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This paper investigates the performance dependence of a hybrid free space optical (FSO)/radio frequency (RF) communication system on the data rate, link distance and link availability. In existing hybrid FSO/RF systems with hard switching, an algorithm is used to switch between FSO and RF and vice versa based on the feedback of the channel state information. In particular, two methods based on time...
This paper studies the multi-user performance of multi-cell visible light communication (VLC) systems with coordinated precoding among cells. Practically, separated LED arrays are employed to properly illuminate a large room/office. This configuration enables a multi-cell VLC system, which is analogous to that in mobile cellular networks. In such multi-cell systems supporting multiple users, the received...
We investigate the secrecy connectivity in visible light communication in the presence of randomly located eavesdroppers. We apply spatial point processes to characterize the unknown eavesdropper locations. The closed-form of the secrecy outage probability is derived as a function of the density of eavesdroppers. The analysis is verified by Monte Carlo simulations. Furthermore, we suggest an LED transmitter...
In this paper, we consider the data communication over asymmetric dual hop network having one radio frequency (RF) hop followed by a free space optical (FSO) hop. The communication between a single antenna based RF transmitter and a single aperture based optical receiver is assisted by a decode-and-forward (DF) based dual-input dual-output (DIDO) relay, which possesses RF/FSO capabilities. We have...
With the growing number of connected devices (e.g. smartphones, sensors, actuators and cameras) in 5G, the massive Internet of Thing (IoT) is expected to address a wide range of characteristics and demands, with more radio-frequency (RF) bands to support multiple frequency transmission by 2020. Separate antennas and RF chips may be required for widely separated frequency bands. The development of...
Wireless energy transfer technologies have played an important role in the development of Internet of Things (IoTs). Most of previous studies focus on scheduling mobile chargers efficiently for rechargeable sensor nodes. In this paper, we consider optimizing the deployment for Wireless Charging Stations (WCSs) in urban area. We respect the users detouring cost, when they need move to the candidate...
Fifth-generation mobile and wireless communication systems are actively being studied as a next-generation mobile communication network. People and devices will connect to the Internet via wireless networks in future communication networks, but many challenges must be solved to realize 5G networks. For example, it is difficult to manage connected user devices using centralized control in the control...
The cellular wireless systems are gaining more attention among other connectivity solutions for supporting machine-type communications (MTC). The efficient support of MTC relies on incorporating new features in the communication networks. Ultra-reliable low-latency communications (URLLC) is one of the considered features that is essential for the support of mission-critical applications, such as industrial...
In this paper, we consider the spectrum sensing problem of detecting a primary signal of a macro cell in a cognitive radio network by employing multiple dense small cell base stations. In consideration of the number of cooperative small cells (sample dimension) is comparable to the number of sample (sample size) due to the dense deployment of small cells, sample covariance matrix is no more a good...
In this paper we propose and evaluate an auction-based resource allocation mechanism in a cloud-based radio access network (C-RAN), where the spectrum is managed by several mobile virtual network operators (MVNOs) and the physical resource is owned by the C-RAN operator. Technically, our approach consists of two coupled auctions in a hierarchical way: the lower-level auction between end users and...
Extreme densification of base stations is imminent in the next generation of cellular networks to meet the exponentially increasing demand for mobile data traffic. In such ultra-dense networks (UDNs), the remarkably high inter-cell interference can reduce or even negate the densification gain. On the other hand, directional communications can significantly bring down the interference levels in UDNs...
The effects of human mobility in Device-to-Device (D2D) communication are not well understood, but with the recent proliferation of D2D, communications have become a critical research emphasis. However, very little is understood on how human mobility and D2D communication are interdependent. The unpredictability of human mobility is one of the root causes in properly visualizing and designing an efficient...
Supporting Public Protection and Disaster Relief (PPDR) services are mandatory in modern wireless access networks. The sub-1GHz band is particularly suited to provide PPDR services due to the better propagation characteristics and attendant increase in link budget. In this work, we describe a novel transmit mode under a multi-operator non-orthogonal spectrum sharing framework, which can provide robust...
The efficient deployment of Internet of Things (IoT) over cellular networks, such as Long Term Evolution (LTE) or the next generation 5G, entails several challenges. For massive IoT, reducing the energy consumption on the device side becomes essential. One of the main characteristics of massive IoT is small data transmissions. To improve the support of them, the 3GPP has included two novel optimizations...
In this work we investigate energy efficient packet scheduling problem for the loss tolerant applications. We consider slow fading channel for a point to point connection with no channel state information at the transmitter side (CSIT). In the absence of CSIT, the slow fading channel has an outage probability associated with every transmit power. As a function of data loss tolerance parameters and...
Densely-deployed heterogeneous networks (HetNets) with large number of small cell base stations (SBSs) will constitute one of the main pillars of emerging 5G wireless systems. While such dense deployments of HetNets can help in achieving capacity requirements of 5G networks, they can also result in a significant increase in energy consumption. Since there may not be many associated users in certain...
Wireless Powered Communication Networks (WPCN) is one of the promising approaches to extend the lifetime of the energy-constrained wireless networks such as Wireless Sensor Networks (WSNs). With the advancement in energy harvesting in terms of Wireless Energy Transmission (WET), WPCN overcomes the problem of replacing fixed energy sources such as batteries in difficult access areas of industrial networks...
This paper develops a mathematical model to determine the balance of energy input and data sensing and transmission in a wireless sensing node. Since the node acquires energy through harvesting from an intermittent source, and sensing is also carried out intermittently, the node is modelled with random arrivals of both energy and data. A buffer in the node stores data packets while energy is stored...
IEEE 802.15.4-2015 is the third revision of IEEE 802.15.4 Standard for Low-Rate Wireless Networks. The standard presents Time Slotted Channel Hopping (TSCH) Medium Access Control (MAC) protocol, which provides high reliability and low power consumption to various industrial applications. Despite the effectiveness and the importance of the TSCH protocol, the standard leaves out of its scope in defining...
Machine-to-Machine (M2M) communications are a key enabler of Internet of Things (IoT) applications. Smartphones are a natural choice to serve as gateways (GWs) in mobile M2M communications due to their enhanced connectivity, powered by the ubiquity of mobile networks, and sensing capabilities. However, the use of smartphones as M2M GWs can have an impact on the smartphone usability and introduce undesirable...
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