RRC Connection Release Delay for Coverage Enhancement
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Solution Overview
Problem
User equipment (UE) may not have sufficient time to transmit an acknowledgement of a RRCConnectionRelease message to a base station (BS), leading to inefficient communication as the BS is unsure if the message was received, particularly when the UE is in CE mode.
Innovation Solution
The base station configures RRC connections with communication devices and transmits RRCConnectionRelease messages, determining the duration for the UE to leave connected mode based on CE mode status, allowing sufficient time for acknowledgement, thereby preventing unnecessary retransmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the base station uses a fixed short duration to determine UE leaves connected mode, then the base station can quickly release resources, but the UE in CE mode does not have sufficient time to transmit acknowledgement
Solution Approach 1:
The base station dynamically adjusts the duration for determining that the UE has left connected mode based on the UE's operational mode. When the UE is in CE mode, the base station uses a first (longer) duration; when not in CE mode, it uses a second (shorter) duration. This dynamic adjustment ensures that UEs in CE mode have sufficient time to transmit acknowledgements while allowing faster resource release for other UEs.
Solution Approach 2:
The base station changes the time parameter for determining connection release based on the UE's CE mode status. By adjusting this parameter (duration) according to different operational conditions, the system ensures reliable acknowledgement transmission for CE mode UEs while maintaining efficient resource management for non-CE mode UEs.
2Reliability
If the base station waits for acknowledgement from UE in CE mode, then communication reliability improves, but communication efficiency decreases due to longer waiting time
Solution Approach 1:
The base station applies different waiting durations specifically for UEs in CE mode versus other UEs. This localized quality adjustment ensures that only CE mode UEs receive the extended waiting time needed for reliable acknowledgement transmission, while other UEs benefit from faster resource release without unnecessary delays.
Solution Approach 2:
The system dynamically adapts the acknowledgement waiting time based on the UE's operational mode. This dynamic approach ensures that the base station waits appropriately long for CE mode UEs to maintain reliability, while avoiding unnecessary waiting time for non-CE mode UEs, thus optimizing both reliability and efficiency.
3Reliability
If the base station retransmits RRCConnectionRelease message due to timeout, then message delivery reliability improves, but communication efficiency worsens due to unnecessary retransmissions
Solution Approach 1:
The base station preliminarily determines an appropriate duration for expecting acknowledgement based on the UE's CE mode status before the acknowledgement timeout occurs. By setting this duration in advance (longer for CE mode, shorter for others), the base station prevents unnecessary retransmissions while ensuring reliable message delivery, thus improving communication efficiency.
Solution Approach 2:
The system uses feedback from the UE's operational mode status to adjust the base station's waiting behavior. By monitoring whether the UE is in CE mode and adjusting the acknowledgement expectation duration accordingly, the system avoids unnecessary retransmissions for non-CE mode UEs while ensuring reliable delivery for CE mode UEs.
Data Source
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AI summary
A communication device of handling communication with a base station (BS) comprises instructions of being configured a radio resource control (RRC) connection with the BS by the BS; receiving an RRCConnectionRelease message via the RRC connection from the BS; and delaying at least one operation for a first duration, when receiving the RRCConnectionRelease message, wherein the first duration is from a first time instant at which the RRCConnectionRelease message is received, and the first duration is a first value or a smaller one of the first value and a second value, wherein the first value is predefined as more than 60 ms and the second value is from the first time instant to a second time instant at which the communication device successfully acknowledges a reception of the RRCConnectionRelease message to the BS.