RAR Last-Message Indicator Reduces Access Channel Delay
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communication systems, user equipment (UE) experiences delays due to the need to monitor the entire RAR window for acknowledgment of its preamble transmission, even if it is not received by the eNB, leading to unnecessary retransmissions and increased access channel delay.
Innovation Solution
Incorporating a 'Last-message-in-window' indicator in the RAR message to notify the UE if it is the last transmission within the RAR window, allowing it to retransmit the access request earlier if not acknowledged, thereby reducing waiting time and delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE monitors the entire RAR window for acknowledgment, then the reliability of access channel is improved, but the access channel delay increases
Solution Approach 1:
The eNB sends a preliminary indication message before the RAR window expires to inform UEs that their preamble was not detected. This allows UEs to stop monitoring early and retransmit promptly, resolving the contradiction by providing advance information that prevents unnecessary waiting time while maintaining reliable access through continued monitoring until the indication is received.
2Reliability
If the RAR window is extended to accommodate all preamble responses, then the completeness of acknowledgment is improved, but the waiting time for UE increases
Solution Approach 1:
The RAR window is segmented into two parts: UEs receive either an early indication message (if preamble not detected) or a normal RAR message (if preamble detected). This segmentation allows the system to maintain complete acknowledgment coverage while reducing waiting time for UEs whose preambles were not detected, as they can stop monitoring early upon receiving the indication message.
3Productivity
If the UE retransmits preamble immediately upon failure, then the access channel productivity is improved, but the protocol complexity increases
Solution Approach 1:
The eNB provides feedback through the indication message to inform UEs whether their preamble was detected. This feedback mechanism enables UEs to make informed decisions about retransmission timing without requiring complex protocol logic, as the eNB's indication message clearly signals whether the UE should stop monitoring and retransmit, thus improving productivity while keeping protocol complexity manageable.
Data Source
AI summary
A system and method for reducing access channel delay in a wireless communication system includes a step 601 of sending an initial access request response that includes identifiers of any initial access requests, including an indicator that indicates whether any more responses with identifiers are going to be sent within a predefined time period. A next step 602 includes receiving the response. A next step 604 includes recognizing that a particular identifier from the initial access request is not in the response. A next step 606 includes determining from the indicator that there will be no more responses with identifiers sent within the predefined time period. A next step 608 includes transmitting another initial access request before the end of the predefined time period.