The idea of space-time as a combination of shapeless fundamental elements is proposed.The history of the development of ideas about the discrete space-time structure is analyzed.Quantum space-time is considered as a s...The idea of space-time as a combination of shapeless fundamental elements is proposed.The history of the development of ideas about the discrete space-time structure is analyzed.Quantum space-time is considered as a set of quantum states defined on a set of discretizations with an arbitrary shape of the boundaries of regions.The fundamental element of such space-time is described by the totality of its probabilistic characteristics.We consider a concept in which space-time is the only quantum object,and all material particles and interaction carriers are described as excited states of the fundamental elements of this quantum object.展开更多
The generalized Thirring model with impurity coupling is defined on two-dimensional noncommutativespace-time,a modified propagator and free energy are derived by means of functional integrals method.Moreover,quantum f...The generalized Thirring model with impurity coupling is defined on two-dimensional noncommutativespace-time,a modified propagator and free energy are derived by means of functional integrals method.Moreover,quantum fluctuations and excitation energies are calculated on two-dimensional black hole and soliton background.展开更多
The large scale universe is full of mystery;the dark matter and dark energy amount to respective 23%and 73%of the total energy of the universe,whereas the rest 4%of the total energy is attributed to the normal materia...The large scale universe is full of mystery;the dark matter and dark energy amount to respective 23%and 73%of the total energy of the universe,whereas the rest 4%of the total energy is attributed to the normal material world which can be comprehended by the present science.In the nano-scale quantum world,the EPR(Einstein,Podolsky,and Rosen)paradox and Bells formalism and its experimental tests demonstrated that there is an intrinsic nonlocality present in the quantum world through quantum entanglement which is against the relativity that the information communication between two quanta cannot exceed the speed of light.Even more seriously is the philosophical problem why a deterministic Schrodinger equation describes a particle resulting in a probability interpretation of the particle.In the medium size of the universe,the human brain is mysterious;the human all have consciousness that is the subjective awareness of the inner and outer world which is hard to comprehend in physics;some paranormal phenomena due to the action of the consciousness like finger reading,remote viewing,psychokinesis are even harder to understand.In order to explain these large,medium,and small scale bewildering phenomena in the universe,I proposed two hypotheses in 2014(Lee,2014):(1)The real universe is a complex universe consisting of 8 dimensional(8D)space-time.In addition to our familiar 4D real space-time(Yang),there exists another 4D imaginary space-time(Yin)full of consciousness and information websites which are part of the dark matter.(2)When an object is in a quantum state,the imaginary part of its complex wavefunction(or quantum field)represents the consciousness of the object;the content of the consciousness is determined by the space-time geometry of the real part of the complex wavefunction(quantum mind).This hypothesis provides a scientific basis for pan-psychism that everything has a soul but so long as it enters into the quantum state.展开更多
In this article,we study the DKP equation for the oscillator in a G?del-type space-time background.We derive the final form of this equation in a flat class of G?del-type space-time and solve it analytically,and evalu...In this article,we study the DKP equation for the oscillator in a G?del-type space-time background.We derive the final form of this equation in a flat class of G?del-type space-time and solve it analytically,and evaluate the eigenvalues and corresponding eigenfunctions,in detail.展开更多
We present an alternative sixteen-component hypercomplex scalar-vector values named “space-time sedenions”, generating associative noncommutative space-time Clifford algebra. The generalization of relativistic quant...We present an alternative sixteen-component hypercomplex scalar-vector values named “space-time sedenions”, generating associative noncommutative space-time Clifford algebra. The generalization of relativistic quantum mechanics and field theory equations based on sedenionic wave function and space-time operators is discussed.展开更多
The relativistic quantum motions of the oscillator field(via the Klein–Gordon oscillator equation)under a uniform magnetic field in a topologically non-trivial space-time geometry are analyzed.We solve the Klein–Gor...The relativistic quantum motions of the oscillator field(via the Klein–Gordon oscillator equation)under a uniform magnetic field in a topologically non-trivial space-time geometry are analyzed.We solve the Klein–Gordon oscillator equation using the Nikiforov-Uvarov method and obtain the energy profile and the wave function.We discuss the effects of the non-trivial topology and the magnetic field on the energy eigenvalues.We find that the energy eigenvalues depend on the quantum flux field that shows an analogue of the Aharonov–Bohm effect.Furthermore,we obtain the persistent currents,the magnetization,and the magnetic susceptibility at zero temperature in the quantum system defined in a state and show that these magnetic parameters are modified by various factors.展开更多
Zero-energy state is investigated by taking infinitesimal energy and observing its uncertainty in space-time, adopting quantum mechanics. In this paper, the uncertainty in conventional quantum mechanics is found to be...Zero-energy state is investigated by taking infinitesimal energy and observing its uncertainty in space-time, adopting quantum mechanics. In this paper, the uncertainty in conventional quantum mechanics is found to be interpreted as freedom in space-time, which results in possibility of time travel and space transition of the zero-energy state, which could be information or mind. The wave function of a physical system composed of multiple particles or wave-packets is examined and found that it can be arbitrarily changed by grouping by observers. It leads to an idea that even infinitesimal energy or wave-packets in a heavy physical system may separately exist and it has the infinite freedom of space-time.展开更多
In this paper we consider properties of the four-dimensional space-time manifold M caused by the proposition that, according to the scheme theory, the manifold M is locally isomorphic to the spectrum of the algebra A,...In this paper we consider properties of the four-dimensional space-time manifold M caused by the proposition that, according to the scheme theory, the manifold M is locally isomorphic to the spectrum of the algebra A, M ≅Spec (A), where A is the commutative algebra of distributions of quantum-field densities. Points of the manifold M are defined as maximal ideals of density distributions. In order to determine the algebra A, it is necessary to define multiplication on densities and to eliminate those densities, which cannot be multiplied. This leads to essential restrictions imposed on densities and on space-time properties. It is found that the only possible case, when the commutative algebra A exists, is the case, when the quantum fields are in the space-time manifold M with the structure group SO (3, 1) (Lorentz group). The algebra A consists of distributions of densities with singularities in the closed future light cone subset. On account of the local isomorphism M ≅Spec (A) , the quantum fields exist only in the space-time manifold with the one-dimensional arrow of time. In the fermion sector the restrictions caused by the possibility to define the multiplication on the densities of spinor fields can explain the chirality violation. It is found that for bosons in the Higgs sector the charge conjugation symmetry violation on the densities of states can be observed. This symmetry violation can explain the matter-antimatter imbalance. It is found that in theoretical models with non-abelian gauge fields instanton distributions are impossible and tunneling effects between different topological vacua | n> do not occur. Diagram expansion with respect to the -algebra variables is considered.展开更多
This paper proposes a new step-by-step Chebyshev space-time spectral method to analyze the force vibration of functionally graded material structures.Although traditional space-time spectral methods can reduce the acc...This paper proposes a new step-by-step Chebyshev space-time spectral method to analyze the force vibration of functionally graded material structures.Although traditional space-time spectral methods can reduce the accuracy mismatch between tem-poral low-order finite difference and spatial high-order discre tization,the ir time collocation points must increase dramatically to solve highly oscillatory solutions of structural vibration,which results in a surge in computing time and a decrease in accuracy.To address this problem,we introduced the step-by-step idea in the space-time spectral method.The Chebyshev polynomials and Lagrange's equation were applied to derive discrete spatial goverming equations,and a matrix projection method was used to map the calculation results of prev ious steps as the initial conditions of the subsequent steps.A series of numerical experiments were carried out.The results of the proposed method were compared with those obtained by traditional space-time spectral methods,which showed that higher accuracy could be achieved in a shorter computation time than the latter in highly oscillatory cases.展开更多
Existing orthogonal space-time block coding(OSTBC)schemes for backscatter communication systems cannot achieve a full transmission code rate when the tag is equipped with more than two antennas.In this paper,we propos...Existing orthogonal space-time block coding(OSTBC)schemes for backscatter communication systems cannot achieve a full transmission code rate when the tag is equipped with more than two antennas.In this paper,we propose a quasi-orthogonal spacetime block code(QOSTBC)that can achieve a full transmission code rate for backscatter communication systems with a four-antenna tag and then extend the scheme to support tags with 2i antennas.Specifically,we first present the system model for the backscatter system.Next,we propose the QOSTBC scheme to encode the tag signals.Then,we provide the corresponding maximum likelihood detection algorithms to recover the tag signals.Finally,simulation results are provided to demonstrate that our proposed QOSTBC scheme and the detection algorithm can achieve a better transmission code rate or symbol error rate performance for backscatter communication systems compared with benchmark schemes.展开更多
In this paper,we propose a hybrid decode-and-forward and soft information relaying(HDFSIR)strategy to mitigate error propagation in coded cooperative communications.In the HDFSIR approach,the relay operates in decode-...In this paper,we propose a hybrid decode-and-forward and soft information relaying(HDFSIR)strategy to mitigate error propagation in coded cooperative communications.In the HDFSIR approach,the relay operates in decode-and-forward(DF)mode when it successfully decodes the received message;otherwise,it switches to soft information relaying(SIR)mode.The benefits of the DF and SIR forwarding strategies are combined to achieve better performance than deploying the DF or SIR strategy alone.Closed-form expressions for the outage probability and symbol error rate(SER)are derived for coded cooperative communication with HDFSIR and energy-harvesting relays.Additionally,we introduce a novel normalized log-likelihood-ratio based soft estimation symbol(NL-SES)mapping technique,which enhances soft symbol accuracy for higher-order modulation,and propose a model characterizing the relationship between the estimated complex soft symbol and the actual high-order modulated symbol.Further-more,the hybrid DF-SIR strategy is extended to a distributed Alamouti space-time-coded cooperative network.To evaluate the~performance of the proposed HDFSIR strategy,we implement extensive Monte Carlo simulations under varying channel conditions.Results demonstrate significant improvements with the hybrid technique outperforming individual DF and SIR strategies in both conventional and distributed Alamouti space-time coded cooperative networks.Moreover,at a SER of 10^(-3),the proposed NL-SES mapping demonstrated a 3.5 dB performance gain over the conventional averaging one,highlighting its superior accuracy in estimating soft symbols for quadrature phase-shift keying modulation.展开更多
A quantum gravity version is given to the Brans-Dicke theory.We find that the matter field quantum fluctuation induces the conformal quantum fluctuation of space-time,and that the latter backreacts to the classical sp...A quantum gravity version is given to the Brans-Dicke theory.We find that the matter field quantum fluctuation induces the conformal quantum fluctuation of space-time,and that the latter backreacts to the classical space-time and transforms it from Einstein space-time into the Brans-Dicke one.展开更多
In this work, we make a number of proposals to explain how a world of (4 + 4)-dimensions can be useful for a better understanding of both dark matter and quantum gravity. The key idea is to look for some advantage of ...In this work, we make a number of proposals to explain how a world of (4 + 4)-dimensions can be useful for a better understanding of both dark matter and quantum gravity. The key idea is to look for some advantage of considering self-dual invariants in (4 + 4)-dimensions rather than in a separate context of (1 + 3)-dimensions or (3 + 1)-dimensions. In fact, we show that by considering the duality concept in (4 + 4)-dimensions we may provide an alternative meaning of a framework for loop quantum gravity. Moreover, considering the Dirac equation in (4 + 4)-dimensions for a particle without electric charge and mass, we show that when it is projected into the (1 + 3) and (3 + 1)-worlds may describe a system with electric charge and mass. We also discuss the relation between the three physical scenarios;(4 + 4)-world, black-holes and dark matter.展开更多
One of the main problems of contemporary physics is to find a quantum description of gravity. This present approach attempts to remedy the problem through the quantization of a finite but large flat Minkowski space-ti...One of the main problems of contemporary physics is to find a quantum description of gravity. This present approach attempts to remedy the problem through the quantization of a finite but large flat Minkowski space-time by means of Fourier expansion of the displacement four vector. By applying second quantization techniques, space-time emerges as a superposition of space-time eigen states or lattices of quantized space-time vibrations also known as gravitons. Each lattice element four vector is a graviton and traces out an elementary four volume (lattice cell). The stress-momentum tensor of each graviton defines its curvature and also the curvature of the associated lattice as described by General Relativity. The eigen states of space-time are found to be separated by a quantum of energy equal to the product of the Hubble constant and the Planck constant. The highest energy state is at Planck energies. This paper also shows that gravitons can be absorbed and emitted by the space-time lattice changing the volume of its primitive cells and that particles of observable matter are associated with a graviton whose frequency is equal to the particle’s Compton frequency which the lattice can absorb producing a perturbation in the lattice. The space-time lattice is found to be unstable and decays by radiating low energy gravitons of energy equal to the product of the Hubble constant and the Planck constant. This decay causes the space-time superstructure to expand. The graviton is seen a composite spin 2 particle made from a combination of spin half components of the displacement four vector elements. The spin symmetry of its constituent elements can breakdown to give rise to other vector or scalar bosons. Dark Matter is seen as a consequence of Bose-Einstein statistics of gravitons which results in some regions of the lattice having more energy than others.展开更多
We show that the real existence of quantum-events, resulting from spontaneously broken unitary-evolution by quantum-transactions, can explain the dynamic metric of space-time, governed by Einstein’s equation, if ligh...We show that the real existence of quantum-events, resulting from spontaneously broken unitary-evolution by quantum-transactions, can explain the dynamic metric of space-time, governed by Einstein’s equation, if light-clocks are being used to measure the rhythm of events. In the derivation of Einstein’s equation there naturally arises a term for a cosmological constant <span style="white-space:nowrap;">Λ</span>.展开更多
A new scheme combining a scalable transcoder with space time block codes （STBC） for an orthogonal frequency division multiplexing （OFDM） system is proposed for robust video transmission in dispersive fading channe...A new scheme combining a scalable transcoder with space time block codes （STBC） for an orthogonal frequency division multiplexing （OFDM） system is proposed for robust video transmission in dispersive fading channels. The target application for such a scalable transcoder is to provide successful access to the pre-encoded high quality video MPEG-2 from mobile wireless terminals. In the scalable transcoder, besides outputting the MPEG-4 fine granular scalability （FGS） bitstream, both the size of video frames and the bit rate are reduced. And an array processing algorithm of layer interference suppression is used at the receiver which makes the system structure provide different levels of protection to different layers. Furthermore, by considering the important level of scalable bitstream, the different bitstreams can be given different level protection by the system structure and channel coding. With the proposed system, the concurrent large diversity gain characteristic of STBC and alleviation of the frequency-selective fading effect of OFDM can be achieved. The simulation results show that the proposed schemes integrating scalable transcoding can provide a basic quality of video transmission and outperform the conventional single layer transcoding transmitted under the random and bursty error channel conditions.展开更多
The performance loss of an approximately 3 dB signal-to-noise ratio is always paid with conventional differential detection compared to the related coherent detection. A new detection scheme consisting of two steps is...The performance loss of an approximately 3 dB signal-to-noise ratio is always paid with conventional differential detection compared to the related coherent detection. A new detection scheme consisting of two steps is proposed for the differential unitary space-time modulation （DUSTM） system. In the first step, the data sequence is estimated by conventional unitary space-time demodulation （DUSTD） and differentially encoded again to produce an initial estimate of the transmitted symbol stream. In the second step, the initial estimate of the symbol stream is utilized to initialize an expectation maximization （EM）-based iterative detector. In each iteration, the most recent detected symbol stream is employed to estimate the channel, which is then used to implement coherent sequence detection to refine the symbol stream. Simulation results show that the proposed detection scheme performs much better than the conventional DUSTD after several iterations.展开更多
A design of super-orthogonal space-time trellis codes （SOSTTCs） based on the trace criterion （TC） is proposed for improving the design of SOSTTCs. The shortcomings of the rank and determinant criteria based design...A design of super-orthogonal space-time trellis codes （SOSTTCs） based on the trace criterion （TC） is proposed for improving the design of SOSTTCs. The shortcomings of the rank and determinant criteria based design and the advantages of the TC-based design are analyzed. The optimization principle of four factors is presented, which includes the space-time block coding （STBC） scheme, set partitioning, trellis structure, and the assignment of signal subsets and STBC schemes in the trellis. According to this principle, systematical and handcrafted design steps are given in detail. By constellation expansion, the code performance can be further improved. The code design results are given, and the new codes outperform others in the simulation.展开更多
A method of space-time block coding （STBC） system based on adaptive beamforming of cyclostationarity signal algorithm is proposed.The method uses cyclostationarity of signals to achieve adaptive beamforming,then con...A method of space-time block coding （STBC） system based on adaptive beamforming of cyclostationarity signal algorithm is proposed.The method uses cyclostationarity of signals to achieve adaptive beamforming,then constructs a pair of low correlated transmit beams based on beamform estimation of multiple component signals of uplink.Using these two selected transmit beams,signals encoded by STBC are transmitted to achieve diversity gain and beamforming gain at the same time,and increase the signal to noise ratio （SNR） of downlink.With simple computation and fast convergence performance,the proposed scheme is applicable for time division multiple access （TDMA） wireless communication operated in a complex interference environment.Simulation results show that the proposed scheme has better performance than conventional STBC,and can obtain a gain of about 5 dB when the bit error ratio （BER） is 10-4.展开更多
文摘The idea of space-time as a combination of shapeless fundamental elements is proposed.The history of the development of ideas about the discrete space-time structure is analyzed.Quantum space-time is considered as a set of quantum states defined on a set of discretizations with an arbitrary shape of the boundaries of regions.The fundamental element of such space-time is described by the totality of its probabilistic characteristics.We consider a concept in which space-time is the only quantum object,and all material particles and interaction carriers are described as excited states of the fundamental elements of this quantum object.
基金Supported by the Natural Science Foundation of Sichuan Education Committee under Grant No.08ZA038
文摘The generalized Thirring model with impurity coupling is defined on two-dimensional noncommutativespace-time,a modified propagator and free energy are derived by means of functional integrals method.Moreover,quantum fluctuations and excitation energies are calculated on two-dimensional black hole and soliton background.
文摘The large scale universe is full of mystery;the dark matter and dark energy amount to respective 23%and 73%of the total energy of the universe,whereas the rest 4%of the total energy is attributed to the normal material world which can be comprehended by the present science.In the nano-scale quantum world,the EPR(Einstein,Podolsky,and Rosen)paradox and Bells formalism and its experimental tests demonstrated that there is an intrinsic nonlocality present in the quantum world through quantum entanglement which is against the relativity that the information communication between two quanta cannot exceed the speed of light.Even more seriously is the philosophical problem why a deterministic Schrodinger equation describes a particle resulting in a probability interpretation of the particle.In the medium size of the universe,the human brain is mysterious;the human all have consciousness that is the subjective awareness of the inner and outer world which is hard to comprehend in physics;some paranormal phenomena due to the action of the consciousness like finger reading,remote viewing,psychokinesis are even harder to understand.In order to explain these large,medium,and small scale bewildering phenomena in the universe,I proposed two hypotheses in 2014(Lee,2014):(1)The real universe is a complex universe consisting of 8 dimensional(8D)space-time.In addition to our familiar 4D real space-time(Yang),there exists another 4D imaginary space-time(Yin)full of consciousness and information websites which are part of the dark matter.(2)When an object is in a quantum state,the imaginary part of its complex wavefunction(or quantum field)represents the consciousness of the object;the content of the consciousness is determined by the space-time geometry of the real part of the complex wavefunction(quantum mind).This hypothesis provides a scientific basis for pan-psychism that everything has a soul but so long as it enters into the quantum state.
文摘In this article,we study the DKP equation for the oscillator in a G?del-type space-time background.We derive the final form of this equation in a flat class of G?del-type space-time and solve it analytically,and evaluate the eigenvalues and corresponding eigenfunctions,in detail.
文摘We present an alternative sixteen-component hypercomplex scalar-vector values named “space-time sedenions”, generating associative noncommutative space-time Clifford algebra. The generalization of relativistic quantum mechanics and field theory equations based on sedenionic wave function and space-time operators is discussed.
文摘The relativistic quantum motions of the oscillator field(via the Klein–Gordon oscillator equation)under a uniform magnetic field in a topologically non-trivial space-time geometry are analyzed.We solve the Klein–Gordon oscillator equation using the Nikiforov-Uvarov method and obtain the energy profile and the wave function.We discuss the effects of the non-trivial topology and the magnetic field on the energy eigenvalues.We find that the energy eigenvalues depend on the quantum flux field that shows an analogue of the Aharonov–Bohm effect.Furthermore,we obtain the persistent currents,the magnetization,and the magnetic susceptibility at zero temperature in the quantum system defined in a state and show that these magnetic parameters are modified by various factors.
文摘Zero-energy state is investigated by taking infinitesimal energy and observing its uncertainty in space-time, adopting quantum mechanics. In this paper, the uncertainty in conventional quantum mechanics is found to be interpreted as freedom in space-time, which results in possibility of time travel and space transition of the zero-energy state, which could be information or mind. The wave function of a physical system composed of multiple particles or wave-packets is examined and found that it can be arbitrarily changed by grouping by observers. It leads to an idea that even infinitesimal energy or wave-packets in a heavy physical system may separately exist and it has the infinite freedom of space-time.
文摘In this paper we consider properties of the four-dimensional space-time manifold M caused by the proposition that, according to the scheme theory, the manifold M is locally isomorphic to the spectrum of the algebra A, M ≅Spec (A), where A is the commutative algebra of distributions of quantum-field densities. Points of the manifold M are defined as maximal ideals of density distributions. In order to determine the algebra A, it is necessary to define multiplication on densities and to eliminate those densities, which cannot be multiplied. This leads to essential restrictions imposed on densities and on space-time properties. It is found that the only possible case, when the commutative algebra A exists, is the case, when the quantum fields are in the space-time manifold M with the structure group SO (3, 1) (Lorentz group). The algebra A consists of distributions of densities with singularities in the closed future light cone subset. On account of the local isomorphism M ≅Spec (A) , the quantum fields exist only in the space-time manifold with the one-dimensional arrow of time. In the fermion sector the restrictions caused by the possibility to define the multiplication on the densities of spinor fields can explain the chirality violation. It is found that for bosons in the Higgs sector the charge conjugation symmetry violation on the densities of states can be observed. This symmetry violation can explain the matter-antimatter imbalance. It is found that in theoretical models with non-abelian gauge fields instanton distributions are impossible and tunneling effects between different topological vacua | n> do not occur. Diagram expansion with respect to the -algebra variables is considered.
基金supported by the Advance Research Project of Civil Aerospace Technology(Grant No.D020304)National Nat-ural Science Foundation of China(Grant Nos.52205257 and U22B2083).
文摘This paper proposes a new step-by-step Chebyshev space-time spectral method to analyze the force vibration of functionally graded material structures.Although traditional space-time spectral methods can reduce the accuracy mismatch between tem-poral low-order finite difference and spatial high-order discre tization,the ir time collocation points must increase dramatically to solve highly oscillatory solutions of structural vibration,which results in a surge in computing time and a decrease in accuracy.To address this problem,we introduced the step-by-step idea in the space-time spectral method.The Chebyshev polynomials and Lagrange's equation were applied to derive discrete spatial goverming equations,and a matrix projection method was used to map the calculation results of prev ious steps as the initial conditions of the subsequent steps.A series of numerical experiments were carried out.The results of the proposed method were compared with those obtained by traditional space-time spectral methods,which showed that higher accuracy could be achieved in a shorter computation time than the latter in highly oscillatory cases.
基金supported by Beijing Municipal Natural Science Foundation(L222002)the Natural Science Foundation of China(U22B2004).
文摘Existing orthogonal space-time block coding(OSTBC)schemes for backscatter communication systems cannot achieve a full transmission code rate when the tag is equipped with more than two antennas.In this paper,we propose a quasi-orthogonal spacetime block code(QOSTBC)that can achieve a full transmission code rate for backscatter communication systems with a four-antenna tag and then extend the scheme to support tags with 2i antennas.Specifically,we first present the system model for the backscatter system.Next,we propose the QOSTBC scheme to encode the tag signals.Then,we provide the corresponding maximum likelihood detection algorithms to recover the tag signals.Finally,simulation results are provided to demonstrate that our proposed QOSTBC scheme and the detection algorithm can achieve a better transmission code rate or symbol error rate performance for backscatter communication systems compared with benchmark schemes.
基金funded by the Deanship of Graduate Studies and Scientific Research at Jouf University under grant No.(DGSSR-2024-02-02160).
文摘In this paper,we propose a hybrid decode-and-forward and soft information relaying(HDFSIR)strategy to mitigate error propagation in coded cooperative communications.In the HDFSIR approach,the relay operates in decode-and-forward(DF)mode when it successfully decodes the received message;otherwise,it switches to soft information relaying(SIR)mode.The benefits of the DF and SIR forwarding strategies are combined to achieve better performance than deploying the DF or SIR strategy alone.Closed-form expressions for the outage probability and symbol error rate(SER)are derived for coded cooperative communication with HDFSIR and energy-harvesting relays.Additionally,we introduce a novel normalized log-likelihood-ratio based soft estimation symbol(NL-SES)mapping technique,which enhances soft symbol accuracy for higher-order modulation,and propose a model characterizing the relationship between the estimated complex soft symbol and the actual high-order modulated symbol.Further-more,the hybrid DF-SIR strategy is extended to a distributed Alamouti space-time-coded cooperative network.To evaluate the~performance of the proposed HDFSIR strategy,we implement extensive Monte Carlo simulations under varying channel conditions.Results demonstrate significant improvements with the hybrid technique outperforming individual DF and SIR strategies in both conventional and distributed Alamouti space-time coded cooperative networks.Moreover,at a SER of 10^(-3),the proposed NL-SES mapping demonstrated a 3.5 dB performance gain over the conventional averaging one,highlighting its superior accuracy in estimating soft symbols for quadrature phase-shift keying modulation.
文摘A quantum gravity version is given to the Brans-Dicke theory.We find that the matter field quantum fluctuation induces the conformal quantum fluctuation of space-time,and that the latter backreacts to the classical space-time and transforms it from Einstein space-time into the Brans-Dicke one.
文摘In this work, we make a number of proposals to explain how a world of (4 + 4)-dimensions can be useful for a better understanding of both dark matter and quantum gravity. The key idea is to look for some advantage of considering self-dual invariants in (4 + 4)-dimensions rather than in a separate context of (1 + 3)-dimensions or (3 + 1)-dimensions. In fact, we show that by considering the duality concept in (4 + 4)-dimensions we may provide an alternative meaning of a framework for loop quantum gravity. Moreover, considering the Dirac equation in (4 + 4)-dimensions for a particle without electric charge and mass, we show that when it is projected into the (1 + 3) and (3 + 1)-worlds may describe a system with electric charge and mass. We also discuss the relation between the three physical scenarios;(4 + 4)-world, black-holes and dark matter.
文摘One of the main problems of contemporary physics is to find a quantum description of gravity. This present approach attempts to remedy the problem through the quantization of a finite but large flat Minkowski space-time by means of Fourier expansion of the displacement four vector. By applying second quantization techniques, space-time emerges as a superposition of space-time eigen states or lattices of quantized space-time vibrations also known as gravitons. Each lattice element four vector is a graviton and traces out an elementary four volume (lattice cell). The stress-momentum tensor of each graviton defines its curvature and also the curvature of the associated lattice as described by General Relativity. The eigen states of space-time are found to be separated by a quantum of energy equal to the product of the Hubble constant and the Planck constant. The highest energy state is at Planck energies. This paper also shows that gravitons can be absorbed and emitted by the space-time lattice changing the volume of its primitive cells and that particles of observable matter are associated with a graviton whose frequency is equal to the particle’s Compton frequency which the lattice can absorb producing a perturbation in the lattice. The space-time lattice is found to be unstable and decays by radiating low energy gravitons of energy equal to the product of the Hubble constant and the Planck constant. This decay causes the space-time superstructure to expand. The graviton is seen a composite spin 2 particle made from a combination of spin half components of the displacement four vector elements. The spin symmetry of its constituent elements can breakdown to give rise to other vector or scalar bosons. Dark Matter is seen as a consequence of Bose-Einstein statistics of gravitons which results in some regions of the lattice having more energy than others.
文摘We show that the real existence of quantum-events, resulting from spontaneously broken unitary-evolution by quantum-transactions, can explain the dynamic metric of space-time, governed by Einstein’s equation, if light-clocks are being used to measure the rhythm of events. In the derivation of Einstein’s equation there naturally arises a term for a cosmological constant <span style="white-space:nowrap;">Λ</span>.
文摘A new scheme combining a scalable transcoder with space time block codes （STBC） for an orthogonal frequency division multiplexing （OFDM） system is proposed for robust video transmission in dispersive fading channels. The target application for such a scalable transcoder is to provide successful access to the pre-encoded high quality video MPEG-2 from mobile wireless terminals. In the scalable transcoder, besides outputting the MPEG-4 fine granular scalability （FGS） bitstream, both the size of video frames and the bit rate are reduced. And an array processing algorithm of layer interference suppression is used at the receiver which makes the system structure provide different levels of protection to different layers. Furthermore, by considering the important level of scalable bitstream, the different bitstreams can be given different level protection by the system structure and channel coding. With the proposed system, the concurrent large diversity gain characteristic of STBC and alleviation of the frequency-selective fading effect of OFDM can be achieved. The simulation results show that the proposed schemes integrating scalable transcoding can provide a basic quality of video transmission and outperform the conventional single layer transcoding transmitted under the random and bursty error channel conditions.
基金The National Natural Science Foundation of China(No60572072,60496311)the National High Technology Research and Development Program of China (863Program) (No2006AA01Z264)+1 种基金the National Basic Research Program of China (973Program) (No2007CB310603)the PhD Programs Foundation of Ministry of Educa-tion of China (No20060286016)
文摘The performance loss of an approximately 3 dB signal-to-noise ratio is always paid with conventional differential detection compared to the related coherent detection. A new detection scheme consisting of two steps is proposed for the differential unitary space-time modulation （DUSTM） system. In the first step, the data sequence is estimated by conventional unitary space-time demodulation （DUSTD） and differentially encoded again to produce an initial estimate of the transmitted symbol stream. In the second step, the initial estimate of the symbol stream is utilized to initialize an expectation maximization （EM）-based iterative detector. In each iteration, the most recent detected symbol stream is employed to estimate the channel, which is then used to implement coherent sequence detection to refine the symbol stream. Simulation results show that the proposed detection scheme performs much better than the conventional DUSTD after several iterations.
文摘A design of super-orthogonal space-time trellis codes （SOSTTCs） based on the trace criterion （TC） is proposed for improving the design of SOSTTCs. The shortcomings of the rank and determinant criteria based design and the advantages of the TC-based design are analyzed. The optimization principle of four factors is presented, which includes the space-time block coding （STBC） scheme, set partitioning, trellis structure, and the assignment of signal subsets and STBC schemes in the trellis. According to this principle, systematical and handcrafted design steps are given in detail. By constellation expansion, the code performance can be further improved. The code design results are given, and the new codes outperform others in the simulation.
文摘A method of space-time block coding （STBC） system based on adaptive beamforming of cyclostationarity signal algorithm is proposed.The method uses cyclostationarity of signals to achieve adaptive beamforming,then constructs a pair of low correlated transmit beams based on beamform estimation of multiple component signals of uplink.Using these two selected transmit beams,signals encoded by STBC are transmitted to achieve diversity gain and beamforming gain at the same time,and increase the signal to noise ratio （SNR） of downlink.With simple computation and fast convergence performance,the proposed scheme is applicable for time division multiple access （TDMA） wireless communication operated in a complex interference environment.Simulation results show that the proposed scheme has better performance than conventional STBC,and can obtain a gain of about 5 dB when the bit error ratio （BER） is 10-4.
