Dual Simplex Link for DisplayPort Range Extension
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Solution Overview
Problem
The DisplayPort specification is limited by a half-duplex protocol that restricts bi-directional control signal communication over a single medium, leading to timeouts if responses are not received within 300 microseconds, and existing solutions fail to address the range limitations and timing requirements for effective communication between a computer host and a display device.
Innovation Solution
A method and system utilizing a dual simplex communications link with a local and remote unit to manage request and reply packets, including storing requests and replies in queues and using synthetic defer commands to prevent timeouts, allowing for extended communication ranges and improved bi-directional communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a half-duplex protocol is used for bi-directional control signal communication, then the communication medium is simplified, but the communication range is limited due to timeout requirements
Solution Approach 1:
The patent divides the communication link into two separate simplex channels (first simplex channel for host-to-display, second simplex channel for display-to-host), allowing simultaneous bidirectional communication without timeout constraints on either direction, thus extending the effective communication range while maintaining protocol simplicity
Solution Approach 2:
The patent transitions from a single-medium half-duplex communication to a dual-channel simplex communication architecture, adding a temporal dimension by allowing overlapping transmissions in opposite directions, thereby eliminating the timeout limitation that constrained the original single-medium approach
2Device complexity
If a single common communication medium is used for bi-directional control signals, then the system is simplified, but timeouts occur when responses are not received within 300 microseconds
Solution Approach 1:
The patent segments the bidirectional communication into two independent simplex channels, allowing the host and display to transmit simultaneously without interfering with each other's timeout counters, thereby improving communication reliability while keeping the overall system architecture relatively simple
Solution Approach 2:
The patent introduces intermediary processing at each endpoint that buffers and manages the timing of control signals and responses, allowing flexible timing accommodation and preventing timeouts by mediating between the two communication directions
3Device complexity
If the DisplayPort specification timeout requirement is enforced, then the protocol is simplified, but the permitted range between host and display is limited
Solution Approach 1:
The patent applies segmentation by separating the communication path into two independent simplex channels, allowing each direction to have its own timeout mechanism and effectively doubling the permitted communication range by eliminating the single 300microsecond timeout constraint
Solution Approach 2:
The patent changes the communication parameter from half-duplex to dual simplex mode, fundamentally altering the timing characteristics and allowing extended communication ranges by removing the strict 300microsecond timeout limitation that applied to the original protocol
Data Source
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AI summary
A system and method for communicating DisplayPort information is provided. The system includes: a local unit comprising a local controller operable to produce a request packet in response to a DisplayPort request received by the local unit from a DisplayPort source unit and to transmit the request packet to a remote unit of the system via a first simplex channel of a dual simplex communications link; and the remote unit comprising a remote controller operable to produce a reply packet in response to a DisplayPort reply received by the remote unit from a DisplayPort sink unit and to transmit the reply packet to the local unit via a second simplex channel of the communications link. The system allows distances between the source and sink greater than otherwise possible under the DisplayPort specification, and can communicate DisplayPort and non-DisplayPort signals via a variety of types of communications links.