In this letter, we consider a multiple-input multiple-output two-way cognitive radio system under a spectrum sharing scenario, where primary and secondary users operate on the same frequency band. The secondary termin...
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In this letter, we consider a multiple-input multiple-output two-way cognitive radio system under a spectrum sharing scenario, where primary and secondary users operate on the same frequency band. The secondary terminals aims to exchange different messages with each other using multiple relays where each relay employs an amplify-and-forward strategy. The main objective of our work is to maximize the secondary sum rate allowed to share the spectrum with the primary users by respecting a primary user tolerated interference threshold. In this context, we derive an analytical expression of the optimal power allocated to each antenna of the terminals. We then discuss the impact of some system parameters on the performance in the numerical result section.
A multiantenna system comprising of an eight-element antenna array in mobile terminal is presented. In this work, two sets of eight-element antenna structures based on capacitive coupling element and inverted-F antenn...
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A multiantenna system comprising of an eight-element antenna array in mobile terminal is presented. In this work, two sets of eight-element antenna structures based on capacitive coupling element and inverted-F antennas operating at 3400-3600 MHz long-term evolution frequency band are designed. The structures are estimated to achieve a good effective diversity gain in both uniform and nonuniform environments. It is also shown that the proposed structures achieve an ergodic multiple-input multiple-output (MIMO) capacity of only 1.2 bit/(s Hz) lower than the capacity achieved by ideal uncorrelated antennas. A prototype is fabricated to validate the simulation results. The result shows that the structure exhibited the highest mutual coupling of -10 dB across the required frequency band. Therefore, the proposed structure is a good candidate for implementing diversity and MIMO in mobile terminals. (c) 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1323-1327, 2014
Wideband loop antennas with distributed elements are proposed for a fourth generation (4G) multiple-input multiple-output (MIMO) mobile terminal. The MIMO antenna system consists of two wideband loop antenna elements ...
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Wideband loop antennas with distributed elements are proposed for a fourth generation (4G) multiple-input multiple-output (MIMO) mobile terminal. The MIMO antenna system consists of two wideband loop antenna elements (Elements #1 and #3), working in the LTE Band 7 (0.88–0.96 GHz), and a printed U-shaped monopole antenna element (Element #2), operating in the WiMAX/WLAN bands (2.0–2.8 GHz). To improve the performances of antenna elements, the distributed elements are employed to reduce the antenna volume, to realize the wideband property, and to modify the input impedance of antenna elements. The arrangement of each antenna element is carefully justified and each element is located at different corners of the ground plane to improve the isolation and envelope correlation coefficient (ECC) characteristics. The MIMO antenna has an ECC lower than 0.1 and isolation higher than 11 dB over the frequency bands of interest. ? 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:577–581, 2014
In this paper, we propose a novel low-complexity detection technique for conventional Spatial Modulation (SM). The proposed scheme is compared to SM with optimal detection (SMOD), SM with signal vector based detection...
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In this paper, we propose a novel low-complexity detection technique for conventional Spatial Modulation (SM). The proposed scheme is compared to SM with optimal detection (SMOD), SM with signal vector based detection (SM-SVD) and another reduced complexity detection technique, presented in the literature. The numerical results show that the proposed scheme can match the error performance of SM-OD very closely, even at low bit-error rate (BER). The computational complexity at the receiver, is shown to be independent of the symbol constellation size, and hence, offers a much lower complexity compared to existing schemes. To further improve the error performance, we then propose two closed-loop transmit antenna selection (TAS) schemes for conventional SM. We assume the receiver has knowledge of the channel and a perfect low-bandwidth feedback path to the transmitter exists. From evaluation of the BER versus normalized signal-to-noise ratio (SNR) and the complexity analysis, the proposed schemes exhibit a significant improvement over SM-OD and other improved SM schemes in terms of error performance and/or complexity.
In this paper, the degrees of freedom (DoF) regions of constant coefficient multiple antenna interference channels are investigated. First, we consider a K-user Gaussian interference channel with M-k antennas at trans...
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In this paper, the degrees of freedom (DoF) regions of constant coefficient multiple antenna interference channels are investigated. First, we consider a K-user Gaussian interference channel with M-k antennas at transmitter k, 1 <= k <= K, and N-j antennas at receiver j, 1 <= j <= K, denoted as a (K, [M-k], [N-j]) channel. Relying on a result of simultaneous Diophantine approximation, a real interference alignment scheme with joint receive antenna processing is developed. The scheme is used to obtain an achievable DoF region. The proposed DoF region includes two previously known results as special cases, namely: 1) the total DoF of (K, [N], [N]) interference channel with K users and N antennas at each node is NK/2 and 2) the total DoF of a (K, [M], [N]) channel is at least KMN/(M + N). We next explore constant-coefficient interference networks with K transmitters and J receivers, all having N antennas. Each transmitter emits an independent message and each receiver requests an arbitrary subset of the messages. Employing the novel joint receive antenna processing, the DoF region for this setup is obtained. We finally consider wireless X networks where each node is allowed to have an arbitrary number of antennas. It is shown that the joint receive antenna processing can be used to establish an achievable DoF region, which is larger than what is possible with antenna splitting. As a special case of the derived achievable DoF region for constant coefficient X network, the total DoF of wireless X networks with the same number of antennas at all nodes and with joint antenna processing is tight while the best inner bound based on antenna splitting cannot meet the outer bound. Finally, we obtain a DoF region outer bound based on the technique of transmitter grouping.
This paper investigates the performance of an overloaded multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system with a repetition code. It has been demonstrated that diversity w...
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ISBN:
(纸本)9781479961207
This paper investigates the performance of an overloaded multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system with a repetition code. It has been demonstrated that diversity with block coding prevents the performance degradation induced by signal multiplexing. However, the computational complexity of a joint decoding scheme increases exponentially with the number of multiplexed signal streams. Thus, this paper proposes the use of a repetition code in the overloaded MIMO-OFDM system. In addition, QR decomposition with M-algorithm (QRM) maximum likelihood decoding (MLD) is applied to the decoding of the repetition code. QRM-MLD significantly reduces the amount of joint decoding complexity. In addition, virtual antennas are employed in order to increase the throughput that is reduced by the repetition code. It is shown that the proposed scheme reduces the complexity by about 1/48 for 6 signal streams with QPSK modulation while the BER degradation is less than 0.1dB at the BER of 10(-3).
Next-generation access networks require simultaneous provision of wired and wireless services and high data rate to meet the huge demands for mobility and multiple services. In this paper, we propose a spectral effici...
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ISBN:
(纸本)9781479948833
Next-generation access networks require simultaneous provision of wired and wireless services and high data rate to meet the huge demands for mobility and multiple services. In this paper, we propose a spectral efficient radio over fiber scheme to simultaneously provide two spatial multiplexed multipleinputmultipleoutput (MIMO) wireless signals with baseband (BB) signal in one wavelength using a centralized light source. The proposed scheme can be applicable in wavelength division multiplexed passive optical network (WDM-PON). The BB signal is modulated at low extinction ratio. Using the same modulated light, the two MIMO signals that have the same career frequency are combined optically using polarization-division-multiplexing (PDM). The BER performance of 10(-9) is achieved for the three signals after transmission of 20 km single mode fiber (SMF).
In this paper, we will analyze the Least Mean Square(LMS) and Recursive Least Square(RLS) algorithms. Then, we apply these two algorithms toa multiple-input multiple-output(MIMO-OFDM) system based on Space-Time Block ...
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ISBN:
(纸本)9781479942152
In this paper, we will analyze the Least Mean Square(LMS) and Recursive Least Square(RLS) algorithms. Then, we apply these two algorithms toa multiple-input multiple-output(MIMO-OFDM) system based on Space-Time Block Coding(STBC), and do some simulations on these two algorithms. From the simulation, it is found that the convergence speed of the RLS algorithm is faster than LMS algorithm, i.e., the performance of RLS is better than LMS algorithm.
In this contribution, we analyze the average symbol error rate (SER) of space-time block coded (STBC) multiple-input multiple-output (MIMO) system over Nakagami-m fading channel with M-PSK constellation in the presenc...
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ISBN:
(纸本)9781479936892
In this contribution, we analyze the average symbol error rate (SER) of space-time block coded (STBC) multiple-input multiple-output (MIMO) system over Nakagami-m fading channel with M-PSK constellation in the presence of multiple keyholes. We derived the expression of channel transmission matrix which was further statistically analyzed to find the probability density function (PDF) of instantaneous signal to noise ratio (SNR) for the channel containing multiple keyholes between it's source and destination end. By performing (p-1)-fold convolution of the individual PDFs of instantaneous SNRs we derived the overall PDF of the multiple keyhole channel, which was used to derive the expression for average SER of the system. Furthermore, we examined the effect of multiple keyholes on the system performance. Result shows that with the increase of number of keyholes, a significant improvement in the system performance takes place. For a given number of keyholes, by increasing the number of receive antennas further improvement in the system performance is observed.
A multiple-input-multiple-output (MIMO) channel manipulation using tunable passive repeater is presented in this paper. The passive repeater has multiple antennas and each of them has a phase-shifter function. The MIM...
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ISBN:
(纸本)9784902339314
A multiple-input-multiple-output (MIMO) channel manipulation using tunable passive repeater is presented in this paper. The passive repeater has multiple antennas and each of them has a phase-shifter function. The MIMO channel capacity is maximized by controlling all elements individually in the passive repeater. The effectiveness of the proposed passive repeater is evaluated numerically and experimentally. From these results, it is found that the MIMO channel capacity can be improved by about 40 % due to the tunability of the passive repeater.
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