• Title, Summary, Keyword: Time Slot

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A Study on the Time-slot Allocation Methods for the Multi-slot Calls on ATM Telephone Network (ATM 통화로 망에서의 다중호 배치방법에 대한 연구)

  • 박경태
    • Journal of the Institute of Convergence Signal Processing
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    • v.5 no.1
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    • pp.73-78
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    • 2004
  • There are random, continuous, and periodic allocation methods in the time slot sequence integrity for the multi-slot call. In the T-S-T switch, there are 2 time switch and the 2*2 space switch. Three time-slot allocation methods are suggested for the simulation. In the simulation, the searching times for time-slots on a multi-slot call is chosen to 32, and the simulation time is chosen to 100,000 seconds. Three kinds of calls are supposed for a multi-slot call : one time-slot call, two time-slot call, and 6 time-slot call. In the simulation, the carried traffic and the blocking probability are calculated on the 3 different traffic cases of 8:1:1, 6:2:2, 4:3:3(one time-slot : two time-slot : 6 time-slot) multi slot calls. It is shown that the blocking probability for the periodic time slot allocation method is best. As a result, the periodic time-slot allocation method is the proper one for the multi-slot ATM switch.

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Time Slot Exchange Protocol in a Reservation Based MAC for MANET

  • Koirala, Mamata;Ji, Qi;Choi, Jae-Ho
    • Journal of the Institute of Convergence Signal Processing
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    • v.10 no.3
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    • pp.181-185
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    • 2009
  • Recently, much attention to a self-organizing mobile ad-hoc network is escalating along with progressive deployment of wireless networks in our everyday life. Being readily deployable, the MANET (mobile ad hoc network) can find its applications to emergency medical service, customized calling service, group-based communications, and military purposes. In this paper we investigate a time slot exchange problem found in the time slot based MAC, that is designed for IEEE 802.11b interfaces composing a MANET. The paper provides a method to maintain the quality of voice call by providing a new time slot when the channel assigned for that time slot gets noisy with interferences induced from other nodes, which belong to the same and/or other subgroups. In order to assess the performance of the proposed algorithm, a set of simulations using the OPNET modeler has been performed assuming that the IEEE 802.11b interfaces are operating under a modified MAC, which is a time slot based reservation MAC implemented in the PCF part of the superframe. In a real-time voice call service over a MANET of a size 500 ${\times}$ 500 meter squares with the number of nodes up to 100, the simulation results are collected and analyzed with respect to the packet loss rate and packet delay. The results show us that the proposed time slot exchange protocol improves the quality of voice call over that of plain DCF.

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Efficient Scheduling Algorithm for Sequential Multipurpose Batch Processes (순차적 다목적 회분식 공정을 위한 효과적인 일정계획)

  • 강진수;복진광;문성득;박선원;이태용
    • Journal of Institute of Control, Robotics and Systems
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    • v.6 no.5
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    • pp.426-432
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    • 2000
  • A novel mixed-integer linear programming model for the short-term scheduling of a sequential multipurpose batch plant is addressed. First, a time slot domain to each unit is introduced. By assigning each time slot to a product, we obtain the production sequence that minimizes makespan. For multiple-unit assignment problem where a few parallel units with the same function exist, production paths are defined for the distinction of the same stage with a different unit. As a second issue, the model adapted for sequence dependent changeover is presented. For a time slot of a unit, if a product is assigned to the time slot and a different product is assigned to the adjacent time slot, the changeover time considering this situation is included. The performance of the proposed models are illustrated through two examples.

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Performance of a time slot searching mechanism in multi-rate circuit switching system

  • Roh, Seung-Kye;Kook, Kwang-Ho;Lee, Jae-Sup;Chung, Min-Young;Sung, Dan-Keun
    • Korean Management Science Review
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    • v.10 no.1
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    • pp.127-137
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    • 1993
  • The blocking probabilities of nx64Kb/s multi-slot calls are generally much higher than that of single slot calls. In order to improve these blocking probabilities of multi-slot calls, we propose a scheme which searches the different numbers of time slots for different types of calls. We analyze the performance of our scheme in a double-buffered time-space-time switching network which accommodates multi-slot calls as well as single-slot calls. The proposed method yields the reduced blocking probabilities, the increased traffic handling capacity and teh reduced CPU processing load, compared with those of the conventional methods.

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An Improved Contention Access Mechanism for FPRP to Increase Throughput

  • Yang, Qi;Zhuang, Yuxiang;Shi, Jianghong
    • ETRI Journal
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    • v.35 no.1
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    • pp.58-68
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    • 2013
  • Five-phase reservation protocol (FPRP) is a contention-based media access control protocol for wireless ad hoc networks. FPRP uses a five-phase reservation process to establish slot assignments based on time division multiple access. It allows a node to reserve only one slot in an information frame. Once a node has reserved a slot, it will cease contending for other slots. As a result, there may be less contending nodes in the remaining slots, so the time slots in an information frame are not fully used by FPRP. To improve time slot utilization, this paper proposes an improved pseudo-Bayesian algorithm, based on which an improved contention access mechanism for FPRP is proposed, in which nodes are allowed to contend for more than one slot in a reservation frame according to a certain probability/priority. Simulation results indicate that the proposed mechanism performs better than FPRP in time slot utilization and hence the network throughput under various scenarios.

A Study of Collision Avoidance Methods For a STDMA Algorithm (STDMA 알고리즘에서의 충돌 회피 방법에 관한 연구)

  • 김현재;김영호
    • Proceedings of the Korean Information Science Society Conference
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    • pp.124-126
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    • 2002
  • 최근의 TDMA(Time Division Multiple Access) 알고리즘에 대한 발전 방향을 살펴보면 크게 두 가지로 요약할 수 있다. 먼저, 대용량의 데이터 - 멀티미디어 데이터 등 - 에 대한 활용이 많아짐에 따라 전송할 데이터를 적절하게 Scheduling하여 전송 효율을 증대시키는 접근 방향이 있으며, 또 다른 접근으로는 Time Slot에 대한 재사용성이나 Slot 할당 기법의 개선을 통하여 성능을 향상시키는 방법이 있다. 본 논문에서는 후자에 거론된 Time Slot에 대한 재사용성이나 Slot 할당 기법의 개선 방법 중의 하나인 STDMA(Self-organized TDMA)알고리즘에서, Slot 할당 시의 충돌 회피 방법을 고려하여 기존의 STDMA 알고리즘의 효율을 향상시키고자 한다. 현재 STDMA 알고리즘에서는 가용한 통신 범위 내에서의 Slot에 대한 할당 여부가 알고리즘 내에서 정의되고 있다. 따라서 부가적인 알고리즘의 추가가 없이 Slot할당 상황을 알 수 있으며, 이를 통하여 Slot 할당 단계에서 충돌 회피 방법을 추가하여 Conflict를 회피하도록 할 수 있다.

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A Performance Index for Time Slot Allocation in Link-16 Relative Navigation System

  • Lee, Jin Hyuk;Lee, Ju Hyun;Noh, Jae Hee;Lim, Deok Won;Park, Chansik;Lee, Sang Jeong
    • Journal of Positioning, Navigation, and Timing
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    • v.6 no.3
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    • pp.117-123
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    • 2017
  • In this paper, we propose a performance index that can compare the position estimation performance according to the time slot allocation order, which is superior in the position estimation performance in the operation of the Link-16 based relative navigation system. In order to verify the validity of the performance index, a software-based Link-16 relative navigation system performance analysis platform composed of a signal generator, a signal reception and navigation algorithm execution unit, and a performance analysis unit was designed. Using the designed software platform, we analyzed the relationship between proposed performance index and position estimation performance according to time slot allocation order in the same position reference (PR) arrangement. The performance index of the proposed time slot allocation is expected to be utilized not only for the Link-16 system, but also for the Time Division Multiple Access (TDMA)-based navigation system.

The Intermediate Channel Assignment based on Channel Status in High-rate WPAN (HR-WPAN에서 채널 상태에 따른 우회 채널 할당)

  • Lee Jung-Yun;Kim Sung-Su;Kim Jang-Hyung;Song Wang-Cheol
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.10 no.5
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    • pp.832-842
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    • 2006
  • Wireless Personal Area Networks(WAPANs) are designed for short-range ad hoc connectivity among portable devices. They have gained much attention in the industry recently. One of them, High-rate WPAN, is designed to support multimedia traffic that requires high data rates. But, High-rate WPAN standards don't specify the time slot assignment scheduling method of CAT(Channel Time Allocation). So, there has been many studies regarding time slot assignment scheduling of CAT. However, present studies involve demerits about not applying various types of errors in air interlace or having a starvation of a specific DEV(data device). In this paper, we propose algorithms about supplying the intermediate channel assignment in order to avoid these demerits. This method will help other methods that use time slot assignment scheduling of CTA.

Time Slot Assignment Algorithm with Graph Coloring (그래프 채색에 의한 타임 슬롯 할당 알고리즘)

  • Kwon, Bo-Seob
    • The Journal of the Korea Contents Association
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    • v.8 no.5
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    • pp.52-60
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    • 2008
  • A simple Time Division Multiplex(TDM) switching system which has been widely in satellite networks provides any size of bandwidth for a number of low bandwidth subscribers by allocating proper number of time slots in a frame. In this paper, we propose a new approach based on graph coloring model for efficient time slot assignment algorithm in contrast to network flow model in previous works. When the frame length of an initial matrix of time slot requests is 2's power, this matrix is divided into two matrices of time slot requests using binary divide and conquer method based on the graph coloring model. This process is continued until resulting matrices of time slot requests are of length one. While the most efficient algorithm proposed in the literature has time complexity of $O(N^{4.5})$, the time complexity of the proposed algorithm is $O(NLlog_2L)$, where N is the number of input/output links and L is the number of time slot alloted to each link in the frame.

System Performance Improvement of IEEE 802.15.3a By Using Time Slot Synchronization In MAC Layer (UWB MAC의 Time Slot 동기를 통한 시스템 성능 개선)

  • Oh Dae-Gun;Chong Jong-Wha
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.43 no.3
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    • pp.84-94
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    • 2006
  • In this paper, we propose the algorithm to reduce guard time of UWB MAC time slot for throughput gain. In the proposed draft by multiband ofdm alliance (MBOA), Guard time of each medium access slot (MAS) is composed of shortest inter-frame space (SIFS) and MaxDrift which is the time caused by maximum frequency offset among devices. In this paper, to reduceguard time means that we nearly eliminate MaxDrift term from guard time. Each device of a piconet computes relative frequency offset from the device initiating piconet using periodically consecutive transferred beacon frames. Each device add or subtract the calculated relative frequency offset to the estimated each MAS starting point in order to synchronize with calculated MAS starting point of the device initiating piconet. According to verification of simulations, if the frequency offset estimator is implemented with 8 decimal bit, the ratio of the wasted time to Superframe is always less than 0.0001.