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- Viveck R. Cadambe, Syed Ali Jafar
- IEEE Trans. Information Theory
- 2008

For the fully connected K user wireless interference channel where the channel coefficients are time-varying and are drawn from a continuous distribution, the sum capacity is characterized as C(SNR) = K 2 log(SNR) + o(log(SNR)). Thus, the K user time-varying interference channel almost surely has K=2 degrees of freedom. Achievability is based on the idea of… (More)

- Krishna Srikanth Gomadam, Viveck R. Cadambe, Syed Ali Jafar
- GLOBECOM
- 2008

Recent results establish the optimality of interference alignment to approach the Shannon capacity of interference networks at high SNR. However, the extent to which interference can be aligned over a finite number of signalling dimensions remains unknown. Another important concern for interference alignment schemes is the requirement of global channel… (More)

- Krishna Srikanth Gomadam, Viveck R. Cadambe, Syed Ali Jafar
- IEEE Transactions on Information Theory
- 2011

Recent results establish the optimality of interference alignment to approach the Shannon capacity of interference networks at high SNR. However, the extent to which interference can be aligned over a finite number of signalling dimensions remains unknown. Another important concern for interference alignment schemes is the requirement of global channel… (More)

- Viveck R. Cadambe, Syed Ali Jafar
- IEEE Trans. Information Theory
- 2009

We explore the degrees of freedom of M ×N user wireless X networks, i.e. networks of M transmitters and N receivers where every transmitter has an independent message for every receiver. We derive a general outerbound on the degrees of freedom region of these networks. When all nodes have a single antenna and all channel coefficients vary in time or… (More)

- Viveck R. Cadambe, Syed Ali Jafar
- ArXiv
- 2007

While the best known outerbound for the K user interference channel states that there cannot be more than K/2 degrees of freedom, it has been conjectured that in general the constant interference channel with any number of users has only one degree of freedom. In this paper, we explore the spatial degrees of freedom per orthogonal time and frequency… (More)

- Viveck R. Cadambe, Syed Ali Jafar
- IEEE Transactions on Information Theory
- 2009

We find the degrees of freedom of a network with S source nodes, <i>R</i> relay nodes, and D destination nodes, with random time-varying/frequency-selective channel coefficients and global channel knowledge at all nodes. We allow full-duplex operation at all nodes, as well as causal noise-free feedback of all received signals to all source and relay nodes.… (More)

- Syed A. Jafar, Viveck Cadambe, Chenwei Wang
- 2009 47th Annual Allerton Conference on…
- 2009

It has been conjectured that complex Gaussian interference channels with constant channel coefficients have only one degree-of-freedom (DoF) regardless of the number of users. While several examples are known of constant channels that achieve more than 1 DoF, these special cases only span a subset of measure zero. In other words, for almost all channel… (More)

- Viveck R. Cadambe, Syed Ali Jafar
- ICC
- 2008

We show that the sum capacity of the K user frequency selective (or time-varying) interference channel is C(SNR) = (K/2) log(SNR)+o(log(SNR)) meaning that the channel has a total of K/2 degrees of freedom per orthogonal time and frequency dimension. Linear schemes of interference alignment and zero forcing suffice to achieve all the degrees of freedom and… (More)

- Hamed Maleki, Viveck R. Cadambe, Syed Ali Jafar
- 2012 IEEE International Symposium on Information…
- 2012

The index coding problem is a multiple unicast wireline communication network where the network is represented by a directed graph having exactly one link with finite capacity (also known as the bottleneck link). There are K independent sources which share the ingress of this bottleneck link. Correspondingly there are K destinations which are on the… (More)

- Viveck R. Cadambe, Syed Ali Jafar, Hamed Maleki, Kannan Ramchandran, Changho Suh
- IEEE Transactions on Information Theory
- 2013

The high repair bandwidth cost of (<i>n</i>,<i>k</i>) maximum distance separable (MDS) erasure codes has motivated a new class of codes that can reduce repair bandwidth over that of conventional MDS codes. In this paper, we address (<i>n</i>,<i>k</i>,<i>d</i>) exact repair MDS codes, which allow for any single failed node to be repaired exactly with access… (More)