• ETRI Journal
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• v.40 no.3
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• pp.337-346
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• 2018

In this paper, we propose a grant-aware (GA) scheduling algorithm that can provide higher throughput and lower latency than a conventional dual round-robin matching (DRRM) method. In our proposed GA algorithm, when an output receives requests from different inputs, the output not only sends a grant to the selected input, but also sends a grant indicator to all the other inputs to share the grant information. This allows the inputs to skip the granted outputs in their input arbiters in the next iteration. Simulation results using OPNET show that the proposed algorithm provides a maximum 3% higher throughput with approximately 31% less queuing delay than DRRM.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4B
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• pp.186-191
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• 2005

To provide fairness among different ONUs in EPON, the upstream channel remains idle for some time after OLT receives the buffer status from all ONUs every cycle, which decreases the utilization and increases the delay. To solve this deficiency, we present a new grant scheduling method. The method consists of dividing ONUs into several sets where OLT can schedule ONUs in one set while others will be transmitting their traffic. This method will better utilize the bandwidth of EPON. The numerical results show that the larger the number of ONU sets is the smaller the minimum overhead becomes.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.30 no.1
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• pp.59-65
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• 2007

HPI (High-speed Portable Internet) system which provides high speed internet services is going to be commercialized soon. Since HPI provides simultaneously four different service types such as UGS (Unsolicited Grant Service), rtPS (real time Polling Service), nrtPS(non-real time Polling Service), and BE (Best Effort) under different QoS (Quality of Service) requirements and limited wireless channel resources, efficient packet scheduling mechanisms are necessary to increase the utilization of channels as well as to satisfy the various QoS requirements. This study regards the traffic data to be served as time series and proposes a new packet scheduling algorithm based on the nonparametric statistical test. The performance of the newly proposed algorithm is evaluated through the simulation analysis using a simulator that can evaluate the performance of packet scheduling mechanisms under various values of system parameters and measures such as packet delay time, data transmission rate, number of loss packets, and channel utilization.

• ETRI Journal
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• v.26 no.2
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• pp.185-188
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• 2004

In this paper, we design a two-step scheduling algorithm to support multiple bandwidth allocation policies for upstream channel access in an Ethernet passive optical network. The proposed scheduling algorithm allows us a simultaneous approach for multiple access control policies: static bandwidth allocation for guaranteed bandwidth service and dynamic bandwidth allocation for on-demand, dynamic traffic services. In order to reduce the scheduling complexity, we separate the process of the transmission start- time decision from the process of grant generation. This technique does not require the timing information of other bandwidth allocation modules, so respective modules are free from a heavy amount of timing information or complex processing.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.390-393
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• 2003

In this paper, we study on an implementation of cell scheduler which arbitrates the ATM exchange efficiently and swiftly. The designed ATM cell scheduler of this paper is based on iSLIP scheduling algorithm. It is aimed at the high-speed implementation. The implemented cell scheduler approximately provides 100% throughput for cell scheduling. We present a basic structure for cell scheduler and describe by using the HDL and perform behavior level and timing simulation. The cell scheduler of this paper is designed to support 8-port switch fabric and can expand in 32-port switch fabric. The cell scheduler for supporting the 8-port switch fabric is designed in 2-stage pipelines for the grant and accept stages respectively.

• Journal of Communications and Networks
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• v.11 no.1
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• pp.36-41
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• 2009

The IEEE 802.16 wireless metropolitan area network (WMAN) standard is designed to correct expensive communication costs in CDMA-based mobile communication systems and limited coverage problems in wireless LAN systems. Thus, the IEEE 802.16e standard can provide mobile high-speed packet access between mobile stations and the Internet service provider through the base station with cheap communication fees. To efficiently accommodate voice over IP (VoIP) services in IEEE 802.16 systems, an uplink quality of service packet-scheduling scheme is proposed, and its performance is evaluated with an NS-2 network simulator in this paper. Numerical results show that this proposed scheme can increase the system capacity by 100% more than in the unsolicited rand service (UGS) scheme and 30% more than the extended real-time polling service (ertPS) scheme, respectively.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.8-18
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• 2009

CableLAB published DOCSIS 3.0 Specifications to supply broadband access to homes and small businesses. The primary technique of DOCSIS 3.0 Specification is channel bonding which provides cable operators with a flexible way to significantly increase up/downstream speeds. In this paper, we propose the upstream scheduler that serves channel bonding. Proposed scheduler consists of two sub-scheduler: bonding group scheduler and channel scheduler. Also, we propose three scheduling algorithms to allocate request bandwidth of CM to each bonding channel: equivalent scheduling algorithm, current request-based scheduling algorithm, and last grant-based scheduling algorithm. In order to evaluate the performance of these algorithms and DOCSIS 3.0 MAC protocol, we develop the DOCSIS 3.0 simulator with the network simulator, OPNET, to model DOCSIS network, CMTS, and CM. Our results show that equivalent scheduling algorithm is superior to others in the view of transmission delay and throughput and DOCSIS 3.0 protocol provides higher throughput than pre-DOCSIS 3.0 protocol.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.10
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• pp.714-719
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• 2004

The Controller Area Network (CAN) is being widely used in real-time control applications such as automobiles, aircraft, and automated factories. Unfortunately, CAN, in its current form, is not able to either share out the system bandwidth among the different devices fairly or to grant an upper bound on the transmission times experienced by the nodes connected to the communication medium as it happens, for instance, in the token-based networks. In this paper. we present the message scheduling for CAN, based on the distributed control scheme to integrate actuators and sensors in a humanoid robot. Besides introducing the new algorism, this paper also presents some performance figures obtained using a specially developed software simulator, while the behavior of the new algorism is compared with the traditional CAN systems, in order to see how effective they are.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.11A
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• pp.859-866
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• 2003

In this paper, we designed the bandwidth allocation scheme with priority consideration for upstream channel access of EthernetPON. The objective of our scheme is to control the multi services in more effective way according to their CoS(Class of Service) or QoS(Quality of Service). The designed scheme considers transmission priority in the both side of OLT and ONU. In the OLT's view, the Two-step scheduling algorithm is applied with which we can support multiple bandwidth allocation policies simultaneously, i.e. SBA for the time-sensitive, constant rate transmission services and DBA for the best-effort services. This Two-step scheduling algorithm reduces the scheduling complexity by separating the process of transmission start time decision from the process of grant generation. In the ONU's view, the proposed scheme controls 8 priority queues of the 802.1d recommended 8 service classes. Higher priority queue is serviced in prior during the allowed GATE time from OLT. The OPNET modeling and simulation result compares the performance of each bandwidth allocation policy with SBA or DBA only approach.

• Journal of the Korea Society for Simulation
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• v.15 no.3
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• pp.87-91
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• 2006

With the growth of the internet, the number of wireless internet users has increased continuously up to date. However, mobile communications could not support high speed transmission rate with cheap communication fee and wireless LAN has problems in providing terminal mobility and wide area connectivity, respectively. So the WMAN standard has been newly designed to make up for these limits. The initial 802.16 specification effectively offers a solution for providing fixed users with high speed wireless communication but it does not offer terminal mobility. So the 802.16d and 802.16e have been developed as the next generation solution that can support various PHY layer (SC, SCa, OFDM, OFDMA) and offer the terminal mobility. In this paper, we propose an effective uplink scheduling algorithm for VoIP with using UGS, and we show that our proposed algorithm is superior in view of average delay and management of uplink bandwidth to conventional rtPS algorithm and the scheme in reference, with using NS-2 network simulator.