1,414,081 research outputs found
GTD-based transceivers for decision feedback and bit loading
We consider new optimization problems for transceivers with DFE receivers and linear precoders, which also use bit loading at the transmitter. First, we consider the MIMO QoS (quality of service) problem, which is to minimize the total transmitted power when the bit rate and probability of error of each data stream are specified. The developments of this paper are based on the generalized triangular decomposition (GTD) recently introduced by Jiang, Li, and Hager. It is shown that under some multiplicative majorization conditions there exists a custom GTD-based transceiver which achieves the minimal power. The problem of maximizing the bit rate subject to the total power constraint and given error probability is also considered in this paper. It is shown that the GTD-based systems also give the optimal solutions to the bit rate maximization problem
Improved algorithm for computing separating linear forms for bivariate systems
We address the problem of computing a linear separating form of a system of
two bivariate polynomials with integer coefficients, that is a linear
combination of the variables that takes different values when evaluated at the
distinct solutions of the system. The computation of such linear forms is at
the core of most algorithms that solve algebraic systems by computing rational
parameterizations of the solutions and this is the bottleneck of these
algorithms in terms of worst-case bit complexity. We present for this problem a
new algorithm of worst-case bit complexity \sOB(d^7+d^6\tau) where and
denote respectively the maximum degree and bitsize of the input (and
where \sO refers to the complexity where polylogarithmic factors are omitted
and refers to the bit complexity). This algorithm simplifies and
decreases by a factor the worst-case bit complexity presented for this
problem by Bouzidi et al. \cite{bouzidiJSC2014a}. This algorithm also yields,
for this problem, a probabilistic Las-Vegas algorithm of expected bit
complexity \sOB(d^5+d^4\tau).Comment: ISSAC - 39th International Symposium on Symbolic and Algebraic
Computation (2014
Secret Key Generation from Correlated Sources and Secure Link
In this paper, we study the problem of secret key generation from both
correlated sources and a secure channel. We obtain the optimal secret key rate
in this problem and show that the optimal scheme is to conduct secret key
generation and key distribution jointly, where every bit in the secret channel
will yield more than one bit of secret key rate. This joint scheme is better
than the separation-based scheme, where the secure channel is used for key
distribution, and as a result, every bit in the secure channel can only provide
one bit of secret key rate.Comment: 5 pages, 1 figur
Joint optimization of transceivers with decision feedback and bit loading
The transceiver optimization problem for MIMO
channels has been considered in the past with linear receivers as
well as with decision feedback (DFE) receivers. Joint optimization
of bit allocation, precoder, and equalizer has in the past been
considered only for the linear transceiver (transceiver with linear
precoder and linear equalizer). It has also been observed that
the use of DFE even without bit allocation in general results in
better performance that linear transceivers with bit allocation.
This paper provides a general study of this for transceivers
with the zero-forcing constraint. It is formally shown that when
the bit allocation, precoder, and equalizer are jointly optimized,
linear transceivers and transceivers with DFE have identical
performance in the sense that transmitted power is identical
for a given bit rate and error probability. The developments of
this paper are based on the generalized triangular decomposition
(GTD) recently introduced by Jiang, Li, and Hager. It will be
shown that a broad class of GTD-based systems solve the optimal
DFE problem with bit allocation. The special case of a linear
transceiver with optimum bit allocation will emerge as one of
the many solutions
Tight Bounds on the Synthesis of 3-bit Reversible Circuits: NFT Library
The reversible circuit synthesis problem can be reduced to permutation group.
This allows Schreier-Sims Algorithm for the strong generating set-finding
problem to be used to find tight bounds on the synthesis of 3-bit reversible
circuits using the NFT library. The tight bounds include the maximum and
minimum length of 3-bit reversible circuits, the maximum and minimum cost of
3-bit reversible circuits. The analysis shows better results than that found in
the literature for the lower bound of the cost. The analysis also shows that
there are 1960 universal reversible sub-libraries from the main NFT library.Comment: 18 pages. arXiv admin note: text overlap with arXiv:1101.438
Coding gain in paraunitary analysis/synthesis systems
A formal proof that bit allocation results hold for the entire class of paraunitary subband coders is presented. The problem of finding an optimal paraunitary subband coder, so as to maximize the coding gain of the system, is discussed. The bit allocation problem is analyzed for the case of the paraunitary tree-structured filter banks, such as those used for generating orthonormal wavelets. The even more general case of nonuniform filter banks is also considered. In all cases it is shown that under optimal bit allocation, the variances of the errors introduced by each of the quantizers have to be equal. Expressions for coding gains for these systems are derived
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