Software Engineering

Software costs are a significant and growing component of SDR engineering costs. In all but the highest volume applications, the amortized cost of software is a major part of SDR device unit cost. Therefore high-quality software engineering is a major focus and a major competitive advantage of Vanu, Inc.

Bringing modern software engineering techniques to bear on high-speed signal processing is a significant challenge. Traditional approaches to building signal processing software result in high overheads for abstraction, modularity, and similar software engineering techniques. Research by the company's founding team at MIT in the mid 1990s led to a new type of middleware to address these challenges, enabling construction of modular software and reusable components that still achieve nearly the full hardware performance available from the underlying processor platform.

The Vanu, Inc. middleware for software radio, called Sprockit™, differs significantly from traditional middleware systems such as CORBA or COM. Sprockit™ is focused on efficient integration of software modules on a single processor. Integration of multiple processors or machines into a parallel processing architecture is handled at a higher system level to avoid introducing overheads such as failure tolerance and communication buffer management into the high-speed interfaces between successive signal processing modules. Sprockit™ separates high-speed data flows from asynchronous control messaging. Data flows move at predictable rates in a single direction down largely stable pipelines of modules. Data flows are implemented using receiver pull, which maximizes efficiency when receiver and sender are serialized software modules executing on the same underlying processor. Data flows are also optimized for the caches and memory hierarchy of the underlying processor by run-time selection of iteration size. In contrast, control messaging is handled out-of-band, sender-push, and is not limited to flowing down stable pipelines. This better matches the way in which control messages are used and reduces overall software complexity.

In addition to combining modularity and performance using Sprockit™, Vanu, Inc. focuses on effective software engineering throughout the lifecycle of system development and operation. Advanced automated testing runs continuously, 24 hours a day from the start of a development effort, maximizing the chance that software or design errors are detected early in the system lifecycle. Some of the most advanced logging and remote maintenance mechanisms in the industry enable easy analysis of behavior in the field and low-cost rapid upgrades. Use of off-the-shelf servers and standard operating systems significantly streamline the development and deployment process.

Portability

Software portability is the key lever available to dramatically reduce software costs and development time. With portability we need not develop each waveform from scratch for each platform it runs on. Every module that is ported reduces testing cost and time in addition to development.

However, portability does not come for free. It may have costs like using a processor that consumes more power, or software abstraction layers that have computational and memory costs. That is why portability is a design trade rather than an across-the-board requirement.

When we design a system for software portability in expectation of component technology upgrades, we are fundamentally changing the value proposition of the engineering effort. Traditionally in radios, the hardware device is treated as the high-value aspect of the design, with software written to support it. With this alternate design approach, the software is treated as the aspect of the system with lasting value, and a sequence of hardware devices are built to support it.

High software costs combined with Moore's Law component improvement curves force this fundamental change in engineering focus.

SDR devices designed for waveform portability lead to a quantum leap in benefits for users. Portability is what will make it affordable to deploy many waveforms to many platforms and to upgrade platforms over time with improved capacity. This means that a high level of software portability is essential for SDR to deliver the promised transformational impacts on user applications and operations.

These effects justify separating SDR devices designed for a high level of software portability into an independent top-level device category, called SWR for Software Radio to distinguish it from Software-Defined Radio.