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Sung-Kwan Youm Meejoung KIM Chul-Hee KANG
This paper considers the reliable multicast transport protocols used in hybrid networks that include wired and wireless networks and transparent proxy servers. We present four analytic performance models of two extreme reliable multicast transport protocols, sender-initiated and receiver-initiated, and supported and unsupported by transparent proxy servers are considered in each reliable multicast protocol. We analyze the throughputs of these four different models mathematically. Numerical results show that transparent proxy servers give good effects to overall performance. Furthermore, the receiver-initiated reliable multicast supported by transparent proxy servers gives better performances of total throughput than sender-initiated reliable multicast supported by transparent proxy servers. We provide efficiency criterion of the optimal number of transparent proxy servers for each protocol under varying wireless loss probabilities. Numerical results are verified by simulations.
Meejoung KIM Chung Gu KANG Ramesh R. RAO
This letter proposes a packet length-based group-wise transmission (LGT) rate scheduling scheme for non-real time data service for the uplink of direct sequence code division multiple access (DS/CDMA) system using the burst switching scheme to support the integrated voice/data service. The LGT scheme optimally determines two different rate groups and their optimal data rates so as to minimize the average packet transmission delay. It has shown that the packet transmission delay performance can be significantly improved over the conventional single-rate packet transmission scheme for integrated voice/data service. Furthermore, a main feature of the proposed scheme is simplicity in its implementation.
This letter shows the performance comparisons of several different rate scheduling schemes for non-real time data service over the uplink of burst switching-based direct sequence code division multiple access (DS/CDMA) system to support the integrated voice/data service. The closed-form solution of optimal scheduling formulation, which minimizes average transmission delay when all of the active data users are transmitting simultaneously, is presented and mathematical analyses with other rate scheduling schemes, which provide efficiency criterion of transmission delay for rate scheduling schemes, are performed. Numerical results show the analyses explicitly.
Sung Kyung KIM Meejoung KIM Chung Gu KANG
Emerging requirements for higher rate data services and better spectrum efficiency are the main issues of third-generation mobile radio systems. In particular, a new concept of burst switching has been introduced for supporting the packet data services in the CDMA-based wireless system. In the burst switching system, radio resources are allocated to users for the duration of data bursts, which is a series of packets, as opposed to the conventional packet switching scheme. To implement the burst switching scheme, three different states (active, control hold, dormant states) are defined and two transition timers are employed to release the fundamental and supplemental code channels, respectively, at certain instances. Furthermore, the system is subject to burst admission control policy, with which a burst is admitted only when the number of currently available channels is greater than the admission threshold. Since there exists a trade-off between the additional packet access delay during a burst and resource utilization depending on the time-out value of the transition timer and burst admission threshold, it is critical to understand the performance characteristics in terms of the underlying design parameters. In this paper, we develop an analytic model and present a Quasi-Birth-Death (QBD) queueing analysis for evaluating the performance of burst switching schemes. This work focuses on the trade-off studies for optimizing the time-out value of the transition timer so as to minimize the average delay performance. Theoretical performance measures are derived by means of the matrix geometric method and furthermore, some simulation results are presented to validate the proposed analytical approach.
Yongsun KIM Meejoung KIM Wooyong LEE Chul-Hee KANG
This letter considers power-controlled transmission from directional antennas in mmWave wireless personal area network (WPAN) systems. The attributes of these systems are studied; these include the number of concurrent transmissions and the power consumption with different system parameters, such as the antenna's beamwidth and radiating efficiency. Numerical results are presented to show that the power controlled transmission enables more concurrent transmissions than the non-power controlled transmission. The results also show that the number of concurrent transmissions increases as the beamwidth and the path loss component become smaller and the antenna's radiating efficiency increases. In addition, the power controlled system generally uses less power than the non-power controlled transmission set up; the overall analysis is verified by simulation.