Publications de Télécom bretagne

Throughput Performance of Time- and Frequency-Asynchronous ALOHA



Type de document

Communication dans une conférence avec acte


SCC 2017 : 11th International ITG Conference on Systems, Communications and Coding, IEEE, 06-09 february 2017, Hambourg, Germany, 2017, ISBN 978-3-8007-4362-9




Time- and Frequency-Asynchronous Aloha (TFAA) is a random access scheme in which packet transmissions are neither coordinated in the time domain nor in the frequency domain. Its original interest lies in that it allows to reduce the transmission data rate down to levels that cannot be achieved in systems where precise channel boundaries must be respected. Consequently, the transmission power can be reduced and/or the communication range increased accordingly, which can be particularly attractive in power constrained wireless applications. Thus, TFAA can be considered as an alternative to spread spectrum communications. In this paper, we evaluate the throughput performance of TFAA over both the collision and capture channel models. For the collision channel, an exact, closed-form expression is derived, while for the capture model the exact throughput is computed through a semi-analytical approach and validated by computer simulation. In the latter case, our results show that the performance loss incurred by adding an additional degree of asynchronism is rather small. Further, TFAA can be significantly improved by the use of low-rate forward error correction. These results open new perspectives for the development of high-throughput, asynchronous random access protocols.


1 : CSU - Centre Spatial Universitaire - Université de Montpellier (Université de Montpellier)
2 : MO(TB) - Dépt. Micro-Ondes (Institut Mines-Télécom-Télécom Bretagne-UEB)
3 : Lab-STICC(TB) - Laboratoire en sciences et technologies de l'information, de la communication et de la connaissance (UMR CNRS 6285 - Télécom Bretagne - Université de Bretagne Occidentale - Université de Bretagne Sud - ENSTA Bretagne - Ecole Nationale d'ingénieurs de Brest)

Mots clés

Satellite communications, M2M



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