Make yourself at home : A comparative study of VoLTE Roaming architectures

Abstract: While the data traffic has increased through the years, the average revenue per user (ARPU) remains flat. Thus, mobile network operators need to find a solution for how to support the growing amounts of traffic at fixed revenue per user. Similarly, the number of roaming users has increased, but according to recent European Union (EU) regulations, mobile network operators have to lower their charges for roaming to zero by June 2017. While this decrease in roaming charges will benefit European roaming users, mobile network operators have to cover their expenses for their own roaming subscribers, thus they have to find a way to lower their operational expenses (OPEX). Additionally, it is important for operators to consider how they might actually benefit from the removal of roaming charges. This project will focus on roaming in 4th generation (4G) mobile networks. A common roaming scenario would include three different networks: the Home Public Land Mobile Network (HPLMN) a transit network, and a Visited Public Land Mobile Network (VPLMN). Normally, both the signaling traffic and the media payloads traverse these networks, thus causing additional latencies and increasing OPEX. However, in recent years, a new mechanism, called local breakout (LBO), was introduced that can lower the costs of roaming and avoid unnecessary traffic while meeting a roaming user's needs. The goal of LBO is to decrease the operator's OPEX when supporting roaming subscribers. A secondary goal of LBO is to reduce the latencies experienced by roaming subscribers during their sessions. Achieving both of these goals will satisfy both operators and consumers. This thesis project analyzes Voice over Long Term Evolution roaming with the aim of presenting the various alternative architectures for Voice over LTE roaming, compare them in different scenarios, and evaluating them based on criteria defined during this project. The conclusion is that the best solution that is applicable to all the mobile network operators for all the possible roaming scenarios does not exist yet. The various VoLTE roaming architectures can be chosen by the mobile network providers according to their needs.