HID Virtual Endpoint Segmentation for Lower Polling Latency
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Solution Overview
Problem
Existing communication protocols for Human Interface Devices (HIDs) like computer mice and keyboards introduce latency due to the need for devices to wait for host polling, which limits the responsiveness of sensor data transmission.
Innovation Solution
Implementing multiple virtual endpoints for HIDs, allowing devices to send data using dummy packets when no new data is available, thereby increasing the polling rate without requiring faster communication channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the host polls the HID device at a standard frequency, then the communication protocol is stable and simple, but the latency is high and responsiveness is poor
Solution Approach 1:
The patent divides a single communication endpoint into multiple virtual endpoints (first virtual endpoint, second virtual endpoint, etc.). Each virtual endpoint can be polled independently at different frequencies, allowing the system to achieve higher effective polling rates by distributing polls across multiple segments rather than increasing the frequency of a single endpoint.
Solution Approach 2:
The patent implements dynamic polling where the host can adaptively select which virtual endpoint to poll based on data availability and timing. The system transitions from static single-frequency polling to dynamic multi-frequency polling across multiple endpoints, optimizing responsiveness without requiring uniformly high polling rates across all endpoints.
2Loss of time
If the host increases the polling frequency to reduce latency, then the responsiveness improves, but the bandwidth consumption and power usage increase
Solution Approach 1:
By segmenting the polling load across multiple virtual endpoints, the system can achieve higher effective polling rates without concentrating all polling traffic on a single channel. This distribution allows for more efficient use of available bandwidth and reduces peak power consumption compared to uniformly increasing the polling frequency of a single endpoint.
Solution Approach 2:
The patent implements periodic polling at different frequencies for different virtual endpoints. Instead of continuous high-frequency polling on all endpoints, the system uses staggered periodic polling where each endpoint is polled at optimized intervals, reducing overall power consumption while maintaining low latency through the combined effect of multiple periodic streams.
3Ease of operation
If the device waits for the next poll token to send data, then the communication protocol is simple, but the latency increases and responsiveness deteriorates
Solution Approach 1:
The patent segments the data transmission path into multiple virtual endpoints, allowing the device to have multiple active communication channels. When data becomes available, the device can immediately transmit on the next available virtual endpoint rather than waiting for a specific poll token sequence, significantly reducing waiting time while maintaining protocol simplicity.
Solution Approach 2:
The host preliminarily establishes multiple virtual endpoints during device initialization, preparing the communication infrastructure in advance. This preliminary setup allows the device to immediately utilize multiple channels for data transmission without waiting for protocol negotiation or endpoint creation at the time of data generation, reducing latency while keeping the runtime protocol simple.
Data Source
AI summary
A method and apparatus for wireless communications between a Human Interface Device (HID) and a host. The host receives a plurality of virtual endpoints for a single HID, and transmits multiple polling tokens to the virtual endpoints in each period. The HID responds either with sensor data, or dummy data when there is no new sensor data. The dummy data keeps the polling proceeding, allowing time for more sensor data to appear in the same period.