• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.11
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• pp.67-72
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• 2004

In this paper, we propose a downlink beamforming method which is considered common pilot channel for coherent detection and dedicated traffic channel for desired user in FDD/CDMA systems. The existing downlink beamforming system produces phase mismatch between traffic and pilot signals at desired mobile as well as interference to other mobiles. A new downlink beamforming method can solve above problem based on least squares method between reference function and beamforming function. A numerical analysis shows that the proposed downlink beamforming method matches well and gives low BER performance.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.7
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• pp.21-30
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• 2004

The capacity of WCDMA TDD system is limited mainly by the interference. So, to achieve the expected performance of WCDMA TDD system and to minimize the interference to cdma2000 system interferences, such as interference within WCDMA TDD system inter-cell interference, and interferences between cdma2000 systems, should be considered carefully. In this paper, by using System-level Simulation, we analyzed the interferences between WCDMA TDD system and cdma2000 system in practical situation based on the exact parameters of 3GPP TR 25.942 and by using System-level Simulation considering Link-level we analyze the interferences between WCDMA TDD system and cdam2000 system. From Simulation Results, we propose the condition for optimizing system capacity considering the interferences between WCDMA TDD system ＆ cdam2000 system

• Journal of Communications and Networks
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• v.2 no.1
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• pp.46-57
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• 2000

Ongoing standardization effort on 3G cellular system in 3GPP (UNTS) is based on GPRS core network and promises a global standard for systems capable of offering ubiquitous access to internet for mobile users. Considered radio access systems(FDD CDMA, TDD CDMA, and EDGE) are optimized for robust mobile use. However, there are alternative relatively high-rate radio interfaces being standardized for WLAN (IEEE802.11 and HIPER-LAN/2) which are capable of delivering significantly higher data rates to static or semi-static terminals with much less overhead. Also WPANs(BLUETOOTH, IEEE802.15), which will be present in virtually every mobile handset in the near future, are offering low cast and considerable access data rate and thus are very attractive for interworking scenarios. The prospect of using these interfaces as alternative RANs inthe modular UMTS architecture is very promising. Additionally, the recent inclusion of M-IP in the UMTS R99 standard opens the way for IP-level interfacing to the core network. This article offers an overview into WLAN-Cellular interworking. A brief overview of GPRS, UMTS cellular architectures and relevant WLAN standards is given. Possible interworking architectures are presented.