This thesis presents the design of a new radio modem used in Private Mobile Radio (PMR) networks. The activity was done during an internship in the lab of Leonardo S.p.a.. The aim of this work was to implement a transceiver able to increase the capacity of the entire network. In particular, of crucial importance is the transmission of Network Management Service (NMS) information also during critical operations, when the communications are continuous and the packets are full of voice datas. This radio modem must transmit two Digital Mobile Radio (DMR) radio channels simultaneously in a bandwidth of 12.5kHz and must take into account the effects of the time-varying channel in the communication environment. This thesis takes a primarily theoretical approach to the investigation of synchronization issues between a PMR transmitter and a receiver. After evaluating the best techniques to mitigate distortion effects, the implementation and the design choices of a multilevel modem for point-to-point and point-to-multipoint digital radio transmission system are explained. The modem realizes perfect time and frequency synchronization between Radio Base Stations (RBSs) to allow simulcast operation by means of an accurate time and frequency recovery from the received signal. The performance of the modem was evaluated by means of simulations carried out with random data and considering a 16-QAM signal in presence of non-ideal conditions (phase offset, frequency offset, Additive White Gaussian Noise (AWGN), attenuation and delay).
Questa tesi presenta lo sviluppo di un nuovo modem radio utilizzato nelle reti Private Mobile Radio (PMR). L'attività è stata frutto dell’esperienza di stage presso la Leonardo S.p.a.. Lo scopo di questo lavoro è implementare un ricetrasmettitore in grado di aumentare la capacità di trasmissione della rete per trasmettere le informazioni Network Management Service (NMS) anche durante lo svolgimento delle operazioni critiche, quando le comunicazioni sono continue e i pacchetti sono pieni di dati. Questo modem radio deve trasmettere due portanti radio Digital Mobile Radio (DMR) nella banda di 12.5kHz e deve tenere conto degli effetti di un canale tempo variante in un sistema di comunicazione. Inizialmente questa tesi ha un approccio teorico, rivolto all'indagine dei problemi di sincronizzazione tra un trasmettitore e un ricevitore PMR. Dopo aver fatto un'analisi sulle tecniche per ridurre gli effetti di distorsione, sono state spiegate le scelte progettuali e l'implementazione del modem multilivello per il sistema di trasmissione radio digitale punto-punto e punto-multipunto. Il modem implementato consente una perfetta sincronizzazione del tempo e della frequenza tra le stazioni radio base (RBS) per consentire il funzionamento in simulcast attraverso un perfetto recupero del tempo e della frequenza dal segnale ricevuto. Le prestazioni del modem sono state valutate attraverso simulazioni effettuate con dati casuali e considerando un segnale con modulazione 16-QAM in presenza di condizioni non ideali (offset di fase, offset di frequenza, rumore Gaussiano bianco (AWGN), attenuazione e ritardo).
Point-to-multipoint QAM radio modem over narrowband link between RBS carrying two ETSI DMR radio carriers
Chimenti, Matteo
2020/2021
Abstract
This thesis presents the design of a new radio modem used in Private Mobile Radio (PMR) networks. The activity was done during an internship in the lab of Leonardo S.p.a.. The aim of this work was to implement a transceiver able to increase the capacity of the entire network. In particular, of crucial importance is the transmission of Network Management Service (NMS) information also during critical operations, when the communications are continuous and the packets are full of voice datas. This radio modem must transmit two Digital Mobile Radio (DMR) radio channels simultaneously in a bandwidth of 12.5kHz and must take into account the effects of the time-varying channel in the communication environment. This thesis takes a primarily theoretical approach to the investigation of synchronization issues between a PMR transmitter and a receiver. After evaluating the best techniques to mitigate distortion effects, the implementation and the design choices of a multilevel modem for point-to-point and point-to-multipoint digital radio transmission system are explained. The modem realizes perfect time and frequency synchronization between Radio Base Stations (RBSs) to allow simulcast operation by means of an accurate time and frequency recovery from the received signal. The performance of the modem was evaluated by means of simulations carried out with random data and considering a 16-QAM signal in presence of non-ideal conditions (phase offset, frequency offset, Additive White Gaussian Noise (AWGN), attenuation and delay).| File | Dimensione | Formato | |
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Tesi_Matteo_Chimenti.pdf
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Executive_Summary_Matteo_Chimenti.pdf
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https://hdl.handle.net/10589/186920