PDCCH Demapping Using Stale Channel Estimates for Faster Microsleep
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Solution Overview
Problem
In wireless communication systems, particularly in 5G NR, decoding the control channel represents a bottleneck for triggering microsleeps due to the need for channel estimation and noise estimation, limiting power savings as power-consuming components cannot be turned off until decoding is complete.
Innovation Solution
Removing channel estimation and noise estimation from the demapping path, allowing the UE to perform PDCCH demapping immediately using stale channel and noise estimates from a previous subframe, enabling microsleeps to be triggered sooner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If channel estimation and noise estimation are performed before PDCCH demapping to ensure accurate decoding, then decoding reliability is improved, but PDCCH decode time increases and power savings are limited
Solution Approach 1:
The patent performs channel estimation and noise estimation in advance (in previous subframes) before they are actually needed for PDCCH demapping. The channel estimate from subframe n-2 and noise estimate from subframe n-1 are stored and reused when needed, eliminating the need to perform these estimations immediately before demapping and enabling earlier microsleep triggering.
Solution Approach 2:
The patent creates copies of channel estimates and noise estimates from previous subframes and reuses them for current PDCCH demapping operations. Instead of performing fresh estimations, the system copies stale estimates from memory and applies them to current data, significantly reducing processing time while maintaining acceptable decoding reliability.
2Measurement precision
If channel estimation and noise estimation are performed serially before demapping to ensure accurate decoding, then decoding accuracy is improved, but processing speed decreases and power consumption increases
Solution Approach 1:
Channel estimation and noise estimation are performed in advance in previous subframes (n-2 and n-1 respectively) and stored for later use. This preliminary action allows the current PDCCH demapping to use pre-computed estimates without waiting for serial estimation processes, thereby improving processing speed while maintaining decoding accuracy through the use of recent stale estimates.
Solution Approach 2:
The system copies channel and noise estimates from previous subframes and reuses them for current PDCCH decoding. This copying approach maintains measurement precision by using recently captured estimates while dramatically improving productivity by eliminating the need for serial estimation processes before each demapping operation.
3Measurement precision
If channel estimation and noise estimation are performed in the current subframe to ensure fresh estimates, then estimation accuracy is improved, but power-consuming components must remain active longer reducing power savings
Solution Approach 1:
Channel and noise estimates are computed in advance in previous subframes and stored for reuse. This preliminary computation allows the UE to skip performing these estimations in the current subframe, enabling power-consuming components to enter low power state earlier and achieve greater power savings while maintaining acceptable estimation accuracy through the use of stale but sufficient estimates.
Solution Approach 2:
The system copies channel and noise estimates from previous subframes instead of computing fresh estimates in the current subframe. This copying approach maintains measurement precision by using recent estimates while significantly reducing power consumption by avoiding the execution of estimation algorithms in the current active subframe.
4Reliability
If the UE waits to decode PDCCH completely before triggering microsleep to ensure reliable grant detection, then downlink grant detection reliability is improved, but the time components remain active increases reducing power efficiency
Solution Approach 1:
Channel and noise estimates are prepared in advance in previous subframes, enabling the PDCCH demapping and decoding process to start earlier in the current subframe. This preliminary preparation allows the UE to complete decoding faster and trigger microsleep earlier, reducing the duration of active state while maintaining reliable downlink grant detection through the use of pre-computed estimates.
Data Source
AI summary
To reduce power consumption, a user equipment (UE) may trigger a microsleep in a subframe when a physical downlink control channel (PDCCH) does not include a downlink grant. However, because the microsleep depends on the PDCCH not including a downlink grant, the UE cannot trigger the microsleep until after the PDCCH is decoded. Accordingly, in some aspects, a UE may enable an aggressive extra microsleep in which a microsleep duration may be increased by reducing a PDCCH decode time. For example, a UE may use a stale channel estimate and noise estimate from a previous subframe to perform PDCCH demapping when conditions related to a PDCCH block error rate are satisfied. In this way, removing channel estimation and noise estimation from a PDCCH demapping path may reduce the PDCCH decode time, whereby the UE may trigger a microsleep sooner to increase a sleep ratio and thereby increase power savings.