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129
Degrees of freedom of twohop wireless networks: Everyone gets the entire cake
 IEEE Trans. Inf. Theory
, 2014
"... Abstract—We show that fully connected twohop wireless networks with K sources, K relays and K destinations have K degrees of freedom for almost all values of constant channel coefficients. Our main contribution is a new interferencealignmentbased achievability scheme which we call aligned network ..."
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Cited by 19 (1 self)
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Abstract—We show that fully connected twohop wireless networks with K sources, K relays and K destinations have K degrees of freedom for almost all values of constant channel coefficients. Our main contribution is a new interferencealignmentbased achievability scheme which we call aligned network diagonalization. This scheme allows the data streams transmitted by the sources to undergo a diagonal linear transformation from the sources to the destinations, thus being received free of interference by their intended destination. I.
Sum capacity of a class of symmetric SIMO Gaussian interference channels withinO(1
 IEEE Trans. Inf. Theory
, 2010
"... The N +1 user, 1×N single input multiple output (SIMO) Gaussian interference channel where each transmitter has a single antenna and each receiver has N antennas is studied. The symmetric capacity within O(1) is characterized for the symmetric case where all direct links have the same signaltonois ..."
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Cited by 17 (6 self)
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The N +1 user, 1×N single input multiple output (SIMO) Gaussian interference channel where each transmitter has a single antenna and each receiver has N antennas is studied. The symmetric capacity within O(1) is characterized for the symmetric case where all direct links have the same signaltonoise ratio (SNR) and all undesired links have the same interferencetonoise ratio (INR). The gap to the exact capacity is a constant which is independent of SNR and INR. To get this result, we first generalize the deterministic interference channel introduced by El Gamal and Costa in [2] to model interference channels with multiple antennas. We derive the capacity region of this deterministic interference channel. Based on the insights provided by the deterministic channel, we characterize the generalized degrees of freedom (GDOF) of Gaussian case, which directly leads to the O(1) capacity approximation. On the achievability side, an interesting conclusion is that the generalized degrees of freedom (GDOF) regime where treating interference as noise is found to be optimal in the 2 user interference channel, does not appear in the N +1 user, 1 × N SIMO case. On the converse side, new multiuser outer bounds emerge out of this work that do not follow directly from the 2 user case. In addition to the GDOF region, the outer bounds identify a strong interference regime where the capacity region is established. 2 I.
Interference Channels with Common Information
 IEEE Transactions on Information Theory
, 2008
"... Abstract—In this paper, the interference channel with common information (ICC), in which two senders need deliver not only private messages but also certain common messages to their corresponding receivers, is investigated. An achievable rate region for such a channel is obtained by applying a super ..."
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Cited by 16 (0 self)
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Abstract—In this paper, the interference channel with common information (ICC), in which two senders need deliver not only private messages but also certain common messages to their corresponding receivers, is investigated. An achievable rate region for such a channel is obtained by applying a superposition coding scheme that consists of successive encoding and simultaneous decoding. It is shown that the derived achievable rate region includes or extends several existing results for the interference channels with or without common information. The rate region is then specialized to a class of ICCs in which one sender has no private information to transmit, and a class of deterministic interference channels with common information (DICCs). In particular, the derived rate region is found to be the capacity region for this class of DICCs. Last, the achievable rate region derived for the discrete memoryless ICC is extended to the Gaussian case, in which a numerical example is provided to illustrate the improvement of our rate region over an existing result. Index Terms—Capacity region, common information, interference channel, multipleaccess channel (MAC), simultaneous decoding, superposition coding. I.
Interference Decoding for Deterministic Channels
, 2011
"... 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 interferencedecoding inner bound is ..."
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Cited by 15 (4 self)
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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 interferencedecoding inner bound is tight under certain strong interference conditions. The inner bound is also shown to strictly contain the inner bound obtained by treating interference as noise, which includes interference alignment for deterministic channels. The gain comes from judicious analysis of the number of combined interference sequences in different regimes of input distributions and message rates. Finally, the inner bound is generalized to the case where each channel output is observed through a noisy channel.
Capacity Regions and Bounds for a Class of Zinterference Channels
"... We define a class of Zinterference channels for which we obtain a new upper bound on the capacity region. The bound exploits a technique first introduced by Korner and Marton. A channel in this class has the property that, for the transmitterreceiver pair that suffers from interference, the condit ..."
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Cited by 14 (6 self)
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We define a class of Zinterference channels for which we obtain a new upper bound on the capacity region. The bound exploits a technique first introduced by Korner and Marton. A channel in this class has the property that, for the transmitterreceiver pair that suffers from interference, the conditional output entropy at the receiver is invariant with respect to the transmitted codewords. We compare the new capacity region upper bound with the Han/Kobayashi achievable rate region for interference channels. This comparison shows that our bound is tight in some cases, thereby yielding specific points on the capacity region as well as sum capacity for certain Zinterference channels. In particular, this result can be used as an alternate method to obtain sum capacity of Gaussian Zinterference channels. We then apply an additional restriction on our channel class: the transmitterreceiver pair that suffers from interference achieves its maximum output entropy with a single input distribution irrespective of the interference distribution. For these channels we show that our new capacity region upper bound coincides with the Han/Kobayashi achievable rate region, which is therefore capacityachieving. In particular, for these channels superposition encoding with partial decoding is shown to be optimal and a singleletter characterization for the capacity region is obtained.
Virtual fullduplex wireless communication via rapid onoffdivision duplex
 in Allerton Conf. on Commun., Control, and Computing
, 2010
"... Abstract—This paper introduces a novel paradigm for designing the physical and medium access control (MAC) layers of mobile ad hoc or peertopeer networks formed by halfduplex radios. A node equipped with such a radio cannot simultaneously transmit and receive useful signals at the same frequency ..."
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Cited by 12 (5 self)
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Abstract—This paper introduces a novel paradigm for designing the physical and medium access control (MAC) layers of mobile ad hoc or peertopeer networks formed by halfduplex radios. A node equipped with such a radio cannot simultaneously transmit and receive useful signals at the same frequency. Unlike in conventional designs, where a node’s transmission frames are scheduled away from its reception, each node transmits its signal through a randomly generated onoff duplex mask (or signature) over every frame interval, and receive a signal through each of its own offslots. This is called rapid onoffdivision duplex (RODD). Over the period of a single frame, every node can transmit a message to some or all of its peers, and may simultaneously receive a message from each peer. Thus RODD achieves virtual fullduplex communication using halfduplex radios and can simplify the design of higher layers of a network protocol stack significantly. The throughput of RODD is evaluated under some general settings, which is significantly larger than that of ALOHA. RODD is especially efficient in case the dominant traffic is simultaneous broadcast from nodes to their onehop peers, such as in spontaneous wireless social networks, emergency situations or on battlefield. Important design issues of peer discovery, distribution of onoff signatures, synchronization and errorcontrol coding are also addressed. Index Terms—Ad hoc network, halfduplex, multiaccess channel, neighbor discovery, random access, wireless peertopeer networks. I.
On channel output feedback in deterministic . . .
, 2009
"... In this paper, we study the effect of channel output feedback on the sum capacity in a twouser symmetric deterministic interference channel. We find that having a single feedback link from one of the receivers to its own transmitter results in the same sum capacity as having a total of 4 feedback l ..."
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Cited by 12 (2 self)
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In this paper, we study the effect of channel output feedback on the sum capacity in a twouser symmetric deterministic interference channel. We find that having a single feedback link from one of the receivers to its own transmitter results in the same sum capacity as having a total of 4 feedback links from both the receivers to both the transmitters. Hence, from the sum capacity point of view, the three additional feedback links are not helpful. We also consider a halfduplex feedback model where the forward and the feedback resources are symmetric and timeshared. Surprisingly, we find that there is no gain in sumcapacity with feedback in a halfduplex feedback model when interference links have more capacity than direct links.
Information Theoretic Games on Interference Channels
 In Proceeding of 2008 IEEE ISIT
, 2008
"... Abstract—We provide a natural formulation of information theoretic games on interference channels. We analyze this game on a class of deterministic interference channels recently introduced to approximate Gaussian channels in the interferencelimited regime. Our main result is a complete and simple c ..."
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Cited by 12 (4 self)
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Abstract—We provide a natural formulation of information theoretic games on interference channels. We analyze this game on a class of deterministic interference channels recently introduced to approximate Gaussian channels in the interferencelimited regime. Our main result is a complete and simple characterization of the subset of the interference channel capacity region that can be achieved as Nash equilibria. We show that for all parameter values of the interference channel, there are always Nash equilibria which are efficient, i.e. on the boundary of the capacity region. I.
Interference Alignment and a Noisy Interference Regime for ManytoOne Interference Channels
, 2009
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