On the Role of Downlink Control Information in the Provision of QoS for NRT Services in LTE

The provision of Quality of Service (QoS) to users of LTE networks depends to a large degree on the choice of an appropriate scheduling algorithm able to meet the requirements of mobile operators. Dynamic packet scheduling has been recognized as a key approach to maximize the utility of OFDMA-based systems due to its inherent ability to exploit the frequency selectiveness of wideband channels both in time and frequency domain. However, one of the main issues associated to dynamic scheduling is the high amount of signaling overhead required to provide users with resource allocation information. While the impact of control channel limitations on LTE VoIP capacity has been widely studied yet, tradeoffs associated to control channel usage and the provision of QoS for Non-Real Time (NRT) services has been basically omitted in current literature. In this paper, such tradeoffs have been addressed from several perspectives. Results show that the relationship between scheduling policies, offered levels of QoS (expressed in terms of guaranteed bit rates) and control channels capacity is not trivial and requires careful planning.