Browsing by Author "Chen, Yih-Shen"

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A joint power and rate assignment algorithm for multirate soft handoffs in mixed-size WCDMA cellular systems
(2007-05-01)
Liao, Ching-Yu
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Chang, Chung-Ju
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Wang, Li-Chun
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Chen, Yih-Shen
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交大名義發表
This paper proposes a joint power and rate assignment (JPRA) algorithm to deal with multirate soft handoffs (SHOs) in mixed-size wideband code division multiple access cellular systems. This JPRA algorithm contains a link proportional power allocation scheme and an evolutionary computing rate assignment method to determine an appropriate allocation of transmission power and service rate for multirate SHOs. It can achieve power balancing among cells better than the conventional site-selection diversity transmission scheme with best effort rate allocation. Simulation results show that the JPRA algorithm can achieve better cell's service coverage! and higher system capacity with and without the measurement errors during the active set selection.
A Novel Adaptive P-Persistent MAC Scheme for WLAN Providing Low Delay Variance
(2006)
Chang, Chung-Ju
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Yen, Frank C. M.
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Chen, Yih-Shen
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Huang, ChingYao
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電信工程研究所
The paper proposes and analyzes a novel adaptive p-persistent-based (APP) medium access control (MAC) scheme to provide low delay variance for IEEE 802.11 WLAN. The APP MAC scheme can differentiate permission probabilities of transmission for stations being incurred with different packet delays, and the permission probability is designed as a function of the numbers of retransmissions and re-backoffs so that stations being with larger packet delay can attain higher permission probability. Additionally, the scheme is modeled by a Markov-chain and successfully analyzed, where the system throughput and delay are derived. Results show that the proposed APP MAC scheme can achieve lower delay variance than conventional algorithms; it can effectively reduce the collision probability and the mean delay, therefore, the mean throughput is enhanced, as well.
An adaptive p-persistent MAC scheme for multimedia, WLAN
(2006-11-01)
Yen, Chih-Ming
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Chang, Chung-Ju
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Chen, Yih-Shen
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電信工程研究所
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Institute of Communications Engineering
The letter proposes an adaptive p-persistent-based (APP) medium access control (MAC) scheme for the IEEE 802.11e distributed WLAN supporting multimedia services. The APP MAC scheme adaptively gives differentiated permission probabilities to transmission stations which are in different access category and with various waiting delay. Simulation results show that the APP MAC scheme can improve the performance of multimedia WLAN, such as small voice packet dropping probability, low delay variation, and high system throughput, compared to conventional MAC algorithms.
An effective APP MAC scheme for multimedia WLAN-based DSRC networks
(2006)
Chang, Chung-Ju
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Yen, Frank C. M.
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Chen, Yih-Shen
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電信工程研究所
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Institute of Communications Engineering
The paper proposes an effective adaptive p-persistent-based (APP) medium access control (MAC) scheme for WLAN-based dedicated short-range communications (DSRC) networks supporting multimedia services. The APP MAC scheme adaptively gives differentiated permission probabilities to on board units (OBUs) which are in different access category and with various waiting delay. Simulation results show that the APP MAC scheme can improve the performance of multimedia WLAN-based DSRC networks, such as small real-time packet dropping probability, low delay variation, and high system throughput, compared to conventional MAC algorithms.
Analysis of an Adaptive P-Persistent MAC Scheme for WLAN Providing Delay Fairness
(2010-02-01)
Yen, Chih-Ming
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Chang, Chung-Ju
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Chen, Yih-Shen
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Huang, Ching Yao
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電機工程學系
The paper proposes and analyzes an adaptive p-persistent-based (APP) medium access control (MAC) scheme for IEEE 802.11 WLAN. The APP MAC scheme intends to support delay fairness for every station in each access, denoting small delay variance. It differentiates permission probabilities of transmission for stations which are incurred with various packet delays. This permission probability is designed as a function of the numbers of retransmissions and re-backoffs so that stations with larger packet delay are endowed with higher permission probability. Also, the scheme is analyzed by a Markov-chain analysis, where the collision probability, the system throughput, and the average delay are successfully obtained. Numerical results show that the proposed APP MAC scheme can attain lower mean delay and higher mean throughput. In the mean time. simulation results are given to justify the validity of the analysis, and also show that the APP MAC scheme can achieve more delay fairness than conventional algorithms.
Maximum freedom last scheduling algorithm for downlinks of DSRC networks
(2007-06-01)
Chang, Chung-Ju
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Cheng, Ray-Guang
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Shih, Hao-Tang
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Chen, Yih-Shen
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電信工程研究所
This paper proposes a maximum freedom last (MFL) scheduling algorithm for downlinks, from the roadside unit to the onboard unit (OBU), of dedicated short-range communication networks in intelligent transportation systems, to minimize the system handoff rate under the maximum tolerable delay constraint. The MFL scheduling algorithm schedules the service ordering of OBUs according to their degree of freedom, which is determined by factors such as remaining dwell time of service channel, remaining transmission time, queueing delay, and maximum tolerable delay. The algorithm gives the smallest chance of service to the OBU with the largest remaining dwell time, the smallest remaining transmission time, and the largest weighting factor, which is a function of the queueing delay and the maximum tolerable delay. Simulation results show that the MFL scheduling algorithm outperforms the traditional first-come-first-serve and earliest-deadline-first methods in terms of service failure and system handoff rates.
Method for power-efficient transmission supporting integrated services over wireless local area network
(2006-11-16)
Shih, Chih-Yung
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Cheng, Ray-Guang
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Chang, Chung-Ju
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Chen, Yih-Shen
This invention provides a method for power-efficient transmission supporting integrated service over WLAN. The said invention combines the polling-based and the contention-based mechanisms, named on-demand polling (ODP). In the ODP scheme, a voice station is in the polling list when it is in the active mode. During the idle mode, it is configured to operate in the sleep mode for saving power. Also, it adopts the contention-based mechanism to join the list again while returning from the idle mode. On the other hand, the data station adopts the contention-based mechanism to transmit its packets over WLAN. In addition, to achieve service differentiation, the said invention also employs a prioritized access probability for voice over data services. Simulation results show that the said invention can reduce the power consumption for voice stations and enhance the throughput for data stations.
Situation-aware data access manager using fuzzy Q-learning technique for multi-cell WCDMA systems
(2006-09-01)
Chen, Yih-Shen
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Chang, Chung-Ju
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Ren, Fang-Ching
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交大名義發表
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National Chiao Tung University
This paper proposes a novel situation-aware data access manager using fuzzy Q-learning technique (FQ-SDAM) for multi-cell WCDMA systems. The FQ-SDAM contains a fuzzy Q-learning-based residual capacity estimator (FQ-RCE) and a data rate scheduler (DRS). The FQ-RCE can accurately estimate the situation-dependent residual system capacity, and appropriately chooses the received interference powers from the home-cell and adjacent-cell as input linguistic variables, which simplifies the multi-cell environment into a single-cell environment by applying a perceptual coordination mechanism. The DRS can effectively allocate the resource for non-real-time terminals by modifying the exponential rule [10], which considers the effect of interference on adjacent cells. Simulation results show that, compared to the link and interference-based demand assignment (LIDA) scheme proposed in [7], FQ-SDAM can effectively reduce the packet error probability and improve aggregate throughput of the non-real-time services in both the homogeneous and non-homogeneous multi-cell WCDMA environments. Additionally, the modified exponential rule achieves better system performance than the original exponential rule.