Ki-Yun Kim

Design of carrier recovery algorithm for high-order QAM with large frequency acquisition range

We propose a polarity decision carrier recovery algorithm that is useful for carrier acquisition in high order-QAM (quadrature amplitude modulation). The PD (phase detector) output and its variance characteristics are mathematically derived and the simulation results are presented. We design a carrier recovery loop with this polarity decision PD and ATC (automatic transfer-mode controller), which is proposed to detect a proper time for mode change and to yield fine phase tracking error in the steady state. While the conventional DD (decision directed) algorithm can only acquire frequency offsets of less than /spl plusmn/10 kHz, the proposed carrier recovery algorithm can acquire up to /spl plusmn/200 kHz without AFC (automatic frequency control). We show the RMS (root mean square) phase error performance using the proposed carrier recovery PLL (phase locked loop).

Technical Characteristics and Trends of Capsule Endoscope

Capsule Endoscope(CE) is a capsule-shaped electronic device which can examine the lesions in digestive tract of human body. Recently the medical procedure using capsule endoscope is receiving great attention to both doctors and patients, since the conventional push-typed endoscope using cables brings great pain and fear to the patients. The technique was firstly available in 2000 and is based on a convergence techniques among BT(Bio Technology), IT(Information Technology), and NT(Nano Technology). The device consists of an optical parts including LEDs(Light Emitting Diodes), an image sensor, a communication module and a power module. Capsule endoscope is the embodiment of the state-of-the art technology and requires key technologies in the various engineering fields. Therefore, in this paper, we introduce the composition of the capsule endoscope system, and compare the communication method between RF(Radio Frequency) communication and HBC(Human Body Communication), which are typically used for data transmission in the capsule endoscope. Futhermore, we analyze the specification of commercialized capsule endoscopes and present the future developments and technical challenges.

Network Resources Optimization for Random Linear Network Coding

In a multisource multicast network using random linear network coding, only the lower bounds on the decoding probability, the probability that all receivers can decode all source processes, have been known. We obtained new topology-independent and topology-dependent upper bounds on the decoding probability by using a simple counting argument. These upper bounds and the best known lower bound on the decoding probability are used to optimize the finite field size governing the use of network resources by exploiting a trade-off between computational complexity and the decoding probability.

A novel residual carrier synchronization technique for M-QAM-OFDM in the presence of intercarrier interference

We propose a new carrier phase synchronization algorithm which can recover residual frequency offset as well as phase offset by using proposed QD (quadrant decision) method. The salient feature of this method is that residual carrier frequency offset can be compensated by using an FFT demodulated signal without the aid of GI (guard interval) or pilots.

A low computational equalization method for capsule endoscope system

In this paper, we propose a low computational equalization method for capsule endoscope (CE) system. In CE system, low power transmission and reception is essential because the devices which are transplanted or patched on human body should be small and durable to allow the patient to move freely. Also, the pace of change in channel between CE and receiver is quite variable due to the bowel movements. Therefore, it is necessary to design a low computational equalizer structure for CE system, because there are difficulties in practical application of the conventional equalization due to its high computational complexity. Therefore, we propose an equalization method that focuses on reducing computational complexity. The proposed method adaptively decides the requirement of filter update with simple operation, and we verified that the proposed method improves the performance versus computational complexity trade-offs efficiently compared to the conventional method.

Offset Phase Rotation Shift Keying and Phase Silence Rotation Shift Keying Modulation for Medical In-Body WBAN Systems

In this paper, we proposed new modulation schemes, Offset Phase Rotation Shift Keying (OPRSK) and Phase Shift Rotation Shift Keying (PSRSK), for medical in-body wireless body area network (WBAN) systems. In IEEE, the WBAN system is assigned as 802.15. Task Group (TG) 6, and the related standardization is being progressed. Recently, in this Group, Phase Silence Shift Keying (PSSK), Phase Silence Position Keying (PSPK) and Phase Rotation Shift Keying (PRSK), which can obtain higher power efficiency, are proposed as new modulation schemes for low-power operation of WBAN system. However, they have a disadvantage for non-linear amplifier distortion. Therefore, in this paper, we proposed OPRSK and PSRSK, which are robust to non-linear amplification, by employing a phase offset in constellation and a power distribution in symbol duration, and verified that the proposed methods have good perfomance and stable operation through performance evaluation.