Non-Discoverable Public Safety UE Synchronization
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Solution Overview
Problem
Public safety UEs operating outside network coverage face challenges in synchronization and discovery, particularly for non-discoverable devices, as they cannot receive synchronization information from the network.
Innovation Solution
A method where non-discoverable public safety UEs transmit synchronization information without identifying themselves, allowing other devices to synchronize and enabling Proximity Announcements to be received, while maintaining anonymity, and using a Universal Public Safety Clock and reserved spectrum bands for synchronization and communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-discoverable PS UEs do not transmit their identities, then their anonymity is maintained and they cannot be discovered by other PS UEs, but other PS UEs cannot synchronize with them and discoverability is lost
Solution Approach 1:
The transmission function is segmented into two separate signals: synchronization information (transmitted to enable timing coordination) and identity information (omitted to maintain anonymity). This allows the non-discoverable UE to participate in synchronization without revealing its identity, resolving the contradiction between reliability and discoverability.
Solution Approach 2:
A pseudo-synchronization signal acts as an intermediary carrier that conveys only timing information without identity data. This mediator enables other PS UEs to synchronize with the non-discoverable UE while the UE itself remains anonymous and undiscoverable, balancing both requirements.
2Adaptability or versatility
If PS UEs operate outside network coverage, then communication autonomy is improved, but synchronization capability deteriorates as they cannot receive synchronization information from the network
Solution Approach 1:
PS UEs broadcast synchronization information proactively even when out of network coverage, before other UEs need to synchronize with them. This preliminary action ensures that timing information is available to other devices, maintaining synchronization reliability while preserving operational autonomy.
Solution Approach 2:
Out-of-coverage PS UEs independently generate and broadcast their own synchronization signals without requiring network assistance. This self-service capability enables them to maintain timing synchronization autonomously, resolving the contradiction between operational autonomy and synchronization reliability.
3Difficulty of detecting and measuring
If PS UEs transmit Proximity Announcements continuously, then discovery capability is improved, but energy consumption increases
Solution Approach 1:
PS UEs transmit Proximity Announcements periodically rather than continuously, using time-slot based transmission. This periodic action reduces energy consumption by keeping the transmitter inactive between slots while still enabling reliable discovery when needed, resolving the contradiction between discovery capability and energy consumption.
Data Source
AI summary
The disclosure relates to a method for discovery by a non-discoverable first public safety user equipment (PS UE), of a discoverable second PS UE in a public safety system comprising a telecommunications network providing a public safety spectrum for wireless access of the first PS UE and the second PS UE. The method can comprise for the first non-discoverable PS UE: transmitting synchronization information for the second PS UE; receiving at least one proximity announcement from the second PS UE in accordance with the transmitted synchronization information. The disclosure also relates to a non-discoverable public safety user device configured for performing the method, and relates to a PS server system arranged for assisting in the discovery of PS UEs.