Vol. 76, n° 11-12, November-December 2021
Content available on Springerlink
Joint transmit and receive beamforming for MIMO interference
channels using the difference of convex programming
Negin Danesh1 · Mansour Sheikhan1 · Behrad Mahboobi2
(1) Department of Electrical Engineering, Islamic Azad University, South Tehran Branch, Tehran, Iran
(2) Department of Electrical and Computer Engineering, Communication, Computer, and Industrial Network Research Center,
Islamic Azad University, Science and Research Branch, Tehran, Iran
Abstract Interference alignment (IA) techniques raise the achievable degree of freedom (DoF) in wireless interference networks by designing the aligned transceiver beamformers. The DoF shows the number of interference-free data streams that can be communicated simultaneously on a channel. To achieve the maximum possible DoF, we design the aligned beamformers in this study based on the interference leakage minimization (ILM) method for a multiple-input multiple-output interference channel (MIMO-IC). Accordingly, the ILM optimization problem is firstly relaxed to the rank constrained semidefinite programming (SDP) problems. Next, using a non-convex programming method (i.e., the difference of convex [DC] programming method), the proposed non-convex rank constrained SDP problem is reformulated to the DC form. We propose a novel DC-based IA algorithm that designs the optimized aligned beamformers based on an iterated local search using a penalty function. By increasing the penalty factor, the solution of the penalized DC problem converges to the solution of the original DC problem. Unlike the previous IA approaches, the proposed DC-based IA algorithm optimizes transmit and receive beamformers jointly and simultaneously in each iteration (i.e., not alternately). Simulation results indicate that the proposed method outperforms the previous competitive IA algorithms by providing more throughputs and less interference leakage as compared to the least-squares (LS)-based and the minimum mean square error (MMSE)–based IA algorithms.
Keywords Beamforming . MIMOinterference channels . Convex programming
Audio quality level vs. signal-to-interference ratio in isofrequency
Marco De Piante1 · Stefano Boscolo1 · Emanuele Turco1 · Paolo Gardonio1 · Michele Midrio1
(1) Dipartimento Politecnico di Ingegneria e Architettura, Università degli Studi di Udine, via delle Scienze 206, Udine, Italy
Abstract Frequency modulated (FM) transmissions play a key role into radio broadcasting. This paper presents a study on the audio quality of demodulated FM transmissions corrupted by co-channel interference. A panel of listeners has judged audio signals containing the superposition of “desired” and “interfering” signals with different signal-to-interference ratios (SIR). The paper summarises the outcomes of a comprehensive campaign of audio tests, which provide detailed estimates of the perceived quality of interfered FM transmissions. Furthermore, the paper presents a thorough analysis and interpretation of the tests, which establishes a relationship between five-grade ITU-R BS.1284-2 QoS scale and signal-to-interference ratio (SIR).
Keywords Analogic radio broadcast · Audio quality · FM performances · Frequency modulation
Double spatial media-based modulation with RF mirrors
Ronald Tsvaki1 · Narushan Pillay1 · Hongjun Xu1
(1) University of KwaZulu-Natal, School of Engineering, Durban, Republic of South Africa
Abstract Media-based modulation (MBM) is an attractive transmission technique that has been recently receiving increased research attention in the wireless communication domain. MBM employs the use of radio frequency mirrors to vastly improve the error performance and/or spectral efficiency of transmission schemes as compared to traditional source-based modulation techniques. Double spatial modulation (DSM) is a new multiple-input multiple-output transmission technique that aims to improve the spectral efficiency of conventional spatial modulation by increasing the number of active transmit antennas. In this study, DSM is extended to employ MBM, such as to improve error performance, and the scheme is termed double spatial media-based modulation (DSMBM). The theoretical average bit error probability of DSMBM is formulated and validated by Monte-Carlo simulation results. Lastly, coded channels are investigated. Typically, soft-output detection coupled with soft-input channel decoding yields a significant signal-to-noise ratio gain. Hence, the authors further propose soft-output maximum-likelihood detectors for the DSM and DSMBM systems.
Keywords Double spatial modulation (DSM) · Media-based modulation (MBM) · Multiple-input multiple-output ·
Radio frequency mirrors · Soft-output maximum-likelihood detector · Spatial modulation
A non-stationary relay-based 3D MIMO channel model
with time-variant path gains for human activity recognition
in indoor environments
Rym Hicheri1 · Ahmed Abdelgawwad1 · Mathias Pätzold1
(1) Faculty of Engineering and Science, University of Agder, Grimstad, Norway
Abstract Extensive research showed that the physiological response of human tissue to exposure to low-frequency electromagnetic fields is the induction of an electric current in the body segments. As a result, each segment of the human body behaves as a relay, which retransmits the radio-frequency (RF) signal. To investigate the impact of this phenomenon on the Doppler characteristics of the received RF signal, we introduce a new three-dimensional (3D) non-stationary channel model to describe the propagation phenomenon taking place in an indoor environment. Here, the indoor space is equipped with a multiple-input multiple-output (MIMO) system. A single person is moving in the indoor space and is modelled by a cluster of synchronized moving point scatterers, which behave as relays. We derive the time-variant (TV) channel transfer function (CTF) with TV path gains and TV path delays. The expression of the TV path gains is obtained from the instantaneous total received power at the receiver side. This TV total received power is expressed as the product of the TV power of the RF signal initially transmitted and received by a body segment and the TV received power of the redirected signal. These TV powers are determined according the free-space path-loss model. Also, a closed-form approximate solution to the spectrogram of the TVCTF is derived. Here, we analyse the effect of the motion of the person and the validity of the relay assumption on the spectrogram, the TV mean Doppler shift (MDS), and the TV Doppler shift (DS) of the TVCTF. Simulation results are presented to illustrate the proposed channel model.
Keywords Non-stationary channels · Doppler characteristics · Time-variant path gains · Spectrogram ·
Multiple-input multiple-output systems · Human activities recognition
Modeling and improving named data networking over IEEE 802.15.4
Amar Abane1 · Paul Muhlethaler1 · Samia Bouzefrane2
(1) Inria, Paris, France
(2) CNAM, Paris, France
Abstract Named Data Networking (NDN) is a promising architecture that aims to natively satisfy emerging applications such as the Internet of Things (IoT). Therefore, enabling NDN in real-world IoT deployments is becoming essential in order to benefit from Information Centric Networking (ICN) features. To design realistic NDN-based communication solutions for IoT, revisiting mainstream technologies such as low-power wireless standards may be the key. In this paper, we explore NDN forwarding over IEEE 802.15.4 following two steps. First, we mathematically model a broadcast-based forwarding strategy for NDN over constrained networks with the IEEE 802.15.4 technology in mind. The model estimates the number of frames transmitted and the mean round-trip time per request, under content popularity considerations. Second, based on mathematical and experimental observations of the broadcast-based forwarding at network level, we elaborate Named-Data Carrier-Sense Multiple Access (ND-CSMA), an adaptation of the Carrier-Sense Multiple Access (CSMA) algorithm used in IEEE 802.15.4. Results show that adaptations such as ND-CSMA may be reasonably envisioned to improve NDN efficiency with current IoT technologies.
Keywords NDN · ICN · IoT · IEEE 802.15.4 · Mathematical model · CSMA · Low-power wireless