Base Station Random Access for Link Budget Constrained Devices
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Solution Overview
Problem
Link budget limited wireless devices face challenges in performing random access procedures due to their limited reception and transmission capabilities, which can result in unsuccessful message exchanges with base stations, especially at the cell edge or with hardware constraints.
Innovation Solution
A base station detects physical preamble messages from link budget limited devices using a lower correlation threshold and adjusts message characteristics, such as increasing control channel aggregation, boosting power, and using low modulation and coding schemes, to improve message reception and transmission success, and may instruct devices to use transmission time interval bundling or explicitly indicate link budget constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a base station uses a standard correlation threshold for detecting physical preamble messages, then detection accuracy for non-constrained devices is maintained, but link budget limited devices fail to successfully complete random access procedures
Solution Approach 1:
The patent applies different correlation thresholds based on device characteristics. Specifically, a first (lower) correlation threshold is used for link budget limited devices and a second (higher) correlation threshold for non-constrained devices. This local differentiation allows the system to optimize detection sensitivity for vulnerable devices while maintaining standard accuracy for others, resolving the contradiction between reliability for constrained devices and measurement precision overall.
2Reliability
If a base station uses standard message transmission parameters, then network resource efficiency is maintained, but link budget limited devices cannot successfully receive messages
Solution Approach 1:
The patent dynamically adjusts message transmission parameters based on device link budget constraints. For link budget limited devices, the base station modifies aggregation level, modulation and coding scheme (MCS), and power settings. These parameter changes ensure successful message reception by constrained devices while the system maintains standard parameters for other devices, thus managing energy consumption efficiently.
3Reliability
If link budget limited devices use standard transmission characteristics, then device complexity is minimized, but message transmission fails due to insufficient signal quality
Solution Approach 1:
The patent implements preliminary identification of link budget limited devices during the random access procedure. The base station detects device constraints early (e.g., through preamble detection or device indication) and pre-configures appropriate transmission parameters before actual data transmission. This preliminary action allows constrained devices to use optimized transmission characteristics without increasing their operational complexity, as the configuration is managed by the network side.
Data Source
AI summary
This disclosure relates to accommodating link budget constrained wireless devices performing random access procedures. A base station may detect a preamble message from a wireless device. It may be determined that the preamble message is received from a link budget constrained wireless device. Characteristics of a response message may be selected based at least in part on determining that the preamble message is received from a link budget constrained wireless device. The response message may be transmitted to the link budget constrained wireless device using the selected characteristics.