• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4A
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• pp.414-422
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• 2011

This paper describes a design of low-density parity-check(LDPC) decoder supporting block length 2,304-bit and code rate 1/2 of IEEE 802.16e mobile WiMAX standard. The designed LDPC decoder employs the min-sum algorithm and partially parallel layered-decoding architecture which processes a sub-matrix of $96{\times}96$ in parallel. By exploiting the properties of the min-sum algorithm, a new memory reduction technique is proposed, which reduces check node memory by 46% compared to conventional method. Functional verification results show that it has average bit-error-rate(BER) of $4.34{\times}10^{-5}$ for AWGN channel with Fb/No=2.1dB. Our LDPC decoder synthesized with a $0.18{\mu}m$ CMOS cell library has 174,181 gates and 52,992 bits memory, and the estimated throughput is about 417 Mbps at 100-MHz@l.8-V.

• Journal of Advanced Navigation Technology
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• v.13 no.6
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• pp.916-925
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• 2009

4S (Ship to Ship, Ship to Shore) communication is the key to strategic development of e-navigation, a core element of IT vessel convergence. 4S communication is intended to integrate and standardize various communication infrastructures on land and communication equipment complying with communication equipment equipped in ships. This paper aims to apply the Korean technology IEEE 802.16e adopted as an international standard, to replace and compensate for existing vessel communication media such as low speed HF/MF/VHF to the ocean environment. To this end, various experimental conditions between the coast station where a relay station was installed and related equipment equipped on a ship are set. Communication signals were monitored and the RSSI and CINR were measured. Based on experimental analysis and results, various challenges and solutions which may occur in ocean environment were sought, and communication availability was analyzed through transmission data throughput, at the maximum effective distance range of the signal. It was proven that high speed multimedia data could be exchanged for up to 20 km even among 80km kph ships moving around near the sea, ensuring that this technology could be applied to the ocean environment.

• The KIPS Transactions:PartC
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• v.14C no.6
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• pp.503-508
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• 2007

Since the Wibro service realize mobile network on the public, it has been considered that it is not enough to support real time service at vehicular speed. The standard Fast Mobile IPv6 Handover Protocol using HMIPv6 may guarantee seamless service as long as the Mobile Node moves in the same domain MAP however it does not regard fast handover over inter-MAP domain. Thus Macro Mobility Handover in HMIPv6 was proposed to reduce handover latency in inter-MAP domain. But it is still not enough to support real-time service. So we propose an Improved FHMIPv6 over 802.16e network to reduce the overall handover latency. We embedded Layer 3 handover messages of the FHMIPv6 into the Layer 2 handover messages. So the MN is able to $^-nish$ overall handover procedure earlier in our scheme. The numerical results show the performance of IFHMIPv6 has improved about 32% in comparison with FHMIPv6.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.10
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• pp.2247-2253
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• 2010

WiBro(Wireless Broadband Internet) is the standard of high-speed portable internet based on OFDMA/TDD (Orthogonal frequency division multiple access / Time division duplexing) techniques, and the subset of consolidated version of IEEE802.16e Wireless MAN standard. In this paper, we propose performance improvements of WiBro system using the LVQ(Learning Vector Quantization) blind equalization. Proposed method used the prefiltering LVQ neural network blind equalization in the Broadband WiBro system receiver. The prefiltering LVQ neural network constellates 16QAM that is transmitter data shape and the blind equalization removes ICI(Inter Carrier Interference). To verificate the proposed method usability, the MSE(Mean Square Error) and the BER(Bit Error Rate) are simulated. The simulation results shown that is improved the performances of the proposed WiBro system using the LVQ blind equalization than the existing WiBro system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.9
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• pp.1638-1645
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• 2008

WiBro(Wireless Broadband Internet) is the standard of high-speed portable internet based on OFDMA/TDD techniques, and the subset of consolidated version of IEEE802.16e Wireless MAN standard. In this paper, we propose the design method of WiBro system using the SOFM Blind Equalization. Proposed design method used SOFM neural network blind equalization with Bussgang algorithms in the Broadband 16 QAM WiBro system receiver. To verificate the proposed design method usability, the MSE and the BER are simulated. The simulation results shown that is improved the equalization performances of the proposed WiBro system using the SOFM Blind equalization than the existing WiBro system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.5
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• pp.1125-1132
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• 2010

WiBro(Wireless Broadband Internet) is the standard of high-speed portable internet based on OFDMA/TDD (Orthogonal frequency division multiple access / Time division duplexing) techniques, and the subset of consolidated version of IEEE802.16e Wireless MAN standard. In this paper, we propose performance improvements of WiBro system using the 64QAM SOFM(Self-Organizing Feature Maps)prefiltering. Proposed method used the prefiltering SOFM neural network blind equalization in the Broadband 64 QAM WiBro system receiver. The prefiltering SOFM neural network constellates 64QAM that is transmitter data shape and the blind equalization removes ICI(Inter Carrier Interference). To verificate the proposed method usability, the MSE and the BER are simulated. The simulation results shown that is improved the performances of the proposed WiBro system using the 64QAM SOFM Prefiltering than the existing WiBro system.

• Journal of Advanced Navigation Technology
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• v.18 no.2
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• pp.142-150
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• 2014

In this paper, the performance analysis results of time/frequency synchronization and cell search algorithm are presented for aeronautical mobile airport communication systems (AeroMACS). AeroMACS is based on IEEE 802.16e mobile WiMAX standard and uses the aeronautical frequency band of 5GHz with the bandwidth of 5MHz. The simulation model of AeroMACS is designed and the performance evaluation is conducted with the various airport channel models such as apron (APR), runway (RWY), taxiway (TWY), and park (PRK). The proposed synchronization unit was designed in hardware description language (HDL) and implemented on FPGA. Also, the real-time operation was verified and evaluated using FPGA test system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.10
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• pp.1786-1795
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• 2006

Portable Internet extended from wireless LAN has a large cell size, similar to a wireless mobile communication. and can provide the seamless service which offers middle-low speed mobility. IEEE 802.16e, the international standard of Portable Internet, uses PKMv2 protocol for authorization and key exchange between a MSS and a BS. This paper proposes a new protocol based on PKMv2, which can provide that MSS is able to do fast authorization with a new BS when soft handover is occurred in a MSS. Our protocol can carry out fast authorization because of reducing the number of messages and parameter exchange, public key encryption and signature in wireless network more than the previous works. It also prevents eavesdropping from an external attacker and keeps the security against impersonation attacks for both a MSS and a BS.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.4
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• pp.921-929
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• 2011

This paper describes an analysis of the decoding performance and decoding convergence speed of layered LDPC(low-density parity-check) decoder for mobile WiMAX system, and the optimal design conditions for hardware implementation are searched. A fixed-point model of LDPC decoder, which is based on the min-sum algorithm and layered decoding scheme, is implemented and simulated using Matlab model. Through fixed-point simulations for the block lengths of 576, 1440, 2304 bits and the code rates of 1/2, 2/3A, 2/3B, 3/4A, 3/4B, 5/6 specified in the IEEE 802.16e standard, the effect of internal bit-width, block length and code rate on the decoding performance are analyzed. Simulation results show that fixed-point bit-width larger than 8 bits with integer part of 5 bits should be used for acceptable decoding performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.771-774
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• 2010

In this paper, BER performance of LDPC(Low-Density Parity-Check) decoder for WiMAX is analyzed, and optimal design conditions of LDPC decoder are derived. The min-sum LDPC decoding algorithm which is based on an approximation of LLR sum-product algorithm is modeled and simulated by Matlab, and it is analyzed that the effects of LLR approximation bit-width and maximum iteration cycles on the bit error rate(BER) performance of LDCP decoder. The parity check matrix for IEEE 802.16e standard which has block length of 2304 and code rate of 1/2 is used, and AWGN channel with QPSK modulation is assumed. The simulation results show that optimal BER performance is achieved for 7 iteration cycles and LLR bit-width of (8,6).