PMR Coexistence via Time-Division Multiplexing
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Solution Overview
Problem
Narrowband and broadband PMR devices experience significant radioelectric interference when in close proximity, leading to performance loss and making practical filtering difficult due to their adjacent frequency bands.
Innovation Solution
A method that coordinates the transmitting and receiving operations of narrowband and broadband PMR devices by detecting the presence of each other and reallocating frequency blocks through a control unit, using WPAN/WLAN technology for message exchange, and adjusting transmission periods to minimize interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If narrowband and broadband PMR devices operate in adjacent frequency bands, then both devices can function independently, but radioelectric interference occurs between them when located close to each other
Solution Approach 1:
The patent implements periodic time-division multiplexing where the broadband device transmits only during predefined allocated periods when no narrowband transmission is detected. The narrowband device transmits during other periods, creating a periodic alternation that eliminates continuous interference while allowing both devices to operate independently in the same frequency band.
2Object-affected harmful factors
If filtering means are added to reduce interference, then radioelectric disturbances are reduced, but device complexity and cost increase
Solution Approach 1:
Instead of adding physical filtering components, the patent changes the temporal parameter of transmission by implementing dynamic time-division multiplexing. The broadband device adjusts its transmission schedule based on detected narrowband activity, using parameter changes in the time domain rather than adding hardware filters in the frequency domain.
3Object-affected harmful factors
If minimum isolation between antennas is increased, then interference is reduced, but physical distance requirements increase device layout constraints
Solution Approach 1:
The patent uses periodic time-division multiplexing to allow narrowband and broadband devices to operate in close proximity without requiring large physical separation. By alternating transmission periods, the system achieves interference-free operation with minimal spatial isolation, removing constraints on device placement and antenna spacing.
Data Source
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AI summary
The present invention relates to a method for enabling radioelectric coexistence between two devices based on personal mobile radio or PMR technology, of which one is a narrow band device (10) and the other is a broadband device (20), and each device (10, 20) interacts via a radioelectric link with respective base stations (12, 22) connected to a control unit (16, 25) for the radio resource of their respective networks, characterized in that it comprises the following steps: - detection of the presence of a narrow band radioelectric emitter device in the vicinity of device (20), - transmission of a message on the broadband network, addressed to the control unit (25), which message signals the presence of a possible narrow band emitter close to said device (20), and - assignment by the control unit (25) of new frequency blocks for uplinks, only in predefined allocated periods.