International Journal of Antennas and Propagation http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Source Geolocation in Urban Environments Using Multipath Fingerprinting Thu, 16 Apr 2015 10:46:07 +0000 http://www.hindawi.com/journals/ijap/2015/453157/ A method for determining the location of Global Systems for Mobile Communications (GSM) mobile transmitters is proposed. Our approach estimates the location of a source without the use of multilateration or Line-of-Sight (LOS) techniques. A Multipath Characteristic Database (MCD) containing the multipath feature vectors, for each possible transmitter location within an area of interest, is populated via ray-tracing software simulations. The multipath characteristics of interest are angle-of-arrival (AOA) (azimuth) and time-of-arrival (TOA). By minimizing the “distance” between estimated and simulated multipath feature vectors, an estimate for the actual source location can be obtained. The development of the estimation method is presented, followed by a detailed analysis of its estimation accuracy. Since the proposed method utilizes a simulated multipath signature database based upon the knowledge of the environment and the terrain, the need for a priori soundings from the area of interest is eliminated, thus making this location estimation system suitable for application in denied territories. Location accuracies compare favorably with the requirements for the location of wireless 9-1-1 callers as recommended by the Federal Communications Commission (FCC). Ram M. Narayanan, Brian R. Phelan, and Erik H. Lenzing Copyright © 2015 Ram M. Narayanan et al. All rights reserved. A Broadband Single-Feed Circularly Polarized Patch Antenna with Wide Beamwidth Thu, 09 Apr 2015 14:19:50 +0000 http://www.hindawi.com/journals/ijap/2015/740274/ A broadband single-feed circularly polarized patch antenna with wide beamwidth is presented. The patch is coupled to four asymmetric cross slots via a microstrip ring with eight matching segments underneath the ground plane, traversing through the arms of the cross slots in a serial manner. And a coupling slice instead of a resistive load is used as matching load of the microstrip ring for higher gain. Furthermore, a metal side wall surrounding the antenna is used to improve the isolation between adjacent elements in an array. Through optimizing the four asymmetric cross slots and eight matching segments, excellent performances are achieved by the proposed antenna, especially for the broadband and wide beamwidth. Measurement results show that the antenna has −10 dB reflection coefficient bandwidth of 29.7%, 3-dB axial-ratio bandwidth of 21.6%, and beamwidth of more than 90°. It can be considered as a good candidate for the element of arrays. Changhong Zhang, Junping Geng, Bin Zhou, Xianling Liang, and Ronghong Jin Copyright © 2015 Changhong Zhang et al. All rights reserved. Design of Fixed Beamformers Based on Vector-Sensor Arrays Thu, 09 Apr 2015 12:24:48 +0000 http://www.hindawi.com/journals/ijap/2015/181937/ Vector-sensor arrays such as those composed of crossed dipole pairs are used as they can account for a signal’s polarisation in addition to the usual direction of arrival information, hence allowing expanded capacity of the system. The problem of designing fixed beamformers based on such an array, with a quaternionic signal model, is considered in this paper. Firstly, we consider the problem of designing the weight coefficients for a fixed set of vector-sensor locations. This can be achieved by minimising the sidelobe levels while keeping a unitary response for the main lobe. The second problem is then how to find a sparse set of sensor locations which can be efficiently used to implement a fixed beamformer. We propose solving this problem by converting the traditional norm minimisation associated with compressive sensing into a modified norm minimisation which simultaneously minimises all four parts of the quaternionic weight coefficients. Further improvements can be made in terms of sparsity by converting the problem into a series of iteratively solved reweighted minimisations, as well as being able to enforce a minimum spacing between active sensor locations. Design examples are provided to verify the effectiveness of the proposed design methods. Matthew Hawes and Wei Liu Copyright © 2015 Matthew Hawes and Wei Liu. All rights reserved. Discussion on Reciprocity, Unitary Matrix, and Lossless Multiple Beam Forming Networks Thu, 09 Apr 2015 06:11:19 +0000 http://www.hindawi.com/journals/ijap/2015/946289/ The Lorentz reciprocity theorem enables us to establish that the transmitting and receiving patterns of any antenna are identical, provided some hypotheses on this antenna and the surrounding medium are satisfied. But reciprocity does not mean that the antenna behaves the same in the transmitting and the receiving modes. In this paper, array antennas fed by multiple beam forming networks are discussed, highlighting the possibility to have different values of internal losses in the beam forming network depending on the operation mode. In particular, a mathematical condition is derived for the specific case of a multiple beam forming network with lossless transmitting mode and lossy receiving mode, such a behavior being fully consistent with the reciprocity theorem. A theoretical discussion is provided, starting from a simple 2-element array to a general multiple beam forming network. A more practical example is then given, discussing a specific Nolen matrix design and comparing theoretical aspects with simulation results. Nelson Jorge G. Fonseca Copyright © 2015 Nelson Jorge G. Fonseca. All rights reserved. Applications of Generalized Cascade Scattering Matrix on the Microwave Circuits and Antenna Arrays Wed, 08 Apr 2015 09:31:22 +0000 http://www.hindawi.com/journals/ijap/2015/759439/ The ideal lossless symmetrical reciprocal network (ILSRN) is constructed and introduced to resolve the complex interconnections of two arbitrary microwave networks. By inserting the ILSRNs, the complex interconnections can be converted into the standard one-by-one case without changing the characteristics of the previous microwave networks. Based on the algorithm of the generalized cascade scattering matrix, a useful derivation on the excitation coefficients of antenna arrays is firstly proposed with consideration of the coupling effects. And then, the proposed techniques are applied on the microwave circuits and antenna arrays. Firstly, an improved magic-T is optimized, fabricated, and measured. Compared with the existing results, the prototype has a wider bandwidth, lower insertion loss, better return loss, isolation, and imbalances. Secondly, two typical linear waveguide slotted arrays are designed. Both the radiation patterns and scattering parameters at the input ports agree well with the desired goals. Finally, the feeding network of a two-element microstrip antenna array is optimized to decrease the mismatch at the input port, and a good impedance matching is successfully achieved. Shun-Feng Cao, Yong-Chang Jiao, and Zheng Zhang Copyright © 2015 Shun-Feng Cao et al. All rights reserved. Fourier Rotman Lens Enabled Directional Modulation Transmitter Wed, 08 Apr 2015 07:14:28 +0000 http://www.hindawi.com/journals/ijap/2015/285986/ A 10 GHz Fourier Rotman lens enabled dynamic directional modulation (DM) transmitter is experimentally evaluated. Bit error rate (BER) performance is obtained via real-time data transmission. It is shown that Fourier Rotman DM functionality enhances system security performance in terms of narrower decodable low BER region and higher BER values associated with BER sidelobes especially under high signal to noise ratio (SNR) scenarios. This enhancement is achieved by controlled corruption of constellation diagrams in IQ space by orthogonal injection of interference. Furthermore, the paper gives the first report of a functional dual-beam DM transmitter, which has the capability of simultaneously projecting two independent data streams into two different spatial directions while simultaneously scrambling the information signals along all other directions. Yuan Ding, Yunhua Zhang, and Vincent Fusco Copyright © 2015 Yuan Ding et al. All rights reserved. Optimization Framework and Parameter Determination for Proximity-Based Device Discovery in D2D Communication Systems Tue, 07 Apr 2015 13:04:39 +0000 http://www.hindawi.com/journals/ijap/2015/102049/ One of the most important processes in device-to-device communications of cellular devices is that of discovery, which determines the proximity of devices. When a discovery process is performed, there are several parameters to determine, including the discovery range, the discovery period, and the modulation and coding scheme of the discovery messages. In this paper, we address the relationships between these parameters and describe an optimization framework to determine them. In the proposed procedure, it is important to first optimize the discovery rate, which is defined as the number of discoverable devices per unit time. Once the discovery rate is maximized, the discovery period can be determined accordingly based on the device density and the target discovery range. Since the discovery rate is not affected by many of discovery parameters such as the discovery range, the device density, and the discovery period, it can be used as a performance metric for comparing discovery schemes with different discovery ranges or different discovery periods. Minjoong Rim, Seungyeob Chae, and Chung G. Kang Copyright © 2015 Minjoong Rim et al. All rights reserved. Effects of Reentry Plasma Sheath on Mutual-Coupling Property of Array Antenna Tue, 07 Apr 2015 13:01:27 +0000 http://www.hindawi.com/journals/ijap/2015/542392/ A plasma sheath enveloping a reentry vehicle would cause the failure of on-board antennas, which is an important effect that contributes to the “blackout” problem. The method of replacing the on-board single antenna with the array antennas and using beamforming technology has been proposed to mitigate “blackout” problem by many other researchers. Because the plasma sheath is a reflective medium, plasma will alter the mutual coupling between array elements and degrade the beamforming performance of array antenna. In this paper, the effects of the plasma sheath on the mutual coupling properties between adjacent array elements are studied utilizing the algorithm of finite integration technique. Results show that mutual coupling coefficients of array elements are deteriorating more seriously with the decrease of collision frequency. Moreover, when electron density and collision frequency are both large, plasma sheath improves the mutual coupling property of array elements; this conclusion suggests that replacing the on-board single antenna with the array antennas and using beamforming technology can be adopted to mitigate the blackout problem in this condition. B. W. Bai, X. P. Li, Y. M. Liu, and J. Xu Copyright © 2015 B. W. Bai et al. All rights reserved. Scan Performance and Reconfigurability of Agile Radiating Matrix Antenna Prototype Tue, 07 Apr 2015 12:56:44 +0000 http://www.hindawi.com/journals/ijap/2015/169303/ This paper is dedicated to different experimental validations concerning a novel concept of beam forming and beam steering antenna. The working principle of the antenna is based on the equivalent radiating surface approach and inspired from an electromagnetic band gap antenna. The theoretical aspect and some numerical validations have been already published in the work of Abou Taam et al. (2014). Different electromagnetic behaviors have been demonstrated, such as low mutual coupling, and high gain preservation for high scanning angles values. In this paper, some of these electromagnetic behaviors will be proven experimentally by the means of two different feeding configurations. H. Abou Taam, G. Zakka El Nashef, M. Salah Toubet, E. Arnaud, B. Jecko, T. Monediere, and M. Rammal Copyright © 2015 H. Abou Taam et al. All rights reserved. The Simulation and Experiment of a Non-Cross-Feeding Printed Log-Periodic Antenna Tue, 07 Apr 2015 12:56:07 +0000 http://www.hindawi.com/journals/ijap/2015/783405/ A non-cross-fed printed log-periodic antenna is simulated and studied experimentally. To avoid complex feeding with long coaxial line, the non-cross-feeding structure is applied in this antenna. The software CST Microwave Studio is employed to simulate the proposed antenna, and the optimized antenna model is obtained. According to the simulation results, the antenna prototype is produced and measured. Simulation and measured results show that the antenna is with  dB in band of 4.2–9.2 GHz. And the radiation pattern and gain vary steadily in this band, which achieves requirements for wideband antenna. This antenna design can be extended to the design of the antenna integrated in communication circuit. Chun-Ying Kang, Shu Lin, Zhi-Hua Zhao, and Li-Wen Jing Copyright © 2015 Chun-Ying Kang et al. All rights reserved. Design of a Novel UWB Omnidirectional Antenna Using Particle Swarm Optimization Tue, 07 Apr 2015 12:49:53 +0000 http://www.hindawi.com/journals/ijap/2015/303195/ A UWB E-plane omnidirectional microwave antenna is designed and fabricated for IEEE 802.11a communication system and microwave magnetron source system as a radiation monitor. A cooptimization method based on particle swarm optimization (PSO) algorithm and FDTD software is presented. The presented PSO algorithm is useful in many industrial microwave applications, such as microwave magnetron design and other techniques with a high power level. The maximum measured relative bandwidth of 65% is achieved for the proposed antenna after a rapid and efficient optimization. Furthermore, the measured antenna polarization purity reaches about 20 dB at the communication C band. The PSO algorithm is a powerful candidate for microwave passive component design. Chengyang Yu, Tanghong Xu, and Changjun Liu Copyright © 2015 Chengyang Yu et al. All rights reserved. Pattern Nulling of Linear Antenna Arrays Using Backtracking Search Optimization Algorithm Sun, 05 Apr 2015 12:30:51 +0000 http://www.hindawi.com/journals/ijap/2015/713080/ An evolutionary method based on backtracking search optimization algorithm (BSA) is proposed for linear antenna array pattern synthesis with prescribed nulls at interference directions. Pattern nulling is obtained by controlling only the amplitude, position, and phase of the antenna array elements. BSA is an innovative metaheuristic technique based on an iterative process. Various numerical examples of linear array patterns with the prescribed single, multiple, and wide nulls are given to illustrate the performance and flexibility of BSA. The results obtained by BSA are compared with the results of the following seventeen algorithms: particle swarm optimization (PSO), genetic algorithm (GA), modified touring ant colony algorithm (MTACO), quadratic programming method (QPM), bacterial foraging algorithm (BFA), bees algorithm (BA), clonal selection algorithm (CLONALG), plant growth simulation algorithm (PGSA), tabu search algorithm (TSA), memetic algorithm (MA), nondominated sorting GA-2 (NSGA-2), multiobjective differential evolution (MODE), decomposition with differential evolution (MOEA/D-DE), comprehensive learning PSO (CLPSO), harmony search algorithm (HSA), seeker optimization algorithm (SOA), and mean variance mapping optimization (MVMO). The simulation results show that the linear antenna array synthesis using BSA provides low side-lobe levels and deep null levels. Kerim Guney and Ali Durmus Copyright © 2015 Kerim Guney and Ali Durmus. All rights reserved. Estimation of Sidelobe Level Variations of Phased Codes in Presence of Random Interference for Bistatic Wideband Noise Radar Sun, 05 Apr 2015 10:17:01 +0000 http://www.hindawi.com/journals/ijap/2015/297823/ We discuss the importance of using the sidelobe level of the cross-correlation function as a criterion to implement a noise radar based on the transmission of wideband binary waveforms. Theoretical expressions are introduced for the parameters Peak-Sidelobe, Secondary-Sidelobe, and Integrated-Sidelobe levels for both Golay and pseudorandom binary sequences in presence of additive white Gaussian noise, relating the sequence length to the spectral power of the interfering noise. These expressions offer a valuable method for adaptive radar waveform design in order to determine sequence requirements which allow facing the noise present in the frequency band of interest. We also show a comparison of the ambiguity functions for Golay and PRBS sequences to analyze their performance in terms of Doppler and range accuracy. We describe a practical implementation of a pseudonoise waveform-based bistatic radar with reduced sidelobe level due to the use of Golay codes in combination with single side band modulation and operation at UHF band. Experimental measurements were performed in actual scenarios for ranging test of single and double targets. Linear polarizations were combined with different length sequences to determine their influence on the sounder performance under field test conditions. Ana Vazquez Alejos, Muhammad Dawood, and Habeeb Ur-Rahman Mohammed Copyright © 2015 Ana Vazquez Alejos et al. All rights reserved. Statistical Analysis of Radio Propagation Channel in Ruins Environment Wed, 01 Apr 2015 06:59:23 +0000 http://www.hindawi.com/journals/ijap/2015/173936/ The cellphone based localization system for search and rescue in complex high density ruins has attracted a great interest in recent years, where the radio channel characteristics are critical for design and development of such a system. This paper presents a spatial smoothing estimation via rotational invariance technique (SS-ESPRIT) for radio channel characterization of high density ruins. The radio propagations at three typical mobile communication bands (0.9, 1.8, and 2 GHz) are investigated in two different scenarios. Channel parameters, such as arrival time, delays, and complex amplitudes, are statistically analyzed. Furthermore, a channel simulator is built based on these statistics. By comparison analysis of average excess delay and delay spread, the validation results show a good agreement between the measurements and channel modeling results. Jiao He, Er-Ping Li, Sai-Qiong Zhou, and Kun Liao Copyright © 2015 Jiao He et al. All rights reserved. A Compact MultiBand and Dual-Polarized Mobile Base-Station Antenna Using Optimal Array Structure Mon, 30 Mar 2015 13:49:12 +0000 http://www.hindawi.com/journals/ijap/2015/178245/ This paper introduces a multiband base-station antenna to provide multiple communications services. There is growing need for multiband base-station antennas for mobile communications to serve existing 2nd and 3rd generation systems and to provide emerging 4th generation communication service as well as WiFi. For example, cellular, PCS, and especially WCDMA service are currently widely used in Korea, and 4th generation service (WiBro and LTE), introduced in 2011, will have to operate in parallel with existing services. The proposed multiband base-station antenna can provide a single/dual/triple or more multiple services using dual-polarization (±45° linear polarizations) according to the requirements of the service provider. This antenna has a shared aperture, having several array antenna sets for multiple services (Band 1: cellular service in 0.824~0.894 GHz, Band 2: PCS, WCDMA, and WiFi in 1.920~2.170 GHz, Band 3: WiBro and WiMAX in 2.300~2.400 GHz, and Band 4: WiMAX in 5.150~5.850 GHz). This antenna can be helpful for reducing base-station operating expenses and to create a clean urban landscape by minimizing the number of base-station antennas, which are increasing rapidly. Young-Bae Jung and Soon-Young Eom Copyright © 2015 Young-Bae Jung and Soon-Young Eom. All rights reserved. Codesign of Beam Pattern and Sparse Frequency Waveforms for MIMO Radar Mon, 30 Mar 2015 09:00:39 +0000 http://www.hindawi.com/journals/ijap/2015/563941/ Multiple-input multiple-output (MIMO) radar takes the advantages of high degrees of freedom for beam pattern design and waveform optimization, because each antenna in centralized MIMO radar system can transmit different signal waveforms. When continuous band is divided into several pieces, sparse frequency radar waveforms play an important role due to the special pattern of the sparse spectrum. In this paper, we start from the covariance matrix of the transmitted waveform and extend the concept of sparse frequency design to the study of MIMO radar beam pattern. With this idea in mind, we first solve the problem of semidefinite constraint by optimization tools and get the desired covariance matrix of the ideal beam pattern. Then, we use the acquired covariance matrix and generalize the objective function by adding the constraint of both constant modulus of the signals and corresponding spectrum. Finally, we solve the objective function by the cyclic algorithm and obtain the sparse frequency MIMO radar waveforms with desired beam pattern. The simulation results verify the effectiveness of this method. Chaoyun Mai, Songtao Lu, Jinping Sun, and Guohua Wang Copyright © 2015 Chaoyun Mai et al. All rights reserved. Advances in Statistical Channel Modeling for Wireless Communications Tue, 24 Mar 2015 07:41:57 +0000 http://www.hindawi.com/journals/ijap/2015/541619/ José F. Paris, Paschalis C. Sofotasios, and Theodoros A. Tsiftsis Copyright © 2015 José F. Paris et al. All rights reserved. Enhancing the Efficiency and Accuracy of MLFMA-PO Hybrid Method for Analyzing Electrically Large Objects Mon, 23 Mar 2015 13:19:34 +0000 http://www.hindawi.com/journals/ijap/2015/826217/ An enhanced hybrid technique combining the multilevel fast multipole algorithm (MLFMA) and the physical optics (PO) is presented for analyzing scattering and radiation by electrically large structures. Based on the previously proposed hybrid technique, an extra octree structure is built for the moment method (MoM) region to accelerate the solving process and an iteration scheme is proposed to further enhance the efficiency compared to the conventional hybrid method. What is more, the modified iterative physical optics (IPO) accelerated by MLFMA technique is adopted to improve the accuracy by simulating complex structures with strong reflections. Numerical results are given to demonstrate the improved accuracy and higher accuracy of the proposed hybrid technique compared to the previous MLFMA-PO method. Hao Ding, Yong Zhang, and Hai Lin Copyright © 2015 Hao Ding et al. All rights reserved. Beamforming and Interference Cancellation in D2D Random Network Mon, 23 Mar 2015 12:27:08 +0000 http://www.hindawi.com/journals/ijap/2015/607563/ Device-to-Device (D2D) communication is an important proximity communication technology. We model the hybrid network of cellular and D2D communication with stochastic geometry theory. In the network, cellular base stations are deployed with multiantennas. Two transmission strategies including beamforming and interference cancellation are proposed to boost system achievable rate in this paper. We derive analytical success probability and rate expression in these strategies. In interference cancellation strategy, we propose the partical BS transmission degrees of freedom (dofs) that can be used to cancel its D2D users (DUEs) interferences around the BS or to boost the desired signal power of associated cellular (CUE). In order to maximize the total area spectral efficiency (ASE), the BS transmission degrees of freedom are allocated according to proper interference cancellation radius around the BS. Monte Carlo simulations are performed to verify our analytical results, and two transmission strategies are compared. Langtao Hu and Chaowei Yuan Copyright © 2015 Langtao Hu and Chaowei Yuan. All rights reserved. On the Effect of Different Grips of Handsets on Data Rate in the Measured Channels Mon, 23 Mar 2015 11:17:05 +0000 http://www.hindawi.com/journals/ijap/2015/593297/ The investigation on the achieved data rate of the cellular system considering different grips of handsets at different frequencies using measurement results of the measurement campaign—which was carried out in the city of Aalborg—is presented in this paper. The achieved data rate of the multiple-input single-output (MISO) interference channel is investigated. A typical propagation environment using two BSs and four handsets, like smart phones, held by four to eight different users was designed and multiple-input multiple-output (MIMO) channels in different scenarios were measured. In this paper, two BSs and two handsets at each measurement time are considered. The impact of the different parameters like correlation, different grips of handsets, and different long term evolution (LTE) frequency bands on the achieved data rate is investigated for different measurements. It could be concluded that the variations in the values of data rate are weakly associated with the different grips of handsets but more correlated with different frequencies. Maryam Rahimi and Ehsan Foroozanfard Copyright © 2015 Maryam Rahimi and Ehsan Foroozanfard. All rights reserved. On the Efficient Generation of -- and -- White Samples with Applications Sun, 22 Mar 2015 13:40:01 +0000 http://www.hindawi.com/journals/ijap/2015/873890/ This paper is concerned with a simple and highly efficient random sequence generator for uncorrelated and variates. The algorithm may yield an efficiency of almost 100%, and this high efficiency can be reached for all special cases such as ,  ,   , Nakagami-m, Nakagami-q, Weibull, Hoyt, Rayleigh, Rice, Exponential, and the One-Sided Gaussian. This generator is implemented via the rejection technique and allows for arbitrary fading parameters. The goodness-of-fit is measured using the Kolmogorov-Smirnov and Anderson-Darling tests. The maximum likelihood parameter estimation for the distribution is proposed and verified against true values of the parameters chosen in the generator. We also provide two important applications for the random sequence generator, the first one dealing with the performance assessment of a digital communication system over the and fading channels and the second one dealing with the performance assessment of the spectrum sensing with energy detection over special cases of these channels. Theoretical and simulation results are compared, validating again the accuracy of the generators. Rausley Adriano Amaral de Souza, Antonio Marcelo Oliveira Ribeiro, and Dayan Adionel Guimarães Copyright © 2015 Rausley Adriano Amaral de Souza et al. All rights reserved. Propagation Measurement on Earth-Sky Signal Effects for High Speed Train Satellite Channel in Tropical Region at Ku-Band Sun, 22 Mar 2015 11:31:31 +0000 http://www.hindawi.com/journals/ijap/2015/270949/ Recent advances in satellite communication technologies in the tropical regions have led to significant increase in the demand for services and applications that require high channel quality for mobile satellite terminals. Determination and quantification of these requirements are important to optimize service quality, particularly in the Malaysian region. Moreover, the tests on current satellite propagation models were carried out at temperate regions whose environmental characteristics are much different from those in Malaysia. This difference renders these propagation models inapplicable and irrelevant to tropical regions in general. This paper presents the link characteristics observations and performance analysis with propagation measurements done in tropical region to provide an accurate database regarding rain and power arches supply (PAs) attenuations in the tropics for mobile scenarios. Hence, an extension for improving the performance assessment and analysis of satellite/transmission has been achieved. The Malaysia propagation measurement for mobile scenario (Malaysia-PMMS) enables first-hand coarse estimation and attenuation analysis, because the attenuation resulting from rain and PAs becomes easily amenable for measurement. Parallel to that, the measured attenuation has been compared with that of the simulated output at noise floor level. The underlying analytical tool is validated by measurements specific at tropical region, for dynamic model of mobile satellite links operating at higher than 10 GHz. Abdulmajeed H. J. Al-Jumaily, A. Sali, J. S. Mandeep, and Alyani Ismail Copyright © 2015 Abdulmajeed H. J. Al-Jumaily et al. All rights reserved. Modeling of the Land Mobile Satellite Channel considering the Terminal’s Driving Direction Sun, 22 Mar 2015 09:26:26 +0000 http://www.hindawi.com/journals/ijap/2015/372124/ A precise characterization of the Land Mobile Satellite (LMS) channel, that is, the channel between a satellite and a mobile terminal, is of crucial importance while designing a satellite-based communication system. State-of-the-art statistical LMS channel models offer the advantage of requiring only a few input parameters, which include the environment type and the elevation angle of the satellite. However, the azimuth angle relative to the driving direction of the mobile terminal is usually ignored, as its proper modeling requires either an extensive measurement campaign or a significant effort from the user, as a precise geometrical description of the scenario is required. In this contribution we show that the impact of the driving direction on the channel statistics is not negligible and requires to be modeled explicitly. Moreover, we propose a statistical LMS channel model whose parameters are obtained via an image-based state estimation method. The image-based method is verified by a comparison with measured radio frequency signal levels. The proposed method allows obtaining a complete statistical description of the channel for arbitrary elevation and azimuth angles. Marie Rieche, Alexander Ihlow, Daniel Arndt, Fernando Pérez-Fontán, and Giovanni Del Galdo Copyright © 2015 Marie Rieche et al. All rights reserved. Tracking- and Scintillation-Aware Channel Model for GEO Satellite to Land Mobile Terminals at Ku-Band Thu, 19 Mar 2015 16:30:45 +0000 http://www.hindawi.com/journals/ijap/2015/392714/ Recent advances in satellite to land mobile terminal services and technologies, which utilize high frequencies with directional antennas, have made the design of an appropriate model for land mobile satellite (LMS) channels a necessity. This paper presents LMS channel model at Ku-band with features that enhance accuracy, comprehensiveness, and reliability. The effect of satellite tracking loss at different mobile terminal speeds is considered for directional mobile antenna systems, a reliable tropospheric scintillation model for an LMS scenario at tropical and temperate regions is presented, and finally a new quality indicator module for different modulation and coding schemes is included. The proposed extended LMS channel (ELMSC) model is designed based on actual experimental measurements and can be applied to narrow- and wide-band signals at different regions and at different speeds and multichannel states. The proposed model exhibits lower root mean square error (RMSE) and significant performance observation compared with the conventional model in terms of the signal fluctuations, fade depth, signal-to-noise ratio (SNR), and quality indicators accompanied for several transmission schemes. Ali M. Al-Saegh, A. Sali, J. S. Mandeep, and Alyani Ismail Copyright © 2015 Ali M. Al-Saegh et al. All rights reserved. Key Considerations in the Modeling of Tropical Maritime Microwave Attenuations Thu, 19 Mar 2015 07:53:17 +0000 http://www.hindawi.com/journals/ijap/2015/246793/ This paper presents some key considerations for modeling of over-sea radio-wave propagations in 5 GHz band. The summarized information is based on a series of measurement campaigns which were recently carried out in the tropical maritime environments near Singapore. Multiray propagations and ducting of radio waves have been highlighted and considered in over-sea path loss modeling and prediction. It is noted that the sea-surface reflection is an important contribution in the received field, while the duct layers could enhance the radio-wave propagations. Our studies also show that the refracted ray inside evaporation duct could be a strong ray for short-range near sea-surface applications and needs to be properly evaluated. Yee Hui Lee and Yu Song Meng Copyright © 2015 Yee Hui Lee and Yu Song Meng. All rights reserved. Adaptive Beamforming Based on Compressed Sensing with Smoothed Norm Wed, 18 Mar 2015 14:36:56 +0000 http://www.hindawi.com/journals/ijap/2015/959856/ An adaptive beamforming based on compressed sensing with smoothed norm for large-scale sparse receiving array is proposed in this paper. Because of the spatial sparsity of the arriving signal, compressed sensing is applied to sample received signals with a sparse array and reduced channels. The signal of full array is reconstructed by using a compressed sensing reconstruction method based on smoothed norm. Then an iterative linearly constrained minimum variance beamforming algorithm is adopted to form antenna beam, whose main lobe is steered to the desired direction and nulls to the directions of interferences. Simulation results and Monte Carlo analysis for linear and planar arrays show that the beam performances of our proposed adaptive beamforming are similar to those of full array antenna. Yubing Han and Jian Wang Copyright © 2015 Yubing Han and Jian Wang. All rights reserved. Small Displacement Detection of Biological Signals Using the Cyclic Frequency Method Sun, 15 Mar 2015 09:40:22 +0000 http://www.hindawi.com/journals/ijap/2015/842123/ A new signal processing method called the Cyclic Frequency method is proposed for small displacement detection of vital signals such as heart rate and respiration using the CW radar method. We have presented experimental results of small displacement detection to confirm the validity of the method. The displacement amplitude 2.5 mm can be detected with a propagation frequency of 24.15 GHz. We may increase the propagation frequency for smaller displacement amplitude or target velocity. Dan Zhang, Masahiko Kurata, and Takayuki Inaba Copyright © 2015 Dan Zhang et al. All rights reserved. Outage-Constrained Beamforming for Two-Tier Massive MIMO Downlink with Pilot Reuse Thu, 12 Mar 2015 13:44:19 +0000 http://www.hindawi.com/journals/ijap/2015/840142/ Massive multiple-input multiple-output (MIMO) systems and small cell networks are both regarded as promising candidates to meet the exponential growth of mobile data traffic for the next generation (5G) wireless communications. Hence, a new kind of multitier networks which combine massive MIMO macro cells with a secondary tier of small cells is proposed to resolve the contradiction of large network coverage and high data rate. In such multitier networks, it is inevitable to allocate nonorthogonal uplink pilot sequences to user equipment (UE) due to the large number of users. We propose a pilot reuse scheme by exploiting the unique architecture of this networks and analyse the special mixed channel state information (CSI) yielded by the pilot reuse scheme. Based on the mixed CSI, we formulate a downlink transmit beamforming problem of minimizing the total power consumption while satisfying the quality of service (QoS) requirements with outage constraints. After decomposing the original problem into simpler subproblems, we provide an efficient algorithm to combine these subproblems and solve them iteratively for generating the beamforming vectors. Monte Carlo simulations show that the average power consumption of the proposed pilot reuse scheme and its associated beamforming algorithm is close to that of the perfect CSI case. Guozhen Xu, An Liu, Wei Jiang, Haige Xiang, and Wu Luo Copyright © 2015 Guozhen Xu et al. All rights reserved. Compact Wake-Up Module Design Based on an Energy-Harvesting Rectenna for Wireless Sensor Receivers Thu, 12 Mar 2015 11:06:46 +0000 http://www.hindawi.com/journals/ijap/2015/976875/ A new compact energy-harvesting module is proposed with compact design techniques. The rectifying circuit eliminates the band-pass filter and matching circuit, based on an active antenna concept and a direct matching technique. For exact circuit impedance, via holes are processed with precise fabrication techniques. The implemented circuit has achieved a circuit size reduction of 76.7%. The proposed system has been applied to a wireless wake-up receiver system with excellent operating performance. Sang-Min Han, Yongwan Lee, Taemin Choi, Seok-Jae Lee, Jung-Woo Baik, Jongsik Lim, and Dal Ahn Copyright © 2015 Sang-Min Han et al. All rights reserved. A Novel Multiband Miniature Planar Inverted F Antenna Design for Bluetooth and WLAN Applications Mon, 09 Mar 2015 06:49:36 +0000 http://www.hindawi.com/journals/ijap/2015/970152/ A novel compact planar inverted F antenna (PIFA) optimized using genetic algorithms for 2.4 GHz (Bluetooth) and 5 GHz (UNII-1, UNII-2, UNII-2 extended, and UNII-3) bands is presented. The patch with a shorting pin is on a  mm3 substrate, which is suspended in air 5 mm above a  mm2 ground plane. Genetic algorithm optimization (GAO) is used to optimize the patch geometry, feed position, and shorting pin position simultaneously. Simulations are carried out by using HFSS and a prototype antenna is fabricated to compare the measurements with the simulations. The antenna shows fractional impedance bandwidths of 4% and 21% and gains of 2.5 dB and 3.2 dB at lower and upper bands, respectively. J. M. Jeevani W. Jayasinghe and Disala Uduwawala Copyright © 2015 J. M. Jeevani W. Jayasinghe and Disala Uduwawala. All rights reserved.