Secondary Synchronization Signals for Narrow-Band IoT

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Solution Overview

Problem

In cellular internet of things (CIoT) systems, wireless devices face synchronization challenges due to overlapping synchronization channel transmissions from neighboring devices, leading to misdetection and performance degradation.

Innovation Solution

The implementation of secondary synchronization signals (SSS) generated based on a logical identifier derived from a physical device ID and synchronization channel index, using pseudo-random functions to differentiate sequences and reduce persistent misdetections, alongside primary synchronization signals (PSS) in the synchronization channel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If synchronization channels are transmitted periodically by base stations, then frame, subframe, and symbol synchronization is achieved, but overlapping transmissions from neighboring base stations cause misdetection

Engineering Contradiction:

Improvesynchronization detection accuracyVSAvoidoverlapping transmissions from neighboring devices

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The synchronization channel is segmented into multiple distinct signals: primary synchronization signals (PSS) for basic synchronization and secondary synchronization signals (SSS) for enhanced identification. The SSS is further divided into first and second SSS components with different sequence patterns, allowing the receiver to distinguish between overlapping transmissions by analyzing which signal patterns are present

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sequence patterns are assigned to different SSS components to create locally distinguishable characteristics. The first SSS uses one set of sequence patterns while the second SSS uses another set, enabling the receiver to identify the specific base station and determine whether the received signal is from a neighboring device, thereby resolving the harmful overlapping effect

Inventive Principle:

Principle #3Local quality

2Reliability

If only primary synchronization signals are used, then device identification is simple, but persistent misdetections occur due to overlapping channels

Engineering Contradiction:

Improvesynchronization reliabilityVSAvoidsynchronization channel structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The synchronization channel structure is segmented into multiple functional components: PSS for initial synchronization and SSS for enhanced identification. The SSS is segmented into first and second parts with different sequence characteristics, providing multiple layers of identification without creating an unmanageably complex system

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the sequence parameters (root indices, sequence patterns) of the SSS signals to create distinguishable patterns. By varying these parameters across different SSS components and time instances, the system achieves reliable identification while maintaining manageable complexity through systematic parameter assignment

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If multiple synchronization channel instances are transmitted in a frame, then synchronization coverage is improved, but misdetection probability increases

Engineering Contradiction:

Improvesynchronization coverageVSAvoidsynchronization detection accuracy

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

Each synchronization channel instance is segmented into distinct SSS components with unique sequence patterns. This segmentation allows the receiver to analyze individual components and determine which base station transmitted which instance, enabling accurate identification even when multiple instances are present simultaneously

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses periodic transmission of synchronization channels with distinct temporal patterns. By combining periodic transmission with unique sequence patterns in the SSS, the system creates a two-dimensional differentiation mechanism that allows receivers to distinguish between multiple periodic instances based on both time and signal characteristics

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS9894626B2Secondary synchronization signals for a synchronization channel

Publication Date: 2018.02.13 QUALCOMM INC

AI summary

Methods, systems, and devices are described for wireless communication. The method may include determining, at a wireless device, a logical identifier (ID) as a pseudo-random function of a physical device ID of the wireless device and a synchronization channel index, where the synchronization channel index corresponds to an instance of a periodically repeating synchronization channel in a radio frame. The wireless device may be a base station in a serving cell, such that the synchronization channel may be to synchronize a downlink to communicate with a user equipment (UE) operating in a narrow-band cellular internet of things. The method may also include generating a secondary synchronization signal (SSS) for each instance of the periodically repeating synchronization channel in the frame based at least in part on the logical ID and the corresponding synchronization channel index, and transmitting the frame from the wireless device.