Low-power low-profile multifunction helmet-mounted smart array antenna

The use of smart or adaptive array antennas has attracted considerable interest in the mobile communications community. We investigate the combined use of an adaptive/smart array antenna and Rake receiver (space-time processing) to jointly mitigate the effect of multiple access interference (MAI) and multipath fading in a CDMA system, while taking angle spread into account. We provide simulation results concerning mean bit error rate (BER) performance of such a system for different numbers of antenna elements, numbers of users and angle spreads. The obtained results show that the investigated smart antenna system can effectively combat adverse MAI and fading effects and improve the CDMA system performance.

Cross-layer optimization for wireless mesh networks with smart antennas

Smart antenna techniques at the base station can dramatically improve the performance of the mobile radio system by employing spatial filtering. The design of a fully spatial signal processor using rectangular array configuration, is proposed in this paper. Two-dimensional (2-D) spatial filters that can be implemented by microstrip technology are capable of filtering the received signal in the angular domain as well as the frequency domain. Furthermore, it has wideband properties and, hence, eliminates the requirement, of different antenna, spacing for applications including various carrier frequencies. The desired frequency selectivity of the smart antenna can be combined with compensation of the undesired frequency performance of a single antenna element, and the result is quite satisfactory for practical implementation. In addition, if the elements of the array are not perfectly onmidirectional or frequency independent, we can compensate for these deficiencies in the design algorithm. Two different algorithms for calculating the real-valued weights of the antenna elements are proposed. The first algorithm is more complex but leads to sharper beams and controlled performance. The second method is simpler but has wider beam and lower fractional bandwidth. Some computer simulation results demonstrating the directional beam patterns of the designed beamformers are presented at the end of this paper.

Smart antennas techniques are considered to be the best means to mitigate the effects of severe and dynamic interference on the performance of modern communication systems. But in a practical array system, the receiving elements of the smart array must be of some physical size. The elements receive and re-radiate the incident signals, which results in the mutual coupling among them. The mutual coupling distorts the linear phase front of the incoming signal which results in an inaccurate DOA estimation and significant degradation of the system performance. Therefore, any practical implementation of smart antenna systems requires compensation for mutual coupling effect in smart antennas.

The paper investigates the capacity improvement for CDMA wireless communication systems with base-station antenna array. We model the effects of Rayleigh fading, log-normal shadowing, multiple access interference, multi-tier cells, directional beam and thermal noise. Analytical results and computer simulations show that smart antenna at the base station can dramatically improve the reverse channel performance of multicell CDMA wireless systems. The paper also discuss the effects of using directional antennas at the user terminals. System capacity under a multipath environment is considered and simulated at the same time.

According to several research circles, it is predicted that future wireless systems that employ smart antenna techniques would be more effective at using available spectrum and at building new networks at lower cost, while also improving service quality and allowing for cross-technology operation. These systems require constant monitoring in order to function properly, allowing users to apply machine learning algorithms to analyse large amounts of data from various antenna settings. Machine learning is a technique in which a machine learns and improves on its own, based on past data. These techniques enable the smart antenna target to be learned in an efficient, reliable, and adaptive manner. In this paper, the antenna array and antenna developed for the Internet of Things applications were highlighted. In this paper, we review how machine learning techniques can handle these applications effectively and what the concept of adaptive antenna is and when it can be used in this day and age characterized by the rapid development of information technology.

We introduce a novel merger of direct sequence code division multiple access (DS-CDMA) and smart antenna arrays. With regard to the DS-CDMA scheme, we employ carrier interferometry DS-CDMA (CI/DS-CDMA), a novel implementation of DS-CDMA where chips are decomposable into N narrowband frequency components. With regard to the antenna array, we deploy the oscillating-beam smart array. Here, applying proper time-varying phases to the array elements, we create small movement (oscillation) in the antenna array's pattern, while steering the antenna pattern main lobe to the position of the intended user. The oscillating antenna pattern creates a time-varying channel with a controllable coherence time. This, in turn, provides transmit diversity in the form of a time diversity gain at the mobile receiver side. At the receiver, three stages of combining are available: combining time components of the received signal within symbol duration Ts (each experiencing a different fade) to enhance performance via time diversity; combining frequency components which make up the CI/DS-CDMA chip to enhance the performance via frequency diversity; and combining across chips to eliminate the interfering users on the system. Merging CI/DS-CDMA with the oscillating-beam smart antenna at the base station, we achieve very high capacity via the merger of SDMA (available through directionality of the antenna array) and code division multiple access (inherent in CI/DS-CDMA), and very high performance via the construction of receivers that exploit both transmit diversity and frequency diversity. We present the performance gains of the proposed merger.

The design of smart antenna system for handheld devices has been a challenge for years. In this study, an attempt is made to try to solve this challenge by applying an optimal design method for the antenna arrays introduced previously. The method is based on the optimisation of the power transmission efficiency between two antennas. During the optimisation, the smart antenna array to be designed is used as transmitting antenna, and a testing antenna is introduced as receiving antenna, positioned in the far-field region. The maximum (minimum) possible radiation may then be achieved in the direction of the testing antenna if the power transmission efficiency is maximised (minimised). A compact low-profile smart antenna system has been designed using the method, which works at GSM-900 and PCS-1900 band and employs four identical inverted-F antennas as radiating elements. The dimension of the whole system is 140 mm × 80 mm × 7 mm, suitable for the application in handheld devices or other customer-premises equipment.

In wireless communication systems, the antenna plays a crucial role because it is at the front end of the transceiver. Overall system performance depends on this. The performance of wireless communication is governed by the strength and quality of the signal and by efficiency. The size of wireless technology devices is shrinking rapidly. Antennas must be designed to be compact, small, and lightweight. The demand to incorporate multiple antennas in user devices containing numerous wireless applications is increasing. This chapter explores how multiband multiple-input multiple-output (MIMO) antenna solutions are helpful for the modern wireless communication system and why they are required. It focuses on designing and analyzing multiband MIMO antennas. The multiband MIMO antenna is described in a brief introduction. The chapter then investigates the isolation effect and how to improve MIMO antenna diversity performance for modern wireless applications. Enriched MIMO antenna structures are examined, including advanced MIMO antenna design techniques like characteristic mode analysis (CMA). The chapter is intended for researchers, professionals, and graduate students in electronics engineering, electromagnetics, communications, and signal processing, including antenna theory and design, smart antennas, and communication systems.

The innovative IEEE 802.11g based upon OFDM appears like a promising standard in the future. Interference, fading and coexistence issues, that can threaten it performance, are efficiently counteracted by smart antennas. This paper proposes a novel joint beamforming algorithm for a pair of communicating stations which does not need any extra bandwidth or resources than those provided by the standard. The suggested iterative approach is based on a specific optimization problem at each side of the link. The steady state solution yields to the minimization of the transmitted power for a desired SINK, that is an imperative optimization criterion when dealing with systems for which power consumption is crucial, such as laptops, hand-pc or mobile phones. Simulations show that the presented algorithm achieves rapid convergence towards the theoretical optimum solution.

Extending the mobile radio service to the newly developing regions is necessary for accelerating their economic and social progress. The cost and flexible deployment of such communication systems are the key issues. The emerging technology of stratospheric platform mobile communications is devised for covering such regions. Introducing smart antenna technology with this kind of communication systems provides additional improvements. The paper suggests several switched-beam smart antenna techniques in order to increase the user location accuracy especially in emergency situations, reduce power consumption, efficiently use the radio spectrum and reduce the errors resulting from the positional instability of the platform. In addition, the performance and feasibility of such approaches in terms of the hardware and processing requirements are addressed. The study dictates the adoption of beam-splitting approach as a superior one due to its compromise between the hardware and processing requirements.

The smart antenna technique as a method of improving the physical layer performance of OFDM WLANs is studied. For this purpose, a comparison of the smart antenna architectures for IEEE802.11a WLAN system using pre-FFT and post-FFT array processing with different parameters is represented. Simulations are performed on a new Simulink model for IEEE802.11a system using a spatio-temporal channel modeling which is based on the measured wideband channels in the 5GHz band. Raw bit-error-rate performance for QPSK/16QAM modulations at LOS and NLOS channel scenarios are evaluated and compared.

This chapter introduces a new security scheme for mobile anchors avoiding the physical layer attacks towards localization in wireless sensor networks (WSNs). In a network, anchors are made location-aware equipping them with GPS (global positioning system) receivers. Direction finding capabilities are also incorporated with smart antennas. The proposed algorithm is based on adaptive beamforming of smart array that always minimizes the probabilities of successful attacks, keeping the adversaries beyond its beam coverage. Particle swarm optimization (PSO) technique is used to compute array excitation coefficients, generating the desired pattern. Thus, anchors remain secured through pattern irregularities, deteriorating the information retrieval process even though chances of occurring adequate RSS (received signal strength)/AoA (angle of arrival) measurements may exist. Moreover, anchors are assumed to send pseudo references towards stationary nodes over private links, preserving data integrity for localization. Simulation results validate its effectiveness over the existing methods.

The wireless communication in 5G system enhances the transmission rate and the packet delivery ratio. There are several methods to improve the performance of 5G communication based on the optima selection of Antenna parameters. In this paper, a novel bilateral antenna pattern selection (BAPS) was proposed as the optimization technique for the best selection of spectrum pattern from the antenna parameters. Based on the Direction of Arrival (DOA), the best antenna was selected optimally to achieve the higher value of gain parameter. The spectrum of the signal was estimated to form the signal pattern of an antenna with the combination of beamforming technique to represent the design of smart antenna in the 5G communication system. These spectrum selections and the pattern validation of an DOA provides the best match of antenna that are selected for the communication. This improves the high gain and the signal strength for transmission. This also reduces the noise ratio in the signal. Due to the optimal selection of antenna parameters by using BAPS technique, this will reduce the power consumption than the traditional communication system. The result analysis validates the performance of proposed optimization technique by comparing with the other state-of-art methods.

Power consumption is a crucial design concern in mobile ad‐hoc networks (MANETs), since the nodes are powered by batteries with limited battery power, whereas the existing dynamic source routing (DSR) protocol does not take the battery power limitation of the MANET nodes into account. The mobile hosts in MANETs are constrained by the battery power for their operation. Hence, the battery power of a node is a precious resource that must be used efficiently in order to avoid early termination of a node or a network. In the MANET, power is one of the major issues, since the devices have limited battery power to execute the tasks. This study proposes a new scheme called efficient power routing DSR (EPRDSR) to improve the existing on‐demand routing protocols by introducing a power efficient scheme in the whole MANET. In the route discovery, the EPRDSR selects the bandwidth and the power constraints are built into the DSR route discovery mechanism. Hence, it enhances the network lifetime and delays the repair and reconstruction of the route. The main goal of EPRDSR is not only to extend the lifetime of each node, but also to prolong the lifetime of each connection.