| Software-Defined
Radio (SDR) |
Definition
Software-Defined Radio (SDR) Forum defines SDR technology as "radios
that provide software control of a variety of modulation techniques, wide-band
or narrow-band operation, communications security functions (such as hopping),
and waveform requirements of current & evolving standards over a broad frequency
range." In a nutshell, Software-Defined
Radio (SDR) refers to the technology wherein software modules running on a generic
hardware platform consisting of DSPs and general purpose microprocessors are used
to implement radio functions such as generation of transmitted signal (modulation)
at transmitter and tuning/detection of received radio signal (demodulation) at
receiver.Software-Defined Radio (SDR) is a rapidly
evolving technology that is receiving enormous recognition and generating widespread
interest in the telecommunication industry. Over the last few years, analog radio
systems are being replaced by digital radio systems for various radio applications
in military, civilian and commercial spaces. In addition to this, programmable
hardware modules are increasingly being used in digital radio systems at different
functional levels. SDR technology aims to take advantage of these programmable
hardware modules to build an open-architecture based radio system software.
SDR technology facilitates implementation of some of the functional modules in
a radio system such as modulation/demodulation, signal generation, coding and
link-layer protocols in software.SDR technology can
be used to implement military, commercial and civilian radio applications. A wide
range of radio applications like Bluetooth, WLAN, GPS, Radar, WCDMA, GPRS, etc.
can be implemented using SDR technology. This whitepaper provides an overview
of generic SDR features and its architecture with a special focus on the benefits
it offers in commercial wireless communication domain. This
section gives a brief overview of a basic conventional digital radio system and
then explains how SDR technology can be used to implement radio functions in software.
It then explains the software architecture of SDR. The digital radio system
consists of three main functional blocks: RF section, IF section and baseband
section. The RE section Consists of essentially analog hardware modules while
IF and baseband sections contain digital hardware modules.SDR
has generated tremendous interest in the wireless communication industry for the
wide- ranging economic and deployment benefits it offers. Following are some of
the problems faced by the wireless communication industry due to implementation
of wireless networking infrastructure equipment and terminals completely in hardware:- 1.Commercial
wireless network standards are continuously evolving from 2G to 2.5G/3G and then
further onto 4G. Each generation of networks differ significantly in link-layer
protocol standards causing problems to subscribers, wireless network operators
and equipment vendors. Subscribers are forced to buy new handsets whenever a new
generation of network standards is deployed. Wireless network operators face problems
during migration of the network from one generation to next due to presence of
large number of subscribers using legacy handsets that may be incompatible with
newer generation network. 2.The
network operators also need to incur high equipment costs when migrating from
one generation to next. Equipment vendors face problems in rolling out newer generation
equipment due to short time-to-market requirements.
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