879 research outputs found
Optimizing Average-Maximum TTR Trade-off for Cognitive Radio Rendezvous
In cognitive radio (CR) networks, "TTR", a.k.a. time-to-rendezvous, is one of
the most important metrics for evaluating the performance of a channel hopping
(CH) rendezvous protocol, and it characterizes the rendezvous delay when two
CRs perform channel hopping. There exists a trade-off of optimizing the average
or maximum TTR in the CH rendezvous protocol design. On one hand, the random CH
protocol leads to the best "average" TTR without ensuring a finite "maximum"
TTR (two CRs may never rendezvous in the worst case), or a high rendezvous
diversity (multiple rendezvous channels). On the other hand, many
sequence-based CH protocols ensure a finite maximum TTR (upper bound of TTR)
and a high rendezvous diversity, while they inevitably yield a larger average
TTR. In this paper, we strike a balance in the average-maximum TTR trade-off
for CR rendezvous by leveraging the advantages of both random and
sequence-based CH protocols. Inspired by the neighbor discovery problem, we
establish a design framework of creating a wake-up schedule whereby every CR
follows the sequence-based (or random) CH protocol in the awake (or asleep)
mode. Analytical and simulation results show that the hybrid CH protocols under
this framework are able to achieve a greatly improved average TTR as well as a
low upper-bound of TTR, without sacrificing the rendezvous diversity.Comment: Accepted by IEEE International Conference on Communications (ICC
2015, http://icc2015.ieee-icc.org/
Critically evaluate how and why suppliers circumvent complaince codes. To what extend are social audit frameworks effective in managing sourcing risks.
Sustainability and outsourcing management are both complex areas, but the combination of both is where business, value creation and competitiveness meet reality. It is difficult to manage increasing globalised supply chains.
The purpose of this management project is to critically examine the supply chain risk management system of many branded companies or retailers, particularly, social auditing (SA) or called social assessment, as to its effectiveness and appropriateness in managing sourcing risks.
From the literature review and some consultations, the characteristic of SA is one of the best instruments to measure a company's integrity and genuine activities. However, it has drawbacks of auditor quality, risks of biased information and most important, the manipulative data. The project proceeds from a case study referring to understand why and how factory managers circumvent the codes, and how to improve the SA framework in order to enhance the sustainability of sourcing practices.
The project found out four common manipulation techniques in exercise, namely bribery, falsified record, worker coaching and threatening and complicit coalition. Furthermore, the fundamental problem is the contradiction between the buyer principles and their ethical standards, which needs thorough scrutiny before implementing the social audit assessment
Mining frequent sequences using itemset-based extension
In this paper, we systematically explore an itemset-based extension approach for generating candidate sequence which contributes to a better and more straightforward search space traversal performance than traditional item-based extension approach. Based on this candidate generation approach, we present FINDER, a novel algorithm for discovering the set of all frequent sequences. FINDER is composed oftwo separated steps. In the first step, all frequent itemsets are discovered and we can get great benefit from existing efficient itemset mining algorithms. In the second step, all frequent sequcnces with at least two frequent itemsets are detected by combining depth-first search and item set-based extension candidate generation together. A vertical bitmap data representation is adopted for rapidly support counting reason. Several pruning strategies are used to reduce the search space and minimize cost of computation. An extensive set ofexperiments demonstrate the effectiveness and the linear scalability of proposed algorithm
Annual Report of the Commission of the Department of Public Utilities for the Year Ending November 30, 1937
Millimeter wave (mmWave) communications provide great potential for
next-generation cellular networks to meet the demands of fast-growing mobile
data traffic with plentiful spectrum available. However, in a mmWave cellular
system, the shadowing and blockage effects lead to the intermittent
connectivity, and the handovers are more frequent. This paper investigates an
``all-mmWave'' cloud radio access network (cloud-RAN), in which both the
fronthaul and the radio access links operate at mmWave. To address the
intermittent transmissions, we allow the mobile users (MUs) to establish
multiple connections to the central unit over the remote radio heads (RRHs).
Specifically, we propose a multipath transmission framework by leveraging the
``all-mmWave'' cloud-RAN architecture, which makes decisions of the RRH
association and the packet transmission scheduling according to the
time-varying network statistics, such that a MU experiences the minimum
queueing delay and packet drops. The joint RRH association and transmission
scheduling problem is formulated as a Markov decision process (MDP). Due to the
problem size, a low-complexity online learning scheme is put forward, which
requires no a priori statistic information of network dynamics. Simulations
show that our proposed scheme outperforms the state-of-art baselines, in terms
of average queue length and average packet dropping rate
From Authority-Respect to Grassroots-Dissent: Degree-Weighted Social Learning and Convergence Speed
Opinions are influenced by neighbors, with varying degrees of emphasis based
on their connections. Some may value more connected neighbors' views due to
authority respect, while others might lean towards grassroots perspectives. The
emergence of ChatGPT could signify a new ``opinion leader'' whose views people
put a lot of weight on. This study introduces a degree-weighted DeGroot
learning model to examine the effects of such belief updates on learning
outcomes, especially the speed of belief convergence. We find that greater
respect for authority doesn't guarantee faster convergence. The influence of
authority respect is non-monotonic. The convergence speed, influenced by
increased authority-respect or grassroots dissent, hinges on the unity of elite
and grassroots factions. This research sheds light on the growing skepticism
towards public figures and the ensuing dissonance in public debate
Antiperovskite Li3OCl Superionic Conductor Films for Solid-State Li-Ion Batteries.
Antiperovskite Li3OCl superionic conductor films are prepared via pulsed laser deposition using a composite target. A significantly enhanced ionic conductivity of 2.0 × 10-4 S cm-1 at room temperature is achieved, and this value is more than two orders of magnitude higher than that of its bulk counterpart. The applicability of Li3OCl as a solid electrolyte for Li-ion batteries is demonstrated
Computation Offloading in Beyond 5G Networks: A Distributed Learning Framework and Applications
Facing the trend of merging wireless communications and multi-access edge
computing (MEC), this article studies computation offloading in the beyond
fifth-generation networks. To address the technical challenges originating from
the uncertainties and the sharing of limited resource in an MEC system, we
formulate the computation offloading problem as a multi-agent Markov decision
process, for which a distributed learning framework is proposed. We present a
case study on resource orchestration in computation offloading to showcase the
potentials of an online distributed reinforcement learning algorithm developed
under the proposed framework. Experimental results demonstrate that our
learning algorithm outperforms the benchmark resource orchestration algorithms.
Furthermore, we outline the research directions worth in-depth investigation to
minimize the time cost, which is one of the main practical issues that prevent
the implementation of the proposed distributed learning framework
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