The implementation of network centric warfare on the battlefield has driven the growing demand for high capacity warfighter communication systems. Although new high capacity SATCOM systems such as WGS are being introduced in the near term, these systems use the interference avoidance paradigm, which fundamentally limits overall network performance. This paper introduces a new wireless networking paradigm called Interference Multiple Access (IMA), developed under the auspices of DARPA. The interference multiple access paradigm exploits multi-access interference to enable revolutionary improvements in wireless communication capacity and latency without the need for infrastructure, coordination, or spectrum preplanning. Simulation and over-the-air test results suggest that greater than 3X increases in network throughput (especially in low SNR scenarios) can be achieved over traditional contention and scheduled-based spectrum access approaches when applied to WIN-T NCW terminals communicating in a mesh topology over the WGS constellation.
A critical component of any video transmission system is an objective metric for evaluating the quality of the video
signal as it is seen by the end-user. In packet-based communication systems, such as a wireless channel or the Internet,
the quality of the received signal is affected by both signal compression and packet losses. Due to the probabilistic
nature of the channel, the distortion in the reconstructed signal is a random variable. In addition, the quality of the
reconstructed signal depends on the error concealment strategy. A common approach is to use the expected mean
squared error of the end-to-end distortion as the performance metric. It can be shown that this approach leads to
unpredictable perceptual artifacts. A better approach is to account for both the mean and the variance of the end-to-end
distortion. We explore the perceptual benefits of this approach. By accounting for the variance of the distortion, the
difference between the transmitted and the reconstructed signal can be decreased without a significant increase in the
expected value of the distortion. Our experimental results indicate that for low to moderate probability of loss, the
proposed approach offers significant advantages over strictly minimizing the expected distortion. We demonstrate that
controlling the variance of the distortion limits perceptually annoying artifacts such as persistent errors.