A Novel LIPA Scheme for LTE VoIP Services with Home eNBs

The need for wireless multimedia communication motivates the development of the 4G cellular wireless networks. To this end, the 4G standard, Long Term Evolution (LTE), is specified by the 3GPP. Especially, the local IP access (LIPA) function has been defined for a home base station (HeNB) to offload traffic from the core network as otherwise packets are always routed through the packet data network gateway which is located at the back-end side. Without the LIPA function, the packet routing in an LTE network is in a detour way, even if in the communication between two user equipments (UEs) attaching to the same HeNB. To implement the LIPA function, two solutions have been proposed in the literature. However, they still suffer from a few shortcomings. In this paper, we propose a novel solution, in which an additional bearer is responsible for local data packet detection and, once detected, is transformed into a data bearer for local data packet delivery. Qualitative analysis distinguishes our solution from the two previous solutions in several aspects. Simulation results show that our method outperforms the two solutions in terms of packet transmission delay and mean opinion score (MOS). An extension is proposed to provide local IP access for UEs attaching to different serving HeNBs which are yet in the same domain. Analytical results shows that applying the extension, the domain edge router can provide hundreds of VoIP connections with the local IP access service, which is ten times more than the two solutions in the literature can do.