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MIPI’s RF Front-End Interface Spec Expands its 5G Purview

June 12, 2020
The latest version of the MIPI Alliance's widely deployed RFFE specification enables more rapid and dynamic configuration changes within and across RF front-end subsystems.

In the latest version of its RF Front-End Control Interface (MIPI RFFE) specification, the MIPI Alliance has expanded the spec’s applicability to 5G use cases that move beyond mobile applications and into the realms of automotive, industrial, and the Internet of Things (IoT). MIPI RFFE v3.0 is designed to deliver the tighter timing precision and reduced latencies that manufacturers need to satisfy the RF requirements of the 3GPP 5G standard.

MIPI RFFE simplifies the design, configuration, and integration of the increasingly complex RF front end—which encompasses the power amplifiers, antenna tuners, filters, low-noise amplifiers (LNAs), and switches—connecting with the modem baseband and/or RFIC transceiver. As the number of RF bands involved in both uplink and downlink communications has exploded in the rollout of 5G, the subcarrier spacing (SCS) windows among RF packets have narrowed. MIPI RFFE v3.0 addresses the decreased reconfiguration windows and lower-latency switching among various bands and band combinations demanded in the 3GPP 5G standard by delivering enhanced triggering features and functionality, which results in fast, agile, semi-automated and comprehensive control of individual RFFE subsystems.

MIPI RFFE v3.0 utilizes multiple, complementary triggers to synchronize and schedule changes in register settings, either within a slave device or across multiple devices:

  • Timed triggers—Allows for tighter, synchronized timing control of multiple carrier aggregation configurations
  • Mappable triggers—Enables groups of control functions to be remapped to other triggers quickly and easily
  • Extended triggers—Boosts the number of unique triggers available in the RF control system and accommodates increasingly complex radio architectures

With the enhanced triggering functions, MIPI RFFE v3.0 improves throughput efficiencies and reduces packet latency, while also improving the precision in trigger placement. For back-to-back triggering operations, for example, the specification delivers a 20X improvement in timing precision.

Because MIPI RFFE v3.0 is backward compatible with prior generations of the specification, original equipment manufacturers and device vendors can migrate to 5G systems more quickly and easily, without changes to the physical layer of the control interface. The RFFE specification was initially released in 2010 and has seen numerous revisions since that time. Each release has provided additional functionality for developers to aid in the demand for newer RF front-end features.

“With MIPI RFFE v3.0, the specification has been streamlined and optimized to deliver the specific capabilities required to thrive in today’s 5G rollout across the Frequency Range 1 (FR1) of traditional sub-6-GHz cellular bands,” said Jim Ross, MIPI RF Front-End Control Working Group Chair. “The working group is always looking to refine the specification to continue differentiating and benefitting our user community, and we welcome engagement in requirements gathering for Frequency Range 2 (FR2) and the ongoing evolution of the next-generation MIPI RFFE for the subsequent stages of 5G deployment.”

MIPI Alliance, www.mipi.org