177,112 research outputs found
Blind Interference Alignment for Private Information Retrieval
Blind interference alignment (BIA) refers to interference alignment schemes
that are designed only based on channel coherence pattern knowledge at the
transmitters (the "blind" transmitters do not know the exact channel values).
Private information retrieval (PIR) refers to the problem where a user
retrieves one out of K messages from N non-communicating databases (each holds
all K messages) without revealing anything about the identity of the desired
message index to any individual database. In this paper, we identify an
intriguing connection between PIR and BIA. Inspired by this connection, we
characterize the information theoretic optimal download cost of PIR, when we
have K = 2 messages and the number of databases, N, is arbitrary
Robust Private Information Retrieval on Coded Data
We consider the problem of designing PIR scheme on coded data when certain
nodes are unresponsive. We provide the construction of -robust PIR schemes
that can tolerate up to unresponsive nodes. These schemes are adaptive
and universally optimal in the sense of achieving (asymptotically) optimal
download cost for any number of unresponsive nodes up to
The capacity of symmetric Private information retrieval
Private information retrieval (PIR) is the problem of retrieving as efficiently as possible, one out of K messages from N non-communicating replicated databases (each holds all K messages) while keeping the identity of the desired message index a secret from each individual database. Symmetric PIR (SPIR) is a generalization of PIR to include the requirement that beyond the desired message, the user learns nothing about the other K - 1 messages. The information theoretic capacity of SPIR (equivalently, the reciprocal of minimum download cost) is the maximum number of bits of desired information that can be privately retrieved per bit of downloaded information. We show that the capacity of SPIR is 1-1/N regardless of the number of messages K, if the databases have access to common randomness (not available to the user) that is independent of the messages, in the amount that is at least 1/(N - 1) bits per desired message bit, and zero otherwise
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