• Journal of KIISE:Information Networking
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• v.33 no.4
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• pp.333-342
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• 2006

The cdma2000 lxEV - DO mobile communication system provides broadcast and multicast services (BCMCS) to meet an increasing demand from multimedia data services. The servicing of video streams over a BCMCS network must, however, face a challenge from the unreliable and error-prone nature of the radio channel. The BCMCS network uses Reed-Solomon coding integrated with the MAC protocol for error recovery. We analyze this coding technique and show that it is not effective in the case of slowly moving mobiles. To improve the playback quality of an MPEG-4 FGS video stream, we propose the Hybrid error recovery scheme, which combines Reed-Solomon with ARQ, using slots which are saved by reducing the Reed-Solomon coding overhead. The target packets to be retransmitted are prioritized by a utility function to reduce the packet error rate in the application layer within a fixed retransmission budget. This is achieved by considering of the map of the error control block at each mobile node. The proposed Hybrid error recovery scheme also uses the characteristics of MPEG-4 FGS (fine granularity scalability) to improve the video quality even when conditions are adverse: slow-moving nodes and a high error rate in the physical channel.

• Journal of the Korea Society for Simulation
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• v.22 no.1
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• pp.41-51
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• 2013

This tutorial paper presents the design methodology of system-level simulators targeted for code division multiple access (CDMA) cellular standards such as EV-DO (Evolution-Data Only) and broadcast multicast service (BCMCS). The basic structure and simulation flow of system-level simulators are delineated, following the procedure of cell layout, mobile drops, channel modeling, received power calculation, scheduling, packet error prediction, and traffic generation. Packet data transmissions on the forward link of CDMA systems and EV-DO BCMCS systems are considered for modeling simulators. System-level simulators for cellular standards are modeled and developed with high-level languages and utilized to evaluate and predict air interface performance metrics including capacity and coverage.

• Journal of KIISE:Information Networking
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• v.33 no.1
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• pp.91-102
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• 2006

We analyze the performance of MAC-layer Reed-Solomon error recovery in the cdma2000 1xEV-DO Broadcast and Multicast Services (BCMCSs) environment, with respect to the size of the ECB (Error Control Block) and the air-channel condition, and establish the relationship between ECB size, error recovery capacity and service latency. From this we propose an adaptive error recovery scheme which adjusts the size of the ECB to reflect the environment of the mobile nodes so as to meet the required service quality (target bit error-rate), while reducing the latency of real-time applications. Extensive simulation results show the effectiveness of our approach compared to the current static scheme. Proposed adaptive schemes achieves near optimal solution with respect to service latency while satisfying the required service quality.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.1279-1282
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• 2007

무선 인터페이스 CDMA, WCDMA(HSDPA) 그리고 WiBro 는 대용량의 멀티미디어 컨텐츠를 제한된 무선자원에서 각 사용자에게 효율적으로 제공하기 위하여 Multicast 및 Broadcast 형태로 서비스를 제공하고 있으며, 이러한 서비스는 CDMA 에서는 BCMCS(Broadcast Multicast Service), WCDMA 에서는 MBMS(Multimedia Broadcast Multicast Service) 그리고 WiBro 에서는 MBS(Multicast Broadcast Service)라 불리고 있다. 본 논문에서는 각 서비스들의 DMB(Digital Multimedia Broadcasting)와 같은 방송형 서비스 및 다양한 멀티미디어 컨텐츠를 제공해 주기 위한 각 무선인터페이스의 Multicast 및 Broadcast 형태를 비교 및 분석하여 그에 따른 서비스의 확장성을 비교 분석하였다.