DMRS Sequence Correlation for PDCCH Decoding Complexity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In current Long Term Evolution (LTE) systems, physical downlink control channel (PDCCH) decoding at mobile devices consumes significant power due to frequent blind decoding attempts, as devices must periodically monitor for downlink control messages without prior knowledge of their presence, leading to unnecessary power consumption.
Innovation Solution
The implementation of specially designed and allocated demodulation reference signal (DMRS) sequences, which are orthogonal or quasi-orthogonal across users and PDCCH aggregation levels, allows mobile devices to determine the presence of intended PDCCHs by calculating correlation-based quality metrics, thereby reducing unnecessary decoding attempts and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mobile devices perform frequent PDCCH blind decoding attempts to monitor for downlink control messages, then the reliability of control channel reception is improved, but power consumption increases significantly
Solution Approach 1:
The patent applies preliminary action by performing DMRS detection before PDCCH blind decoding. The mobile device first detects the presence of PDCCH by correlating received DMRS sequences with locally generated reference sequences. Only when a PDCCH is detected does the device proceed to blind decoding, thus avoiding unnecessary power consumption from decoding attempts when no control message is present.
Solution Approach 2:
The patent introduces DMRS detection as an intermediary step between signal reception and PDCCH blind decoding. This intermediary mechanism uses orthogonal DMRS sequences to indicate PDCCH presence, allowing the mobile device to filter out subframes without intended PDCCHs before committing to energy-intensive blind decoding operations.
2Reliability
If mobile devices perform PDCCH blind decoding without prior knowledge of PDCCH presence, then all possible control messages can be detected, but decoding complexity increases
Solution Approach 1:
The patent reduces decoding complexity by performing preliminary PDCCH detection using DMRS sequences before initiating blind decoding. The mobile device correlates received DMRS with local references to determine PDCCH presence and aggregation level, thereby eliminating the need to perform blind decoding across all possible candidates and significantly reducing computational complexity.
Solution Approach 2:
DMRS detection serves as an intermediary that provides prior knowledge about PDCCH presence and aggregation level. This intermediary step enables the mobile device to narrow down the search space for blind decoding, transforming a high-complexity exhaustive search into a targeted decoding process with known parameters.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces PDCCH decoding complexity and power consumption by enabling mobile devices to efficiently identify intended PDCCHs, avoiding blind decoding processes and switching to power-saving modes earlier, thus optimizing battery life.
Implementation Method 1
calculating a correlation-based quality metric indicating a correlation between the received candidate DMRS sequence and a local DMRS sequence
Data Source
AI summary
Aspects of the disclosure provide a method for reducing physical downlink control channel (PDCCH) decoding complexity at a user equipment (UE) in a wireless communication network. The method can include receiving from a base station a candidate demodulation reference signal (DMRS) sequence that is carried in a subframe and associated with a PDCCH carried in the subframe, calculating a correlation-based quality metric indicating a correlation between the received candidate DMRS sequence and a local DMRS sequence, and performing a PDCCH decoding process to decode the PDCCH when the quality metric is greater than a threshold.