Turbo driven design

Cambridge Consultants has developed a software program that accelerates the selection of turbo codes for wireless communication systems. Turbo codes are a class of recently-developed high-performance error correction codes finding use in applications where designers seek to achieve maximum information transfer over a limited-bandwidth communication link in the presence of data-corrupting noise.



Called TurboDesigner, the tool reportedly addresses the real-world issues that electronic design teams implementing wireless basestations and terminals face when looking to adopt a turbo code based forward error correction (FEC) strategy – allowing the rapid simulation of application-specific coding/decoding.



Available as an element of Cambridge Consultants’ design services, the software can rapidly reveal the optimum FEC strategy, potentially eliminating weeks of complex design and evaluation using conventional methods such as Monte Carlo simulation.



The new MATLAB-based software can speed and simplify the adoption of turbo codes, which have the potential to generate step-function improvements in wireless system performance with minimal impact on product bill of material costs.



“Our experience has taught us that the right turbo coding implementation can double the coverage or data rate of a wireless system, or halve the amount of transmission power required”, says Monty Barlow, DSP Group Leader with Cambridge Consultants. “The technology is extremely desirable – but the problem comes with real-world implementations of decoders – especially those designed for high data rate applications like WiMAX. There are a large number of factors a designer needs to tweak, each with its own subtle effect on performance and cost. This software produces accurate and quick measurement of Turbo code performance”.



The TurboDesigner package offers a large selection of Turbo encoding and decoding options, with a simple user interface that allows configuration of parameters to understand their effects, including MAP (Maximum A Posteriori) algorithm choice, mathematical precision, windowing length, iterations, block length, and channel type. Highly efficient C-compiled libraries then provide speedy simulations of results.



Once a choice of code has been made, the package will also synthesise realistic test vectors for HDL simulations, and analyse the outputs from the simulations – providing project teams with a high integrity basis for subsequent decisions on hardware implementations in ASICs or FPGAs for example.



Developed to support its wireless system design consultancy, TurboDesigner is freely available to clients as an element of the advice or development services offered by Cambridge Consultants.



“Shrinking silicon costs are now enabling wider exploitation of the relatively new technology of Turbo codes”, adds Monty Barlow. “For us, the first major focus has been for WiMAX development work, where no suitable off-the-shelf cores exist and we need to design our own hardware – but we also expect Turbo codes to be a significant enabler for other emerging wireless systems such as digital broadcasting, and even UWB”.