Sub Tiling - a flexible CSI Reference Signal Concept for 5G New Radio Systems

Mobile cellular radio systems have to support a multitude of user end devices with varying channel characteristics, ranging from static sensors over nomadic up to high speed users on roads or highways. The channel characteristics of these devices vary accordingly from being highly frequency selective in non line of sight scenarios to highly time variant on motor highways. Covering all these use cases simultaneously by a single reference signal pattern, conventionally, leads to a high overhead for reference signals as it requires a dense grid of pilot signals, fulfilling the sampling theorem in time and in frequency. In 5G new radio (NR) standardization, sub band specific pilot patterns are being proposed and discussed. Here, we suggest as alternative solution a so called sub tiling concept, which provides inherent flexibility for an either dense in time or in frequency channel estimation. That way, simultaneously nomadic users with frequency selective non line of sight channels can be supported from the same pilot pattern as fast moving users with relatively frequency flat radio channels.