Base Station Uplink Throughput via Licensed Assisted Access
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Solution Overview
Problem
In licensed assisted access (LAA) wireless communication systems, if the unlicensed band is busy and a terminal does not receive a reservation signal in time for uplink transmission, it cancels the transmission, leading to reduced data throughput.
Innovation Solution
A base station uses a dedicated licensed band and a shared unlicensed band for communication, transmitting control signals to specify resources for data transmission, determining if the shared band is idle or busy, and sending permission signals to allow transmission when idle, with an offset indicating the start time for the terminal's data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the base station transmits a reservation signal in the unlicensed band before uplink transmission, then the terminal can perform UL transmission using the unlicensed band, but if the unlicensed band is busy and the reservation signal is not received in time, the terminal cancels the transmission causing throughput reduction
Solution Approach 1:
The base station performs LBT and transmits a reservation signal in advance before the terminal's UL transmission timing. This preliminary action reserves the unlicensed band for the terminal, ensuring that when the terminal transmits, the band is already secured and ready for use, thereby preventing transmission cancellation and maintaining throughput.
Solution Approach 2:
The base station continuously monitors the unlicensed band status and provides feedback through reservation signals. When the band becomes idle, the base station transmits the reservation signal to inform the terminal that the band is now available for UL transmission, enabling dynamic adaptation to changing band conditions and preventing unnecessary transmission cancellations.
2Reliability
If the base station performs LBT and waits for the unlicensed band to be idle before transmitting the reservation signal, then the band can be used cleanly, but this waiting period delays the terminal's UL transmission timing
Solution Approach 1:
The base station performs LBT and transmits the reservation signal as early as possible once the band is detected as idle, rather than waiting until the exact UL transmission moment. This preliminary reservation action secures the band in advance, allowing the terminal to proceed with transmission without further delays while ensuring clean band usage.
Solution Approach 2:
The system dynamically adjusts the reservation signal transmission timing based on real-time band status. When the band transitions from busy to idle, the base station immediately transmits the reservation signal, optimizing the balance between ensuring clean band usage and minimizing transmission delays according to actual environmental conditions.
Data Source
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AI summary
According to one embodiment, a base station (20) includes a licensed band transmitting unit (220), a determining unit (205), and an unlicensed band transmitting unit (210). The licensed band transmitting unit (220) transmits, to a terminal, a control signal for specifying a resource in a shared band to be used for data transmission by the terminal. The determining unit (205) determines whether the resource in the shared band is idle or busy. The unlicensed band transmitting unit (210) transmits a permission signal for permitting transmission in the shared band when the determining unit (205) determines that the resource in the shared band is idle. The control signal or the permission signal includes an offset indicating a time from the permission signal to a start of transmission of data from the terminal to the base station (20) with reference to the permission signal transmitted from the unlicensed band transmitting unit (210).