Browsing by Author "Lin, Shiang-Jiun"

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Downlink Optimization and Performance of Relay-Assisted Cellular Networks in Multicell Environments
(2010-06-01)
Sheen, Wern-Ho
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Lin, Shiang-Jiun
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Huang, Chia-Chi
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電信工程研究所
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Institute of Communications Engineering
Deploying fixed relay stations (RSs) in traditional mobile cellular networks is widely recognized as a promising technology to improve cell coverage, user throughput, and system capacity, to save the transmit power of a mobile station (MS) in the uplink, and to provide a low-cost deployment for coverage extension. One crucial step toward developing such a relay-assisted cellular network is to fully evaluate its performance from both theoretical and practical viewpoints. In the literature, however, the system has only been evaluated for very limited system configurations: with a fixed number of RSs and locations and/or a fixed frequency-reuse pattern. This paper aims to investigate the downlink performance limits of a general relay-assisted network with optimized system parameters in a multicell environment. A genetic algorithm (GA) is proposed for the joint optimization of system parameters, including the number of RSs and their locations, frequency-reuse pattern, path selection, and resource allocation to maximize the system spectral efficiency (SE). Two types of quality of end-user experience (QoE), i.e., 1) fixed-bandwidth allocation (FBA) and 2) fixed-throughput allocation (FTA), are investigated along with two path-selection methods, i.e., 1) SE based and 2) signal-to-interference-plus-noise ratio (SINR) based. Numerical results show that significant improvement on system performance can be achieved with the optimized system parameters.
OLM: Opportunistic Layered Multicasting for Scalable IPTV over Mobile WiMAX
(2012-03-01)
Huang, Chih-Wei
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Huang, Shiang-Ming
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Wu, Po-Han
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Lin, Shiang-Jiun
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Hwang, Jenq-Neng
We propose Opportunistic Layered Multicasting (OLM), a joint user scheduling and resource allocation algorithm that provides enhanced quality and efficiency for layered video multicast over Mobile WiMAX. This work is a lead off and complete synergy of layered video multicasting with opportunistic concept. The target application is characterized by groups of users acquiring popular video programs over a fading channel. To accommodate various bandwidth requirements and device capability, video streams are coded into base and enhancement layers using scalable video coding technology. Correspondingly, the optimization problems, which select the best subset of users to receive a specific video layer and assign the most appropriate modulation and coding scheme for this video layer, are specifically formulated for both video layer types. We also design fast and effective algorithms to bridge the gap between theoretical throughput capacity and implementation concerns. Thus, the basic video quality can be efficiently guaranteed to all subscribers while creating most utility out of limited resources on enhancement information. To overcome the inevitable packet loss in a multicast session, an FEC rate adaptation scheme to approach theoretical performance is also presented. Favorable performance of the proposed algorithms is demonstrated by simulations utilizing realistic Mobile WiMAX parameters.
On the Uplink Performance and Optimization of a Relay-assisted Cellular Network
(2009)
Lin, Shiang-Jiun
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Sheen, Wern-Ho
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Huang, Chia-Chi
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電信工程研究所
;
Institute of Communications Engineering
Using relay stations (RSs) has been known as a promising technology to improve the system performance of a traditional cellular network. This paper aims to investigate the uplink performance of a relay-assisted cellular network with optimal system parameters. Two performance measures, average power consumption of mobile stations and uplink system spectral efficiency, are optimized by jointly considering the system parameters of RSs' locations, reuse patterns, path selections and resource allocation. A genetic algorithm along with a method of MAI (multiple access interference) estimation is proposed to solve the optimization problem. Numerical results show that significant improvement on system performance can be achieved from both power consumption and system spectral efficiency aspects if RSs are deployed and used in the optimal way.
Resource scheduling with directional antennas for multi-hop relay networks in Manhattan-like environment
(2007)
Lin, Shiang-Jiun
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Sheen, Wern Ho
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Fu, I-Kang
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Huang, Chia-chi
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電信工程研究所
Multi-hop relay (MR) networks have been proposed for user throughput improvement, coverage extension and/or capacity enhancement to the traditional mobile cellular networks. In particular, an MR network is being standardized by the IEEE 802.16j Task Group as an amendment to the IEEE 802.16e standard. This paper investigates the issue of resource scheduling for the IEEE 802.16j MR network in the Manhattan-like environment. New scheduling methods are proposed for the MR network with directional antennas equipped at both the base station and relay stations. Simulation results show that the system throughput can be dramatically increased by the proposed methods as compared to the system with omnidirectional antennas.