Multi-APG Initial Access for Cell-Free Wireless Coverage
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Solution Overview
Problem
The initial access procedure in traditional cellular wireless communication systems is limited by point-to-point communication, leading to coverage constraints and inefficient resource utilization, particularly in cell-free systems where multiple access points serve a UE.
Innovation Solution
A method for initial access in wireless networks involving multiple access point groups (APGs) where UEs measure signal power from each APG, obtain RA configuration, and transmit preambles to multiple APGs meeting a predetermined criterion, allowing the network to select the best APGs for connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional point-to-point initial access procedure is used, then the procedure is simple to implement, but coverage is limited and resource utilization is inefficient
Solution Approach 1:
The system segments the network into multiple Access Point Groups (APGs) instead of relying on a single access point. Each APG can independently handle initial access, allowing the UE to select from multiple groups based on signal quality measurements, thereby expanding coverage without significantly increasing procedural complexity
Solution Approach 2:
The network performs preliminary actions by having multiple APGs transmit reference signals and broadcast RA configurations before the UE needs to access the network. The UE measures signal power from these pre-transmitted signals and selects the best APG, enabling faster and more reliable initial access across extended coverage areas
2Productivity
If a UE connects to a single TRP for initial access, then the connection establishment is straightforward, but resource utilization is inefficient and latency is increased
Solution Approach 1:
Multiple APGs are merged into the initial access procedure, allowing the UE to simultaneously consider and potentially connect to multiple access point groups. This combining of multiple access points improves resource utilization by distributing traffic and reducing latency, while the UE still follows a relatively simple measurement and selection process
Solution Approach 2:
The system performs excessive action by having more APGs transmit reference signals and available RA configurations than the UE will ultimately use. The UE measures all available APGs but only selects the best one(s) based on signal power criteria, allowing the network to prepare multiple options in advance without requiring the UE to process all of them equally
3Reliability
If multiple APGs transmit reference signals on the same radio resources, then resource utilization is maximized, but signal measurement and selection becomes difficult
Solution Approach 1:
Each APG is assigned distinct radio resources (time, frequency, or spatial) for transmitting reference signals during initial access. This local differentiation allows the UE to accurately measure and identify signals from individual APGs without interference, ensuring reliable signal quality assessment while maintaining efficient overall resource utilization across the network
Data Source
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AI summary
Method carried out in a user equipment, UE, for initial access to a wireless network comprising a plurality of access point groups, APGs, the method comprising: measuring (520) received signal power of reference signals from said APGs, wherein each APG transmits said reference signals using different radio resources; obtaining (530) random access, RA, configuration associated with one or more of said APGs; initiating RA preamble transmission (540), based on said RA configuration, to each of the APGs which meet a predetermined criterion based on the measured received signal power.