Map-Assisted Power Allocation and Constellation Design for mmWave WDM with OAM in Short-Range LOS Environment

Consider a system that integrates positioning and single-user millimeter wave (mmWave) communication, where the communication part adopts wavelength division multiplexing (WDM) and orbital angular momentum (OAM). This paper addresses the power allocation and high dimensional constellation design in short-range line-of-sight (LOS) environment, with stable communication links. We propose a map-assisted method to replace online estimation, feedback and computation with the look-up table searching. We explore the possibility of using a few patterns in the maps, and investigate the performance loss of using the optimal solution of one position for other positions. For power allocation, we first characterize the performance loss outside the OAM beam regions with only plane waves, and figure out that the loss is always small. However, in OAM beam regions, the performance loss has similar characteristics only at some specific positions. Based on numerical results, we illustrate that a few patterns can be adopted for all receiver locations in the map. We also investigate high dimensional constellation design, and prove that a fixed constellation can be adopted for the positions where the channel matrices are sufficiently close to be proportional. Similarly, we figure out that the constellation design for all receiver locations can be represented by a few constellation sets.