Spectral efficiency of signal processing radios in interference limited environments: Array processing, MIMO, and MUD

Abstract

Radio networks using array processing or Single-Input Multiple-Output (SIMO); Multiple-Input Multiple-Output (MIMO) with and without Channel State Information (CSI) feedback; and Multi-User Detection (MUD) were all compared to baseline Single-Input Single-Output (SISO) networks to estimate possible improvements to area-spectral-efficiency. Two scenarios were investigated, a Mobile Ad-Hoc Network (MANET) with random interference transmitter locations, and Air-to-Ground (ATG) links with interference located on a grid. Radio propagation was subject to both Rice fading and log-normal shadowing with loss coefficients that increased with range. Substantial improvements were observed in the MANET scenario, by factors of 10 to 34 when link reliability was 90%, SIMO and MIMO radios used four-element arrays, and MUD signals had 12 dB processing gain. Smaller but still significant gains by factors of 2 to 6 were observed in the ATG scenario, where link reliability was 99%. Differences between MANET and ATG were attributed to a lower limit on interference range and reduced propagation variability in the ATG scenario.