Impact of AMR-WB Codec on VoLTE Call Blocking in Cellular LTE Network

In Voice over LTE (VoLTE), speech is transmitted over packet-switched network. It is often observed that calls get blocked while initiating or during handoff. This Quality of Service (QoS) measure depends on available amount of radio resources within a cell in the Long Term Evolution (LTE) network. Third Generation Partnership Project (3GPP) recommends use of Adaptive Multi-Rate Wideband (AMR-WB) codec for better voice quality in the LTE network offering VoLTE service. The AMR-WB voice codec with varying bit rates may require different amount of radio resources at physical layer. This may affect to the call blocking performance in an LTE network. In this paper, we have proposed a Physical Resource Block (PRB) based model using the concept of Markov Chain to investigate the VoLTE call blocking performance in the LTE network. We have presented the impact of AMR-WB voice codec with different bit rates on call blocking in an LTE network providing VoLTE service.