Vanu G. Bose

Virtual radios

Conventional software radios take advantage of vastly improved analog to digital converters (ADCs) and digital signal processing (DSP) hardware. Our approach, which we refer to as virtual radios, also depends upon high performance ADCs. However, rather than use DSPs, we have chosen to ride the curve of rapidly improving workstation hardware. We use wideband digitization and then perform all of the digital signal processing in user space on a general purpose workstation. This approach allows us to experiment with new approaches to signal processing that exploit the hardware and software resources of the workstation. Furthermore, it allows us to experiment with different ways of structuring systems in which the radio component of communication devices is integrated with higher-level applications. This paper describes the design and performance of an environment we have constructed that facilitates building virtual radios and of two applications built using that environment. The environment consists of an input/output (I/O) subsystem that provides high bandwidth low latency user-level access to digitized signals and a programming environment that provides an infrastructure for building applications. The applications, which exemplify some of the benefits of virtual radios, are a software cellular receiver and a novel wireless network interface.

The SpectrumWare approach to wireless signal processing

The SpectrumWare project is applying a software oriented approach to wireless communication and distributed signal processing. Advances in processor and analog-to-digital conversion technology have made it possible to implementvirtual radios that directly sample wide bands of the RF spectrum and process these samples in application software. The elimination of dedicated hardware introduces tremendous flexibility into a wireless communication system. Our approach goes further than the software implementation of traditional signal processing functions. We use processor and network memory to temporally decouple the sample streams from the software modules so that the bulk of the processing can be realized within virtual time programming environments. Decoupling relaxes the temporal constraints on the processing algorithms and their execution. This paper describes the SpectrumWare concept, our experimental approach, and the implications that this approach has for wireless signal processing algorithms.

SpectrumWare: a software-oriented approach to wireless signal processing

The SpectrumWare project is applying a software oriented approach to wireless communication and distributed signal processing. Advances in processor and analog-to-digital conversion technology have made it possible to implement virtual radios that directly sample wide bands of the RF

Methods for in Vivo Tissue Electroporation Using Surface Electrodes

AbstractElectroporation of tissues has many potential biomedical applications, including transdermal and targeted drug delivery. Although there are established protocols for electroporation of single cells, electroporation of tissues remains largely unexplored. Here we describe methods for in vivo tissue electroporation with surface electrodes, where either (a) molecules are provided at the outer surface of skin and electroporation is caused in order to transport molecules across the skin or (b) molecules are injected into an animal and internal tissue cells are electroporated to enhance up-take of the injected molecules. Factors considered in our experimental design include selection of electrode material and electrode/tissue geometry. Electrode materials were used which could accommodate a high instantaneous current density and were expected not to form harmful electrochemical products. Due to the complex heterogeneous nature of tissues, the choice of electrical pulse parameters was guided by, but not b...

The impact of software radio on wireless networking

A software radio is a wireless communications device in which some or all of the physical layer functions are implemented in software. The flexibility provided by the software implementation enables a single device to interoperate with other devices using different wireless physical layer technologies, by simply invoking the appropriate software. A mobile computing device equipped with a software radio would have access to a wide range of connectivity options including cellular, wireless LAN and satellite systems. This would not only enable seamless anytime, anywhere connectivity, but also provide users the flexibility of choosing from the available connectivity options to best suit their price/performance requirements. Most software radio research to date has been driven by military and commercial cellular applications. Mobile networking applications require additional functionality present new software radio design constraints. This paper reviews existing software radio research, describes the SpectrumWare software radio system and identifies some important research challenges that must be addressed in order to apply software radio research to mobile networking applications.

Next century challenges: RadioActive networks

A key challenge facing wireless networking is to utilize the spectrum as e ciently as possible given current channel conditions and in the most e ective way for each application. This is di cult to achieve with existing wireless devices because physical layer functionality is xed, while channel conditions and applications can change rapidly. Instead, we argue that RadioActive networks, an adaptable wireless network architecture which draws on the strengths of software radios and active networks, are needed to meet this challenge. Active networks provide a framework for programming network services, and software radios extend this programmability into the physical layer. We believe that this approach will o er signi cant improvements in functionality and performance over todays wireless networks because it is no longer necessary to design a priori with pessimistic assumptions that describe worst case conditions. In this paper, we outline our vision, the opportunities it a ords, and the challenges that must be tackled before it can become a reality.

Virtual Sample Processing: Extending the Reach of Multimedia

Traditional multimedia systems deal with only a few basic media: text, graphics, audio and video. However, many other types of media, such as ultrasound, infrared and RF signals, can be represented by streams of data samples and processed within multimedia applications. In this paper, we introduce some of these new media domains and identify interesting opportunities enabled by their software-based processing. We also describe our SpectrumWare testbed for experimenting with these new media types and report on our experience to date.We believe that the time has come to broaden the scope of ‘multimedia’ to include any form of sampled information. Advances in processor and analog-to-digital conversion technology have brought raw sample streams within the grasp of desktop computers and media processing systems. Coupling these new media types with software-based processing allows the construction of virtual devices that can handle different sample sources, modify their behavior based on information extracted from the media, and transform information between media domains.

The SpectrumWare testbed for ATM-based software radios

This paper describes the SpectrumWare testbed and two experimental systems we are developing: an ATM-based wideband receiver and the receive side of a GSM base station. These projects leverage recent advances in processor and analog-to-digital conversion technology that have enabled a software-oriented approach to wireless communication and distributed sample processing.