Chad Scott Bergstrom

Adaptive spectrum exploitation using emerging software defined radios

Radio frequency interference (RFI) caused by commercial and military spectrum crowding is a growing problem for digital battlefield communication systems. Current electromagnetic spectrum planning generally involves static frequency allocations that are difficult to modify after force insertion. Currently, no real time spectrum management systems exist to coordinate the dynamic spectrum environment experienced by mobile military communications. The DoDs plans for the Joint Tactical Radio System (JTRS) indicate that software defined radios (SDR) will be key components of the future battlefield. We investigate battlefield spectrum efficiency problems caused by RFI, and propose near term solutions that exploit the capabilities of emerging software defined radios to provide real time spectrum planning and frequency adaptation.

Emerging software defined radio architectures supporting wireless high data rate OFDM

Orthogonal frequency division multiplexing (OFDM) has been identified as one potential method to enhance the performance of wireless communication links degraded by cosite interference, impulsive noise, and frequency-selective fading. In the past, implementation complexity slowed the development of OFDM for useful commercial and handheld applications. With the advances in semiconductor processing technology and digital signal processing, OFDM is now practical for system solutions including wireless LANs, audio and television broadcasting, and land mobile services. We describe the application of OFDM within software defined radio (SDR) platforms to provide multi-service land mobile radio capabilities. The simple combination of OFDM and SDR provides great flexibility in system configuration, significant reduction in product development cycle time, and very high potential for software reuse.

SDR strategies for information warfare and assurance

As software defined radios (SDR) proliferate and the capability and functionality of radios expand, the opportunities for attack by either side increases. Modern networks are evolving into a combination of wired, wireless, and Internet components with attacks possible on any component against any other component. Understanding those attacks to identify vulnerabilities and formulate defensive approaches is the first step in a comprehensive system design. Furthermore, a complete understanding of adversarial vulnerabilities enables development of offensive strategies that leverage the power of network centric warfare (NCW). Computational capabilities of emerging SDRs provide the means to coordinate attacks against the adversary. Further, these capabilities will enable new methods for overcoming classical attacks against the terrestrial, UAV, and Satcom information systems. Part of the protection strategy for these systems will require that classical information assurance (IA) techniques be distributed to various SDR nodes within the infrastructure.

Wireless multiple access networks for survivable battlefield communications

The future of military radio networks is changing dramatically along with commercial radio systems. Users are demanding higher bandwidths to support video, image, file transfers, and high quality voice. The methods for supplying capacity retain the centralized approach for commercial systems due to improved cell coverage, hand-off requirements, and access to wired-infrastructure. The military has needs for centralized modes for minimal conflict scenarios, however, peer-to-peer modes must remain at a top priority to provide survivable communications. Timely message delivery is critical in military networks, which can have no single points of failure and must be self-organizing to be survivable.