VoIP jitter in 3GPP long term evolution networks

3GPP LTE is the next step towards 4G mobile communications with performance comparable to wire-line networks. Careful planning and design must be carried out to assure a successful deployment for both, users and network operators. LTE must be able to adapt to a variety of traffic such as data, voice, and video. Services currently provided through circuit-switched systems are expected to have a similar equivalent in LTE, an all-IP based network. Voice is the most widespread service and represents the main revenue for network operators. Users expect at least the same Quality of Service provided by CS networks while operators look for an increase in capacity and reduction of costs. Such objectives can be reached through Voice-over-IP (VoIP). This service has the following characteristics: Bursty low bitrate traffic, strict packet delay-based QoS, and a high number of simultaneous users. Furthermore, VoIP is highly sensible to jitter. Jitter is a common issue in packet-switched networks, where packets arrive at random times at the receiver. For voice services, it implies disruptions in speech intelligibility and poor QoS. This master thesis studies the jitter phenomenon for the LTE downlink, where bottlenecks arise naturally due to user queues, when it is operated under VoIP traffic. Specifically, the impact on jitter due to network congestion, retransmissions and different modulation and coding schemes, for diverse radio channel conditions, are analyzed.