TDD Carrier Synchronization for Interference Reduction
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Solution Overview
Problem
In LTE-based wireless communication systems, adjacent carriers using different frame configurations for uplink and downlink transmissions cause severe interference, leading to a reduction in spectral efficiency due to the need for large guard bands, especially when multiple network operators share the same frequency band.
Innovation Solution
Synchronizing multiple carriers used by different apparatuses in Time Division Duplexing (TDD) systems, with a predetermined number of subframes reserved for specific transmission directions, and allowing the rest to be allocated flexibly for downlink or uplink, reducing cross-link interference and eliminating the need for large guard bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different frame configurations are used on adjacent carriers to allow flexibility in uplink and downlink sub frames, then adaptability is improved, but cross-link interference increases requiring larger guard bands which reduces spectral efficiency
Solution Approach 1:
The patent applies homogeneity by ensuring that corresponding sub frames across multiple carriers have the same transmission direction (all downlink or all uplink). This uniformity in transmission direction across synchronized carriers eliminates cross-link interference while preserving the ability to configure different frame structures, thus maintaining adaptability without sacrificing spectral efficiency
Solution Approach 2:
The patent creates equipotential conditions by synchronizing the frame structures across multiple carriers so that sub frames with the same index have identical transmission directions. This synchronization ensures that interference conditions are balanced and predictable across carriers, allowing flexible configuration without requiring additional guard bands that would reduce spectral efficiency
2Reliability
If larger guard bands are used to tackle interference between adjacent carriers with different frame configurations, then reliability is improved, but spectral efficiency deteriorates
Solution Approach 1:
The patent extracts the source of interference by synchronizing frame configurations across carriers, specifically aligning sub frame transmission directions. This removes the need for guard bands against cross-link interference, maintaining reliability through synchronized interference-free operation while preserving spectral efficiency by eliminating wasted guard band resources
Data Source
AI summary
Apparatus and method for communication are provided. The apparatus includes a controller for controlling the transmission and reception of data on one or more carriers utilizing Time Division Duplexing and frames including sub frames, where multiple carriers utilized by different apparatuses are synchronized with each other and a predetermined number of sub frames of each frame are reserved for predetermined transmission directions and a scheduler for allocating the rest of the sub frames carrier specifically either in downlink or uplink direction.