). After the Beijing Olympics, the first commercialized mobile TV expanded its infrastructure and business operations faster than other 3G and mobile TV broadcasting, covering 346 cities by November 2010. The findings show that CMMB, which is the leader in Chinese mobile TV development, is policy/government-driven and technologically ready. However, multiple technological standards and discrepancies between regulatory bodies slowed down its initial rollout. In the market/industry subsystem, content/services scarcity, undesirable pricing schemes, and low brand awareness are the inhibitors that curbed CMMB's diffusion. However, its strategic collaboration with China Mobile allowed it to quickly increase its user base and sale of CMMB-enabled handsets. Moreover, the socio-technical approach is a useful framework to investigate the forces that shape emerging technological trajectory holistically.

An Area-Efficient Reconfigurable LDPC Decoder with Conflict Resolution

Based on Turbo-Decoding Message-Passing (TDMP) and Normalized Min-Sum (NMS) algorithm, an area efficient LDPC decoder that supports both structured and unstructured LDPC codes is proposed in this paper. We introduce a solution to solve the memory access conflict problem caused by TDMP algorithm. We also arrange the main timing schedule carefully to handle the operations of our solution while avoiding much additional hardware consumption. To reduce the memory bits needed, the extrinsic message storing strategy is also optimized. Besides the extrinsic message recover and the accumulate operation are merged together. To verify our architecture, a LDPC decoder that supports both China Multimedia Mobile Broadcasting (CMMB) and Digital Terrestrial/ Television Multimedia Broadcasting (DTMB) standards is developed using SMIC 0.13µm standard CMOS process. The core area is 4.75mm2 and the maximum operating clock frequency is 200MHz. The estimated power consumption is 48.4mW at 25MHz for CMMB and 130.9mW at 50MHz for DTMB with 5 iterations and 1.2V supply.

Parallel LDPC decoding using CUDA and OpenMP

Digital mobile communication technologies, such as next generation mobile communication and mobile TV, are rapidly advancing. Hardware designs to provide baseband processing of new protocol standards are being actively attempted, because of concurrently emerging multiple standards and diverse needs on device functions, hardware-only implementation may have reached a limit. To overcome this challenge, digital communication system designs are adopting software solutions that use central processing units or graphics processing units (GPUs) to implement communication protocols. In this article we propose a parallel software implementation of low density parity check decoding algorithms, and we use a multi-core processor and a GPU to achieve both flexibility and high performance. Specifically, we use OpenMP for parallelizing software on a multi-core processor and Compute Unified Device Architecture (CUDA) for parallel software running on a GPU. We process information on H-matrices using OpenMP pragmas on a multi-core processor and execute decoding algorithms in parallel using CUDA on a GPU. We evaluated the performance of the proposed implementation with respect to two different code rates for the China Multimedia Mobile Broadcasting (CMMB) standard, and we verified that the proposed implementation satisfies the CMMB bandwidth requirement.

Overlapped message passing technique with resource sharing for high speed CMMB LDPC decoder

Today, demands for high speed digital communication are getting bigger due to wide deployment of 4G mobile communications and mobile TV services. Requirement for high speed data processing makes forward error correction crucial. LDPC is one of the most popular error correcting codes. In this paper, we propose a novel LDPC decoder for the China Multimedia Mobile Broadcasting (CMMB) standard. The LDPC decoding is carried out iteratively, which leads to relatively long decoding latency. Also, due to long code words, the amount of required memory is huge. To resolve these issues, we propose a novel Overlapped Message Passing (OMP) algorithm with an efficient resource sharing technique. Using the proposed method, we find the best permuted parity check matrix of the CMMB to improve the throughput while minimizing the memory requirement. Using the OMP algorithm only, we could improve the performance by 10%. To avoid potential memory access conflicts, a memory grouping technique to improve pipelining performance is also proposed. By applying all the techniques that we propose in this paper, we could improve the performance up to by 451.

An RF front-end with an automatic gain control technique for a U/V band CMMB receiver

This paper presents a fully integrated RF front-end with an automatic gain control (AGC) scheme and a digitally controlled radio frequency varied gain amplifier (RFVGA) for a U/V band China Mobile Multimedia Broadcasting (CMMB) direct conversion receiver. The RFVGA provides a gain range of 50 dB with a 1.6 dB step. The adopted AGC strategy could improve immunity to adjacent channel signal, which is of importance for CMMB application. The front-end, composed of a low noise amplifier (LNA), an RFVGA, a mixer and AGC, achieves an input referred 3rd order intercept point (IIP3) of 4.9 dBm with the LNA in low gain mode and the RFVGA in medium gain mode, and a less than 4 dB double side band noise figure with both the LNA and the RFVGA in high gain mode. The proposed RF front-end is fabricated in a 0.35 μm SiGe BiCMOS technology and consumes 25.6 mA from a 3.0 V power supply.

A low power 8th order elliptic low-pass filter for a CMMB tuner

This paper presents an 8th order active-RC elliptic low-pass filter (LPF) for a direct conversion China Mobile Multimedia Broadcasting (CMMB) tuner with a 1 or 4 MHz −3 dB cutoff frequency (f−3dB). By using a novel gain-bandwidth-product (GBW) extension technique in designing the operational amplifiers (op-amps), the proposed filter achieves 71 dB stop-band rejection at 1.7 f−3dB to meet the stringent CMMB adjacent channel rejection (ACR) specifications while dissipates only 2.8 mA/channel from a 3 V supply, its bias current can be further lowered to 2 mA/channel with only 0.5 dB peaking measured at the filter's pass-band edge. Elaborated common-mode (CM) control circuits are applied to the filter op-amp to increase its common-mode rejection ratio (CMRR) and effectively reject the large signal common-mode interference. Measurement results show that the filter has 128 dBμVrms in-band IIP3 and more than 80 dB passband CMRR. Fabricated in a 0.35-μm SiGe BiCMOS process, the proposed filter occupies a 1.19 mm2 die area.

7-4 VHF-Low帯マルチメディア放送の蓄積コンテンツ伝送におけるDDBサイズの検討(第7部門放送方式)

7-4 VHF-Low帯マルチメディア放送の蓄積コンテンツ伝送におけるDDBサイズの検討(第7部門放送方式)

7-3 VHF-Low帯マルチメディア放送の時間インターリーブに関する一検討(第7部門放送方式)

7-3 VHF-Low帯マルチメディア放送の時間インターリーブに関する一検討(第7部門放送方式)

7-2 FM波を用いたVHF-Low帯マルチメディア放送の電車内受信エリアの推定(第7部門放送方式)

7-2 FM波を用いたVHF-Low帯マルチメディア放送の電車内受信エリアの推定(第7部門放送方式)