Multi-Channel Random Access in Unlicensed Bands
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently utilizing unlicensed bands due to congestion and delays in the random access process, particularly in 5G communication systems, where the random access process and DL HARQ feedback transmission are often performed in a single carrier, leading to communication delays and reduced reliability.
Innovation Solution
The proposed method involves using multiple channels in a wireless communication system supporting an unlicensed band, employing listen-before-talk (LBT) for transmitting random access preambles and responses, and dynamically selecting control channels based on priority and availability to ensure successful communication, even when some channels are congested.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple channels are used for random access in unlicensed band, then communication reliability is improved, but device complexity increases
Solution Approach 1:
The patent divides the random access process into multiple independent channels (first control channel and second control channel), allowing UEs to attempt access through different channels simultaneously. This segmentation reduces the impact of congestion on any single channel and improves overall communication reliability.
Solution Approach 2:
The patent introduces an additional dimension for random access by utilizing multiple control channels with different priority levels. UEs can select channels based on priority requirements, adding a dimensional aspect to the random access process that enhances reliability without significantly increasing device complexity.
2Reliability
If listen-before-talk is performed on multiple control channels, then access success rate is improved, but transmission delay increases
Solution Approach 1:
The patent implements dynamic channel selection where UEs can adaptively choose between first and second control channels based on current channel conditions and priority requirements. The base station dynamically assigns UEs to different channels, allowing the system to respond to changing conditions and minimize delays while maintaining high access success rates.
Solution Approach 2:
The patent performs preliminary LBT assessments on multiple control channels before actual transmission. By evaluating channel availability in advance and selecting the most suitable channel, the system reduces the likelihood of transmission failures and retransmissions, thereby minimizing overall transmission delay.
3Speed
If high priority channels are allocated for random access, then access speed is improved, but channel congestion increases
Solution Approach 1:
The patent assigns different quality characteristics to different control channels by implementing priority-based channel allocation. High priority UEs are directed to specific channels optimized for fast access, while other channels handle regular traffic. This local differentiation of channel qualities allows fast access for priority traffic without causing widespread congestion across all channels.
Solution Approach 2:
The base station acts as an intermediary that manages channel allocation between UEs with different priority requirements. It assigns UEs to appropriate control channels based on their priority levels, mediating the conflict between fast access needs and congestion prevention by distributing traffic across multiple channels with different characteristics.
Data Source
AI summary
A communication method using a plurality of channels in a wireless communication system supporting an unlicensed band. The communication method includes: performing listen-before-talk (LBT) for transmitting a random access preamble on each of a plurality of control channels supported by a user equipment (UE), from among a plurality of control channels supported by a base station; transmitting a random access preamble through a control channel where the LBT succeeded from among the plurality of control channels where the LBT for transmitting the random access preamble is performed; and receiving a random access response (RAR) through a control channel determined according to a result of the LBT performed by the base station, from among the plurality of control channels supported by the UE, wherein a control channel is a channel through which a control signal and a data signal are transmitted and received.