VERIFICATION AND VALIDATION (V&V) ON MILITARY SDR SYSTEMS
SDR, since its theoretical definition by J. Mitola, has been really appealing for the military communications. The possibility to move forward from the legacy radio devices, where all the functionalities were directly embedded in the hardware, towards a new type of radio that allows reconfigurability and flexibility is seen as a Deus ex machina in the complex and crowded panorama of tactical communications. The possibility to execute different waveforms on the same platform can potentially prolong the lifecycle of an operational radio for several years. The possibility to port the same waveform to different hardware, on the other hand, has twofold implications: it allows the re-use of the same waveform, maximizing the return on investment for the developers and, in addition, it allows decoupling the radio manufacturer from the software developer, potentially creating a new market for the waveforms development and procurement. Similarly to what has been commonly experienced in the smartphone market, where Apps are developed independently by the vendor of the terminal, in the future, SDR waveforms might be developed by different subjects, even outside Industry (e.g. universities and research centers) and then ported on an existing SDR platform. The "SDR revolution" is anyway not feasible as long as common development rules for waveforms and common interfaces between the waveform and the underlying hardwarewill be clearly defined. The most relevant contribution in this sense was the definition of the Software Communication Architecture (SCA), published and maintained by the Joint Tactical Networking Centre (JTNC). The SCA defined a set of requirements and rules both for the development of waveforms and for the software definition of processing elements and functions within the host platforms, though leaving to implementers the possibility to choose between different hardware and software solution for the implementation of a SCA-compliant SDR solution. SCA, rapidly became a de facto standard in the military panorama, as it has been widely adopted for the major military SDR programmes also in Europe, mainly in its version 2.2.2. SCA 2.2.2 was designed to meet the stringent requirement of military communications, in terms of security,timing accuracy, real time behavior and it was not able to spread widely outside this context for several years, mainly because of the overhead it imposes to the applications. Today SCA, in its version 4.1, has been published in the US as an emerging standard and its evolution is also supported by the Wireless Innovation Forum. One of the goal of the SCA 4.1 is to define profiles that allows its implementation in devices with limited processing resources, meeting the needs of small form factor devices in the military context and projecting towards applications outside the military. Nevertheless, some other emerging standards are facing the military SDR market, as possible alternatives to SCA. From the point of view of a procurement agency (like MoDs are in the context of military communications),SDR offers significant benefits but, at the same time, it raises new issues and challenges. First, the transition to the software implementation of some functions of the radio platform, requires the development of new testing skills inside the Defence panorama. Each service (i.e. Armed Force) in the Italian Defence, developed during the years, its verification and validation (V&V) facilities, holding a proven experience in the testing methodologies for military radios. The transition to SDR requires that radio testing skills are enhanced with software verification and signal processing skills, as many of the function of new radios are not only performed in software but they also offer the possibility to perform inspection on their behavior. The military procurement strategy for SDR is today closely linked to SCA-based architectures. For these architectures new waveforms have been developed. The ability to test these waveforms,prior to their porting on the final hosting platforms, requires the verification of the compliance of the software modules to the rules of the underlying software architecture (SCA-based). This means that the verification strategy shall comprise the ability to verify that the SCA implementation of a software component is properly performed, assuring future compatibility of the component with the other elements of the waveform and of the platform. After the aforementioned V&V steps, carried out usually during the development of the SDR system or of one of its component (platform, waveform), the complete system is usually delivered to the test facility to undergo a number of tests analogous to that performed on the legacy systems: they span from testing the behavior of the radio over the air, to environmental and electromagnetic compatibility (EMC) testing, to interoperability testing with existing communication systems, where applicable. These activities are usually performed through "live fire exercise", how they are called in military jargon: the system is deployed into an environment that tries to recreate as much as possible the operational scenario and tested under realistic conditions, by the operators that will employ it in real operations soon afterwards. In response to these needs, the Italian MoD has identified the development of a governmental capability for SDR V&V as a strategic pillar and has consequently funded the establishment of a dedicated laboratory (called LANCERS), based on a cooperation between CSSN ITE, a research and experimentation center of the Italian Navy located in Livorno and CNIT (Consorzio Interuniversitario per le Telecomunicazioni) where experimentation and research on tools and technicques for SDR V&V are performed. The laboratory has developed with the time also some collaboration with industries involved in the SDR market. This work summarizes the outcomes of the activities carried out in the LANCERS laboratory, regarding methodologies, tools and experimentation oriented to V&V of military SDR. After providing a brief overview of the major programmes and stakeholders of the military SDR panorama in chapter 1, an analysis of the domains of application of the T&E strategies for SDR will be identified in Chapter2. Chapter 3 will provide an in depth description of the tools and procedures developed at LANCERS lab for military SDR test and evaluation. Different tools, addressing the needs of different phases of SDR development, will be presented, together with the design process that brought to their creation and some results of real applications of these tools. Chapter 4 will present a field testing campaign performed as a necessary complement to the lab test activities listed in chapter 3. Chapter 5 will draw the conclusions and present future work plans for further improving the tools and procedures presented. For some testing activities the presentation of the results will be limited, due to the fact that the disclosure of information related to some particular SDR product is at the moment of writing this thesis yet subject to restrictions. Provided results will be anyway sufficient to provide the reader with a good understanding of the functionalities and applicability of the presented tools and procedures.
