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Multiple-Relay Slotted ALOHA: Performance Analysis and Bounds

Andrea Munari, Visiting Senior Researcher, Institute of Communications and Navigation, German Aerospace Center (DLR), Munich, Germany
4 July 2019 -
1:00pm to 2:00pm

 MR-1S1 [Torres] & MR-1S3 [Quevedo], IMDEA Networks Institute, Avda. del Mar Mediterráneo 22, 28918 Leganés (Madrid)

Wireless random access protocols are attracting a revived research interest as a simple yet effective solution for machine-type communications. In the quest to improve reliability and spectral efficiency of such schemes, otherwise beset by collisions, the use of multiple receivers has recently emerged as a promising technique.

In this talk, we study the potential of this approach considering a population of users that transmit data packets following a simple slotted ALOHA policy to a set of non-cooperative receivers or relays (uplink phase). These, in turn, independently forward - part of - what decoded towards a collecting sink (downlink phase). For an on-off fading channel model, we provide exact and compact expressions for uplink throughput and packet loss rate for an arbitrary number of relays, characterising the benefits of multi-receiver schemes. Moreover, a lower bound on the minimum amount of downlink resources needed to deliver with high probability all information collected on the uplink is provided, and is shown to be achievable via random linear coding when no constraints in terms of latency are set. We further discuss a family of simple relay forwarding policies that require no packet-level coding, and present their performance based on the amount of available downlink resources. The behaviour of both random linear coding and simplified policies is also characterised when receivers are equipped with finite buffers, revealing non-trivial tradeoffs.

About Andrea Munari

Andrea Munari received the Laurea degree (M.S. equivalent) and the Ph.D. in Telecommunications Engineering from the University of Padova, Italy, in 2006 and 2010, respectively. In 2007 he joined IBM Research in Zurich, Switzerland, working on the design, analysis and implementation of energy efficient routing protocols for wireless sensor networks. In 2010 he was a research fellow at the University of Padova, and in 2011 he joined the Corp. R&D division of Qualcomm Inc. in San Diego, California, focusing on network coding techniques for LTE cellular scenarios. From 2014 to 2018 he held a senior researcher and lecturer position at the Institute of Networked Systems of RTWH Aachen University.  Currently, he is with the Institute of Communications and Navigation of the German Aerospace Center (DLR),  His main research interests include design and modelling of medium access techniques, satellite and in-band full-duplex communications, as well as radar networks. His main research interests include design and modelling of medium access techniques for wireless systems, with focus on satellite and in-band full-duplex communications, as well as radar networks. 

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This event will be conducted in English