Abbas El Gamal

• Stanford University

We propose a GPU accelerated proximal message passing algorithm for solving contingency-constrained DC optimal power flow problems (OPF). We consider a highly general formulation of OPF that uses a sparse device-node model and supports a broad range of devices and constraints, e.g., energy storage and ramping limits. Our algorithm is a variant of t...

We propose a GPU accelerated proximal message passing algorithm for solving contingency-constrained DC optimal power flow problems (OPF). We consider a highly general formulation of OPF that uses a sparse device-node model and supports a broad range of devices and constraints, e.g., energy storage and ramping limits. Our algorithm is a variant of t...

Large scale grid expansion planning studies are essential to rapidly and efficiently decarbonizing the electricity sector. These studies help policy makers and grid participants understand which renewable generation, storage, and transmission assets should be built and where they will be most cost effective or have the highest emissions impact. How...

Marginal emissions rates -- the sensitivity of carbon emissions to electricity demand -- are important for evaluating the impact of emissions mitigation measures. Like locational marginal prices, locational marginal emissions rates (LMEs) can vary geographically, even between nearby locations, and may be coupled across time periods because of, for...

A previous study has shown that coordinating DERs to protect the distribution grid can significantly reduce the infrastructure upgrades needed to address future increases in DER and electrification penetrations. Implementing such coordination in the real world, however, is challenging due the temporal and spatial uncertainties about the loads and r...

Current DER coordination schemes, such as demand-response and VPPs, aim to reduce electricity costs during peak demand events with no consideration of distribution grid reliability. We show that coordinating DERs for grid reliability can significantly reduce both the infrastructure upgrades needed to support future increases in DER and electrificat...

Locational marginal emissions rates (LMEs) estimate the rate of change in emissions due to a small change in demand in a transmission network, and are an important metric for assessing the impact of various energy policies or interventions. In this work, we develop a new method for computing the LMEs of an electricity system via implicit differenti...

This article highlights some of Katalin Marton's main contributions to rate distortion theory, probability theory, and multiuser information theory and their lasting impact on the work of many other researchers.

Locational marginal emissions rates (LMEs) estimate the rate of change in emissions due to a small change in demand in a transmission network, and are an important metric for assessing the impact of various energy policies or interventions. In this work, we develop a new method for computing the LMEs of an electricity system via implicit differenti...

We develop a new upper bound on the capacity of the relay channel that is tighter than previously known upper bounds. This upper bound is proved using traditional weak converse techniques involving mutual information inequalities and Gallager-type explicit identification of auxiliary random variables. We show that the new upper bound is strictly ti...

We establish new upper bounds on the capacity of the relay channel which are tighter than all previous bounds. The upper bounds use traditional weak converse techniques involving mutual information inequalities and identification of auxiliary random variables via past and future channel random variable sequences. For the relay channel without self-...

The classical problem of supervised learning is to infer an accurate estimate of a target variable $Y$ from a measured variable $X$ using a set of labeled training samples. Motivated by the increasingly distributed nature of data and decision making, this paper considers a variation of this classical problem in which the inference is distribute...

Reliability and voltage quality in distribution networks have been achieved via a combination of transformer power rating satisfaction and voltage management asset control. To maintain reliable operation under this paradigm, however, future grids with deep DER penetrations would require costly equipment upgrades. These upgrades can be mitigated via...

This paper presents a two-layer distributed energy resource (DER) coordination architecture that allows for separate ownership of data, operates with data subjected to a large buffering delay, and employs a new measure of power quality. The two-layer architecture comprises a centralized model predictive controller (MPC) and several decentralized MP...

The classical problem of supervised learning is to infer an accurate predictor of a target variable $Y$ from a measured variable $X$ by using a finite number of labeled training samples. Motivated by the increasingly distributed nature of data and decision making, in this paper we consider a variation of this classical problem in which the predicti...

This paper shows that the Hirschfeld-Gebelein-Rényi maximal correlation between the message and the ciphertext provides good secrecy guarantees for cryptosystems that use short keys. We first establish a bound on the eavesdropper’s advantage in guessing functions of the message in terms of maximal correlation and the Rényi entropy of the message. T...

Alice selects an arbitrary pdf f and uses a stochastic encoder to generate a prefix-free codeword M, which is sent to Bob so that he can generate a single instance of the random variable X ~ f. We describe a universal coding scheme for this setup which works for any f, and establish an upper bound on its expected codeword length when the pdf f is b...

We establish the rate region of an extended Gray– Wyner system (EGW) for 2-DMS (X, Y ) with two additional decoders having complementary causal side information. We show that the 5-dimensional rate region of the EGW system is equivalent to the 3-dimensional mutual information region consisting of the set of all triples of the form (I(X; U),I(Y; U),...

We consider the problem of controlling distributed storage in a distribution network with renewable distributed generation to minimize network operational cost while satisfying power quality constraints. We assume control is distributed between a global controller (GC) and local controllers (LC) located at the nodes with storage units. Each LC has...

We establish the first known upper bound on the exact and Wyner’s common information of n continuous random variables in terms of the dual total correlation between them (which is a generalization of mutual information). In particular, we show that when the pdf of the random variables is logconcave, there is a constant gap of n² log e + 9n log n be...

We develop a methodology for maximizing the present value of an independently operated electric energy storage (EES) unit co-optimized to perform both energy arbitrage (EA) and regulation service (RS). While our methodology applies to all types of EES, it is particularly suitable for EES units with a finite cycle life and a high power-to-capacity r...

We establish the rate region of an extended Gray-Wyner system for 2-DMS $(X,Y)$ with two additional decoders having complementary causal side information. This extension is interesting because in addition to the operationally significant extreme points of the Gray-Wyner rate region, which include Wyner's common information, G{\'a}cs-K{\"o}rner comm...

This paper shows that for any random variables $X$ and $Y$, it is possible to represent $Y$ as a function of $(X,Z)$ such that $Z$ is independent of $X$ and $I(X;Z|Y)\le\log(I(X;Y)+1)+4$. We use this strong functional representation lemma (SFRL) to establish a tighter bound on the rate needed for one-shot exact channel simulation than was previousl...

We propose Powernet as an end-to-end open source technology for economically efficient, scalable and secure coordination of grid resources. It offers integrated hardware and software solutions that are judiciously divided between local embedded sensing, computing and control, which are networked with cloud-based high-level coordination for real-tim...

We consider a setup in which Alice selects a pdf $f$ from a set of prescribed pdfs $\mathscr{P}$ and sends a prefix-free codeword $W$ to Bob in order to allow him to generate a single instance of the random variable $X\sim f$. We describe a universal coding scheme for this setup and establish an upper bound on the expected codeword length when the...

We establish the first known upper bound on the exact and Wyner's common information of $n$ continuous random variables in terms of the dual total correlation between them (which is a generalization of mutual information). In particular, we show that when the pdf of the random variables is log-concave, there is a constant gap of $n^{2}\log e+9n\log...

Designing fair compensation mechanisms for demand response (DR) is challenging. This paper models the problem in a game theoretic setting and designs a payment distribution mechanism based on the Shapley value (SV). As exact computation of the SV is in general intractable, we propose estimating it using a reinforcement learning algorithm that appro...

We establish the capacity region of several classes of broadcast channels with random state in which the channel to each user is selected from two possible channel state components and the state is known only at the receivers. When the channel components are deterministic, we show that the capacity region is achieved via Marton coding. This channel...

This paper shows that the capacity region of the continuous-time Poisson broadcast channel is achieved via superposition coding for most channel parameter values. Interestingly, the channel in some subset of these parameter values does not belong to any of the existing classes of broadcast channels for which superposition coding is optimal (e.g., d...

This paper shows that the Hirschfeld-Gebelein-R\'enyi maximal correlation between the message and the ciphertext provides good secrecy guarantees for ciphers that use short keys. We show that a maximal correlation $0< \rho < 1$ can be achieved via a randomly generated cipher with key length of around $2 \log(1/\rho)$ for small $\rho$, independent o...

Consider a Gaussian relay network where a source node communicates to a destination node with the help of several layers of relays. Recent work has shown that compress-and-forward based strategies can achieve the capacity of this network within an additive gap. Here, the relays quantize their received signals at the noise level and map them to rand...

Coordinated multipoint (CoMP) transmission is an infrastructural enhancement under consideration for next generation wireless networks. In this paper, the capacity gain achieved through CoMP transmission is studied in various models of wireless networks that have practical significance. The capacity gain is analyzed through the degrees of freedom (...

Designing fair compensation mechanisms for demand response (DR) is challenging. This paper models the problem in a game theoretic setting and designs a payment distribution mechanism based on the Shapley Value. As exact computation of the Shapley Value is in general intractable, we propose estimating it using a reinforcement learning algorithm that...

This paper introduces the notion of exact common information, which is the minimum description length of the common randomness needed for the exact distributed generation of two correlated random variables $(X,Y)$. We introduce the quantity $G(X;Y)=\min_{X\to W \to Y} H(W)$ as a natural bound on the exact common information and study its properties...

In this paper, we provide an improved lower bound on the rate achieved by noisy network coding in arbitrary Gaussian relay networks, whose gap to the cutset upper bound depends on the network not only through the total number of nodes but also through the degrees of freedom of the min cut of the network. We illustrate that for many networks this re...

This paper establishes the capacity region of a class of broadcast channels with random state in which each channel component is selected from two possible functions and each receiver knows its state sequence. This channel model does not fit into any class of broadcast channels for which the capacity region was previously known and is useful in stu...

Existing feedback communication schemes are either specialized to particular channels (Schalkwijk--Kailath, Horstein), or apply to general channels but have high coding complexity (block feedback schemes) or are difficult to analyze (posterior matching). This paper introduces a feedback coding scheme that combines features from previous schemes in...

The high variability of renewable energy is a major obstacle toward its increased penetration. Energy storage can help reduce the power imbalance due to the mismatch between the available renewable power and the load. How much can storage reduce this power imbalance? How much storage is needed to achieve this reduction? This paper presents a simple...

This paper shows that the Ali-Tse scheme which establishes the symmetric capacity of two example broadcast channels with strictly causal state information at the transmitter is a simple special case of the Shayevitz-Wigger scheme for the broadcast channel with generalized feedback, which involves block Markov coding, compression, superposition codi...

This paper considers the problem of communicating over a relay channel with state when noncausal state information is partially available at the nodes. We first establish a lower bound on the achievable rates based on noisy network coding and Gelfand-Pinsker coding, and show that it provides an alternative characterization of a previously known bou...

GridSpice is a simulation framework for the smart grid that integrates existing electric power point tools. The framework provides computational scale and modeling capability to represent diverse scenarios in large interconnected grid systems. Currently, GridSpice integrates a transmission and economic dispatch package based on MatPOWER and the dis...

This article describes a sensor network approach to tracking a single object in the presence of static and moving occluders using a network of cameras. To conserve communication bandwidth and energy, we combine a task-driven approach with camera subset selection. In the task-driven approach, each camera first performs simple local processing to det...

Using Ca(2+) imaging in freely behaving mice that repeatedly explored a familiar environment, we tracked thousands of CA1 pyramidal cells' place fields over weeks. Place coding was dynamic, as each day the ensemble representation of this environment involved a unique subset of cells. However, cells in the ∼15-25% overlap between any two of these su...

Supplementary Figure 1 Ca2+ dynamics of CA1 pyramidal cells visualized during active mouse behavior. Supplementary Figure 2 Fluorescence imaging with the integrated microscope caused no photobleaching or evident deterioration in neuronal health. Supplementary Figure 3 Image registration had 1-µm accuracy and enabled identification of the same CA1 n...

Demand Response, or adjusting the aggregate load profile as a means to help balance supply and demand in electricity grids, is currently a popular area of research. In this paper, we propose analyzing demand response schemes in a game theoretic setting, and utilizing the Shapley Value for fairly compensating participants of such schemes. As exact c...

A CMOS image sensor architecture with built-in single-shot compressed sensing is described. The image sensor employs a conventional 4-T pixel and per-column ΣΔ ADCs. The compressed sensing measurements are obtained via a column multiplexer that sequentially applies randomly selected pixel values to the input of each ΣΔ modulator. At the end of read...

The optimal rate region for interference networks is characterized when encoding is restricted to random code ensembles with superposition coding and time sharing. A simple simultaneous nonunique decoding rule, under which each receiver decodes for the intended message as well as the interfering messages, is shown to achieve this optimal rate regio...

It is shown that simultaneous nonunique decoding is rate-optimal for the general K-sender, L-receiver discrete memoryless interference channel when encoding is restricted to randomly generated codebooks, superposition coding, and time sharing. This result implies that the Han-Kobayashi inner bound for the two-user-pair interference channel cannot b...

The paper investigates the effect of link delay on the capacity region of the interference channel with strong interference. It is shown that the capacity region of the strong interference channel with unit delay on one of the cross links (SICD) is at least as large as that without delay. This is established by obtaining a "multi-letter" characteri...

This paper establishes inner bounds on the secrecy capacity regions for the general three-receiver broadcast channel with one common and one confidential message sets. We consider two setups. The first is when the confidential message is to be sent to two receivers and kept secret from the third receiver. Achievability is established using indirect...

SRAM based configuration memory is the primary contributor to the large area, delay, and power consumption of FPGAs relative to ASICs. In [1] it is estimated that a 3D-FPGA with the configuration memory stacked on top of the FPGA logic and routing can achieve 57% smaller die area than a baseline 2D-FPGA in 65nm CMOS technology. Motivated by these p...

Low power consumption is a primary concern in many CMOS image-sensor applications. As the resolution of these sensors has increased while maintaining or increasing their frame rates, A/D conversion has become the dominant component of power consumption [1]. Conventional image compression can help reduce the readout rate [2] (and hence its power con...

This comprehensive treatment of network information theory and its applications provides the first unified coverage of both classical and recent results. With an approach that balances the introduction of new models and new coding techniques, readers are guided through Shannon's point-to-point information theory, single-hop networks, multi-hop netw...

The high variability of renewable energy resources presents significant challenges to the operation of the electric power grid. Conventional generators can be used to mitigate this variability but are costly to operate and produce carbon emissions. Energy storage provides a more environmentally friendly alternative, but is costly to deploy in large...

Supplementary Figure 1: An array of integrated microscopes can facilitate parallel imaging applications. Supplementary Figure 2: The integrated microscope enables Ca2+ imaging studies of CA1 hippocampal pyramidal neurons in freely behaving mice. Supplementary Table 1: CMOS image sensor specifications and characterization results Supplementary Video...

The light microscope is traditionally an instrument of substantial size and expense. Its miniaturized integration would enable many new applications based on mass-producible, tiny microscopes. Key prospective usages include brain imaging in behaving animals for relating cellular dynamics to animal behavior. Here we introduce a miniature (1.9 g) int...

This paper presents a new coding scheme and a corresponding achievable rate region for a class of deterministic interference channels with three sender-receiver pairs (3-DIC). The codebook structure uses rate splitting, Marton coding, and superposition coding. The receivers use interference decoding to exploit the structure of the combined interfer...

The large short time-scale variability of renewable energy resources presents significant challenges to the reliable operation of power systems. This variability can be mitigated by deploying fast-ramping generators. However, these generators are costly to operate and produce environmentally harmful emissions. Fast-response energy storage devices,...

A noisy network coding scheme for communicating messages between multiple sources and destinations over a general noisy network is presented. For multi-message multicast networks, the scheme naturally generalizes network coding over noiseless networks by Ahlswede, Cai, Li, and Yeung, and compress-forward coding for the relay channel by Cover and El...

Motivated by the broadcast view of the interference channel, the new problem of communication with disturbance constraints is formulated. The rate-disturbance region is established for the single constraint case and the optimal encoding scheme turns out to be the same as the Han-Kobayashi scheme for the two user-pair interference channel. This resu...

The paper establishes the capacity region of the Gaussian interference channel with many transmitter-receiver pairs constrained to use point-to-point codes. The capacity region is shown to be strictly larger in general than the achievable rate regions when treating interference as noise, using successive interference cancellation decoding, and usin...

This paper proposes a systematic strategy to efficiently explore the design space of field-programmable gate array (FPGA) routing architectures. The key idea is to use stochastic methods to quickly locate near-optimal solutions in designing FPGA routing architectures without exhaustively enumerating all design points. The main objective of this pap...

In this paper, an information theoretic formulation of the distributed averaging problem previously studied in computer science and control is presented. We assume a network with m nodes each observing a white Gaussian noise (WGN) source. The nodes communicate and perform local processing with the goal of computing the average of the sources to wit...

Noisy network coding naturally combines two parallel lines of work on network information flow --- network coding over noiseless networks by Ahlswede, Cai, Li, and Yeung, and compress--forward coding for the relay channel by Cover and El Gamal and extends both results to general discrete memoryless and Gaussian networks. In particular, it achieves...

An inner bound to the capacity region of a class of three user pair deterministic interference channels is presented. The key idea is to simultaneously decode the combined interference signal and the intended message at each receiver. It is shown that this interference-decoding inner bound strictly contains the inner bound obtained by treating inte...

Noisy network coding unifies network coding by Ahlswede, Cai, Li, and Yeung for noiseless networks and compress-forward by Cover and El Gamal for noisy relay channels. In particular, it achieves the best known capacity inner bounds for multi-source multicast networks including deterministic networks by Avestimehr, Diggavi, and Tse and erasure netwo...

A lower bound on the secrecy capacity of the wiretap channel with state information available causally at both the encoder and decoder is established. The lower bound is shown to be strictly larger than that for the noncausal case by Liu and Chen. Achievability is proved using block Markov coding, Shannon strategy, and key generation from common st...

We establish several new results on Marton's coding scheme and its corresponding inner bound on the capacity region of the general broadcast channel. We show that unlike the Gaussian case, Marton's coding scheme without superposition coding is not optimal in general even for a degraded broadcast channel with no common message. We then establish pro...

In this paper, we study the Nair-El Gamal outer bound and Marton's inner bound for general two-receiver broadcast channels. We show that the Nair-El Gamal outer bound can be made fully computable. For the inner bound, we show that, unlike in the Gaussian case, for a degraded broadcast channel even without a common message, Marton's coding scheme wi...

A 3-node lossy source coding problem for a 2-DMS (X1, X2) is considered. Source nodes 1 and 2 observe X1 and X2, respectively, and each wishes to reconstruct the other source with a prescribed distortion. To achieve these goals, nodes 1 and 2 send descriptions of their sources to relay node 3. The relay node then broadcasts a joint description to t...

A new achievability scheme for the compound channel with discrete memoryless (DM) state noncausally available at the encoder is established. Achievability is proved using superposition coding, Marton coding, joint typicality encoding, and indirect decoding. The scheme is shown to achieve strictly higher rate than the straightforward extension of th...

A new coding scheme for multicasting multiple sources over a general noisy network is presented. The scheme naturally extends both network coding over noiseless networks by Ahlswede, Cai, Li, and Yeung, and compress-forward coding for the relay channel by Cover-El Gamal to general discrete memoryless and Gaussian networks. The scheme also recovers...

An inner bound to the capacity region of a class of deterministic interference channels with three user pairs is presented. The key idea is to simultaneously decode the combined interference signal and the intended message at each receiver. It is shown that this interference-decoding inner bound is tight under certain strong interference conditions...

These lecture notes have been converted to a book titled Network Information Theory published recently by Cambridge University Press. This book provides a significantly expanded exposition of the material in the lecture notes as well as problems and bibliographic notes at the end of each chapter. The authors are currently preparing a set of slides...

This paper presents an information theoretic source coding formulation of distributed averaging. We assume a network with m nodes each observing an i.i.d. Gaussian source; the nodes communicate and perform local processing with the goal of computing the average of the sources to within a prescribed mean squared error distortion. A general cutset lo...

A lower bound on the secrecy capacity of the wiretap channel with state information available causally at both the encoder and decoder is established. The lower bound is shown to be strictly larger than that for the noncausal case by Liu and Chen. Achievability is proved using block Markov coding, Shannon strategy, and key generation from common st...

This paper describes a new programmable routing fabric for field-programmable gate arrays (FPGAs). Our results show that an FPGA using this fabric can achieve 1.57 times lower dynamic power consumption and 1.35 times lower average net delays with only 9% reduction in logic density over a baseline island-style FPGA implemented in the same 65-nm CMOS...

Korner and Marton established the capacity region for the two-receiver broadcast channel with degraded message sets. Recent results and conjectures suggest that a straightforward extension of the Korner-Marton region to more than two receivers is optimal. This paper shows that this is not the case. We establish the capacity region for a class of th...

This paper illustrates the performance advantages of 3D integrated circuits with two specific examples, namely 3D-FPGA and 3D-SRAM. Through strategic modification of the architectures to take advantage of 3D, significant improvement in speed and reduction in power consumption can be achieved.

This paper establishes inner bounds on the secrecy capacity regions for the general 3-receiver broadcast channel with one common and one confidential message sets. We consider two setups. The first is when the confidential message is to be sent to two receivers and kept secret from the third receiver. Achievability is established using indirect dec...

Achievable secrecy rate regions for the general 3-receiver broadcast channel with one common and one confidential message sets are established. We consider two setups: (i) when the confidential message is to be sent to two of the receivers and the third receiver is an eavesdropper; and (ii) when the confidential message is to be sent to one of the...

Certain deterministic interference channels have been shown to accurately model Gaussian interference channels in the asymptotic low-noise regime. Motivated by this correspondence, we investigate a K user-pair, cyclically symmetric, deterministic interference channel in which each receiver experiences interference only from its neighboring transmit...

We investigate distributed source coding of two correlated sources X and Y where messages are passed to a decoder in a cascade fashion. The encoder of X sends a message at rate R₁ to the encoder of Y. The encoder of Y then sends a message to the decoder at rate R₂ based both on Y and on the message it received about X. The dec...