Seokjoo Shin

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Wireless Body Area Network (WBAN) is a special purpose sensor application network which can be applied for applications relating to the health care. WBAN should support immediate and reliable data transmission for medical service during an emergency situation. Hence this paper proposes a new MAC superframe structure which can handle emergency data as well(More)
One of the key issues in design of an orthogonal frequency division multiple access (OFDMA) based system is subcarrier and power allocation. Assuming knowledge of the instantaneous channel gains for all users, we propose a resource allocation scheme for an OFDMA based system to simultaneously provide two services, guaranteed performance (GP) and best effort(More)
A signal format based on PWM dimming and NRZ-OOK signals has been proposed and experimentally demonstrated. The signal format increases slot utilization. The signaling scheme utilizes the off-state of the PWM dimming period. Thereby, the data rate is increased compared with the case without data in the off-state of the PWM period, at the cost of dimming(More)
This paper proposes a novel contention window control scheme for backoff based CRA (Collision Resolution Algorithm). The proposed scheme demonstrates a distributed way to control random slot selection over the contention window in each contention stage with reference to normalized backoff value in the previous contention stage. Such control results an(More)
Vehicular Ad-hoc Network(VANET) enables a wireless communication between vehicles to improve driver's safety. For the safety, a message including safety-related information is broadcast between vehicles and forwarded for farther vehicles. VANET poses challenges that broadcast attempts from many vehicles cause collisions between packets and result in packet(More)
In this letter, a scheme for Collision Mitigation with Intelligent Contention Window Control (COMIC) is proposed for backoff based collision resolution algorithm. COMIC intelligently mitigates collisions by probabilistically maximizing the selection likelihood of relatively less collision-probable contention slots over the backoffed contention window. A(More)
The random access channel (RACH) in OFDMA systems is an uplink contention-based transport channel that is mainly used for subscriber stations to make a resource request to base stations. In this paper, we focus on analyzing the performance of RACH in OFDMA systems such that the successful transmission probability, correctly detectable probability and(More)