An adaptive nulling antenna system for space based radar with array element reuse

Performances of an adaptive array antenna system for land mobile communications have been investigated through computer simulation and experiments. The adaptive array antenna system can automatically form nulls in the direction of undesired wave on receiving directional pattern. First, it is verified by computer simulation that only desired wave is received without interference by the system controlled on the basis of CMA, when the desired and undesired waves arrive at the receiving point together. Next, it is experimentally indicated that the undesired wave is suppressible by approximately 20 dB, even if the antenna element of the system has not an omni-directional pattern. From these studies, it is confirmed that the adaptive array antenna system is very useful for high quality land mobile communications.

Multipath fading and human body influence affect the performance of a Low Earth Orbit Satellite (LEOS) handheld terminal. In this research, the effectiveness of optimum combining is compared with selection diversity and omni-directional antenna systems. By using the electric field and magnetic field antennas, zero correlation can be provided. In the presence of interference, adaptive antennas can nullify the interference. In the absence of interference, adaptive antennas can maximise the final Signal to Noise Ratio (SNR). In this case, an adaptive antenna is the same as a maximum ratio combiner. An adaptive antenna system provides a 2.0dB gain on average when its performance is compared with the selection diversity system. The adaptive antenna system also provides a 9.5dB gain on average when its performance is compared with the omni-directional antenna system. Finally, adaptive antennas can automatically resolve the phase ambiguity effect, so that differential coding is not required. Therefore, an extra 3dB gain can be obtained.

We study the antenna gain of an adaptive smart antenna system. The motivation for using the smart antenna systems is to increase the antenna gain and to extend the coverage of the system. Unlike traditional antennas whose gain is fixed, the gain of smart antenna systems depends on the signal processing algorithms used, the signal-to-noise ratio, and the data symbol size. We evaluate the antenna gain associated with several typical algorithms including an efficient one introduced in the paper. The effect of the signal-to-noise ratio and sample size on the antenna gain is also analyzed via statistical analysis as well as by computer simulations. Numerical results show that the adaptive smart antenna system can obtain close to the theoretical limit, i.e., 10 log/sub 10/ M[dB], where M is the number of antennas in a typical wireless communication environment.

A broadband adaptive array antenna system was built in lab to check the signal processing algorithm. The antenna element, the RF receiving module and the digital processing unit are presented step by step. Especially for the signal processing, both the hardware platform and the software algorithm are researched together. In multiuser circumstances, a decorrelating detector is usually adopted to detect multiuser, here a novel CSS algorithm is presented according to CDMA communications system requests.

This contribution presents some simulation results obtained by a WCDMA base station equipped with an adaptive antenna system. The results show that the performance gain obtained by an advanced antenna system could be substantial compared to an ordinary sector covering system. Migrating some existing sites/sectors to adaptive antenna systems can be seen as one attractive solution that increases capacity in a coverage area without condensing the system by building additional cell sites. To find out where this grow-on-site migration strategy is most beneficiary, it is important to evaluate the systems by taking typical user scenarios into account. The user scenarios includes spatially distribution of users as well as the expected user behavior related to the actual application (or user data rate). It has been shown that the gains using adaptive antennas for the investigated scenarios of non-uniformly distributed mixed service users are substantial.

Adaptive antenna technique has an important role in the IoT environment in order to establish reliable and stable wireless communication in high congestion situation. Even if knowing antenna characteristics in advance, electromagnetic wave propagation in non-line-of-sight environment is very complex and unpredictable, therefore, the adjustment the antenna radiation for the optimum signal reception is important for the better wireless link. This article presents a simple but effective adaptive antenna system for Wi-Fi utilizing the function of a highly integrated component, ESP32-PICO-D4. This chip is a system-in-chip containing all components for Wi-Fi and Bluetooth application except for antenna. Together with SP3T RF switch and dielectric antennas and high-resolution audio DAC, completed web-radio system is made in the size of 50 × 50 mm. Keywords: Beam switching, Adaptive antenna, System-in-chip, ESP32, Web-radio

The speed of progress in wireless communication requires smart, adaptive antenna systems that can enhance network performance in dynamic environments. This chapter presents AI-based adaptive antenna systems for smart communication networks. By using machine learning algorithms, the antenna adjusts beamforming and polarization in real-time to optimize signal quality, decrease interference, and increase throughput. We describe the architecture, the algorithmic framework, and the experimental validation. The results show a remarkable improvement in spectral efficiency and network reliability, highlighting the superiority of AI in future adaptive antenna technology.

Adaptive smart antenna system manipulates the signal impinging on various antenna elements in such a way that, the main beam is directed towards the desired signal and a null is formed in the direction of interferers. Such smart antenna systems play a very important role in wireless and military applications as they can increase capacity, coverage range and resolution. To locate the desired signal, in smart antenna system direction of arrival (DOA) estimation algorithms MUSIC and ESPRIT are considered. This paper evaluates and compares MUSIC and ESPRIT DOA estimation algorithms which are mostly used in design of adaptive antenna system. MUSIC and ESPRIT provide a higher resolution and accuracy hence, are explored much in detail. Implementation of MUSIC and ESPRIT shows that, MUSIC is more stable and accurate than ESPRIT therefore, MUSIC is widely used to detect DOA of incoming signals.

This paper proposes a mathematical framework for evaluating, in saturated and non-saturated traffic conditions, the performance of an 802.11 wireless network in which the nodes are equipped with adaptive antenna systems. The analysis, validated by simulations, adopts detailed models for the antenna behavior and the propagation environment, taking into account multipath and interference. The developed model is used to investigate the proper parameter settings that lead to throughput maximization, providing a simplified method to obtain the optimum contention window when adaptive arrays are employed.

In a multihop ad hoc network, end-to-end data transmissions traverse through multiple inter-node wireless links. A jammer can disrupt the entire data transfer of a network by intentionally interfering with links between a subset of nodes. The impact of such attacks is escalated when the jammer is moving. While the majority of current ad hoc protocols consider omnidirectional transmission and reception, adaptive antennas can be utilized for spatial filtering of the jamming signal. This paper investigates the performance of employing adaptive beam nulling as a mitigation technique against jamming attacks in multihop ad hoc networks. Considering a moving jammer, the survivability of links and connectivity in such networks are studied by simulating various node distributions and different mobility patterns of the attacker. In addition, the impact of errors in estimation of direction of arrival and beamforming on the overall network performance are also examined. The results indicate a significant improvement in retaining connectivity under jamming when adaptive beam nulling is applied.

The ever growing demand for mobile communications is pushing the technology towards its very limits. In addition, the current technology is optimized for circuit-switched voice rather than bandwidth hungry services such as wireless Internet and multimedia applications. The third generation mobile systems that will be introduced in the near future are designed specifically to address these limitations. In this paper, we focus on EGPRS, the evolutionary path for the GSM and the TDMA IS-136 systems to provide third generation packet-switched services. We outline a simulation methodology which can be used to evaluate the system level performance of EGPRS for an adaptive antenna system. We then show, via simulations, that the use of the adaptive antenna system can significantly enhance the quality of service and the network capacity of EGPRS. For example, a capacity gain of over 200% can be achieved for the 1/3 frequency reuse scheme.

In the realization of code-division multiple access based on a spread-spectrum communication system, i.e. spread-spectrum multiple access (SSMA), reduction of cochannel interference is an important problem. An adaptive array antenna system is proposed that includes a cancellor of cochannel interference, which can improve performance by a combination of temporal and spatial filtering. While the adaptive array suppresses interference sources with arrival angles different from those of the desired user, the adaptive digital filter-canceller rejects those whose arrival angles are the same as those of the desired user. The proposed system can achieve stable acquisition and low error rate of demodulated data even in a heavy-interference channel where a conventional array antenna system cannot achieve satisfactory acquisition.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Smart Antenna Systems (SAS) are largely employed in wireless networks for their capabilities to provide very high performances with respect to omnidirectional antennas. The use of adaptive array Smart Antenna could bring to enhance aspects such as energy management, especially in Mobile Ad Hoc Network (MANET), when the network performance closely depends on the battery life of the mobile nodes as well as on the routing protocol features. In this paper, we propose a new adaptive array Smart Antenna System that improves some Ad Hoc Distance Vector (AODV) network protocol features through a mechanism of energy consumption optimization. The system implements the Least Mean Square (LMS) as adaptive algorithm; for this purpose, we perform a co-simulation between Matlab, that implements the LMS algorithm and Omnet++, that provides a complete simulation environment for MANET.

Currently, a growing number of satellite communication systems developers and manufacturers pay attention to the adaptive multibeam antenna systems. These systems allow you to implement flexible traffic management by forming a multi-beam patterns within the service area. In addition, they have such an important property, as the high noise immunity when exposed as a deliberate and industrial noise provided by the use of spatial filtering methods for interference. The adaptive multibeam antenna can be built on the basis of a phased antenna arrays with scanning beams and multibeam antennas are constructed on the basis of hybrid reflector antennas [1]. The main control element of such antennas is a block adaptation that implements control algorithms and individual beams beamforming. A block adaptation is a processor based on the adaptive signal processor, and the adaptation is made on the program level. In [2] made

A new type of adaptive beamforming antenna system architecture is proposed for multichannel wireless communications. Multibeam communication with high data throughput is accomplished using the proposed beamformer architecture. The system consists of analog mixers, a multitone direct digital synthesizer (DDS), and a digital signal processor (DSP) controller. The essential idea of multibeam forming is based on a multitone weighting scheme combined with analog-digital hybrid signal processing. While the real-time multibeam construction is realized by the analog mixer circuits and a DDS, the complicated adaptive beamforming and direction-of-arrival estimation algorithms are carried out by the DSP. In this architecture, only one beamformer circuit is required to handle multiple beams, leading to significant reduction in hardware counts. A 5.8-GHz eight-element adaptive beamforming array successfully demonstrates two-beam simultaneous beamforming with less than three degrees of peak and null steering errors and more than 20-dB interference suppression. The test-bed exhibits successful two-channel data recovery at 25-Mb/s data throughput in each channel with binary phase-shift keying modulation, for simultaneous dual-beam reception. The bit-error-rate measurement validates the robustness of the communication quality under strong interferences.