Zhipeng Yang

Incentive-aware data dissemination in delay-tolerant mobile networks

This work centers on data dissemination in delay-tolerant mobile networks, where data fall into a range of interest types and each node may have one or multiple interests. The goal is to deliver data messages from sources to nodes with corresponding interests. We consider selfish nodes with rational behavior, and propose a credit-based incentive scheme to promote nodal collaboration. The key challenge is to effectively track the value of a message under such a unique network setting with intermittent connectivity and multiple interest types. Given poor end-to-end connections, credits are rewarded to the final deliverer only. Thus the value of a message for an intermediate node highly depends on its probability to deliver the message. Such probability itself is nontrivial to estimate. Moreover, a message is usually desired by multiple mobile users. Therefore, it can be potentially “sold” multiple times to different receivers. On the other hand, while more than one copies can be created during the transmissions of a message, a particular receiver “pays” for the first received copy only. These characteristics together make the development of incentive mechanism a unique, interesting, and challenging problem. In this paper, we present effective schemes to estimate the expected credit reward, and formulate nodal communication as a two-person cooperative game, whose solution is found by using the Nash Theorem. Extensive simulations are carried out based on real-world traces to evaluate the proposed scheme in terms of data delivery rate, delay and overhead. To our best knowledge, this is the first work that incorporates incentive stimulation into data dissemination in delay-tolerant mobile networks with selfish nodes and multiple interest types.

Self-Interest-Driven incentives for ad dissemination in autonomous mobile social networks

In this paper, we propose a Self-Interest-Driven (SID) incentive scheme to stimulate cooperation among selfish nodes for ad dissemination in autonomous mobile social networks. As a key innovation of SID, we introduce “virtual checks” to eliminate the needs of accurate knowledge about whom and how many credits ad provider should pay. A virtual check is included in each ad packet. When an intended receiver receives the packet for the first time from an intermediate node, the former authorizes the latter a digitally signed check, which serves as a proof of successful ad delivery. Multiple copies of a virtual check can be created and signed by different receivers. When a node that owns a signed check meets the ad provider, it requests the provider to cash the check. Both ad packets and signed checks can be traded among mobile nodes. We propose the effective mechanisms to define virtual rewards for ad packets and virtual checks, and formulate the nodal interaction as a two-player cooperative game, whose solution is obtained by the Nash Bargaining Theorem. Extensive simulations are carried out to compare SID with other existing incentive algorithms under real world mobility traces.

Efficient Data Query in Intermittently-Connected Mobile Ad Hoc Social Networks

This work addresses the problem of how to enable efficient data query in a Mobile Ad-hoc SOcial Network (MASON), formed by mobile users who share similar interests and connect with one another by exploiting Bluetooth and/or WiFi connections. The data query in MASONs faces several unique challenges including opportunistic link connectivity, autonomous computing and storage, and unknown or inaccurate data providers. Our goal is to determine an optimal transmission strategy that supports the desired query rate within a delay budget and at the same time minimizes the total communication cost. To this end, we propose a centralized optimization model that offers useful theoretic insights and develop a distributed data query protocol for practical applications. To demonstrate the feasibility and efficiency of the proposed scheme and to gain useful empirical insights, we carry out a testbed experiment by using 25 off-the-shelf Dell Streak tablets for a period of 15 days. Moreover, extensive simulations are carried out to learn the performance trend under various network settings, which are not practical to build and evaluate in laboratories.

Efficient Quality-of-Service (QoS) Support in Mobile Opportunistic Networks

This paper aims to support quality-of-service (QoS) provisioning, particularly the guarantee for end-to-end data delivery delay, in mobile opportunistic networks. The QoS-aware delivery probability (QDP) is introduced to reflect the capability of a node to deliver data to a destination within a given delay budget. Each node maintains a set of QDPs to make autonomous decisions for QoS-aware data transmission. At the same time, a prioritized queue is employed by each mobile node. To support efficient prioritization and redundancy control, the priority is determined by a function of traffic class and data redundancy. The former is predetermined by the corresponding application, whereas the latter is dynamically estimated during data delivery. Two experiments are carried out to demonstrate and evaluate the proposed QoS-aware data delivery scheme. The first experiment involves multiple clusters of static Crossbow sensors that are connected by air and ground mobile nodes with controlled mobility. The second experiment is under a mobile social network setting, where 23 Dell Streak Android tablets are carried by volunteers with arbitrary and diverse mobility patterns over a period of two weeks. Moreover, simulation results are obtained under DieselNet trace and power-law mobility model to study scalability and performance trends. Our experiments and simulations demonstrate that the proposed scheme achieves efficient resource allocation according to the desired delay budget and, thus, supports effective QoS provisioning.

FINDERS: a featherlight information network with delay-endurable RFID support

In this paper, we investigate the use of radio frequency identification (RFID) gear for wireless sensor network construction, aiming to find events of interest and gather aggregate information. In particular, we develop a featherlight information network with delay-endurable RFID support (FINDERS), composed of passive RFID tags that are ultralight, durable, and flexible, without power supply for long-lasting applications. FINDERS faces unprecedented challenges in communication and networking due to its sporadic wireless links, unique asymmetric communication paradigm, intermittent computation capability, and extremely small memory of tags. Several effective techniques are proposed to address these challenges, arriving at an efficient communication protocol for FINDERS. A prototype system is developed, and test-bed experiments are carried out with 38 participants and for 9 days, yielding interesting experimental results that offer valuable insights into RFID-based delay-tolerant networks and provide useful practical guidance for the setup of FINDERS systems.

Featherlight Information Network with Delay-Endurable RFID Support (FINDERS)

This research centers on the Featherlight Information Network with Delay-Endurable RFID Support (FINDERS), composed of passive RFID tags which are ultra light, durable, and flexible, without power supply for long-lasting applications under strict weight constraints and harsh environments. It expands the use of RFID gear for wireless network construction, aiming to find events of interest and gather aggregate information. FINDERS faces unprecedented challenges in communication and networking, due to its sporadic wireless links, unique asymmetric communication paradigm, intermittent computation capability, and extremely small memory of tags. Analytic and simulation data are collected to show the feasibility and efficiency of FINDERS.

Counting in Delay-Tolerant Mobile Networks

This research addresses the problem of counting in Delay Tolerant Networks (DTNs). The goal is to estimate the total number of nodes in the network with short delay time, high accuracy and small storage overhead. DTNs are occasionally connected networks that may suffer from frequent partitions. While counting in conventional (well-connected) networks has been extensively studied, it remains challenging in DTNs, due to the intermittent network connectivity and heterogeneous nodal mobility. In this paper, we propose a novel scheme that exploits effective nodal contact probability to guide the counting process. Extensive simulations based on real mobility traces are carried out to evaluate the performance of our proposed scheme. The results demonstrate that it is highly efficient and outperforms all existing solutions.

Delay-constrained single-copy multi-path data transmission in mobile opportunistic networks

In this work we study the problem of delay-constrained data transmission in mobile opportunistic networks. In contrast to the single-copy single-path and multi-copy multi-path routing schemes that have been discussed in the literature, we aim to determine an optimal single-copy multi-path transmission strategy that satisfies delay requirement and at the same time minimizes communication cost. We first propose a centralized optimal formulation, and then develop a distributed routing algorithm under practical network settings. We implement the proposed algorithm on Dell Streak tablets and carry out an experiment with 25 nodes for a period of two weeks. Moreover, we extract the algorithm codes from our prototype and run simulations based on the Haggle trace to study its performance trends under various network settings.

A New Data Transmission Strategy in Mobile D2D Networks—Deterministic, Greedy, or Planned Opportunistic Routing?

In this paper, we study the problem of delay-constrained data transmission in mobile opportunistic device-to-device networks. In contrast to the deterministic or greedy single-copy single-path (SCSP) and multicopy multipath (MCMP) routing schemes that have been discussed in the literature, we develop a planned opportunistic routing scheme that aims to determine the optimal single-copy multipath (SCMP) transmission strategy that satisfies the delay requirement and, at the same time, minimizes communication cost. We first address the unicast by formulating the optimization problem and developing a distributed routing algorithm under practical network settings. Then, we explore optimal multicast strategies based on the SCMP transmissions. We implement the proposed algorithms on Android tablets and carry out extensive experiments, each with 25 nodes, for a period of two weeks. Moreover, we extract the algorithm codes from our prototype and run simulations based on the Haggle trace to study performance trends under various network settings. The experimental and simulation results show that the proposed protocols achieve significant performance gain in comparison with their counterparts based on SCSP and MCMP transmissions.

Distributed Data Query in Intermittently Connected Passive RFID Networks

This paper focuses on distributed data query in intermittently connected passive RFID networks, which are characterized by extraordinarily limited communication capacity and asynchronous and opportunistic communication links. To address such unique challenges, we propose a distributed data query framework that clusters RFID readers and establishes a 0-1 Knapsack model based on dynamic packet appraisal to enable highly efficient data transmission. We implement a prototype by using Alien RFID gears and carry out experiments that involve 52 volunteers for 14 days to evaluate the proposed data query framework.