Yong-Hoon Cho

Efficient bit-interleaved APSK scheme for LDPC codes

This paper presents a new bit-interleaved higher-order APSK scheme for LDPC codes. Although the maximum decoding performance can be achieved using the maximum likelihood (ML) soft detection scheme, the complexity increases exponentially with the modulation orders. We approximate the ML soft detection scheme by applying the hard decision threshold (HDT) based method for a modified constellation of 32-APSK. In order to further improve the BER performance, we combined an efficient bit interleaving scheme, by considering that BER performance of each bit contained in a symbol is not uniform. Simulation results demonstrate that the proposed bit-interleaved scheme with very simple HDT based soft detection can achieve better performance compared to the ML detection of conventional scheme.

Soft decoding for raptor codes with an efficient early termination algorithm

We propose an efficient soft iterative decoding scheme with early termination algorithm for raptor codes. In the proposed scheme, the performance is enhanced by adopting iterative decoding, both in each inner and outer code and in the concatenated code itself between the inner and outer codes. At the same time, the complexity is reduced by applying an efficient early termination algorithm. Simulation results show that our proposed method can achieve a large amount of complexity reduction without any performance degradation.

Development of sensor network nodes for ultrasonic sensor-driven position system inside buildings

Ubiquitous location-based services (u-LBS) that can detect the location of objects or people anytime and anywhere and use this as a basis for providing useful services are emerging important services. Location tracking services are applicable in a wide variety of fields such as logistics, security, industrial autonomy, wireless sensor networks and military tracking. There are various location detection systems using different methods such as infrared, ultrasonic, RFID, UWB and signal strength. This thesis will examine the performance and practical uses of ultrasonic location detection nodes

Development of a Integrated RF Module for the Terrestrial and the Satellite DMB(Digital Multimedia Broadcasting) Services

The mobile video, audio and data services can be provided by a DMB (digital multimedia broadcasting) system based on Eureka-147 standard in Korea. In Korea the S-DMB and the T-DMB use the different systems each other. For the both of the satellite and the terrestrial DMB services using the same platform, an integrated RF module is required. In this paper -we show the design of an integrated RF tuner module which includes a L-band down-converter and a band III tuner and a S-DMB tuner, and show the measured results of an integrated RF module for T-DMB that give an IF output of 38.912 MHz and a VCO of 220.32 MHz to 282.72 MHz with PLL setup

Aspects of interleaving for turbo codes

In this letter, we present some aspects of bit interleaving schemes applicable for turbo codes with block and convolutional codes as their component codes. A bit interleaving scheme across inter-codewords can be used to increase the performance of the codes when a block of correlated channel information exits in a codeword. We present an efficient bit interleaving scheme that can maximize the time diversity of the codeword, especially for block turbo codes.

An efficient parallelization of MAP decoding for double binary turbo codes

Excellent performance of turbo codes approximating to the Shannon limit should be conditioned on a large codeword length which inherently requires very long trellis. There have been a number of parallel decoding algorithms in order to accelerate the decoding speed. In these algorithms, the long trellis was partitioned into a number of shorter sub-trellises so that the the parallel search along the partitioned the sub-trellises can be performed. This trellis partition usually show performance degradation. In this paper, we propose an efficient parallel decoding algorithm for double binary turbo codes. The simulation results investigated in this paper reveal that the proposed scheme speed up the decoding time almost 4 times compared to the conventional full trellis searching method with negligible performance degradation, for various code rates and codeword lengths.

Block Turbo Codes for High Order Modulation and Transmission Over a Fast Fading Environment

A forward error correction (FEC) coding techniques is one of time diversity techniques with which the effect of channel impairments due to noise and fading are spreaded over independently, and thus the performance could be improved. Therefore, the performance of the FEC scheme can be maximized if we minimize the correlation of channel information across over a codeword. In this paper, we propose a block turbo code with the maximized time diversity effect which may be reduced due to utilization of high order modulation schemes and due to transmission over a comparatively fast fading environment. Especially, we propose a very simple formula to calculate the address of coded bit allocation, and thus we do not need any additional outer interleavers, i.e., inter-codeword interleavers. The simulation resuts investigated in this paper reveal that the proposed scheme can provide the performance gain of more than a few decibels compared to the conventional schemes.