Wideband Inter-beam Interference Cancellation for mmW/Sub-THz Phased Arrays With Squint
As relative bandwidth increases, beam squint, i.e., frequency dependent directivity, limits the wideband performance of phase-shifter steered arrays. This effect is already notable in 5G systems operating at 28 GHz and above with 400/800 MHz bandwidths, especially if broadband cancellation is needed between multiple beams. The wideband squinting effect reduces the signal-to-interference-plus-noise-ratio of a multibeam system by changing the level and direction of the spatial null towards the interferer. This paper examines the effectiveness of the inter-beam interference (IBI) cancellation using crosscoupled signals for wideband arrays with visible squint effect. For a large relative bandwidth of the array, this paper presents a component carrier-based approach for interference cancellation between the beams of different users or data streams. Furthermore, as bandwidth and array size increase, the impact of squint increases, which is also examined for the cancellation of the IBI. Furthermore, an example scenario is simulated using standard 5GNR modulated waveforms.