Dynamic Random Access Resource Allocation in Unlicensed Bands
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Solution Overview
Problem
In wireless communication systems using LTE technology, random access in unlicensed bands is challenging due to shared frequency usage with other wireless communication systems, leading to difficulties in adaptively arranging sub-frames and resources for preamble transmission, which affects frequency usage efficiency.
Innovation Solution
A terminal device and base station device system that dynamically allocates random access resources based on reception timing and LBT processes, allowing for flexible preamble transmission timing and adaptive sub-frame arrangement according to traffic demand, using a processor to manage RA resources and LBT processing units for efficient unlicensed band usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resources for transmission of a preamble are periodically arranged as in LTE, then random access can be conducted in licensed bands, but it is difficult to arrange LAA sub-frames in unlicensed bands when the band is being used by other wireless communication systems
Solution Approach 1:
The patent applies dynamics by making the sub-frame arrangement adaptive rather than fixed. The base station dynamically determines sub-frame configurations based on LBT results and traffic conditions, allowing the system to switch between different sub-frame patterns (e.g., all downlink, all uplink, or mixed) to optimize unlicensed band usage while ensuring random access reliability.
Solution Approach 2:
The patent changes the parameter of sub-frame timing arrangement from a fixed periodic pattern to a dynamic pattern determined by LBT outcomes. The base station notifies terminal devices of the determined sub-frame arrangement through signaling, allowing the system to adapt transmission timing parameters based on real-time unlicensed band availability.
2Ease of operation
If resources for transmission of a preamble are periodically arranged, then random access procedure can be simplified, but frequency usage efficiency in unlicensed bands is decreased due to inability to adaptively arrange sub-frames
Solution Approach 1:
The system maintains operational simplicity through dynamic adaptation by having the base station automatically determine optimal sub-frame arrangements based on LBT results and notify terminal devices via signaling. This removes the need for complex terminal-side decisions while achieving high frequency usage efficiency through adaptive sub-frame configuration.
Solution Approach 2:
The patent implements feedback mechanisms where the base station monitors LBT results and traffic conditions, then adjusts sub-frame arrangements accordingly and notifies terminal devices. This feedback loop enables the system to optimize frequency usage efficiency while keeping the random access procedure simple for terminal devices.
3Object-affected harmful factors
If LBT is conducted in unlicensed bands, then equitability with other wireless communication systems is ensured, but resources for transmission of a preamble cannot be arranged in a flexible manner
Solution Approach 1:
The patent applies preliminary action by performing LBT before arranging sub-frames and preamble resources. The base station conducts LBT in advance, determines the outcome, and then configures appropriate sub-frame arrangements and random access resources based on the LBT result, ensuring both equitability and flexibility.
Solution Approach 2:
The system changes resource arrangement parameters dynamically based on LBT outcomes. When LBT succeeds, the base station can arrange sub-frames and preamble resources flexibly; when LBT fails or the band is occupied, it adjusts the arrangement to avoid interference, maintaining equitability while preserving flexibility.
Data Source
AI summary
A terminal device includes a processor and a memory connected to the processor, wherein the processor executes a process including: receiving a resource specifying signal that specifies a random access resource used to transmit a preamble for random access; selecting one preamble from a plurality of preamble candidates previously acquired; and transmitting the selected preamble by using a random access resource arranged in timing based on a reception timing of the resource specifying signal.