RACH Timeline Switching for RedCap UE SSB Monitoring
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Solution Overview
Problem
RedCap UEs, due to their low bandwidth capability, struggle to measure and track synchronization signal blocks (SSBs) during a random access channel (RACH) procedure, leading to potential congestion and decreased likelihood of successful RACH completion due to restricted access to essential network information.
Innovation Solution
Implementing an extended timeline that allows RedCap UEs to switch from a RedCap BWP to a non-RedCap BWP during the RACH procedure to monitor for SSBs, enabling detection of different SSBs and increasing the chances of successful RACH completion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If RedCap UEs operate in RedCap BWP during RACH procedure, then device complexity is reduced, but ability to detect and measure SSBs deteriorates
Solution Approach 1:
The patent segments the BWP operation into two distinct modes: RedCap BWP for normal RACH procedure and non-RedCap BWP for SSB detection. The UE can switch between these segmented modes based on procedural needs, maintaining low complexity during normal operation while enabling enhanced detection capability when required.
Solution Approach 2:
The patent introduces dynamic BWP switching capability that allows the UE to transition from static RedCap BWP operation to temporary non-RedCap BWP operation. This dynamic adjustment enables the system to adapt the UE's operational characteristics in real-time based on whether SSB detection is required, resolving the contradiction between fixed low-complexity operation and variable detection capability.
2Ease of operation
If RedCap UEs are restricted to RedCap BWP, then ease of operation is improved, but RACH procedure success rate deteriorates
Solution Approach 1:
The patent implements preliminary action by having the UE detect SSBs in non-RedCap BWP before initiating or during the RACH procedure in RedCap BWP. This advance detection and preparation of synchronization information ensures that when the UE needs to perform RACH, it has access to necessary network timing and frequency references, thereby improving success rate without complicating the actual RACH operation.
Solution Approach 2:
The patent introduces non-RedCap BWP as an intermediary environment that provides SSB detection capabilities. The UE uses this intermediary BWP temporarily to acquire synchronization signals, then returns to the simpler RedCap BWP for RACH transmission. This intermediary approach allows the UE to benefit from enhanced detection capabilities without permanently operating in a more complex mode.
3Difficulty of detecting and measuring
If RedCap UEs switch to non-RedCap BWP to monitor SSBs, then SSB detection capability is improved, but device complexity increases
Solution Approach 1:
The patent implements dynamic BWP switching that allows the UE to temporarily adjust its operational bandwidth capability. Rather than permanently increasing device complexity, the UE dynamically switches to non-RedCap BWP only when SSB detection is required, then returns to RedCap BWP for normal operation. This dynamic approach enables enhanced detection capability on-demand without permanently increasing device complexity.
Data Source
AI summary
Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for performing a random access channel (RACH) procedure. According to one aspect, a method for wireless communication by a user equipment (UE), generally includes detecting at least a first synchronization signal block (SSB) transmitted in a first bandwidth part (BWP), transmitting, in a second BWP associated with the first SSB, a number of first messages as part of a random access channel (RACH) procedure, monitoring, in the second BWP, for a second message sent in response to the number of first messages, and switching back to the first BWP to monitor for SSBs, if the second message is not received within a first timeline after transmitting the number of first messages and one or more conditions are met.