USB Extension Device Maintaining Timing Synchronization
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Solution Overview
Problem
USB communication over longer distances faces challenges due to variable latency in receiving start-of-frame packets, which can disrupt synchronization between host and device, especially in applications requiring precise timing like streaming media.
Innovation Solution
A system with upstream and downstream facing ports that receive and adjust timing signals to match the host's timing signal generation rate, using a network to extend USB communication distances while maintaining synchronization by monitoring and adjusting the transmission rate of local timing signals based on received remote timing signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If USB communication is extended over longer distances using network infrastructure, then communication distance is increased, but timing synchronization between host and device deteriorates due to variable latency in receiving start-of-frame packets
Solution Approach 1:
The patent introduces an intermediary device (USB extension device or hub) that sits between the host and the USB device. This intermediary receives timing signals from the host, processes them locally, and generates new timing signals for the USB device. The intermediary acts as a mediator that decouples the timing relationship between host and device, allowing extended communication distance while maintaining synchronization reliability through local timing signal generation rather than direct transmission over the extended network distance
Solution Approach 2:
The patent segments the USB communication system into distinct sections: the host controller, the USB extension device (intermediary), and the USB device. Each segment handles timing independently - the host generates timing signals, the extension device processes and regenerates them, and the device receives them. This segmentation allows the timing-critical portions to remain localized while the non-critical communication path can be extended over longer distances through the network infrastructure
2Adaptability or versatility
If start-of-frame packets are transmitted over extended distances through network infrastructure, then communication flexibility is improved, but timing precision deteriorates due to variable latency affecting the rate at which packets are received by the USB device
Solution Approach 1:
The USB extension device performs preliminary action by receiving timing signals from the host and processing them in advance before forwarding to the USB device. The extension device anticipates timing requirements by maintaining a local timing base and pre-generating appropriately timed timing signals, ensuring that even though communication paths are extended and flexible, the timing precision required by the USB device is maintained through advance preparation of timing signals
Solution Approach 2:
The patent employs copying by having the USB extension device receive timing signals from the host, analyze their timing characteristics, and then create (copy) new timing signals that replicate the essential timing properties. This copying process allows the system to maintain accurate timing relationships despite the physical distance and network variability, as the copied timing signals are generated locally with precise timing rather than being directly transmitted over the variable-latency network path
Data Source
AI summary
Devices and methods for generating timing signals at a rate that matches a rate of remotely generated timing signals are provided. In some embodiments, a host generates timing signals in accordance with a USB specification, such as keep-alives, start-of-frame packets, or ITPs. An upstream facing port transmits the timing signals over a network to a downstream facing port. The downstream facing port generates and transmits timing signals to a USB device at a predetermined rate, and alters the predetermined rate based on an analysis of the rate at which timing signals are received from the upstream facing port.