Byung-Cheol Shin

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—We propose an adaptive redundancy control method for erasure-code-based real-time data transmission over the In-ternet. The loss rate is an important quality of service (QoS) parameter for real-time data transmission. However, real-time data transmission over best-effort networks, such as the Internet, suffers from a frequent packet loss due to traffic(More)
—A new signal-to-interference ratio (SIR)-based call admission control (CAC) scheme is proposed in DS-CDMA systems. In this scheme, a new call is accepted by a base station (BS) if the SIR's at that specific BS and its nearby, not necessarily adjacent, BS's can be guaranteed to be higher than some threshold value after accepting the new call. The SIR's of(More)
—As mobile telephone traffic demands increase in the future, interest in cellular systems with a hierarchical structure will grow. Hierarchical cellular system can provide high system capacity , efficient channel utilization, and an inherent load-balancing capability. In this type of system, calls blocked in a microcell flow over to a macrocell which is(More)
—The Intermational Mobile Telecommunications IMT-2000 system uses a microcell concept to provide multimedia services and to support increasing number of users. However, in a microcell system, the number of handoffs is greatly increased. To solve this problem, a multitier cellular structure is proposed, in which high-speed mobile terminals (MTs) are serviced(More)
—In this paper, we analyze the throughput of a direct-sequence spread spectrum multiple access (DS/SSMA) unslotted ALOHA system with variable length data traffic. The system is analyzed for two cases: 1) systems without channel load sensing protocol (CLSP) and 2) systems with CLSP. The bit-error probability and the throughput are obtained as a function of(More)