Browsing by Subject "Irregular repetition slotted ALOHA"

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    An energy-efficient feedback-aided irregular repetition slotted ALOHA scheme and its asymptotic performance analysis
    (Institute of Electrical and Electronics Engineers, 2023-05-12) Haghighat, Javad; Duman, Tolga Mete
    We present a decentralized feedback-aided Irregular Repetition Slotted ALOHA (IRSA) scheme that improves energy efficiency. The scheme divides the IRSA MAC frame into several sub-frames, performs tentative decoding after each sub-frame, and uses limited feedback for users to detect whether their packet has been decoded at the receiver. Once a user detects that its packet is decoded, it stops transmitting its remaining replicas, resulting in a decrease in the expected number of transmitted packet replicas and an increase in energy efficiency. For analysis, we employ a graph-based representation of the successive interference cancellation decoding of IRSA. We prove several results for a fixed graph, and extend our analysis to a randomly selected graph to derive the efficiency of the proposed scheme. Numerical results show that the proposed feedback-aided IRSA solution outperforms standard IRSA and performs similarly to the best known Coded Slotted ALOHA (CSA) schemes. Also, the proposed scheme achieves efficiencies significantly larger than the threshold of 0.5 which is an upper bound for standard IRSA.
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    Irregular repetition slotted ALOHA with energy harvesting nodes
    (IEEE, 2019-09) Demirhan, Umut; Duman, Tolga M.
    We propose an irregular repetition slotted ALOHA (IRSA) based uncoordinated random access scheme for energy harvesting (EH) nodes. Specifically, we consider the case in which each user has a battery that is recharged with harvested energy from the environment in a probabilistic manner. We analyze this scheme starting with a unit-sized battery at the nodes and extend the analysis to the case of a finite-sized battery. For both scenarios, we derive the asymptotic throughput expressions and obtain the optimized probability distributions for the number of packet replicas of the users. We demonstrate that for the case of IRSA with EH nodes, these optimized distributions perform considerably better than the alternatives, including slotted ALOHA (SA), contention resolution diversity slotted ALOHA (CRDSA), and IRSA, which do not take into account the EH process for both asymptotic and finite frame length scenarios.