8,861 research outputs found
Transceiver Optimization for Two-Hop AF MIMO Relay Systems With DFE Receiver and Direct Link
In this paper, we consider precoding and receiving matrices optimization for a two-hop amplify-and-forward (AF) multiple-input multiple-output (MIMO) relay system with a decision feedback equalizer (DFE) at the destination node in the presence of the direct source-destination link. By adopting the minimum mean-squared error (MMSE) criterion, we develop two new transceiver design algorithms for such a system. The first one employs an iterative procedure to design the source, relay, feed-forward, and feedback matrices. The second algorithm is a non-iterative suboptimal approach which decomposes the optimization problem into two tractable subproblems and obtains the source and relay precoding matrices by solving the two subproblems sequentially. Simulation results validate the better MSE and bit-error-rate (BER) performance of the proposed algorithms and show that the non-iterative suboptimal method has a negligible performance loss when the ratio of the source node transmission power to the relay node transmission power is small. In addition, the computational complexity analysis suggests that the second algorithm and one iteration of the first algorithm have the same order of complexity. As the first algorithm typically converges within a few iterations, both proposed algorithms exhibit a low complexity order
The linear complexity of whiteman's generalized cyclotomic sequences of period p {m+1}q n+1
In this paper, we mainly get three results. First, let p, q be distinct primes with \gcd ((p-1)p,(q-1)q)=\gcd (p-1,q-1)=e ; we give a method to compute the linear complexity of Whiteman's generalized cyclotomic sequences of period p^{m+1}q n+1. Second, if e=4, we compute the exact linear complexity of Whiteman's generalized cyclotomic sequences. Third, if p \equiv q \equiv 5∼({\rm mod}∼8), \gcd (p-1, q-1)=4, and we fix a common primitive root g of both p and q, then 2\in H-{0}=(g), which is a subgroup of the multiplicative group Z-{pq} \ast, if and only if Whiteman's generalized cyclotomic numbers of order 4 depend on the decomposition pq=a^{2}+4b 2 with 4\vert b. © 1963-2012 IEEE.published_or_final_versio
Modelling Time-varying Dark Energy with Constraints from Latest Observations
We introduce a set of two-parameter models for the dark energy equation of
state (EOS) to investigate time-varying dark energy. The models are
classified into two types according to their boundary behaviors at the redshift
and their local extremum properties. A joint analysis based on
four observations (SNe + BAO + CMB + ) is carried out to constrain all the
models. It is shown that all models get almost the same and the cosmological parameters with the
best-fit results , although the constraint results on two
parameters and the allowed regions for the EOS are
sensitive to different models and a given extra model parameter. For three of
Type I models which have similar functional behaviors with the so-called CPL
model, the constrained two parameters and have negative correlation
and are compatible with the ones in CPL model, and the allowed regions of
get a narrow node at . The best-fit results from the most
stringent constraints in Model Ia give which may compare with the best-fit results in the CPL model. For four of
Type II models which have logarithmic function forms and an extremum point, the
allowed regions of are found to be sensitive to different models and a
given extra parameter. It is interesting to obtain two models in which two
parameters and are strongly correlative and appropriately reduced
to one parameter by a linear relation .Comment: 30 pages, 7 figure
Research Program towards Observation of Neutrino-Nucleus Coherent Scattering
The article describes the research program pursued by the TEXONO
Collaboration towards an experiment to observe coherent scattering between
neutrinos and the nucleus at the power reactor. The motivations of studying
this process are surveyed. In particular, a threshold of 100-200 eV has been
achieved with an ultra-low-energy germanium detector prototype. This detection
capability at low energy can also be adapted to conduct searches of Cold Dark
Matter in the low-mass region as well as to enhance the sensitivities in the
study of neutrino magnetic moments.Comment: 5 pages, 8 figures ; Proceedings of TAUP-2005 Workshop, Spain, 2005.
Updated on 2006/9/15 for Proceedings of Neutrino-2006 Conference, Santa Fe,
200
Recent progress on weight distributions of cyclic codes over finite fields
Cyclic codes are an interesting type of linear codes and have wide applications in communication and storage systems due to their efficient encoding and decoding algorithms. In coding theory it is often desirable to know the weight distribution of a cyclic code to estimate the error correcting capability and error probability. In this paper, we present the recent progress on the weight distributions of cyclic codes over finite fields, which had been determined by exponential sums. The cyclic codes with few weights which are very useful are discussed and their existence conditions are listed. Furthermore, we discuss the more general case of constacyclic codes and give some equivalences to characterize their weight distributions
Topological quantum phase transition in an extended Kitaev spin model
We study the quantum phase transition between Abelian and non-Abelian phases
in an extended Kitaev spin model on the honeycomb lattice, where the periodic
boundary condition is applied by placing the lattice on a torus. Our analytical
results show that this spin model exhibits a continuous quantum phase
transition. Also, we reveal the relationship between bipartite entanglement and
the ground-state energy. Our approach directly shows that both the entanglement
and the ground-state energy can be used to characterize the topological quantum
phase transition in the extended Kitaev spin model.Comment: 9 Pages, 4 figure
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