Synchronization Beacon for Phase Sync in LTE-Advanced Small Cells
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Solution Overview
Problem
Existing solutions for providing phase synchronization to non-phase synchronized cellular base stations, especially in LTE-Advanced networks, are inadequate in low coverage conditions and require significant network upgrades or rely on GPS, which is not feasible indoors, and may not be backwards-compatible with legacy systems.
Innovation Solution
A method involving a new physical signal, the Synchronization Beacon, using orthogonal Walsh-Hadamard sequences broadcast by phase-synchronized base stations to non-phase synchronized base stations, which does not require backhaul upgrades and can be detected by small cells even in interference-limited scenarios, utilizing unused resource elements and BPSK modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GPS or traditional synchronization techniques are used, then phase synchronization can be achieved, but network upgrades are required and GPS is not feasible indoors
Solution Approach 1:
The patent introduces a synchronization beacon as an intermediary signal that carries phase synchronization information from macro cells to small cells. This beacon acts as a mediator that enables synchronization without requiring complex network infrastructure upgrades or GPS equipment, solving the contradiction between achieving reliable synchronization and avoiding device complexity.
Solution Approach 2:
The system enables small cells to achieve phase synchronization autonomously by detecting and processing synchronization beacons transmitted over existing air interfaces. Small cells self-configure their synchronization parameters without requiring manual network upgrades or external GPS assistance, allowing indoor deployment while maintaining synchronization reliability.
2Reliability
If synchronization protocols are implemented over backhaul links, then time and phase synchronization can be achieved, but significant network upgrades are required
Solution Approach 1:
The patent replaces the mechanical/physical infrastructure approach (backhaul link upgrades, synchronization protocols requiring dedicated hardware) with an electromagnetic signal approach (synchronization beacons transmitted over existing air interfaces). This substitution eliminates the need for significant network upgrades while maintaining reliable time and phase synchronization.
3Reliability
If existing synchronization methods are used, then synchronization can be achieved in good coverage conditions, but detection fails in low coverage and interference-limited scenarios
Solution Approach 1:
The synchronization beacon is designed with specific local qualities optimized for detection in challenging conditions: it uses dedicated resource elements with specific sequence structures (length-8 orthogonal sequences) that provide robust correlation properties. These localized optimizations at the signal level enable reliable detection even in low coverage and interference-limited scenarios where traditional synchronization methods fail.
4Reliability
If new physical signals are introduced for synchronization, then small cells can acquire phase synchronization in low coverage conditions, but compatibility with legacy terminals must be maintained
Solution Approach 1:
The patent segments the LTE signal structure by allocating specific resource elements (REs) dedicated to synchronization beacons, separate from those used by legacy terminals. This segmentation allows the new synchronization functionality to coexist with legacy systems: small cells can detect the beacon sequences on designated REs while legacy terminals continue to operate using existing synchronization signals, maintaining backwards compatibility while enabling phase synchronization acquisition in low coverage conditions.
Data Source
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AI summary
A method for providing phase synchronization to non-phase synchronized cellular base stations The method comprising at least one phase synchronized cellular base station having at least one transmit antenna for transmitting a signal to a at least one non-phase synchronized cellular base station, where it comprises transmitting by said at least one transmit antenna of said phased-synchronized cellular base station a beacon signal to said at least one non-phase synchronized cellular base station, included as part of said transmitted signal, said beacon signal comprising two orthogonal length-8 Walsh- Hadamard sequences to be broadcasted by said at least one phase synchronized cellular base station in order to provide said phase synchronization.