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Rendezvous is a vital process for connection establishment and recovery in dynamic spectrum access (DSA) networks. Frequency hopping (FH) is an effective rendezvous method that does not rely on a predetermined control channel. Recently, quorum-based FH approaches have been proposed for enabling asynchronous rendezvous between two or more secondary users (SUs). In this paper, we consider two collocated...
The increased availability of embedded vehicle sensors allows for the detection of road features such as potholes. Despite being a promising approach, current vehicle embedded sensors operate at low frequencies and undersample sensor signals, thus degrading detection accuracy. One emerging solution is to crowdsource such undersampled sensor data from multiple vehicles to increase the detection accuracy...
Taxi-sharing allows occupied taxis to pick up new passengers on the fly, promising to reduce waiting time for taxi riders and increase productivity for drivers. However, if not carefully designed, taxi-sharing may cause more harm than benefit — it becomes harder to strike the balance between driver's profit and passenger's quality of service (e.g. travel time, number of strangers that share a taxi,...
We study the presence of social communities in mobility traces from vehicular fleets. By analyzing publicly available sets of fleet vehicle mobility traces obtained from two real-world deployments — consisting of more than 2000 taxis in Shanghai and Beijing respectively, we confirm the existence of small numbers of distinct social communities in vehicular networks, which is in direct contrast to the...
Real-time abnormal driving behaviors monitoring is a corner stone to improving driving safety. Existing works on driving behaviors monitoring using smartphones only provide a coarsegrained result, i.e. distinguishing abnormal driving behaviors from normal ones. To improve drivers' awareness of their driving habits so as to prevent potential car accidents, we need to consider a finegrained monitoring...
Indoor environment inference is of great importance to mobile and pervasive computing. As high-level metadata of indoor environment, floor maps contain rich information and are widely required in many pervasive systems. However, despite significant research progress, automatic inference of indoor maps has been less studied. In this paper, we present iMap, a smartphone-based opportunistic sensing system...
Wearable smart devices such as smart-glasses, smart-watches and life-logging devices are becoming increasingly popular, and majority of them are being equipped with first-person cameras. Such first-person cameras on smart-glasses or lifeloggers capture photos/videos from user's point of view, allowing them to record and share user's everyday events. However, these wearable devices with first-person...
Without a common control channel in cognitive radio ad hoc networks (CRAHNs), two secondary users have to first hop on a common available channel before setting up their communication link. Existing papers on this blind rendezvous process mainly focus on the sequence design of channel hopping but do not consider the selection of available channels. Their time to rendezvous (TTR) and operation complexity...
The benefit of offloading applications from smart-phones to cloud servers is undermined by the significant energy consumption in data transmission. Most previous approaches attempt to improve the energy efficiency only by choosing a more energy efficient network. However, we find that for computer vision applications, pre-processing the data before offloading can also substantially lower the energy...
In this paper, we propose a novel architecture for next generation cellular networks that enables collaborative forwarding at Layer 2 among adjacent eNBs with the aid of enhanced user equipment (UE) devices, that act voluntarily as packet forwarders. Therefore, legacy UEs are leveraged as active network elements being capable of operating simultaneously over multiple base stations (eNBs). To this...
Recent research has demonstrated the feasibility of full-duplex (FD) communication over the same frequency channel. This capability, facilitated by new self-interference suppression techniques, has great potential to increase the network capacity. However, exploiting FD in the context of a multi-user, multi-channel network is still being debated. This paper focuses on the channel access issue and...
Within the Internet of Things (IoT), Smart Things (STs) promise to permeate all contexts of daily life, offering digital access to their physical functionality. Mobile users then would be able to ubiquitously and spontaneously interact with things they encounter, enabling a wealth of diverse usage scenarios and applications. Currently, however, ST interaction requires a pre-controlled Internet or...
The emergence of the Internet of Things (IoT) introduces a vast ecosystem of new network-enabled objects. Although most current cellular IoT services run over 2G and 3G cellular networks, the Long Term Evolution (LTE) is expected to be one of the main platforms for the emergence of new Machine to Machine (M2M) communication systems. Cellular communication protocols were designed and optimized to handle...
Internet of Things (IoT) commonly identifies the upcoming network society where all connectable devices will be able to communicate with one another. In addition, IoT devices are supposed to be directly connected to the Internet, and many of them are likely to be battery powered. Hence, they are particularly vulnerable to Denial of Service (DoS) attacks specifically aimed at quickly draining battery...
Blockage of communication links due to environmental obstructions and the resulting on/off channel behavior present challenges for providing reliable communication in mobile wireless networks. Traditional reliability techniques such as forward error correction and automatic repeat request (ARQ) are not designed to operate at the timescales typically observed in blockage channels. This work presents...
Downlink Multi-User MIMO (MU-MIMO) enables the simultaneous spatial sharing of the channel by multiple users to achieve a capacity gain over Single-Input Single-Output (SISO) systems. Unfortunately, the overhead required to enable multi-user MIMO is much higher than the overhead required for single-stream systems. Namely, for K users, collection of channel state information requires K transmission...
RPL is an IPv6 routing protocol for low-power and lossy networks (LLNs) designed to meet the requirements of a wide range of LLN applications including smart grid AMIs, industrial and environmental monitoring, and wireless sensor networks. RPL allows bi-directional end-to-end IPv6 communication on resource constrained LLN devices, leading to the concept of the Internet of Things (IoT) with thousands...
We investigate the joint application of compressive sensing and network coding to the problem of energy efficient data gathering in wireless sensor networks. We consider the problem of optimally constructing forwarding trees to carry compressed data to projection nodes; each compressed data refers to a weighted aggregation of measurements from sensors collected at one projection node. Projection nodes...
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