RF Design and Simulation of Wireless Systems - CEI-Europe
Course #15

RF Design and Simulation of Wireless Systems

June 4 - 8, 2018 . Dresden, Germany

We recommend you to submit your preliminary or firm registration at least 4 weeks before course start to ensure a seat on the course.

TECHNOLOGY FOCUS

Radio systems and the signals within them are becoming increasingly complex, with both digital and analog functions often implemented using CMOS and other semiconductor technologies. Understanding such systems at the block diagram level is helpful, and becomes straight forward using powerful system simulation tools. Deeper insight is possible when the circuits are also better understood and characterised.

RF circuits are typically designed to meet power, efficiency, gain, linearity and noise specifications when driven by single or two-tone excitations; whereas the radio system is driven by much more complex signals and must be designed to meet specifications like bit error rate, dynamic range, and minimum detectable signal in the presence of interferers. With a pair of radios, the communications link itself must achieve a given bit rate, consume minimal bandwidth, not interfere with other systems, and cover a certain distance.

Through understanding the interactions between circuits, and through careful simulation of both circuits and systems, and modelling the link, all levels of specifications can be reconciled.

COURSE CONTENT 
This 5-day course has just been updated with the latest example of a commercial microwave digital radio link, including the link budget, and will show how some of the most recent wireless systems technology is put into practice.

At the communications link level, we will see how link distance, antenna gain, and signal thresholds can be traded off against each other; and how channel bandwidth improves the link capacity in spite of elevating the receiver noise floor!


We will focus on examining tradeoffs in the design of wireless systems themselves, and show how to seamlessly move between both the circuit and system level in radio transceivers and other RF systems. We do this by looking at typical radio architectures, exploring the design tradeoffs, and simulating at both the circuit and system level. The course treats digitally coded signals in RF and IF components, and explores the compromises that are inherent in the design of a radio transceiver. For example, a receiver needs to minimize interference from nearby unwanted stronger signals and allow detection of a desired signal in noise. For the transmitter, avoiding corruption of other signals sharing nearby spectrum is critical. Achieving both together is not so simple!

In wireless LAN for instance, we will see how tradeoffs in signal modulation and multiplexing (i.e. OFDM) made to improve performance in some parts of the system, such as multipath reception, have placed tight constraints on other parts of the system, such as the linearity and efficiency of the transmitter. We will interactively simulate a double super-heterodyne, dual-band radio receiver, a direct conversion receiver, and an I-Q modulator and transmitter, as well as various components that make up these systems. This provides the opportunity to explore 'what if?' scenarios. We will also get "inside" the circuits themselves for a greater understanding of how each component works, and contributes to overall system performance.

To benefit most, bring your own laptop computer and, prior to attending, obtain a free trial license of the Visual Systems Simulator (VSS) from AWR at www.awrcorp.com.


On completion of the course, you will be:

  • Familiar with the physical layer specifications of an RF wireless system, and understand how the key system parameters relate to RF hardware and the communications link itself
  • Able to understand and write critical RF specifications for wireless communications systems
  • Able to simulate various types of RF and IF systems and component interactions
  • Comfortable with reading integrated circuit data sheets for wireless systems, their architecture, and specifications
  • Able to understand the compromises in choosing architectures and circuits to meet given system requirements
  • Fully conversant with how super-heterodyne architectures work, how they are implemented, and the challenges to watch for
  • Familiar with microwave and RF subsystems such as amplifiers, mixers, and oscillators

Monday
Radio Systems and Digital Communications
We start by reviewing digital wireless communications and a variety of modulation formats, and the tradeoffs between capacity, bandwidth, signal power, and noise. We look at the upconversion and downconversion processes in typical receiver and transmitter architectures, and the effects of filtering.

  • Revision of Communication and Information Theory Principles
  • Coding and Modulation Formats
  • Baseband Filtering and Impact on Signal Constellation
  • Typical Receiver System Architectures - Direct Conversion, Superheterodyne, Dual Conversion Superheterodyne

Tuesday
We will look at a simplified form of the air-interface specification for a common (CDMA) radio system. This describes the overall radio system requirements and enables multiple system operators to co-exist and interoperate. We will examine the key system parameters that have to be measured - parameters such as noise, distortion, sensitivity, selectivity, and interference. We also examine how the IF frequency is chosen. 

Characterization of Receivers

  • Noise in Receivers
  • Selectivity, Sensitivity and Minimum Detectable Signal
  • Nonlinearities and Third-Order Intermodulation Distortion
  • Reception in the Presence of Interferers
  • Dynamic Range and How to Improve It with AGC

Characterization of Transmitters

  • Power and Harmonic Distortion
  • Spurious Products
  • ACPR, Spectral Regrowth and Linearity with Different Modulation Formats
  • Efficiency

Frequency Selection

  • The Image Frequency
  • Choosing the Correct Intermediate Frequency

Wednesday
Next, we will see how these system parameters can be met by assembling a number of components. We will turn to their data sheets to discover how each is characterized, and examine the tradeoffs involved in selecting them. We will extract key defining features that describe the behaviour of each circuit, and then simulate both the component and the system in the systems simulator. 

Systems Simulation - Behavioral Modeling
Simulation of a Dual-band CDMA Superhet Radio Receiver

  • Spreadsheet-based Linear Systems Analysis
  • Calculation of Sensitivity and Dynamic Range
  • Systems Simulation to Compare with Linear Analysis
  • Using AGC to Increase the Dynamic Range
  • Effect of Changing the Gain, Intercept Point, and Filtering

Mixers

  • Spurious Analysis
  • Image Reject and Single Sideband Mixers
  • I-Q Modulators and the Importance of Quadrature
  • Basics of Mixer Design and typical mixer problems

Thursday
We will explore how the key RF functions of amplification, frequency synthesis (oscillation), and frequency translation (mixing) are achieved at the circuit level. This process will highlight some of the key tradeoffs in design, for example, between the power, efficiency, and linearity in a transmitter, and enable us to model these tradeoffs. We will focus on discrete design and review some IC designs. 

Oscillators

  • Basic Concepts of Oscillator Design
  • Deriving the VCO Tuning Curve and Explaining Mode Hopping
  • Phase Noise in Oscillators and its Impact on Communications Systems
  • Calculating Allowable Phase Noise from System Specifications

Power Amplifiers

  • Design Tradeoffs between Linearity, Power, and Efficiency
  • Classes of Amplifier Operation
  • Simulation of Spectral Regrowth with Different Modulation Formats

Friday
Finally, we look at putting everything together, including the modelling of a complete communications link. We will consider a variety of challenges facing the systems designer; we examine some 'real' air interface specifications, and we work an example of the complete design process, from air interface specification through to circuit design.


The Link Budget

  • Modelling a communications link and understanding the tradeoffs

Simulation of a Direct Conversion Receiver

  • Trade-off between Modulation Scheme, Data Rate, RF Bandwidth, 
    Channel Filter, Power, Noise, Phase Noise, and Bit-Error Rate

Interpreting Air Interface Specifications - the complexity of CDMA

  • CDMA Air Interface Specifications (Narrowband and Wideband)

Review of some technical papers

  • Design Considerations of Typical Wireless GaAs and CMOS Chip Sets


Book
Dr Rowan Gilmore and his colleague Dr Les Besser have written two books that they recommend, however, the books are not compulsory for the course:

Publisher: Artech House 
Title: Practical RF Circuit Design for Modern Wireless Systems
Volume I: Passive Circuits and Systems
ISBN 1-58053-521-6   (2003)
Title: Practical RF Circuit Design for Modern Wireless Systems
Volume II: Active Circuits and Systems
ISBN 1-58053-522-4   (2003)

Students may order the books over the Artech House website, http://www.artechhouse.com and receive a 15% discount by entering the promotion code "CEI" in the online order form.




citatteckenSaid about the course from previous participants:
"Interactive teaching, good with simulations examples."
"Simulations and workshops are refreshing to have."
"Very good mix between system point of view and circuit / schematic point of view - very useful for my daily work."
"Very good notes for reference after the course."


CEI-Europe AB, Teknikringen 1F, SE-583 30 Linköping, Sweden Phone +46-13-100 730 Fax +46-13-100 731 cei@cei.se