Digital Frequency Converter for TDD Wireless Systems
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In TDD wireless communication systems using carrier aggregation, the switching of PLL frequencies between receive and transmit slots causes significant performance degradation due to the long switching duration, especially when the center frequencies of the received and sent signals differ.
Innovation Solution
A wireless communication apparatus that includes a local oscillator circuit, a radio frequency transmitter, and a digital frequency converter, where the digital frequency converter compensates for the frequency difference between the center frequencies of the received and sent signals, allowing the local oscillator signal frequency to remain unchanged, thereby avoiding data transmission interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the PLL switches the frequency of the output LO signal between receive slot and transmit slot, then the local oscillator signals for receiver and transmitter can be provided, but the communication performance is degraded due to long switching duration
Solution Approach 1:
The patent divides the frequency adjustment function into two independent parts: the PLL maintains a stable reference frequency while the digital frequency converter handles frequency differences. This segmentation allows the PLL to remain stable during switching while the digital converter compensates for frequency variations, resolving the contradiction between frequency adaptation and communication performance.
Solution Approach 2:
The patent replaces the mechanical PLL frequency switching mechanism with a digital frequency conversion approach. Instead of physically switching the PLL output frequency between slots, the system uses a digital frequency converter to adjust frequencies in the digital domain, eliminating the long switching duration and maintaining communication performance.
2Adaptability or versatility
If the PLL switches frequency between receive and transmit slots, then different center frequencies can be supported, but data transmission is interrupted during switching
Solution Approach 1:
The patent ensures continuous data transmission by making the frequency adjustment process transparent to the data stream. The digital frequency converter operates continuously without interrupting the data flow, maintaining the continuity of useful action while supporting different center frequencies for receive and transmit slots.
Solution Approach 2:
The digital frequency converter acts as an intermediary between the stable PLL output and the required varying frequencies. It mediates the frequency differences between receive and transmit slots without requiring direct PLL switching, thereby eliminating data transmission interruptions.
3Adaptability or versatility
If the PLL outputs LO signals of different frequencies for receive and transmit slots, then the bandwidth difference condition can be met, but the switching duration is long causing performance degradation
Solution Approach 1:
The patent introduces dynamic frequency adjustment capability through the digital frequency converter, allowing the system to adapt to different bandwidth conditions in real-time without physical switching. This dynamic approach eliminates the long switching duration while maintaining the ability to compensate for bandwidth differences between receive and transmit slots.
Data Source
AI summary
A wireless communication method and apparatus, and a radio frequency subsystem are provided. The apparatus includes a local oscillator circuit, configured to provide a local oscillator signal; a radio frequency transmitter coupled to the local oscillator circuit, configured to send a first signal on a first carrier based on the local oscillator signal provided by the local oscillator circuit; a radio frequency receiver coupled to the local oscillator circuit, configured to receive a second signal on a second carrier based on a local oscillator signal of a same frequency as the local oscillator signal provided by the local oscillator circuit; and a digital frequency converter coupled to the radio frequency transmitter and the radio frequency receiver, configured to provide a digital frequency conversion operation to compensate for a frequency difference between a center frequency of the first carrier and a center frequency of the second carrier.