Grant: Alliance Grants

Emerging communication systems, including 5G and beyond cellular systems will use different frequencies for the mobile user to communicate with the base station in one direction and for the base station to communicate with the mobile user in the other direction. The difference between these frequencies makes the estimation of one channel from the other one, which is crucial for effective communication, a challenging task. The goal of our research proposal is to develop a technique for inferring the characteristics of the base station-to-mobile channel from those of the mobile-to-base station channel ones, despite the different frequencies on which these channels operate. To perform this task, we will rely on the fact that the so-called angular power spectrum~(APS), which describes the way in which electromagnetic power is distributed around a sphere, is relatively insensitive to frequency variations. Despite their relative insensitivity to frequency variations, APSs that are commonly encountered in practice are not conducive to channel estimation. For instance, APSs spanning a wide range of angles and with rugged profiles are difficult to use for channel estimation. To alleviate this difficulty, in this project, we will seek a method for manipulating the wireless channel in order for the underlying APS to possess desirable features. To do so, we will consider the use of intelligent reflective surfaces~(IRS), which are surfaces that modify the electromagnetic waves impinging on them before reflecting them. The number and positioning of IRSs and the way they are configured in order to achieve APSs with desirable characteristics is at the heart of this project. Using IRSs to shape the wireless channel will enable reliable, efficient and cost-effective communication between mobile entities and their serving base stations.