Virtual LMR Network Integration via ISSI Protocol Translator

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Solution Overview

Problem

Existing methods for integrating Land Mobile Radio (LMR) systems with cellular networks face issues such as mismatched audio quality, incompatible feature sets, and loss of end-to-end encryption due to different protocols on either side of the gateway, limiting seamless communication across both technologies.

Innovation Solution

A virtual LMR network is established on an IP network connected via Inter RF Subsystem Interface (ISSI) to a physical LMR network, allowing for the creation of virtual LMR channels that can supplement existing RF channels, enabling multi-bearer devices to communicate seamlessly using both LMR and IP bearers, and extending coverage by combining LMR and cellular networks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a gateway is used to integrate LMR and cellular networks, then communication between the two networks is enabled, but protocol mismatches cause audio quality degradation, feature incompatibility, and loss of end-to-end encryption

Engineering Contradiction:

Improvenetwork integration capabilityVSAvoidaudio quality and encryption

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces a protocol translator as an intermediary component that sits between the LMR network and cellular network. This translator converts LMR protocols into IP-compatible protocols, enabling communication while maintaining audio quality and encryption. The translator acts as a smart mediator that understands both protocol stacks and preserves critical features during translation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system segments the integration function into separate components: the LMR network side, the protocol translator, and the cellular network side. This segmentation allows each component to operate independently with its optimized protocol, avoiding the need for a single gateway that compromises both sides. The protocol translator handles only the protocol conversion task, preserving audio quality and encryption in their respective domains.

Inventive Principle:

Principle #1Segmentation

2Area of stationary object

If LMR systems operate over wide areas including unpopulated areas, then coverage is extended, but cellular infrastructure is unavailable in these areas

Engineering Contradiction:

Improvecoverage areaVSAvoidbearer availability

Core Design Contradiction:

Area of stationary objectVSAdaptability or versatility

Solution Approach 1:

The system dynamically selects the appropriate communication bearer based on availability. In unpopulated areas where cellular infrastructure is absent, the system automatically uses LMR bearers. In populated areas where cellular infrastructure exists, the system can use cellular bearers. This dynamic adaptation allows continuous coverage across both wide and populated areas without service interruption.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The communication system is designed to support multiple bearers (both LMR and cellular) within a single unified framework. This multi-functionality allows the system to operate over LMR in unpopulated areas and switch to cellular in populated areas, providing universal coverage across diverse geographic conditions without requiring separate systems.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Speed

If cellular systems are deployed over populated areas for revenue generation, then data rates are high, but coverage in unpopulated areas is lost

Engineering Contradiction:

Improvedata rateVSAvoidcoverage area

Core Design Contradiction:

SpeedVSArea of stationary object

Solution Approach 1:

The service area is segmented into different zones: populated areas with cellular infrastructure and unpopulated areas with only LMR infrastructure. The system automatically routes traffic through the appropriate network based on location. This segmentation allows cellular to provide high-speed data in populated areas while LMR provides coverage in unpopulated areas, eliminating the need to choose between speed and coverage area.

Inventive Principle:

Principle #1Segmentation

4Reliability

If tunneling LMR within IP is used to avoid protocol mismatches, then audio quality and encryption are preserved, but the solution is limited to specific core network implementations

Engineering Contradiction:

Improveaudio quality and encryptionVSAvoidnetwork compatibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent employs a protocol translator as an intermediary that can adapt to different core network implementations. Rather than relying on a specific tunneling implementation tied to one manufacturer, the translator provides a standardized interface that works across multiple network types. This intermediary approach preserves audio quality and encryption while improving adaptability to various network implementations.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10516553B2Integration of physical and virtual LMR networks

Publication Date: 2019.12.24 TAIT INT LTD

AI summary

Integration of a land mobile radio (LMR) communications system and other wireless IP based systems such as LTE by way of a virtual router and virtual base stations. The LMR system may be either trunked or conventional. The virtual router maintains LMR IDs and also IP addresses for both physical and virtual base stations, multi bearer terminals and other components of the integrated system. Physical LMR base stations form a physical network. Virtual LMR base stations form a virtual network. These physical and virtual LMR networks communicate using ISSI, AIS or DFSI for example.