High Speed Synchronous Interface Working Group

The HSI Working Group's task was to improve the MIPI Baseband-Application interface solution by updating the Legacy HSI 1.0 specification.

A key target was to maintain backward compatibility with HSI 1.0. The group provided improvements and corrections to the specification while keeping concepts or fundamental changes out of scope. Also, only physical layer remains in HSI 1.1 specification while there are no longer requirement for a specific protocol layer, it may implement proprietary protocols if desired.”

HSI is an interface designed to connect an application die to a cellular modem die in cellular handsets, but also can be used for other purposes.
HSI provides a multi-processor (or more broadly said on-chip-interconnect) low-latency communication channel over a die-to-die link by dividing the physical link to logical channels at the hardware level. HSI enables versatile, easy and simple serial link realizations. As such, HSI can reduce time-to-market and design cost of mobile handsets by simplifying serial die-to-die physical layer implementations.

The group has reached its mission and is currently frozen.