Journal of Emerging Technologies in Web Intelligence Contents

116 JOURNAL OF EMERGING TECHNOLOGIES IN WEB INTELLIGENCE, VOL. 2, NO. 2, MAY 2010II. WHAT IS A SOFTWARE RADIO?Joe Mitola, who came up with the term Software Radiodefines it as "A radio whose channel modulationwaveforms are defined in software. That is, waveformsare generated as sampled digital signals, converted fromdigital to analog via a wideband DAC and then possiblyup converted from IF to RF. The receiver, similarly,employs a wideband Analog to Digital Converter (ADC)that captures all of the channels of the software radionode. The receiver then extracts, down converts anddemodulates the channel waveform using software on ageneral purpose processor." [2]The software radio, by his definition, should have aslittle hardware as possible.A Software Radio consists of a receiver and atransmitter. For the reception case as shown in “Figure 2.” [1], when the Antenna receives the signal, it passes thesignal to the receiver section for filtering and separatingthe signal from noise and interference. The signal is thenconverted to a desired frequency and amplitude which iscompatible with the analog to digital converter (ADC),and finally to digital data. The digitized data is thenprocessed using digital signal processing techniques forfurther use.For the transmission process as shown in "Figure 3.[1], the software programmable digital signal processingtechniques are used for generating the modulatedsignal(s) in the digital domain. The digital samples arethen converted to analog signal using Digital to AnalogConverter (DAC) and then amplified to the appropriatevoltage, current or power before transmission through theantenna.III. COMPONENTS OF A SOFTWARE RADIOSoftware Radio provides a flexible radio architecturethat makes it re-programmable for different usages withno or minimal change in the hardware. This is supportedby features like interference rejection techniques,encryption, voice recognition and compression, softwareenabledpower minimization and control, differentaddressing protocols and advanced error recoveryschemes.The technology provides the flexibility to combinedifferent grades of hardware and software to strike theright balance between cost and network resilience. Thereconfigurable blocks in Software Radio allows easychanges to the radio’s fundamental characteristics such asmodulation types, operating frequencies, bandwidth,multiple access schemes, source and channelencoding/decoding methods, frequency spreading/despreadingtechniques, and encryption/decryptionalgorithm.The various components of a software radio are shownin “Figure 4. and described below:Figure 2. Radio Signal Reception ProcessFigure 3. Radio Signal Transmission Process© 2010 ACADEMY PUBLISHER