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In this paper, we consider a primary user equipped with a cognitive-enabled radio device and further equipped with an energy harvester with a finite capacity battery. The primary user has highest priority to access a primary channel whereas at the same time tunes the cognitive radio to sense and access to another primary channel if more throughput is needed. At the beginning of each time slot, the...
This paper proposes access policies for the secondary user (SU) of a cognitive radio network (CRN). The SU transmits in the same band as the primary user (PU) where the latter employs Type-II Hybrid-ARQ with incremental redundancy (IR-HARQ). The SU receiver applies interference cancelation to remove a successfully decoded PU message in the subsequent PU transmissions in each HARQ round. The SU transmitter...
We propose a Particle Filter framework to perform online estimation for an unsaturated buffer of the stations in the Machine to Machine (M2M) WiFi network. The dynamical variation of the traffic affects the performance severely in the M2M WiFi network. The exist researches for analyzing the unsaturated condition in the network is based on the steady-state model, whereas this proposed method is devoted...
In this paper a mathematical model of Constrained Priority Countdown Freezing (CPCF) protocol is introduced. In the new model presented, the existing model of simplified CPCF is expanded in order to include the binary exponential backoff (BEB) algorithm. Thus, the behavior of a single CPCF station is modeled using four-dimensional Markov chain. In addition, the probability of the contention loss after...
In heterogeneous LTE networks, an incoming user can either join the femto or the macro base station at the random access stage. We consider a system that has a single macro base station and a number of femtocells in its coverage area. We study the problem of optimally choosing either the femto or the macro station based on the knowledge of the traffic arrival rate and the number of backlogged users...
In this work, we propose and analyze the performance of a scheduler that guarantees to deliver a prescribed number of packets by a given deadline, while minimizing the number of transmission attempts. Channel State Information (CSI) is sent intermittently when considered useful and therefore it can become outdated in some slots. The underwater channel is modeled as a time-varying correlated fading...
Since the seminal work of Grossglauser and Tse [1], the two-hop relay algorithm and its variants have been attractive for mobile ad hoc networks (MANETs) due to their simplicity and efficiency. However, most literature assumed an infinite buffer size for each node, which is obviously not applicable to a realistic MANET. In this paper, we focus on the exact throughput capacity study of two-hop relay...
Multi-hop relaying is an effective technique to combat the negative impacts of channel fading by providing shorter hops between peers in wireless networks. This paper investigates the modeling of a multi-hop Automatic Repeat reQuest (ARQ) system with Decode and Forward (DF) relaying. We propose a three-state Markov model, which is suitable for Rayleigh block fading channels. Analytical throughput...
The real achievable performance of mobile ad hoc networks (MANETs), in particular the performance of such networks under practical constraints, is still largely unknown by now. As a step forward in this direction, this paper focuses on a MANET where a maximum allowed delivery delay is imposed to each packet and examines the impact of such delivery delay constraint on its real achievable performance...
We propose opportunistic spectrum access methods of cognitive femto base station (BS) for time slot level operation after self-configuration and self-optimization processes. When a femto BS shares frequency channels with a macro BS, it performs spectrum sensing and accesses available frequency channels opportunistically. Partially observable Markov decision process (POMDP) and its suboptimal strategy...
A fundamental theoretical problem in opportunistic spectrum access is the following: a single secondary user must choose a channel to sense and access at each time, with the availability of each channel (due to primary user behavior) described by a Markov Chain. The problem of maximizing the expected channel usage can be formulated as a restless multi-armed bandit. We present in this paper an online...
IEEE 802.11 networks have been widely explored since last decade and IEEE802.11g was proposed to increase the data rate of wireless networks up to 54Mbps which ensure backward capability with IEEE802.11b. The main goal of increasing the data rate is to handle high data rate traffic. Many studies have been conducted to analyze the performance of wireless networks using Quality of service constrains...
Service composition is an emerging technology in System of Systems Engineering (SoS Engineering or SoSE), which aims to construct a robust and value-added complex system by outsourcing external component systems. A serviceoriented SoS runs under a dynamic and uncertain environment. To assure the overall Quality of Service (QoS), online reliability time series prediction, which aims to predict the...
The DSRC/WAVE system is standardized to disseminate safety critical information using IEEE 802.11p as a MAC protocol. Studies show that IEEE 802.11p does not address adverse effects of asymmetric radio link and mobility related problems in vehicle to vehicle (V2V) and vehicle to infrastructure (V2I) communications. This paper presents a cross-layer (i.e. MAC and network) algorithm to address these...
In recent years, non-volatile memory devices such as SSD drives have emerged as a viable storage solution due to their increasing capacity and decreasing cost. Due to the unique capability and capacity requirements in large scale HPC (High Performance Computing) storage environment, a hybrid configuration (SSD and HDD) may represent one of the most available and balanced solutions considering the...
In cognitive radio networks with primary users implementing CSMA/CA, such as 802.11 technologies, when all the primary users are in backoff states, the secondary users may detect primary users as inactive and try to access the channel, which will prolong primary users backoff procedure. This phenomenon is called hidden collision. In this paper, we first demonstrate how primary users' performance is...
Wireless or RF energy transfer will be capable of supplying energy to mobile nodes for packet transmission without physical battery changing or replacement. In this paper, we consider the network in which the access point can transfer wireless energy to the nodes and the nodes use that energy to transmit packets. The nodes can send requests (i.e., bids) to the access point for transferring wireless...
Developing an efficient spectrum access policy enables cognitive radios to dramatically increase spectrum utilization while assuring predetermined quality of service levels for the primary users. In this paper, modeling, performance analysis, and optimization of a distributed secondary network with random sensing order policy are studied. Specifically, the secondary users create a random order of...
In Vehicular Ad Hoc Networks (VANETs), vehicles along highways can be grouped into clusters. The design of VANET clusters (i.e., size and geographical span) depends on the packet collision in MAC layer, the wireless channel conditions in PHY layer, and the mobility of the vehicles. Existing works investigated these effects separately. In this paper, we present a comprehensive analysis that combines...
An increasing number of streaming applications need packets to be strictly in-order at the receiver. This paper provides a framework for analyzing in-order packet delivery in such applications. We consider the problem of multicasting an ordered stream of packets to two users over independent erasure channels with instantaneous feedback to the source. Depending upon the channel erasures, a packet which...
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