USB Extension Device Bus Interval Timing Management
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Solution Overview
Problem
Existing USB technologies face limitations in extending SuperSpeed connections beyond the 3-meter distance due to timing and signaling requirements, necessitating new techniques to maintain synchronization and communication reliability over longer distances.
Innovation Solution
The implementation of a USB extension system using upstream and downstream extension devices that manage bus interval messages across an extension medium, adjusting for latency variations by establishing expected times of receipt and using soft and hard thresholds to ensure timely transmission of outgoing bus interval messages, thereby maintaining synchronization with the host device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If USB extension devices are used to extend SuperSpeed connections beyond 3 meters, then communication distance is improved, but timing synchronization and communication reliability deteriorate due to latency variations
Solution Approach 1:
The downstream USB extension device implements feedback by determining an expected time of receipt for incoming bus interval messages and comparing it with the actual reception time. Based on this feedback loop, the device dynamically adjusts the transmission time of outgoing bus interval messages to compensate for latency variations in the extension medium, thereby maintaining timing synchronization and communication reliability over extended distances
Solution Approach 2:
The patent changes the timing parameter of outgoing bus interval messages based on measured latency. The downstream device calculates a time difference between expected and actual reception times, then adjusts the transmission time of outgoing messages by this difference, effectively adapting the communication timing parameters to the specific latency characteristics of the extended connection medium
2Length of stationary object
If USB extension devices are used to extend SuperSpeed connections beyond 3 meters, then communication distance is improved, but timing synchronization deteriorates due to latency-induced timing errors
Solution Approach 1:
The downstream USB extension device performs preliminary action by determining the expected time of receipt of incoming bus interval messages in advance. This allows the device to proactively calculate the required adjustment to outgoing message transmission times before actual timing errors occur, maintaining synchronization by preemptively compensating for known or anticipated latency variations
Solution Approach 2:
The patent dynamically changes the transmission time parameter of outgoing bus interval messages based on the calculated difference between expected and actual reception times. This parameter adjustment ensures that timing synchronization is maintained despite the extended cable length and associated latency variations
Data Source
AI summary
Techniques for generating bus interval messages by a downstream USB extension device in a USB extension environment are disclosed. The downstream USB extension device transmits a first outgoing bus interval message in response to receiving a first incoming bus interval message at a first time. An expected time of receipt of a second incoming bus interval message is determined based on the first time. The downstream USB extension device transmits a second outgoing bus interval message at a second time based on a difference between the reception time and the expected time of receipt if the second incoming bus interval message has been received at a reception time before the expected time of receipt. The downstream USB extension device transmits the second outgoing bus interval message at the expected time of receipt if the second incoming bus interval message has not been received before the expected time of receipt.