HARQ Failure Indication for UMTS OLPC Performance
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Solution Overview
Problem
In the context of UMTS wireless communication, the serving Node B lacks sufficient information to determine whether the termination of a HARQ process is due to a MAC-e reset requested by the SRNC or another reason, such as NACK-ACK Error, leading to degraded outer loop power control (OLPC) performance, especially with 10 ms transmission time intervals.
Innovation Solution
The SRNC informs the Node B of an impending MAC-e reset for the UE, and the Node B sends a HARQ Failure Indication with the number of retransmissions for each HARQ process not decoded by the time of the reset, ensuring accurate OLPC calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the Node B does not send HARQ Failure Indication when MAC-e reset occurs, then the system complexity is reduced, but the OLPC performance degrades due to insufficient information
Solution Approach 1:
The SRNC sends a Reset Indicator to the Node B in advance before the MAC-e reset occurs. This preliminary action allows the Node B to prepare for the upcoming reset event and send the HARQ Failure Indication at the appropriate time, ensuring that OLPC performance is not degraded while avoiding the need for complex continuous monitoring mechanisms.
2Reliability
If the Node B sends HARQ Failure Indication for all termination cases, then the OLPC performance is improved, but the loss of information increases due to inability to distinguish MAC-e reset from other causes
Solution Approach 1:
The SRNC provides feedback to the Node B by sending a Reset Indicator that specifies whether an impending MAC-e reset will occur. This feedback mechanism enables the Node B to distinguish between MAC-e reset terminations and other termination causes, allowing selective sending of HARQ Failure Indication only when appropriate, thus preserving information accuracy while improving OLPC performance.
3Measurement precision
If the Node B monitors all HARQ process terminations, then the measurement precision is improved, but the use of energy increases due to continuous monitoring requirements
Solution Approach 1:
The SRNC notifies the Node B in advance about impending MAC-e reset events through the Reset Indicator. This allows the Node B to focus its monitoring efforts specifically on HARQ processes that will be affected by the reset, rather than continuously monitoring all HARQ processes, thereby reducing energy consumption while maintaining measurement precision for relevant termination cases.
Data Source
AI summary
A method by which a Node B is informed by a serving radio network controller that a medium access control-e reset is to be performed by a user equipment in communication with the Node B, so that the Node B can then provide failure indications of all hybrid automatic repeat request processes that are not decoded by the time of the medium access control-e reset. Corresponding equipment and software are also provided.