Reconciliation Module for Multidrop Bus Collision Avoidance
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Solution Overview
Problem
Collisions on multidrop bus networks lead to decreased efficiency and throughput, as multiple nodes attempting to transmit data simultaneously result in corrupted data, time-outs, and loss of bus capacity.
Innovation Solution
A reconciliation module is introduced between the MAC and PHY modules in a node of a multidrop bus network, which asserts and de-asserts a sense signal to manage data transmission, preventing collisions by ensuring data is only transmitted during designated transmit opportunities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple nodes transmit data simultaneously on the multidrop bus network, then the bus utilization increases, but collisions occur causing data corruption and decreased throughput
Solution Approach 1:
The reconciliation module performs preliminary actions by asserting the sense signal before transmit opportunities and coordinating with the MAC module to prepare data for transmission. This preliminary coordination ensures that nodes are ready to transmit only when the bus is free, preventing collisions before they occur.
Solution Approach 2:
The reconciliation module acts as an intermediary between the MAC module and the PHY module, mediating the transmission process. It controls the sense signal and coordinates data flow, ensuring that transmission only occurs during designated opportunities when the bus is clear, thus preventing collisions while maintaining high utilization.
2Reliability
If the MAC module delays sending data by wait time after de-assertion of sense signal, then collision avoidance is improved, but transmission latency increases
Solution Approach 1:
The system uses periodic transmit opportunities with structured timing intervals. The wait time is synchronized with the periodic nature of transmit opportunities, allowing data to be transmitted at regular intervals when the bus is guaranteed to be free, balancing collision avoidance with acceptable latency.
Solution Approach 2:
The reconciliation module dynamically adjusts the timing parameters by controlling when the sense signal is de-asserted and when transmit opportunities occur. By optimizing these time parameters, the system achieves reliable collision avoidance while minimizing unnecessary delays in data transmission.
3Reliability
If the reconciliation module asserts sense signal continuously, then collision prevention is ensured, but bus efficiency decreases due to reduced transmit opportunities
Solution Approach 1:
The sense signal is asserted periodically rather than continuously, creating structured transmit opportunities at regular intervals. This periodic assertion maintains collision prevention by ensuring the bus is reserved at key moments while allowing efficient data transmission during the designated opportunity windows.
Solution Approach 2:
The sense signal is asserted in advance of transmit opportunities to preliminarily reserve the bus for upcoming transmissions. This preliminary assertion ensures collision-free transmission windows are established before data needs to be sent, maintaining both reliability and efficiency.
Data Source
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AI summary
A reconciliation module for a node of a multidrop bus network, the node comprising a MAC module and a PHY module, the reconciliation module comprising circuitry configured to: assert a sense signal until the beginning of each transmit opportunity of the node; de-assert the sense signal at that moment to cause the MAC module to send available data to the reconciliation module to start transmission of the data on the multidrop bus network via the PHY module at the respective transmit opportunity; and re-assert the sense signal on receipt of the data from the MAC module or time-out of the respective transmit opportunity.