Youn Seon Jang

Dynamic GOP structure selection to support QoS in vertical handoff

This paper proposes a dynamic GOP structure selection method to provide seamless video streaming for vertical handoff in the heterogeneous wireless network. The proposed method dynamically changes the interval of I-pictures by using the received signal strength indication (RSSI) and the pilot strength (Ec/Io) in order to reduce error propagation due to packet losses. Thus, with the proposed method, the client can always receive the I-picture right after vertical handoff. Experimental results show that the proposed method can significantly reduce the video quality degradation caused by vertical handoff in the real-time video encoding applications.

Power-aware rate-control for QoS provisioning over CDMA networks

This paper presents a power-aware rate control method that dynamically adjusts the encoding bit rate according to the receiving power level of mobile stations (MSs) in CDMA network. The proposed rate-control method performs bit allocation at the video frame level using the estimated channel bit rate to minimize the average distortion over wireless video transmission. Experimental results show that the proposed method can significantly enhance the video quality in CDMA networks.

A fast adaptive power allocation for maximizing a discrete utility function of OFDMA system

In this paper, we propose a fast adaptive power allocation algorithm for an orthogonal frequency division multiple access (OFDMA) system that employs an adaptive modulation and coding (AMC) scheme to significantly reduce the processing time. We show that the proposed algorithm reduces the complexity by M -the number of AMC levels- times compared with greedy adaptive power allocation (APA) which is known as the optimal algorithm for power allocation problem while still maintaining the utility at the same level as greedy APA.