© Tata Consultancy Services ltd. April 15, 2023 1

Challenges in Embedded Systems Development – Wireless Radio

Perspective

Arpan Pal

Convergence Practice,Tata Consultancy Services,

Kolkata, Indiaemail : arpan.pal@tcs.com

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Wireless Radio Technologies

Media Source Head-end / Base station CPE-device

InternetLAN / PAN

Satellite

Satellite

Residential Gateway

LA

N /

PA

N

WAN

MAN

UWBBluetooth

Zigbee

PAN

WiMAX802.16d / eBroadband

DVB-C DVB-T

Wi-Fi802.11 a/b/g

NFCRFID

LANMAN

WCDMA/HSDPAHSUPA/GPRS/EDGE EVDO

DVB-H

DVB-SGMR/GMPRS

WANSatellite

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Embedded Devices in Wireless Radio

CPE DevicesBase-station

equipmentTest

equipment

•Low Cost•Small Size•Low Power•Field-Upgradeable•User-friendly•Feature-rich•Multimedia-enabled

•High Performance•Low Power-Performance Ratio•Upgradeable to newer standards•Interface-friendly to allow multi-vendor setup

•High Performance•Reasonable Size Limitation•Upgradeable to newer

standards•Friendly User Interface to

run tests•Complete Test Coverage

Wireless RadioDevices

(PHY and MAC)

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Engineering Challenges

Needs to have robust field-upgradation feature Needs to have comprehensive test-coverage, preferably automated Needs to cater for delayed availability of Hardware Needs to have distinguishing and differentiated features

Yet has to be of lower cost meaning that only low power CPUs and less memory available for applications.

Yet has to be of lower power meaning that more and more features has to be implemented in hardware (at least for portable devices)

Yet needs to meet real-time constraints Yet has to be developed under stringent development schedule Yet needs to follow laws of Physics

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Technology Challenges

Standard-driven – hence development has to start before standard is out and needs to adapt to standard modifications

The chosen implementation platform needs to have flexibility for standard adaptation

Technology life is usually small – need to extend this through partners and industry bodies

Yet has to be of lower cost Yet has to be of lower power (at least for portable devices) Yet has to be developed under stringent development schedule

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Portable Devices Base Stationequipment

Testequipment

SOC(ASIC / ASSP)

ProgrammableDSP

Microcontroller

FPGA / EPLD

ReconfigurableArchitecture

Programmability

Pow

er & S

pace O

ptimization

Hardware Platforms for Wireless Radio

Software-defined Radio (SDR)

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SDR Principles

Drivers

An ever expanding set of ‘contexts’

Adaptive Embedded

Telecom

•Active Networks•BS Adaptivity

•Handheld •BS Frontend

•Software Defined Radio

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SDR Features

SDR technologies provide software control of a variety of modulation, interference management and capacity enhancement techniques over a broad frequency spectrum (wide and narrow band), while ensuring secure communications management.

Standard architecture for a wide range of communications products Non-restrictive wireless roaming Flexibility and adaptability Potential for significant life-cycle cost reductions Over the air upgrades

• Ease of design - Common RF front-end with different signal processing software • Multimode - Simply loading appropriate software into the memory • Use of advanced signal processing techniques - Implementation of new receiver

structures and signal processing techniques such as adaptive antennas, interference rejection, and strong encryption

• Fewer discrete components - Decrease the size/cost and increase maintainability• Flexibility to incorporate additional functionality—Better features and diagnostic

through software upgrades

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Hardware-Software Partitioning

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Example Case Studies- Challenges and Solutions

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Physical Layer for 3G Protocol Conformance Tester

Scope• Design• Implementation of signal processing blocks• Unit testing by Automated Test Framework• Addition of L1 functionalities• Development of control interface• System integration and validation

Environment• Target Hardware:

- TI TMS320C6202 Octal DSP Board• Software and Tools:

- MATLAB Toolbox- TI CCS

• Languages- MATLAB- C

Challenges• Complex and Computationally-intensive Signal Processing Functions (Spreading, Viterbi, Turbo)

SolutionDSP Optimization

• High Data Rate – hence needs to be of low latencySolution

Complex functions in FPGA• Complex L1 Control Functions, high data-rate between processors

SolutionCareful functionality based partition for master and slave DSPs to reduce Inter-processor communication bandwidth

• Rigorous unit testing and system testing ensuring complete coverage

SolutionAutomated Test Framework

StandardsHSDPA (UMTS Rel. 5), 1x-EVDO (cdma2000 Rev. A), HSUPA (UMTS Rel. 6)

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Test vector generation

Standards (HSDPA, HSUPA, 1xEVDO …)

Unit test plan

Input test vectors

Test Harness

Reference algorithm implementation

Target DSP implementation

Reference Output Actual Output

+

-

Test report(Pass / Fail/ Diagnostics)

Configuration setupTest case setupTest vector formatReference and target configurationError Criterion

MAD / SAD / Bit true /Symbol TrueGENERALIZED TEST PLATFORM

Automated DSP Test Framework

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Automated DSP Test Framework

Salient Features• Generates test vectors combinatorial to input parameters

• Supports both little-endian and big-endian architectures

• Supports both signed and unsigned data types.

• Concept of ‘Tying-up’ parameters has been introduced.

• Various bit-streams All 0's, All 1's Alternate 1's and 0's starting with 1 or 0 Random 1's and 0's - 1's and 0's with

equal/different probability

• Variable data width

• Totally automated for running all test cases

• Automatic comparison of results

• Automatic measurement of execution time

• Can be tested for bit-exactness as well as specified allowable difference

Objectives• Build an automated test harness for

regression testing of signal processing function implementation

• Minimize testing effort and thereby cost

• Minimize manual interaction

• Design should be adoptable to various platforms

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IEEE 802.16 WiMAX MAC

Scope

• Design, Development and Testing of SS & BS MAC

• First Phase Development on Simulated PHY

• Porting and Integration with hardware PHY and RF.

• Addition of 802.16h

• Development towards 802.16e

Environment• Target Hardware:

- PowerPC based Board• Software and Tools:

-Low foot-print Linux Kernel-GNU Toolchain

• Languages- C/C++- TTCN

Challenges

• Complex State-machine with requirement for interfacing to multiple PHY chips and upper layers

SolutionUse of Generic MAC framework

• Computationally-intense blocks like encryption and need of extremely fast response time for certain messages

SolutionRequires careful Hardware-Software partitioning and use of Lower-MAC

• Designing scheduling algorithms to guarantee QoSSolution

Use of MAC Simulator Framework

• Thorough Testing and Standard ComplianceSolution

Use of MAC Testing Framework

• Cognitive Radio Concepts (802.16h, 802.22)Solution

Participation in Standard Bodies

StandardsIEEE 802.16-2000 (WiMAX Fixed), IEEE 802.16e (WiMAX Mobile)

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Wireless MAC FrameworkSimulator Framework

• PHY abstraction for performance evaluation• Simulator level, node level and protocol level control• Performance Visualization – throughput and delay

Development Framework• Generic Framework for Wireless MAC engines• Adaptable to most of Wireless MACs• Reduces MAC development time without compromising on performance

Test Framework• Standard based test definition• Automated Execution• Unit and Module level Testing• Automated Report Generation

• Network Simulator (version 2) based• Tuned for Wireless Networks• Topology, simulation duration, mobility, flow definitions @ simulator level• Protocol stack definition @ node level • Parameter definition @ protocol level• Currently done for IEEE 802.15.3 UWB MAC

• Core MAC, PHY-SAP and MAC-SAP separated out• Thin OSAL• Independent library module for utility functions• Currently being done for WiMAX 802.16-2004

• Test suite Adaptation Layer• Test Execution Adaptation Layer• Test Management Layer• TTCN-3 based scripting for test suite definition• Currently being done for WiMAX 802.16-2004

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Generic MAC Development Framework

Physical Layer

Core MAC

PHY-SAP Interface

Framework

Library OSAL

Device Driver

MAC-SAP Interface

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Thank You