Mixed-Mode Millimeter-Wave Transmitter for Multi-Band SNR Control
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Solution Overview
Problem
Current wireless communication technologies face challenges in designing multi-band transmitters for contiguous and non-contiguous CA transmission, particularly at higher frequencies like 28GHz millimeter waves, due to issues with out-of-band noise, reduced Signal-to-Noise Ratio, and stringent sampling rate requirements, which hinder efficient and flexible radio frequency front-end design.
Innovation Solution
A mixed-mode millimeter-wave transmitter architecture that employs two-dimensional parallelization and hybrid digital-analog signal processing, using digital polyphase interpolation filters, oscillator banks, and pulse encoding techniques to reduce complexity and enhance frequency agility, allowing for efficient multi-band transmission while overcoming sampling rate limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If Digital UpConversion (DUC) is placed after pulse encoding to achieve multi-band transmission, then device complexity is reduced, but Signal-to-Noise Ratio deteriorates due to out-of-band noise distributed over the entire spectrum
Solution Approach 1:
The transmitter is divided into multiple parallel channels, each handling a specific frequency band with its own pulse encoder and DUC. This segmentation allows each channel to operate independently at lower sampling rates while maintaining overall system performance and SNR through selective band processing.
Solution Approach 2:
The patent transitions from a single-channel sequential architecture to a multi-channel parallel architecture, adding the dimension of frequency band separation. This enables simultaneous processing of multiple bands with optimized sampling rates for each, resolving the SNR-complexity tradeoff.
2Reliability
If sampling rate is increased to at least twice the carrier frequency to position DUC before pulse encoding, then Signal-to-Noise Ratio is improved, but device complexity and manufacturing difficulty increase significantly
Solution Approach 1:
The high sampling rate requirement is segmented across multiple parallel channels, each operating at a manageable sampling rate (at least twice its respective carrier frequency). This divides the overall high-rate processing into several lower-rate processing streams, reducing individual component complexity while maintaining SNR.
Solution Approach 2:
The patent changes the sampling rate parameter from a single high value to multiple lower values, each optimized for its specific frequency band. This parameter transformation allows each channel to meet the Nyquist criterion at a practical sampling rate rather than requiring an excessively high universal sampling rate.
3Adaptability or versatility
If integer multiples of modulators sampling frequencies are used to achieve multi-band transmission, then frequency agility is improved, but Signal-to-Noise Ratio decreases due to need to maintain integer multiplicity in sampling rates
Solution Approach 1:
Each frequency band is processed in a separate channel with its own independently optimized sampling rate. This segmentation removes the constraint of maintaining integer multiplicity across all bands, allowing each channel to achieve optimal SNR with sampling rates tailored to its specific frequency requirements.
Solution Approach 2:
The patent introduces dynamic sampling rate selection for each channel, allowing the system to adapt sampling rates to the specific requirements of each frequency band rather than being constrained by a fixed integer multiple relationship. This dynamic approach optimizes both frequency agility and SNR.
Data Source
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AI summary
A radio frequency (RF) transmitter includes a set of input ports to receive baseband samples of a signal to be transmitted on a set of disjoint frequency bands, a set of filter banks, there is one filter bank for each input port, each filter bank includes a plurality of digital polyphase interpolation filters to sample a shifted phase of the corresponding sequence of baseband samples and to interpolate the sampled phases to produce a plurality of sequences of interpolated baseband phased samples with the shifted phase, and a set of oscillators banks, each oscillator bank includes a plurality of polyphase Digital Direct Synthesizer (DDS) corresponding to the plurality of digital polyphase interpolation filters to generate a plurality of sequences of samples of digital waveform.