Fast Fallback Mechanism for mmWave Link Recovery
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Solution Overview
Problem
Millimeter wave (mmWave) wireless communication systems face challenges in maintaining efficient data communication and fast link recovery due to line of sight (LoS)/non-LoS transitions, leading to link failures and increased errors in legacy fallback procedures.
Innovation Solution
A method for fast fallback in mmWave systems involves a legacy base station receiving a fallback request from mmWave user equipment (UE), activating a fallback timer, and determining whether a second request is received within that time, allowing for timely fallback to prevent link failures and reduce channel measurement and reporting load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If fast fallback is implemented in mmWave systems, then link recovery speed is improved, but system complexity increases due to additional fallback request messages and timer management
Solution Approach 1:
The patent implements preliminary action by having the UE send a fallback request message to the legacy BS before the actual fallback occurs. The legacy BS activates a fallback timer upon receiving this message, preparing the system in advance for the fallback event. This allows the system to transition quickly when needed while maintaining structured control mechanisms.
Solution Approach 2:
The patent employs feedback mechanisms where the UE monitors the fallback timer status and the legacy BS receives feedback through the second fallback request message. The system continuously monitors link conditions and provides feedback loops that enable dynamic adjustment of fallback timing, balancing speed with controlled complexity.
2Measurement precision
If fallback timer is activated to determine fallback timing, then fallback accuracy is improved, but processing delay increases due to timer management and message waiting
Solution Approach 1:
The fallback timer is activated in advance when the legacy BS receives the first fallback request message, before the actual fallback decision is made. This preliminary activation allows the system to precisely measure the time window for receiving the second fallback request message, achieving accurate timing control without excessive delay during the actual fallback execution.
Solution Approach 2:
The patent implements a fast fallback mechanism where, upon receiving the second fallback request message within the timer window, the legacy BS immediately transmits the fallback command message without additional delays. This rushing through of the critical fallback decision process minimizes processing delay while maintaining timing accuracy through the pre-activated timer.
3Reliability
If fast fallback procedure is implemented, then link failure prevention is improved, but channel measurement and reporting load increases for mmWave UE
Solution Approach 1:
The patent extracts the channel measurement and reporting functions from the fast fallback procedure itself. Instead of requiring extensive channel measurements and reports during the fast fallback process, the system relies on the pre-configured fallback timer and simple message exchanges. This extraction reduces the measurement and reporting load while maintaining link failure prevention through the timer-based mechanism.
Solution Approach 2:
The legacy BS performs self-service by autonomously managing the fallback timer and making fallback decisions based on the received messages, without requiring extensive channel measurements or reports from the UE. This self-service approach reduces the burden on the UE while ensuring reliable link failure prevention through the BS's autonomous timer management.
4Reliability
If fallback timer value is set to cover LoS/NLoS transition time, then link recovery reliability is improved, but fallback response time increases due to longer timer duration
Solution Approach 1:
The patent implements parameter changes by dynamically adjusting the fallback timer value based on the specific LoS/NLoS transition conditions. The timer value is set to cover the expected transition time while allowing for propagation and processing delays. This parameter optimization ensures reliable link recovery by covering the necessary time window without excessively increasing the fallback response time.
Solution Approach 2:
The fallback timer is activated in advance with a pre-calculated value that accounts for LoS/NLoS transition time, propagation delay, and processing delay. This preliminary setup with an optimized timer value ensures that the system can reliably recover from link failures within the necessary time window without adding excessive response time during the actual fallback execution.
Data Source
AI summary
The present invention relates to a wireless access system supporting millimeter waves (mmWave) and provides methods for performing fast fallback so as to avoid link disconnections and devices for supporting same. The method whereby a legacy base station supports the fast fallback of a mmWave terminal in a wireless access system supporting millimeter waves (mmWave), according to one embodiment of the present invention, may comprise the steps of: receiving, from the mmWave terminal, a first fallback request message for requesting fast fallback; operating a fallback timer for determining whether or not to perform fallback after receiving the first fallback request message; and determining whether or not a second fallback request message for requesting fast fallback has been received from a mmWave base station within the fallback timer.