Base Station DCI Mapping for Licensed-Unlicensed Band Coexistence
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Solution Overview
Problem
In wireless communication systems using licensed and unlicensed frequency bands, it is challenging for base stations to efficiently map and transmit downlink control information (DCI) due to the uncertainty of data allocation on the unlicensed band until Listen Before Talk (LBT) results are obtained, leading to potential data collisions and the need for high-performance hardware, which increases costs.
Innovation Solution
The system employs a configuration with separate L-band and U-band receivers and transmitters, along with a U-band vacancy determining unit that periodically checks for availability, allowing for simultaneous mapping of DCI to different frequency resources in the EPDCCH area, enabling efficient transmission even when the U-band is initially unavailable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If DCI mapping is performed in advance for both L-band and U-band, then transmission efficiency is improved, but data collisions occur when U-band is unavailable due to LBT failure
Solution Approach 1:
The patent segments the DCI mapping process into two distinct parts: L-band DCI mapping which is performed in advance, and U-band DCI mapping which is conditionally performed only after successful LBT. This segmentation allows the system to maintain high transmission efficiency for licensed band while avoiding waste and potential collisions on unlicensed band resources.
Solution Approach 2:
The patent introduces dynamic adaptability to the DCI mapping process by making U-band mapping conditional on LBT results. The system dynamically adjusts its behavior based on real-time channel availability, transitioning between static pre-mapping and conditional mapping modes to optimize both efficiency and reliability.
2Reliability
If high-performance hardware is used for real-time DCI mapping, then data collision is prevented, but device complexity and cost increase
Solution Approach 1:
The patent applies preliminary action by performing L-band DCI mapping in advance before LBT execution. This allows the base station to prepare control information for the licensed band without waiting for channel availability decisions, reducing the need for high-performance real-time processing hardware while maintaining reliable transmission.
Solution Approach 2:
The patent effectively uses a simpler, more economical approach for U-band DCI mapping by making it conditional rather than permanent. Instead of investing in expensive high-performance hardware for real-time mapping, the system uses a lightweight conditional mapping mechanism that activates only when needed, reducing overall device complexity and cost.
3Reliability
If U-band DCI is mapped only after LBT success, then data collision is avoided, but transmission delay increases
Solution Approach 1:
The patent segments the control information transmission into two independent paths: L-band transmission with advance DCI mapping that ensures no delay, and U-band transmission with conditional DCI mapping that avoids collisions. This segmentation allows the system to maintain low latency for critical licensed band communication while safely utilizing unlicensed band resources when available.
Solution Approach 2:
The patent makes the base station multi-functional by enabling it to operate effectively in both licensed and unlicensed bands with appropriate DCI mapping strategies for each. The system universally supports both transmission modes, using advance mapping for L-band and conditional mapping for U-band, thereby optimizing performance across different network conditions without sacrificing reliability.
Data Source
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AI summary
A base station apparatus (100) includes a first mapping unit (111) that maps first control information concerning a first frequency band in which no interference with communications in other wireless communication systems occurs, a second mapping unit (110) that maps second control information concerning a second frequency band in which interference with communications in other wireless communication systems possibly occurs, a generator (112) that generates a control channel signal by arranging the first control information and the second control information in areas different from each other, and transmitters (117, 118) that transmit the control channel signal generated by the generator (112) to a terminal device (200).