Accuracy vs. complexity trade-off in simulations of future wireless networks

As wireless networks shift towards denser deployments, simulations take longer time to run and consume more resources. Simulation of the physical (PHY) layer is particularly time consuming and, as such, its implementation requires the use of abstracted models with low computational complexity, in order to provide accurate results in reasonable time. Although Mutual Information Effective SINR Mapping (MIESM) is commonly used as the standard method to abstract the PHY layer, the popular "modified Shannon´s equation" - proposed by Mogensen et al. - has been gaining ground as a simpler and lighter implementation of the PHY layer in System Level (SL) simulations. This paper aims at comparing MIESM and the modified Shannon´s formula for SL simulators in terms of accuracy and computational complexity. Results show that Shannon´s method proves beneficial for networks with a large number of users, as it is less complex and allows us to reduce up to 30 times the simulation time required by the PHY layer abstraction. On the other hand, the accuracy is in the range of 80-87% for the instantaneous throughput compared to MIESM; the accuracy improves up to 95% for the time-averaged user throughput. In scenarios involving fast-varying channels, the modified Shannon´s formula needs to be calibrated considering the actual user speed; in this case, accuracy of 90% can be achieved for a user speed of 60kmph.