3,911 research outputs found
np-CECADA: Enhancing Ubiquitous Connectivity of LoRa Networks
No full textLong Range Wide Area Networks (LoRaWAN) offer ubiquitous communications for The Internet of Things (IoT). However, there are many challenges in rolling out LoRaWAN - mainly scalability, energy efficiency, Packet Reception Ratio (PRR), and keeping the channel access as simple as unslotted ALOHA. To this end, we design non-persistent Capture Effect Channel Activity Detection Algorithm (np-CECADA), which is a novel, distributed protocol for the MAC layer of LoRaWAN. It utilizes Channel Activity Detection (CAD), which is a built-in imperfect mechanism for channel sensing and minimal feedback from the gateways. In np-CECADA each device independently adapts backoff times based on the traffic in its vicinity and the transmission power based on the heuristically inferred probability of capturing the channel. To achieve this, first, we carried out an extensive on-field evaluation to measure the effectiveness of CAD and capture effect in LoRa. Using them we designed np CECADA and developed ns-3 modules. Packet Reception Ratio of np-CECADA is 15.74× and 5.13× higher than vanilla LoRaWAN and p-CARMA, respectively. Channel utilization is 11.24× higher compared to LMAC. Further, on a testbed of 30 LoRa devices np-CECADA outperforms LoRaWAN up to 5 times.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Embedded System
A note on the satisfactory partition problem: Constant size requirement
No full textA satisfactory partition is a partition of the vertex set V of a graph into two subsets such that each vertex has at least as many neighbors in the subset it belongs to as in the other subset. The definition can be generalized requiring that each vertex v has at least s(v) neighbors in the subset it belongs to, for a given function s : V → N. While the complexity of the problem of deciding if a graph admits a generalized satisfactory partition has been completely analized when s(v) is a function of the node degree, the issue had left open in the case s(v) is a constant. We prove that, for any constant k ≥ 2, the problem is NP-complete when s(v) = k for any v ∈ V
P≠NP
No full textHere, the author tries to build the structure of the Theory of computation based on considering time as a fuzzy concept.
In fact, there are reasons to consider time as a fuzzy concept. In this article, the author doesn’t go to this side but note that Brower and Husserl views on the concept of time were similar [8]. Some reasons have been given for it in [3].
Throughout this article, the author presents the Theory of Computation with Fuzzy Time. Given the classic definition of Turing Machine, the concept of Time is modified to Fuzzy time. This new term calls as Theory TC* [2] and this type of computation “Fuzzy time Computation”. We have relatively large number of fundamental unsolved problems in Complexity Theory. In the new theory, some of the major obstacles and unsolved problems have been solved [2]. It should be noted that in this article, the writer considers fuzzy number associated to instants of time as a symmetric one. The point about the symmetry is in the proof of Lemma 3, although it is generalizable.
In particular, the new classes of complexity Theory, P*, NP*, BPP* in the TC* analogues to the definitions of P, NP, BPP defines as their natural alternative definition. Here, we will see P*≠ NP*, P*= BPP*. Finally, we have Theorem 4
P≠NP
No full textHere, the author tries to build the structure of the Theory of computation based on considering time as a fuzzy concept.
In fact, there are reasons to consider time as a fuzzy concept. In this article, the author doesn’t go to this side but note that Brower and Husserl views on the concept of time were similar [8]. Some reasons have been given for it in [3].
Throughout this article, the author presents the Theory of Computation with Fuzzy Time. Given the classic definition of Turing Machine, the concept of Time is modified to Fuzzy time. This new term calls as Theory TC* [2] and this type of computation “Fuzzy time Computation”. We have relatively large number of fundamental unsolved problems in Complexity Theory. In the new theory, some of the major obstacles and unsolved problems have been solved [2]. It should be noted that in this article, the writer considers fuzzy number associated to instants of time as a symmetric one. The point about the symmetry is in the proof of Lemma 3, although it is generalizable.
In particular, the new classes of complexity Theory, P*, NP*, BPP* in the TC* analogues to the definitions of P, NP, BPP defines as their natural alternative definition. Here, we will see P*≠ NP*, P*= BPP*. Finally, we have Theorem 4
NP vyhledávací problémy
No full textTitle: NP search problems Author: Tomáš Jirotka Department: Department of Algebra Supervisor: Prof. RNDr. Jan Krajíček, DrSc. Abstract: The thesis summarizes known results in the field of NP search pro- blems. We discuss the complexity of integer factoring in detail, and we propose new results which place the problem in known classes and aim to separate it from PLS in some sense. Furthermore, we define several new search problems. Keywords: Computational complexity, TFNP, integer factorization.
NP-MOVEMENT AND THE POSSESSIVE GENITIVE
No full textU članku se raspravlja o mjestu genitiva u izgradnji složenih NP te posebice o
odnosu s drugim konkurentnim sintaktičkim sredstvima. U žarištu istraživanja,
u kojem su primijenjene neke od modularnih sastavnica teorije načela i
paramatera (TNP): X'-teorija, padežna teorija i teorija tematskih uloga, nalazi
se NP-pomicanje posvojnoga genitiva s temeljno generiranog položaja na
mjesto odrednika, odnosno na projekciju gdje se nalazi posvojni sufiks. Autor
smatra kako između DP i NP u objašnjavanju toga fenomena valja uvesti novi
sloj - funkcionalnu kategoriju Poss, a NP–pomicanje objašnjava se težnjom
svake imenice da bude što bolje određena, aktualizirana. Provjerava se i utjecaj
morfosintaktičkog obilježja određenosti kod morfoloških posvojnih oblika na
druge sročne atribute.The paper discusses the place of the genitive in the derivation of complex NPs, particularly
in relation to other, competing syntactic means. The study that relies on some modular
components of the theory or principles and parametres (X' theory, case theory, and the theory
of thematic roles) focuses on the NP-movement of the possessive genitive out of the basegenerated
position into the specifier position or into the projection occupied by the
possessive suffix. The author argues that in order to explan the phenomenon a new level
should be recognized between DP and NP—the functional category Poss. NP-movement is
explained as the tendency of nouns to be as determined and actualised as possible. The
influence of the morphosyntactic property of determination of possessive forms on other
congruent attributes is examined
Minimizing the effective graph resistance by adding links is NP-hard
No full textThe effective graph resistance, also known as the Kirchhoff index, is metric that is used to quantify the robustness of a network. We show that the optimisation problem of minimizing the effective graph resistance of a graph by adding a fixed number of links, is NP-hard.Quantum & Computer EngineeringNetwork Architectures and Service
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