Youngwoong Kim

A novel adaptive routing scheme for the QoS-based multimedia services in mobile ad-hoc networks

A mobile ad-hoc network is composed of only mobile nodes, which are distributed dynamically, without any wired backbone or centralized entities. Since the existing works on ad-hoc routing protocol are mostly biased toward a military application, we need a new routing scheme for the support of multimedia services in mobile ad-hoc networks. Therefore, we propose a novel scheme that can support a variety of traffic attributes and can be applicable to high-speed and multimedia data services in mobile ad-hoc networks by using adaptive transmission power level. As a result of simulation, the proposed scheme has better performance than conventional method, which is performed with uniform transmission power level, in view of route query delay time.

A new routing scheme based on the terminal mobility in mobile ad-hoc networks

A mobile ad-hoc network is composed of only mobile nodes, which are distributed dynamically, without any wired backbone or centralized entities. Each terminal in the mobile ad-hoc network also has the role of the router, but the frequent changes of the terminal positions induce a waste of time, energy and computing power for updating the routing table with the paging, and also may provoke a call dropping. To overcome this problem, we propose a new routing scheme based on the terminal mobility in mobile ad-hoc networks. In the proposed scheme, terminals are classified into low-mobility terminals and high-mobility terminals. To prevent the frequent update of the routing table, only the low-mobility terminal can be the routing terminal in the proposed scheme. The performances of the proposed scheme and conventional scheme are simulated. The numerical results show that the mean call dropping time in the proposed scheme are much lower than that in the other conventional schemes.

Radio resource assignment for multimedia services in multiple-chip-rate DS/CDMA systems

This paper is concerned with radio resource allocation in multiple-chip-rate (MCR) DS/CDMA systems accommodating multimedia services with different information rates and quality requirements. Considering power spectral density (PSD) over a radio frequency (RF) band and the effect of RF input filtering on the receiver in MCR-DS/CDMA systems, we present criteria for capacity estimation and clarify the characteristics of subsystems. The system performance in MCR-DS/CDMA systems is strongly affected by radio resource assignment. A minimum power-increment-based resource assignment scheme and a random-based resource assignment scheme are proposed. The performance of both schemes are compared in terms of blocking probability and normalized throughput. The minimum power-increment-based resource assignment scheme yields a better performance than the random-based resource assignment scheme for multimedia services.