RLC Error Control Message Generation Timing
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Solution Overview
Problem
In wireless communication systems like LTE, the dynamic scheduling of uplink resources can cause delays in transmitting error control messages, leading to outdated status reports and unnecessary retransmissions due to the lack of immediate access to transmission resources, resulting in inefficient use of system resources and potential errors in receiver state information.
Innovation Solution
The method involves signaling the MAC layer for link resources needed to transmit error control messages and generating these messages only after receiving an indication that resources are scheduled, thereby avoiding queuing and transmission of stale messages, and using a modified interface between the RLC and MAC layers to defer message generation until resources are available, ensuring that error control messages include updated information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If error control messages are generated immediately upon receiving triggers (polls, missing PDU detection), then the status information is current and accurate, but transmission delays occur due to scheduled resource allocation in LTE uplink
Solution Approach 1:
The patent applies preliminary action by having the RLC layer pre-generate error control messages (status reports) when triggers occur, and pre-indicate to the MAC layer that link resources are needed. This allows the message content to be prepared in advance with current status information, while the actual transmission is deferred until MAC layer resource allocation is granted, thus resolving the conflict between information accuracy and transmission timing
2Reliability
If error control messages are generated immediately, then the status information is current, but outdated messages may be queued and transmitted if resources are not immediately available
Solution Approach 1:
The patent implements dynamics by making the error control message generation conditional on MAC layer resource availability. Instead of a fixed immediate generation approach, the system dynamically adjusts message generation timing based on real-time resource grant status. The RLC layer generates messages only after receiving indication from MAC that resources are scheduled, ensuring messages are created with current status information rather than queuing outdated information for later transmission
3Measurement precision
If status reports are sent frequently in response to multiple triggers, then the status information is up-to-date, but unnecessary retransmissions occur due to status-prohibit timer constraints
Solution Approach 1:
The patent applies feedback by implementing a signaling mechanism between RLC and MAC layers where the RLC layer indicates to MAC when link resources are needed for error control message transmission. This feedback loop allows the system to coordinate message generation with actual resource availability and status-prohibit timer status, enabling timely transmission of accurate status reports while avoiding unnecessary retransmissions by respecting timer constraints through MAC layer control
Data Source
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AI summary
Methods and apparatus for processing error control messages, such as RLC ARQ control messages, are disclosed. An exemplary method comprises signaling a medium access controller (MAC) that link resources are needed for transmitting data, receiving an indication from the MAC that link resources for transmitting the data are scheduled, and generating an error control message after receiving said indication, based on a current error control status. The error control message is then forwarded to the MAC for transmission. Because the generation of an error control message is delayed until resources for its transmission are scheduled, the queuing of stale control messages is avoided.