On Throughput Maximization of Grant-Free Access with Reliability-Latency Constraints

Enabling autonomous driving and industrial automation with wireless networks poses many challenges, which are typically abstracted through reliability and latency requirements. One of the main contributors to latency in cellular networks is the reservation-based access, which involves lengthy and resource-inefficient signaling exchanges. An alternative is to use grant-free access, in which there is no resource reservation. A handful of recent works investigated how to fulfill reliability and latency requirements with different flavors of grant-free solutions. However, the resource efficiency, i.e., the throughput, has been only the secondary focus. In this work, we formulate the throughput of grant-free access under reliability-latency constraints, when the actual number of arrived users or only the arrival distribution are known. We investigate how these different levels of knowledge about the arrival process influence throughput performance of framed slotted ALOHA with $K$-multipacket reception, for the Poisson and Beta arrivals. We show that the throughput under reliability-latency requirements can be significantly improved for the higher expected load of the access network, if the actual number of arrived users is known. This insight motivates the use of techniques for the estimation of the number of arrived users, as this knowledge is not readily available in grant-free access. We also asses the impact of estimation error, showing that for high reliability-latency requirements the gains in throughput are still considerable.Comment: Accepted for publication in ICC'201

Analysis of Tree-Algorithms with Multi-Packet Reception

In this paper, we analyze binary-tree algorithms in a setup in which the receiver can perform multi-packet reception (MPR) of up to and including K packets simultaneously. The analysis addresses both traffic-independent performance as well as performance under Poisson arrivals. For the former case, we show that the throughput, when normalized with respect to the assumed linear increase in resources required to achieve K-MPR capability, tends to the same value that holds for the single-reception setup. However, when coupled with Poisson arrivals in the windowed access scheme, the normalized throughput increases with K, and we present evidence that it asymptotically tends to 1. We also provide performance results for the modified tree algorithm with K-MPR in the clipped access scheme. To the best of our knowledge, this is the first paper that provides an analytical treatment and a number of fundamental insights in the performance of tree-algorithms with MPR.Comment: Published in : GLOBECOM 2020 - 2020 IEEE Global Communications Conferenc

High-K volcanism in the Afyon region, western Turkey: from Si-oversaturated to Si-undersaturated volcanism

Volcanic rocks of the Afyon province (eastern part of western Anatolia) make up a multistage potassic and ultrapotassic alkaline series dated from 14 to 12 Ma. The early-stage Si-oversaturated volcanic rocks around the Afyon city and further southward are trachyandesitic volcanic activity (14.23 ± 0.09 Ma). Late-stage Si-undersaturated volcanism in the southernmost part of the Afyon volcanic province took place in three episodes inferred from their stratigraphic relationships and ages. Melilite– leucitites (11.50 ± 0.03 Ma), spotted rachyandesites, tephryphonolites and lamproites (11.91 ± 0.13 Ma) formed in the first episode; trachyandesites in the second episode and finally phonotephrites, phonolite, basaltic trachyandesites and nosean-bearing trachyandesites during the last episode. The parameter Q [normative q-(ne + lc + kls + ol)] of western Anatolia volcanism clearly decreased southward with time becoming zero in the time interval 10–15 Ma. The magmatism experienced a sudden change in the extent of Si saturation after 14 Ma, during late-stage volcanic activity of Afyon volcanic province at around 12 Ma, though there was some coexistence of Si-oversaturated and Si-undersaturated magmas during the whole life of Afyon volcanic province

Short Frame Length Approximation for IRSA

In this letter, we propose a short-frame (SF) approximation for the packet loss rate of Irregular Repetition Slotted ALOHA (IRSA) particularly suitable for very short frames, up to 50 slots. The reason for limiting the frame size is to allow low-latency communications, a typical requirement in Industrial Internet of Things (IIoT) applications. We extend the approximation of [1] (named EF) through a recursive evaluation of inter-related stopping sets (STs). The tighter approximation yields the user degree distribution that minimizes the packet loss rate (PLR). For a scenario with 10 slots and 5 users, the degree distribution optimized adopting the SF approximation results in a 20% lower PLR compared to the one optimized with the EF approximation

System Level Integration of Irregular Repetition Slotted ALOHA for Industrial IoT in 5G New Radio

Automation is a key part of the new industrial revolution, that will be enabled by the deployment of thousands of sensors and actuators. The flexible deployment of these devices requires wireless connectivity which is labeled as industrial internet of things, IIoT. The sporadic activity pattern of IIoT devices naturally suggest the use of random access techniques, albeit posing new and unexplored challenges for the current wireless networks. On top of the demand for new access protocols, the latency-reliability requirements further challenge the existing random access protocols. In this work we investigate the adaptation of a well known modern random access algorithm, Irregular Repetition Slotted ALOHA (IRSA) to IIoT in 5G New Radio. The key contribution of the paper is the proposed system level protocol, Adaptive-Multichannel IRSA, that can fulfill the latency-reliability requirements. On top of this, the definition and solution of the resource allocation problem as a resource efficiency optimization guarantees that the algorithm minimizes the system resources. We show that for a set of specific requirements, AMC-IRSA can fulfill the requirements in an a lot resource efficient manner. Lastly, we analyze most critical parameters to consider for integration of IRSA for 5G NR

A novel green and one-step electrochemical method for production of sulfur-doped graphene powders and their performance as an anode in Li-ion battery

Graphene-based negative electrodes in lithium-ion batteries have recently been the focus of interest. In this study, sulfur (S)–doped graphene powders in different functionality have been prepared in one step by using Yucel’s method for the first time in the literature and they have been used as anode materials of Li-ion batteries. By changing the scanned potential during the preparation of S-doped graphene powders, the graphenic surface is covalently doped by –C-S-C- and –C-SOx-C- (x:2, 3) groups at different amount. When the potential has been scanned in wider potential range (− 1.0 and 2.5 V), 48 sp2-hybridized carbon rings have been determined on the powders by using Raman analysis. It is the lowest as 16 for graphenic powder prepared at narrower potential range (1.5 and 2.5 V) and chronoamperometric method. S-doped graphene powders have been investigated by microscopic methods. Electrochemical properties of the prepared S-doped graphene powders and their potential use in Li-ion batteries have been assessed. At a 50-mA/g current density, the 915-mAh/g specific capacity has been determined as the highest discharge capacity in the powder which was prepared by the chronoamperometric method. Specific capacities of 710 mAh/g, 594 mAh/g, and 642 mAh/g have been observed in the powders prepared between − 1.0–(+ 2.5 V), 0.6–(+ 2.5 V), and 1.5–(+ 2.5 V) samples, respectively. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature