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 the multidrop bus network. This module receives data from the MAC module, asserts a sense signal, and delays the de-assertion of the sense signal after transmission to facilitate further data transmission at the next transmit opportunity, thereby avoiding collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple nodes transmit data simultaneously on the bus, then data transmission throughput increases, but collisions occur causing decreased bus efficiency and throughput
Solution Approach 1:
The reconciliation module performs preliminary actions by asserting the sense signal before data transmission and maintaining it asserted during transmission. This preliminary carrier sense setup ensures that the MAC module only transmits when the bus is truly idle, preventing collisions before they occur while allowing efficient use of transmission opportunities.
Solution Approach 2:
The reconciliation module implements feedback by continuously monitoring the sense signal state and adjusting the transmission timing accordingly. The module uses the sense signal to provide feedback to the MAC module about bus occupancy status, enabling dynamic adaptation to avoid collisions while maximizing throughput.
2Productivity
If the sense signal is de-asserted immediately after transmission, then the MAC module can quickly prepare for re-transmission, but collisions may occur if another node transmits in the same opportunity
Solution Approach 1:
The reconciliation module delays de-assertion of the sense signal until after the next transmit opportunity has passed or a predefined wait time has elapsed. This preliminary preparation ensures that the MAC module cannot initiate re-transmission until the bus is confirmed idle, preventing collisions while maintaining efficient re-transmission timing.
Solution Approach 2:
The reconciliation module acts as an intermediary between the MAC module and the bus. It mediates the timing between data transmission and sense signal de-assertion, ensuring that the MAC module's re-transmission attempts are coordinated with actual bus availability to prevent collisions.
3Reliability
If the sense signal is held asserted during the MAC module's wait time, then collisions are avoided, but the MAC module's re-transmission timing may be delayed
Solution Approach 1:
The reconciliation module performs preliminary actions by asserting the sense signal before the MAC module's wait time begins and maintaining it asserted throughout the wait period. This ensures collision avoidance is built into the timing structure itself, while the module is configured to de-assert the sense signal at the optimal moment to minimize re-transmission delay.
Solution Approach 2:
The reconciliation module changes the timing parameter of the sense signal de-assertion based on the MAC module's wait time configuration. By dynamically adjusting when the sense signal is de-asserted relative to the wait time and transmit opportunities, the system optimizes both collision avoidance and re-transmission speed.
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: receive data from the MAC module for transmission on the multidrop bus network via the PHY module at a transmit opportunity of the node; assert a sense signal on receipt of the data from the MAC module; and delay de-assertion of the sense signal after transmission of the data to facilitate the transmission of further data at the next transmit opportunity of the node.