Alex R. Chiriyath

Inner Bounds on Performance of Radar and Communications Co-Existence

We investigate methods of co-existence between radar and communications systems. Each system typically considers the other system a source of interference. Consequently, the traditional solution is to isolate the two systems spectrally or spatially. By considering a cooperative radar and communications signaling scheme, we derive achievable bounds on performance for a receiver that observes communications and radar return in the same frequency allocation. We assume the radar and communications operations to be a single joint system. Bounds on performance of the joint system are measured in terms of data information rate for communications and a novel radar estimation information rate for the radar.

Joint communications and radar performance bounds under continuous waveform optimization: The waveform awakens

We develop a joint radar and communications performance bound by optimizing waveforms jointly for the simultaneous radar return and communications receiver. We develop radar waveforms that jointly maximize radar estimation rate and communications data rate for a shared spectrum. As an extension to our previous efforts, we consider a parametrically defined radar spectral weighting of the waveform, balancing the potential increase in entropy due to range sidelobes with the potential improvement in main lobe performance. Successive interference cancellation is used to mitigate an in-band communications user signal after the predicted radar return is removed. The emphasis on radar estimation rate and communications rate is varied, and results are obtained using numerical methods.

Joint radar-communications performance bounds: Data versus estimation information rates

We investigate methods of co-existence between radar and communications systems. Since historically each system views the other as a source of interference, the systems are traditionally isolated spectrally or spatially in order to prevent performance degradation. By considering a cooperative radar and communications signaling scheme, we derive achievable bounds on performance for a receiver that observes communications and radar return in the same frequency allocation. These inner bounds on performance will be derived in scenarios where the radar system has to perform target parameter estimation for multiple targets. Additionally, a novel inner bound that maximizes the Fisher information for radar parameter estimation is also derived. Bounds on performance of the joint system are measured in terms of data information rate for communications and radar estimation information rate parameterization for the radar.

Survey of RF Communications and Sensing Convergence Research

Wireless mediums, such as RF, optical, or acoustical, provide finite resources for the purposes of remote sensing (such as radar) and data communications. Often, these two functions are at odds with one another and compete for these resources. Applications for wireless technology are growing rapidly, and RF convergence is already presenting itself as a requirement for both users as consumer and military system requirements evolve. The broad solution space to this complex problem encompasses cooperation or codesigning of systems with both sensing and communications functions. By jointly considering the systems during the design phase, rather than perpetuating a notion of mutual interference, both system’s performance can be improved. We provide a point of departure for future researchers that will be required to solve this problem by presenting the applications, topologies, levels of system integration, the current state of the art, and outlines of future information-centric systems.

Effect of clutter on joint radar-communications system performance inner bounds

We analyze the effects of clutter on inner bounds for the performance of a joint radar-communications system. Radar returns from clutter are often characterized by a randomly fluctuating cross section. Hence, statistical methods must be employed to model the clutter and its cross-section. In this paper we consider two clutter models and analyze their effect on the inner bounds on performance of a joint radar-communications system. Bounds on performance of the joint system are measured in terms of data information rate for communications, and radar estimation information rate for the radar.

Joint radar-communications information bounds with clutter: The phase noise menace

We model the effects of phase noise on clutter cancellation and study the overall impact it has on the radar estimation rate. Cooperative bounds involving radar cancellation for additional communications access are impacted by complicating the overall model. We assume the clutter is static with small intrinsic clutter motion (ICM). Treating the clutter cancellation residual due to intrinsic clutter motion and phase noise as an additional noise source, the radar estimation rate is negatively impacted. This clutter cancellation residual further degrades the communications channel, affecting the communications data rate as well. We also study the relationship between the clutter cancellation residual and the range of the scatterer.

Radar-Communications Convergence: Coexistence, Cooperation, and Co-Design

In this paper, we introduce a radar information metric, the estimation rate, that allows the radar user to be considered in a multiple-access channel enabling performance bounds for joint radar-communications coexistence to be derived. Traditionally, the two systems were isolated in one or multiple dimensions. We categorize new attempts at spectrum-space-time convergence as either coexistence, cooperation, or co-design. The meaning and interpretation of the estimation rate and what it means to alter it are discussed. Additionally, we introduce and elaborate on the concept of “not all bits are equal,” which states that communications rate bits and estimation rate bits do not have equal value. Finally, results for joint radar-communications information bounds and their accompanying weighted spectral efficiency measures are presented.

Simultaneous radar detection and communications performance with clutter mitigation

We analyze the performance of a joint radar-communications receiver performing target detection while simultaneously decoding a message from an in-band communications user. We assume that there is clutter in the environment and that the joint receiver performs basic clutter mitigation. Inner bounds on the performance of the joint radar-communications receiver are then formulated. Bounds on performance of the joint system are measured in terms of data information rate for communications and area under the receiver operating characteristic (ROC) curve for radar.

Bridging Mixture Model Estimation and Information Bounds Using I-MMSE

We derive bounds on mutual information for arbitrary estimation problems in additive noise, modeled using Gaussian mixtures. Previous work exploiting the I-minimum-mean-squared-error (MMSE) formula to formulate a bridge between bounds on the MMSE for Gaussian mixture model estimation problems and bounds on the mutual information are generalized to allow arbitrary noise modeling. A novel upper bound on estimation information is also developed for the general estimation case. In addition, limits are analyzed to develop bounds on arbitrary entropy, asymptotic behavior of all bounds, and bound errors with some results bridged back to the MMSE domain.