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A ratesplitting approach to the Gaussian multipleaccess channel
 IEEE TRANS. INFORM. THEORY
, 1996
"... It is shown that any point in the capacity region of a Gaussian multipleaccess channel is achievable by singleuser coding without requiring synchronization among users, provided that each user “splits” data and signal into two parts. Based on this result, a new multipleaccess technique called rat ..."
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Cited by 130 (2 self)
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It is shown that any point in the capacity region of a Gaussian multipleaccess channel is achievable by singleuser coding without requiring synchronization among users, provided that each user “splits” data and signal into two parts. Based on this result, a new multipleaccess technique called ratesplitting multiple accessing (RSMA) is proposed. RSMA is a codedivision multipleaccess scheme for the Muser Gaussian multipleaccess channel for which the effort of finding the codes for the M users, of encoding, and of decoding is that of at most 2M  1 independent pointtopoint Gaussian channels. The effects of bursty sources, multipath fading, and intercell interference are discussed and directions for further research are indicated.
Universal Bound on the Performance of Lattice Codes
 IEEE TRANS. INFORM. THEORY
, 1999
"... We present a lower bound on the probability of symbol error for maximumlikelihood decoding of lattices and lattice codes on a Gaussian channel. The bound is tight for error probabilities and signaltonoise ratios of practical interest, as opposed to most existing bounds that become tight asymptoti ..."
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Cited by 26 (0 self)
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We present a lower bound on the probability of symbol error for maximumlikelihood decoding of lattices and lattice codes on a Gaussian channel. The bound is tight for error probabilities and signaltonoise ratios of practical interest, as opposed to most existing bounds that become tight asymptotically for high signaltonoise ratios. The bound is also universal; it provides a limit on the highest possible coding gain that may be achieved, at specific symbol error probabilities, using any lattice or lattice code in n dimensions. In particular, it is shown that the effective coding gains of the densest known lattices are much lower than their nominal coding gains. The asymptotic (as n !1) behavior of the new bound is shown to coincide with the Shannon limit for Gaussian channels.
Multidimensional Multilevel Coding for Satellite Broadcasting with Highly Flexible QoS
"... Abstract—We introduce the use of multidimensional (MD) constellations in a multilevel coding (MLC) scheme with multi– stage decoding (MSD) designed for broadcasting communications, where services with different quality of service (QoS) are desirable. We show that the number of different protection l ..."
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Cited by 2 (2 self)
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Abstract—We introduce the use of multidimensional (MD) constellations in a multilevel coding (MLC) scheme with multi– stage decoding (MSD) designed for broadcasting communications, where services with different quality of service (QoS) are desirable. We show that the number of different protection levels increases when using MD constellations. Besides, the appropriate block labeling (BL) partitioning for an MD constellation is found by applying the binary switching algorithm (BSA) as an efficient search algorithm. Two cost functions for the BSA are proposed based on the BL criterion. Some methods to construct an appropriate MD constellation are presented, including the use of uniform and non–uniform component constellations. The viability of the proposed MD constellations approach for broadcasting with different protection levels is evaluated analyzing the mutual information (MI) of each level. Finally, we present a comparison between a unidimensional and a multidimensional scheme which again demonstrates the benefits of the proposed scheme. I.
On the TwoUser Interference Channel With Lack of Knowledge of the Interference Codebook at One Receiver
"... Abstract — In multiuser information theory, it is often assumed that every node in the network possesses all codebooks used in the network. This assumption may be impractical in distributed ad hoc, cognitive, or heterogeneous networks. This paper considers the twouser interference channel with one ..."
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Abstract — In multiuser information theory, it is often assumed that every node in the network possesses all codebooks used in the network. This assumption may be impractical in distributed ad hoc, cognitive, or heterogeneous networks. This paper considers the twouser interference channel with one oblivious receiver (ICOR), i.e., one receiver lacks knowledge of the interfering cookbook, whereas the other receiver knows both codebooks. This paper asks whether, and if so how much, the channel capacity of the ICOR is reduced compared with that of the classical IC where both receivers know all codebooks. A novel outer bound is derived and shown to be achievable to within a gap for the class of injective semideterministic ICORs; the gap is shown to be zero for injective fully deterministic ICORs. An exact capacity result is shown for the general memoryless ICOR when the nonoblivious receiver experiences very strong interference. For the linear deterministic ICOR that models the Gaussian noise channel at high SNR, nonindependent identically distributed. Bernoulli(1/2) input bits are shown to achieve points not achievable by i.i.d. Bernoulli(1/2) input bits used in the same achievability scheme. For the realvalued Gaussian ICOR, the gap is shown to be at most 1/2 bit per channel use, even though the set of optimal input distributions for the derived outer bound could not be determined. Toward understanding the Gaussian ICOR, an achievability strategy is evaluated in which the input alphabets at the nonoblivious transmitter are a mixture of discrete and Gaussian random variables, where the cardinality of the discrete part is appropriately chosen as a function of the channel parameters. Surprisingly, as the oblivious receiver intuitively should not be able to jointly decode the intended and interfering messages (whose codebook is unavailable), it is shown that with this choice of input, the capacity region of the symmetric Gaussian ICOR is to within 1/2 log (12πe) ≈ 3.34 bits (per channel use per user) of an outer bound for the classical Gaussian IC with full codebook knowledge at both receivers.
Trellis Coded Block Codes and Applications
"... Abstract—This paper presents a Trellis Coded Modulation (TCM) scheme that is built from Linear Block Codes (LBC). These codes are referred to as Trellis Coded Block Codes (TCBC), and unlike conventional TCM, can be used for both discrete as well as continuous channels. This has been made possible by ..."
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Abstract—This paper presents a Trellis Coded Modulation (TCM) scheme that is built from Linear Block Codes (LBC). These codes are referred to as Trellis Coded Block Codes (TCBC), and unlike conventional TCM, can be used for both discrete as well as continuous channels. This has been made possible by utilizing a new algebraic structure discovered by the authors. This structure allows one to partition any linear block code into subcodes with a constant distance between the code words. As in the conventional TCM scheme, the proposed codeset partitioning is used to increase the minimum distance between code words. Another feature of TCBC is that implementations with and without bandwidth expansion are possible. Simulation results are provided to demonstrate the coding gain obtainable in binary symmetric channel (BSC) and additive white Gaussian noise (AWGN) channel. I.
SIGNAL CONSTELLATIONS FOR MULTILEVEL CODED MODULATION WITH SPARSE GRAPH CODES
"... A method to combine errorcorrection coding and spectral efficient modulation for transmission over channels with Gaussian noise is presented. The method of modulation leads to a signal constellation in which the constellation symbols have a nonuniform distribution. This gives a socalled shape gain ..."
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A method to combine errorcorrection coding and spectral efficient modulation for transmission over channels with Gaussian noise is presented. The method of modulation leads to a signal constellation in which the constellation symbols have a nonuniform distribution. This gives a socalled shape gain which can be as high as πe 6 (1.5 dB). A sparse graph code is constructed which is based on a LDPC code and includes the method of modulation. An efficient decoding algorithm can be derived for this sparse graph code. Simulation results show that the performance of the code is quite good compared to other coded modulation schemes proposed in literature.
1 A LatticeTheoretic Characterization of Optimal MinimumDistance Linear Precoders
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1On the Twouser Interference Channel with Partial Codebook Knowledge at one Receiver
"... In multiuser information theory it is often assumed that every node in the network possesses all codebooks used in the network. This assumption may be impractical in distributed adhoc, cognitive or heterogeneous networks. This work considers the twouser Interference Channel with one Oblivious Rec ..."
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In multiuser information theory it is often assumed that every node in the network possesses all codebooks used in the network. This assumption may be impractical in distributed adhoc, cognitive or heterogeneous networks. This work considers the twouser Interference Channel with one Oblivious Receiver (ICOR), i.e., one receiver lacks knowledge of the interfering codebook while the other receiver knows both codebooks. The paper asks whether, and if so how much, the channel capacity of the ICOR is reduced compared to that of the classical IC where both receivers know all codebooks. A novel outer bound is derived and shown to be achievable to within a constant gap for the class of injective semideterministic ICORs; the gap is shown to be zero for injective fully deterministic ICORs. An exact capacity result is shown for the general memoryless ICOR when the nonoblivious receiver experiences very strong interference. For the linear deterministic ICOR that models the Gaussian noise channel at high SNR, non i.i.d. Bernoulli(1/2) input bits are shown to achieve points not achievable by i.i.d. Bernoulli(1/2) input bits used in the same achievability same. For the realvalued Gaussian ICOR the gap is shown to be at most 1/2 bit per channel use, even though the set of optimal input distributions for the derived outer bound could not be determined. Towards understanding the Gaussian ICOR, an achievability strategy is evaluated in which the input alphabets at the nonoblivious transmitter are a mixture of discrete and Gaussian random variables, where the cardinality of the discrete part is appropriately chosen as a function of the channel parameters. Surprisingly, as the oblivious receiver