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With the prevailing of mobile phones and online video contents, the demand for mobile online video is increasing. The desire, however, is held down by the high mobile traffic cost. To solve this problem, an off-the-shelf solution is WiFi-Direct (WFD), which is widely available on a majority of mobile devices. There is, however, no systematic study of WFD-based group data transfer and cooperative video...
Device-to-device (D2D) communication is one of the most promising solutions to the dramatic increase of wireless networks traffic load. In D2D communications, mobile nodes can communicate in a semi-autonomous way, with minimal or no control by the base station (BS). In this context, we address the problem of the coexistence of cellular and D2D tiers in the uplink frequencies, where a D2D source is...
To facilitate content delivery to mobile users, we propose a content caching and distribution framework for the heterogeneous OFDM networks, where a library of files available at the macro base station (MBS) can be distributively cached in multiple serving nodes (SNs). SNs are capable of both receiving unstored files from MBS and transmitting files to the associated users. For a given group of file...
This paper investigates multi-user multi-input multi- output cognitive wireless powered communication networks (WPCN), in which a secondary WPCN shares spectrum with a primary wireless information transfer system. A typical WPCN consists of two different phases. In the first downlink phase, a hybrid access point (H-AP) transfers energy to charge users, and then in the subsequent uplink phase, the...
Motivated by the observation that energy harvesting (EH) from radio-frequency (RF) signal is subject to fluctuations, multiple EH-enabled relays are employed to collaboratively enhance data communications in a device-to-device (D2D) network underlying a cellular system. Each relay is equipped with a single antenna and unable to harvest energy and transmit data simultaneously. Thus, the D2D user equipment...
Traffic safety and efficiency are the most important motivations for the rapid development of vehicular ad hoc network (VANET) technology. VANET is considered to provide the unified platform and solutions for the intelligent transportation system (ITS). In this paper, a novel method named spectrum penetration is proposed to improve the throughput of multi-channel MAC for VANET. Meanwhile, it can overcome...
LTE-WLAN Aggregation (LWA) at Radio Access Network (RAN) level offers better performance compared to other WLAN inter-working and offloading mechanisms due to its tighter integration. In rel.~13, 3GPP standardized an LWA architecture which works at the Packet Data Convergence Protocol (PDCP) layer of LTE eNodeB and provides packet-level steering. But this architecture provides sub-optimal...
Performance anomaly is a well-known problem in 802.11 networks. It refers to the case where the aggregated throughput of the multirate network is degraded by slow rate links due to the fair sharing of transmission opportunities. As a result of growing heterogeneity in 802.11 hardware, the coexistence of slow rate and fast rate links are more common and performance anomaly is considered severer. In...
This paper investigates the joint user association (UA) and user scheduling (US) for load balancing in a wireless downlink heterogeneous network by formulating a network-wide utility maximization problem. In order to efficiently solve the problem, we first approximate the original non-convex throughput function to a concave function, and demonstrate that the gap for such approximation approaches zero...
5G Radio Access Networks (RANs) are supposed to increase their capacity by 1000x to handle growing number of connected devices and increasing data rates. The concept of cloud-RAN (CRAN) has been recently proposed to decouple digital units (DUs) and radio units (RUs) of base stations (BSs), and centralize DUs into central offices. CRAN can ease the implementation of advanced radio coordination techniques,...
Software Defined Networking has been adopted to improve data center network efficiency. In SDN, the controllers are responsible for exchanging information with the switches to perform specific operations such as data forwarding. The transmission of control traffic usually uses networks different from data networks. However, building an additional wired network for the control traffic leads to high...
Random linear network coding (RLNC) has been shown to efficiently improve the network performance in terms of reducing transmission delays and increasing the throughput in broadcast and multicast communications. However, it can result in increased storage and computational complexity at the receivers end. In our previous work we considered the broadcast transmission of large file to N receivers. We...
Virtualization of optical access systems is being pursued to speedup service deployment and reduce CAPEX/OPEX. Several passive optical network (PON) specifications have been standardized and the applicability of virtualization to access networks is being considered. We have proposed a programmable optical line terminal (OLT) that performs OLT functions by software processing on general-purpose hardware...
This paper studies a wireless network consisting of multiple transmitter-receiver pairs sharing the same spectrum where interference is regarded as noise. Previously, the throughput region of such a network was characterized for either one time slot or an infinite time horizon. This work aims to close the gap by investigating the throughput region for transmissions over a finite time horizon. We derive...
We study the optimality of almost blank subframes (ABSs) that are used to limit interference by muting macro base stations (BSs) in multi-antenna heterogeneous networks (HetNets). In particular, we formulate a linear program to find the optimal blanking decision that maximizes the average rate of a typical user. A closed-form condition is derived, which depends on the multi-antenna transmission schemes,...
Load-balancing and network optimization in SDN networks require efficient flow splitting during the path computation phase. The way flow splitting is typically implemented in switches is to map the output of an hash function computed on the headers of incoming flows to the content stored in a Ternary Content Addressable Memory (TCAM), a very efficient but scarce resource. Although a large TCAM budget...
In Long Term Evolution (LTE) Networks, several call admission control mechanisms were proposed. They take into account some network constraints such as service diversity and availability of radio resources. However, the shortcomings of the existing mechanisms led us to propose a new approach called Efficient Bandwidth Call Admission Control (EB_CAC). Our proposition considers the quality of service...
In this work, we consider the problem of distributed link scheduling for D2D communications without a centralized controller. Our design goal is to maximize a chosen global objective function. For example, maximizing the long-term proportional fair throughput amongst distributed links can be such a goal. In principle, each link evaluates whether its rate increase by raising its transmit power is sufficient...
We develop a novel opportunistic beamforming scheme referred to as doubly opportunistic beamforming (DOBF), which is doubly selective in both users and beams. The sum-rate performance of the proposed scheme is investigated in less-known finite networks where the number of transmit antennas and the number of active users are finite and of the same order of magnitude in the bursty traffic model. We...
This paper investigates a wireless-powered two-way relay network (WP-TWRN), in which two sources exchange information with the aid of one amplify-and-forward (AF) relay. Contrary to the conventional two-way relay networks, we consider the scenario that the AF relay has no embedded energy supply, and it is equipped with an energy harvesting unit and rechargeable battery. As such, it can accumulate...
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