• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.298-307
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• 2002

This paper concentrates on developing and analyzing an advanced space-time multiuser receiver for WCDMA forward link. Through exploring the interference caused by co-channel users and delayed multipaths in CDMA, a constrained linear adaptive filter is adopted to cancel the interference. Furthermore, by utilizing the space-time diversity, an optimum diversity receiver, called a constrained adaptive space-time interference canceller (C-ASTIC), is proposed. For comparison, the statistical analysis of multiuser performance for WCDMA system with space-time diversity is described. The result of the simulation showed that C-ASTIC performs better than both the space-time diversity combining maximal ratio combiner (MRC) and the single-antenna adaptive interference canceller in a multipath fading channel. Also, the efficiency of the C-ASTIC in the multimedia communication environment is investigated under the multiuser, multi-transmit antenna, and multirate WCDMA system in a multipath fading channel. From the results, the C-ASTIC was validated to be useful for multi-rate WCDMA system through improving the performance gain by more than 3 dB at BER of 10$\^$-3/ in a half or more loaded system.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.2
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• pp.29-34
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• 2011

In this paper, we propose antenna and relay selection system by considering channel environment between nodes. Each node has multiple antennas in each hop. And, we analyze the performance of proposed system. A General MIMO system receives signals through multiple channels and obtains diversity gain. But MIMO system causes performance degradation due to poor received signals. The proposed system consider transmitters-relays channels, relays-receivers channels and select a best channel. This channel selection prevents performance degradation and increase total system's performance. Therefore, we must select best antennas and a best relay, simultaneously.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.5
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• pp.113-119
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• 2010

In this paper, the considered cognitive radio system has a pair of PT-PR and a pair of ST-SR. In first time slot(1 Phase), PT broadcast signal $x_p$ to PR, ST and SR. Then, each receivers(PR, ST, SR) decode received signal $x_p$. In second time slot(2 Phase), ST combine decoded signal ${x_p}^{\prime}$ and signal $x_s$, and it broadcast combined signal to PR and SR. PR and SR decode combined signal. At this time, PR can achieve diversity gain, due to using MRC, it combine 'received and decoded signal ${x_p}^{\prime}$ at 1 phase' and 'detected signal $x_p$ at 2 phase'. SR use linear combining technique and it can obtain $x_s$.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.5
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• pp.67-72
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• 2014

In this paper, an energy harvesting scheme is applied in the cooperative communication. The proposed scheme uses an energy harvesting relay in which the relay harvests the energy from the source node and transfers to the power form in forwarding the received data to the destination node. The well-known maximal ratio combining (MRC) technique is applied to increase the diversity gain at the destination. Therefore, with applying the proposed energy harvesting scheme, the limited power at the relay is solved, and the operation efficiency of the network and the mobile devices is improved. Finally, performance of the proposed protocol is analyzed in terms of bit error rate, outage probability, power collection efficiency.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.5
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• pp.810-816
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• 2001

This paper proposes a Truncated Type-II Hybrid ARQ scheme using an adaptive modulation system to achieve high throughput data transmission systems for mobile communication systems. In this paper, the adaptive modulation system analyzed in Nakagami (m-distribution) fading channel environment. The adaptive modulation system controls the modulation level and symbol rate according to the Nakagami fading parameter(m). When the received $E_bN_0$ is high or the Nakagami fading parameter m is high, the propose system selects higher modulation level and higher symbol rate to increase throughput. On the other hand, this system selects lower modulation level and lower symbol rate to prevent throughput performance degradation when the received $E_bN_0$ is low. The modulation method have been adopted QPSK(Quadrature Phase Shift Keying), 16 QAM(Quadrature Amplitude Modulation), 64 QAM, 256 QAM. Therefore, Adaptive Modulation Systems with Truncated Type-II Hybrid ARQ Scheme is proper for mobile and radio for mobile and radio data communication system that require high reliability and delay-limited applications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.9
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• pp.2014-2026
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• 1997

In this paper, the performances of wireless asynchronous transfer mode (ATM) cell transmission in mobile work are analyzed. We adopt 16Star QAM as amodulation technique in wireless channel and considered Reed-Solomon, convolutional, and concatenated coding to improve the error rate performances, and also proposed the Partial Concatenated Coding (PCC) technique as UEP(unequal error protection) code for efficient transmission of ATM cell in the air interface. We consider Doppler's effect, Rician fading, and diversity technique of maximal-ratio combining (MRC) for mobile channel model. For performance measure, we analyze bit error rate, ATM cell loss probability, ATM cell error probability, and network performances of ATM cell transmission delay and throughput. The numerical results show that the adoption of PCC is a prospective way for the evolution of future wireless ATM network on mobile environment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.661-667
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• 2001

This paper proposes a Truncated Type-II Hybrid ARQ scheme using an adaptive modulation system to achieve high throughput data transmission systems for DS-CDMA cellular mobile communication systems. In this paper, the adaptive modulation system analyzed in Nakagami (m-distribution) fading channel environment. The adaptive modulation system controls the modulation level and symbol rate according to the Nakagami fading parameter( m). When the received Eb/No is high or the Nakagami fading parameter m is high, the propose system selects higher modulation level and higher symbol rate to increase throughput. On the other hand, this system selects lower modulation level and lower symbol rate to prevent throughput performance degradation when the received Eb/No is low. The modulation method have been adopted QPSK 16QAM, 64QAM, 256QAM. Therefore, adaptive modulation systems with Truncated Type II Hybrid ARQ Scheme is proper for mobile and radio data communication system that require high reliability and delay-limited applications.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.1
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• pp.43-48
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• 2021

One of the effective ways to increase data transmission rate is to use massive antenna technique where tens or hundreds of antennas are deployed in base station and spatial diversity gain is improved by multiuser method. If multiuser method is applied, there will be inter-user interference and maximal ratio combiner (MRC) is conventionally used to reduce the complexity of the receiver and to eliminate interference. However, as the number of mobile devices increases, the performance of the conventional receiver becomes deteriorated. To solve this problem, we propose a new detector that completely eliminates the interference from the registered devices and reduces that from the unregistered devices. Then, to reduce the complexity of the proposed scheme, we propose adaptive algorithm of the proposed scheme. Through simulation, we show that the proposed scheme has better bit error rate performance than the conventional scheme.