Frequency-hopping trellis-coded 8-DPSK for indoor communications

A TDMA (time-division multiple-access) slow frequency hopping-trellis-coded 8-DPSK (differential phase-shift keying) scheme is proposed for indoor mobile radio communications. In order to assess the performance of this scheme, a GWSSUS (Gaussian wide-sense stationary uncorrelated scattering) continuous channel model with an exponential power delay profile has been adopted. This channel model allows one to analyze transmission rates much lower than the inverse of the RMS (root mean square) delay spread. Bit error rate (BER) is obtained, through Monte Carlo computer simulation, as a function of signal-to-noise ratio and with normalized frequency-hopping separation and number of hopping-frequency channels as parameters. It is found that the degradation of the system BER performance with respect to the null-correlation case is, for normalized frequency-hopping separations greater than 0.15, hardly significantPeer ReviewedPostprint (published version

Trellis-coded 8-DPSK with postdetection combining diversity for digital land mobile radio

The performance of rate 2/3 postdetection combining diversity TCM-8DPSK systems is analyzed. A simulated Rayleigh mobile radio channel and the presence of cochannel interferers are assumed. Only the case where an ideal interleaving/deinterleaving process is used to further combat the Rayleigh fading is considered. Bit error rate (BER) is obtained through computer simulation as a function of signal-to-noise ratio (SNR) and carrier-to-interference average power ratio. Results obtained for the QDPSK and TCM-8DPSK schemes are considered as a reference to determine the performance improvements introduced by the coding diversity set-upPeer ReviewedPostprint (published version

Switched-diversity trellis-coded 8-DPSK for mobile radio applications

Peer ReviewedPostprint (published version

Downlink scheduling and resource allocation for 5G MIMO-multicarrier: OFDM vs FBMC/OQAM

OAPA The definition of the next generation of wireless communications, so-called 5G networks, is currently underway. Among many technical decisions, one that is particularly fundamental is the choice of the physical layer modulation format and waveform, an issue for which several alternatives have been proposed. Two of the most promising candidates are: (i) orthogonal frequency division multiple (OFDM), a conservative proposal that builds upon the huge legacy of 4G networks, and (ii) filterbank multicarrier/offset quadrature amplitude modulation (FBMC/OQAM), a progressive approach that in frequency selective channels sacrifices subcarrier orthogonality in lieu of an increased spectral efficiency. The comparative merits of OFDM and FBMC/OQAM have been well investigated over the last few years but mostly, from a purely physical layer point of view and largely neglecting how the physical layer performance translates into user-relevant metrics at the upper-layers. This paper aims at presenting a comprehensive comparison of both modulation formats in terms of practical network indicators such as goodput, delay, fairness and service coverage, and under operational conditions that can be envisaged to be realistic in 5G deployments. To this end, a unifying cross-layer framework is proposed that encompasses the downlink scheduling and resource allocation procedures and that builds upon a model of the queueing process at the data-link control layer and a physical layer abstraction that can be chosen to model either OFDM or FBMC/OQAM. Extensive numerical results conclusively demonstrate that most of the apriori advantages of FBMC/OQAM over OFDM do indeed translate into improved network indicators, that is, the increase in spectral efficiency achieved by FBMC/OQAM makes up for the distortion caused by the loss of orthogonality.Peer ReviewedPostprint (published version

Design and implementation of a wide-band real-time mobile channel emulator

A new wide-band mobile channel emulator for the CODIT project is designed and implemented. The UMTS code-division testbed (CODIT R2020) is a research project within the European RACE-II program set up by the Commission of the European Community. Our goal is to be able to simulate in the laboratory, in real time, the multipath propagation found in the mobile radio channel. As code-division multiple access (CDMA) is the access technique within the CODIT project, it was realized that the channel emulator must have simultaneously good delay resolution between propagation paths and long duration of the impulse response. These considerations led to a very flexible channel emulator specifically designed to host the new wide-band channel models developed within the CODIT project. Our emulator features three independent inputs and two outputs, up to 20 complex propagation paths, 10-MHz radio frequency (RF) bandwidth, a delay resolution of 50 ns, and a maximum duration of the channel impulse response of 80 μs. Starting with an explanation of the global structure of the new channel emulator, we derive the optimum design of the interpolation procedures and present the main implementation issues arising from our initial architecture. Finally, we report the results of the laboratory tests of the first prototype of the channel emulator.Peer Reviewe

Scalable cell-free massive MIMO networks with LEO satellite support

This paper presents an integrated network architecture combining a cell-free massive multiple-input multiple-output (CF-M-MIMO) terrestrial layout with a low Earth orbit satellite segment where the scalability of the terrestrial segment is taken into account. The main purpose of such an integrated scheme is to transfer to the satellite segment those users that somehow limit the performance of the terrestrial network. Towards this end, a correspondingly scalable technique is proposed to govern the ground-to-satellite user diversion that can be tuned to different performance metrics. In particular, in this work the proposed technique is configured to result in an heuristic that improves the minimum per-user rate and the sum-rate of the overall network. Simulation results serve to identify under which conditions the satellite segment can become an attractive solution to enhance users’ performance. Generally speaking, although the availability of the satellite segment always leads to an improvement of users’ rates, it is in those cases where the terrestrial CF-M-MIMO network exhibits low densification traits that the satellite backup becomes crucial.This work was supported in part by the Agencia Estatal de Investigación, Ministerio de Ciencia e Innovación (MCIN/AEI/10.13039/501100011033) through the R+D+i Project under Grant PID2020-115323RB-C32 and Grant PID2020-115323RB-C31; and in part by the Centre Tecnológic de Telecomunicacions de Catalunya Researchers through the Grant from the Spanish Ministry of Economic Affairs and Digital Transformation and the European Union-NextGenerationEU under Grant UNICO-5G I+D/AROMA3D-Hybrid TSI-063000-2021-71.Peer ReviewedPostprint (published version

Recent Advances on Telematics Engineering

[EN] This Special Issue includes extended versions of selected papers from the XII Jornadas de Ingeniería Telemática (JITEL 2015), that took place in Palma, Spain, from October 14th to 16th, 2015. These papers underwent a rigorous review process, ensuring that they present enough new material so as to be considered original contributions while avoiding self-plagiarism.Agüero Calvo, R.; Payeras Capellà, MM.; Femenias Nadal, G.; Lloret, J. (2016). Recent Advances on Telematics Engineering. Network Protocols and Algorithms. 8(1):1-6. https://doi.org/10.5296/npa.v8i1.9365S168

Sistema TDMA-FH-TCM-8PSK en un entorno de comunicaciones móviles celulares de banda ancha

In this paper we propase a TOMA Slow Frequency Hopping-Trellis Coded BPSK scheme for wideband cellular mobile communications. TCM wilh channel interleaving allows us to achieve coding gain without bandwith increase on Rayleigh fading channels with AWGN, and FH provides the intrinsic frequency divetsity to combat the Rayleigh fading. The dynamic multipath radio channel has been simulated by means of a simple two-ray model wilh a delay spread higher than the in verse of the transmission rate. Instead of a conventional Viterbi algorithm, a Near Maximum Likelihood detector with a good performance/complexiry tradeoff has been used to avoid the effects of linear intersymbol interference (ISI).Peer ReviewedPostprint (published version

Sistema TDMA-FH-TCM-8PSK en un entorno de comunicaciones móviles celulares de banda ancha

In this paper we propase a TOMA Slow Frequency Hopping-Trellis Coded BPSK scheme for wideband cellular mobile communications. TCM wilh channel interleaving allows us to achieve coding gain without bandwith increase on Rayleigh fading channels with AWGN, and FH provides the intrinsic frequency divetsity to combat the Rayleigh fading. The dynamic multipath radio channel has been simulated by means of a simple two-ray model wilh a delay spread higher than the in verse of the transmission rate. Instead of a conventional Viterbi algorithm, a Near Maximum Likelihood detector with a good performance/complexiry tradeoff has been used to avoid the effects of linear intersymbol interference (ISI).Peer Reviewe

Desarrollo de un modem Fh- TCM-8 DPSK basado en el TMS320C30 para comunicaciones móviles

This paper describes the real-time all-digital implementation of a FDMA/TDMA Slow Frcquency Hopping-Trellis Coded 8DPSK modem for operation in narrow band indoor mobile radio environments. The modem architecture as well as sorne of the signa! processing techniques employed in the modero to counteract the indoor modile radio channel impairrnents, principally multipath Rayleigh fading, are described.Peer Reviewe