67 research outputs found
Differentially Private State Estimation in Distribution Networks with Smart Meters
State estimation is routinely being performed in high-voltage power
transmission grids in order to assist in operation and to detect faulty
equipment. In low- and medium-voltage power distribution grids, on the other
hand, few real-time measurements are traditionally available, and operation is
often conducted based on predicted and historical data. Today, in many parts of
the world, smart meters have been deployed at many customers, and their
measurements could in principle be shared with the operators in real time to
enable improved state estimation. However, customers may feel reluctance in
doing so due to privacy concerns. We therefore propose state estimation schemes
for a distribution grid model, which ensure differential privacy to the
customers. In particular, the state estimation schemes optimize different
performance criteria, and a trade-off between a lower bound on the estimation
performance versus the customers' differential privacy is derived. The proposed
framework is general enough to be applicable also to other distribution
networks, such as water and gas networks
Communication and Interference Coordination
We study the problem of controlling the interference created to an external
observer by a communication processes. We model the interference in terms of
its type (empirical distribution), and we analyze the consequences of placing
constraints on the admissible type. Considering a single interfering link, we
characterize the communication-interference capacity region. Then, we look at a
scenario where the interference is jointly created by two users allowed to
coordinate their actions prior to transmission. In this case, the trade-off
involves communication and interference as well as coordination. We establish
an achievable communication-interference region and show that efficiency is
significantly improved by coordination
Finding Cures for Tropical Diseases: Is Open Source an Answer?
We construct polar codes for binary relay channels with orthogonal receiver components. We show that polar codes achieve the cut-set bound when the channels are symmetric and the relay-destination link supports compress-and-forward relaying based on Slepian-Wolf coding. More generally, we show that a particular version of the compress-and-forward rate is achievable using polar codes for Wyner-Ziv coding. In both cases the block error probability can be bounded as O(2-Nβ) for 0 < β < 1/2 and sufficiently large block length N.Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. QC 20111207</p
Performance Analysis and Design of Two Edge Type LDPC Codes for the BEC Wiretap Channel
We consider transmission over a wiretap channel where both the main channel
and the wiretapper's channel are Binary Erasure Channels (BEC). We propose a
code construction method using two edge type LDPC codes based on the coset
encoding scheme. Using a standard LDPC ensemble with a given threshold over the
BEC, we give a construction for a two edge type LDPC ensemble with the same
threshold. If the given standard LDPC ensemble has degree two variable nodes,
our construction gives rise to degree one variable nodes in the code used over
the main channel. This results in zero threshold over the main channel. In
order to circumvent this problem, we numerically optimize the degree
distribution of the two edge type LDPC ensemble. We find that the resulting
ensembles are able to perform close to the boundary of the rate-equivocation
region of the wiretap channel.
There are two performance criteria for a coding scheme used over a wiretap
channel: reliability and secrecy. The reliability measure corresponds to the
probability of decoding error for the intended receiver. This can be easily
measured using density evolution recursion. However, it is more challenging to
characterize secrecy, corresponding to the equivocation of the message for the
wiretapper. M\'easson, Montanari, and Urbanke have shown how the equivocation
can be measured for a broad range of standard LDPC ensembles for transmission
over the BEC under the point-to-point setup. By generalizing the method of
M\'easson, Montanari, and Urbanke to two edge type LDPC ensembles, we show how
the equivocation for the wiretapper can be computed. We find that relatively
simple constructions give very good secrecy performance and are close to the
secrecy capacity. However finding explicit sequences of two edge type LDPC
ensembles which achieve secrecy capacity is a more difficult problem. We pose
it as an interesting open problem.Comment: submitted to IEEE Transactions on Information Theory. Updated versio
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