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We consider the problem of characterizing network capacity in the presence of adversarial errors on network links, focusing in particular on the effect of low-capacity feedback links across network cuts. We give a new outer bound as well as a new achievable strategy, and show a family of networks where the inner and outer bounds coincide.
We consider the problem of minimizing the cost of cooperative data exchange between a group of wireless clients. In this problem, a group of clients needs to exchange a set of packets over a shared lossless broadcast channel. Each client initially holds a subset of packets and needs to obtain the packets held by other clients. At each round, one of the clients can broadcast its packets or a combination...
Recent works on multi-user transmission techniques have shown that the linear growth of capacity in single user MIMO system can be translated to the multi-user MIMO scenario as well. In this paper, we propose a method pursuing performance gain of vector perturbation in multi-user downlink channels. Instead of exploiting the maximum available mobile users for communication, we employ small part of...
We consider a discrete memoryless channel between two users and a destination in half-duplex mode implemented by time division. Each transmission block of length n is divided into 3 time slots with variable durations. During the first two time slots, each user alternatively transmits and receives, while during the last time slot, they both transmit to the destination. Even though within each time...
In this work, we study the effects of finite buffers on the throughput and delay of line networks with erasure links. We identify the calculation of performance parameters such as throughput and delay to be equivalent to determining the stationary distribution of an irreducible Markov chain. We note that the number of states in the Markov chain grows exponentially in the size of the buffers with the...
In this paper, we study the effect of a single link on the capacity of a network of error-free bit pipes. More precisely, we study the change in network capacity that results when we remove a single link of capacity δ. In a recent result, we proved that if all the sources are directly available to a single super-source node, then removing a link of capacity δ cannot change the capacity region of the...
The problem of compressing a real-valued sparse source using compressive sensing techniques is studied. The rate distortion optimality of a coding scheme in which compressively sensed signals are quantized and then reconstructed is established when the reconstruction is also required to be sparse. The result holds in general when the distortion constraint is on the expected p-norm of error between...
Link failures in wide area networks are common. To recover from such failures, a number of methods such as SONET rings, protection cycles, and source rerouting have been investigated. Two important considerations in such approaches are the recovery time and the needed spare capacity to complete the recovery. Usually, these techniques attempt to achieve a recovery time less than 50 ms. In this paper...
We consider two-hop S-R-D Gaussian networks with a source (S), a relay (R) and a destination (D), some of which experience additive interference. This additive interference, which renders the channels state-dependent, is either a) experienced at the destination D and known non-causally at the source S, or b) experienced at the relay R and known at the destination D. In both cases, one would hope to...
In this paper, we analyze the performance of a peer-to-peer (P2P) distributed storage architecture based on a layered overlay scheme, where some nodes provide their disk capacities for hosting data fragments generated by other active users. This system has been introduced and studied, by means of simulations, in a previous paper, where the use of randomized network coding has been proposed as an appealing...
Causal video coding is a coding paradigm where video source frames X1, X2, ..., XN are encoded in a frame by frame manner, the encoder for each frame can use all previous frames and all previous encoded frames, and the corresponding decoder can use only all previous encoded frames. In the special case where the encoder for each frame Xk is further restricted to enlist help only from all previous encoded...
We consider a class of distributed algorithms for computing arithmetic averages (average consensus) over networks of agents connected through digital noisy broadcast channels. Our algorithms combine error-correcting codes with the classical linear consensus iterative algorithm, and do not require the agents to have knowledge of the global network structure. We improve the performance by introducing...
This paper addresses coding for power transfer, modulation, and error control for the reader-to-tag channel in near-field passive radio frequency identification (RFID) systems using inductive coupling as a power transfer mechanism. Different assumptions on channel noise (including two different models for bit-shifts, insertions and deletions, and additive white Gaussian noise) are discussed. In particular,...
We consider a two-way relay channel (TRC) in which two terminals exchange their messages with the help of a relay between them. The two terminals transmit messages to the relay through the Multiple Access Channel (MAC) and the relay transmits messages to the two terminals through the Broadcast Channel (BC). We assume that the MAC and the BC do not interfere with each other, and each terminal receives...
The partition function contains valuable information about a graphical model. Unfortunately, the exact partition function is very often intractable, and so suitable approximations are desirable, two of them being the (fractional) Bethe approximation and the (fractional) Kikuchi approximation. We present combinatorial characterizations of these partition function approximations based on counting valid...
A new coding scheme for image transmission over noisy channel is proposed. Similar to standard image compression, the scheme includes a linear transform followed by embedded scalar quantization. Joint source-channel coding is implemented by optimizing the rate allocation across the source subbands, treated as the components of a parallel source model. The quantized transform coefficients are linearly...
Flash memory is a non-volatile computer storage device which consists of blocks of cells. While increasing the voltage level of a single cell is fast and simple, reducing the level of a cell requires the erasing of the entire block containing the cell. Since block-erasures are costly, traditional flash coding schemes have been developed to maximize the number of writes before a block-erasure is needed...
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