OPC UA Mobile Energy Optimization via Server Push
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Solution Overview
Problem
The OPC UA protocol's request-response based communication mechanism is energy inefficient for mobile devices, leading to rapid battery discharge due to constant transmitter activation, as it was not designed to account for mobile communication needs, resulting in devices being unable to efficiently react to rare warnings or events without frequent polling.
Innovation Solution
Implementing a push service mechanism that allows the OPC UA server to trigger notifications to the client only when data is available, eliminating the need for continuous connection and reducing energy consumption by using a mobile push service to wake up the client for event notifications, thus minimizing active antenna time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the client sends periodic publish requests to the server to maintain connection and retrieve data, then the connection remains active and data can be retrieved, but the transmitter must be frequently activated leading to high energy consumption
Solution Approach 1:
The patent inverts the traditional client-initiated request-response model by allowing the server to push notifications to the client. The server sends a publish response with a sequence number, and the client only needs to send a single request to acknowledge receipt. This reversal eliminates the need for periodic client polling while maintaining connection stability and ensuring data delivery.
Solution Approach 2:
The patent introduces an acknowledgment mechanism as an intermediary step between server notification and client data retrieval. The client sends an acknowledgment request with the received sequence number, which serves as a mediator to confirm data receipt without requiring continuous polling. This intermediary mechanism enables event-driven communication while maintaining reliable delivery.
2Speed
If the client sends frequent publish requests to ensure timely receipt of warnings or events, then response time to events is reduced, but battery life is significantly reduced due to constant transmitter activation
Solution Approach 1:
The patent replaces continuous periodic polling with event-triggered periodic action. Instead of the client sending requests at fixed intervals, the server initiates communication only when data is available for transmission. The client then responds with a single acknowledgment request. This transforms continuous periodic action into event-driven action, maintaining responsiveness while dramatically reducing transmitter activation frequency.
Solution Approach 2:
The server performs preliminary action by maintaining the connection and preparing data for transmission. When data is ready, the server proactively pushes the publish response to the client before the client would have polled for it. This preliminary action by the server eliminates the need for the client to repeatedly query, ensuring timely event delivery while conserving client energy.
3Adaptability or versatility
If the client uses standard OPC UA request-response mechanism, then protocol compliance is maintained, but energy efficiency for mobile devices is poor due to frequent keep-alive messages
Solution Approach 1:
The patent changes the communication parameters by modifying the initiation direction and frequency of messages. Instead of the client sending keep-alive requests at regular intervals, the server sends publish responses only when data is available. The client's parameter changes from periodic initiator to event-driven responder, sending acknowledgments only in response to server notifications. This parameter change maintains OPC UA protocol compliance while optimizing for mobile device energy efficiency.
Data Source
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AI summary
When using OPC UA communication on a mobile device, for example, as mobile access to a plant component for maintenance, monitoring, parameterization, etc., the request-response-based communication behavior of OPC UA results in frequent transmissions. Since the device rarely has the opportunity to switch off the transmitter, its battery is drained very quickly. This poses a particular problem for devices that need to react promptly to infrequent warnings or events. However, if a client device is only to be notified of a single event, the previous polling (periodic querying) is omitted, and an alternative notification method using the mobile network's inherent capabilities is employed. This method utilizes, for example, a mobile push service, which must be provided by the network operator.