UAV Command and Control, Navigation and Surveillance: A Review of Potential 5G and Satellite Systems

Drones, unmanned aerial vehicles (UAVs), or unmanned aerial systems (UAS) are expected to be an important component of 5G/beyond 5G (B5G) communications. This includes their use within cellular architectures (5G UAVs), in which they can facilitate both wireless broadcast and point-to-point transmissions, usually using small UAS (sUAS). Allowing UAS to operate within airspace along with commercial, cargo, and other piloted aircraft will likely require dedicated and protected aviation spectrum at least in the near term, while regulatory authorities adapt to their use. The command and control (C2), or control and non-payload communications (CNPC) link provides safety critical information for the control of the UAV both in terrestrial-based line of sight (LOS) conditions and in satellite communication links for so-called beyond LOS (BLOS) conditions. In this paper, we provide an overview of these CNPC links as they may be used in 5G and satellite systems by describing basic concepts and challenges. We review new entrant technologies that might be used for UAV C2 as well as for payload communication, such as millimeter wave (mmWave) systems, and also review navigation and surveillance challenges. A brief discussion of UAV-to-UAV communication and hardware issues are also provided.Comment: 10 pages, 5 figures, IEEE aerospace conferenc

Common Mode Characterization and Channel Model Verification for Shielded Twisted Pair (STP) Cable

This paper investigates common-mode propagation in shielded twisted pair cables. The common mode exhibits great potential for improving the throughput in emerging wireline systems. The design of corresponding transmission schemes over multipair copper cables requires accurate knowledge of the channel properties. We present measurement and modeling results and investigate the feasibility of using standard differentialmode models for data fitting in multiconductor transmission-line modelling of common-mode paths

Common-Mode Aided Wireline Communications

Wireline communication is the Internet access technology with the largest number of subscribers worldwide. On physical-layer level, the traditional way to transmit signals at one end of a wire pair and to extract receive signals at the other end is to apply differential-mode signalling: transmit and receive signals correspond to voltage differences between the two wires. Differential-mode signalling over twisted-wire pairs, proposed and patented more than hundred years ago, yields a communication channel with good and stable transmission characteristics and high immunity to noise and interference. The differential mode is the only propagation mode in a two-conductor system. Taking into account earth as a third conductor yields a second independent mode, the so-called common mode, which can be used for communication. This thesis deals with information processing methods to exploit both modes jointly in order to improve transmission. The material can be divided into three parts. The first part investigates basic characteristics of the common mode and the resulting channel when taking into account the common-mode signal at the receiver. Measurements of common-mode signals and common-mode cable properties are presented and analysed. The design of receivers that use the common-mode signal for mitigation of both narrowband disturbers and broadband interference is addressed. The second part focuses on the potential gain in throughput that can be achieved with common-mode aided transmission techniques. The Shannon capacity of the common-mode aided wireline channel is derived and evaluated, and the performance under specific constraints of existing digital subscriber line techniques is addressed. A rough prospect of the Swedish copper access network used with common-mode aided methods and other advanced techniques is presented. The third part of the thesis deals with techniques to reduce unwanted spectral egress, which is a prerequisite for employing the common mode as active mode for transmission. The investigations focus on discrete Fourier-transform based multicarrier systems with a Gaussian channel known to transmitter and receiver. Information processing techniques that maximise the throughput under arbitrary power spectral density constraints are devised. In particular, transmit-windowing techniques and the so-called spectral-compensation method are investigated

Spectral Compensation for Multicarrier Communication

Spectral compensation is an information-processing technique applied in the transmitter to improve the spectral efficiency of multicarrier modulation under a given power spectral density constraint. A set of carefully chosen tones, the so-called information tones, carries data. The. remaining tones, referred to as compensation tones, are modulated with a linear combination of the data, such that the spectral characteristic of the transmit signal and thus the throughput are improved. This paper investigates strategies to find the set of compensation tones and presents the optimal solution for the linear combination of the data given the tone-set split. The optimality criterion is maximization of throughput for a time-dispersive Gaussian channel known to the transmitter. Furthermore, a. suboptimal design is proposed, which has low runtime-complexity and achieves near-optimal performance

Optimal Intra-Symbol Transmit Windowing for Multicarrier Modulation

Abstract — Windowing of the transmitted blocks in a multicarrier system yields an improved spectral containment of the resulting basis functions, which allows larger transmit power compared to no windowing while fulfilling the power spectral density (PSD) requirements. Most transmit window designs proposed so far aim at maximising the mainlobe energy and thus the spectral containment of the transmit basis functions. In this paper, we compute the transmit window that is optimal in the sense of maximising the information rate for a time-dispersive Gaussian channel known to the transmitter and compare it to the maximum mainlobe-energy window. It is shown that the maximum-rate window outperforms the maximum mainlobe-energy window in terms of information rate, particularly for low SNRs and for short cyclic extensions. The out-of-band PSD characteristics of the maximum mainlobeenergy window is superior for short cyclic extensions but gradually deteriorates with the length of the cyclic extension. I

Optimal intra-symbol transmit windowing for multicarrier modulation

Windowing of the transmitted blocks in a multicarrier system yields an improved spectral containment of the resulting basis functions, which allows larger transmit power compared to no windowing while fulfilling the power spectral density (PSD) requirements. Most transmit window designs proposed so far aim at maximising the mainlobe energy and thus the spectral containment of the transmit basis functions. In this paper, we compute the transmit window that is optimal in the sense of maximising the information rate for a time-dispersive Gaussian channel known to the transmitter and compare it to the maximum mainlobe-energy window. It is shown that the maximum-rate window outperforms the maximum mainlobe-energy window in terms of information rate, particularly for low SNRs and for short cyclic extensions. The out-of-band PSD characteristics of the maximum mainlobeenergy window is superior for short cyclic extensions but gradually deteriorates with the length of the cyclic extension

Benchmarking of learning architectures for digital predistortion

Indirect and direct learning architectures are the two main parameter identification approaches for digital predistortion systems. While the indirect scheme is less complex, its inherent shortcomings are avoided by the direct learning approach. Trying to answer the question whether this advantage of the direct approach can be exploited in terms of measurable linearization-performance improvement in a predistortion platform for advanced power amplifier structures, we present a performance comparison based on laboratory results for wideband high-power Doherty amplifiers. Rather than using single-shot least-squares estimates, each architecture is combined with an adaptive parameter-update scheme to reach the desired performance range and allow for a fair comparison. In conclusion, although the direct learning approach may excel in peak performance, the indirect learning approach achieves virtually the same average performance over linearization runs and has a clear advantage in terms of robustness

Longitudinal Signals in DSL

The purpose of this contribution is twofold. First, we revisit the longitudinal component (also referred to as common-mode component, asymmetric component or antenna-mode component) occurring at the receive side of a twisted-pair loop. Second, we propose a simple setup for RFI tests that captures reality more accurately than performing differential-mode and common-mode tests separately. In essence, we agree with and support the test environments proposed in [1][2][3]. We stress the fact that differential-mode and common-mode signals should be generated jointly in order to account for their correlation