Byongkwon Moon

Optimizing uplink TCP-ACK transmission in WiMAZ OFDMA systems

In WiMAX networks, a bandwidth request-grant process is required for uplink operation. However, the process is not optimized for TCP, since the uplink ACK stream is disrupted due to the following: (a) The process consists of several stages which in turn introduce big transmission delay; and (b) it requires additional uplink bandwidth which is significant compared to the ACK packet size. In this paper, the authors propose a new ACK transmission scheme, where ACK packets are combined with a bandwidth request (BR) header. Through simulation, it is demonstrated that the proposed scheme reduces the overheads of TCP-ACK transmissions effectively.

Priority-based dynamic bandwidth allocation in Ethernet Passive Optical Networks

In this article, new Dynamic Bandwidth Allocation (DBA) algorithms which give high priority to some ONUs corresponding to important agencies are studied in order to manage emergency cases causing severe network traffic. In order to deal with such cases, the network state is divided into two states, namely the normal and the emergency states. We apply the Weighted Round Robin (WRR)-based algorithm to the normal state, and three priority-based DBA algorithms are applied to the emergency state. These algorithms are different from each other according to the mode of protecting non-priority ONUs from starving. Each algorithm is analyzed in terms of utilization of the uplink bandwidth and the average packet delay. Simulation and theoretical results show that the proposed algorithms are working properly at the emergency state and can satisfy more stringent QoS requirements than WRR algorithms.

Hierarchical Ethernet-PON Design with QoS Supporting by Eligible Reporting

Ethernet passive optical network (EPON) can be seen as a hierarchical service model. In this respect, it should have a proper media access control (MAC) protocol to allocate bandwidth effectively and fairly among ONUs. Moreover, it should be able to support quality of service (QoS) on a per-queue basis. To address these issues, we develop a dynamic bandwidth allocation (DBA) scheme and a scheduling algorithm called eligible reporting. The eligible reporting is composed of a simple rate-controller and the priority reporting. It endows EPON with the ability to support priority service in the sense that delay and bandwidth allocations are decoupled. Also, our DBA scheme achieves high network utilization in the weighted max-min fair sense. Simulation results are presented to evaluate the proposed algorithm

Distributed IPTV system for personal broadcasting service

In this paper, we propose a distributed IPTV system by which each program provider (PP) possess a light-weight software-based IPTV head-end station, and subscribers watch an aggregated IPTV channel. In the proposed system, 1) each media belongs to the distributed PPs is automatically streamed at a scheduled instance; 2) each streamed media can be aggregated in real-time according to scheduling information, and delivered to subscribers in the form of a single IPTV channel.

A Flow Control Algorithm Achieving Application Level Fairness

Most proposed system objectives such as max-min fairness or proportional fairness are based on the bandwidth of application. However, satisfaction of end users may not be proportional to the bandwidth itself. In this paper, we propose a simple algorithm to achieve so called utility max-min fairness, in which all users can achieve fairness in the application level not in the bandwidth level. Our algorithm is based on XCP and we modified the end user side slightly but not the router side for the sake of scalability. We showed the performance of our algorithm with simulations.