• Journal of Internet Computing and Services
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• v.7 no.1
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• pp.173-178
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• 2006

In this paper, a channel estimation based on the time-domain windowing and its imperfectness in OFDM-based multiple-antenna transmission systems are analyzed with an emphasis on a preamble design for multi-channel separation, From the computer simulation results, the OFDM-CDMA system applying a space-time-frequency diversity with a full-rate full diversity code can give the diversity of D = 4 and D = 8 for both multi-user cases of maximum user and half user capacities, respectively

• ETRI Journal
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• v.26 no.2
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• pp.185-188
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• 2004

In this paper, we design a two-step scheduling algorithm to support multiple bandwidth allocation policies for upstream channel access in an Ethernet passive optical network. The proposed scheduling algorithm allows us a simultaneous approach for multiple access control policies: static bandwidth allocation for guaranteed bandwidth service and dynamic bandwidth allocation for on-demand, dynamic traffic services. In order to reduce the scheduling complexity, we separate the process of the transmission start- time decision from the process of grant generation. This technique does not require the timing information of other bandwidth allocation modules, so respective modules are free from a heavy amount of timing information or complex processing.

• ETRI Journal
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• v.35 no.2
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• pp.234-244
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• 2013

Internet protocol television (IPTV) service depends on the network quality of service (QoS) and bandwidth of the broadband service provider. IEEE 802.16j mobile multihop relay Worldwide Interoperability for Microwave Access networks have the opportunity to offer high bandwidth capacity by introducing relay stations. However, to actually satisfy QoS requirements for offering IPTV services (HDTV, SDTV, Web TV, and mobile TV) for heterogeneous users' requests, providers must use a video server for each IPTV service type, which increases the network load, especially bandwidth consumption and forwarding time. In this paper, we present a solution for forwarding IPTV video streaming to diverse subscribers via an 802.16j broadband wireless access network. In particular, we propose a new multicast tree construction and aggregation mechanism based on the unique property of prime numbers. Performance evaluation results show that the proposed scheme reduces both bandwidth consumption and forwarding time.

• Proceedings of the IEEK Conference
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• summer
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• pp.176-180
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• 2004

In this paper we introduce a bandwidth allocation algorithm and admission control policy for IEEE 802.16 broadband wireless access standard. The proposed mechanism is practical and compatible to the IEEE 802.16. Our scheme provides QoS support to high priority traffic and high throughput in low priority traffic. The simulation show that the proposed scheme includes QoS support for real-time traffic and we presented that BS determine a efficient contention mini-slot size. We have shown the relationship between traffic size and its QoS requirements and the network performance.

• IE interfaces
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• v.20 no.4
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• pp.427-437
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• 2007

As increasing the Internet traffic, many researches on access network are reported for end-to-end highspeed broadband network, where E-PON (Ethernet-Passive Optical Network) is one of reasonable candidates for the network with respect to cost and bandwidth utilization. For the high-speed access network, E-PON needs an efficient bandwidth allocation method. This paper describes a WFBA (Water-Filling Bandwidth Allocation) algorithm for the efficient bandwidth allocation with various simulation test. Based upon the simulation test, we suggest several ways to improve performance of E-PON.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6B
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• pp.875-887
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• 2010

The workgroup of IEEE 802 proposed the IEEE 802.16 standard, also known as WiMAX, to provide broadband wireless access (BWA). The standard specifies two operational modes, one is popular PMP mode, and the other is optional mesh mode. In the mesh mode, the network entry process-NetEntry is the pivotal procedure for mesh network topology formulation and thus, influences the accessibility of whole mesh network. Unfortunately, the NetEntry process suffers from the hidden neighbor problem, in which new neighborship emerges after a new node comes in and results in possible collisions. In this paper, we propose a new SN-protected NetEntry process to address the problem. Simulation results show that the new proposed NetEntry process is more stable compared with the standard-based NetEntry process.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1A
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• pp.10-15
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• 2010

This paper proposes a practical method for AGC (Automatic Gain Control) in WiBro (Wireless Broadband) AT (Access Terminal) system. Downlink packets in this system consist of preamble symbols for AGC, AFC (Automatic Frequency Control) and other purposes and data symbols for traffic transmission. In this paper we compare theoretical BER (Bit Error Rate) performance with simulation results and produce optimum parameters for AGC in this system. And we propose an efficient AGC scheme before synchronization.

• Journal of Information Science Theory and Practice
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• v.12 no.1
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• pp.60-76
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• 2024

Broadband Internet has proven to be vital for economic growth in developed countries. Developing countries have implemented several initiatives to increase their broadband access. However, its full potential can only be realized through adoption and use. With lower-middle-income countries accounting for the majority of the world's unconnected population, this study employs the theory of planned behavior (TPB) to investigate users' intentions to adopt broadband. Rural Tanzania was chosen as a case study. A cross-sectional study was conducted over three weeks, using 155 people from seven villages with the lowest broadband adoption rates. Non-probability voluntary response sampling was used to recruit the participants. Using the TPB constructs: attitude toward behavior (ATB), subjective norms (SN), and perceived behavioral control (PBC), ordinal regression analysis was employed to predict intention. Descriptive statistical analysis yielded mean scores (standard deviation) as 3.59 (0.46) for ATB, 3.34 (0.40) for SN, 3.75 (0.29) for PBC, and 4.12 (0.66) for intention. The model adequately described the data based on a comparison of the model with predictors and the null model, which revealed a substantial improvement in fit (p<0.05). Moreover, the predictors accounted for 50.3% of the variation in the intention to use broadband Internet, demonstrating the predictive power of the TPB constructs. Furthermore, the TPB constructs were all significant positive predictors of intention: ATB (β=1.938, p<0.05), SN (β=2.144, p<0.05), and PBC (β=1.437, p=0.013). The findings of this study provide insight into how behavioral factors influence the likelihood of individuals adopting broadband Internet and could guide interventions through policies meant to promote broadband adoption.

• TTA Journal
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• s.100
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• pp.51-57
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• 2005

차세대 이동통신 표준화는 크게 네가지 분야에서 진행되고 있다. 3GPP, 3GPP2에서의 3G Evolution, IEEE 802.16에서의 Broadband Wireless Access, OMA에서의 응용서비스의 표준화, 그리고 ITU-R에서의 Spectrum 및 Beyond 3G 비전 연구 등이다. 본 고에서는 현 시점에서 각 기구에서 진행되고 있는 표준활동의 개요를 간단히 소개한다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.6 s.336
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• pp.33-40
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• 2005

In this paper, we analyzed the DRMA(Dynamic Reservation Multiple Access) protocol with Rayleigh fading, shadowing, and capture effect for the Broadband fireless Access System. We consider the TDMA-based protocols, since these are based on the standard for IEEE 802.16 WMAN, IEEE 802.20 MBWA, and ETSI HIPERLAN//2. The results of analytical model will be apply the development of collision resolution algorithm, scheduling algorithm and the dynamic change of system parameters.