Base Station Timing Adaptation for Unlicensed Band Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
LTE-A systems face instability in communication when another system occupies the unlicensed band, and even when using white spaces, there is a risk of interference from other systems, leading to unreliable data transmission.
Innovation Solution
A base station apparatus and terminal device configuration that uses a second frequency band different from the primary band for communication, with mechanisms to detect and adapt to other systems' usage, ensuring stable communication by adjusting transmission and reception timing and using carrier sense mechanisms to avoid collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the LTE-A system uses unlicensed band or white space for communication, then spectral efficiency and data rate are improved, but communication stability deteriorates due to interference from other systems
Solution Approach 1:
The base station performs carrier sense detection before transmitting data to determine if the unlicensed band is occupied by other systems. This preliminary action allows the system to detect potential interference conditions and adjust transmission timing accordingly, preventing collisions and maintaining communication stability while enabling the use of unlicensed bands for improved data rates
Solution Approach 2:
The system dynamically adjusts the reception timing of ACK/NACK signals based on carrier sense results. When another system is detected occupying the unlicensed band, the base station flexibly changes the timing to receive ACK/NACK after the other system's communication ends. This dynamic adaptation resolves the contradiction by allowing high data rates when the band is free while maintaining reliability when interference is present
2Ease of operation
If the base station transmits data at fixed timing, then transmission simplicity is maintained, but communication reliability deteriorates when another system occupies the band
Solution Approach 1:
The base station implements dynamic timing adjustment for receiving ACK/NACK signals based on carrier sense outcomes. The reception timing is changed flexibly to occur after other systems' communication ends in the unlicensed band, maintaining transmission simplicity in the licensed band while improving reliability in the unlicensed band through adaptive timing
3Reliability
If the system uses carrier sense to detect other systems, then communication stability is improved, but device complexity increases
Solution Approach 1:
The base station performs carrier sense detection as a preliminary step before data transmission to check if the unlicensed band is occupied. This simple detection mechanism provides sufficient information to adjust transmission timing, improving communication stability without introducing excessive system complexity
Solution Approach 2:
The system changes the timing parameter for receiving ACK/NACK signals based on carrier sense results. By adjusting only the reception timing parameter rather than implementing complex interference mitigation techniques, the system achieves improved reliability with minimal increase in device complexity
Data Source
AI summary
In an LTE-A system, there is a problem that it is difficult to perform stable communication in a case where there is a time when another system occupies an unlicensed band being used. There is provided a base station apparatus that communicates with a terminal device in a second frequency band different from a first frequency band capable of being used as a dedicated frequency band. The base station apparatus includes: a wireless transmission unit that transmits data or control information to the terminal device; and a wireless reception unit that receives data or control information transmitted from the terminal device. The wireless transmission unit transmits data to the terminal device, and the wireless reception unit performs a process of receiving ACK/NACK transmitted from the terminal device in a subframe of an initial uplink after communication of another system is ended in a case where the other system performs the communication in the second frequency band at a reception timing of the ACK/NACK of the data transmission.