27.5-29.5 GHz Switched Array Sounder for Dynamic Channel Characterization: Design, Implementation and Measurements

Abstract

A pre-requisite for the design of wireless systems is the understanding of the propagation channel.While a wealth of propagation knowledge exists for bands below 6 GHz, the same can not be said for bands approaching millimeter-wave frequencies. In this paper, we present the design, implementation and measurement-based verification of a re-configurable 27.5-29.5 GHz channel sounder for measuring dynamic directional channels. Based on the switched array principle, our design is capable of characterizing 128×256 dual-polarized channels with snapshot times of around 600 ms. This is in sharp contrast to measurement times on the order of tens-of-minutes with rotating horn antenna sounders. Our design lends itself to high angular resolution at both link ends with calibrated antenna arrays sampled at 2 • and 5 • intervals in the azimuth and elevation domains. This is complemented with a bandwidth of up to 2 GHz, enabling nanosecond-level delay resolution. The short measurement times and stable radio frequency design facilitates real-time processing and averaging of the received wavefronts to gain measurement signal-to-noise ratio and dynamic range. After disclosing the sounder design and implementation, we demonstrate its capabilities by presenting dynamic and static measurements at 28 GHz over a 1 GHz bandwidth in an office corridor environment.

Virtual Antenna Array With Directional Antennas for Millimeter-Wave Channel Characterization

“…However, this method typically suffers from high side-lobes and limited steering range. Switch arrays [18], [19], i.e., different physical antenna elements are connected via an electronic switch to a single RF chain can be an option to make a compromise between cost and measurement duration. Appropriate array processing technique is required to achieve high angular resolution for switch arrays.…”