Kun-Min Yeo

A packet scheduler with forward equilibrium and adaptive fair selection method in wireless multimedia traffic environment

In this paper, a self-adaptive algorithm of a packet scheduler is addressed as a crucial method of high-speed transmission of multimedia traffic in a shared wireless link, in accordance with new architectural functions. In the slot budget that is updated sequentially in the order of priorities of applications and sessions, adaptive modulation and coding options are considered to take into account radio links subject to fading and interference. The dedicated local packet scheduler that is in control of each type of application employs an application-sensitive scheduling algorithm. For real-time scheduler, the forward-equilibrium algorithm is introduced to consider the future state of delay. When it comes to non real-time scheduler, the adaptive-fair-selection algorithm is developed to provide the fairness between sessions. The global packet scheduler manages the overall operation of the dedicated local packet schedulers and supervises the slot budget in each transmission-time-interval making a final decision. The scheduler can provide the local fairness between sessions in each service class. Related to the bounds on delay, real-time sessions can be served with predefined requirements at the cost of increased packet dropping rates. Implementation complexity is thought to be simple, providing a low-complexity algorithm in the local scheduler for the nonreal-time class.

Estimating handover rate in heterogeneous mobility and cell types

This paper provides a general analytic method to estimate the handover rate in mobile packet systems with heterogeneous cell types and multimedia services. The handover rate is derived as a closed-form function of the Laplace transform of the session time distribution. The proposed model can be easily extended to analyze the mobility feature of the heterogeneous mobile systems with hierarchical cell structure.

A Query-Based Resource Request Scheme for Wireless Packet Communications

This paper presents a simple query-based uplink scheduling scheme in wireless packet systems to provide QoS of uplink multimedia traffic. The query timer in base station controls the periodicity of resource request which is normally realized by frequent random accesses in demand-based resource request schemes. It is shown that the scheme dramatically reduces the number of random accesses by 90% on average, as compared to the demand-based resource request scheme, with similar performance in packet delay, MAC (medium access control) overhead.