• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.1A
• /
• pp.44-53
• /
• 2010

This paper proposes a traffic management policy for delay control in the wireless networks. The so-called EDD(Earliest Due Date) scheme is adopted as the packet scheduling policy, so that the service provision is performed in the order of the transmission urgency of the backlogged packets. In addition, we derive a formula to determine the contention window, one of the MAC parameters, with the goal of minimizing the non-work conserving characteristics of the traditional MAC scheme. This method eliminates the burden of the class-wise parameter settings which is typically required for the priority control. Simulations are performed to show the validity of the proposed scheme in comparison with the policy that adopts the class-level queue management such as the IEEE 802.11e standard. Smaller delays and higher rates of delay guarantees are observed throughout the experiments.

• Journal of the Korea Computer Industry Society
• /
• v.2 no.4
• /
• pp.547-564
• /
• 2001

In this paper a simulation has been performed to compare and evaluate the performance between the EPRCA(Enhanced Proportional Rate Control Algorithm) and EMRCA(Explicit Max_min Rate Control Algorithm) switches. The variation of the ACR at the source end system, the queue length, the utilization rate of the link bandwidth and the share fairness at the transient and steady states are used as the evaluation criteria for the simulation. The EMRCA switch is more stable than the EPRCA switch and reduces its buffer size. Also, it achieves a higher utilization rate of the link bandwidth than the EPRCA switch. The hardware complexity of the EMRCA switch is significantly lower than the EPRCA and other rate-based switches. Since it eliminates the necessity of the floating-point operation for calculation of the MACR(Mean Allowed Cell Rate) at the switch.

• The Journal of the Korea Contents Association
• /
• v.8 no.6
• /
• pp.34-42
• /
• 2008

MAC(Medium Access Control) is demanded to provide end-to-end QoS(Quality of Service) for a variety of traffic in the wireless networks. When all the traffic is integrated in the channel, the main difficulty of the MAC protocol is how to efficiently support multi-class traffic in the limited bandwidth wireless channel. In this paper, we proposed the dynamic bandwidth slot method for improving QoS of the real time traffics. In this paper, we used in-band scheme to send dynamic parameter and considering buffer size and delay variation, we enabled 2 state bits to send to base station in mobile station. The proposed algorithm is to guarantee QoS of real time traffic and maximize transfer efficiency in wireless networks.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.8 no.5
• /
• pp.1058-1067
• /
• 2004

Java virtual machine provides code compactness, simple execution engines, and platform-independence which are important features for small devices such as mobile or embedded device, but it has a big problem, such as low throughput due to stack-oriented operation. In this paper hardware lava accelerator targeted for mobile or embedded application is designed to eliminate the slow speed problem of lava virtual machine. The designed lava accelerator can execute 81 instructions of Java virtual machine(JVM)'s opcodes and be used as Java coprocessor of conventional 32-bit RISC processor with efficient coprocessor interface and instruction buffer. It consists of about 14,300 gates and its maximum operating frequency is about 50 Mhz under 0.35um CMOS technology.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.9A
• /
• pp.1383-1391
• /
• 1999

This paper presents a rate control method that minimizes global distortion under given target bit rates for video communication. This method makes the quality of reconstructed images better than that of the conventional ones based on R-D model at the same bit rates. Given a set of quantizers, a sequence of macroblocks to be quantized selects the optimal quantizer for each macroblock so that the total cost measure is minimized and the finite buffer is never in overflow. To solve this problem we provide a heuristic algorithm based on Lagrangian optimization using an operational rate-distortion framework and a quantization method follows H.263recommendation.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.19 no.5
• /
• pp.892-900
• /
• 1994

Recently, ITU-TSS recommends a service specific connection oriented protocol (SSCOP) which assures the successful transmission of signalling information for B-ISDN. In the SSCOP, there is a mechanism to exchange periodically status informations for both error and flow controls. In this paper, we analyze the SSCOP with a discrete-time queueing model. We consider two cases for link-by-link and end-to-end controls. As the performance measures, we investigate delay, throughput, and buffer size of the receiver. The average values of these measures are analyzed with respect to the loss probability of messages, the traffic load, and the exchange period of status information. We also verify the accuracy of this model with simulations.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.23 no.8
• /
• pp.1907-1914
• /
• 1998

This paper proposes the adaptive connection admission cotrol using the variale MRR(measurement reflection ratio) and the distribution of the number of cells arriving during the fixed interval. This distribution is estimated from the measured number of cells arriving at the output buffer during the fixed interval and traffic parameters specified by user. MRR is varied by the difference of estimated distribution and measurement distribution. As MRR is adaptively varied by estimated distribution error of accepted connections, it quickly reduces estimation error. Also, the scheduling scheme is proposed for multiplexed traffic with various traffic characteristics. For each traffic class, this scheme estimates adaptively equivalent bandwidth and schedules according to equivalent bandwidth ratio of each traffic class, so it improves cell loss rate and link utilization.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.1 no.2
• /
• pp.131-136
• /
• 2008

From the reciprocal connection by this Internet network researchs about the efficiency improvement of the whole system is accomplished with the method which reduces delays in message transmission. From here, we will do a comparative study between the user data program protocol (UDP) and the zero copy which does not use the buffer cache to fine out the valid method to improve the efficiency. In this thesis, I will change the message copy from execution process of the buffer cache of the TCP/IP on Unix OS with process on Linux OS. The object of conversion is to show you that the zero copy which doesn't use the buffer cache from transfer control class improves the communication efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.10A
• /
• pp.1554-1559
• /
• 2000

On ATM networks, MPEG video stream is transferred using CBR or VBR services. But because the MPEG video traffic varies greatly from time to time, it is very difficult to transfer the MPEG steam efficiently without loss of transmission bandwidth. Until now, the study on the traffic analysis and control on a single MPEG video stream has been done by many researchers, but the traffic analysis and control on a multiplexed traffic of multiple MPEG video streams has not been studied by any researcher. This paper proposes a multiplexing method to reduce the PCR and traffic variance of a multiplexed traffic of multiple MPEG video streams. By reducing the PCR of the multiplexed traffic, the multiplexed VBR traffic can be transferred efficiently with less loss of transmission bandwidth.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.16 no.1
• /
• pp.191-197
• /
• 2012

In this paper we propose the FQSM(Fairness and QoS Supporting MAC) protocol that supports fairness and Quality of Service(QoS). The received or measured data traffics will be assigned a priority level according to its transmission urgency in the FQSM. And the load prediction algorithm is used to support the fairness between different priority traffics. For this, the buffer length values of the nodes are continuously monitored for a some period. Based on the buffer length variations for this period, the order of transmission is determined. FQSM also adapts cross-layer concept to rearrange the data transmission order in each sensor node's buffer, saves energy consumption by allowing few nodes in data transmission, and prolongs the network lifetime.