Cognitive Node Synchronization via Physical Random Access Channel Guard Time
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Solution Overview
Problem
In heterogeneous networks, existing technologies face challenges in efficiently distributing synchronization information and beacon signals within local domains without interfering with other network users, especially for autonomous femto base stations that need to operate with minimal network assistance and avoid interference.
Innovation Solution
A method and apparatus that utilize an interference-free guard time period of a cellular user terminal's transmission in the physical random access channel to distribute synchronization and beacon signals locally, compensating for the maximum round trip delay in the cell, allowing cognitive femto cells to adapt and operate autonomously while minimizing network involvement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If autonomous femto base stations distribute synchronization information using dedicated channels, then synchronization reliability is improved, but network resource consumption and complexity increase
Solution Approach 1:
The patent makes the uplink physical random access channel serve dual purposes: maintaining cellular uplink synchronization and distributing synchronization information for autonomous femto base stations. This multi-functionality eliminates the need for dedicated synchronization channels, reducing network resource consumption while maintaining synchronization reliability.
Solution Approach 2:
Autonomous femto base stations independently extract and utilize synchronization information from overheard cellular uplink signals without requiring network assistance or dedicated synchronization resources. This self-service approach reduces network involvement and resource consumption while enabling autonomous operation.
2Extent of automation
If femto base stations operate autonomously without network assistance, then network involvement is reduced, but interference management becomes more difficult
Solution Approach 1:
The cellular uplink signal serves as an intermediary that carries synchronization information usable by both cellular users and autonomous femto base stations. By deriving synchronization from this common reference, the patent enables autonomous operation while maintaining coordination with the cellular network, thereby managing interference effectively.
Solution Approach 2:
The patent utilizes the guard time period parameter of the physical random access channel, which is specifically designed to accommodate round trip delay variations. By distributing synchronization information during this interference-free guard period, the system enables autonomous femto base station operation while preventing uplink interference, as the synchronization signals are transmitted when no cellular uplink transmissions occur.
3Measurement precision
If synchronization information is distributed frequently, then synchronization accuracy is improved, but energy consumption increases
Solution Approach 1:
The patent distributes synchronization information periodically during each physical random access channel's guard time period. This periodic distribution maintains synchronization accuracy by providing regular updates while consuming minimal energy, as the transmission occurs only during brief, predetermined intervals rather than continuously.
Data Source
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AI summary
An apparatus comprising at least one processor and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to at least evaluate, in a cognitive node, transmission of a physical random access channel in an uplink of a communications carrier, and, based on the evaluating, utilize an interference-free guard time period of a cellular user terminal's transmission in the physical random access channel, for distributing a synchronization signal and a beacon signal locally, the cellular user terminal's transmission in the physical random access channel including a guard time period that compensates a maximum round trip delay in a cell.