Spectrum Efficiency and Processing Latency Trade-offs in Panel-Based LIS

The next generation wireless systems will face stringent new requirements, including ultra-low latency, high data rates and enhanced reliability. Large Intelligent Surfaces, is one proposed solution that has the potential to solve these high demands. The real-life deployment of such systems involves different design considerations with non-trivial trade-offs. This paper investigates the trade-off between spectral efficiency and processing latency, considering different antenna distribution schemes and detection algorithms. A latency model for the physical layer processing has been developed with realistic hardware parameters. The simulation results using an in-door environment show that distributing the antennas throughout the scenario improves the overall reliability, while the impact on the latency is limited when zero-forcing (ZF) detection is used. On the other hand, changing the detection algorithm to maximum-ratio combining (MRC) may reduce the latency significantly, even if a larger number of antennas are needed to achieve a similar spectrum efficiency as ZF detection.