• ETRI Journal
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• v.25 no.5
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• pp.418-421
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• 2003

We propose an unbiased signal-to-interference ratio (SIR) estimator for the high speed downlink packet access (HSDPA) system. The proposed SIR estimator solves the problem of underestimation present in conventional SIR estimators and is suitable for channel quality measurement in the adaptive modulation and coding scheme of HSDPA, which requires accurate SIR estimation for optimum adaptive modulation and coding selection. Our analysis and simulation results demonstrate the improved estimation performance of the proposed SIR estimator.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.1
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• pp.37-44
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• 2011

HSPA(High Speed Packet Access)/HSPA+ is a combined 3GPP(Third Generation Partnership Project) standard of HSDPA(High Speed Downlink Packet Access) and HSUPA(High Speed Uplink Packet Access). The standard can provide the high speed multimedia service against the 3GPP release 99 standard. In order to test the 3GPP HSPA/HSPA+ terminal performance, the measurement hardware is required for the evaluate the transmitted signal of HSPA/HSPA+ terminals. Agilent Technologies and Innowireless produce the measurement equipments for HSPA/HSPA+ terminals. Generally speaking, the receiving algorithms in normal modems cannot be used directly to the measurement system due to the lack of the algorithm accuracy. In this paper, we propose the new receiver algorithm for precise measurement of 3GPP HSPA/HSPA+ terminal signal, and implement measurement functionality for performance measurement of the 3GPP HSPA/HSPA+ terminal by using software. The proposed 3GPP HSPA/HSPA+ signal measurement algorithm can be used for the commercial system through code execution speed optimization.

• Journal of KIISE:Information Networking
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• v.29 no.5
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• pp.466-472
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• 2002

We investigate the load sharing problem between the umbrella cell and the overlaid tells in hierarchical cell structure. A load sharing strategy is proposed and its performance is evaluated by simulation when it is used for transmission of the mobile Internet traffic using the High Speed Downlink Packet Access scheme. The results show that, with the proposed strategy, the microcell backs well the overlaid picocells up, especially when a specific picocell cluster suffers unusual heavy load condition. By using the strategy, we can reduce the installation cost, otherwise needed for increasing the system capacity of every picocell cluster to cope with the unusual heavy load.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.1
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• pp.13-22
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• 2004

This paper drives the exact expression of bit error rate(BER) performance for successive interference cancellation(SIC) algorithm against multipath interference components in a high-speed downlink packet access(HSDPA) system of W-CDMA downlink and the BER performance is evaluated by numerical analysis. Numerical results showed that the average BER performance is rapidly saturated in terms of increasing the number of multipath and is revealed significant improvement for improvement Processing gain(PG). For example, the average BER Performance of the SIC algorithm is superior to the performance of conventional scheme by more than 7dB and 1.4dB for processing gain PG=54 and 128 under the two-path channel and average BER=$1.0{\times}10^{-3}$, respectively. This results also indicated that the average BER saturation is occurred at nearly one weight factor which is assigned to pilot and data channels. Likewise, the average BER performance is greatly degraded due to increasing the interference power in proportional to the number of multipath with increasing multicode K. And the smaller multipath fading channel gain is arrived later, the more the average BER performance is improved. The results of performance analysis in this paper indicated that the multipath interference cancellation is required to improve the BER performance in a HSDPA system under multicode for high-speed packet transmission, low spreading factor, and multipath fading channel.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1A
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• pp.16-24
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• 2010

High Speed Uplink Packet Access(HSUPA) is a WCDMA Release 6 technology which corresponds to High Speed Downlink Packet Access(HSDPA). Node B Supports fast scheduling, Hybrid ARQ(HARQ), short Transmission Time Interval(TTI) for high rate uplink packet data. It is very important to detect Iub congestion to improve end user's Quality of Service(QoS). This paper proposes Node B Congestion Detection(BCD) mechanism and suggests to use the hybrid of Transport Network Layer(TNL) congestion detection and BCD. It is shown that HSUPA user throughput performance can be improved by the proposed method even with small Iub bandwidth.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.510-510
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• 2006

• The KIPS Transactions:PartC
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• v.19C no.2
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• pp.119-126
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• 2012

This paper covers the service quality of packet-based voice service that is provided over wireless broadband (WiBro) and high speed downlink packet access (HSDPA) systems. Using a measurement software that has been developed in the course of preparing a advanced service quality management scheme for the packet-based voice service over wireless networks, a huge scale of experiment is conducted to measure the real quality of the voice service. Based on our analysis of the measurement results, the service quality of the voice service is supposed to be quite good over both wireless systems. In addition, another experiment to investigate the effect of degradation of wireless transmission conditions on the service quality of the voice service shows the values of wireless service metrics in which mean opinion score (MOS) starts to decrease.

• Journal of Communications and Networks
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• v.14 no.3
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• pp.273-279
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• 2012

In this paper, we propose an iterative interstream interference cancellation technique for system with frequency selective multiple-input multiple-output (MIMO) channel. Our method is inspired by the fact that the cancellation of the interstream interference can be regarded as a reduction in the magnitude of the interfering channel. We show that, as iteration goes on, the channel experienced by the equalizer gets close to the single input multiple output (SIMO) channel and, therefore, the proposed SIMO-like equalizer achieves improved equalization performance in terms of normalized mean square error. From simulations on downlink communications of $2{\times}2$ MIMO systems in high speed packet access universal mobile telecommunications system standard, we show that the proposed method provides substantial performance gain over the conventional receiver algorithms.

• Journal of Communications and Networks
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• v.11 no.5
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• pp.464-472
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• 2009

In this paper, we propose a packet scheduling algorithm for cellular relay networks by considering relay selection, variation of channel quality, and packet delay. In the networks, mobile users are equipped with not only cellular but also user relaying radio interfaces, where base station exploits adaptive high speed downlink channel. Our proposed algorithm selects a user with good cellular channel condition as a relay station for other users with bad cellular channel condition but can get access to relay link with good quality. This can achieve flexible packet scheduling by adjusting transmission rates of cellular link. Packets are scheduled for transmission depending on scheduling indexes which are calculated based on user's achieved transmission rate, packet utility, and proportional fairness of their throughput. The performance results obtained by using computer simulation show that the proposed scheduling algorithm is able to achieve high network capacity, low packet loss, and good fairness in terms of received throughput of mobile users.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.10A
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• pp.896-905
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• 2005

In this paper, we propose a SPD(Selective Packet Delay) scheme to improve the performance of High-Speed Downlink Shared Channel(HS-DSCH) employing N-Channel Stop and Wait retransmission scheme in High Speed Downlink Packet Access(HSDPA) system. The proposed SPD coordinates packet transmissions according to the channel condition. When the channel condition is bad, packet transmission is forcedly delayed, and the designated time slot is set over to other users in good channel condition. Hence, the SPD is able to reduce the average transmission delay for packet transmission under the burst error environments. In addition, we propose two packet scheduling schemes called SPD-LDPF(Long Delayed Packet First) and SPD-DCRR(Deficit Compensated Round Robin) that are effectively combined with the SPD scheme. Simulation results show that the proposed scheme has better performance in terms of delay, throughput and fairness.