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Beam alignment based on antenna array is a promising technique for millimeter wave communication in 5G. In this paper, we investigate the key parameters design under the framework of a two-layer beam alignment which includes wide beam training and narrow beam alignment. Firstly, an equivalent channel model with variant angles is proposed to simplify simulations. Secondly, the period of beam training...
We study the robust security-aware beamforming optimization for cognitive interference channel with confidential messages under the imperfect channel state information (CSI) at each cognitive transmitter. The considered problem is formulated as minimizing the total secondary transmitter power under the subject of the each secondary transmitter constraint while guaranteeing the security communication...
When the size of a target or the rotation angle is large, migration through resolution cell may occur in the bistatic inverse synthetic aperture radar (Bi-ISAR) which will affect the imaging quality. A correction algorithm based on the minimum criterion of image entropy is proposed in this paper. The rotating center is estimated according to this criterion. Then the phase compensation term is constructed...
Millimeter-wave communication is deemed to be one of the promising solutions to meet the growing traffic explosion for the next generation wireless communication system. The compact design of millimeter-wave antenna makes it possible to form large number of narrow beams to cover a certain area. However, the number of beams that can be scheduled simultaneously is not as many as possible due to the...
We present a direct sampling full-band capture receiver for cable and digital TV applications. It consists of a 28nm CMOS ADC-based direct sampling receiver and a 0.18um BiCMOS LNA. It is capable of receiving 158 channels from 48MHz to 1000MHz simultaneously, achieving up to 10Gb/s data throughput, while exceeding DOCSIS requirements. The CMOS receiver occupies 1mm2 area while consuming 300mW. The...
This paper presents a collaborative beamforming design under imperfect channel state information (CSI) assumption for a multiple single-antenna two-way relay network with reciprocal channels. In practical scenario, the channel estimation is always inaccurate at relay nodes. Aiming to tackle the performance degradation caused by the imperfect CSI, we propose a robust beamforming scheme with hypothesis...
This paper proposes an unified distributed spectrum sensing model for analyzing the overlay, underlay and hybrid overlay/underlay paradigms in a distributed cognitive radio network where there are one primary channel and multiple secondary user (SU) pairs, and the co-channel interference is present. At each SU, the energy detection scheme is employed to identify the usage of the primary channel and...
Selective relaying based on instantaneous channel status is usually adopted to improve transmission performance in cooperative communication systems. However, such scheme has an extremely high computational complexity. To reduce the complexity, we propose a selective cooperation scheme to decide whether cooperative transmission should be adopted or not by utilizing statistical channel information...
Event region detection is an important problem in wireless sensor networks. However, a fundamental assumption required for the event-region detection schemes proposed in the literature is that the event-region under detection is quasi-static, i.e., the event-regions do not change during the detection period. This assumption could fail in detecting fast varying events, such as forest fire events and...
Energy detection (ED) is a popular spectrum sensing technique for cognitive radios. The study of ED which takes into account the dynamic of traffic patterns of primary users, in the form of random signal arrival and departure, is of both theoretical and practical importance. Some of the existing works, however, resort to certain approximation techniques to characterize the detection performance. In...
Underwater acoustic channel is always a 2-D dispersive channel. For 2-D least-squares channel estimation, the design of training symbols is an open problem. In this paper, (i) we derive the optimal relation between the dimensions of the training matrix and the ffective memory lengths of the equivalent discrete-time channel model, and (ii) we propose a simple algorithm for searching suitable training...
This paper considers the decode-and-forward (DF) relaying scheme in cooperative communication networks. Specifically, this study considers a cooperative network, in which each relay can obtain perfect channel state information (CSI) from the source to itself, and the destination can acquire perfect CSI from all the relays to itself, but the destination does not need all CSI from the source to all...
We consider a cooperative beamforming system with the amplify-and-forward protocol. To reduce the signaling overhead, each relay quantizes the SNR of the source-to-relay (S-R) link into one bit, which is then transmitted through a binary symmetric channel (BSC) with a known crossover probability to the destination. Given the set of the error-corrupted one-bit messages received at the destination,...
In wireless packet-forwarding networks, selfish nodes always want to maximize their utilities and do not like to help others forward data streams, thus causing severe network performance degradation. To solve the packet-forwarding problem, a novel coalitional game approach based on the selective decode-and-forward (SDF) relaying scheme is proposed. In the game-theoretic analysis, we study the properties...
We study a 2-user 2-hop network with 2 relays in which channel coefficients are independently drawn from continuous distributions and vary over time. For a broad class of channel distributions, we characterize the ergodic sum capacity within a constant number of bits/sec/Hz, independent of signal-to-noise ratio. Specifically, we characterize the ergodic sum capacity within 4 bits/sec/Hz for independent...
The ongoing development of wireless sensor networks (WSNs) demands not only low-power sensors and less system cost but also good performance. Considering this background, investigating a new technology to satisfy both requirements is an important issue for current development of wireless sensor network systems. In this paper, we consider the situation that the sensor nodes in WSNs are deployed in...
Energy consumption is a vital concern when implementing distributed decision fusion in most wireless sensor networks. This paper studies the impact of sensor censoring on the decision fusion performance when the number of sensors is unknown at the fusion center. The global decision rule adopted at the fusion center is the Chair-Varshney fusion rule modified to take account of the unknown network size...
Distributed antenna systems (DAS) are traditionally deployed for the coverage purpose, where multiple antennas connected with a common source are geographically separated within the cell. In order to provide high rate services in the 4G wireless system, DAS should be further enhanced with the help of advanced MIMO techniques. In this paper, we start with reviewing the typical scenarios for DAS, which...
In this paper, we analyze the error rate degradation caused by the finite-precision extrinsic log-likelihood ratio (LLR), i.e., demapper output, for multiple-input multiple-output (MIMO) bit-interleaved coded modulation with iterative decoding (BICM-ID). A closed-form expression for the probability density function (pdf) of the metric difference with finite precision is derived. This pdf is well-approximated...
Multiuser diversity is achieved by maximum C/I scheduler in both fast and slow fading scenarios. However, fairness among multiple users is not guaranteed in slow fading channel because time and frequency resource are always occupied by the user with largest signal to interference and noise ratio(SINR). Opportunistic beamforming using dumb antennas is a multiple antennas transmit technique to increase...
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