Peak age of information in slotted ALOHA network

<p>In this paper, we concentrate on the peak age of information (PAoI) in a discrete-time slotted ALOHA network comprised of <i>M</i> buffer-less nodes, capable of keeping just one packet at each time. In this network, whenever some nodes transmit their packets simultaneously, a collision happens, thus there is interaction among queues and transmission delay of a packet might prolong more than one slot. The packets are generated at each node stochastically and independently. The nodes follow preemptive queueing policy. In this network, we propose a new trellis-based analytical model to represent the interaction among queues and derive exact average PAoI in closed form. Furthermore, we find average PAoI-constrained regions and minimize average PAoI for a symmetric network, numerically. As a byproduct of our analysis, the achievable throughput region of two slotted ALOHA networks with unlimited buffer and buffer-less nodes are compared. We observe that the latter is superior not only in AoI, but also in achievable throughput region. Simulation results confirm our analysis.</p>

Peak age of information in slotted ALOHA network

<p>In this paper, we concentrate on the peak age of information (PAoI) in a discrete-time slotted ALOHA network comprised of <i>M</i> buffer-less nodes, capable of keeping just one packet at each time. In this network, whenever some nodes transmit their packets simultaneously, a collision happens, thus there is interaction among queues and transmission delay of a packet might prolong more than one slot. The packets are generated at each node stochastically and independently. The nodes follow preemptive queueing policy. In this network, we propose a new trellis-based analytical model to represent the interaction among queues and derive exact average PAoI in closed form. Furthermore, we find average PAoI-constrained regions and minimize average PAoI for a symmetric network, numerically. As a byproduct of our analysis, the achievable throughput region of two slotted ALOHA networks with unlimited buffer and buffer-less nodes are compared. We observe that the latter is superior not only in AoI, but also in achievable throughput region. Simulation results confirm our analysis.</p>

Coherent Contention Resolution Diversity Slotted ALOHA: An Improved Multiple Access Method for Satellite IoT System

For Beyond 5G/6G system, satellite communication systems become an effective component of the space and terrestrial integrated network. Among typical applications, massive Machine Type of Communication (mMTC) is a promising and challenging application. The demands of low power consumption and light signaling make random access methods as the potential solution. Up to now, contention resolution-based ALOHA methods, such as contention resolution diversity slotted ALOHA (CRDSA), improve the throughput significantly. However, its throughput will meet the inflection point soon with the normalized load increasing since collisionless packets are hardly existing. In fact, the diversity of transmitting packets is not utilized totally. In this paper, an improved random access method, named coherent CRDSA method (C-CRDSA), is proposed. It accumulates replicated packets coherently at receiver and further improve the throughput over CRDSA. Detailed derivations and simulations are given. Simulation results corroborate the effectiveness of the proposed method.