• The Journal of the Korea Contents Association
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• v.9 no.2
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• pp.60-66
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• 2009

In this paper, implementation of an ensemble transport interface (ETI) adapter for multimedia services based on terrestrial-digital multimedia broadcasting (T-DMB) is introduced. In general, ETI adapter should manipulate three functions: receiving packets packing multimedia data from service providers, configuring an ETI frame (G.703) from these data, and transmitting these frames to T-DMB multiplexer. To achieve these roles, the proposed ETI adapter consists of the network management module for data transmission and flow control between service providers and this adapter, the ETI configuration module for gathering data and then making ETI frames, and the hardware board for pushing ETI frames in real-time. The proposed adapter yielded faithful results without data lose on transmitting ETI frames to T-DMB multiplexer in the range of $64{\sim}1,153kbps$ specified in ETSI EN 300 401 after packing multimedia data received via Internet.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.12
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• pp.1638-1643
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• 2019

In this paper, we propose an adaptive-perturbation-aided opportunistic precoding (APOP) scheme for multiple-input multiple-output (MIMO) systems. To update a precoding matrix in MIMO systems, the proposed algorithm produces a random perturbation in each time slot. Then the additional adaptive perturbation is also applied, which depends on the reports of achievable data-rates from users. If the prior random perturbation increased the data rate, the adaptive perturbation is set to be the same as the prior random perturbation, otherwise the negative value of the prior random perturbation is applied for adaptive perturbation. Furthermore, to enhance the achievable data rates, the information on the stored precoding matrices in the memory as well as the currently generated precoding matrix is used for scheduling. Simulation results show that compared to conventional opportunistic precoding schemes, higher data rates are achieved by the proposed APOP scheme, especially when there are a relatively small number of users.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.9
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• pp.753-761
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• 2012

In this paper, we study a power allocation technique for Tomlinson-Harashima precoding (THP) in multi-user multiple input single output (MISO) downlink systems. In contrast to previous approaches, a mutual information based method is exploited for maximizing the sum rate of zero-forcing THP systems. Then, we propose a simple power allocation algorithm which assigns proper power level for modulo operated users. Simulation results show that the proposed scheme outperforms a conventional water-filling method, and it provides similar performance with near optimal method with much reduced complexity.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.3
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• pp.430-435
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• 2022

In this paper, we consider the non-orthogonal multiple access (NOMA) technique in the heterogeneous network (HetNET) consisting of a single macro base station (BS) and multiple small BSs, where the perfect successive interference cancellation is assumed for the NOMA signals. In this paper, we propose a deep learning-based user association and power allocation scheme to maximize the data rate in the NOMA-based HetNET. In particular, the proposed scheme includes the deep neural network (DNN)-based user association process for load balancing and the DNN-based power allocation process for data-rate maximization. Through the simulation assuming path loss and Rayleigh fading channels between BSs and users, the performance of the proposed scheme is evaluated, and it is compared with the conventional maximum signal-to-interference-plus-noise ratio (Max-SINR) scheme. Through the performance comparison, we show that the proposed scheme provides better sum rate performance than the conventional Max-SINR scheme.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.1
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• pp.59-65
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• 2008

In this paper, a new adaptive resource allocation scheme is proposed in orthogonal frequency-division multiple access(OFDMA) systems with rate proportionality constraints. The problem of maximizing the overall system capacity with constraints on bit error rate, total transmission power and rate-proportionality for user requiring different classes of service is formulated. Since the optimal solution to the constrained fairness problem is extremely complex to obtain, a low-complexity suboptimal algorithm that separates subchannel allocation and power allocation is proposed. Firstly, the number of subchannels to be assigned to each user is determined based on the users' average signal-to-noise ratio and rate-proportion. Subchannels are subsequently distributed according to the modified max-min criterion. Lastly, based on the subchannel allocation, the optimal power allocation by solving the Language dual problem is proposed. Additionally, in order to reduce the computational complexity, iterative rate proportionality tracking algorithm is proposed for maximizing the capacity together with maintaining the rate proportionality constraint.

• Journal of Internet Computing and Services
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• v.7 no.3
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• pp.41-51
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• 2006

In the case of CDMA-based packet data systems such as 1xEV-DO which are designed to support high rate services, BSs transmit data packets with a maximum power based on time multiplexing mode such that only one user can be serviced at a time. In this paper, we propose a joint power allocation and scheduling algorithm for 1xEV-DO-like systems in which we adopt a code division multiplexing (CDM) transmission method in the downlink common channel in order to utilize channel orthogonality such that we can serve more than one user at a time slot especially when there exist remaining resources after serving the firstly selected user by the scheduler. Simulation results demonstrate that the proposed scheme can improve the performances of conventional schemes such as the maximum rate and the proportional fair algorithms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.4
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• pp.633-638
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• 1994

Asynchronous Transfer Model(ATM) has a fixed-length packet transport scheme. It is one of promising proposals in Broadband ISDN(B-ISDN). Since the packet length is fixed, it can be potentially to perform the various service to user. In this paper, a queueing model for an ATM Multiplexer loaded by the Continuous Bit Rate(CBR) traffic and the bursty traffic sources is analyzed. The queueing system has a finite buffer size. The cell loss probabilities with the simple and recurcive form for a performance measures of ATM multiplexer are derived, and are also evaluated through numerical examples. The results of this study may be used as guidelines in buffer design problems and performance analysis of ATM multiplexing system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.6
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• pp.1060-1067
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• 2004

In a CDMA system, the rapacity is variable and mainly depends on multiple access interference. The multiple access interference has a deep relationship with transmitted or received power. The capacity of CDMA2000 1x system is considered to be limited by the forward link capacity. In this paper, we show that the transmitted power can represent the total cell load and we propose a load control scheme for CDMA2000 1x system. CDMA2000 1x system has fast power control scheme and we can measure forward link cell load by using total transmitted power. In the proposed algorithm, by monitoring the total transmit power, we can simply adjust data rate to channel conditions and efficiently use radio resources. The proposed algorithm is practical algorithm to implement in the power controlled CDMA systems and enhances the system throughput and quality of service(QoS)

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.06a
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• pp.219-220
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• 2013

무선통신에서 다중안테나를 사용하지 않고 다이버시티 이득을 얻기 위한 대안으로 협력 통신 기법이 개발되어 왔다. 하지만 대부분의 협력기법들은 릴레이에 신호를 전송하는 과정에서 delay 가 발생하게 되어 전송률이 감소하는 단점이 있다. 본 논문에서는 OFDMA 시스템에서 feedback 정보를 이용하는 기법을 사용하여 전송 손실이 발생하지 않으면서 기존의 MISO(multi input multi output)시스템과 비슷한 성능을 갖는 새로운 협력모델을 제안한다. 제안된 기법은 bit error rate(BER) 관점에서 평가되고 협력하는 사용자와의 채널이 보장되면 기존의 MISO 기법과 비슷한 성능을 보이는 것을 보여준다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.06a
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• pp.122-125
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• 2014

세계적으로 아날로그 방송에서 디지털 방송으로의 전환이 마무리되고 있는 가운데, 앞으로 다가올 UHDTV 등 실감의 대용량 방송 및 방송 통신 융합 환경에 대비하기 위한 새로운 차기 방송 표준에 관한 연구의 필요성이 날로 높아져 가고 있다. 특히, 저해상도 서비스에 머물러 있던 이동 방송에서는 기존 HD급의 서비스 제공이 가능한 이동 실감방송으로 진화하기 때문에 고정/이동 방송 서비스가 동시에 가능한 고효율 전송 원천 기술 개발이 이루어질 필요가 있다. 이에 최근 지상파 단일 채널을 통해 4K & HD 방송 서비스를 동시에 제공하는 융합방송 시스템 개발에 대해서 연구가 진행되고 있다. 본 논문에서는 지상파 단일 채널을 통해 4K & HD 융합방송 서비스를 제공하기 위해 필요한 전송 요구 사항들에 대해서 분석하고, 효율적인 데이터 전송을 위해 필요한 전송 시스템 및 다중화 기술에 관해서 알아보았다. 또한 분석한 데이터 전송률을 달성하기 위한 최적의 시스템 파라메터를 도출하고 분석하였다.