The Software Communications Architecture (SCA) mandated by the Joint Tactical Radio System (JTRS) program office provides a software framework for implementing Software-Defined Radio (SDR) platforms.
This framework offers many features to increase the portability of waveforms by including a common operating environment and a set of common services and standardized component interfaces.
Developers of JTRS platforms must conform to the SCA specifications and undergo certification to ensure that requirements have been met. As a result, JTRS radio set developers who require FPGA or DSP devices to achieve the required levels of performance for complex waveforms and multichannel operation, are faced with two choices: either develop custom hardware and build
SCA compliance into it, or buy COTS products and adapt the standard drivers and libraries to SCA compliance. Either choice poses tangible risk and cost factors.
In a nutshell, JTRS defines a system for software-programmable radios for reliable multichannel voice, data, imagery, and video communications. It supports platforms from battery-operated hand-held units in the field to base systems found in headquarters and everything in between.
The system is modular and scalable to allow more bandwidth and channels as needed and must be backwards compatible with legacy radios that it eventually will replace. It supports transparent, dynamic, intra- and inter-networking routing.
JTRS eliminates stovepipe legacy systems where each component is so intimately tied to the next that replacing an outdated component could cause a change to ripple throughout the whole system. It carries real-time information through what the U.S. Army likes to call the last tactical mile to the fighter in the field. In general, it ensures greater success and safety for war fighters through multinational, cross-echelon communications.
JTRS goals also go beyond the battlefield. Some potential applications are U.S. Homeland Security; federal, state, and municipal law enforcement; ambulance and emergency medical technicians; fire fighters; search and rescue land and sea; commercial and private aviation; and international commercial applications.
The JTRS mandates the use of the SCA that allows multiple radio types or waveforms applicable to one hardware platform as well as waveforms that are portable across all platforms. These are two major requirements of the JTRS initiative. Some of the major features or requirements of JTRS are listed on the JTRS site.
SCA Core Framework
Figure 1 shows a very simplified version of the main layers of a JTRS radio set. With it, you can start to get a feel of where all the components come from.
Starting from the bottom and working up, the major components are the following:
- The actual radio hardware that provides all the analog and digital interfaces to the outside world.
- The operating system and middleware.
- The SCA core framework, which is the software that interfaces to the hardware.
- The waveforms that give the radio its specific characteristics needed to satisfy the application requirement.
1. Main Layers of a JTRS Radio Set.
The SCA Core Framework (CF) connects the SCA-compliant waveforms (shown at the top) with the SCA-compliant hardware within the JTRS radio set (shown at the bottom). This allows the platform developers who produced an SCA-compliant radio set and the waveform developers who independently generated SCA-compliant waveforms to expect that the waveforms will function properly with the radio hardware.
SCA Operating Environment
The SCA Operating Environment (OE) is shown in Figure 2. It depicts all the layers of the software and how they interact.
2. SCA Operating Environment
Figure 3 illustrates an expansion of the OE components. These components consist of the CF, the OS, the Board Support Package (BSP), the Common Object Request Broker Architecture (CORBA), the Object Request Broker (ORB), and the Network Services. The SCA recognizes the need for separating the black or secure components of an application from the red or nonsecure components.
So what we have here are two parallel and complete OE sets that exist in the same application to support both black (secure) and red (non-secure) components of the system.
(Click to enlarge)
3. Detailed Breakdown of SCA Operating Environment Click here to see larger image