• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37 no.7B
• /
• pp.489-498
• /
• 2012

Recently, as the interest in Green IT is exponentially increased, EPON with sleep mode has been studied to reduce energy consumption in access network. In oder to guarantee cyclic sleep for ONU(Optical Network Units), EPON with sleep mode transmits upstream and downstream data at the same time. However, since conventional algorithms for sleep mode in EPON allocate bandwidth to each ONU according to upstream bandwidth request, the QoS of downstream data is not guaranteed when the offered load of OLT is larger than that of ONU. In this paper, we propose a bandwidth allocation algorithm for improving QoS in EPON with sleep mode. The proposed algorithm compares its size with an upstream request of ONU when a downstream buffer in the OLT exceeds a QoS threshold. And then it allocates selectively a bandwidth that satisfies the required QoS between the bandwidth request of ONU and OLT. Therefore, the proposed algorithm can save energy through cyclic sleep of ONUs while guaranteeing the QoS of up/downstream data. In order to evaluate the proposed algorithm, we perform simulation in terms of total sleep time of ONUs, queueing delay between OLT and ONU, and the utilization of allocated bandwidth at OLT through OPNET.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.48 no.9
• /
• pp.50-57
• /
• 2011

Conventional bus system architectures are composed of several components such as master, arbiter, decoder and slave modules. The arbiter plays a role in bus arbitration according to the selected arbitration method, since several masters cannot use the bus concurrently. Typical priority strategies used in high performance arbiters include static priority, round robin, TDMA and lottery. Typical arbitration algorithms always consider the bus priority primarily, while the bus utilization is always ignored. In this paper, we propose an arbitration method using bus utilization for the operating block of each master. We verify the performance compared with the other arbitration methods through the TLM(Transaction Level Model). Based on the performance verification, the conventional fixed priority and round-robin arbitration methods cannot set the bus utilization. Whereas, in the case of the conventional TDMA and lottery arbitration methods, more than 100,000 cycles of bus utilization can be set by the user, exhibiting differences of actual bus utilization up to 50% and 70%, respectively. On the other hand, we confirm that for the proposed arbitration method, the matched bus utilization set by the user was above 99% using approximately 1,000 cycles.

• Journal of information and communication convergence engineering
• /
• v.9 no.5
• /
• pp.539-544
• /
• 2011

In this paper, a parameter optimization method of RIO-DC (RED (Random Early Detection) with In and Out-De-Coupled Queues) scheme for Assured Service (AS) in Differentiated Services (DiffServ) is proposed. In order to optimize QoS (Quality of Service) performance of the RIO-DC policy for AS in terms of maximum tolerable latency, link utilization, fairness, etc., we should design router nodes with proper RIO-DC operating parameter values. Therefore, we propose a RIO-DC configuration method and the admission control criterion, considering the allocated bandwidth to each subclass and the corresponding buffer size, to increase throughput for In-profile traffic and link utilization. Simulation results show that RIO-DC with the proposed parameter values guarantees QoS performance comparable with the RIO scheme and it improves fairness between AS flows remarkably.

• Proceedings of the IEEK Conference
• /
• 2008.06a
• /
• pp.777-778
• /
• 2008

The partitioning problem is one of efficient issues on designing an excellent DVE. A brilliant partitioning method is related with assigning several avatars into the suitable servers with well balancing the growing requirement of bandwidth and computational resources in DVE. In this paper, a new method LCAA is proposed. The LCAA is a new partitioning method that balancing the CPU utilization of servers in DVE especially.

• Proceedings of the IEEK Conference
• /
• 1999.11a
• /
• pp.499-502
• /
• 1999

This paper presents a PCI (Peripheral Component Interconnect) controller embedded in a multimedia processor, called FLOVA (FLOating point VLIW Architecture), targeting for 3D graphics applications. Fast I/O interfaces are essential for multimedia processors which usually handle large amount of multimedia data. Therefore, in FLOVA, PCI bus is adopted for I/O interface due to fast burst transaction. However, there are several problems in implementation and verification to use burst transaction of PCI. It is difficult to handle data transaction between two units which have two different operating frequency. FLOVA has more higher operating frequency about 100MHz than that of PCI local bus and it makes lower utilization of FLOVA bus. Also, traditional simulation is not sufficient for verification of PCI functionality. In this paper, we propose buffering schemes to implement the PCI controller with wide bandwidth and high bus utilization. Also, this paper shows how to verify the PCI controller using real PCI bus environments before its fabrication.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.3B
• /
• pp.390-397
• /
• 2010

This paper presents an effective IPTV channel control algorithm considering network utilization and channel zapping time. The proposed algorithm keeps maximum average channel zapping time of each subscriber in the tolerable range with low network bandwidth usage by adjusting the type of each channel and the number of additional intra frames inserted into each channel. Finally, experimental results are provided to show the performance of the proposed algorithm.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2002.05a
• /
• pp.426-433
• /
• 2002

This paper deals with an offline routing problem, which can be used as an explicit routing procedure in MPLS(Multiprotocol Label Switching) network, for traffic engineering. This problem is formulated as an MIP(Mixed Integer Programming) with the objective function which is to minimize the sum of the maximum link utilization for load balancing (link utilization) and the routing cost. Constraints arc composed of link capacity restriction and demand requirement that has origin-destination pair, bandwidth requirement and hop restriction. The problem is proved to be NP-hard so that the Lagrangean relaxation method is applied to propose a Lagrangean heuristic. To test the effectiveness & efficiency of the proposed algorithm, computational experiments are performed with numerical instances. The experiment results show that the proposed algorithm solves the problem within a reasonable time.

• The Journal of the Korea Contents Association
• /
• v.9 no.8
• /
• pp.73-83
• /
• 2009

TCP(Transmission Control Protocol) is currently used connection-oriented protocol as a typical transport layer protocol in the Internet. However, it has deficiency not be able to communicate with other TCP entities when any link included in the path is down because of single-homing on single path. SCTP(Stream Control Transmission Protocol) suggested as the new transport layer protocol supports multi-homing feature, which provides several paths between source and destination. It can communicate with other SCTP entities using alternate path even when any link on the primary path is down. This paper aims to measure and analyze the multi-homing effect of SCTP over TCP in case of link-down using NS-2 simulator. We classify SCTP into $SCTP_{single-homing}$ and $SCTP_{multi-homing}$ because SCTP with single-homing can also be used like TCP. We measured throughput and bandwidth utilization varying link-down duration, bandwidth, and RTT(round trip time), Simulation results show that throughput of $SCTP_{multi-homing}$ is more than that of TCP by 18 % on average. It is also shown that $SCTP_{multi-homing}$ on varying RTT and bandwidth increases the throughput of TCP by 'l7% and 9% on average, respectively in the link-down environment. In above cases, more or less difference between $SCTP_{single-homing}$ and TCP on throughput and bandwidth utilization was found To summarize, multi-homing effect of SCTP over TCP on throughput is about 18 % on average in the link-down environment This experimental result can be used as the benchmark in order to estimate the multi-homing effect of SCTP over TCP when the link-down happens in the real Internet.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.11A
• /
• pp.1709-1716
• /
• 2000

ATM 스위치에서 입력 트래픽의 링크 이용의 불확실성과 입력 트래픽에 대한 예측 오류 등으로 인한 폭주가 발생될 가능성을 완전히 배제할 수 없기 때문에 스위치내부에서 폭주 발생을 억제할 수 있는 방법이모새되어야 한다.본 논문에서는 스위치 내부 링크의 대역 사용량을 측정하여 폭주 및 트래픽 제어를 수행하고 링크 이용률을 최대화하기 위한대역 할당 알고리즘을 제안한다. 폭주가 발생한 링크에 대하여 짧은 시간 내에 폭주를 해결하고 폭주가 발생하지 않은 링크에서는 사용하고 남은 여분의 대역을 공평하게 할당함으로서 링크의 이용률을 극대화할 수 있으므로 트래픽 관리를 보다 쉽고 효율적으로 수행할 수 있다.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.35S no.9
• /
• pp.28-34
• /
• 1998

In ATM networks CBR data traffic is sent in constant bit rate, and VBR data traffic in variable bit rate. Therefore unused bandwidth at network capacity may exist. To avoid waste of network resourcesm, ABR traffic utilizes the unused bandwidth to the utmost after CBR and VBR data traffic being first served. In this paper, a transfer rate-based congestion control algorithm is proposed for efficient ABR service in ATM networks. In the proposed algorithm the ATM switch first calculates bandwidth according to variable cell transfer rate in an ABR source. records this value in ER field in a RM cell, and then transmits a RM Cell to an ABR source. In this way the proposed algorithm dynamically allocates bandwidth to each ABR source, and the switch also can rapidly adapt to a change of a transfer rate of an source. The performance simulation of the proposed algorithm has batter performance in terms of source condition and link utilization.