Section: New Results

Internet of Things (IoT) and 5G

Efficient Random Access for 5G Systems: Coded Slotted Aloha

• Participants: Ehsan Ebrahimi Khaleghi, Cédric Adjih, Amira Alloum, Paul Mï¿œhlethaler, Vinod Kumar

Motivated by scenario requirements for 5G cellular networks, we have studied one of the candidate protocols for massive random access: the family of random access methods known asCoded Slotted ALOHA (CSA). A recent trend in research hasexplored aspects of such methods in various contexts, but oneaspect has not been fully taken into account: the impact of pathloss, which is a major design constraint in long-range wireless networks. In one article, we explored the behavior of CSA, by focusing on the path loss component correlated to the distanceto the base station. Path loss provides opportunities for capture,improving the performance of CSA. We revised methods for estimating CSA behavior, provide bounds of performance, and then,focusing on the achievable throughput, we extensively explored the key parameters, and their associated gain (experimentally). Our results shed light on the behavior of the optimal distribution of repetitions in actual wireless networks.

• Participants: Cédric Adjih, Vinod Kumar

Figure 2. Example of demodulation steps in Coded Slotted Aloha

In 2017, we implemented Coded Slotted Aloha (CSA) as a proof of concept on our FIT IoT-LAB testbed (with 20+ nodes), with 802.15.4 transmissions and using a real SDR software.

This was presented in the seminar of the GT task 2 Future Access Networks of Digicosme. It was also presented as part of the tutorial "IoT in practice" in the ANTS 2017 conference.