System-level performance of the MIMO-OFDM downlink with dense small cell overlays

Multi-tier heterogeneous networks based on MIMO-OFDM are a promising approach to enhance coverage and capacity in next generation cellular networks. We investigate the downlink performance of such a small cell deployment based on a system-level model of a 4G network. The parameters are based on 3GPPs latest long term evolution (LTE) standard. The co-existence of a set of Macrocells with a dense small cell deployment is modelled by using statistical channel models. Since all cells operate on the same frequency as in a single frequency network (SFN), the system is interference limited. First, the number of small cell nodes operated in a Macro cell-of-interest is increased, in order to evaluate the effect of small cell densification on the Macro cell as well as on the overall performance. Next, mechanisms are introduced which allow enhanced inter-cell interference coordination (eICIC). The trade-off by introducing such coordination techniques is shown by evaluating physical layer (PHY) system throughput results.