Token Circulation Research Articles

Efficient token circulation strategies against misers in device‐to‐device relay using token‐based incentive mechanisms

Device-to-device (D2D) relay not only broadens the service coverage of a base station (BS) but also raises network capacity. When the channel quality of a user equipment (UE) is not good, it requests another UE to relay its data from the BS. Since many UEs are owned by self-interested users, token-based incentive (TBI) mechanisms allow UEs selling and buying relay services by exchanging tokens, thereby pricking UEs on to act as relay nodes. However, such mechanisms are vulnerable to the miser problem, where malicious UEs keep collecting tokens from others but never spend tokens. Eventually, negotiable tokens will gradually decrease, so more and more UEs have very few tokens to buy relay services, which restrains D2D relay. To conquer the miser problem, this paper proposes three token circulation strategies, which tax UEs and redistribute the taxed tokens to those UEs in need. Thus, misers can be prevented from hoarding tokens and breaking a TBI mechanism. The proposed strategies need not add tokens to the network, so they will not cause inflation of tokens. Simulation results show that these strategies can keep high D2D throughput with the existence of misers, which protects TBI mechanisms and promotes the performance of D2D relay.

A self-stabilizing token circulation with graceful handover on bidirectional ring networks

A self-stabilizing token circulation with graceful handover on bidirectional ring networks

A Bayesian Regularized Neural Network for Analyzing Bitcoin Trends

Bitcoin is a decentralized digital currency without a central bank or single administrator sent from user to user on the peer-to-peer bitcoin blockchain network without intermediaries' need. In this Bitcoin trend analysis work, initial attributes are considered from five sectors based on financial, social, token, network, and that count to thirteen attributes. The thirteen attributes considered are price, volume, market cap, a mean dollar invested age, social volume, social dominance, development activity, transaction volume, token age consumed, token velocity, token circulation, market value to realized value, and realized cap. We apply the attribute selection and trend analysis mapped with potential seven attributes: Price, Volume, Market Cap, Social Dominance, Development Activity, Market Value to Realized Value & Realized Cap. We have conducted Nonlinear Autoregressive with External Input analysis considering seven attributes. The work employed three training algorithms to train a neural network as Levenberg-Marquard, Bayesian Regularization, and Scaled Conjugate Gradient algorithm. The Error histogram and regression plots results indicate that the Bayesian Regularized Neural Network is showing good performance and thus provides a better forecast.

C ANOPY

This article focuses on the new privacy challenges that arise in smart homes. Specifically, the article focuses on inferring the user’s activities—which may, in turn, lead to the user’s privacy—via inferences through device activities and network traffic analysis. We develop techniques that are based on a cryptographically secure token circulation in a ring network consisting of smart home devices to prevent inferences from device activities, via device workflow , i.e., inferences from a coordinated sequence of devices’ actuation. The solution hides the device activity and corresponding channel activities, thus preserving the individual’s activities. We also extend our solution to deal with a large number of devices and devices that produce large-sized data by implementing parallel rings. Our experiments also evaluate the performance in terms of communication overheads of the proposed approach and the obtained privacy.

Design and topological analysis of probabilistic distributed mutual exclusion algorithm with unbiased refined ordering

The applications of distributed computing systems are pervasive in nature involving multiple shared resources. The distributed mutual exclusion algorithms of various classes are employed to control concurrency of accessing shared resources maintaining data consistency. In general, the distributed mutual exclusion algorithms are designed based on fixed or dynamic graph structures formed by a set of processes, where the distributed mutual exclusion mechanisms are realized depending upon timestamp based ordering of events or by employing token circulation in the graph. On the contrary, in large scale heterogeneous distributed systems, an aggregate set of processes can be generated under special circumstances, where processes in a group are equally eligible to enter into critical section. In order to maintain safety and liveness properties of mutual exclusion in such cases, the probabilistic characterization as well as topological analysis of aggregate set in computing space is necessary. This paper proposes a probabilistic algorithm and its topological characterization for mutual exclusion in aggregate set of processes. The analysis of failure model of strictly ordered distributed inclusion–exclusion designs is constructed in the presence of aggregate set. The unbiased probabilistic algorithm is based on two-phased elastic randomization. The algorithm is evaluated through detailed simulation and, the related probabilistic characterization in topological subspace is evaluated. A detailed comparative analysis of the algorithm with respect to other distributed mutual exclusion algorithms is presented.

A Token Based Protocol for Mutual Exclusion in Mobile Ad Hoc Networks

Resource sharing is a major advantage of distributed computing. However, a distributed computing system may have some physical or virtual resource that may be accessible by a single process at a time. The mutual exclusion issue is to ensure that no more than one process at a time is allowed to access some shared resource. The article proposes a token-based mutual exclusion algorithm for the clustered mobile ad hoc networks (MANETs). The mechanism that is adapted to handle token passing at the inter-cluster level is different from that at the intra-cluster level. It makes our algorithm message efficient and thus suitable for MANETs. In the interest of efficiency, we implemented a centralized token passing scheme at the intra-cluster level. The centralized schemes are inherently failure prone. Thus, we have presented an intra- cluster token passing scheme that is able to tolerate a failure. In order to enhance reliability, we applied a distributed token circulation scheme at the inter-cluster level. More importantly, the message complexity of the proposed algorithm is independent of N, which is the total number of nodes in the system. Also, under a heavy load, it turns out to be inversely proportional to n, which is the (average) number of nodes per each cluster. We substantiated our claim with the correctness proof, complexity analysis, and simulation results. In the end, we present a simple approach to make our protocol fault tolerant.

Analysis of Distributed Token Circulation Algorithm with Faulty Random Number Generator

Randomization is a technique to improve efficiency and computability of distributed computing. In this paper, we investigate fault tolerance of distributed computing against faults of random number generators. We introduce an RNG (Random Number Generator)-fault as a new class of faults; a random number generator on an RNG-faulty process outputs the same number deterministically. This paper is the first work that considers faults of randomness in distributed computing. We investigate the role of randomization by observing the impact of RNG-faults on performance of a self-stabilizing token circulation algorithm on unidirectional n-node ring networks. In the analysis, we assume there exist nf (0 ≤ nf ≤ n−1) RNG-faulty nodes and each RNG-faulty node always transfers a token to the next node. Our results are threefold: (1) We derive the upper bound on the expected convergence time in the case of nf = n − 1. (2) Our simulation result shows that the expected convergence time is maximum when nf = n − 1. (3) We derive the expected token circulation time for each nf (0 ≤ nf ≤ n − 1).

Self-Stabilizing Master-Slave Token Circulation Algorithm in Undirected Rings and Unicyclic Graphs of Arbitrary Size and Their Orientations

Token circulation is a fundamental task in the distributed systems. In this paper, we propose a constant space randomized self-stabilizing master-slave token circulation algorithm that works for undirected rings and undirected unicyclic graphs of arbitrary size. We consider the recently introduced and studied master-slave model where a single node is designated to be a master node and other nodes are anonymous slave nodes. The expected stabilization time is O ( n log n ) steps, and the space requirement at each node is 4 bits for any undirected ring (or unicyclic graph) of size n under an unfair distributed daemon; the nodes do not need the knowledge of the size of the ring and hence the protocol is suited for dynamic graphs. The proposed token circulation algorithm is further extended to achieve orientation in the ring and the unicyclic graph. Disregarding the time for stabilization, the orientation can be done in at most O ( n ) steps with 1 bit extra storage at each node for the ring and the unicyclic graph.Â

A token circulation scheme for code assignment and cooperative transmission scheduling in CDMA-based UAV ad hoc networks

Code division multiple access (CDMA) ad hoc networks have been considered a promising multiple-channel networking architecture for connecting tactical platforms in battle fields. In this paper we consider a network of a swarm of unmanned aerial vehicles (UAVs) that are used in a tactical surveillance mission. The UAVs are assumed to have multiuser detection capability and form a CDMA-based ad hoc network. A token circulation scheme is proposed to conduct functions required at the medium access control layer including detection of hidden/lost neighbors, code assignment and schedule-based cooperative transmission scheduling. In the proposed scheme, a token continuously circulates around the network based on the "receive-forward" module. Through circulation of the token, each UAV can detect its hidden and/or lost neighbors in near real-time, assign codes enabling the spatial reuse of code channels without incurring code collision, and schedule data transmissions in a cooperative and distributed manner. In addition, the proposed scheme is able to take advantage of multiuser detection functionality and allows for simultaneous transmissions from multiple transmitters to a same receiver. The performance of the proposed token circulation scheme is evaluated, both analytically and through simulations. It is shown that the latency of the token is at most linearly proportional to the network size, and the average delay of a data packet increases with either the packet generation rate or the network size. The results also show that the proposed token circulation scheme is suitable for large-scale CDMA-based UAV ad hoc networks with even heavy network traffic load.

Universal adaptive self-stabilizing traversal scheme: Random walk and reloading wave

In this paper, we investigate random walk based token circulation in dynamic environments subject to faults. We describe hypotheses on the dynamic environment that allow random walks to meet the important property that the token visits any node infinitely often. The randomness of this scheme allows it to work on any topology, and requires no adaptation after a topological change, which is a desirable property for applications to dynamic systems. For random walks to be a traversal scheme and to solve the concurrency problem, one needs to guarantee that exactly one token circulates in the system. In the presence of transient faults, configurations with multiple tokens or with no token can occur. The meeting property of random walks solves the cases with multiple tokens. The reloading wave mechanism we propose, together with timeouts, allows us to detect and solve cases with no token. This traversal scheme is self-stabilizing, and universal, meaning that it needs no assumption on the system topology. We describe conditions on the dynamicity (with a local detection criterion) under which the algorithm is tolerant to dynamic reconfigurations. We conclude with a study on the time between two visits of the token to a node, which we use to tune the parameters of the reloading wave mechanism according to some system characteristics.

A Cluster-Based Reliable Token Circulation Scheme for Group Communication in MANET

Providing a reliable group communication in a mobile ad hoc network (MANET) is a challenging task. The dynamic nature of this network makes it highly unreliable. Moreover, the future MANETs such as military applications are so large that the disaster recovery scenes would become unmanageable. For better utilization of the system, nodes within the close proximity need to communicate with each other quite often than those which are far apart. To address these issues and to provide a reliable and manageable group communication, this paper proposes a novel token circulation scheme using an adaptive secondary clusterhead-aided clustering algorithm. The token circulation scheme handles token loss and node failures, while the clustering algorithm provides variable diameter clusters, within which group communication is provided. The primary clusterhead is chosen according to the connection degree and mobility of each node. A secondary clusterhead is also set inside each cluster to take charge of part of the duties of the primary clusterhead, such as clustering functionalities, storage of information relating to clustering, token monitoring, etc. Criteria for comparing the algorithms with the existing algorithms include the average time required to complete a round, number of bytes sent per round, number of nodes visited per round, member change frequency in clusters and rate of change of clusterheads. Simulation results show that the proposed token circulation scheme in combination with the clustering algorithm gives better results in comparison with the existing schemes.

Observations on non-silent self-stabilizing algorithms in sensor networks with probabilistically intermittent link failures

A wireless sensor network is a set of nodes, each is equipped with a sensing device and a wireless communication device. Because centralized control is hard to achieve in a large scale sensor network, self- ∗ is a key concept in the design of a wireless sensor network. Self-stabilization is one of the self- ∗ properties, and it is one of the most promising theoretical backgrounds for self-organizing wireless sensor network protocols. Herman [T. Herman, Models of self-stabilization and sensor networks, in: Proceedings of the 5th International Workshop of Distributed Computing, IWDC, 2003, pp. 205–214] proposed Cached Sensornet Transform (CST for short) for design and implementation of self-stabilizing algorithms for sensor networks. It transforms a self-stabilizing algorithm in a high-level computational model to a program for sensor networks. Our contribution in this paper is threefold. We show that there exists a non-silent algorithm that behaves correctly in a high-level computational model but its transformed version by CST does not behave correctly if packets are lost. We show a sufficient condition for original algorithms and networks such that the algorithm transformed by CST behaves correctly. As a case study, we present a token circulation algorithm that behaves correctly by CST and derive the upper bound of its expected convergence time.

Randomization adaptive self-stabilization

We present a scheme to convert self-stabilizing algorithms that use randomization during and following convergence to self-stabilizing algorithms that use randomization only during convergence. We thus reduce the number of random bits from an infinite number to an expected bounded number. The scheme is applicable to the cases in which there exits a local predicate for each node, such that global consistency is implied by the union of the local predicates. We demonstrate our scheme over the token circulation algorithm of Herman (Infor Process Lett 35:63–67, 1990) and the recent constant time Byzantine self-stabilizing clock synchronization algorithm by Ben-Or, Dolev and Hoch (Proceedings of the 27th Annual ACM SIGACT-SIGOPS symposium on principles of distributed computing, (PODC), 2008). The application of our scheme results in the first constant time Byzantine self-stabilizing clock synchronization algorithm that eventually stops using random bits.

Self-stabilization preserving compiler

Self-stabilization is an elegant approach for designing fault tolerant systems. A system is considered self-stabilizing if, starting in any state, it converges to the desired behavior. Self-stabilizing algorithms were designed for solving fundamental distributed tasks, such as leader election, token circulation and communication network protocols. The algorithms were expressed using guarded commands or pseudo-code. The realization of these algorithms requires the existence of a (self-stabilizing) infrastructure such as a self-stabilizing microprocessor and a self-stabilizing operating system for their execution. Moreover, the high-level description of the algorithms needs to be converted into machine language of the microprocessor. In this article, we present our design for a self-stabilization preserving compiler. The compiler we designed and implemented transforms programs written in a language similar to the abstract state machine (ASM). The compiler preserves the stabilization property of the high level program.

Light enabling snap-stabilization of fundamental protocols

In this article, we show that some fundamental self- and snap-stabilizing wave protocols (e.g., token circulation, PIF , etc.) implicitly assume a very light property that we call BreakingIn . We prove that BreakingIn is strictly induced by self- and snap-stabilization. Combined with a transformer, BreakingIn allows to easily turn the non-fault-tolerant versions of those protocols into snap-stabilizing versions. Unlike the previous solutions, the transformed protocols are very efficient and work at least with the same daemon as the initial versions extended to satisfy BreakingIn . Finally, we show how to use an additional property of the transformer to design snap-stabilizing extensions of those fundamental protocols like Mutual Exclusion.

On automatic verification of self-stabilizing population protocols

The population protocol model has emerged as an elegant computation paradigm for describing mobile ad hoc networks, consisting of a number of mobile nodes that interact with each other to carry out a computation. The interactions of nodes are subject to a fairness constraint. One essential property of population protocols is that all nodes must eventually converge to the correct output value (or configuration). In this paper, we aim to automatically verify self-stabilizing population protocols for leader election and token circulation in the Spin model checker. We report our verification results and discuss the issue of modeling strong fairness constraints in Spin.

Self-stabilizing population protocols

This article studies self-stabilization in networks of anonymous, asynchronously interacting nodes where the size of the network is unknown. Constant-space protocols are given for Dijkstra-style round-robin token circulation, leader election in rings, two-hop coloring in degree-bounded graphs, and establishing consistent global orientation in an undirected ring. A protocol to construct a spanning tree in regular graphs using O (log D ) memory is also given, where D is the diameter of the graph. A general method for eliminating nondeterministic transitions from the self-stabilizing implementation of a large family of behaviors is used to simplify the constructions, and general conditions under which protocol composition preserves behavior are used in proving their correctness.

Randomized self-stabilizing and space optimal leader election under arbitrary scheduler on rings

We present a randomized self-stabilizing leader election protocol and a randomized self-stabilizing token circulation protocol under an arbitrary scheduler on anonymous and unidirectional rings of any size. These protocols are space optimal. We also give a formal and complete proof of these protocols. To this end, we develop a complete model for probabilistic self-stabilizing distributed systems which clearly separates the non deterministic behavior of the scheduler from the randomized behavior of the protocol. This framework includes all the necessary tools for proving the self- stabilization of a randomized distributed system: definition of a probabilistic space and definition of the self-stabilization of a randomized protocol. We also propose a new technique of scheduler management through a self-stabilizing protocol composition (cross-over composition). Roughly speaking, we force all computations to have a fairness property under any scheduler, even under an unfair one.

Asynchronous arbiter for micro-threaded chip multiprocessors

This paper presents a scalable and partitionable asynchronous bus arbiter for use with chip multiprocessors and its corresponding pre-layout simulation results using VHDL. The arbiter exploits the advantage of a concurrency control instruction (Brk) provided by the micro-threaded microprocessor model to set the priority processor and move the circulated arbitration token to the most likely processor to issue the create instruction. This mechanism provides latency hiding during token circulation by decoupling the micro-threaded processor from the ring's timing. The arbiter provides a very simple arbitration mechanism and can be used for chip multiprocessor arbitration purposes.

Optimal snap-stabilizing depth-first token circulation in tree networks

We address the depth-first token circulation (DFTC) in tree networks. We first consider oriented trees—every processor knows which of its neighbors leads to a particular processor called the root. On such trees, we propose a state optimal DFTC algorithm. Next, we propose a second algorithm, also for trees, but where no processor knows which of its neighbor leads to the root. This algorithm is also optimal in terms of the number of states per processor. Both algorithms works under any daemon, even unfair. Furthermore, both are snap-stabilizing. A snap-stabilizing protocol guarantees that the system always maintains the desirable behavior. In other words, a snap-stabilizing algorithm is also a self-stabilizing algorithm which stabilizes in 0 steps. Thus, both algorithms are also optimal in terms of the stabilization time. Finally, two approaches of the maximum waiting time to initiate a DFTC are also discussed, whether the tree is oriented or not. In every case but one, we show that the waiting time is asymptotically optimal. In the last case, we conjecture the same result.