SBFD Communication Reference Chain for Uplink Interference Cancellation
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Solution Overview
Problem
Existing 5G TDD networks face significant uplink coverage issues due to interference between uplink and downlink signals in sub band full duplex (SBFD) communication systems, leading to congestion in the uplink receive channel and reduced coverage.
Innovation Solution
A sub band full duplex communication system utilizing separate transmit and receive antenna arrays with a reference chain for linear cancellation processing to reduce interference, employing a digital predistortion (DPD), digital-to-analog converter (DAC), frequency mixer, power amplifier (PA), circulator, filter, and antenna arrays, along with a coupler, frequency mixer, and analog-to-digital converter (ADC) to collect and cancel self-interference components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sub band full duplex technology is implemented to improve uplink coverage, then uplink resources can be flexibly configured and uplink delay can be reduced, but downlink transmission interferes with uplink reception causing congestion in uplink receive channel
Solution Approach 1:
The patent divides the frequency spectrum into multiple sub-bands, allowing different sub-bands to be used for uplink and downlink transmissions simultaneously. This segmentation enables frequency division duplexing at the sub-band level, improving uplink coverage while managing interference through selective frequency allocation.
Solution Approach 2:
The patent introduces self-interference cancellation (SIC) technology as an intermediary mechanism to eliminate the harmful effect of downlink transmission on uplink reception. By using reference signals and cancellation algorithms, the system mediates the interference between simultaneous uplink and downlink transmissions in the same sub-band.
2Productivity
If uplink and downlink transmissions are performed in the same slot to reduce delay, then productivity improves, but mutual impact between uplink and downlink causes congestion in uplink receive channel
Solution Approach 1:
The patent enables continuous transmission by allowing uplink and downlink to occur simultaneously in the same time slot through sub-band frequency division. This eliminates idle time between transmissions and maintains continuous useful action, improving overall system productivity while managing interference through frequency separation.
Solution Approach 2:
The patent segments the frequency domain into multiple sub-bands, allowing simultaneous uplink and downlink transmissions in different sub-bands within the same time slot. This segmentation enables full-duplex operation that improves productivity while the referenced SIC technology eliminates residual interference.
3Object-affected harmful factors
If separate transmit and receive antenna arrays are used to improve isolation, then device complexity increases, but interference reduction is achieved
Solution Approach 1:
The patent separates transmit and receive functions into different antenna arrays, creating physical isolation between transmitting and receiving elements. This segmentation improves interference reduction while the system manages the increased complexity through coordinated beamforming and signal processing techniques.
Data Source
AI summary
This disclosure provides a communication system comprising a first branch and a second branch. The first branch includes a transmit chain and a reference chain. The transmit chain includes a DPD, a DAC, a frequency mixer, a power amplifier (PA), a circulator, a filter, and a first antenna array that are sequentially connected. The second branch includes a receive chain comprising a second antenna array, a low noise amplifier, a frequency mixer, and an ADC that are sequentially connected. In an SBFD slot, the transmit chain is configured to perform downlink radio frequency transmission on a baseband signal; the receive chain is configured to perform uplink radio frequency transmission on a radio signal; and the reference chain collects a radio frequency signal output by the PA, uses the radio frequency signal as a reference signal, and performs linear cancellation processing on a received signal output by the receive chain.