SAS Expander Link Layer Signal Segmentation
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Solution Overview
Problem
SAS expanders face challenges in maintaining performance while reducing complexity and size due to large parallel bus structures used for interconnect signals between link layer control circuits and connection managers.
Innovation Solution
Segmenting interconnect signals into portions and transmitting them sequentially over a smaller parallel bus structure, utilizing known processing delays to establish SAS connections, thereby reducing the size and complexity of the bus structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If large parallel bus structures are used to transmit all interconnect signals simultaneously between link layer control circuits and connection manager, then real-time signal exchange and connection establishment performance are improved, but circuit complexity and die area increase significantly
Solution Approach 1:
The patent segments the large set of interconnect signals into multiple smaller groups or subsets. Each subset is transmitted separately over the parallel bus structure at different times. This segmentation reduces the number of simultaneous signal paths required, thereby reducing bus structure complexity and die area while maintaining connection establishment performance through sequential transmission
Solution Approach 2:
The patent employs periodic transmission of signal subsets over the parallel bus structure. Instead of transmitting all interconnect signals simultaneously, the system transmits different subsets in successive time periods or clock cycles. This periodic action allows the use of a smaller bus structure while maintaining real-time signal exchange capability across multiple transmission cycles
2Reliability
If large parallel bus structures are used to transmit all interconnect signals simultaneously, then real-time signal exchange is achieved, but die area and package size increase
Solution Approach 1:
The patent divides the complete set of interconnect signals into multiple smaller subsets that are transmitted sequentially. Each subset requires fewer simultaneous signal paths, reducing the required die area for the bus structure. The segmentation maintains real-time signal exchange capability by ensuring that each necessary signal subset is transmitted within acceptable time frames
Solution Approach 2:
The patent performs preliminary segmentation of interconnect signals into manageable subsets before transmission. This preliminary organization allows the system to use a smaller bus structure while ensuring that all necessary signals are transmitted in the correct sequence and time frame to maintain real-time operation
Data Source
AI summary
Methods and systems for reducing the signal path count between circuits within a SAS expander used for establishing SAS connections. The system comprises a SAS expander. The SAS expander comprises a plurality of link layer control circuits, each link layer control circuit adapted to communicatively couple with a SAS device. The SAS expander further comprises a connection manager communicatively coupled with the link layer control circuits for routing communications between the link layer control circuits. Each of the plurality of link layer control circuits is adapted to establish a SAS connection with another link layer control circuit through the connection manager by segmenting a plurality of interconnect signals into multiple data segments for sequential transmission to the connection manager, (e.g., without impacting the performance of the connection manager). The connection manager interprets the data segments to extract the plurality of interconnect signals to establish the SAS connection.