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Scheduling is a decision-making process that deals with the assignment of resources to tasks over given periods, aiming to optimize one or more objectives. Responsible for efficient distribution of the CPU time among the processes, scheduler has become an essential part of computer systems. While applications run on neighboring cores of a many-core system, they compete with each other for the shared...
Replicating redundant requests has been shown to be an effective mechanism to defend application performance from high capacity variability — the common pitfall in the cloud. While the prior art centers on single-tier systems, it still remains an open question how to design replication strategies for distributed multi-tier systems, where interference from neighboring workloads is entangled with complex...
We study the optimum designs of a wireless ad hoc network that employs a random multiple access protocol and operates in an interference-limited environment. The nodes are assumed to form a homogeneous Poisson point process (PPP). With the random multiple access protocol, each node transmits with a certain probability, the value of which is critical to system performance. A higher transmission probability...
In this paper, we investigate the energy efficiency (EE) and spectral efficiency (SE) tradeoff in multi-cell heterogeneous networks (HetNets). Our objective is to maximize both EE and SE of the network while satisfying the rate requirement of users. We use multi-objective optimization techniques to define the objective function. We propose a three-stage algorithm in this paper. First, we select the...
Wireless sensor networks (WSNs) are dense networks affected by severe interference among many devices. They operate in the unlicensed 2.4 GHz band that is shared by different technologies, such as Bluetooth and WiFi, which add interference at higher transmission power. For this reason, interference is an important factor to avoid for reliable communications. Due to the unpredictable nature of the...
Safety and security in marine environments is an emerging application area of low-power wireless sensor networks. Yet, these environments pose big challenges to network reliability. The IEEE802.15.4-TSCH protocol has been extensively regarded as a reliable low-power wireless sensor network solution. It requires, though, an external scheduling mechanism in place to allocate connections to specific...
Superposed multicarrier transmission is a known method to improve frequency utilization efficiency when several wireless systems share the same spectrum. Obviously, an enhanced spectral efficiency comes at the expense of interference. To suppress the effect of interference, forward error correction (FEC) metric masking can be applied. In FEC, the corresponding log-likelihood (LLR) of the superposed...
This work investigates the problem of channel sensing order in distributed cognitive networks with multiuser, in which the set of active secondary users is randomly changing in each time slot. We model this problem into a non-cooperative game and define a generalized interference metric. The optimization objective is to minimize the generalized interference metric. To cope with this problem, we propose...
In this paper, we study the resource allocation issues related to OFDM-based multiuser cognitive radio cellular networks, where both of primary network and secondary network are investigated to make an all-round evaluation of the network performance, including the Quality of Experience (QoE) of the primary users (PUs) and the minimal rate requirement of the secondary users (SUs). Since the general...
In this paper, we develop and analyze a novel performance metric, called interference efficiency (IE), that shows the number of transmitted bits per unit of interference energy imposed on the primary users (PUs) in an underlay cognitive radio network (CRN). Specifically, we develop a framework to maximize the IE of a CRN with multiple secondary users (SUs) while satisfying target constraints on the...
In this paper, we study the performance of two cross-layer optimized dynamic routing techniques for radio interference mitigation across multiple coexisting wireless body area networks (BANs), based on real-life measurements. At the network layer, the best route is selected according to channel state information from the physical layer, associated with low duty cycle TDMA at the MAC layer. The routing...
While unstructured merge tools try to automatically resolve merge conflicts via textual similarity, semistructured merge tools try to go further by partially exploiting the syntactic structure and semantics of the involved artefacts. Previous studies compare these merge approaches with respect to the number of reported conflicts, showing, for most projects and merge situations, a reduction in favor...
The growing demand on data to enhance the user experience has motivated research toward increasing the efficiency of spectrum utilization by extending cellular technology such as LTE toward unlicensed bands. In order to study the effect of channel access priorities on coexistence of several LAA networks, we consider load based equipment (LBE) based MAC protocol where we use stochastic geometry to...
In this paper, we propose an interference-aware multicast routing scheme for a single-radio Wireless Mesh Networks carrying multiple multicast flows. We focus on multicast routing over WMNs with stationary nodes, such as community wireless networks. We present a new metric that is based on three components: Path Interference Cost (Ip), Broadcast Benefit Factor (BF), and Hop Count (HC). We proposed...
Due to the increase of energy consumption in wireless systems, energy-efficient cellular planning concept has become an important concern in designing cellular networks. In this paper, energy efficiency (EE) and spectral efficiency (SE) analysis for single and multi-cell cellular systems are presented and investigated. The efficiency analysis is studied under the influence of Nakagami-m multi-path...
Friendly jamming is a physical layer security technique that utilizes extra available nodes to jam any eavesdroppers. This paper considers the use of additional available nodes as friendly jammers in order to improve the security performance of a route through a wireless area network. One of the unresolved technical challenges is the combining of security metrics with typical service quality metrics...
Frequency spectrum scarcity has been a strong research motivation. Those researches have focused on developing methodologies to utilize frequency spectrum as much as it could be. Meanwhile, this spectrum utilization and its great revenue should not affect the quality of services being provided by network providers. In most cases, statistics have shown that only quarter of the spectrum is well utilized...
LTE networks are deployed to increase capacity and coverage especially for the indoor and cell-edge mobile users. However, such deployment comes with major challenges, radio resource management and inter-cell interferences. Fractional Frequency Reuse mechanism (FFR) is one of the most effective interference avoidance techniques. In this paper, we evaluate an existing adaptation process that adjusts...
A relay-aided cooperative underlay cognitive radio system with random number of secondary users (SU), and an interference constraint at the primary receiver (PR) is considered. When the primary (PU) is active, those SUs whose interference at the PR is above a threshold will amplify-and-forward PU's signal to enhance the PU's performance, and those SUs below this threshold will proceed with their own...
Effective interference evaluation methods are crucial when making regulatory decisions about whether new wireless technologies should be allowed to operate. Such decisions are highly relevant for both DSA technologies in licensed bands and for technologies coexisting in unlicensed bands. In this paper we demonstrate the benefit of risk-informed interference assessment as an effective method that aids...
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