System Level Modeling and Optimization of the LTE Downlink

6. Summary and Outlook6. Summary and Outlook6.1. SummaryIn this thesis, an accurate, low-complexity link-to-system model for 3GPP LTERelease 8 is presented. The model is based on a ZF linear receiver and separates thelink abstraction procedures into a link quality model and a link performance model.The link quality model outputs a per-subcarrier post-equalization SINR, which thelink performance model compresses via MIESM to an AWGN-equivalent SINR valueand is then mapped to BLER by means of link-level-generated curves.Based one the presented L2S model, a complete LTE system level simulation hasbeen built, which also integrates the network layout (pathloss, shadow fading,eNodeB and UE placement), as well as a Winner Phase II channel model andappropriate MIMO feedback. This allows for performance evaluation of differentscheduling algorithms and interference coordination schemes such as FFR.In Chapter 3, the post-equalization SINR for each of the LTE transmit modes isderived and combined with all of the parameters characterizing an LTE networkdeployment. An extended correlation matrix for generation of spatially-correlatedshadow fading generation is also applied. As for the same correlation distance, asmaller pixel resolution in the pathloss maps requires of more neighbors for thespatial correlation computation, the applied extended correlation matrix increasesthe accuracy of the shadow fading maps in cases where more resolution is needed.For configurations of up to 4×4, the accuracy of the model is validated against linklevel simulations, confirming the accuracy of the L2S model in single- and multi-cellsimulation scenarios.Employing the maximum LTE channel bandwidth of 20 MHz, significant gains insimulation run-time are introduced by employing the presented link abstraction81