• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6C
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• pp.516-522
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• 2010

In this paper, the carrier frequency offset estimator is proposed for the China multimedia mobile broadcasting (CMMB). The fractional carrier frequency offset is estimated by utilizing the cyclic prefix in each CMMB symbol. In addition, the integer carrier frequency offset can be estimated with the synchronization signal in every CMMB frame. The proposed estimator is the most suitable for the frame structure of CMMB. It shows a prominent performance even in timing offset and multipath conditions.

• Journal of Korea Multimedia Society
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• v.15 no.3
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• pp.364-371
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• 2012

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.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.07a
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• pp.281-282
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• 2010

CMMB(China Multimedia Mobile Broadcasting)는 중국에서 개발된 이동 방송 시스템이다. CMMB는 시간 동기와 주파수 동기를 획득하기 위해 프레임에 포함된 두 개의 동기 신호와 OFDM 심볼을 이용한다. 이는 OFDM 심볼의 연속파일럿과 분산 파일럿을 이용하는 기존의 이동 방송시스템과 달리 CMMB를 위한 특화된 동기 알고리듬이 필요하다. 이에 본 논문은 CMMB의 프레임 구조에 적합한 시간 동기 알고리듬에 대하여 연구하였다. 제안 알고리듬은 CMMB의 동기신호를 이용하여 상관값을 구한 후 1차와 2차로 나누어 경계값을 초과 하는 값을 검색하여 프레임의 시작점으로 추정한다. 제안된 알고리듬은 컴퓨터 시뮬레이션으로 검증하였으며 다중 경로 상황에서도 우수한 성능을 보인다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.11a
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• pp.47-50
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• 2009

CMMB(China Multimedia Mobile Broadcasting) 방식은 중국의 휴대이동방송 표준으로서 프레임에 하나의 ID 신호와 두개의 동기 신호 40개의 OFDM(Orthogonal Frequency Division Multiplexing) 데이터 심볼을 포함하고 있다. 다른 OFDM 시스템의 모바일 방송과는 달리 CMMB는 별도의 동기 심볼을 두고 있다. 또한 BPSK 성상으로 전송되는 OFDM 심볼내의 연속 파일럿은 CMMB의 시스템 정보를 전송하고 있어 이미 수신기에서 송신 연속 파일럿을 알고있는 유럽의 DVB-H나 일본의 원세그와는 다르다. 그러므로 CMMB의 프레임 구조에 특화를 시킨 동기 알고리듬이 필요하다. 본 논문은 CMMB 동기신호를 이용한 정수배 주파수 동기, OFDM 심볼을 이용한 소수배 동기 알고리듬을 제안한다. 제안된 알고리듬은 각각 컴퓨터 시뮬레이션으로 검증하였다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.1
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• pp.22-30
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• 2011

In this paper, we propose a memory efficient multi-rate Low Density Parity Check (LDPC) decoder for China Mobile Multimedia Broadcasting (CMMB). We find the best trade-off between the performance and the circuit area by designing a partially parallel decoder which is capable of passing multiple messages in parallel. By designing an efficient address generation unit (AGU) with an index matrix, we could reduce both the amount of memory requirement and the complexity of computation. The proposed regular LDPC decoder was designed in Verilog HDL and was synthesized by Synopsys' Design Compiler using Chartered $0.18{\mu}m$ CMOS cell library. The synthesized design has the gate size of 455K (in NAND2). For the two code rates supported by CMMB, the rate-1/2 decoder has a throughput of 14.32 Mbps, and the rate-3/4 decoder has a throughput of 26.97 Mbps. Compared with a conventional LDPC for CMMB, our proposed design requires only 0.39% of the memory.

• IEMEK Journal of Embedded Systems and Applications
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• v.11 no.6
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• pp.325-334
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• 2016

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.

• Resources Recycling
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• v.4 no.4
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• pp.70-75
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• 1995

Waste tires arc used as landifill, combustion and recycling. Rccenllg. lhc recycling of waste tires received a great attentmu fiam all industries. Thc rccgcling methods for w s l e tires are classified inla three culegoljz, a whole tirc, cmmb rubha and energy. T h ~ ssl iidy invesligvled the pruduclion ol Lhc ruhhcr block by using clumh cubbel oI wasle Ires. The process 01 manulacluring the ~uhher block was co~lsislerl ol several slepc: collecting lilts, ctuilnng and grinding hrcs, mixing crumh ruhher wlth bmder. and shaping under heat and pressure The effccl ol binder on ll~e ~uecl~ilnicaplr opcrlics o l r uhher hlock war also investigalcd. The economic feaqihility of a surface treiilmcnl and multilayas on the rubber block was dclcimincd