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Interference Impact of Wireless Avionics Intra-Communication Systems onto Aeronautical Radio Altimeters

In this paper an assessment concerning the potential impact of interference caused by transmissions of wireless avionics intra-communication systems onto aeronautical radio altimeter operating co-frequency is presented. The radio altimeter model utilized for the assessment accounts for realistic scattering and antenna characteristics to describe echo signals returned by the Earth surface. It includes a detailed description of the signal processing and detection stages allowing for a comprehensive analysis of the interference impact.

The interference of wireless avionics intra-communication transmissions is modeled by offset quadrature phase-shift keying modulated signals which are added to radio altimeter receive antenna output signal. The assessment covers a broad range of potential interference scenarios. It includes a detailed analysis of the spectral characteristics of wireless avionics intra-communication signals observed in the radio altimeter detection stage and an evaluation of their impact onto the altitude detection reliability.

Front-end Monitoring of Multiple Loads in Wireless Power Transfer Systems Without Wireless Communication Systems

This paper describes a method for monitoring multiple loads from the front-end of a wireless power transfer system without using any wireless communication systems. A mathematical approach based on scanning the frequency around the resonant frequency has been developed for deriving the load conditions.

The proposal requires only information of the input voltage and current only, therefore eliminating the requirements of using wireless communication systems for feedback control. The proposal has been practically confirmed in hardware prototype with acceptable results.

Admission Control Scheme for Service Dropping Performance Improvement in High-Speed Railway Communication Systems

In high-speed railway communication (HSRC) systems, ensuring the continuity of on-going services is one of the toughest challenges, for the existence of influential factors such as frequent handoff event, short time window for handoff, and severe channel distortion, etc. In HSRC systems with limited resources, admission control (AC) is one of the most efficient methods to overcome this challenge and guarantee the requirement of service dropping probability (SDP). However, now it still lacks of recognized AC scheme that can be used in HSRC systems. In this paper, a novel AC scheme is proposed to HSRC systems, where resource reservation algorithm and resource preemption model are developed together to reduce the SDP.

First, the main reasons of on-going service dropping related to AC scheme are analyzed, which include frequent adjustment of services’ modulation-and-coding-scheme (MCS) and continual handoff events. Second, an adaptive resource reservation algorithm is proposed to optimize the amount of reserved bandwidth for ongoing services, where the effect of MCS change at physical-layer and the characteristics of HSRC are both taken into account. Third, considering the effect of resource preemption on on-going services, a resource preemption model is developed to further obtain the available bandwidth resources. Then, according to the above works, the AC scheme is proposed to optimize the SDP performance. Finally, simulation results are presented to demonstrate the effectiveness of the proposed AC scheme.

Summary of results in the field of small element antenna arrays for mobile communication systems

Development of the theory and technology of the small element antenna arrays is one of the research areas of the Department of Technical Electromagnetics and Radio communication Systems since 2006. The research is focused on the improvement of the mobile communication systems.

Curvilinear antenna arrays are proposed that comprise antenna elements with controllable polarization of radiation, which are located along the ellipse arc. The potential emitting properties of such antenna arrays have been estimated. The adaptive beamforming algorithm with the necessary directional characteristics and controllable polarization of radiation is presented.

Spectrum sharing between matrix completion based MIMO radars and a MIMO communication system

Recently proposed multiple input multiple output radars based on matrix completion (MIMO-MC) employ sparse sampling to reduce the amount of data forwarded to the radar fusion center, and as such enable savings in communication power and bandwidth. This paper proposes designs that optimize the sharing of spectrum between MIMO-MC radars and MIMO communication systems, so that the latter interferes minimally with the former.

First, the communication system transmit covariance matrix is designed to minimize the effective interference power (EIP) at the radar receiver, while maintaining certain average capacity and transmit power for the communication system. Two approaches are proposed, namely a noncooperative and a cooperative approach, with the latter being applicable when the radar sampling scheme is known at the communication system. Second, a joint design of the communication transmit covariance matrix and the MIMO-MC radar sampling scheme is proposed, which achieves even further EIP reduction.

Terahertz resonant tunneling diode systems for next generation wireless communication

For low cost and short distance wireless data communication systems in the THz frequency range, resonant tunneling diodes (RTDs) are very promising. To obtain a large signal-to-noise ratio, thus high data rate, the transmitter output power and receiver sensitivity have to be high.

In this paper, we discuss how to overcome the limitations of current RTD-based systems for wireless communication with respect to circuit design, showing our latest experimental results.

High rate communications systems for CubeSats

Small Satellites and especially CubeSat have received significant attention recently. The development of secondary launch systems to provide a reasonably priced ride to space has increased the number of small satellites in orbit. Recent subsystem developments have also supported this revolution. One area that has been slow to develop is high rate communications. Early CubeSat systems were built on the amateur satellite service, but the available data rates are low.

Efforts are evolving to develop high rate CubeSat transceivers. This paper will provide an overview of current CubeSat communication systemscapabilities in addition to details about an effort to develop a high rate CubeSat communication system that is compatible with the NASA Near Earth Network. The system includes a 200kbps S-Band receiver and a 12.5Mbps X-Band transmitter.

Novel timing synchronization technique for public safety communication systems employing heterogeneous cognitive radio

A novel synchronization technique is proposed for a heterogeneous cognitive radio combining a public safety mobile communication system (PMCS) with a commercial mobile wireless communicationsystem (CMWCS). Since the PMCS is crucial in public safety activities such as search-and-rescue operations, we have implemented a heterogeneous cognitive technique to improve the communicationquality of the PMCS. To combine the PMCS with the CMWCS properly, the proposed synchronization technique enables not only the co-synchronization between the PMCS and the CMWCS but also the self-synchronization of the PMCS.

In this paper, we especially focus on the PMCS’s self-synchronization that is one of the most difficult parts of our proposed cognitive radio system. The proposed technique is utilized for systems employing differentially encoded 7t/4-shift QPSK modulation. The synchronization can be achieved by correlating the envelopes calculated from the PMCS’s received signals with subsidiary information (SI) sent via the CMWCS. In this study, the performance of the proposed synchronization technique is evaluated by computer simulation.

Atmospheric Attenuation in Wireless Communication Systems at Millimeter and THz Frequencies [Wireless Corner]

This paper intends to give an overview about atmospheric propagation effects affecting millimeter and terahertz (THz) communication systems. The main focus is on attenuation caused by atmospheric gases and liquid water droplets, either in the form of suspended particles into clouds or rain falling hydrometeors.

Theoretical aspects about each of them are presented, emphasizing on those that deserve special attention as frequency increases. Statistics of attenuation estimated from meteorological data and some experimental results, as in the case of rain attenuation, obtained in Madrid, Spain, are presented throughout the paper, thus providing further insights about the phenomena discussed.

A comprehensive survey of TDD-based mobile communication systems from TD-SCDMA 3G to TD-LTE(A) 4G and 5G directions

TDD (Time Division Duplex) is one of the two duplex modes. TD-SCDMA (Time Division Synchronous CDMA) is the first TDD-based cellular mobile system which is commercialized in wide area and large scale and TD-SCDMA is also the first cellular mobile system which adopted smart antenna technology (also called as beamforming). As the long term evolution of TD-SCDMA, TD-LTE(A) (Time Division-Long Term Evolution, and TD-LTE Advanced) introduced OFDM (Orthogonal Frequency Division Multiplexing) and enhanced smart antenna technology together with MIMO (Multiple Input Multiple Output), which are adopted by LTE FDD (Frequency Division Duplex) either. It is indicated that TD-SCDMA and TD-LTE(A) have opened a sustainable utilization era of TDD and smart antenna technologies in the wireless mobile communication.

This paper aims to present a systematic introduction to TDD-based mobile communications from TD-SCDMA to TD-LTE and beyond, with particular focuses on TDD key technologies, principles of TDD cellular mobile systems, TDD evolution path, and future TDD 5G directions. The comparisons between TDD and FDD are also included. We hope that this paper will provide a comprehensive overview of TDD technology upgrade and its standard evolution, and serve as a valuable reference for research on 5G mobile communicationsystems. It is believed that TDD will play more important role in 5G.