Software Radios for Wireless Networking

This paper describes a novel architecture for building software wireless network interfaces. These interfaces, implemented in user-level software, run on oo-the-shelf PCs and replace all of the link and many of the physical layer functions typically implemented in dedicated hardware on a network interface card (NIC). They provide all of the processing needed to transform between wideband IF signals and network packets. Moving this functionality into user-level software has several advantages. Among other things, it makes it easy to implement protocols that adapt to diierent applications and environmental conditions. Our approach is compatible with the existing OSI protocol stack, but supports a ner granularity of layering. This ner granularity makes it possible for our NIC to dynamically change functions, such as modulation technique, that are xed in other NICs. It also ooers interfaces that facilitate interoperation with a variety of other systems, e.g., codecs. We also present a brief description of our architecture which allows these software NICs to be built, as well as a sample NIC that runs on a PentiumPro, designed to interoperate with a commercial 2.4 GHz ISM band frequency hopping spread spectrum radio.