UCIe Sideband Priority Packet Switching for Low-Latency Alerts
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Solution Overview
Problem
Existing UCIe sideband protocols suffer from high latency in transmitting priority packets due to serialization and long packet lengths, which can exceed 640 ns, necessitating a mechanism for low-latency, urgent notifications without additional physical connections.
Innovation Solution
A priority packet optimization system that utilizes clock lane triggers to interrupt and resume data transfers at specific intervals, allowing priority packets to be sent without aliasing, and differentiates between urgent notifications using varying clock inactivity durations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If standard UCIe sideband protocols are used for priority packet transmission, then data integrity is maintained, but latency exceeds 640 ns due to serialization and long packet lengths
Solution Approach 1:
The patent segments the sideband link transmission into two distinct modes: normal packet mode for regular data and priority packet mode for urgent notifications. This segmentation allows the system to optimize each mode independently, with priority packets using a truncated, streamlined format that skips serialization overhead and transmits only essential bytes, thereby reducing latency to under 640 ns while maintaining data integrity through mode-specific protocols
Solution Approach 2:
The patent implements periodic clock inactivity detection as a trigger mechanism to switch between normal and priority transmission modes. The receiver monitors for clock inactivity periods, and when detected, automatically transitions to priority packet reception mode. This periodic monitoring and mode switching enables the system to rapidly respond to urgent notifications without requiring additional physical connections, effectively reducing latency while maintaining overall data transfer efficiency
2Speed
If additional physical connections are added for urgent notifications, then transmission speed improves, but device complexity increases
Solution Approach 1:
The patent makes the existing sideband link multi-functional by enabling it to operate in both normal packet mode and priority packet mode. The same physical clock and data lanes are used for both regular data transmission and urgent notifications. The receiver distinguishes between modes through clock inactivity detection, allowing the single sideband link to serve dual purposes without requiring additional physical connections, thus improving transmission speed for priority packets while avoiding increased device complexity
3Loss of time
If priority packets interrupt ongoing data transfers, then latency for critical events is reduced, but risk of aliasing increases
Solution Approach 1:
The patent introduces clock inactivity as an intermediary signal that mediates between ongoing data transfers and priority packet insertion. Before a priority packet can interrupt the data stream, the transmitter must first induce a clock inactivity period, which the receiver detects as a valid trigger. This intermediary mechanism ensures that priority packets are properly synchronized and delimited, preventing aliasing with the data lane while maintaining low latency for critical events through the interrupt capability
Data Source
AI summary
This disclosure describes systems, methods, and devices related to priority packet optimization. A device may receive a trigger indicating a switch to a high priority data transfer based on a clock signal remaining at a predetermined logic value for a defined number of unit intervals. The device may transmit a priority vector from a transmitter to a receiver, the priority vector comprising a plurality of bits, wherein a bit is transmitted during a respective clock cycle and a clock toggles during transmission. The device may receive a trigger indicating a resumption of a previous data transfer based on the clock signal again remaining at the predetermined logic value for the defined number of unit intervals. The device may format the priority vector as a sideband packet comprising an opcode and reserved fields before forwarding to upper protocol layers.