@inproceedings{wang_li_wang_song_2016, title={A locality-based mobile caching policy for D2D-based content sharing network}, DOI={10.1109/glocom.2016.7841510}, abstractNote={As the explosion of Internet traffic is quickly leading to overloaded cellular network, device-to-device (D2D)-based content sharing is proposed as a method to offload mobile data traffic. The performance of D2D-based content sharing is dramatically affected by the success rate of content fetching from nearby devices and quality of content transmission, which is determined by the geographic distribution of mobile devices, the number of devices having contents in their caches, and the condition of D2D links. Hence, a key problem is how to cache various contents in the limited storage of mobile devices for improving the success rate of content fetching. In this paper, we aim to design a caching policy by considering the joint impact of locality of real-world mobile data traffic and device contact pattern to improve the success rate of content fetching. To do this, we first study the characteristics of network traffic and device contact pattern by analyzing traces from realistic networks. Then, we design a locality-based caching policy and derive the content caching probability and hit ratio through mathematical analysis. Through numerical evaluation and trace-driven simulations, we not only quantify how content popularity, content active lifetime, content size, content bit rate, device storage, transmission rate, and closeness centrality affect the content hit ratio, but also provide comparison on hit ratio and storage cost in different caching policy, which is a strong evidence that the joint impacts from characteristics of content and device are the necessary consideration when to design a caching policy.}, booktitle={2016 ieee global communications conference (globecom)}, author={Wang, Y. L. and Li, Y. J. and Wang, Wenye and Song, M.}, year={2016} }
 @article{sun_wang_li_2016, title={The Impact of Network Size and Mobility on Information Delivery in Cognitive Radio Networks}, volume={15}, ISSN={["1558-0660"]}, DOI={10.1109/tmc.2015.2398420}, abstractNote={There have been extensive works on the design of opportunistic spectrum access and routing schemes to improve spectrum efficiency in cognitive radio networks (CRNs), which becomes an integral component in the future communication regime. Nonetheless, the potentials of CRNs in boosting network performance yet remain to be explored to reach the full benefits of such a phenomenal technique. In this paper, we study the end-to-end latency in CRNs in order to find the sufficient and necessary conditions for real-time applications in finite networks and large-scale deployments. We first provide a general mobility framework which captures most characteristics of the existing mobility models and takes spatial heterogeneity into account. Under this general mobility framework, secondary users are mobile with an mobility radius a, which indicates how far a mobile node can reach in spatial domain. We find that there exists a cutoff point on a, below which the latency has a heavy tail and above which the tail of the latency is bounded by some Gamma distributions. As the network grows large, the latency is asymptotically scalable (linear) with respect to the dissemination distance (e.g., the number of hops or euclidean distance). An interesting observation is that although the density of primary users adversely impacts the expected latency, it makes no influence on the dichotomy of the latency tail in finite networks and the linearity of latency in large networks. Our results encourage CRN deployment for real-time and large applications, when the mobility radius of secondary users is large enough.}, number={1}, journal={IEEE TRANSACTIONS ON MOBILE COMPUTING}, author={Sun, Lei and Wang, Wenye and Li, Yujin}, year={2016}, month={Jan}, pages={217–231} }
 @article{li_wang_2014, title={Message Dissemination in Intermittently Connected D2D Communication Networks}, volume={13}, ISSN={["1558-2248"]}, DOI={10.1109/twc.2014.2317703}, abstractNote={Device-to-device (D2D) communications enable direct communications and information distribution among closely located devices in wireless networks. Many applications of D2D communications require message dissemination to a group of mobile users at certain locations. The challenges of message dissemination come from highly dynamic network environments due to movements of devices. Existing studies on message dissemination have focused on information propagation speed and latency, but the size of the area affected by message dissemination at time t is also critical to D2D communication applications that heavily depend on message dissemination among users in a geographic region. In this paper, we study the fundamental issues in D2D communications: how far the message dissemination can reach by time t (referred as dissemination distance) and how long the dissemination takes to inform nodes located at distanced (referred to as hitting time), especially in dynamic, intermittently connected networks. We first derive analytic bounds of dissemination distance and hitting time under different dissemination mechanisms, providing the spatial and temporal limits of message dissemination. Analytic results are further validated by simulation results of several corresponding dissemination algorithms. Finally, two application scenarios are provided to illustrate how our results serve as guidelines to choose or design appropriate dissemination methods for different D2D communication applications.}, number={7}, journal={IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS}, author={Li, Yujin and Wang, Wenye}, year={2014}, month={Jul}, pages={3978–3990} }
 @article{li_zhao_wang_2013, title={Internode Mobility Correlation for Group Detection and Analysis in VANETs}, volume={62}, ISSN={["1939-9359"]}, DOI={10.1109/tvt.2013.2264689}, abstractNote={Recent studies on mobility-assisted schemes for routing and topology control and on mobility-induced link dynamics have presented significant findings on the properties of a pair of nodes (e.g., the intermeeting time and link life time) or a group of nodes (e.g., network connectivity and partitions). In contrast to the study on the properties of a set of nodes rather than individuals, many works share a common ground with respect to node mobility, i.e., independent mobility in multihop wireless networks. Nonetheless, in vehicular ad hoc networks (VANETs), mobile devices installed on vehicles or held by humans are not isolated; however, they are dependent on each other. For example, the speed of a vehicle is influenced by its close-by vehicles, and vehicles on the same road move at similar speeds. Therefore, the gap between our understanding of the impact of independent mobility and our interest in the properties of correlated mobility in VANETs, along with the real systems altogether, declare an interesting question. How can we measure the internode mobility correlation, such as to uncover the node groups and network components, and explore their impact on link dynamics and network connectivity? Bearing this question in mind, we first examine several traces and find that node mobility exhibits spatial locality and temporal locality correlations, which are closely related to node grouping. To study the properties of these groups on the fly, we introduce a new metric, i.e., dual-locality ratio (DLR), which quantifies mobility correlation of nodes. In light of taking spatial and temporal locality dimensions into account, the DLR can be used to effectively identify stable user groups, which in turn can be used for network performance enhancement.}, number={9}, journal={IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY}, author={Li, Yujin and Zhao, Ming and Wang, Wenye}, year={2013}, month={Nov}, pages={4590–4601} }
 @inproceedings{li_wang_2012, title={Geo-dissemination in vehicular ad hoc networks}, DOI={10.1109/icc.2012.6364456}, abstractNote={Vehicular Adhoc Networks (VANETs) aim to improve road safety and convenience through vehicle-to-vehicle and vehicle-to-roadside communications. Traffic information and accident warnings are often disseminated to vehicles in certain areas where driving could be affected by hazardous situations. Such message dissemination with destinations confined in specific geographic regions is referred to as Geo-Dissemination. In this paper, we analyze how far a geo-dissemination can possibly reach over a period of time t (denoted as dissemination distance D(t)), and what is the latency for a message to reach locations that are d distance far from the source (denoted as the stopping time τ). Simulations results of two dissemination methods (stateless opportunistic forwarding and GPS-based message broadcasting) are compared with our analytic results.}, booktitle={2012 ieee international conference on communications (icc)}, author={Li, Y. J. and Wang, Wenye}, year={2012} }
 @inproceedings{li_wang_duel-hallen_2012, place={Piscataway, NJ, USA}, title={The latency of gaining alpha-reliability for message dissemination in vehicle-to-vehicle networks}, url={http://dx.doi.org/10.1109/GLOCOM.2012.6504004}, DOI={10.1109/glocom.2012.6504004}, abstractNote={In many Vehicular Ad-hoc Network applications, such as hazard warning and traffic coordination, the message dissemination in unreliable and highly mobile network environment is a key challenge. In order to understand the relationship between dissemination latency and reliability, we analyze the latency of gaining α-reliability that a node correctly receives a message with probability larger than α (0 < α< 1). Under a 1-Dimensional (1-D) network scenario with unreliable channel and constrained vehicle mobility, we derive the minimum latency of gaining almost sure α-reliability, denoted as tmin(α). Besides dissemination reliability requirement α, tmin(α) also depends on node's original distance from the source, node mobility, channel reliability, and traffic flow. Numerical analysis discloses several interesting insights that 1) tmin(α) is dominated by the first attempt to send the message to a destination, 2) node mobility has little impact on tmin(α) in emergency information dissemination, and 3) transmission range and node density greatly affect dissemination latency and reliability.}, booktitle={2012 ieee global communications conference (globecom)}, author={Li, Y. J. and Wang, Wenye and Duel-Hallen, A.}, year={2012}, pages={5550–5555} }
 @inproceedings{li_zhao_wang_2011, title={Intermittently connected vehicle-to-vehicle networks: Detection and analysis}, DOI={10.1109/glocom.2011.6134395}, abstractNote={Vehicular Adhoc Networks (VANETs) are dedicated to improve the safety and efficiency of transportation systems through vehicle to vehicle or vehicle to road side communications. VANETs exhibit dynamic topology and intermittent connectivity due to high vehicle mobility. These distinguished features declare a challenging question: how to detect on the fly vehicular networks such that we can explore mobility-assisted message dissemination and topology control in VANETs. As being closely related to network dynamics, vehicle mobility could be explored to uncover network structure. In this paper, we have observed that mobility of vehicle, rather than being random, shows \emph{temporal locality} (i.e., frequently visiting several communities like home and office), and \emph{spatial locality} (i.e., velocity constrained by road layout and nearby vehicles). We first examine temporal locality using a campus trace, then measure temporal locality similarity between two vehicles based on the relative entropy of their location preferences. By further incorporating spatial locality similarity, we introduce a new metric, namely \emph{dual locality ratio} (DLR), which represents the mobility correlation of vehicles. Simulation results show that DLR can effectively identify dynamic vehicular network structures. We also demonstrate applications of DLR for improving performances of data forwarding and clustering in vehicle-to-vehicle networks.}, booktitle={2011 ieee global telecommunications conference (globecom 2011)}, author={Li, Y. J. and Zhao, M. and Wang, Wenye}, year={2011} }
 @article{li_wang, title={Modeling and analysis of single-hop mobile cloudlet}, journal={Advances in Mobile Cloud Computing Systems}, author={Li, Y. J. and Wang, W. Y.}, pages={231–256} }