Time-Domain Spatial Signal Processor for Wideband Beamforming
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Solution Overview
Problem
Current multi-antenna receivers face challenges in beam-squinting and limited interference rejection due to frequency-dependent phase-shift approximations, leading to increased dynamic range requirements for ADCs and power consumption, especially when handling wide modulated bandwidths.
Innovation Solution
An N-element baseband time-domain spatial signal processor using cascaded voltage-to-time converters for true-time delay alignment and Kronecker decomposition for independent interference cancellation, reducing ADC requirements and power consumption while enabling beamforming, beam-nulling, and multiple interference filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If phase-shift elements are used to approximate time-delay in multi-antenna receivers, then device complexity is reduced, but beam-squinting occurs and bandwidth is limited
Solution Approach 1:
The patent replaces phase-shift elements (electrical/RF domain components) with time-domain processing circuits operating on baseband signals. This substitution moves the time-delay function from the RF front-end to the baseband processing stage, enabling true-time-delay (TTD) implementation that is frequency-independent and avoids beam-squinting while maintaining device complexity at acceptable levels through integrated circuit implementation.
Solution Approach 2:
The patent changes the operating domain from RF phase-shifting to baseband time-domain processing. By converting received RF signals to baseband and performing spatial signal processing in the time domain, the system achieves frequency-uniform processing across wide bandwidths, eliminating the frequency-dependent beam-squinting characteristic of phase-shift approaches.
2Loss of information
If digital-domain TTD spatial signal processing is implemented after digitizing all channels, then complete signal access is achieved, but power consumption increases due to power-hungry ADCs
Solution Approach 1:
The patent performs spatial signal processing (beamforming, beam-nulling, interference cancellation) in the baseband time-domain before analog-to-digital conversion. By completing the spatial processing operations on continuous-time baseband signals, the system eliminates the need for multiple high-resolution ADCs, thereby significantly reducing power consumption while maintaining complete signal information access for the processed outputs.
Solution Approach 2:
The patent extracts and processes only the necessary spatial signal components in the baseband domain before conversion to digital. By performing TTD-based spatial processing on continuous-time signals and converting only the final processed outputs to digital, the system avoids the power consumption of digitizing all intermediate channel signals while preserving complete information access for the spatially processed results.
3Device complexity
If phase-shifter-based arrays are used for beam-nulling, then device complexity is reduced, but interference rejection capability is limited
Solution Approach 1:
The patent replaces phase-shifter-based beam-nulling with time-domain spatial processing using TTD circuits. This substitution enables frequency-independent null placement by accurately aligning time delays across wide bandwidths, achieving superior interference rejection for wideband interferers while maintaining device complexity through integrated circuit implementation of TTD elements.
Solution Approach 2:
The patent implements dynamic time-delay adjustment in the baseband domain to achieve frequency-uniform beam-nulling. By using TTD circuits that provide accurate time alignment across the entire bandwidth, the system dynamically adapts the null placement to maintain deep rejection of wideband interference, overcoming the static and frequency-dependent limitations of phase-shifter-based approaches.
4Device complexity
If wide modulated bandwidths are handled with phase-shift approximation, then device complexity is reduced, but dynamic range requirements for ADCs increase
Solution Approach 1:
The patent changes the processing domain to baseband time-domain, where wideband signals are processed with TTD circuits that provide frequency-independent time alignment. This parameter change eliminates the need for high dynamic range ADCs because the spatial processing is completed on continuous-time signals, and only the final processed outputs require digitization, thereby reducing measurement precision requirements while maintaining wide bandwidth capability.
Data Source
AI summary
An N-element baseband (BB) time-domain spatial signal processor system and methodology for large modulated bandwidth multi-antenna receivers are provided. Such a processor generally includes a pipeline converter configured as an asynchronous time-to-digital converter, wherein the asynchronous time-to-digital converter arrangement generates a residue value and an asynchronous pulse and is further arranged to amplify the residue value so as to result in an amplified residue value; and a 2-bit flash time-to-digital-converter configured to quantize the amplified residue value. Thus, a true-time delay spatial signal processing system and technique in the time-domain that enables beamforming, beam-nulling and multiple independent interference cancellation after time-alignment of signals using cascaded voltage-to-time converters and quantization using relaxed pipeline time-to-digital converters is presented.