http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Tho Le-Ngoc (검색결과 7 건)
- 무료
- 기관 내 무료
- 유료
-
Turbo Decoding for Precoded Systems over Multipath Fading Channels
Zhang, Qing,Le-Ngoc, THo The Korea Institute of Information and Commucation 2004 Journal of communications and networks Vol.6 No.3
A combined precoding and turbo decoding strategy for multi-path frequency-selective fading channels is presented. The precoder and multi-path fading channel are jointly modeled as a finite-state probabilistic channel to provide the multi-stage turbo decoder with its statistics information. Both a priori and a posteriori probabilities are used in the metric computation to improve the system performance. Structures of the combined turbo-encoder, interleaver, and precoder in the transmitter and two-stage turbo decoder in the receiver are described. Performance of the proposed scheme in fixed, Rician and Rayleigh multi-path fading channels are evaluated by simulation. The results indicate that the combined precoding and two-stage turbo decoding strategy provides a considerable performance improvement while maintaining the same inner structure of a conventional turbo decoder.
-
Subsidiary Maximum Likelihood Iterative Decoding Based on Extrinsic Information
Yang, Fengfan,Le-Ngoc, Tho The Korea Institute of Information and Commucation 2007 Journal of communications and networks Vol.9 No.1
This paper proposes a multimodal generalized Gaussian distribution (MGGD) to effectively model the varying statistical properties of the extrinsic information. A subsidiary maximum likelihood decoding (MLD) algorithm is subsequently developed to dynamically select the most suitable MGGD parameters to be used in the component maximum a posteriori (MAP) decoders at each decoding iteration to derive the more reliable metrics performance enhancement. Simulation results show that, for a wide range of block lengths, the proposed approach can enhance the overall turbo decoding performance for both parallel and serially concatenated codes in additive white Gaussian noise (AWGN), Rician, and Rayleigh fading channels.
-
Delay-Margin based Traffic Engineering for MPLS-DiffServ Networks
Ashour, Mohamed,Le-Ngoc, Tho The Korea Institute of Information and Commucation 2008 Journal of communications and networks Vol.10 No.3
This paper presents a delay-margin based traffic engineering (TE) approach to provide end-to-end quality of service (QoS) in multi-protocol label switching (MPLS) networks using differentiated services (DiffServ) at the link level. The TE, including delay, class, and route assignments, is formulated as a nonlinear optimization problem reflecting the inter-class and inter-link dependency introduced by DiffServ and end-to-end QoS requirements. Three algorithms are used to provide a solution to the problem: The first two, centralized offline route configuration and link-class delay assignment, operate in the convex areas of the feasible region to consecutively reduce the objective function using a per-link per-class decomposition of the objective function gradient. The third one is a heuristic that promotes/demotes connections at different links in order to deal with concave areas that may be produced by a trunk route usage of more than one class on a given link. Approximations of the three algorithms suitable for on-line distributed TE operation are also derived. Simulation is used to show that proposed approach can increase the number of users while maintaining end-to-end QoS requirements.
-
-
Delay-Margin based Traffic Engineering for MPLS-DiffServ Networks
Mohamed Ashour,Tho Le-Ngoc 한국통신학회 2008 Journal of communications and networks Vol.10 No.3
This paper presents a delay-margin based traffic engineering (TE) approach to provide end-to-end quality of service (QoS) inmulti-protocol label switching (MPLS) networks using differentiated services (DiffServ) at the link level. The TE, including delay, class, and route assignments, is formulated as a nonlinear optimization problem reflecting the inter-class and inter-link dependency introduced by DiffServ and end-to-end QoS requirements. Three algorithms are used to provide a solution to the problem: The first two, centralized offline route configuration and link-class delay assignment, operate in the convex areas of the feasible region to consecutively reduce the objective function using a per-link perclass decomposition of the objective function gradient. The third one is a heuristic that promotes/demotes connections at different links in order to deal with concave areas that may be produced by a trunk route usage of more than one class on a given link. Approximations of the three algorithms suitable for on-line distributed TE operation are also derived. Simulation is used to show that proposed approach can increase the number of users while maintaining end-to-end QoS requirements.
-
Hybrid ARQ in Multicell MU-SIMO With Large-Scale Antenna Arrays
Kim, Seong Hwan,Chaitanya, Tumula V. K.,Le-Ngoc, Tho IEEE 2016 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.15 No.9
<P>We consider hybrid automatic repeat and request (HARQ) schemes in the uplink of a multicell multiuser single-input multiple-output system with large-scale antenna arrays at the base station (BS) for improving the spectral efficiency while limiting the number of retransmissions. Assuming a zero-forcing receiver at each BS and that each BS knows only the channel gains of users in its own cell, we derive the expressions for the outage probability and long-term average transmission rate (LATR) of the Type-I HARQ, HARQ with chase-combining (HARQ-CC), and HARQ with incremental redundancy (HARQ-IR). We then formulate the optimal rateselection problems for the three schemes and provide methods to find a solution. Since the optimal-rate selection methods for the HARQ-CC and HARQ-IR schemes are computationally intensive, we propose sub-optimal rate-selection methods, which yield a closer LATR performance to that of the optimal methods. For the Type-I HARQ and HARQ-IR, we also present a parameterization-based method showing the approximate relation between the expressions of the optimized-LATR, optimal rate, and number of antennas. Illustrative results show that the HARQ-IR has significant gain over HARQ-CC and Type-I HARQ in terms of LATR, while Type-I HARQ yields practically similar performance to HARQ-CC as the number of antennas at the BS increase.</P>
-
Improving Throughput and Packet Delay of Interactive Multimedia Satellite Networks
Kun-Nyeong Chang,Ki-Dong Lee,Tho Le-Ngoc 에스케이텔레콤 (주) 2011 Telecommunications Review Vol.21 No.1
In Geostationary Earth Orbit (GEO) satellite networks, the delay of packets queued in satellite terminals in the return-link is a critical factor to degrading the quality-of-service. In this paper, we suggest two unbiased traffic forecasting models, which belong to a family of commonly used time-series models, based on the first-and secondorder variations of traffic, and develop new Demand Assignment Multiple Access (DAMA) protocols based on the proposed traffic forecasting models in order to improve the delay of packets. We compare the delay and throughput performance of the proposed DAMA protocols with that of two previous protocols under the two traffic models,SupFRP and PowON_PowOFF models, for various parameters setups. Simulation results show that the proposed protocols significantly improve the delay compared to previous DAMA protocols. This implies that, in the proposed protocols, by accurate estimation of traffic demand, valuable resources are more properly allocated to satellite terminals so that the amount of resources allocated, but not actually used for traffic transmission, can be reduced: ultimately, this improves the transmission delay of those terminals with higher traffic demand.
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
