Since their release, the Ensigma Series4 family of Radio Processing Units (RPUs) has been the powerhouse for high-performance connectivity standards such as 802.11ac 2×2 and 802.11n 4×4 as well as many TV and radio broadcast standards supported by Imagination. Multiple customers have licensed these RPUs to integrate more (or all) high-performance connectivity on-chip; examples include S2-Tek, Toshiba, Elvees, Rockchip, and others.

However, the fast-growing demand for higher data rates driven by bandwidth-hungry applications such as video streaming together with the adoption of more advanced standards and configurations (e.g. 802.11ac 4×4, 8×8 or 802.11ax) requires radio processors with higher scalability, programmability and debug capabilities.

To address these requirements, we are introducing a new generation of multi-standard radio processors called the Ensigma Series5 family.

This advanced family of RPUs is designed to support the high-performance requirements of the wireless applications mentioned above and also maintain backward-compatibility to the Series4 generation, providing a fast upgrade path for current Explorer customers. You can find a block diagram of a fully-featured Series5 RPU below:

Ensigma Series5 RPU - Ensigma Explorer Wi-Fi Bluetooth LoWPAN FM radioThe architecture of the Ensigma Series5 RPU

Alongside several updates and improvements to the existing hardware blocks, Ensigma Series5 RPUs feature some new elements too; for example, Series5 introduces a MIPS-based Embedded Control Unit (ECU) alongside the Modulation and Coding Processor (MCP).

Read on for a more detailed description of the hardware module and their capabilities.

The Embedded Control Unit

The optimized Series5 architecture allows multiple slices of the ECU and CPU to function simultaneously, facilitating easy scalability to higher bandwidths and data rates. Both the ECU and CPU are ideally suited to run control and scalar processing tasks, therefore offloading the MCP and allowing it to focus on core vector and DSP-based operations. In addition, the CPU is used to run the MAC layer functionality in typical Wi-Fi applications.

Advanced MIPS built-in features including multiple registers sets, a co-processor interface, faster interrupts, and more – thus enabling the companion ECU to function as a Layer 1 controller for the MCP.

Both the ECU and CPU can easily be programmed using industry-standard, high-level languages (such as C), giving the Series5 RPU architecture the flexibility to support and adapt to any next-generation connectivity standard.

The Modulating and Coding Processor

As we’ve mentioned, at the heart of the Series5 RPU is the MCP which focuses on DSP tasks. The MCP is a 4, 8, 16 or 32-bit wide SIMD engine that handles all the vector processing. The number of MCP slices can be increased based on throughput and performance requirements. The Series5 RPU comes with a number of built-in library functions for the MCP which significantly reduces the assembly code needed. In addition, the MCP toolkit generates stub functions which can be called easily from the ECU – again simplifying programming.

All the above features are combined with an elaborate set of hardware accelerators which offload the MCP of standardized tasks such as the LDPC (low-density parity coding) and Viterbi decoding. The ability to blend a programmable engine with fixed function hardware provides for future proofing of upcoming standards while at the same time balancing power and area requirements.

Similar to the previous generation RPUs, the Series5 family provides standard back-end interfaces to the system memory and host bus. This makes it easy for customers to upgrade to the new architecture. At the front end, Series5 RPUs can easily work with the standard digital I/Q interfaces.

Finally, the Series5 RPUs provide superior logging capabilities and tools. The logging capability is very useful when debugging complex real-time scenarios and provides the ability to build a type of logic analyzer trace of all events within the RPU. There are many tools available such as the RPU simulator, emulator, toolkit, and Codescape SDK that significantly ease development efforts for our customers and partners.

Conclusion

The new Ensigma Series5 RPUs are part of the larger Explorer family designed to address the needs of high-speed connectivity, TV demodulation and radio demodulation standards shown in the table below (802.11ac, 802.11ah, 802.11ax etc.). Meanwhile, the Ensigma Whisper series of RPUs continues to address low-power connectivity standards (Bluetooth Smart, 6LoWPAN etc.)

Ensigma RPU: 802.11ac 802.11ax 802.11ah 802.15.4 Bluetooth

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About the author: Narayanan Raman

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