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MIMO Architecture for Coherent Optical Wireless Communication: System Design and Performance

JOURNAL OF OPTICAL COMMUNICATIONS AND NETWORKING 2013年第5期5卷 411-420页

作者： Niu, Mingbo Cheng, Julian Holzman, Jonathan F. Univ British Columbia Sch Engn Kelowna BC V1V 1V7 Canada

A coherent multiple-input multiple-output architecture is proposed for optical wireless communications (OWCs) to mitigate atmospheric turbulence effects. Transmitter optical signals operate at distinct carrier frequencies to allow the received optical signals to be separately processed. The accumulated phase noise in each transmission branch can then be independently and electrically compensated. Based on the proposed architecture, several diversity combining techniques are used at the receiver end for system performance evaluation. Three different turbulence models are considered in this paper for different scintillation level ranges, including gamma-gamma turbulence, K-distributed turbulence, and negative exponential turbulence. Closed-form error rate expressions are derived using a series expansion approach. The diversity order in the gamma-gamma turbulence channel is found to depend only on the smaller channel parameter, while the K-distributed and negative exponential turbulence channels are found to have the same diversity order. The presented numerical results demonstrate substantial system performance improvement over single-link coherent OWC.

关键词： multiple-input multiple-output Optical wireless communication Turbulence channels Wavelength diversity

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Integer-Forcing Linear Receiver Design with Slowest Descent Method

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2013年第6期12卷 2788-2796页

作者： Wei, Lili Chen, Wen Shanghai Jiao Tong Univ Dept Elect Engn Shanghai 200240 Peoples R China

Compute-and-forward (CPF) strategy is one category of network coding in which a relay will compute and forward a linear combination of source messages according to the observed channel coefficients, based on the algebraic structure of lattice codes. Recently, based on the idea of CPF, integer forcing (IF) linear receiver architecture for MIMO system has been proposed to recover different integer combinations of lattice codewords for further original message detection. In this paper, we consider the problem of IF linear receiver design with respect to the channel conditions. Instead of exhaustive search, we present practical and efficient suboptimal algorithms to design the IF coefficient matrix with full rank such that the total achievable rate is maximized, based on the slowest descent method. Numerical results demonstrate the effectiveness of our proposed algorithms.

关键词： multiple-input multiple-output linear receiver lattice codes compute-and-forward MMSE

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Mutual information assessment of LOS MIMO systems with reconfigurable antenna arrays

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The Journal of China Universities of Posts and Telecommunications 2013年第5期20卷 51-56,70页

作者： GAO Jun-jun ZHANG Jian-hua TAO Xiao-feng Science and Technology on Information Systems Engineering Laboratory Wireless Technology Innovation Institute Beijing University of Posts and Telecommunications Key Laboratory of Universal Wireless Communication Ministry of Education Beijing University of Posts and Telecommunications

In presence of line-of-sight （LOS） propagation, multiple-input multiple-output （MIMO） systems can achieve maximum capacity over the whole signal-to-noise ratio （SNR） region by deploying reconfigurable antenna arrays. In this paper, the moment generating function （MGF） formulas of the mutual information （MI） is obtained for LOS MIMO systems with reconfigurable arrays. Then the exact expression of the mean MI is derived in an easily evaluated form. The results show an excellent match between the theoretical curves and the Monte-Carlo simulations.

关键词： multiple-input multiple-output line-of-sight mutual information reconfigurable antenna array Wishart

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A Low Complexity Heterodyne Multiband MIMO Receiver with Baseband Automatic Gain Control

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IEICE TRANSACTIONS ON COMMUNICATIONS 2013年第12期E96B卷 3124-3134页

作者： Ohta, Tomoya Denno, Satoshi Morikura, Masahiro Kyoto Univ Grad Sch Informat Kyoto 6068501 Japan Okayama Univ Grad Sch Nat Sci & Technol Okayama 7008530 Japan

This paper proposes a novel heterodyne multiband multiple-input multiple-output (MIMO) receiver with baseband automatic gain control (AGC) for cognitive radios. The proposed receiver uses heterodyne reception implemented with a wide-passband band-pass filter in the radio frequency (RF) stage to be able to receive signals in arbitrary frequency bands. Even when an RF Hilbert transformer is utilized in the receiver, image-band interference occurs due to the imperfection of the Hilbert transformer. In the receiver, analog baseband AGC is introduced to prevent the baseband signals exceeding the voltage reference of analog-to-digital converters (ADCs). This paper proposes a novel technique to estimate the imperfection of the Hilbert transformer in the heterodyne multiband MIMO receiver with baseband AGC. The proposed technique estimates not only the imperfection of the Hilbert transformer but also the AGC gain ratio, and analog devices imperfection in the feedback loop, which enables to offset the imperfection of the Hilbert transformer. The performance of the proposed receiver is verified by using computer simulations. As a result, the required resolution of the ADC is 9 bits in the proposed receiver. Moreover, the proposed receiver has less computational complexity than that with the baseband interference cancellation unless a frequency band is changed every 9 packets or less.

关键词： cognitive radio heterodyne multiband receiver baseband automatic gain control multiple-input multiple-output analog devices imperfection in a feedback loop

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Early Eviction Technique for Low-Complexity Soft-output MIMO Symbol Detection Based on Dijkstra's Algorithm

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES 2013年第11期E96A卷 2302-2305页

作者： Kim, Tae-Hwan Korea Aerosp Univ Sch Elect Telecommun & Comp Engn Goyang Si 412791 Gyungui Do South Korea

This letter presents a technique to reduce the complexity of the soft-output multiple-input multiple-output symbol detection based on Dijkstra's algorithm. By observing that the greedy behavior of Dijkstra's algorithm can entail unnecessary tree-visits for the symbol detection, this letter proposes a technique to evict non-promising candidates early from the search space. The early eviction technique utilizes layer information to determine if a candidate is promising, which is simple but effective. When the SNR is 30 dB for 6 x 6 64-QAM systems, the average number of tree-visits in the proposed method is reduced by 72.1% in comparison to that in the conventional Dijkstra's algorithm-based symbol detection without the early eviction.

关键词： multiple-input multiple-output soft output sphere decoding maximum-likelihood detection tree search

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Robust precoder-decoder design for physical layer network coding-based MIMO two-way relaying system

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EURASIP JOURNAL ON WIRELESS COMMUNICATIONS AND NETWORKING 2013年第1期2013卷 1-16页

作者： Jayasinghe, Laddu Keeth Saliya Rajatheva, Nandana Latva-Aho, Matti Univ Oulu CWC Dept Commun Engn FIN-90570 Oulu Finland

In this paper, we investigate a robust joint precoder-decoder design scheme for a multiple-input multiple-output physical layer network coding (PNC)-based two-way relay system. An orthogonal training sequence is used to estimate the channels. The estimate is imperfect, and a robust design is proposed to find precoders at the source nodes and decoder at the relay node to facilitate PNC operations during multiple-access stage. Both channel estimation error and antenna correlations are used to formulate the optimization problem to minimize the weighted mean square error (WMSE) under a total power constraint. The problem becomes non-convex, and we propose an algorithm to solve it optimally. During the broadcast stage, an algorithm is proposed to find a precoder at the relay node and decoders at source nodes. The system performance is evaluated with estimation error and antenna correlation parameters. The effect of weighting parameters, relay location, and number of antennas at nodes are also considered in the numerical analysis. Numerical results confirm that our joint precoder-decoder algorithms provide the optimal solution to the minimization of WMSE with the total available power.

关键词： Bit error rate Imperfect channel state information Mean square error multiple-input multiple-output Non-convex optimization Physical layer network coding

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Achievable Spatial Throughput in Multi-Antenna Cognitive Underlay Networks with Multi-Hop Relaying

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2013年第8期31卷 1543-1558页

作者： Zaidi, Syed Ali Raza Ghogho, Mounir McLernon, Des C. Swami, Ananthram Univ Leeds Sch Elect & Elect Engn Leeds W Yorkshire England Int Univ Rabat Rabat Morocco US Army Res Lab Adelphi MD USA

In this article, we quantify the achievable spatial throughput of a multi-antenna Poisson cognitive radio network (CRN) collocated with a Poisson multi-antenna primary network. CR users employ Slotted-ALOHA medium access control. The success probability (SP) of a primary link is quantified in the presence of the secondary and primary interferers. It is demonstrated that two fold gains are experienced by employing multiple antennas at primary, i.e., (i) the fixed high desired SP threshold is met;(ii) CRs can also be accommodated without QoS deterioration. Further in this paper, the maximum permissible medium access probability (MAP) for CRN is derived from the link SP and primary users QoS constraint. The impact of the number of antennas and modulation employed at the primary on the permissible MAP of the CRN is also explored. Assuming that CR users employ multi-hop communication, QoS aware relaying with a radian sector forwarding area is studied. The average forward progress (AFP) and isolation probability for a CR user with QoS based connectivity is characterized under the permissible MAP. The spatial throughput for the CRN is quantified by the analysis of the AFP and the permissible MAP. It is shown that there exists an optimal MAP which maximizes the spatial throughput of the CRN. This optimal MAP is coupled with the permissible MAP, density of users, number of antennas and modulation schemes employed in both primary and secondary networks. Lastly, a few important design questions are investigated for multi-hop MIMO underlay CRNs.

关键词： Cognitive radio Poisson point process stochastic geometry multiple-input multiple-output ad-hoc underlay isolation

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Interference alignment for MIMO cognitive networks: a complex FDPM-based subspace tracking approach

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INTERNATIONAL JOURNAL OF EMBEDDED SYSTEMS 2013年第3期5卷 166-174页

作者： Zhu, Bin Ge, Jianhua Li, Jing Shi, Xiaoye Huang, Yunxia Xidian Univ State Key Lab Integrated Serv Networks 2 South Taibai Rd Xian 710071 Shaanxi Peoples R China

Interference alignment (IA) for multiple-input multiple-output (MIMO) cognitive networks is considered by modelling the unlicensed secondary transmitter-receiver pairs which coexist with the licensed multi-antenna primary user as a K-user MIMO interference channel. Starting from investigating the constraint conditions of IA scheme in MIMO cognitive networks, a practical IA algorithm is developed by using a subspace tracking approach based on the complex fast data projection method (FDPM). In the proposed algorithm, first, each secondary transmitter aligns its transmitted signal into the null space of the channel matrix from itself to the primary user without causing any interference to the primary user. Then secondary transmitters and receivers, requiring no channel knowledge of secondary networks, alternately design the precoding and postprocessing matrices through a training period which exploits the complex FDPM-based minor subspace tracking, thus eliminating interference among secondary users. Moreover, the case where secondary transmitters have partial knowledge of channels from themselves to the primary user is also discussed. Simulation results reveal that the proposed algorithm can achieve a high sum rate performance while requiring low computational complexity.

关键词： interference alignment IA subspace tracking fast data projection method FDPM multiple-input multiple-output MIMO cognitive networks sum rate

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Decorrelation MIMO Receiver for Block Fading Channels

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IEEE COMMUNICATIONS LETTERS 2013年第11期17卷 2112-2115页

作者： Mao, Xuehong Chen, Rong-Rong She, Huajun Farhang-Boroujeny, Behrouz Univ Utah ECE Salt Lake City UT USA

In this paper, we propose a novel decorrelation receiver for multiple-input multiple-output (MIMO) block fading channels. The proposed design breaks the correlation between soft-decision-directed channel estimation (SCE) and data detection, and thus improves the performance of existing receivers that do not take such correlation into account. Computer simulations confirm that the decorrelation receiver yields excellent performance when applied to the Markov Chain Monte Carlo (MCMC) MIMO detector and the soft minimum mean-square-error (MMSE) MIMO detector.

关键词： Channel estimation iterative detection Markov chain Monte Carlo multiple-input multiple-output

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A reconfigurable antenna using varactor diode for LTE MIMO applications

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MICROWAVE AND OPTICAL TECHNOLOGY LETTERS 2013年第5期55卷 1141-1145页

作者： Yoon, Cheol Hwang, Sun-Gook Lee, Gi-Chan Kim, Woo-Su Lee, Hwa-Choon Park, Hyo-Dal Inha Univ Dept Elect Engn Inchon 402751 South Korea KEIT Seoul 135080 South Korea Chodang Univ Dept Informat & Commun Engn Muan Gun 534800 Cheon Nam South Korea

In this article, a mobile embedded antenna having tunable capacitance is proposed and the validity of the proposed solution was proved through design, fabrication, and *** antenna can be applied to long-term evolution (LTE) as well as DCS/PCS/WCDMA bands being currently used. Antennas for the 4G mobile service are required to expand its bandwidth so that it includes both LTE band and other service bands. However, it is hard to obtain low-band characteristic due to the limited space for antenna in terminals. The proposed antenna consists of two planar inverted F antennas that are orthogonally arranged. Two radiators should be designed to have equal or enhanced isolation (S21) of lower than 15 dB. To meet this requirement, a varactor diode SMV2109 (skyworks corp.) was used to make the operation frequency of low-band tunable. With the optimized parameters, the antenna was fabricated and measured and the results have been compared with the simulated result. The antenna satisfied with operation frequency and performance for both low-band and high-band, and measured performance of the antenna fabricated with optimized parameters is compared and analyzed with the simulation results. (c) 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:11411145, 2013;View this article online at ***. DOI 10.1002/mop.27479

关键词： reconfigurable antenna varactor diode long-term evolution multiple-input multiple-output

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