| Advances in analog-to-digital conversion and digital signal processing may allow new wideband receiver architectures to be built. For example, a receiver could sample a much wider bandwidth than is needed for a single user to communicate. This wideband receiver might be able to simultaneously digitally demodulate the signals of multiple users that occupy different subbands. If a transmitted signal uses frequency hopping, the receiver could generate useful side information for the decoding process by continually monitoring the level of interference in all subbands.
Because the analog-to-digital converter (ADC) has finite resolution and operates over a limited range, it is possible that a strong signal can prevent weaker ones from being reliably captured. If multiple users are communicating, this interference may be caused by the near/far problem. However, a jammer can also attempt to disrupt communication by taking advantage of the ADC's limitations. Because of the receiver's wide bandwidth, the jammer might not even need to occupy a frequency subband used by the signal of interest. Instead, it might only transmit in the much wider band sampled by the receiver with sufficiently high power to overload the ADC. The susceptibility of wideband digital receivers to jammers attacking their ADCs will be considered. Receiver implementation and signaling techniques to reduce the effectiveness of this jamming threat will also be examined. |
| Frederick J. Block received the B.S. (summa cum laude), M.S., and Ph.D. degrees in electrical engineering from Clemson University, Clemson, SC. He is currently a Member of the Technical Staff at MIT Lincoln Laboratory, Lexington, MA. His research interests include spread-spectrum communication and ad hoc networks. Dr. Block has been a National Science Foundation Fellow, an AFCEA Fellow, an R. C. Edwards Fellow, and a Holcombe Scholar. He is a member of Tau Beta Pi and Eta Kappa Nu and has received the Harris Graduate Research Award. |