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A lot of EDA and IP is increasingly based around standards. As a result, Cadence is actively participating in and contributing to standards bodies such as IEEE, JEDEC, Accellera, and Si2 to name a few. Here are the most recent standards that we have been heavily involved with:

• Accellera's Portable Stimulus Standard (PSS), which you can read about in my post A History of PSS.
• Cadence's Alessandra Nardi is the chair of the Accellera Functional Safety Working Group, which you can read about in my post Accellera Functional Safety.
• IEEE 1838 IEEE Standard for Test Access Architecture for Three-Dimensional Stacked Integrated Circuits, which you can read about in my post IEEE 1838: Taking Test into the Third Dimension.
• DDR5 memory interface standard, which you can read about in my post 2020 Is the Year of DDR5.
• Si2 Common Power Format (CPF) which was contributed to IEEE 1801.

Probably the oldest standard in the EDA industry that is still used is the GDS II layout standard. Through a series of acquisitions, this is actually owned by Cadence today, although it was originally developed by Calma back in the 1970s. You can read that story in my post Why Do Layout Designers Say "Stream Out"? 

There are a lot of bodies involved in standards, such as IEEE, Accellera, ISO, Si2 OA and CMC, JEDEC, and more, not to mention lots of protocols such as Ethernet and PCIe.

ETSI/3GPP/SA4

One particular standard body we have been working with recently is the SA4 working group of 3GPP group of ETSI, the European Telecommunications Standards Institute based in Sophia Antipolis in the South of France. As you might guess from the name, the 3GPP group was originally formed to drive the cellular standards for 3G mobile. The name remains the same although the focus moved onto 4G, 5G, and now 6G. While 3GPP looks at all aspects of the evolving technology, in particular they focus on interoperability and every semiconductor company and telecommunications operator (company) is a member. The SA4 working group deals with the specifications for speech, audio, video, and multimedia codecs, in both circuit-switched and packet-switched environments.

Cadence has a series of Tensilica processor IP for audio that goes under the "HiFi" name. For example, see my posts "Alexa, What Is HiFi 5?" and HiFi DSPs - Not Just for Music Anymore. These processors are the biggest selling audio processors in the world, with over 125 licensees and over 1.5 billion cores shipping per year.

Under the hood, the HiFi processors are built on Tensilica's Xtensa platform, a scalable and extensible technology that has been extended to VLIW DSP architectures. Other DSPs targeting audio processing have similar architectures. One part of any mobile phone is the vocoder (short for voice encoder and decoder). This takes audio input from the microphone, compresses it, and encodes it into a bitstream. The original GSM (2G) vocoder encoded voice into 16Kb/s, and later a half-rate encoder took that down to 8Kb/s. At the other (receiving) mobile, the digital stream is decoded (turned back) into digital wave samples that are then fed to a D/A (digital to analog converter) and finally to a transducer (earpiece) to render the sound. The encoding algorithm has to be standard since generally the two phones at different ends of the call are manufactured by different companies and contain different chips.

The reference codecs standardized by 3GPP are used by different semiconductor companies to actually implement them on their proprietary processing cores. The 3GPP reference codecs leverage an underlying foundational set of processing functions called basic operators. These basic operators were originally standardized by ITU (International Telecommunications Union) and called G.191: Software tools for speech and audio coding standardization, which can be viewed at https://www.itu.int/rec/T-REC-G.191-201901-I. ITU-T G.191 has Annex A, which describes ITU-T software tool library (STL) that has basic operators used in speech reference codec software. A major update to ITU-T G.191 and the basic operators was made in 2009. Since then modern DSP architectures have become prevalent with newer features like wide accumulators, SIMD and VLIW. It was time to update the older basic operators. Cadence contacted 3GPP and ITU and with their support augmented the old operators with a new set that leverages SIMD, VLIW capabilities in addition to providing support for 64-bit accumulator, complex numbers, enhanced 32-bit operations and additional control code operators. Cadence worked with 3GPP SA4 members to standardize on this newer set of basic operators that are now called STL2019. The output of this effort is at https://www.3gpp.org/dynareport/26973.htm.  This documents the benefit of STL2019 and what changed from STL2009 ->STL2019.  

Cadence continued to work with 3GPP SA4 to update the reference codebase for EVS (Enhanced Voice Services) codec to leverage STL2019 basic operators. EVS is a new hybrid audio and speech codec used in mobile telephony that encodes and decodes both audio and speech signals at different bit rates. Previous codecs only handled speech signals. The newer reference code for EVS leveraging STL2019 is called Alternative EVS Reference codebase and is located at https://www.3gpp.org/dynareport/26452.htm

Cadence developed the instruction set architecture (ISA) for its Tensilica HiFi 3z DSP in parallel with the development of these updated basic operators and the alternative EVS codec, resulting in the HiFi 3z DSP featuring an extremely efficient pairing of hardware and software. As a result, the HiFi 3z DSP offers a 1.6X improvement in million cycles per second (MCPS) as compared to the HiFi 3 DSP running the original EVS codec in Super Wideband mode—enabling lower power and longer battery life.

We worked with 3GPP in convincing them to update the reference code and the basic operators. Over two years we worked with them and 15 different companies (Intel, Ericsson, Nokia, Fraunhoffer, Samsung, Qualcomm, and more). We worked with all of them on how the new basic operators would look like. We then convinced 3GPP on what the new set of operators should be. Then we went through another round of consensus building to update the reference code to leverage the new basic operators. After the reference codebase was updated, the important task of interoperability tests started. Several of the participating members of 3GPP SA4 ran and validated the interoperability tests in their own labs. Cadence worked with each and every one of them during the interoperability testing, updating the reference software as appropriate. Each and every semiconductor company would confirm in their labs, so we worked with them to make sure interoperability was correct.

This new reference codebase using the updated STL2019 basic operators became the Alternative EVS Codec (the name for the new reference code with the new basic operators). Mobile phones using modern DSP architectures based on VLIW such as HiFi3z DSP can provide significant power savings while running this updated EVS codebase. The benefit of this new modern architecture is that code can be run in a much more power-efficient way. After we did that, we went back to ITU and they also updated based on our contribution. STL 2018 is the name of the library. With 3GPP’s approval for the enhanced, updated STL2019 basic operators, we went to ITU and worked with them to update the G.191 specification; the updated version can be found on the ITU site at https://www.itu.int/rec/T-REC-G.191-201901-I . And ITU has now also posted this release at https://github.com/openitu/STL

Summary

Cadence started this work in 2016 and successfully concluded it in 2019. The updated basic operators can be found at 3GPP site at https://www.3gpp.org/dynareport/26973.htm. And at the ITU site at https://www.itu.int/rec/T-REC-G.191-201901-I . ITU has now also posted this release at https://github.com/openitu/STL

The updated reference codebase for Alternative EVS codec approved by 3GPP can be found at https://www.3gpp.org/dynareport/26452.htm

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