Optical Interconnect Collision Detection Without Arbiters
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Solution Overview
Problem
In parallel processing systems with multiple microprocessors, the increased I/O bandwidth requirements and need to share information among processors lead to data collisions, which existing technologies struggle to detect efficiently without separate arbiters, affecting transmission bandwidth and latency.
Innovation Solution
An optical data interconnect system with multiple nodes that uses optical collision detection channels to monitor for transmission collisions by transmitting a first collision detect signal and identifying a second collision signal within a predetermined period, allowing for timely retransmissions and minimizing additional bandwidth requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate arbiters are used to detect data collisions, then collision detection reliability is improved, but device complexity and bandwidth requirements increase
Solution Approach 1:
The patent implements self-service by enabling nodes to autonomously detect collisions through their own transmission activities. When a node transmits a data signal, it simultaneously monitors for collision signals on the optical interconnect without requiring external arbiter assistance. The node identifies collisions by detecting specific optical patterns (e.g., absence of expected return signals or presence of collision-indicating signals) during its transmission window, thereby making each node self-sufficient in collision detection.
Solution Approach 2:
The patent applies universality by designing the optical interconnect to serve multiple functions simultaneously. The same optical channel that transmits data signals also carries collision detection information bidirectionally. Each optical link functions both as a data transmission medium and as a collision detection channel, eliminating the need for separate arbitration infrastructure and reducing overall system complexity.
2Measurement precision
If separate arbiters are used to detect data collisions, then collision detection accuracy is improved, but transmission bandwidth is reduced
Solution Approach 1:
The patent merges collision detection functionality into the existing data transmission infrastructure. The collision detection process utilizes the same optical channels, transmitters, and receivers that handle data communication. By combining these functions, the system avoids dedicating separate bandwidth for arbitration while maintaining accurate collision detection through the integration of detection logic within the data path.
Solution Approach 2:
Nodes perform self-detection of collisions by monitoring their own transmission channels during active communication. This self-service approach eliminates the need for external arbitration traffic, preserving full bandwidth for data transmission while achieving accurate collision detection through autonomous node monitoring and analysis of optical signal characteristics.
3Reliability
If nodes wait for permission before transmitting, then collision probability is reduced, but transmission latency increases
Solution Approach 1:
The patent implements feedback mechanisms where nodes continuously monitor the optical interconnect for collision signals during and after transmission attempts. When a node transmits data, it receives feedback in the form of collision indicators (such as absence of expected acknowledgment signals or presence of specific collision patterns) that inform whether the transmission was successful or if a collision occurred, enabling rapid retransmission decisions without lengthy arbitration delays.
Solution Approach 2:
Nodes perform preliminary collision detection by monitoring the optical channel before and during transmission initiation. The system detects collision conditions in advance or during the transmission window, allowing nodes to identify and handle collisions promptly without waiting for post-transmission arbitration, thereby reducing latency while maintaining collision avoidance reliability.
Data Source
AI summary
A method of detecting transmission collisions in an optical data interconnect system. The method includes initiating a data transmission of a data signal from a transmitting node over the optical data channel, transmitting a first collision detect signal from the transmitting node throughout a duration of the data transmission where the first collision detect signal is transmitted over an optical detection channel corresponding to the transmitting node, monitoring at the transmitting node of the optical data interconnect system for a predetermined period of time, where the optical data interconnect system further includes optical collision detection channels corresponding to each of a plurality of receiving nodes and one or more remaining nodes, and identifying a transmission collision when a second collision signal is received through one of the optical collision detection channels at the transmitting node during the predetermined period of time.