Dual Auction Mechanism for Transaction Forwarding and Validation in Complex Wireless Blockchain Network

In traditional blockchain networks, transaction fees are only allocated to full nodes (i.e., miners) regardless of the contribution of forwarding behaviors of light nodes. However, the lack of forwarding incentive reduces the willingness of light nodes to relay transactions, especially in the energy-constrained Mobile Ad Hoc Network (MANET). This paper proposes a novel dual auction mechanism to allocate transaction fees for forwarding and validation behaviors in the wireless blockchain network. The dual auction mechanism consists of two auction models: the forwarding auction and the validation auction. In the forwarding auction, forwarding nodes use Generalized First Price (GFP) auction to choose transactions to forward. Besides, forwarding nodes adjust the forwarding probability through a no-regret algorithm to improve efficiency. In the validation auction, full nodes select transactions using Vickrey-Clarke-Grove (VCG) mechanism to construct the block. We prove that the designed dual auction mechanism is Incentive Compatibility (IC), Individual Rationality (IR), and Computational Efficiency (CE). Especially, we derive the upper bound of the social welfare difference between the social optimal auction and our proposed one. Extensive simulation results demonstrate that the proposed dual auction mechanism decreases energy and spectrum resource consumption and effectively improves social welfare without sacrificing the throughput and the security of the wireless blockchain network

SoK: Diving into DAG-based Blockchain Systems

Blockchain plays an important role in cryptocurrency markets and technology services. However, limitations on high latency and low scalability retard their adoptions and applications in classic designs. Reconstructed blockchain systems have been proposed to avoid the consumption of competitive transactions caused by linear sequenced blocks. These systems, instead, structure transactions/blocks in the form of Directed Acyclic Graph (DAG) and consequently re-build upper layer components including consensus, incentives, \textit{etc.} The promise of DAG-based blockchain systems is to enable fast confirmation (complete transactions within million seconds) and high scalability (attach transactions in parallel) without significantly compromising security. However, this field still lacks systematic work that summarises the DAG technique. To bridge the gap, this Systematization of Knowledge (SoK) provides a comprehensive analysis of DAG-based blockchain systems. Through deconstructing open-sourced systems and reviewing academic researches, we conclude the main components and featured properties of systems, and provide the approach to establish a DAG. With this in hand, we analyze the security and performance of several leading systems, followed by discussions and comparisons with concurrent (scaling blockchain) techniques. We further identify open challenges to highlight the potentiality of DAG-based solutions and indicate their promising directions for future research.Comment: Full versio

Essays in Behavioral Labor Economics

This dissertation consists of three essays in Behavioral Labor Economics. The first two chapters contribute to the understanding of non-standard preferences of individuals in the workplace, and the third studies how cultural values affect firm behavior. The first chapter studies the incentive effects of top-down favoritism in employee promotions on workers and its organization-wide productivity consequences, and provides evidence on social preferences and fairness concerns among co-workers. Using data from public high schools in four Chinese cities, I first show that teachers with hometown or college ties to the school principal are twice as likely to be promoted, after controlling for characteristics on their application profiles and their value-added in teaching. I then use the results from a survey in which I asked teachers to select anonymous peers to promote from a pool of applicants applying for promotion to infer each teacher’s revealed fairness views regarding promotion qualifications. Contrasting these with actual past promotions in turn allows me to measure if and when a teacher might have observed unfair promotions in her own school in the past. Exposure to unfair promotions adversely affects non-applicant teachers’ output, lowering their value-added and raising the probability that high-value-added teachers quit. The value-added effect appears to be driven primarily by teachers’ social preferences for peer workers and the consequent erosion of their morale when peers suffer unfair treatment, while the quitting effect comes mainly from non-favored prospective applicants’ career concerns as they learn about the principal’s bias and leave due to poor promotion prospects. These adverse spillover incentive effects lead to a substantial reduction in school-wide output, which is only slightly mitigated by increased productivity among favored teachers. Finally, a transparency reform that required principals to disclose to their peers the profiles of teachers that apply for promotion reduced the principals’ bias and improved the overall productivity of schools. The second chapter documents daily targeting behavior in workers’ labor supply decisions. Using a novel dataset on the daily production of a group of piece-rate manufacturing workers combined with their quasi-random daily income shocks from lunch break card game gambling, I show that the workers’ afternoon labor supply responds negatively to instantaneously-paid quasi-random gambling income, although wages are paid monthly. The workers’ labor supply decisions were consistent with daily mental accounting and reference dependence where the target was set on the sum of the face - valued daily (receivable) labor and (paid) unearned income, as opposed to the neoclassical model of inter-temporal labor supply. Estimation of two structural models of daily labor supply yields a coefficient of loss aversion parameter of 1.8 to 2.0, significantly different from the neoclassical value of 1; and individual specific loss aversion structural estimates correlate positively with survey measures. Using estimated preference parameters, I back out the implied total wage elasticity of daily labor supply as well as a sizable negative reference-dependent component of it. This study overcomes the common identification issues in the daily labor supply literature by exploiting high-frequency, actively taken-up and unanticipated income shifters that are independent of other labor supply and demand confounders. In the third chapter, we show that many employers anchor their wages at establishments outside of the home region to headquarter levels, and begin to study the consequences. Our analysis makes use of an unusual 2005-2015 establishment-year level dataset of average wages by narrowly-defined occupation. The dataset covers 1,800 large employers that span many different sectors and each operate in a subset of 170 observed capital city locations. We show that, across the occupational skill range—including for low-skill support staff— the average wage multinationals pay domestic workers in a given occupation at foreign establishments is robustly and remarkably highly correlated with the average wage they pay workers in the same occupation in the home country. We then instrument for headquarter wage levels with changes in home country minimum wage laws and show that externally imposed wage increases at home causally raise wages abroad. The relationships we establish between headquarters’ and their foreign establishments’ wage levels and wage changes are both driven by employers from inequality-averse societies. Occupations are more (less) likely to be removed from, and less (more) likely to be added to the foreign establishments (headquarters) of such employers after a (minimum wage-induced) wage increase originating at the headquarter. Our results point towards the existence of “wage cultures” that influence how production is organized across space

MediaSync: Handbook on Multimedia Synchronization

This book provides an approachable overview of the most recent advances in the fascinating field of media synchronization (mediasync), gathering contributions from the most representative and influential experts. Understanding the challenges of this field in the current multi-sensory, multi-device, and multi-protocol world is not an easy task. The book revisits the foundations of mediasync, including theoretical frameworks and models, highlights ongoing research efforts, like hybrid broadband broadcast (HBB) delivery and users' perception modeling (i.e., Quality of Experience or QoE), and paves the way for the future (e.g., towards the deployment of multi-sensory and ultra-realistic experiences). Although many advances around mediasync have been devised and deployed, this area of research is getting renewed attention to overcome remaining challenges in the next-generation (heterogeneous and ubiquitous) media ecosystem. Given the significant advances in this research area, its current relevance and the multiple disciplines it involves, the availability of a reference book on mediasync becomes necessary. This book fills the gap in this context. In particular, it addresses key aspects and reviews the most relevant contributions within the mediasync research space, from different perspectives. Mediasync: Handbook on Multimedia Synchronization is the perfect companion for scholars and practitioners that want to acquire strong knowledge about this research area, and also approach the challenges behind ensuring the best mediated experiences, by providing the adequate synchronization between the media elements that constitute these experiences

Incentive-driven QoS in peer-to-peer overlays

A well known problem in peer-to-peer overlays is that no single entity has control over the software, hardware and configuration of peers. Thus, each peer can selfishly adapt its behaviour to maximise its benefit from the overlay. This thesis is concerned with the modelling and design of incentive mechanisms for QoS-overlays: resource allocation protocols that provide strategic peers with participation incentives, while at the same time optimising the performance of the peer-to-peer distribution overlay. The contributions of this thesis are as follows. First, we present PledgeRoute, a novel contribution accounting system that can be used, along with a set of reciprocity policies, as an incentive mechanism to encourage peers to contribute resources even when users are not actively consuming overlay services. This mechanism uses a decentralised credit network, is resilient to sybil attacks, and allows peers to achieve time and space deferred contribution reciprocity. Then, we present a novel, QoS-aware resource allocation model based on Vickrey auctions that uses PledgeRoute as a substrate. It acts as an incentive mechanism by providing efficient overlay construction, while at the same time allocating increasing service quality to those peers that contribute more to the network. The model is then applied to lagsensitive chunk swarming, and some of its properties are explored for different peer delay distributions. When considering QoS overlays deployed over the best-effort Internet, the quality received by a client cannot be adjudicated completely to either its serving peer or the intervening network between them. By drawing parallels between this situation and well-known hidden action situations in microeconomics, we propose a novel scheme to ensure adherence to advertised QoS levels. We then apply it to delay-sensitive chunk distribution overlays and present the optimal contract payments required, along with a method for QoS contract enforcement through reciprocative strategies. We also present a probabilistic model for application-layer delay as a function of the prevailing network conditions. Finally, we address the incentives of managed overlays, and the prediction of their behaviour. We propose two novel models of multihoming managed overlay incentives in which overlays can freely allocate their traffic flows between different ISPs. One is obtained by optimising an overlay utility function with desired properties, while the other is designed for data-driven least-squares fitting of the cross elasticity of demand. This last model is then used to solve for ISP profit maximisation