LBT Method Selection for LTE Wi-Fi Coexistence
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for Licensed-Assisted Access (LAA) LTE in unlicensed spectrum face issues with inappropriate delays and interference, leading to poor performance in wireless communications networks due to inadequate Listen-Before-Talk (LBT) procedures, which result in starvation and collisions with Wi-Fi devices.
Innovation Solution
A method where a first radio node in an LTE wireless communications network selects an LBT method based on the type of information to be transmitted, deferring data transmission until the channel is idle and allowing immediate transmission of control or management information, thereby prioritizing these and reducing collisions with Wi-Fi ACK/NACK transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LAA LTE performs LBT procedure in unlicensed spectrum, then coexistence with Wi-Fi is improved, but transmission delays and collisions occur leading to poor network performance
Solution Approach 1:
The patent changes the LBT procedure parameters by introducing different observation duration values (first observation duration for data, second observation duration for control information) and different deferral behaviors. This allows the system to adapt transmission parameters dynamically based on information type, improving both coexistence and performance by avoiding excessive delays for control information while maintaining fair sharing for data transmissions.
Solution Approach 2:
The patent implements dynamic LBT behavior where the radio node selectively applies different LBT methods based on the type of information to be transmitted. Control information triggers immediate transmission after a shorter observation period, while data information triggers deferred transmission after a longer observation period. This dynamic adaptation resolves the contradiction by optimizing performance for different traffic types simultaneously.
2Object-affected harmful factors
If LAA LTE defers transmission until channel is idle, then collisions with Wi-Fi are reduced, but starvation occurs leading to transmission delays
Solution Approach 1:
The patent applies different LBT strictness levels to different information types. Control information receives preferential treatment with shorter observation durations and immediate transmission permission, while data information undergoes more stringent LBT with longer observation durations and deferral requirements. This local differentiation reduces overall transmission delays for critical information while maintaining collision avoidance for data transmissions.
Solution Approach 2:
The patent segments the LBT procedure into two distinct paths: one for control information with minimal deferral and one for data information with extended deferral. This segmentation allows the system to handle time-sensitive control traffic separately from best-effort data traffic, reducing starvation effects for control information while still providing collision protection for data transmissions.
3Adaptability or versatility
If LAA LTE uses standard LBT procedure, then fair sharing of unlicensed spectrum is achieved, but control and management information transmission is delayed
Solution Approach 1:
The patent introduces dynamic LBT parameter selection based on information type. Control information triggers a dynamic response that bypasses the standard lengthy LBT procedure, using instead a shortened observation period followed by immediate transmission. Data information continues to follow the standard fair-sharing LBT procedure. This dynamic differentiation maintains fair spectrum sharing while accelerating control information transmission.
Solution Approach 2:
The patent changes the observation duration parameter from a fixed standard value to a variable value that depends on information type. Control information uses a second (shorter) observation duration, while data information uses a first (longer) observation duration. This parameter change enables faster control information transmission while preserving fair sharing characteristics for data transmissions.
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A method performed by a first radio node (101) to select (1401) an LBT method based on a type of information to be transmitted in a radio channel (142) in unlicensed spectrum. The first radio node (101) performs (1402) an LBT with the selected LBT method. When the information is data, the method comprises always deferring (1502) transmission until: A) after completion of a first period of observation, an outcome of at least a second period of observation is that the channel (142) is idle, or B) an outcome of a first period and one or more defer periods is that the channel (142) is idle. When the information is control or management information, the selected method comprises allowing transmission immediately after an outcome of the first period is that the channel (142) is idle. A duration of the first period provides priority to the control or management information over data.