All-Digital Wideband Beamformer With 2D Beamfilters
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Solution Overview
Problem
Current digital beamformers for massive MIMO systems with large phased arrays face challenges in scalability and cost due to high digital complexity and resource occupation, particularly in achieving wideband operation beyond the 25 MHz bandwidth of current all-digital phased arrays.
Innovation Solution
The development of an all-digital transmitter and wideband beamformer based on 2-D space-time filter network theory, which reduces hardware complexity and cost by shifting RF components into the digital domain, utilizing digital upconversion, and replacing analog power amplifiers with digitally switched-mode power amplifiers, integrated with multi-core 2D network-resonant digital plane wave beamfilters and delta-sigma modulators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional digital beamformers are implemented element-wise on FPGA or ASIC for massive MIMO systems, then flexibility and electronic beam steering capability are improved, but hardware complexity and cost increase significantly
Solution Approach 1:
The patent segments the beamforming function into multiple independent beamforming units, each handling a specific beam direction. This allows the system to achieve flexible electronic beam steering through software configuration of individual units rather than complex hardware reconfiguration, thereby reducing overall hardware complexity while maintaining adaptability.
Solution Approach 2:
The patent designs a universal beamforming unit that can be configured to generate beams in different directions through software programming. This multi-functional unit replaces the need for dedicated hardware for each beam direction, significantly reducing hardware complexity while maintaining the ability to steer beams electronically to multiple users simultaneously.
2Reliability
If the number of antenna elements is increased to provide better SNR and serve more users in 5G systems, then communication performance is improved, but scalability and cost worsen due to traditional digital beamforming architecture
Solution Approach 1:
The patent divides the large phased array into multiple smaller beamforming units, each capable of independent operation. This segmentation allows the system to scale by adding more units rather than increasing the complexity of a single unit, making it easier to accommodate more antenna elements while maintaining scalability and managing cost effectively.
Solution Approach 2:
The patent transitions from a two-dimensional array structure to a three-dimensional architecture by stacking multiple beamforming units in the vertical dimension. This dimensional change allows the system to increase antenna elements and improve SNR while maintaining scalability through modular addition of units rather than expanding the footprint in the horizontal plane.
3Adaptability or versatility
If current all-digital phased array architecture is used, then digital beamforming capability is achieved, but bandwidth is limited to 25 MHz
Solution Approach 1:
The patent implements dynamic frequency compensation mechanisms within each beamforming unit that allow the system to adapt to different frequency ranges. This dynamic adjustment capability enables the beamformer to maintain performance across a wider bandwidth (at least 25% FBW) by automatically compensating for frequency-dependent phase and amplitude variations, thereby increasing productivity without sacrificing digital beamforming capability.
Data Source
AI summary
An all-digital transmitter (ADT) is provided. The ADS includes a baseband interface configured to store and transmit an (baseband) input signal at a corresponding frequency band, a polyphase finite impulse response filter configured to receive and convert the baseband input signal into different phases, a digital upconverter configured to upconvert each of the different phase baseband input signal to a predetermined carrier frequency in a digital domain, a set of multi-core 2-dimensional network-resonant digital plane wave beamfilters, wherein each of the multi-core 2D NR-DPW beamfilters is configured to transmit the upconverted baseband input signal by a target angle, a multi-core delta-sigma modulator configured to encode the upconverted input signal into pulsating signals, and a serializer configured to serialize the encoded pulsating signals into a RF bitstream.