• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5B
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• pp.270-276
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• 2007

The proposed LDS(Link-status Dependent Scheduling) algorithm in HR-WPAN(High Rate-Wireless Personal Area Network) up to now aims at doing only throughput elevation of the whole network, when the crucial device is connected with worst-link relatively, throughput of this device becomes aggravation. The proposed the WGS(Worst-case Guaranteed Scheduling) algorithm in this paper guarantees throughput of the device which is connected with worst-link in a certain degree as maintaining throughput of all devices identically even if a link-status changes, decreases delay of the whole network more than current LDS algorithm. Therefore proposed WGS algorithm in this paper will be useful in case of guaranteeing throughput of a device which is connected worst-link in a certain degree in a design of HR-WPAN hereafter.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.249-251
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• 2007

The proposed LDS(Link-status Dependent Scheduling) algorithm in HR-WPAN up to now aims at doing only throughput elevation of the whole network, when the crucial DEV(Device) is connected with worst-link relatively, throughput of this DEV becomes aggravation, The proposed the WGS(Worst-case Guaranteed Scheduling) _algorithm in this paper guarantees throughput of the DEV which is connected with worst-link in a certain degree as maintaining throughput of all DEVs identically even if a link-status changes, decreases delay of the whole network more than current LDS algorithm Therefore proposed WGS algorithm in this paper will be useful in case of guaranteeing throughput of a DEV which is connected worst-link in a certain degree in a design of HR-WPAN hereafter.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.370-375
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• 1992

This paper deals with the scheduling and simulation for FMC(Flexible Manufacturing Cells). In order to achieve CIM, there is a critical need to link factory level and machine level. The primary functions performed by this link for all jobs issued to the shop floor and cell include short-term scheduling and dynamic operational scheduling. Here, hierarchical control structure is introduced to define these functions. And Intelligent scheduling through expert module is adopted for efficiency of FMC operation. Computer simulation reveals that expert scheduling method is better than heuristics in various performance index.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.5A
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• pp.469-474
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• 2006

In this paper, we develop a method that derive the average sector throughput of HSDPA system. This proposed method reflects the effects of AMC, scheduling and multi-code transmission, and is performed by simple calculation procedures such as link budget analysis. Link budget table is used to estimate a cell coverage in general. We modify the link budget table in order to calculate C/I of the user according to the location of the user in CDMA packet system employing AMC. Furthermore, we utilize the proposed method to analyze the effects of scheduling and multi-code transmission.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.4050-4067
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• 2014

In wireless sensor networks, link scheduling is a fundamental problem related to throughput capacity and delay. For a given set of communication requests $L=\{l_1,l_2,{\cdots},l_n\}$, the MLS (maximum link scheduling) problem aims to find the largest possible subset S of Lsuch that the links in S can be scheduled simultaneously. Most of the existing results did not consider bidirectional transmission setting, which is more realistic in wireless sensor networks. In this paper, under physical interference model SINR (signal-to-noise-plus-interference-ratio) and bidirectional transmission model, we propose a constant factor approximation algorithm MLSA (Maximum Link Scheduling Algorithm) for MLS. It is proved that in the same topology setting the capacity under unidirectional transmission model is lager than that under bidirectional transmission model. However, compared with some work under unidirectional transmission model, the capacity of MLSA is improved about 28% to 45%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.10
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• pp.876-884
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• 2012

This paper introduces two multi-hop delay factors which can be caused by conventional TDMA scheduling; queueing delay and delay by random link scheduling, and proposes a new sequential scheduling scheme to resolve these two factors. We also simulate the TDMA network with the proposed link scheduling scheme and compare it with conventional(random) link scheduling scheme in terms of end-to-end packet transmission delay. From the simulation results, the more the average hop distance increases, the more the difference of the delay performance of both scheduling schemes increases. When the average number of hops is 2.66, 4.1, 4.75, and 6.3, the proposed sequential scheduling scheme reduces the average end-to-end delay by about 22%, 36%, 48%, and 55% respectively when compared to the random scheduling scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.9
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• pp.4429-4445
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• 2019

As low-power and low-rate WSNs are being widely used for industrial applications, the scheduling of such applications becomes a critical issue to guarantee meeting the stringent requirements of determinism and tight latencies. This paper studies the link scheduling problem for real-time industrial applications in time-slotted channel hopping (TSCH) networks. We propose a heuristic algorithm for centralized link scheduling referred to as path-collision aware least laxity first (PC-LLF) algorithm, which dynamically prioritizes the packets based on the laxity time to the end-to-end deadlines and the amount of collisions that messages might deal with along their designated paths to the destination device. We propose schedulability analysis of real-time applications scheduled under our prioritization approach over TSCH networks, based on the literature on real-time schedulability analysis of multiprocessors and distributed systems. We show that our methodology provides an improved schedulability condition with respect to the existing approaches. Performance evaluation studies quantify to quantify the performance of our proposed approach under a variety of scenarios.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.4
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• pp.325-336
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• 2013

FlashLinQ, one of the typical D2D communication systems developed by Qualcomm, considers a single-tone communication based distributed channel-aware link scheduling method to realize the link scheduling process with low control overheads. However, considering the frequency selective fading effect of practical multi-path channel, the single-tone based SIR estimation causes a critical scheduling error problem because the received single-tone signal has quite different channel gain at each sub-carrier location. In order to overcome this problem, we propose a novel link scheduling method based on CAZAC (Constant Amplitude Zero Auto-Correlation) sequence for D2D communication system. In the proposed method, each link has a unique offset value set for the generation of CAZAC sequences. CAZAC sequences with the cyclic offsets are transmitted using multiple sub-blocks in the entire bandwidth, and then each device can obtain nearly full-band SIR using a good cyclic cross-correlation property of CAZAC sequence.

• Journal of Korea Multimedia Society
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• v.7 no.10
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• pp.1443-1451
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• 2004

In this paper we propose a new packet scheduling mechanism to improve TCP throughput and fairness with estimated link state information in wireless networks, in which mobile hosts are receivers. Since a priori estimated link state information is used in this proposed mechanism, the entire packet transmission time can be reduced. In other words, packets scheduling procedure is performed before packets are transmitted using estimated link state. The proposed mechanism also has an temporary FIFO queue to store packets which are on the head of queue and can not be transmitted due to bad link state. Using this temporary FIFO queue, HOL(Head of Line) problem of FIFO queue can be resolved.

• Journal of Information Technology Applications and Management
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• v.23 no.2
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• pp.61-80
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• 2016

The wireless mesh network (WMN) is a next-generation technology for data networking that has the advantage in cost and the flexibility in its construction because of not requiring the infra-structure such as the ethernet. This paper focuses on the optimal link scheduling problem under the wireless mesh network to effectuate real-time streaming by using the constraint programming. In particular, Under the limitation of half-duplex transmission in wireless nodes, this paper proposes a solution method to minimize the makespan in scheduling packet transmission from wireless nodes to the gateway in a WMN with no packet transmission conflicts due to the half-duplex transmission. It discusses the conflicts in packet transmission and deduces the condition of feasible schedules, which defines the model for the constraint programming. Finally it comparatively shows and discusses the results using two constraint programming solvers, Gecode and the IBM ILOG CP solver.