Network Listening Synchronization Signal Generation for Small Cells
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing small cell synchronization technologies, such as IEEE 1588 and GPS or Network Listening (NL) schemes, face challenges in providing accurate timing and frequency synchronization, especially in indoor environments where GPS signals are unreliable and NL synchronization precision degrades with distance from macro cells.
Innovation Solution
A method and apparatus for generating and transmitting a Network Listening (NL) synchronization signal using resource blocks offset by a predetermined frequency or time from existing 3GPP specifications, enabling small cells to receive accurate timing and frequency synchronization through a Long Term Evolution (LTE) or Wideband Code Division Multiple Access (WCDMA) network, even in indoor settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GPS synchronization scheme is used, then timing synchronization and frequency synchronization can be acquired, but it cannot be used in indoor environments where GPS signals are blocked
Solution Approach 1:
The patent introduces a macro cell as an intermediary synchronization source. Instead of directly using GPS or having small cells synchronize independently, the macro cell receives GPS synchronization signals and relays them to small cells through downlink signals. This intermediary approach allows indoor small cells to acquire synchronization indirectly through the macro cell's coverage area.
Solution Approach 2:
The patent replaces the direct GPS reception mechanism with a network-based synchronization mechanism. Rather than each small cell having its own GPS receiver (mechanical/electronic system), the synchronization function is substituted by receiving processed synchronization signals from the macro cell through the existing wireless communication infrastructure.
2Adaptability or versatility
If Network Listening (NL) synchronization is used, then small cells can receive synchronization signals from macro cells, but timing synchronization precision degrades as distance between macro cell and small cell increases
Solution Approach 1:
The patent applies preliminary timing adjustment at the macro cell side. The macro cell pre-calculates and applies timing offsets based on the distance to each small cell before transmitting synchronization signals. This preliminary action compensates for the expected propagation delay, ensuring that small cells receive synchronized signals even at greater distances.
Solution Approach 2:
The patent changes the timing parameters of synchronization signals dynamically. Different timing offsets are applied to synchronization signals transmitted to different small cells based on their distances from the macro cell. This parameter adjustment maintains synchronization precision across varying deployment scenarios.
3Reliability
If conventional NL synchronization resources are used, then small cells can synchronize with macro cells, but synchronization signals interfere with user data transmission in TDD systems
Solution Approach 1:
The patent segments the time-frequency resources into distinct synchronization resources and user data resources. By allocating separate resource blocks and time slots for synchronization signals versus user data transmission, the patent eliminates interference between these two functions while maintaining both synchronization reliability and data transmission quality.
Data Source
AI summary
A method of providing a synchronization signal to at least one small cell includes receiving a synchronization reference signal; extracting a synchronization signal from the synchronization reference signal; generating a network listening (NL) synchronization signal based on the synchronization signal; and transmitting the NL synchronization signal for reception by the at least one small cell.