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Open-SourceSDRonEmbeddedPlatforms

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1 GTRI

June 1, 2016

Dr. Rajib Bhattacharjea

Georgia Tech Research Institute

Information and Communications Lab

Atlanta, GA 30318, USA

Open-Source SDR on Embedded Platforms

2 GTRI

Part 1 Overview

• Prereqs

• Topics to be covered

• SDR background

• SDR uses and users

• SDR components

• Demo 1

3 GTRI

Prerequisites

• Radio/Comms Fundamentals

- Analog and Digital Modulation

- Mixers, filters, LNA, PA

• Circuit analysis concepts

- Transistors

- Filters

• Software concepts

- High level language source code

- Assembly language

• Digital and analog signal processing concepts

- Convolution

- FFT

- Dot products

4 GTRI

What We’re Going to Learn About(and play with)

5 GTRI

Single Board Computers!

http://hackerboards.com/ringing-in-2016-with-64-open-spec-hacker-friendly-sbcs/

6 GTRI

Embedded Computers from the Living Room!

7 GTRI

Signal Processing with Open Source Tools!

http://wiki.opendigitalradio.org/FM_RDS_Stereo_transmitter_using_gnuradio

8 GTRI

Software Defined Radio Hardware!

9 GTRI

What We’re Going to Learn About

• Overview of available open-source software and embedded hardware tools for SDR development

• Signal processing

• RF signals

• How to get started with SDR on popular embedded platforms

- ARM or x86 embedded CPU

- Linux

• Commercial SDR hardware

• Optimized signal processing capabilities available on embedded platforms

10 GTRI

What We’re Not Going to Learn About

• OpenEmbedded, yocto, poky, bitbake…although those would help you with devices that don’t have packages in the distros, or for developing reproducible builds for distribution.

• Embedded CPU Hardware without available Linux kernel

• IBM Power ISA, µC(Linux), MIPS, SPARC, etc.

- Although the open source SDR ecosystem could be made to run on these kinds of platforms with various degrees of effort

- MIPS is especially low hanging fruit and much of this talk applies to those devices too

- Dedicated DSP chips

• “IoT” but only because we’re not talking directly about what data goes over the radio links we’re talking about. If it was some kind of sensor data, this would be an IoT talk.

• OSSIE (is it dead?)

11 GTRI

Background(who, what, when, where, why, how?)

12 GTRI

What is a Software-Defined Radio?

• A communication system where the capabilities are largely determined by the software running on the system instead of by the radio hardware.

• Consists of radio hardware and something to do the signal processing.

• The term “SDR” can mean the whole system, or just the radio hardware.

• Let’s consider a series of examples

13 GTRI

Conventional Radio Example: Super Regenerative FM Receiver

Design from: http://electronics-diy.com/simple-fm-radio.php

14 GTRI

Conventional Radio Example: Super Regenerative FM Receiver

• It’s purpose built for a specific task

• Designed to tune over 88 MHz – 108 MHz

• It isn’t easily reconfigurable and can perform no other task

- The hardware defines the functionality

- Many functional stages are collapsed into one; the one JFET is the:

• Oscillator

• Mixer

• Amplifier

• Filter

• Uses VERY few components, only enough to achieve the function it is designed for

15 GTRI

Conventional Radio Example: Superheterodyne FM Receiver

16 GTRI

Conventional Radio Example: Superheterodyne FM Receiver

Superheterodyne receiver schematic by Appaloosa released under CC-BY-SA 3.0 license.

https://commons.wikimedia.org/wiki/File:Tuner1.svg

17 GTRI

Conventional Radio Example: Superheterodyne FM Receiver

18 GTRI

Conventional Radio Example: Superheterodyne FM Receiver

Design from:

http://www.daenotes.com/electronics/communication-system/superheterodyne-fm-receiver

19 GTRI

Conventional Radio Example: Superheterodyne FM Receiver

Design from:

http://www.radio-electronics.com/info/rf-technology-design/fm-reception/foster-seeley-fm-detector-discriminator.php

20 GTRI

Conventional Radio Example: Superheterodyne FM Receiver

• It’s purpose-built for a specific task

• Designed to tune over 88 MHz – 108 MHz

• Design is more modular than the super regenerative design

- Amplification, frequency synthesis, frequency mixing, and a multistage demodulator

• Hardware defines the functionality

- Could change out the limiter and discriminator for a simple envelope detector and get an AM radio receiver

- Or a PLL and detect FSK

• Design is more complicated and uses about 7 times the number of overall components and 5 times the number of transistors

21 GTRI

Software Defined Radio: Superheterodyne w/ an ADC

22 GTRI

Software Defined Radio: Superheterodyne w/ an ADC

• Not purpose-built for a specific task!

• Tuning range can be large

• Signal processing is not done by a circuit designed for demodulation or discrimination of a specific type of waveform

• Software signal processing defines the functionality

- Hardware determines characteristics (tuning range, max instantaneous bandwidth, noise performance)

23 GTRI

Who Uses SDR and Why?

• Engineers in R&D

• Academics

• US Military- JTRS

- SCA

• US Intelligence Community

• Amateur radio enthusiasts (hams)

• Others

• Enables cutting edge research

• Speeds prototyping of new radio designs and signal processing algorithms

• Allows one radio to support different waveforms

• Permits radio designs to be upgraded without buying new hardware

• Facilitates detailed offline signal analysis

24 GTRI

Who uses SDR and Why? Video

• https://youtu.be/Lv-vkBNzZwE

25 GTRI

SDR Users / Developers in the DoD and IC

• The Army, Navy, Air Force, and Marine Corps

• “No Such Agency” in Fort Meade, MD- https://www.google.com/#q=nsa+redhawk

• Defense Contractors- Harris

http://rf.harris.com/media/RF-7800V-HH_Enlarged_26-12108.jpg

26 GTRI

Components of an SDR

• Analog front end

- Quadrature demodulator

- Wide or narrow tuning range

- Wide or narrow bandwidths

- RX Only, TX/RX half duplex, TX/RX full duplex, TX/RX MIMO configurations typical

• ADC

- Direct sampling ADC is a possibility, limits “tuning” range to (0,fs/2)

• Baseband processor w/ high speed interface

- FPGA

- CPU

- µC

• Signal processing software

27 GTRI

Components of an SDR: Front-end

28 GTRI

Components of an SDR: Baseband Processor

• Embedded device with a CPU or µC

• FPGA

29 GTRI

Demo 1 - CPU Frequency Demodulation

30 GTRI

Questions?

31 GTRI

Part 2 Overview

• Embedded platforms

• Consumer electronics embedded

• Capabilities

• Types

• Will it SDR? Demos 2 – 4

• Embedded ARM landscape

• SDR hardware options

32 GTRI

Embedded Processors(low power brains)

33 GTRI

Ubiquity of Embedded Platforms

• Embedded processors or µCs are in

- Car

- Television

- Speakers

- Sound system

- Wifi router

- GPS receiver

- Cable modem

- Camera

- Vacuum cleaner

- Refrigerator

- Watch

- Calculator, etc.

34 GTRI

Consumer Electronics Embedded Platforms

• Largest consumer electronics companies all sell embedded devices

- Connected TV devices

- Tablets - more than 250 million projected to sell globally in 2016[1]

- Smartphones – 1.4 billion units sold in 2015[2]

• Android and iOS devices drive this market

- Google

- Apple

- Samsung

- Amazon

[1] http://www.gartner.com/newsroom/id/2954317

[2] http://www.statista.com/topics/840/smartphones/

35 GTRI

Consumer Electronics Embedded Platforms

• These embedded CPUS go by the name “applications processors”

• Hardware manufacturers amortize investment into a technology; technology trickles laterally into the maker/hacker, educational, and industrial, and commercial communities

- Broadcom markets the BCM2820 as “optimized for high volume markets including mobile phones, mobile TVs, and portable audio/video/game devices”[1]

- Sells the almost identical BCM2835 as a learning platform to the Pi Foundation

- R&D companies ship Raspberry Pi’s to their customers in other products

• This is the class of embedded hardware we are talking about today

[1] https://www.broadcom.com/press/release.php?id=929312

36 GTRI

What Drives the Capabilities?

• Often, the killer app: streaming, decoding, and playback of media

- Special CPU instructions

- Media processor / GPU hardware

- Some of this capability might help in radio signal processing, more on this later

• This talk focuses exclusively on ARM and Intel

- Linux runs effortlessly, entire open-source ecosystem is available

- Can be extended to anything that runs a full, modern Linux kernel (MIPS24K in particular)

37 GTRI

Types of Consumer Electronics Embedded Platforms

38 GTRI

Set Top Boxes

• Class of devices used for consumption of media on TV screens

• Options:

- Roku devices

- Apple TV

- Amazon Fire TV

- WDTV

- NVIDIA Shield

- Many, many lesser known brands (check online retailers for “Android TV” or “set top box”)

39 GTRI

Set Top Boxes: Will it SDR?

http://www.cnx-software.com/2015/12/06/how-to-run-headless-linux-on-amlogic-s905-devices-such-as-mini-mx-or-k1-plus/

Yes it will!

40 GTRI

Stick Computers

• New class of small form-factor computers for vending signs, kiosks, TV streaming, etc.

• Options:- Intel Compute Stick

- Amazon Fire Stick

- Lenovo IdeaCentre

- Asus Chromebit

- Azulle Quantum Access

- MeeGoPad devices

- And others…

41 GTRI

Stick Computers: Will it SDR?

• Demo 2: Dongles on dongles

• Yes it will!

42 GTRI

Mini PCs

• Like a stick computer but slightly larger and the HDMI port goes the other way

• Generally more ports and/or storage

• Options:- Kangaroo MD2B

- Vensmile iPC002

- Compulab MintBox Mini

43 GTRI

Mini PCs: Will it SDR?

• Demo 3: Vensmile Mini PC SDR

• Yes it will!

44 GTRI

Single Board Computers (SBCs)

• Like a mini PC without the case

• Options:- Raspberry Pi

- BeagelBone Black

- Banana Pi

- Banana Pro M2

- Lemaker Guitar

- Adapteva Parallella 16

- CubieBoard4 CC-A80

- DragonBoard 410c

- Odroid XU4

- Odroid C1+

- MinnowBoard Tubot

- Intel Edison

- Nvidia Jetson TK1

- Nvidia Jetson TX1

- And others…

45 GTRI

Single Board Computers

http://hackerboards.com/ringing-in-2016-with-64-open-spec-hacker-friendly-sbcs/

46 GTRI

Single Board Computers: Will it SDR?

• Demo 4 – single board computer SDRs

- Raspberry Pi 2

- BeagleBone Black

- LeMaker Guitar

- NVIDIA Jetson TK1

- ODROID XU4+

- ODROID C1+

• Yes it will!

47 GTRI

Plug Computers

• A computer with AC mains prongs hanging off the case

- Like a wall-wart, but a computer

• The guts are similar ARM processors

• A few vendors on the market sell this form-factor

48 GTRI

Plug Computers

49 GTRI

Plug Computers: Will it SDR?

50 GTRI

Embedded ARM Landscape

Manufacturer Brand Name End Devices

Texas Instruments OMAP Kindle Fire HD, Droid X, Droid 2

Broadcom Raspberry Pi

Allwinner Tablets

Rockchip ASUS Chromebook, TV Boxes/Sticks

MediaTek Tablets, Phones

Qualcomm Snapdragon Google Nexus One, HTC Incredible

Marvell ARMADA Panasonic Toughpad A1, Google Chromecast

Amlogic TV Boxes

Samsung Exynos HP Chromebook, Samsung Galaxy S6

NVIDIA Tegra NVIDIA Shield

Apple AX iPhone, iPad, Apple TV, Apple Watch

Actions Semiconductor Tablets, TV Boxes

NXP i.MX, QorIQ Amazon Kindle

HiSilicon Huawei Devices

Atmel SMART SAMA5 Dev Boards

Renesas Samsung Galaxy Core LTE

51 GTRI

SDR Hardware

• Ettus USRP

• Great Scott Gadgets HackRF

• Nuand bladeRF

• LimeSDR

• Realtek RTL2832U-based devices

• Afedri SDR

• Airspy R820t

• RFSpace

• RedPitaya

• Nutaq PicoSDR, ZeptoSDR

• PicoZed SDR

• FunCube Dongle Pro+

• SDRPlay RSP

• And more...

52 GTRI

SDR Hardware: References

• https://en.wikipedia.org/wiki/List_of_software-defined_radios

• http://sdr-radio.com/Radios

• http://www.rtl-sdr.com/roundup-software-defined-radios/

• http://gnuradio.org/redmine/projects/gnuradio/wiki/Hardware

53 GTRI

Questions?

54 GTRI

Part 3 Overview

• Open-source SDR signal processing software

• Install guides – Demos 5 and 6

• Non-free tools

• Core SDR signal processing operations

• Speed and optimization

• Intro to CPU ISA extensions

55 GTRI

SDR Software Options

• GNU Radio

• Mathworks MATLAB*

• NI LabVIEW*

• REDHAWK

• Scilab

• Custom signal processing code (C++, Python, etc.)

* Not publicly available on ARM architecture, not free of cost

56 GTRI

Open Source SDR Software: Getting Started

• Get a Linux distro

- Download and “dd” an image file on to an SD card

- Or get it onto the on-board eMMC

• Keyboard, monitor, mouse, etc.

- Or setup networking for headless operation

• Install your SDR software

- More on this later

57 GTRI

GNU Radio: Getting Started

• Install - package manager- Debian derivative - install using apt

- Red Hat derivative – install using dnf(yum is deprecated)

- Others: zypper, pacman, urpmi, RTM for your distro

• Install – source- Install dependencies from package

manager if possible

- Then git clone, cmake, make, make install

- Cross compilation or other tricks might be necessary• Embedded systems are limited in

computational power, and GNURadiocompilation is CPU intensive

• RAM can be an issue

• eMMC flash storage can be an issue

• Colleague’s GNU Radio compile on a Raspberry Pi took a week

58 GTRI

GNU Radio Install

Demo 5

59 GTRI

REDHAWK

• Open source signal processing package largely developed for/by the US government

• Supported on RHEL or CentOS Linux distributions; developers implicitly assume x86

• Port of REDHAWK for Ubuntu exists

- Old version of RedHawk (1.8.4)

- Old version of Ubuntu (12.04)

• Developer community size is a bit of a mystery

- Fewer than 200 questions on the official Q&A site for redhawk software

- Zero questions on the official Q&A site for redhawk-related hardware problems.

• ARM ports will take some work

60 GTRI

REDHAWK

• Demo 6: REDHAWK on embedded ARM

61 GTRI

SciLab

• Some efforts exist to use a combination of SciLab and GNU Radio

• Not developed for SDR work, but for interfacing with data acquisition hardware

https://www.researchgate.net/publication/266009629_GNURadio_Scilab_Xcos_and_COMEDI_for_Data_Acquisition_and_Control_An_Open_Source_Alternative_to_LabVIEW

62 GTRI

Non-Free Tools (MATLAB and LabVIEW)

• Title of the tutorial contains “Open-Source SDR…”

• You can open source the code you write but development tools are not free (neither “freedom” nor “beer”)

• Mentioned here for completeness

63 GTRI

Custom Signal Processing / Vendor APIs

• Most SDR manufacturers have written C/C++ libraries interfacing to the hardware

• These can be variously used directly or through wrapper/binding layers to other languages

64 GTRI

Signal Processing on Embedded Platforms(make it go faster)

65 GTRI

Embedded Processing: Operations and Speed

SDR Operations

• Modulation

• Entropy and error coding

• Encryption

• Computationally heavy DSP operations- Convolutions

- FFTs

• Potentially high data rates

• The modern CPU is optimized for managing the flow of instructions, not quickly executing a small group of instructions

• CPU manufacturers see this gap, have created special CPU instructions for common DSP or multimedia computations

66 GTRI

Embedded Processing: Operations and Speed

Dot product

𝑥 𝑛 ∙ 𝑦 𝑛 =

𝑚=0

𝑀−1

𝑥 𝑚 𝑦[𝑚]

#define M (1L << 16)double dotProd_1(double *x, double *y){

double out = 0;int i;for (i = 0; i < M; i++){

out += x[i] * y[i];}return out;

}

67 GTRI

Embedded Processing: Operations and Speed

Convolution (FIR filter)

(𝑥 ∗ 𝑦) 𝑛 =

𝑚=0

𝑀−1

𝑥 𝑛 −𝑚 𝑦[𝑚]

#define M (1L << 4)#define L (1L << 4)void convolution_1(double *x, double *y, double *out){int n;for (n = 0; n < L + M - 1; n++){out[n] = 0;int m;for (m = 0; m < M; m++){

if(n-m < 0 || n-m > L-1)continue;

out[n] += x[n-m] * y[m];}

}}

68 GTRI

Embedded Processing: Operations and Speed

• Matrix multiplication

- Could be for adaptive zero-forcing equalizer

𝑋𝑌 𝑖𝑗 =

𝑚=0

𝑀−1

𝑋 𝑖,𝑚 𝑌[𝑚, 𝑗]

• Code omitted, but now three loops

- One over 𝑖, one over 𝑗, and one over 𝑚

- But the multiply and add up bit is the same!

69 GTRI

Embedded Processing: Operations and Speed

• Operation of multiplying elementwise between lists and summing is a very common operation.

- Previous examples (signal convolution, matrix multiplication)

- Vector projection 𝑥1𝑦1+𝑥2𝑦2+𝑥3𝑦3

𝑦12+𝑦22+𝑦32

- Polynomial evaluation 𝑎0 + 𝑎1𝑥 + 𝑎2𝑥2 + 𝑎3𝑥

3

• What if someone identified many of these common kernels of code and spent time optimizing them using CPU extensions for specific hardware?

- The bit that boils down to pure math and runs in the innermost loops

70 GTRI

Ways to Achieve Speed on Embedded CPU

Use the CPU extensions; how?

• Use compiler features directly

• ORC

• VOLK

• OpenCL

• Performance-tuned libraries

71 GTRI

CPU Extensions

• Additions to the instruction set for some specific application

• Drivers: media, graphics, security

• Speed-up computations or increase power efficiency

Applications

• Encoding or decoding modern video/audio standards - DCT in audio/video compression

• Rasterization, shading, ray tracing for gaming

• Hashing / encryption operations

72 GTRI

CPU Extensions

• Vectorized or vector or SIMD

• Maximal DSP performance out of an embedded processor

• Intel – MMX, SSE, SSE2, SSE3, SSSE3, SSE4, AVX, AVX2

• ARM – DSP extensions, SIMD, NEON

• Can be leveraged for embedded signal processing!

• Writing assembly can be problematic, not for everyone

• Not portable across architectures

73 GTRI

CPU Extensions: Intel PMADDWD

74 GTRI

CPU Extensions Example

outerloop:

pxor xmm0, xmm0 // initialize 4 accumulators (32Bit)

sub ebp, ebp // init Index in filter taps w/ zero

innerloop:

movups xmm1, qword ptr [esi+ebp] // ld 8 vec in 128Bit reg

pmaddwd xmm1, qword ptr [edi+ebp] // pairwise mult with TAPs

paddd xmm0, xmm1 // accum results in xmm0 (4x32 Bit)

add ebp, 2*8

cmp ebp, 2*64 // repeat for all 64 Taps

jnz innerloop

phaddd xmm0, xmm0

phaddd xmm0, xmm0 // accumulate four partial vals to one result

psrad xmm0, 15 // scale to 16 Bit

movd qword ptr [eax], xmm0 // store result (only 16 Bit relevant)

add esi, 2

add eax, 2 // increment pointer for input & output

sub ecx, 1 // repeat for all input samples

Questions:

• What does that do?

• Is that optimal in any sense?

• What extension set is it using?

• Will it run on an Atom Z3735F? On an ARMv7?

https://software.intel.com/en-us/articles/using-intel-streaming-simd-extensions-and-intel-integrated-performance-primitives-to-accelerate-algorithms

75 GTRI

Questions?

76 GTRI

Part 4 Overview

• CPU extensions

• GPGPU on embedded

• Using the FPGA

• Special coprocessors

• Conclusions and wrap-up

77 GTRI

Optimization Path 1: CPU

78 GTRI

How to Leverage CPU Extensions: Compiler

• Compiler intrinsics expose the CPU vector operations. Like writing assembly code in the middle of C++.

- Portability problem across CPU types

• Special data structures (vector types) + normal operations that the compiler can recognize and optimize

- Portability problem across compilers

• -O3

- It just works!...? No.

79 GTRI

How to Leverage CPU Extensions: Compiler

• Demo 7: C++ code with assembly breakdown

- Add two signals together sample by sample in a loop

• You have to coax the compiler into optimizing, then look at the performance yourself and determine if the assembly matches your expectations

• Even then it might be suboptimal and more performance tuning can be required

http://locklessinc.com/articles/vectorize/

80 GTRI

How to Leverage CPU Extensions: ORC

• ORC, Optimized inner loop Runtime Compiler

• Generic SIMD language that gets compiled to optimized instructions for the target processor

• Inner loop code is optimized using vector instructions, across architectures

• User drops in optimized implementations

- Without having to coax the compiler into the optimization

- Without hand writing the machine specific assembly (but ORC is assembly-like)

• Supports ARM NEON, Intel MMX/SSE, and others (PowerPC Altivec)

• Different modes

- JIT compilation mode

- Hardware specific machine code that gets baked into the executable.

81 GTRI

How to Leverage CPU Extensions: VOLK

• Vector Optimized Library of Kernels

• Signal processing functions that vectorize well across architectures

• Protokernel – tuned implementation that runs on specific hardware

• Different protokernels are profiled and what’s fastest is stored

• Kernel -> profiler data -> dispatch

- Empirically fastest implementation

- Similar to the FFTW library (“wisdom”)

• ARM NEON and Intel SSE/AVX

• If no SIMD acceleration, plain C implementation is used

http://libvolk.org/

Image © Marcus Müller

82 GTRI

How to Leverage CPU Extensions: OpenCL

• Open Computing Language

• C-based language designed for optimizing math heavy operations

• Some constructs are designed to map to SIMD structures on particular hardware

- “float4” is a type with four single precision floating point numbers

- Can map directly to Intel SSE XMM0-XMM7

• OpenCL code can be compiled for

- CPU: uses SIMD / other extensions

- GPU: uses massively parallel shader architecture

- Special OpenCL coprocessors: Intel Xeon Phi, Adapteva Epiphany

83 GTRI

How to Leverage CPU Extensions: OpenCL

Hardware must have OpenCL implementation available

• Intel ships OpenCL implementation for their CPUs

• Official ARM CPU OpenCL using NEON was announced but unavailable?

• ARM Mali GPU design does have an OpenCL implementation, more on this later

• POCL

- Portable Compute Language

- OpenCL implementation for ARMv7, x86, MIPS32

84 GTRI

How to Leverage CPU Extensions: OpenCL

• Demo 8: OpenCL Acceleration demo with gr-fosphor on Vensmile iPC002 (Intel Atom)

• Formerly had to do this on some distros:

- https://bitbucket.org/snippets/rajb245/epGzn

• But latest Intel OpenCL Runtime 16.1 supports RHEL, SLES, and Ubuntu

- https://software.intel.com/en-us/articles/opencl-drivers

85 GTRI

How to Leverage CPU Extensions: Performance Tuned Libraries

Background – BLAS

• Basic Linear Algebra Subprograms

• API definition of common numerical operations

• Level 1: Scalar/vector and vector/vector operations

- Rotating 2-vectors, dot products, scalar times vector, vector norms

• Level 2: Matrix/vector operations

- Matrix/vector multiplication, triangular matrix system solver, vector outer product

• Level 3: Matrix/matrix operations

- Matrix multiplication

- Sums of products of matrices

• Do they map directly to signal processing?

86 GTRI

How to Leverage CPU Extensions: Performance-Tuned Libraries

• CPU vendors make performance-tuned BLAS (and the related LAPACK) implementations- AMD ACML – open sourced, BLIS

is what we want for the CPU, runs

on ARM and x86, very portable

- Intel MKL – Intel and AMD x86,

closed source

• ATLAS project automatically tunes itself on the target hardware, works on ARM

• OpenBLAS has comprehensive architecture support https://software.intel.com/en-us/intel-mkl

87 GTRI

How to Leverage CPU Extensions: Performance-Tuned Libraries

Open questions

• Integration of high-performance BLAS into GNU Radio? REDHAWK?

88 GTRI

Optimization Path 2: Embedded GPU

89 GTRI

Embedded GPU Landscape

• Consumer electronics embedded processors often have specialized multimedia processing hardware / GPU (recall the killer app)

• End device list not exhaustive

IP Holder Brand Name Licensees / Manufacturers End Devices

Broadcom VideoCore Broadcom Raspberry Pi, Samsung Galaxy (various)

ARM Holdings Mali Allwinner, Amlogic, MediaTek,Rockchip, Samsung

Samsung Gear/Galaxy/Chromebook (various), Google Nexus 10, ODROID (various)

NVIDIA Tegra GPU NVIDIA NVIDIA Shield, Acer Chromebook,Google Pixel C, HTC Nexus 9

Intel HD Graphics, GMA,Iris, Iris Pro

Intel Dell Pro 11 2in1, Lenovo ThinkPad (various), Dell Venue 11 Pro

Qualcomm Adreno Qualcomm Samsung Galaxy (various),Sony Xperia X, HTC 10

Imagination Technologies

PowerVR Ti, Apple, Intel, Broadcom, Allwinner, Samsung, Rockchip

iPhone (various), iPad (various), Apple Watch, PS Vita, Asus Zenfone 4, ODROID-XU

VivanteCorporation

(None) Marvell, Freescale, IngenicSemiconductor, Rockchip

Samsung Galaxy Tab 4, Chuwi V90, Hummingboard (various)

90 GTRI

GPU Processing on Embedded

• Mali OpenCL is the only easy option right now

- Signal processing with AMD clMath?

- Integration into GNU Radio or REDHAWK?

• PowerVR has beta access to OpenCL for developers

• NVIDIA has CUDA

- Library of functions that turn into highly parallelized code that runs on the GPU

- Specific to one vendor

• Some work has been done on Broadcom VideoCore

- Assemblers for the VideoCore, including one where you write assembly in python (PyVideoCore)

- PyVideoCore has a single example of a single BLAS/LAPACK function

91 GTRI

GPU Processing on Embedded

• Demo 9: Mali GPU w/ OpenCL gr-fosphor

92 GTRI

Optimization Path 3: FPGA

93 GTRI

FPGA Processing

• Field-programmable gate array

- Can be configured to be an arbitrary digital logic circuit (within a size constraint)

• Many of the SDR hardware platforms have an on-board FPGA

- Handles interpolation, decimation, fine frequency tuning, digital I/O buses (host and RF front-end)

- HackRF*, Ettus B and N series, bladeRF, and others

• Some embedded processors have an on-die FPGA†

- Xilinx Zynq

- Altera SoC

*Actually a CPLD, but the difference is in implementation not functionality

†Intel Xeon+FPGA is hardly embedded and is vaporware so far

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FPGA Processing

• Xilinx Zynq powers three popular SDR platforms- Ettus E310

- Red Pitaya

- PicoZed SDR

• Do most of the signal processing on the FPGA

• Use the ARM for what’s left

• Development Tools- LabVIEW FPGA Module*

- MATLAB HDL Coder*

- RFNoC

http://www.xilinx.com/products/boards-and-kits/1-askjht.html

https://www.ettus.com/product/details/E310-KIT

*Not free, no public ARM release

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FPGA Processing

• Demo 9: RFNoC fosphor on the X310

- (Martin Braun’s demo is much better, so we’ll skip this)

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Optimization Path 4: Other Coprocessors

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Special Coprocessors

• Xeon Phi- Not embedded yet; power draw is

same as thirty SBCs

• Adapteva Epiphany Coprocessor- Has not really caught-on

- Used in one design, the Adapteva

Parallella-16 SBC

*http://www.intel.com/content/www/us/en/architecture-and-technology/many-integrated-core/intel-many-integrated-core-architecture.html

*

http://www.adapteva.com/epiphanyiii/

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Conclusions and Summary(what did we learn)

99 GTRI

Conclusions and Summary

• Embedded SDR runs the gamut of price and performance

- Pi Zero + RTL2832U device

- ODroid + Hack RF

- Ettus E310 or PicoZed SDR

- NVIDIA Tegra TX1 + Ettus X310

• GNU Radio is the dominant open-source SDR package that is popular for researchers and hobbyists

- Others exist but there’s no annual “REDHAWK con”, i.e., the user community and support seems to be best for GNU Radio

• Using available, COTS, embedded hardware and open-source software, any practical radio technology can be implemented

- Even experimental technology can be realized

- Massive MIMO

- Spectrum sensing / cognitive radio

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Conclusions and Summary

• You can’t pick up an embedded device and get optimal signal processing performance

- Software work to be done to leverage the processing power of the GPUs and SIMD technologies

- Should the VOLK project support GPU accelerated implementations?

- Should everyone use OpenCL?

- Or should there be accelerated BLAS/LAPACK, and other code can call those functions?

101 GTRI

Conclusions and Summary

• It’s an exciting time in embedded SDR!

• The unprecedented popularity of mobile, wireless, and TV markets has effectively subsidized the SBC and embedded computer market.

• You can realistically learn SDR and signal processing with practical, hands-on experience for the price of a drink at a nice restaurant.

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Acknowledgements

• Ben Riley of GTRI for funding IRAD

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Thank You

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Copyright Notice

• Copyright 2016, Georgia Tech Applied Research Corporation

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- Where possible, attribution has been given to the original rights holders.

- Use of these portions has been for the purposes of comment, teaching, scholarship, and research; as such, the authors of this work assert that this usage constitutes a fair use of the copyrighted material.

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- (1)the purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit educational purposes;

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