• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.1
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• pp.1-11
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• 2004

This paper presents an implementation of smart antenna system channel card that executes modulation/demodulation. Operations and performances of modules of implemented channel card is confirmed and field test of channel card shows the performance of smart antenna systems. Based on the analysis obtained from the field test in cdma2000 1x environments which contains multipath lading, it is confirmed that smart antenna system channel card provide exact beampattern to the DOA and performance of proposed channel card has better FER by 5∼8 times, compared to 2 antenna diversity system.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.2
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• pp.107-114
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• 2003

In this paper, we propose an efficient mutual authentication and key distribution protocol for cdma2000 packet data service which uses Mobile U access method with DIAMETER AAA(Authentication, Authorization and Accounting) infrastructure. The proposed scheme provides an efficient mutual authentication between MN(Mobile Node) and AAAH(home AAA server), and a secure session-key distribution among Mobile If entities. The proposed protocol improves the efficiency of DIAMETER AAA and satisfies the security requirements for authentication and key distribution protocol. Also, the key distributed by the proposed scheme can be used to generate keys for packet data security over 1xEV-DO wireless interface, in order to avoid a session hijacking attack for 1xEV-DO packet data service.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.1C
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• pp.72-80
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• 2003

This paper proposed the method of finding optimal weight vectors for enhancing the performance of an adaptive array antenna system by adopting a novel beam-forming algorithm in CDMA (code division multiple access) channel. This algorithm is a liberalized power method, based on power method, with the total computational load, O(4N). Where, N denotes the number of antenna elements. The performance of the proposed algorithm is shown in terms of SER (symbol error rates), allowable capacity, and the convergence characteristic in IS2000 1X CDMA channel. As a result of simulations, the adaptive way antenna system allows 6-10 times more users than the conventional one in a cell of a base station. Furthermore, the proposed algorithm shows superior performance to the conventional one regarding symbol error rates, converging characteristics, and computational load.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.6
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• pp.69-77
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• 2002

In this paper, we present the CDMA2000 1x compliant mobile station modem chip (SCom5010) implemented in a 0.18${\mu}{\textrm}{m}$ CMOS technology.[1] ARM940T cached processor. TeakLite DSP core, and other peripheral blocks are integrated with the baseband modem chip. Also we show novel verification methodologies and explain how this chip can be used as an emulation processor.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04d
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• pp.223-225
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• 2003

본 논문에서는 CDMA 2000 1x망에 기반한 유무선 통합망에서 무선망의 품질을 측정하기 위해 RLP NAK Rate를 사용하는 방법을 제안한다. 무선망은 유선망과 다른 특성을 가지며 무선망에 적절히 대응하는 전송 알고리즘을 적용하기 위해서는 무선망의 정확한 품질 측정이 필요하다. 이를 위해 유무선 통합망에서 유선의 영향없이 무선망의 품질만을 측정할 수 있는 RLP NAK Rate를 제안하고, 이를 통하여 무선망의 품질을 확인할 수 있음을 실험을 통해 밝힌다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.11
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• pp.1134-1142
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• 2003

This paper presents a hardware implementation of the STS diversity system, utilizing FPGAs and introduces the function and the design method of each of the modules of the system. In order to improve the performance of the implemented STS system which is an open loop transmit diversity system under fading environment, the exact estimation of the communication channel is essential. Therefore, we propose the optimal forgetting factor to estimate pilot channel in this paper, It is shown in this paper that the pilot channel is estimated using the forgetting factor of 0.7 without increasing the integration range of the pilot channel even when the power of pilot channel is not sufficiently large in CDMA 2000 1x signal environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.9A
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• pp.891-899
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• 2008

The cdma2000 1xEV-DO system controls the data rates of mobile terminals based on a binary overload indicator from the base station and a simple probabilistic model. However, this traffic control scheme has difficulty in controlling the reverse-link traffic load effectively and in guaranteeing a stable operation of the reverse link because each mobile terminal determines the next data rate autonomously. This paper proposes a new trafRc control scheme to improve the system stability, and analyzes the proposed scheme by modeling it as a discrete-time Markov process. The numerical results show that the maximum data rate of the proposed scheme is much higher than that of the conventional one. Moreover, the proposed scheme does not modify the standard physical channel structure, so it is compatible to the existing 1xEV-DO system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.11B
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• pp.920-929
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• 2004

Nowadays, wireless packet data services are provided over cdma2000 1x/1xEV-DO mobile communication network and Portable Internet are being standardized for users demanding higher data rate services. Portable Internet can provide high data rate services, but its service coverage is relatively small. If Portable Internet may be integrated with cdma2000 mobile networks, users are able to choose the best service according to service areas and get seamless services while they are moving around. At the same time, it is cost-effective for operators to construct and maintain the integrated network. For the purpose of effectively integrating Portable Internet into cdma2000 networks, we propose an integration scheme including network architecture, protocol architecture, functions in network elements, interfaces between them, and call-flow procedures. The integration scheme proposed in this paper adopts a tightly-coupled architecture for unified authentication/accounting and seamless services. In addition, the scheme can be implemented without modifying the existing cdma2000 mobile communication networks. It is also simple to develop the dual-mode mobile station. Through the simulation results based on the performance model for handoffs between cdma2000 and Portable Internet, it has teen validated that the proposed scheme diminishes packet losses compared with the loosely-coupled architecture.

• Information and Communications Magazine
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• v.21 no.7
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• pp.156-167
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• 2004

이동통신은 아날로그 음성을 전달하는1세대의 아날로그 이동 전화로부터 시작하여 2세대의 디지털 이동통신에서는 디지털 음성 전화 및 단문서비스를 제공하였으며, 3세대 이동통신시스템인 IMT-2000(International Mobile Telecommunications-2000)으로는 동기 방식 cdma2000과 비동기 방식의 W-CDMA에서는 2Mbps급 이상의 데이터 서비스를 제공한다. 현재 서비스 중이거나 계획 중인 WCDMA, cdma2000 1x,cdma2000 1x EVDO와 EVDV는 이동 멀티미디어 서비스의 제공을 목표로 설계되었으나, 현재 이들 3세대 시스템은 2세대 시스템에 비하여 기술적으로 진보된 개념들을 도입하였음에도 불구하고, 서비스 제공 관점에서 2세대 시스템과의 차별화에 성공적으로 대처하지 못하고 있고, 2세대 시스템이 이동전화 서비스를 제공하는데 있어 용량 부족의 문제가 없으므로 사업자들이 신규 투자에 매우 소극적인 상황이다.(중략)

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2A
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• pp.147-156
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• 2004

This paper presents an implementation and performance analysis of an access channel decoder which exploits a diversity gain due to the independent magnitude of received signals energy at each of antenna elements of a smart antenna BTS (Base-station Transceiver Subsystem) operating in CDMA2000 1X signal environment. Proposed access channel decoder consists of a searcher supporting 4 fingers, Walsh demodulator, and demodulator controller. They have been implemented with 5 of 1 million-gate FPGA's (Field Programmable Gate Array) Altera's APEX EP20K1000EBC652 and TMS320C6203 DSP (digital signal processing). The objective of the proposed access channel decoders is to enhance the data retrieval at co]1-site during the access period, for which the optimal weight vector of the smart antenna BTS is not available. Through experimental tests, we confirmed that the proposed access channel decoder exploitng the diversity technique outperforms the conventional one, which is based on a single antenna channel, in terms of detection probability of access probe, access channel failure probability, and $E_{b/}$ $N_{o}$ in Walsh demodulator.r.r.