摘要 :
In this paper, we discuss a potential multiple access and modulation scheme based on polarized states (PS) of electromagnetic (EM) waves for line-of-sight (LOS) communications. The proposed scheme is theoretic different from the e...
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In this paper, we discuss a potential multiple access and modulation scheme based on polarized states (PS) of electromagnetic (EM) waves for line-of-sight (LOS) communications. The proposed scheme is theoretic different from the existing polar modulation for EDGE and WCDMA systems. We propose the detailed bit representation (modulation) and multiple access scheme using PS. Because of the inflexibility of polarization information in the time and frequency domains, as well as independence of frequency and space, the polarization information can be used independently for wireless communications, i.e., another independent resource domain that can be utilized. Due to the independence between the PS and the specific features of signals (such as waveform, bandwidth and data rate), the discussed polarization division multiple access (PDMA) and polarization modulation (PM) are expected to improve the spectrum utilization effectively. It is proved that the polarization filtering technique can be adopted in the PDMA-PM wireless communications to separate the multiuser signals and demodulate the bit information representing by PS for desired user. Some theoretical analysis is done to demonstrate the feasibility of the proposed scheme, and the simulation results are made to evaluate the performance of the suggested system.
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Future mobile radio systems must fulfill challenging requirements. Some requirements are met by single-carrier-based multiple access (MA) schemes such as CDMA and others by multi-carrier-based MA schemes like OFDMA. MA schemes int...
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Future mobile radio systems must fulfill challenging requirements. Some requirements are met by single-carrier-based multiple access (MA) schemes such as CDMA and others by multi-carrier-based MA schemes like OFDMA. MA schemes integrating the characteristics of both are receiving more and more attention. In this article, candidate MA schemes based on the idea of integration are summarized and classified using a new framework. Moreover, interleaved frequency division multiple access (IFDMA) is shown to be a scheme that combines the advantages of both CDMA and OFDMA and is a promising candidate MA scheme, especially for non-adaptive transmission in the uplink of future mobile radio systems.
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Third generation mobile radio systems will employ TD-CDMA in their TDD mode. In a TD-CDMA mobile radio System, joint-detection is equivalent to solving a least Squares problem with a system matrix that exhibits some Form of block-...
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Third generation mobile radio systems will employ TD-CDMA in their TDD mode. In a TD-CDMA mobile radio System, joint-detection is equivalent to solving a least Squares problem with a system matrix that exhibits some Form of block-Toeplitz structure. This structure can be Successfully exploited by using variations of the Schur Algorithm for computing the QR decomposition of this System matrix.
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In this paper, we describe a formulation of the minimum mean square error (MMSE) joint transmitter-receiver design problem for block-based multiple access communication over intersymbol interference (ISI) channels. Since the direc...
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In this paper, we describe a formulation of the minimum mean square error (MMSE) joint transmitter-receiver design problem for block-based multiple access communication over intersymbol interference (ISI) channels. Since the direct formulation of this problem turns out to be nonconvex, we develop various alternative convex formulations using techniques of linear matrix inequalities (LMIs) and second-order cone programming (SOCP). In particular, we show that the optimal MMSE transceiver design problem can be reformulated as a semidefinite program (SDP), which can be solved using highly efficient interior point methods. When the channel matrices are diagonal (as in cyclic prefixed multicarrier systems), we show that the optimal MMSE transceivers can be obtained by subcarrier allocation and optimal power loading to each subcarrier for all the users. Moreover, the optimal subcarrier allocation and power-loading can be computed fairly simply (in polynomial time) by the relative ratios of the magnitudes of the subchannel gains corresponding to all subcarriers. We also prove that any two users can share no more than one subcarrier in the optimal MMSE transceivers. By exploiting this property, we design an efficient strongly polynomial time algorithm for the determination of optimal powerloading and subcarrier allocation in the two-user case.
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摘要 :
We present an experiment demonstrating the spectralpolarization
coding optical code-division multiple-access system introduced
with a nonideal state of polarization (SOP) matching conditions.
In the proposed system, the encoding a...
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We present an experiment demonstrating the spectralpolarization
coding optical code-division multiple-access system introduced
with a nonideal state of polarization (SOP) matching conditions.
In the proposed system, the encoding and double balanced-detection
processes are implemented using a polarization-diversity scheme. Because
of the quasiorthogonality of Hadamard codes combining with array
waveguide grating routers and a polarization beam splitter, the proposed
codec pair can encode-decode multiple code words of Hadamard code
while retaining the ability for multiple-access interference cancellation.
The experimental results demonstrate that when the system is maintained
with an orthogonal SOP for each user, an effective reduction in
the phase-induced intensity noise is obtained. The analytical SNR values
are found to overstate the experimental results by around 2 dB when the
received effective power is large. This is mainly limited by insertion losses
of components and a nonflattened optical light source. Furthermore, the
matching conditions can be improved by decreasing nonideal influences.
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摘要 :
We present an experiment demonstrating the spectral-polarization coding optical code-division multiple-access system introduced with a nonideal state of polarization (SOP) matching conditions. In the proposed system, the encoding ...
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We present an experiment demonstrating the spectral-polarization coding optical code-division multiple-access system introduced with a nonideal state of polarization (SOP) matching conditions. In the proposed system, the encoding and double balanced-detection processes are implemented using a polarization-diversity scheme. Because of the quasiorthogonality of Hadamard codes combining with array waveguide grating routers and a polarization beam splitter, the proposed codec pair can encode-decode multiple code words of Hadamard code while retaining the ability for multiple-access interference cancellation. The experimental results demonstrate that when the system is maintained with an orthogonal SOP for each user, an effective reduction in the phase-induced intensity noise is obtained. The analytical SNR values are found to overstate the experimental results by around 2 dB when the received effective power is large. This is mainly limited by insertion losses of components and a nonflattened optical light source. Furthermore, the matching conditions can be improved by decreasing nonideal influences.
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Receivers currently employ single- or dual-polarized antennas, which measure one or two components of the received electromagnetic (EM) signal. In rich scattering environments, however, it may be possible to improve performance by...
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Receivers currently employ single- or dual-polarized antennas, which measure one or two components of the received electromagnetic (EM) signal. In rich scattering environments, however, it may be possible to improve performance by using "vector antennas" as they can detect up to six independent components of the EM field. In this paper, theoretical and simulation results are obtained. We consider the design and analysis of vector-antenna receiver for code division multiple access (CDMA) signals. We consider a closed loop power control (CLPC) for a beamformer-Rake receiver for wireless CDMA multiuser system. We will investigate the performance enhancements in Bit Error Rate (BER) using various vector antennas that can respond to two polarization components combined in a frequency selective multipath fading channel.
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This contribution proposes a novel time-domain synchronous frequency division multiple access (TDS-FDMA) scheme to support multi-user uplink application. A unified frame structure for both single-carrier and multi-carrier transmis...
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This contribution proposes a novel time-domain synchronous frequency division multiple access (TDS-FDMA) scheme to support multi-user uplink application. A unified frame structure for both single-carrier and multi-carrier transmissions and the corresponding low-complexity receiver design are derived. Compared with standard cyclic prefix based orthogonal frequency division multiple access systems, the proposed TDS-FDMA scheme improves the spectral efficiency by about 5% to 10% as well as imposes a similarly low computational complexity, while obtaining a slightly better bit error rate performance over Rayleigh fading channels.
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As the ink is drying on 5G New Radio standards, the industry is now setting its sight on specifying the transport network layer to support 5G deployments. Among the contending technologies, passive optical networks (PONs) stand ou...
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As the ink is drying on 5G New Radio standards, the industry is now setting its sight on specifying the transport network layer to support 5G deployments. Among the contending technologies, passive optical networks (PONs) stand out as an attractive choice because of the point-to-multipoint topology for efficient use of fiber resources and the wide deployments around the world. In this paper, we review key 5G wireless transport standards, discuss optical access technologies and standards development activities, and finally, highlight several state-of-the-art PON technologies.
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Multi-carrier technologies in general, and OFDM and MC-CDMA in particular, are quickly becoming an integral part of the wireless landscape. In this first of a two-part survey, the authors present the innovative transmit/receive mu...
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Multi-carrier technologies in general, and OFDM and MC-CDMA in particular, are quickly becoming an integral part of the wireless landscape. In this first of a two-part survey, the authors present the innovative transmit/receive multi-carrier implementation of TDMA and DS-CDMA systems. Specifically, at the transmit side, the pulse shape (in TDMA) and the chip shape (in DS-CDMA) corresponds to a linear combining of in-phase harmonics (called a CI signal). At the receiver side, traditional time-domain processing (equalization in TDMA and RAKE reception in DS-CDMA) is replaced by innovative frequency based processing. Here, receivers decompose pulse (or chip) shapes into carrier subcomponents and recombine these in a manner achieving both high frequency diversity gain and low MAI. The resulting system outperforms traditional TDMA and DS-CDMA systems by 10-14 dB at typical BERs, and, by application of pseudo-orthogonal pulse shapes (chip shapes), is able to double system throughput while maintaining performance gains of up to 8 dB.
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