In-Payload Arbitration for CAN Bus Latency Control

The payload portion of the data frame is divided into multiple segments by inserting arbitration fields at specific boundaries. This segmentation allows the frame to be transmitted in chunks with periodic arbitration opportunities, enabling high-priority frames to preempt low-priority transmissions without requiring the entire frame to be sent continuously. The payload segmentation resolves the contradiction by allowing large data transmission capacity while maintaining low latency through periodic arbitration points.

Arbitration fields are inserted periodically within the payload portion at defined boundaries (e.g., after every N bytes). These periodic arbitration opportunities create windows where bus control can be contested, ensuring that even if a low-priority node starts transmission, high-priority nodes can regain control at the next arbitration boundary. This periodic structure enables large payload sizes while guaranteeing bounded latency for high-priority traffic.

The payload is segmented with arbitration fields inserted at boundaries, creating multiple transmission phases. Each phase transmits a portion of the payload before allowing arbitration. This reduces the duration any single node can monopolize the bus, limiting maximum frame transmission duration while maintaining overall efficiency through continued transmission in subsequent phases if the node wins arbitration.

The transmission duration becomes dynamic rather than fixed. A node transmitting a large payload can continue transmission across multiple arbitration intervals if it maintains arbitration wins, adapting the actual transmission duration to real-time priority conditions. This dynamic behavior allows efficient large数据传输 when needed while preventing excessive latency when high-priority traffic arrives.

The arbitration field serves multiple functions simultaneously: it acts as a bus control mechanism for arbitration, a structural delimiter for payload segmentation, and a priority assertion point for high-priority frames. By making the arbitration field multi-functional, the patent reduces the need for separate control structures, thereby limiting the increase in frame structure complexity while achieving latency reduction.

The payload portion itself provides the arbitration mechanism by incorporating arbitration fields at its boundaries. Rather than requiring a separate control structure outside the payload, the payload's own structure enables arbitration functionality. This self-service approach minimizes additional structural complexity while achieving the latency benefits of frequent arbitration opportunities.

Arbitration fields are inserted locally at specific boundaries within the payload portion rather than uniformly throughout. The boundaries are determined by predefined criteria (e.g., after specific byte counts or data types). This localized approach concentrates arbitration opportunities where they are most effective for preventing bus domination, reducing the overall number of arbitration fields needed and thereby limiting protocol complexity increase while maintaining latency control.

Arbitration fields are inserted at sufficient boundaries to prevent bus domination by low-priority nodes, but not at every possible position. The insertion follows a partial action principle by placing fields at strategically chosen boundaries that provide adequate arbitration opportunities without over-engineering the protocol. This balances latency control requirements with protocol simplicity.