Jae-Kark Choi

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For handover in IEEE 802.16e, scanning procedure by mobile station is defined to find the most reliable target base station. However, the conventional scanning schemes cannot guarantee a fast target base station decision because some of the neighbor base stations of the scanning list provided by a serving base station are not actually attachable by the(More)
In this paper, we propose a new indoor cognitive radio network architecture that operates over a separated lower data rate band (ISM), which is mainly used for the common control information transmission, and multiple high speed data channel bands (UHF) at the same time. For cooperative indoor CR network operations, we have defined four procedures: network(More)
In wireless sensor networks, the positioning scheme using the received signal strength (RSS) has been widely considered due to its simplicity. Appropriate estimation of path-loss exponent (PLE) between a sensor node and an anchor node plays a key role in reducing position error in this RSS-based positioning. In the conventional researches, a sensor node(More)
In this paper, we proposed a group node contention algorithm for avoiding continuous collisions in LR-WPAN. The purpose of IEEE 802.15.4 is to achieve low speed, low cost and low power consumption. Recently, as applications of LR-WPAN have been extended, there is a high probability of collision as well. There are two types of collisions in LR-WPAN: i)(More)