• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.3 no.2
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• pp.22-29
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• 1992

In recent years there has been increased interest in a class of multiple-access techniques known as code division multiple-access(CDMA). As the trend for ever increasing data transmission rate and high error performance continues while conserving bandwidth, the needs arise for good highrate R=b/v convolu- tional codes such as punctured codes. In this paper, the packet error propability has been analyzed in code division multiple-access packet radio system which utilize punctured convolutional code and hard-decision Viterbi decoding.

• The Transactions of the Korea Information Processing Society
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• v.6 no.11S
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• pp.3190-3198
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• 1999

Because of the rapid growth of the mobile communication, the need for the mobile internet access has grown up as well. since the current mobile communication network, however, is optimized for a voice communication system, which exclusively occupies a channel for a given time, it is not suitable for variable rate packet data. In order to support the mobile internet access, it is essential do design a reasonable packet switching network which supports the mobility. Since mobile packet network has longer latency, high speed switching and QoS are required to meet the user's requirements. In this paper, we suggest an resonable way to construct a network and its operation procedures utilizing GPRS(General Packet Radio Service) network and MPLS(Multi Protocol Label Switching) to provide a high speed switching and QoS mobile internet access. GPRS is used as a network which supports the mobility and MPLS guarantees the QoS and high speed IP protocol transmission based on the ATM switching technology.

• Proceedings of the Korea Technology Innovation Society Conference
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• 2001.11a
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• pp.3-17
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• 2001

In this paper, we compare the market performances under circuit pricing whereby users are charged based on their length of usage time and under packet pricing whereby users are charged based on the amount of information received. We show that, if packet pricing is introduced, the market price rises contrary to the government's expectation but that the overall social welfare is unambiguously increased because packet pricing reflects the social cost properly while circuit pricing does not. Also, we show that, if delivery of multi-media files requires a much higher speed, a move to packet pricing lowers the price of multi-media transmission, thereby increasing the usage of multimedia data in the absence of congestion, which may not be the case in the presence of congestion.

• ETRI Journal
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• v.22 no.3
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• pp.1-9
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• 2000

Self-Clocked Fair Queueing (SCFQ) algorithm has been considered as an attractive packet scheduling algorithm because of its implementation simplicity, but it has unbounded delay property in some input traffic conditions. In this paper, we propose a Rate Proportional SCFQ (RP-SCFQ) algorithm which is a rate proportional version of SCFQ. If any fair queueing algorithm can be categorized into the rate proportional class and input is constrained by a leaky bucket, its delay is bounded and the same as that of Weighted Fair Queueing (WFQ) which is known as an optimal fair queueing algorithm. RP-SCFQ calculates the timestamps of packets arriving during the transmission of a packet using the current value of system potential updated at every packet departing instant and uses a starting potential when it updates the system potential. By doing so, RP-SCFQ can have the rate proportional property. RP-SCFQ is appropriate for high-speed packet-switched networks since its implementation complexity is low while it guarantees the bounded delay even in the worst-case input traffic conditions.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.3
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• pp.65-75
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• 1998

We consider connection-oriented wireless cellular networks such as the second generation wireless cellular networks and wirelss ATM networks. In these networks, a separate forward signaling channel is provided for the transmission of paging and channel allocation packets. When a call destined to a user is requested, all the base stations in the user's current location area broadcast the corresponding paging packet across forward signaling channels. By slot mode operation and paging group allocation for fusers in a location area, we can reduce relative power consumption level at battery-operated terminals. However, a sthe number of paging groups is increased for lowering relative power consumption level, a paging packet experiences higher delay to access the forward signaling channel. For the pre-negotiated quality-of-service level, paging packet delay level must be limited. In this paper, we consider static and dynamic multiplexing schemes for paging packets, and develop an analytical method for calculating paging packet delay and relative power consumption levels. Using this analytial method, we investigate the effect of network parameters on the paging packet delay and relative power consumption levels.

• Journal of Communications and Networks
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• v.7 no.1
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• pp.36-44
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• 2005

In this paper, we present a retransmission power adjustment (RPA) scheme for DS/SSMA ALOHA packet radio systems with packet combining. In the proposed RPA scheme, retransmission power is adjusted in such a way that the erroneously-received packet can be recovered with a minimized interference to other user packets. We analyze the performance of the system with the RPA by employing the equilibrium point analysis (EPA), and confirm that the results obtained from the EPA are very close to the simulation results in low power cases. Simulation results demonstrate that the RPA scheme brings forth performance gain in the throughput and the average delay while saving a significant amount of transmission power. We also investigate the stability of the system from the EPA results, and conclude that the system becomes stable as the offered load increases or the level of retransmission power decreases.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.6
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• pp.21-28
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• 2016

This paper presents a cooperative transmission scheme for underwater acoustic sensor networks to improve packet transmission rate and reduce energy consumption. Source node transmits duplicated information relayed by distributed antennas called a virtual antenna array. Destination node combines that information to reduce packet error rate. The suggested cooperative scheme enhances the reliability by providing high diversity gains through intermediate relay nodes to overcome the distinct characteristics of the underwater channel, such as high transmission loss, propagation delay, and ambient noises. It is suggested that the algorithm select destinations and potential relays from a set of neighboring nodes that utilize distance cost, the residual energy of each node and local measurement of the channel conditions into calculation. Simulation results show that the proposed scheme reduces average energy consumption, response time, and increases packet delivery ratio compared with the SPF(Shortest Path First) and non-cooperative scheme using OPNET Moduler.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.4
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• pp.741-746
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• 2012

Transmission control protocol(TCP) widely used as a transport protocol in the Internet includes a loss recovery function that detects and recovers packet losses by retransmissions. The loss recovery function consists of the two algorithms; fast retransmit and fast recovery. There have been researches to avoid nonnecessary retransmission timeouts (RTOs), which leads to selective acknowledgement (SACK) option and limited transmit scheme that are standardized by IETF (Internet Engineering Task Force). Recently, a method that covers the case in which a retransmitted packet is lost again has been propsed. The method, however, is not proved in terms of the additive increase multiplicative decrease (AIMD) principle of TCP congestion control. In this paper, therefore, we analyzed the method in terms of the principle by ns-simulations.

• Journal of Korea Society of Industrial Information Systems
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• v.22 no.1
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• pp.33-40
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• 2017

In this Paper, Analyse the Steady State Behavior of TCP and TFRC with Packet Error when both TCP and TFRC Flows Co-exist in the Network. First, Model the Network with TCP and TFRC Connections as a Discrete Time System. Second, Calculate Average Round Trip Time of the Packet Between Source and Destination on Packet Loss Environment. Then Derive the Steady State Performance i.e. Throughput of TCP and TFRC, and Average Buffer Size of RED Router Based on the Analytic Network Model. The Throughput of TCP and TFRC Connection Decrease Rapidly with the Growth of Sending Window Size and Their Transmission Rate but Their Declines become Smoothly when the Number of Sending Window Arrives on Threshold Value. The Average Queue Length of RED Router Increases Slowly on Low Transmission Rate but Increases Rapidly on High Transmission Rate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.12B
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• pp.2109-2119
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• 2000

In this paper, the Packet CDMA Reservation ALOHA protocol is proposed to support the multi-traffic services such as voice and videophone services with handoff calls, high-rate data and low-rate data services efficiently on the multi-rate transmission in uplink cellular systems. The frame structure, composed of the access slot and the transmission slot, and the proposed access permission probability based on the estimated number of contending users for each service are presented to reduce MAI. The assured priority to the voice and the videophone handoff calls is given through higher access permission probability. And through the proposed code assignment scheme, the voice service can be provided without the voice packet dropping probability in the CDMA/PRMA protocols. The code reservation is allowed to the voice and the videophone services. The low-rate data service uses the available codes during the silent periods of voice calls and the remaining codes in the codes assigned to the voice service to utilize codes efficiently. The high-rate data service uses the assigned codes to the high-rate data service and the remaining codes in the codes assigned to the videophone service. Using the Markov-chain subsystem model for each service including the handoff calls in uplink cellular systems, the steady-state performances are simulated and analyzed. After a round of tests for the examples, through the proposed code assignment scheme and the access permission probability, the Packet CDMA Reservation ALOHA protocol can guarantee the priority and the constant QoS for the handoff calls even at large number of contending users. Also, the data services are integrated efficiently on the multi-rate transmission.