Software turns to ultrawideband design

Available now from Ansoft Corp is an ultrawideband design library for designers of multiband orthogonal frequency division multiplexed radio systems.

Available now from Ansoft Corp is an ultrawideband (UWB) design library for designers of multiband orthogonal frequency division multiplexed (OFDM) radio systems.

The kit, for use with Ansoft Designer, allows engineers to generate and detect Multiband OFDM Alliance (MBOA)-compliant OFDM waveforms for system- and circuit-level simulations.

Using behavioural models for all baseband and nonlinear RF elements, the kit enables the simulation of UWB radio systems.

In addition, users can perform dynamic cosimulations with detailed, transistor-level descriptions of analogue and mixed-signal blocks using Ansoft's Nexxim circuit simulator.

Multiband OFDM is a new breed of UWB physical layer (PHY) technology that will unlock opportunities in computer networking, home entertainment and media sharing.

Perhaps the most exciting is the development of wireless USB devices that eliminate cables used to download and share data, electronic photographs and video.

Future electronic devices, such as digital cameras, camcorders, laptop computers and set-top boxes, will have a wireless USB solution.

This large market opportunity has spawned numerous design starts for wireless USB chipsets.

"Ansoft developed the MBOA design kit as part of an ongoing project to design and produce a direct-conversion UWB radio reference design with our partner UMC", said Dr Lawrence Williams, Director of Technical Business Development at Ansoft.

"The library allows designers to evaluate radio performance with true MBOA-compliant waveforms".

The library enables Ansoft Designer users to simulate all analogue and digital signal processing (DSP) functions in the MBOA transmitter and receiver.

Engineers can use the library to generate and detect MBOA-compliant waveforms and apply them at the behavioural level, the transistor circuit level or both.

For example, it is possible to predict cochannel and adjacent-channel interference and to compute error vector magnitude (EVM) and bit error rate (BER) at the receiver for any combination of behavioural- and transistor-level blocks.

This true co-simulation capability allows users to have the system simulator dynamically drive parametric circuit and electromagnetic simulations.

Many system designers use Matlab for radio system and link analysis.

Ansoft's products directly interface with such simulations.

The new UWB design kit enables designers to include detailed simulations of all linear and nonlinear effects including impedance mismatch between radio blocks, gain compression of amplifiers, spurious response of mixers and noise figure of low-noise amplifiers.

These higher-order and frequency-domain effects are very challenging to model with other simulators and are easily computed using Ansoft technology.

Bit- and frame-accurate models for DSP blocks like the scrambler, convolutional encoder, puncturer, bit interleaver, constellation mapper and FFT processor, have all been implemented in the library.

This and additional features include: bit- and frame-accurate models for IEEE802.15.3a Multiband-OFDM UWB; support of all datarates from 53 to 480Mbit/s in both standard and streaming modes; time and frequency spreading combined with puncturing realise various rates; and high-level library models for bit- and frame-accurate transmitter for users that do not need to bore into detailed models; bit-accurate, high-level models for transmitter and receiver signal processing.

The library also features: channel models for path loss, multipath Rayleigh fading (outside) and exponential distributions (indoor); lower-level transmit/receive library models for the detailed designer: OFDM (IFFT/FFT), gray coded QPSK modulation, scrambler, convolutional coder with puncturing, Viterbi decoder, pilot/guard inclusion, cyclic prefix, preamble/header generation and payload formatting; framing with packet synchronisation, frame synchronisation, channel estimation, CRC check sequences and alignment; and time/frequency hopping patterns for all five band groups from 3.1 to 10.6GHz.

The Ansoft UWB design kit is available to all Ansoft Designer and Nexxim customers currently on maintenance.

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