1 SDR4all: Software Defined Radio Made Easy Leonardo S. Cardoso 1 , Sylvain Azarian 2 , Pierre Jallon 2 and Mérouane Debbah 1,2 1: SUPELEC, Gif-sur-Yvette, France 2: SDR4all, Paris, France Abstract: We describe the potential of SDR4all (Software Defined Radio for all) to reduce the innovation cycle related to the design and implementation of flexible radio algo- rithms and software defined radio. SDR4all is a programmable software tool with multi-input multi-output (MIMO)-capable radio cards for wireless researchers, students and engineers. It enables to implement in software any wireless scheme between two laptops. Using a flexible orthogonal frequency division multiplexing (OFDM) based implementation example, we de- scribe the tool and show the performance of the transmission on a real wireless channel at 2.4 Ghz ISM band. Keywords: SDR4all, flexible radio, SDR, OFDM I. MOTIVATION One of the problems that make the conception to devel- opment cycle so slow in research and development (R&D), particularly in the telecommunications field, is the fact that there is a big gap between the theory and the practice. Telecommunication theorists usually ignore critical aspects of the implementation of radios that are usually overlooked in telecommunication courses. Bridging the gap between theory and practice can reduce the time-to-market of ideas. Matlab R  has been proactive in this sense, offering tools and means to shorten the development cycle and allowing engineers to test their conceptions right inside their interface. However, in the area of telecommunications, not many options fill this need. While solutions do exist, they are generally hard to use and/or expensive. Existing projects and platforms (such as [1], [2], [3], [4]) aim at a building a configurable radio platform for the implementation and test of new technologies. In spite of their impressive capabilities, they are generally restricted to the use by professionals due to complicated pro- gramming languages (C, Assembly, VHDL, etc...), expensive hardware and testing equipment, lack of general knowhow in hardware development and radio frequency (RF) circuitry and to the fact that porting high level code to existing RF platforms is very time consuming. The need by telecommunication re- searchers/engineers/students for an easy to use tool for simple algorithm testing are left uncovered. Briefly, their needs are: • Stress-test ideas with realistic constraints; • Use real “models” of channels; • Provide a proof of concept of an algorithm; • Become acquainted with the issues related to radio sys- tems; • Create a practical view of the problems targeted; • Verify the validity of the initial problem assumptions; • Analyze the feasibility of the algorithms. In this contribution, we propose SDR4all [5] as a solution to fill this gap. The SDR4all is based on the concept of software defined radio (SDR) [6], [7], [8] to enable the implementation of algorithms that will be tested with real transmissions using actual hardware transceivers. The idea of this testbed is to enable students/researcher to test their ideas and algorithms on real transmissions while still keeping the simplicity of a high level programming language environment. In the remainder of this work we will present the evaluation tool in detail in section II . We will then present an example transmission/reception chain and show its characteristics and features in section III as a means to showcase the capabilities of SDR4all. We then discuss about its metrics and results in section IV. We conclude this contribution in section V II. SDR4 ALL EVALUATION TOOL SDR4all is composed of a USB plug and play hardware part, and a software part. The hardware part is in charge of the RF and sampling processing while the radio transceiver’s physical layer (PHY) is software driven, running in a computer. In the following we will describe in detail the hardware and software components of SDR4all. A. SDR4all Hardware The hardware was developed specifically for the purposes of SDR4all [5] and consists of a small, MIMO-expandable, USB radio card. These cards are divided into two parts: a controller board and one or several stacked RF boards (up to four) in SISO or MIMO configuration. The mother- board is responsible for the RF control, communication over the USB link and decimation/interpolation. The RF board is responsible for the analog-to-digital (AD) and digital-to- analog (DA) conversions and RF circuitry. The controller board is built around the commercially available development board [9] and is composedof a Xilinx SPARTAN-3 FPGA and a Cypress EZ-USB-Microcontroller. It supports high-speed USB 2.0 links (up to 480 Mbits/sec). The RF board is designed to plug on top of the FPGA board using its 2x32 pin headers. It is composed by an AD (AD9251), DA (MAX5873), MAX 2830 RF, a programmable clock generator (AD9510) and glue logic. SDR4all RF sup- ports the 2.4 GHz ISM band, chosen since it shares the same characteristics with the widely popular 802.11(b/g), bluetooth