Listen-Before-Talk Operation in LAA with Freeze Intervals
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Solution Overview
Problem
Current Listen-Before-Talk (LBT) procedures in wireless communication networks, particularly in mobile telecommunications, often lead to unfair access and increased collisions among nodes competing for unlicensed spectrum carriers, resulting in degraded throughput.
Innovation Solution
Implementing a method that defines a pre-defined time structure for carrier access, including a freeze interval and a Listen-Before-Talk procedure, to ensure fair and predictable access to carriers, especially in systems with multiple nodes competing for access, using a radio node that performs Clear Channel Assessments and adjusts LBT parameters based on operation conditions and collision rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LBT procedure is used for carrier access in unlicensed spectrum, then channel access fairness is improved, but access predictability and throughput are degraded
Solution Approach 1:
The patent introduces a periodic structure with freeze intervals and transmission intervals. During freeze intervals, LBT procedures are suspended and carriers are not accessed, creating regular periodic gaps. Transmission intervals are when carriers can be accessed. This periodic structure makes carrier access predictable while maintaining fairness through the systematic alternation between freeze and transmission periods.
Solution Approach 2:
The patent dynamically adjusts LBT parameters including the duration of freeze intervals, transmission intervals, and backoff window sizes based on observed collision rates and channel conditions. This dynamic adaptation allows the system to optimize between fairness and predictability by adjusting the balance between LBT procedure enforcement and transmission opportunities based on real-time network conditions.
2Reliability
If random backoff is implemented to reduce collisions, then channel access fairness is improved, but access predictability and throughput are degraded
Solution Approach 1:
By introducing periodic freeze intervals where no LBT procedures occur, the system creates predictable transmission opportunities during transmission intervals. This reduces the need for extensive random backoff periods while maintaining fairness, as all nodes know when transmission opportunities will occur based on the periodic structure.
Solution Approach 2:
The patent changes the backoff window size parameter dynamically based on collision rates. When collisions are detected, the backoff window is increased to reduce future collisions. When collisions decrease, the window is reduced to improve throughput. This adaptive parameter adjustment resolves the contradiction between fairness (requiring larger backoff windows) and throughput (requiring smaller backoff windows).
Data Source
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AI summary
There is disclosed a method for operating a radio node for a wireless communication network, the radio node being adapted for transmitting communication data on at least one carrier based on a timing relative to a pre-defined time structure. The method comprises defining at least one freeze interval relative to the pre-defined time structure, performing a Listen-Before-Talk, LBT, procedure to determine whether accessing the at least one carrier for transmission is allowed, and, if accessing the at least one carrier for transmission is determined to be allowed based on performing the LBT procedure, starting transmission of communication data on the at least one carrier outside the at least one freeze interval. There are also disclosed a corresponding node, system, program product and storage medium.