Evaluation and Improvement of VoIP Capacity for LTE

Abstract:
LTE-Advanced (LTE-A) proposed by the 3rd Generation Partnership Project (3GPP) has been accepted by the International Telecommunication Union (ITU) in 2010 as an IMT-Advanced (IMT-A) compliant 4G mobile radio system. Besides high spectral efficiency for data services, LTE-A had to prove its capability to support a large number of voice calls through Voice over IP (VoIP). Radio resource management for many VoIP calls continuously switching between active and inactive state is challenging. Control channel limitations prevent the dynamic scheduling of every VoIP connection in each 1 ms subframe. Semi-persistent scheduling enables channel quality aware scheduling accounting for control channel limitations. We describe and evaluate by simulation five semi-persistent radio resource assignment algorithms focusing on boosting uplink VoIP capacity. Results show that high capacity gains are achieved under smart resource assignment strategies.