Hyun-Hwa Seo

Urgency and Efficiency based Packet Scheduling Algorithm for OFDMA wireless system

In this paper, we propose an urgency and efficiency based wireless packet scheduling (UEPS) algorithm that is able to schedule real time (RT) and non-real time (NRT) traffics at the same time. The UEPS algorithm is designed to support wireless downlink packet scheduling in OFDMA system which is a strong candidate wireless system for the next generation mobile communications. The UEPS algorithm uses the time-utility function as a scheduling urgency factor and the relative status of the current channel to the average one as an efficiency indicator of radio resource usage. The design goal of the UEPS algorithm is to maximize throughput of NRT traffics with satisfying QoS requirements of RT traffics. Simulation study shows that the UEPS algorithm is able to give better throughput performance than existing wireless packet scheduling algorithms such as proportional fair (PF) and modified-largest weighted delay first (M-LWDF) while satisfying QoS requirements of RT traffics such as the average delay and the packet loss rate under various traffic loads.

Urgency and efficiency based wireless downlink packet scheduling algorithm in OFDMA system

In this paper, we exploit how to provide quality of service at the downlink in the OFDMA wireless communication systems. The OFDMA, also referred to as multiuser-OFDM, is considered as a strong candidate wireless system for the next generation mobile communications. Since there are a variety of traffic demands for real-time and non-real-time traffics in the next generation mobile communications, especially at the downlink from a base station, scheduling of such downlink traffic packets is expected to be a key function for QoS provisioning to users. One such scheduling algorithm designed not only to support multiple users simultaneously but also to offer real-time and non-real-time services to a user at the same time is the urgency and efficiency based packet scheduling (UEPS) algorithm [S. Ryu et al., 2005]. The UEPS algorithm uses the time-utility function as a scheduling urgency factor and the relative status of the current channel to the average one as an efficiency indicator of radio resource usage. The design goal to maximize throughput of non-real-time traffics with satisfying QoS requirements of real-time traffics.

Traffic characteristics based performance analysis model for efficient random access in OFDMA-PHY system

Currently, IEEE 802.16a wireless MAN supports the contention based OFDMA-CDMA ranging subsystem for ranging operation (Initial Ranging, Periodic Ranging, Bandwidth Request)[1]. This system uses essentially the slotted ALOHA protocol. However, the number of code-slots/frame for random access transmission tends to be much greater than one and a simple Markov chain analysis may not be numerically feasible. At the same time, the frame size in number of code-slots may be dynamically adjusted based on the traffic load. In order to evaluate delay-throughput performance and stability measure of the random access protocol, we first examine the possible traffic load to be carried throughput the ranging subchannel. We the present performance analysis and numerical examples.

Design of performance analysis model for efficient random access protocol in CDMA based OFDMA-PHY system

Currently, IEEE 802.16a wireless MAN supports the contention based OFDMA-CDMA ranging subsystem for ranging operation (initial ranging, periodic ranging, bandwidth request). This system is basically similar to slotted ALOHA (K. Leonard and S.S. Lam, April 1975), but the frame size (code-slot/frame) allocated for random access or ranging request is relatively big and can be altered by the dynamic adjustment of downlink and uplink subframe size on the MAC frame of OFDMA-PHY system. In this paper, the design performance analytical model for correct interpretation of ranging subsystem is presented. Until now, the Internet traffic study have achieved wire net, but there is still a need for Internet traffic study that correctly reflects the radio environment. In this paper, the performance analysis result of this paper can perform the reference mark for random access protocol in OFDMA-CDMA ranging system. Traffic modeling can also be used to prepare the network resources in radio networks

Adaptive and qos downlink multimedia packet scheduling for broadband wireless systems

In this paper, we propose an adaptive urgency and efficiency based packet scheduling (A-UEPS) algorithm that is to designed to maximize throughput of non-real-time (NRT) traffics as long as QoS requirements of real-time (RT) traffics such as the packet delay and the loss rate requirements are satisfied. In addition, the A-UEPS algorithm provides trade-off between performance objectives of RT and NRT traffics adaptively by adjusting scheduling precedence of packets of RT and NRT traffics in accordance with the time-varying traffic situations such as the offered traffic load and traffic mix. Simulation study shows that A-UEPS algorithm results in efficient and adaptive scheduling performance under various traffic situations.