Token Bus Packet With Dual Address Fields
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Solution Overview
Problem
Token bus communication systems face challenges in achieving improved responsiveness, data throughput, and determinism, particularly in subsea environments where conflict arbitration and efficient data transfer are critical.
Innovation Solution
Incorporating a second address field in the packet header to specify the node receiving the token, allowing simultaneous transmission of data and token packets, which ensures each node has a share of bandwidth and reduces contention by relying on higher-level protocols for acknowledgement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a node transmits data packets sequentially with token passing, then data integrity is maintained, but data throughput and responsiveness are reduced
Solution Approach 1:
The patent combines data transmission and token passing into a single integrated packet structure. The token is embedded within the data packet itself, allowing the receiver to immediately forward both the data and token in one operation, thereby eliminating sequential delays and improving throughput while maintaining data integrity through the structured packet format.
2Reliability
If acknowledgements are transmitted for each packet, then data transfer reliability is improved, but bus contention and transmission overhead increase
Solution Approach 1:
The patent extracts the acknowledgement function from separate transmission events and integrates it into the token-passing mechanism itself. The token serves as both a control signal for bus access and an implicit acknowledgement of received data, eliminating redundant acknowledgement packets and reducing bus overhead while maintaining reliability through the structured token validation process.
3Speed
If the token is passed to the next node immediately after receipt, then system responsiveness is improved, but bandwidth allocation fairness may be compromised
Solution Approach 1:
The patent implements a periodic token-passing cycle where each node receives the token in turn according to a predetermined sequence. This periodic structure ensures that every node gets a guaranteed time slot for transmission, maintaining fairness in bandwidth allocation while the immediate forwarding requirement keeps the system responsive by preventing token hoarding and minimizing idle bus time.
Data Source
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AI summary
In a token bus system a node with the token can transmit on the bus a packet (90) that contains two destination addresses. One address specifies the node that should receive the data component (payload) of the transmitted packet. The other address specifies the node that should receive the token. The network protocol specifies that a node with the token must immediately transmit a packet (80) containing just the token or a packet (90) with token and data if it has data to send. When no data is being passed from one node to another on the network, the token may be passed from one node to the next in order. Each node will pass the token to the next highest node number. If a node has the token has some data for sending it transmits a packet with the token for the next node and data for any of the nodes. The bus system requires every node to receive all packets and process them to determine whether the token or the data (or both) is destined for that node.