LTE Carrier Allocation in Shared Unlicensed Spectrum
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Solution Overview
Problem
Conventional wireless communication systems in shared unlicensed spectra face interference and performance degradation due to non-cooperative mobile technologies like LTE-U, which dominate spectrum access and disrupt coexistence with cooperative technologies like Wi-Fi, leading to asymmetrical usage and hardware changes that are costly and impractical for existing devices.
Innovation Solution
A method for allocating LTE carriers in the unlicensed 5 GHz band that scans and measures RF energy across contiguous channels, selecting the channel with the lowest power to avoid interfering with Wi-Fi transmissions, ensuring fair airtime usage and channel bonding compatibility, thereby allowing LTE and Wi-Fi to coexist without disrupting each other.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If LTE-U utilizes centralized spectrum access scheduling, then LTE throughput and efficiency are improved, but interference with Wi-Fi and other cooperative technologies increases
Solution Approach 1:
The system performs preliminary sensing of the unlicensed spectrum to detect Wi-Fi activity before LTE transmission. The eNodeB scans the target band to identify occupied channels and avoids allocating LTE carriers on channels where Wi-Fi is detected, preventing interference before it occurs
Solution Approach 2:
The patent introduces an intermediary sensing mechanism that acts as a mediator between LTE and Wi-Fi systems. The eNodeB uses RF energy detection to sense the presence of Wi-Fi signals and uses this information to make intelligent carrier allocation decisions, allowing both technologies to coexist fairly
2Quantity of substance
If LTE-U dominates spectrum access, then LTE airtime usage increases, but Wi-Fi performance and user experience degrade
Solution Approach 1:
The system applies partial action by allocating LTE carriers only on channels where Wi-Fi is not detected, rather than attempting to dominate all available spectrum. The eNodeB performs selective carrier allocation based on sensed conditions, using only the portion of spectrum that is currently available without displacing Wi-Fi
Solution Approach 2:
The system changes the parameter of carrier allocation from fixed/aggressive to dynamic/adaptive. The eNodeB continuously monitors RF energy levels and adjusts carrier allocation decisions based on real-time spectrum conditions, changing behavior from dominant to cooperative as needed
3Difficulty of detecting and measuring
If hardware changes are implemented in Wi-Fi devices to detect non-cooperative signals, then detection capability improves, but device cost and complexity increase
Solution Approach 1:
Instead of requiring Wi-Fi devices to implement complex detection hardware, the patent inverts the approach by having the LTE system (eNodeB) perform the sensing and detection functions. The LTE infrastructure scans for Wi-Fi activity and adapts its behavior accordingly, eliminating the need for hardware changes in Wi-Fi devices
Data Source
AI summary
A method for allocating aggressive signal carriers in a target band of a wireless communication network is provided. The network includes at least one long term evolution (LTE) node and at least one non-LTE transmission source. The target band includes at least two adjacent pairs of contiguous radio frequency (RF) channels. The method includes steps of scanning each contiguous RF channel of the target band to measure a respective value of non-LTE RF energy therein, determining, from the measured non-LTE RF energy, that a first one of the contiguous RF channels is occupied by a non-LTE carrier, and allocating an LTE carrier to a second one of the contiguous RF channels, different than the first one of the contiguous RF channels, based on the determination.