OFDM/offset-QAM (OFDM/OQAM) has been proven to be a promising multi-carrier transmission technique. However, carrier frequency offset (CFO) can lead to severe inter-carrier interference (ICI) and performance degradation. Meanwhile, channel estimation is also an important issue because of the intrinsic characteristics of OFDM/OQAM. In this paper, a novel pilot structure and a frequency-domain cross-correlation algorithm are proposed for the joint CFO and channel estimation. Analysis and simulation results validate the effectiveness of the proposed pilot structure and estimation algorithm.

This letter considers problems with an efficient link layer multicasting technique in a wireless personal area network environment using a directional antenna. First, we propose an adaptive directional multicast scheme (ADMS) for delay-sensitive applications in mmWave WPAN with directional antenna. Second, the proposed ADMS aims to improve throughput as well as satisfy the application-specific delay requirements. We evaluate the performances of legacy Medium Access Control, Life Centric Approach, and adaptive directional multicast schemes via QualNet 5.0. Our results show that the proposed scheme provides better performance in terms of total network throughput, average transmission time, packet delivery ratio and decodable frame ratio.

Wireless broadcasting of heterogeneous XML data has become popular in many applications, where energy-efficient processing of user queries at the mobile client is a critical issue. This paper proposes a new index structure for wireless stream of heterogeneous XML data to enhance tuning time performance in processing path queries on the stream. The index called PrefixSummary stores for each location path in the XML data the address of a bucket in the stream which contains an XML node satisfying the location path and appearing first in the stream. We present algorithms to generate broadcast stream with the proposed index and to process a path query on the stream efficiently by exploiting the index. We also suggest a replication scheme of PrefixSummary within a broadcast cycle to reduce latency in query processing. By analysis and experiment we show the proposed PrefixSummary approach can reduce tuning time for processing path queries significantly while it can also achieve reasonable access time performance by means of replication of the index over the broadcast stream.

The fringe field effects of nano-electromechanical (NEM) nonvolatile memory cells have been investigated analytically for the accurate evaluation of NEM memory cells. As the beam width is scaled down, fringe field effect becomes more severe. It has been observed that pull-in, release and hysteresis voltage decrease more than our prediction. Also, the fringe field on cell characteristics has been discussed.

A gated sense amplifier (GSA) consisting of a low-Vt gated preamplifier (LGA) and a high-Vt sense amplifier (SA) is proposed. The gating scheme of the LGA enables quick amplification of an initial cell signal voltage (vS0) because of its low Vt and prevents the cell signal from degrading due to interference noise between data lines. As for a conventional sense amplifier (CSA), this new type of noise causes sensing error, and the noise-generation mechanism was clarified for the first time by analysis of vS0. The high-Vt SA holds the amplified signal and keeps subthreshold current low. Moreover, the gating scheme of the low-Vt MOSFETs in the LGA drives the I/O line quickly. The GSA thus simultaneously achieves fast sensing, low-leakage data holding, and fast I/O driving, even for sub-1-V mid-point sensing. The GSA is promising for future sub-1-V gigabit dynamic random-access memory (DRAM) because of reduced variations in the threshold voltage of MOSFETs; thus, the offset voltage of the LGA is reduced. The effectiveness of the GSA was verified with a 70-nm 512-Mbit DRAM chip. It demonstrated row access time (tRCD) of 16.4 ns and read access (tAA) of 14.3 ns at array voltage of 0.9 V.

We propose a network coordinated opportunistic beamforming (NC-OBF) protocol for downlink K-cell networks with M-antenna base stations (BSs). In the NC-OBF scheme, based on pseudo-randomly generated BF vectors, a user scheduling strategy is introduced, where each BS opportunistically selects a set of mobile stations (MSs) whose desired signals generate the minimum interference to the other MSs. Its performance is then analyzed in terms of degrees-of-freedom (DoFs). As our achievability result, it is shown that KM DoFs are achievable if the number N of MSs in a cell scales at least as SNRKM-1, where SNR denotes the received signal-to-noise ratio. Furthermore, by deriving the corresponding upper bound on the DoFs, it is shown that the NC-OBF scheme is DoF-optimal. Note that the proposed scheme does not require the global channel state information and dimension expansion, thereby resulting in easier implementation.

We present an economical and fault-tolerant load balancing strategy (EFTLBS) based on an operator replication mechanism and a load shedding method, that fully utilizes the network resources to realize continuous and highly-available data stream processing without dynamic operator migration over wide area networks. In this paper, we first design an economical operator distribution (EOD) plan based on a bin-packing model under the constraints of each stream bandwidth as well as each server's CPU capacity. Next, we devise super-operator (SO) that load balances multi-degree operator replicas. Moreover, for improving the fault-tolerance of the system, we color the SOs based on a coloring bin-packing (CBP) model that assigns peer operator replicas to different servers. To minimize the effects of input rate bursts upon the system, we take advantage of a load shedding method while keeping the QoS guarantees made by the system based on the SO scheme and the CBP model. Finally, we substantiate the utility of our work through experiments on ns-3.

This paper considers the power allocation (PA) problem for three-node decode-and-forward (DF) relay communication systems, where the aggregate transmit power constraint is imposed on the source and the relay and the optimization target is to maximize the system's instantaneous information rate. Since the relay is equipped with multiple antennas, the receiver and transmitter beamforming strategies are generally adopted. In this paper, we start by proposing a closed-form solution for the frequency-flat (FF) fading environment, then give a bisection algorithm with low complexity to obtain an optimal solution for the frequency-selective (FS) fading scenario. Finally, simulations validate the proposed methods.

We propose a novel 13 planar optical switch using aspheric lenses and carrier-induced tunable prisms on InP. An input light beam is collimated by the aspheric lenses in a slab waveguide. The tunable prism, whose refractive indices are tuned by the carrier plasma effect, deflect the collimated light beam and guide it to the output ports. The switching operations of the 13 optical switch that consists of five lenses and eight prisms with a footprint of 5003500 µm are performed by three-dimensional beam propagation methods. A static switching operation with a 5-dB insertion loss and a 13-dB extinction ratio is obtained with 70-mA current injection for each prism. This device has a simple structure and low power consumption and may be useful for optical packet switching systems.

The peer-assisted streaming paradigm has been widely employed to distribute live video data on the internet recently. In general, the mesh-based pull approach is more robust and efficient than the tree-based push approach. However, pull protocol brings about longer streaming delay, which is caused by the handshaking process of advertising buffer map message, sending request message and scheduling of the data block. In this paper, we propose a new approach, mesh-push, to address this issue. Different from the traditional pull approach, mesh-push implements block scheduling algorithm at sender side, where the block transmission is initiated by the sender rather than by the receiver. We first formulate the optimal upload bandwidth utilization problem, then present the mesh-push approach, in which a token protocol is designed to avoid block redundancy; a min-cost flow model is employed to derive the optimal scheduling for the push peer; and a push peer selection algorithm is introduced to reduce control overhead. Finally, we evaluate mesh-push through simulation, the results of which show mesh-push outperforms the pull scheduling in streaming delay, and achieves comparable delivery ratio at the same time.

We investigated optical transmission characteristics of aluminum thin films with periodic hole arrays in sub-wavelength. We divided white light into several color spectra using a color filter based on the surface plasmon resonance (SPR) utilizing aluminum showing high plasma frequency. By optimizing a hole-array period, hole shape, polarization and index difference of two surface, transmittance of 30% and full-width at half-maximum of around 100 nm were achieved.

Beamforming with sparse constraint has shown significant performance improvement. In this letter, a least squares constant modulus blind adaptive beamforming with sparse constraint is proposed. Simulation results indicate that the proposed approach exhibits better performance than the well-known least squares constant modulus algorithm (LSCMA).

The problem of a Gaussian beam that is incident on a plane dielectric interface from a denser dielectric medium to a rarer one and is reflected at the interface has been important research subjects studied by many researchers. In this paper, we have obtained a novel uniform asymptotic solution for reflection and beam shift of the Gaussian beam that is incident on the interface from the denser medium. The uniform asymptotic solution consists of the geometrically reflected beam, the lateral beam if any, and the newly derived transition beam which plays an important role in the transition region near the critical angle of the total reflection. We have confirmed the validity of the uniform asymptotic solution by comparing with the reference solution obtained numerically from the integral representation. We have shown that, in addition to the Goos-Hanchen shift and the angular shift, the Gaussian beam is shifted to either direction by the interference of the geometrically reflected beam and the lateral beam near the critical angle of the total reflection.

This paper proposes a differential fault analysis on the stream cipher MUGI, which uses two kinds of update functions of an intermediate state. MUGI was proposed by Hitachi, Ltd. in 2002 and is specified as ISO/IEC 18033-4 for keystream generation. Differential fault analysis (DFA) is a type of fault analysis, which is considered to be a serious threat against secure devices such as smart cards. DFA on MUGI was first proposed at ICISC 2010 [25]; however, the attack condition for the successful attack such as the position into which the fault is injected was restricted. In this paper, we extend the attack methods which are more practical, based on a one-byte and a multi-byte fault models using the relationship between two kinds of update functions that are mutually dependent. In the proposed attack, the attacker can know the position affected by the fault injection even if he has no control of the timing of the fault injection. As a result, a 128-bit secret key can be recovered using 13 pairs of correct and faulty outputs on average.

Based on Tu-Deng's conjecture and the Tu-Deng function, in 2010, X. Tang et al. proposed a class of Boolean functions in even variables with optimal algebraic degree, very high nonlinearity and optimal algebraic immunity. In this corresponding, we consider the concatenation of Tang's function and another Boolean function, and study its cryptographic properties. With this idea, we propose a class of 1-resilient Boolean functions in odd variables with optimal algebraic degree, good nonlinearity and suboptimal algebraic immunity based on Tu-Deng's conjecture.

We address a problem of sampling and reconstructing periodic piecewise polynomials based on the theory for signals with a finite rate of innovation (FRI signals) from samples acquired by a sinc kernel. This problem was discussed in a previous paper. There was, however, an error in a condition about the sinc kernel. Further, even though the signal is represented by parameters, these explicit values are not obtained. Hence, in this paper, we provide a correct condition for the sinc kernel and show the procedure. The point is that, though a periodic piecewise polynomial of degree R is defined as a signal mapped to a periodic stream of differentiated Diracs by R + 1 time differentiation, the mapping is not one-to-one. Therefore, to recover the stream is not sufficient to reconstruct the original signal. To solve this problem, we use the average of the target signal, which is available because of the sinc sampling. Simulation results show the correctness of our reconstruction procedure. We also show a sampling theorem for FRI signals with derivatives of a generic known function.

In multi-cell wireless systems with insufficient frequency reuse, the downlink transmission suffers from other cell interference (OCI). The cooperative transmission among multiple base stations is an effective way to mitigate OCI and increase the system sum rate. An adaptive scheme for serving one user in each cell was proposed in [1]. In this paper, we generalize the scheme in [1] by serving more than one user in each cell with adaptive OCI cancelation. Based on our derived statistics of a user for different transmission strategies, we propose a low complexity transmission scheme that achieves near-maximal ergodic sum rate. Through numerical examples, we show that the system sum rate can be improved by selecting the appropriate transmission strategy combination adaptively. As a result, our proposed system can explore spatial multiplexing gain without additional power and thus improves the system sum rate significantly.

In this paper, a distributed cooperative multicell beamforming algorithm is proposed, and a detail analysis and solving method for instantaneous and statistical channel state information (CSI) are presented. Firstly, an improved distributed iterative beamforming algorithm is proposed for the multiple-input single-output interference channel (MISO IC) scenario which chooses virtual signal-to-interference-and-noise (SINR) as decision criterion to initialize and then iteratively solves the constrained optimization problem of maximizing the virtual SINR for a given level of generated interference to other users. Then, the algorithm is generalized to the multicell date sharing scenario with a heuristics power allocation scheme based on a viewpoint of the layered channel. Finally, the performance is illustrated through numerical simulations.

In this paper, we propose new constructions of binary sequences based on an interleaving technique. In our constructions, we make use of any binary sequences with ideal 2-level autocorrelation, a special shift sequence as well as the perfect binary sequence or sequence (0,1,1) in the interleaved structure to get the new sequences. Except for the most autocorrelation values of our new sequences, we find that the unexpected autocorrelation values only occur four or two times in each period no matter how long the period is. We state that the sequences have a good autocorrelation in this case. In particular, the autocorrelation distribution of our sequences is determined.

This paper proposes an open loop beamforming scheme for downlink multiuser multiple-input multiple-output (MIMO) transmissions in frequency division duplex (FDD). The proposed scheme uses the uplink direction of arrival (DOA) estimation, and then generates the beamforming weight such that the interference caused by the overlapping beams is removed by applying the dirty-paper coding (DPC) principle. The simulation results show that the proposed scheme provides the gain of 32.3% at minimum in terms of the spectral efficiency at the CDF of 50% compared to the conventional DOA based beamforming scheme. In addition, it is shown that the proposed scheme has superior performance to closed loop scheme with the limited feedback information.