Laboratory measurement campaign of DVB-T signal with transmit delay diversity

The requirements for future DVB-T/H networks demand that broadcasters design and deploy networks that provide ubiquitous reception in challenging indoors and other obstructed situations. It is essential that such networks are designed cost-effectively and with minimized environmental impact. The EC funded project PLUTO has since its start in 2006 explored the use of diversity to improve coverage in these difficult situations. The purpose of this paper is to investigate the performance of Transmit Delay Diversity (DD) with two antennas to improve the reception of DVB-T/H systems operating in different realistic propagation conditions through a series of tests using a SPIRENT SR5500 dual channel emulator. The relationship between correlation coefficient between channels, receiver velocity and diversity gain is nvestigated. It is shown that transmit delay diversity significantly improves the quality of reception particularly in simulated fast fading mobile broadcasting applications. This paper documents research conducted by Brunel University and Broadreach Systems

5G New Radio Evolution Towards Sub-THz Communications

In this paper, the potential of extending 5G New Radio physical layer solutions to support communications in sub-THz frequencies is studied. More specifically, we introduce the status of third generation partnership project studies related to operation on frequencies beyond 52.6 GHz and note also the recent proposal on spectrum horizons provided by federal communications commission (FCC) related to experimental licenses on 95 GHz - 3 THz frequency band. Then, we review the power amplifier (PA) efficiency and output power challenge together with the increased phase noise (PN) distortion effect in terms of the supported waveforms. As a practical example on the waveform and numerology design from the perspective of the PN robustness, link performance results using 90 GHz carrier frequency are provided. The numerical results demonstrate that new, higher subcarrier spacings are required to support high throughput, which requires larger changes in the physical layer design. It is also observed that new phase-tracking reference signal designs are required to make the system robust against PN. The results illustrate that single-carrier frequency division multiple access is significantly more robust against PN and can provide clearly larger PA output power than cyclic-prefix orthogonal frequency division multiplexing, and is therefore a highly potential waveform for sub-THz communications.Comment: This manuscript has been accepted for publication to IEEE 6G Wireless Summit 2020, 6 pages, 4 figure

Experimental evaluation of interference alignment for broadband WLAN systems

In this paper, we present an experimental study on the performance of spatial interference alignment (IA) in indoor wireless local area network scenarios that use orthogonal frequency division multiplexing (OFDM) according to the physical-layer specifications of the IEEE 802.11a standard. Experiments have been carried out using a wireless network testbed capable of implementing a 3-user MIMO interference channel. We have implemented IA decoding schemes that can be designed according to distinct criteria (e.g., zero-forcing or MaxSINR). The measurement methodology has been validated considering practical issues like the number of OFDM training symbols used for channel estimation or feedback time. In case of asynchronous users, a time-domain IA decoding filter is also compared to its frequency domain counterpart. We also evaluated the performance of IA from bit error ratio measurement-based results in comparison to different time-division multiple access transmission schemes. The comparison includes single- and multiple-antenna systems transmitting over the dominant mode of the MIMO channel. Our results indicate that spatial IA is suitable for practical indoor scenarios in which wireless channels often exhibit relatively large coherence times.This work has been supported by Xunta de Galicia, MINECO of Spain, and by FEDER funds of the E.U. under Grant 2012/287, Grant TEC2013-47141-C4-R (RACHEL project), Grant CSD2008-00010 (COMONSENS project), and FPU Grants AP2010-2189 and AP2009-1105

An Analysis of Electromagnetic Interference (EMI) of Ultra Wideband(UWB) and IEEE 802.11A Wireless Local Area Network (WLAN) Employing Orthogonal Frequency Division Multiplexing (OFDM)

Military communications require the rapid deployment of mobile, high-bandwidth systems. These systems must provide anytime, anywhere capabilities with minimal interference to existing military, private, and commercial communications. Ultra Wideband (UWB) technology is being advanced as the next generation radio technology and has the potential to revolutionize indoor wireless communications. The ability of UWB to mitigate multipath fading, provide high-throughput data rates (e.g., greater than 100 Mbps), provide excellent signal penetration (e.g., through walls), and low implementation costs makes it an ideal technology for a wide range of private and public sector applications. Preliminary UWB studies conducted by The Institute for Telecommunications Science (ITS) and the Defense Advanced Research Projects Agency (DARPA) have discovered that potential exists for harmful interference to occur. While these studies have provided initial performance estimates, the interference effects of UWB transmissions on coexisting spectral users are largely unknown. This research characterizes the electromagnetic interference (EMI) effects of UWB on the throughput performance of an IEEE 802.11a ad-hoc network. Radiated measurements in an anechoic chamber investigate interference performance using three modulation schemes (BPSK, BPPM, and OOK) and four pulse repetition frequencies over two Unlicensed National Information Infrastructure (U-NII) channels. Results indicate that OOK and BPPM can degrade throughput performance by up to 20% at lower pulse repetition frequencies (PRFs) in lower U-NII channels. Minimal performance degradation (less than one percent) due to interference was observed for BPSK at the lower PRFs and higher U-NII channels

A MIMO-OFDM testbed, channel measurements, and system considerations for outdoor-indoor WiMAX

The design, implementation, and test of a real-time flexible 2×2 (Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing) MIMO-OFDM IEEE 802.16 prototype are presented. For the design, a channel measurement campaign on the 3.5GHz band has been carried out, focusing on outdoor-indoor scenarios. The analysis of measured channels showed that higher capacity can be achieved in case of obstructed scenarios and that (Channel Distribution Information at the Transmitter) CDIT capacity is close to (Channel State Information at the Transmitter) CSIT with much lower complexity and requirements in terms of channel estimation and feedback. The baseband prototype used an (Field Programmable Gate Array) FPGA where enhanced signal processing algorithms are implemented in order to improve system performance. We have shown that for MIMO-OFDM systems, extra signal processing such as enhanced joint channel and frequency offset estimation is needed to obtain a good performance and approach in practice the theoretical capacity improvements

Regulatory and Policy Implications of Emerging Technologies to Spectrum Management

This paper provides an overview of the policy implications of technological developments, and how these technologies can accommodate an increased level of market competition. It is based on the work carried out in the SPORT VIEWS (Spectrum Policies and Radio Technologies Viable In Emerging Wireless Societies) research project for the European Commission (FP6)spectrum, new radio technologies, UWB, SDR, cognitive radio, Telecommunications, regulation, Networks, Interconnection