Adapting CCA Thresholds for IMD Mitigation in Carrier Aggregation
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Solution Overview
Problem
Existing solutions for mitigating inter-carrier interference due to intermodulation distortion in wireless networks, particularly in LTE systems using carrier aggregation, are inadequate when dealing with different types of carriers, as they do not effectively address harmonic distortion and intermodulation distortion across licensed and unlicensed spectrum usage.
Innovation Solution
Implementing carrier-type dependent algorithms in user equipment (UE) and network nodes that adapt transmission parameters and medium access control strategies, such as reducing power or restricting transmissions based on listen-before-talk (LBT) failures, to mitigate interference between component carriers operating in licensed and unlicensed frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carrier aggregation is used to increase transmission capacity in unlicensed spectrum, then additional spectrum usage possibility is provided, but intermodulation distortion and harmonic distortion cause inter-carrier interference
Solution Approach 1:
The patent changes transmission parameters (power levels, resource block allocations, modulation schemes) based on the type of carrier (licensed vs unlicensed) to mitigate intermodulation distortion. Different parameter sets are applied to different component carriers to reduce harmful interference while maintaining transmission capacity.
Solution Approach 2:
The patent applies different transmission qualities and configurations to different component carriers based on their specific characteristics (licensed vs unlicensed). Each carrier receives tailored power control, resource allocation, and modulation settings appropriate to its spectrum type, reducing overall inter-carrier interference.
2Reliability
If listen-before-talk procedure is applied in unlicensed spectrum, then fair spectrum sharing is achieved, but transmission delays occur when channel is busy
Solution Approach 1:
The patent performs preliminary actions by conducting LBT procedures and determining channel availability before actual data transmission. This allows the system to prepare transmission configurations in advance and avoid last-minute delays, while still maintaining fair spectrum sharing through proper LBT implementation.
3Object-affected harmful factors
If different transmitter configurations are selected based on LBT results, then intermodulation distortion is mitigated, but device complexity increases
Solution Approach 1:
The patent implements dynamic transmitter configuration selection based on real-time LBT results and carrier type. The system can switch between different transmission modes (full power, reduced power, different resource allocations) depending on channel conditions and spectrum type, effectively managing intermodulation distortion through adaptive behavior rather than static complex configuration.
Data Source
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AI summary
A method by a first node of a telecommunications system, includes determining a parameter defining harmonic distortion and/or inter-modulation distortion (IMD) on a second type of carrier due to transmission of signals on a first type of carrier. The method adapts at least one of a signal measurement and a clear channel assessment (CCA) threshold used for performing a CCA procedure on the second type of carrier for deciding whether to transmit a signal or not on the second type of carrier, based on the parameter. The method performs the CCA procedure on the second type of carrier using the adapted at least one of the signal measurement and the CCA threshold to decide whether to transmit a signal or not on the second type of carrier.