RACH Availability Checks for Alternative RAT Discovery Delays
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Solution Overview
Problem
User equipment (UE) camped on a cell within a radio access network of a first radio access technology (RAT) faces significant delays in discovering the availability of another RAT or radio resource due to conventional methods requiring substantial messaging and state transitions, which are inefficient and time-consuming.
Innovation Solution
A UE initiates a random access channel (RACH) procedure using dedicated RACH resources to quickly determine the availability of an alternative RAT and/or radio resource by sending a Msg1 or MsgA, with the serving base station responding with Msg2 or MsgB indicating availability, employing methods like antenna array processing to estimate UE location and consider load factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional messaging and state transition methods are used to discover alternative RAT availability, then the UE can obtain availability information, but the process results in significant delays and inefficiency
Solution Approach 1:
The patent extracts the availability inquiry function from the conventional complex messaging and state transition procedures, embedding it directly into the RACH procedure. By adding an availability indicator field to existing RACH messages (Msg1/MsgA and Msg2/MsgB), the system obtains availability information without requiring separate messaging sequences or UE state changes, thereby eliminating significant delays.
Solution Approach 2:
The RACH procedure, traditionally used for random access and connection establishment, is enhanced to serve multiple functions simultaneously. By incorporating availability inquiry and response capabilities into the existing RACH message structure, the same procedure now performs both connection management and availability discovery, eliminating the need for separate dedicated procedures and reducing overall signaling overhead.
2Loss of information
If the UE transitions out of idle/inactive state to check availability, then availability information can be obtained, but the state transition causes additional delays
Solution Approach 1:
The patent extracts the availability check function from the state transition process. Instead of requiring the UE to transition from idle/inactive to connected state merely to obtain availability information, the inquiry is embedded within the RACH procedure that can be initiated while remaining in the current state. The availability indicator is included in the random access response, allowing information acquisition without unnecessary state changes.
3Speed
If dedicated RACH resources are allocated for availability checks, then the availability determination speed improves, but the device and system complexity increases
Solution Approach 1:
The patent reuses existing RACH resources and message structures for the dual purpose of random access and availability inquiry. By incorporating availability indicator fields into standard RACH messages (Msg1/MsgA and Msg2/MsgB) and using existing RACH occasion and preamble resources, the system achieves fast availability determination without requiring separate dedicated physical channels or resource structures, thereby limiting the increase in complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables rapid determination of alternative RAT and/or radio resource availability, reducing delays and facilitating faster connections or dual connectivity, while maintaining the UE in an idle or inactive state without attempting channel access.
Implementation Method 1
employing methods like antenna array processing to estimate UE location
Data Source
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AI summary
A method in a base station configured to communicate with a user device using a first RAT and/or a first radio resource includes receiving (422 or 521) a first random access message from the user device via first RACH resources, determining (426 or 526) that the first random access message is requesting RAT and/or radio resource availability, and transmitting (430 or 529) to the user device a second random access message indicating whether a second RAT and/or a second radio resource is available to the user device.