Mobile Device Front End Architecture for TDD Spectrum Reuse
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Solution Overview
Problem
Current radio communication systems face limitations in data capacity due to fixed bandwidths in Frequency Division Duplex (FDD) spectra, especially as data traffic increases, and existing technologies do not effectively utilize the frequency spectrum for Time Division Duplex (TDD) applications without interference.
Innovation Solution
The implementation of a switching circuit that reallocates FDD spectrum for TDD applications using filters and switches to route both FDD and TDD signals within the same frequency band, employing duplex filters, bandpass filters, and surface acoustic wave (SAW) or film bulk acoustic resonator (FBAR) filters to optimize signal transmission and reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If FDD spectrum is used with fixed bandwidth allocation, then simultaneous two-way communication is achieved, but data capacity is limited as data traffic increases
Solution Approach 1:
The patent implements dynamic spectrum allocation by enabling the system to switch between FDD and TDD modes based on traffic conditions. The front end module dynamically reconfigures the RF path to accommodate different duplexing schemes, allowing the spectrum to be adaptively reallocated from fixed FDD bandwidth to flexible TDD bandwidth to meet increasing data capacity demands.
Solution Approach 2:
The front end module is designed with multi-functionality to support both FDD and TDD operations using the same hardware components. The switching circuit and filter bank can be reconfigured to handle different signal paths, enabling a single device to serve multiple duplexing modes and thereby improving spectrum utilization efficiency.
2Productivity
If FDD spectrum is re-allocated for TDD applications, then spectral efficiency is enhanced, but signal interference between FDD and TDD signals may occur
Solution Approach 1:
The patent segments the RF signal path into separate processing chains for FDD and TDD signals. By using independent filtering and switching paths, the system can process FDD receive signals and TDD receive signals separately, preventing interference between the two duplexing modes while allowing spectral reuse.
Solution Approach 2:
The patent introduces filter banks as intermediary components between the antenna and receiver circuitry. These filters act as mediators that selectively pass FDD or TDD signals while blocking the other, thereby enabling spectral sharing between FDD and TDD applications without causing harmful interference.
3Reliability
If filter banks are used to route FDD and TDD signals, then signal separation is achieved, but device complexity increases
Solution Approach 1:
The patent combines multiple filtering functions into a single filter bank structure that can be reconfigured for different signal types. By merging the FDD filter and TDD filter into one shared filter bank with switching control, the system achieves signal separation while reducing the total number of discrete filter components required.
Solution Approach 2:
The switching circuit operates periodically to route signals through appropriate filter paths based on the active duplexing mode. This periodic switching action allows the same hardware components to be reused for different signal types at different times, reducing overall device complexity while maintaining reliable signal separation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances spectral efficiency by allowing more receive spectrum to be used, compatible with existing FDD spectral outlays, and dynamically allocates guard bands to minimize interference, thereby improving network capacity and bandwidth utilization.
Implementation Method 1
a duplex filter configured to filter an FDD receive signal
Implementation Method 2
a first filter configured to filter a TDD receive signal
Implementation Method 3
a plurality of switches configured to route the FDD receive signal from an antenna through the duplex filter to receiver circuitry
Implementation Method 4
to route the TDD receive signal from the antenna through the first filter to the receiver circuitry
Implementation Method 5
the duplex filter includes a surface acoustic wave (SAW) filter
Data Source
AI summary
A switching circuit for use in a frequency division duplex (FDD) spectrum re-allocated for time division duplex (TDD) applications comprises a first filter configured to filter a TDD receive signal, a duplex filter configured to filter an FDD receive signal, and a plurality of switches configured to route the FDD receive signal from an antenna through the duplex filter to receiver circuitry and to route the TDD receive signal from the antenna through the first filter to the receiver circuitry such that the FDD and TDD receive signals share the FDD spectrum.