A channel access protocol for tactical IP networks using software defined VHF radios

Military ad-hoc wireless networks are becoming increasingly common in today's world. Military networks have requirements for security, jamming and spoofing resistance, voice transmissions, and range that are often not feasible to achieve with off-the-shelf commercial products. These networks may also require multiple users to share a variety of services such as file transfer, e-mail, situational awareness reports, and voice over a single channel. Performance is often limited by the number of devices and interfaces at each station. With software-defined radios that incorporate unprecedented digital signal processing power, coupled with industry standard interfaces such as the Internet protocol (IP), the radio chassis can literally become a "system in a box". Channel access protocols can also benefit greatly from being integrated with the radio modem. The RF Communications Division of Harris Corporation has developed a black-side (post-encryption) channel access protocol based on the well-known MACA protocol. This protocol performs well on real-world networks facing such challenges as voice priority over data, "hidden nodes", and varying channel conditions. Wireless IP networking capability based on this protocol has been implemented and fielded in Harris's software-defined Falcon II Tactical Radios. This paper discusses the benefits/tradeoffs of embedded black-side channel access protocols and presents test results from a typical military communication system based on the Harris RF-5800V-MP radio.