Impact of dynamic control format indicator on downlink throughput performance in LTE system

Abstract

This paper presents an integrated study of dynamic control format indicator impact on downlink throughput in Long Term Evolution (LTE) network based on number of users and configured system bandwidth. CFI (Control Format Indicator) is an indicator notifying number of OFDM symbols used for carrying PDCCH (Physical Downlink Control Channel) at each subframe. CFI can be configured in Static and dynamic modes. Static CFI uses fixed number of OFDM symbols for the control channels in a subframe, while in Dynamic CFI symbol value is computed at every sub frame based on the total number of DCI (Downlink Control Information) grants. An End-to-End LTE testing environment is built by using real User Equipment (UE) and LTE core network for capturing and analyzing the throughput impact due to dynamic CFI across configured system bandwidths. Experimentation is carried out for comparing the downlink throughput of the system with Static and Dynamic CFI modes. A novel study has been conducted on downlink throughput for TCP and UDP traffic in different LTE bandwidths. The study shows that system performance in terms of Downlink (DL) throughput has drastically improved by using Dynamic CFI in LTE network.