Experiences from the Iris testbed in dynamic
spectrum access and cognitive radio experimentation
Linda E. Doyle, Paul D. Sutton, Keith E. Nolan, Jo¨rg Lotze, Barıs¸ ¨Ozgu¨l,
Thomas W. Rondeau∗, Suhaib A. Fahmy∗∗, Hicham Lahlou, Luiz A. DaSilva
CTVR The Telecommunications Research Group, University of Dublin, Trinity College, Ireland
∗Center for Communications Research in Princeton, N.J. USA
∗∗ School of Computer Engineering Nanyang Technological University, Singapore
Abstract—The focus of this paper is an experimentation plat-
form known as Iris that has a runtime reconfigurable software
radio at its core. We have employed this platform to enable
a wide variety of tests and experimentation in the fields of
dynamic spectrum access and cognitive radio. The paper charts
the progress of the Iris system since its inception as well as
details of some of the experiments and trials conducted using
this platform. We also discuss the challenges involved in the
development and deployment of a software radio platform that
supports runtime reconfigurability and provide recommendations
for future improvements.
I. INTRODUCTION
To significantly advance research in the field of dynamic
spectrum access and cognitive networking, it is essential
that ideas be translated from paper to working prototype.
This is a challenging and more often than not slow process.
Some of the bold ideas of new spectrum usage regimes are
met with skepticism by some regulators, broadcasters, and
wireless industry, making the prototyping process all the more
important. While the field has grown and matured, it is not yet
obvious that we have found a real home for cognitive radio
beyond the much discussed TV white spaces and there are
many who still doubt the potential of cognitive radio and its
role in the future.
The purpose of this paper is to discuss our ongoing effort
focusing on cognitive radio experimentation and reconfigura-
bility. This effort centres around the use of the Iris runtime
reconfigurable software radio platform, a platform designed
in CTVR in Trinity College Dublin.
Iris is introduced in Section II. The basic system has grown
and advanced over the years and these advances are described
in Section III. An Iris radio consists of a chain of components
and some typical Iris components for dynamic spectrum access
experimentation are presented in Section IV. Section V is a
key section and summarises the major demonstrations which
were based on Iris and highlights three examples in particular.
Section VI gives some brief details of an innovative test and
trial scheme run by the Irish regulator Comreg, that aids
experimentation. Section VII shows how Iris has commercial
potential and section VIII introduces two European research
projects that feature Iris. Section IX discusses both the specific
issues relating to experimentation with Iris as well as the
broader challenges of experimentation in general. Section X
concludes.
II. EARLY HISTORY
Iris was created as a runtime reconfigurable software radio
for general-purpose processors (GPP) using a Windows oper-
ating environment [1]. It was inspired by the SpectrumWare
work at MIT [2]1. Iris is a component-based system. Discrete
signal processing functions such as a digital filter or modulator
are implemented as components with generic interfaces for
lifecycle control, data passing and reconfiguration. These
components are linked together to build radio transmit and
receive chains. an XML file is used to describe the structure
of the components. Both the Iris runtime system and the Iris
components are implemented completely in portable C++.
In contrast with software architectures such as GNU Radio
and the Software Communication Architecture (SCA), Iris was
designed specifically to support maximum reconfigurability
while the radio is running. Iris nodes can therefore carry out
reconfigurations seamlessly in response to observed changes
in the operating environment. Reconfigurability is realised
through a number of different mechanisms. When implement-
ing an Iris component, the radio designer can choose to expose
a number of parameters. While the radio is running, these
parameters can be dynamically reconfigured to adjust the oper-
ation of the component. Alternatively, individual components
can be changed at runtime, as can whole configurations of
components.
The emphasis from the beginning was on ‘ease of design
for developers, the ability to rapidly prototype and tailor a
transceiver implementation, and a GUI that provided a suite
of software radio components and control entities for use in a
design.
It had always been intended that Iris connect to a RF fron-
tend that had minimum functionality, i.e. that the bulk of the
processing take place in Iris. However, initially identifying an
appropriate RF frontend proved extremely difficult. The Wa-
veRunner Plus 253 PMC transceiver model from Red Rapids,
a 70MHz IF radio module, was used and much of its un-
necessary functionality (from our perspective) was bypassed.
1The SpectrumWare work was the basis for the formation of the company
Vanu.
This full text paper was peer reviewed at the direction of IEEE Communications Society subject matter experts for publication in the IEEE DySPAN 2010 proceedings
978-1-4244-5188-3/10/$26.00 ©2010 IEEE