Relay Node Subframe Management for Un Interface Recovery
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Solution Overview
Problem
In LTE-A systems, when a problem occurs in the Un interface between a donor eNB and a relay node (RN), the RN releases its subframe to prevent interference and recover the connection, but there is a need to optimize the time required for solving the Un interface issues without causing signaling overhead and delay in re-establishing the RRC connection.
Innovation Solution
A method is implemented where a timer is started when a connection problem with the network node is detected, and the RN uses its specific subframe for recovery up to a certain point, transitioning to an RRC idle state and performing cell selection if the timer expires, allowing for optimized Un interface recovery while maintaining the Uu interface during the timer's running period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the RN releases the RN subframe when a problem occurs in the Un interface, then interference is prevented and connection recovery is enabled, but the time required for solving the Un interface problem increases
Solution Approach 1:
The RN performs preliminary actions by maintaining the Uu interface during the timer running period, allowing it to prepare for potential connection re-establishment while still attempting Un interface recovery. This preliminary preparation reduces the overall recovery time by having resources ready in advance.
Solution Approach 2:
The system dynamically adjusts the RN's operational state based on the timer status. While the timer is running, the RN maintains both Uu and Un interfaces; when the timer expires, it transitions to releasing the Uu interface and performing cell selection. This dynamic behavior optimizes recovery time by adapting to the actual connection status.
2Loss of time
If the RN maintains the Uu interface during Un interface recovery, then the recovery time is optimized, but interference may occur
Solution Approach 1:
The timer acts as an intermediary mechanism that mediates between maintaining the Uu interface and preventing interference. It provides a controlled time window during which the Uu interface is maintained for recovery purposes, after which it is released to prevent harmful interference, thus balancing both requirements.
Solution Approach 2:
The system changes the operational parameter of the Uu interface based on the timer status. During the timer running period, the Uu interface is active; upon timer expiration, the interface is released. This parameter change allows the system to optimize recovery time while preventing interference through clear state transitions.
3Reliability
If the RN transitions to RRC idle state and performs cell selection when the timer expires, then the RRC connection is re-established, but signaling overhead and delay occur
Solution Approach 1:
The RN performs preliminary cell selection and maintains Uu interface connectivity during the timer running period, so that when the timer expires, the transition to RRC idle state and cell selection can be executed more efficiently with reduced signaling overhead, as preliminary preparations have already been made.
Data Source
AI summary
A method is described for operating a device in a wireless communication system. The device communicates with a base station using a subframe for the device only; detects, by the device, a problem with a connection between the device and the base station. The device starts a timer upon detecting the problem with the connection between the device and the base station. The device releases a restriction of using the subframe for the device only, if the timer expires. The problem with the connection between the device and the base station is associated with a radio link failure. The detection of a problem with the connection between the device and the base station comprises detecting consecutive out-of-sync indications.