Reconfigurable Radio System (RRS) / Software Defined Radio (SDR)

The first revolution in radio technologies was the transition from analog to digital. The second one will be the transition from digital to software-based”.
A Software Defined Radio (SDR) system is a radio communication system where components that have typically been implemented in hardware (i.e. mixers, filters, amplifiers, modulators/demodulators, detectors. etc.) are implemented using software. While the concept of SDR is not new, the rapidly evolving capabilities of digital electronics are making many processes that were once only theoretically possible practical. (Source: Wikipedia)
A common misconception is that SDR is the new US Army Combat Radio, in the sense of SCA-compliant Reconfigurable Radios. To avoid this, non-SCA Software Defined Radios are often called Reconfigurable Radios, or RRS.

Cognitive Radio (CR)

Cognitive Radio is a novel principle in wireless communications, where a radio node continuously senses the radio spectrum and dynamically changes its transmission/reception parameters to overcome interference with licensed/unlicensed spectrum users. It is an evolutionary enhancement of Software Defined Radio, where the Radio Frequency parameters are modified not according to commands by a user, but instead according to an intelligent, automatic decision making process that is constantly aware of the spectrum conditions and adapts the radio set parameters accordingly. Obviously, SDR is an enabling technology for Cognitive Radio.

Flexible Spectrum Management

Studies have found that the 3-axis spectrum usage in frequency, time and space is rather scarce (in the area of 6%), leaving a scarce and expensive resource (RF Spectrum) underutilized. This is believed to be the result of rigid spectrum allocation.
Cognitive Radio would enable Flexible Spectrum Management, an approach that tries to solve the spectrum scarcity problem by allowing intelligent radio terminals to communicate on frequency bands licensed for a different use in case those frequency bands are not utilised by their owner at that point in time and space. The legal owner of the spectrum will still have priority on the use of the spectrum, without the need to upgrade existing infrastructure in any way.

Wireless Interoperability

Wireless Interoperability is the ability of legacy radios and software defined radios (SDR) based on the same radio standard to exchange voice and data. It is often called Over-the-Air Interoperability.
Three possible scenarios need to be taken into account:

  • the interoperability between SDR Sets comprised of the same (ported) Waveform but different SDR Platforms
  • the interoperability between SDR Sets running different Waveform Applications implementing the same Radio Standard
  • interoperability between an SDR Set and legacy radios implementing the same Radio Standard

Platform Reconfigurability

An SDR Set is divided into Platform and Waveform(s), with the Platform being composed of the Hardware Platform and a Middleware (Software) Layer, including the Operating System, Device Drivers, Services, a Reconfiguration Infrastructure, and more.
The concept of Platform Reconfigurability, which is essential for the technology of Software Defined Radio, implies the ability to change the parameters of the Hardware Platform and of the Platform Support layer, in order to change the SDR Set’s behaviour as required.

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