Enhancing VoIP in UTRAN LTE Downlink: Methods and Performance

Yong FAN  Mikko VALKAMA  

IEICE TRANSACTIONS on Communications   Vol.E94-B   No.8   pp.2338-2345
Publication Date: 2011/08/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E94.B.2338
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
VoIP,  E-UTRA,  LTE,  OFDMA,  system level performance,  

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In this article, we study different methods to enhance the capacity of Voice-over-IP (VoIP) in Evolved UTRAN (E-UTRAN) downlink. According to previous E-UTRAN system level simulation results, VoIP capacity with dynamic scheduling and semi-persistent scheduling is limited by available Physical Downlink Control CHannel (PDCCH) resources and Physical Downlink Shared CHannel (PDSCH) resources respectively. The different behavior of these two packet scheduling schemes and specific bottleneck on capacity lead us to formulate two distinctly different performance enhancement strategies, which are the main focus of this paper. For dynamic scheduling, we propose a bi-directional power control algorithm to rationalize PDCCH resource allocation, thus greatly improving VoIP capacity. For semi-persistent scheduling, we introduce Adaptive Transmission Bandwidth (ATB) to rationalize PDSCH resource allocation and further apply dynamic packet bundling in highly-loaded network, thus improving VoIP capacity in a considerable manner. The proposed enhancement methods are validated through large-scale system level simulations and the obtained system simulation results further confirm effectiveness of these enhancement methods.