Tag Archives: Radio

Wireless Radio Architecture

Wireless Radio Architecture

As we move forward towards the next generation of wireless protocols, the push for a better radio physical layer is ever increasing. Conventional radio architectures are limited to narrow operating regions and fails to adapt with changing technology. This is further strengthened with the advent of cognitive radio, which needs a more versatile and flexible framework that is programmable within the timing constraints of a protocol. In this research, we present an architecture for Software Defined Cognitive Radio that caters to the specific baseband processing requirements in a changing environment. We aim to provide more flexibility by deconstructing the radio pipeline into a framework of user controlled kernels that can be reconfigured at run-time. This architecture provides the barebones of a OFDM based radio physical layer that can adapt to perform a varied number of tasks in different radio networks. We also present a novel message based real-time reconfiguration method to transmit and receive a wide range of waveforms used in concurrent wireless protocols.

Publications

Wireless@CU – Prototypes

GENI Cognitive Radio Platform

The GENI Cognitive Radio Platform is an active development project that involves ground-up design and deployment of a highly programmable, frequency agile, multi-FPGA, wideband cognitive radio which will be connected to the GENI testbed framework. The basic idea behind this initiative is to make the platform accessible to other researchers using internet to run cognitive radio experiments in a realistic network. CU has teamed up with Rutgers University and Radio Technology Systems in this initiative to build this next generation testbed of cognitive radios.

Following is a demonstration of the latest version of the radio, which can be tuned from 100MHz to 7.5GHz.

GENI Cognitive Radio Prototype- version 1

The earlier version of the radio had the following features:

  • Virtex5-LX50 FPGA – Acts as the motherboard for the baseband OFDM design and ADC/DAC and RF daughter cards.
  • 100Mbps Ethernet to send control and data packet to and from the radio board.
  • Tunable to 2.4GHz and 5GHz ISM band.
  • Complete design and implementation of the OFDM pipeline is done using a combination Xilinx System Generator and ISE tools.
  • Design capabilities include – Non-contiguous OFDM with fine grain control over modulation and bandwidth.
  • Full transmit receive path implemented for OFDM based 802.11a/g packets.
  • Backward compatible with standard off the shelf Wi-FI cards.

We will continue to work on improving the prototype and add new features to achieve the ultimate goal of being a part of a global network testbed.

Nallatech XtremeDSP/Fidelity Comtech SDR

SDR prototype using Nallatech/Fidelity Comtech front-end

Prior to the GENI initiative, wirelesss@CU had been involved in development of basic software defined radio capable of demonstrating frequency agile techniques. The basic SDR was built as a hybrid design with partitioning of DSP algorithms into software and hardware components providing high flexibility as required in SDRs and cognitive radio. The development was carried out using a Nallatech XtremeDSP-IV kit with high speed ADC/DAC chip allowing wideband designs along with a RF front-end box that operates in the 2.4GHz.

Since its deployment in 2007-08, the prototype has been used in various experiments and resulted in a number of publications in the field of  wireless networking, cognitive radio and radio architectures.  Please refer to the publication list under various projects within the wireless@CU research group for more details on the design and development of the SDR prototype.