IEEE 1394 Request Signal Priority Control for Critical Data Transfer
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Solution Overview
Problem
The IEEE 1394 communication protocol, used in multimedia environments, faces challenges in prioritizing data transfers, particularly when nodes with varying data receiving capabilities are connected, leading to reduced system efficiency and inability to ensure immediate and timely high-priority data transfer, especially in applications like machine control or automobile LANs.
Innovation Solution
A data transfer device with a request signal generation circuit that generates request signals with different priority levels, a determination circuit to identify the highest priority signal, and a top priority request signal generation unit, which includes a priority determination table setting the top priority signal higher than existing signals, allowing for immediate and prioritized data transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the IEEE 1394 protocol uses standard priority levels for bus requests, then non-biased communication is guaranteed among nodes, but high-priority data transfer cannot be ensured when critical applications like machine control require immediate transmission
Solution Approach 1:
The patent introduces a new request command type (request command 0) that changes the priority parameter of bus requests from the standard IEEE 1394 levels to a highest priority level. This allows critical data transfer to preempt other transmissions by modifying the priority parameter assigned to bus requests, while non-critical transmissions continue to use standard priority levels, thus maintaining communication fairness for general purposes while enabling urgent data transfer when needed
2Productivity
If a node issues a bus request during ongoing data transfer in half-duplex mode, then the request is queued until transfer completion, but this causes unnecessary delay for high-priority data
Solution Approach 1:
The patent makes the bus request priority dynamic rather than static. When a node has critical data to transfer, it issues a bus request with request command 0, which dynamically assigns the highest priority level. This dynamic priority adjustment allows the system to respond to changing conditions - during normal operation, standard queuing maintains bus utilization, but when high-priority data arrives, the priority structure dynamically changes to allow immediate transmission by preempting lower-priority requests
3Adaptability or versatility
If data is transferred to nodes with low receiving capability in isochronous mode, then the transfer rate is limited by the slowest node, but this reduces overall system data transfer efficiency
Solution Approach 1:
The patent segments data transfer into two separate channels: isochronous transfer for nodes with low receiving capability and asynchronous transfer for high-speed data transfer. By dividing the data stream and routing different portions through different transfer modes, the system can maintain compatibility with slower nodes (who receive their appropriate data portion via isochronous transfer) while simultaneously achieving high overall system productivity through asynchronous transfer of remaining data that does not require strict timing constraints
Data Source
AI summary
A data transfer device arranged in a node for connection in compliance with a communication standard. The data transfer device includes a request signal generation circuit for generating request signals defined by the communication standard with different levels of priority. A determination circuit determines the request signal having the highest level of priority. Priority is given to the transfer of data corresponding to the request signal determined to have the highest level of priority by the determination circuit. A top priority request signal generation unit generates a top priority request signal that differs from the request signals defined by the communication standard. The determination circuit includes a priority determination table in which the uppermost priority request signal is set to have a level of priority that is higher than the levels of priority of the plurality of existing request signals.