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In this paper, we investigate the performance of relay selection in an underlay cognitive radio system in the presence of primary user (PU) interference. In particular, we consider a secondary multi-relay network operating in the amplify-and-forward (AF) mode and only the “best” relay which satisfies an index of merit is selected. The proposed selection strategy takes into consideration the effect...
Incremental opportunistic relaying (IOR) has been proposed to increase the spectral efficiency of the two-phase cooperative transmissions by exploiting limited feedback from the destination node. Specifically, the relaying process is activated only if the source-destination channel is of insufficient quality. In this case, the feedback instructs the best relay to forward the source message to the...
Spectrum sensing is arguably the most important task expected of a cognitive radio. An effective spectrum sensing algorithm enables the cognitive radio to transmit without causing harmful interference to the licensed user. However, in a multi-user environment, the aggregate interference to the sensing node may adversely affect its sensing performance. In this paper, we investigate the performance...
In this paper, the queue dynamics of secondary users (SUs) in a multi-SU and multi-channel cognitive radio network is analyzed to obtain the expressions of quality of service (QoS) metrics. Specially, in the analysis, we take several lower-layer mechanisms and settings into account, including automatic repeat request (ARQ), finite-size buffer, adaptive modulation and coding (AMC) and non-ignorable...
We consider a time slotted cognitive radio (CR) network under Rayleigh fading where multiple secondary users (SUs) contend for spectrum usage over available primary users' channels. In the contention, all SUs use common access probabilities to decide whether they access one of available channels. We focus on the throughput performance of an arbitrary SU. To improve the throughput performance of SUs,...
As more and more wireless communication scenarios, such as Internet of Things and 4G wireless networks, rely on the deployment of wireline networks, the analysis of the heterogeneous wired-wireless networks becomes critical. In this paper, the probability mass function (PMF) of the number of hops in heterogeneous wired and wireless networks is analyzed. The nodes are assumed to be spatially distributed...
One of the today challenges for the mesh networks researches is reliable transmission of multimedia traffic. This traffic demands high quality of service (QoS), to provide which it is suitable to use Mesh Coordinated Channel Access (MCCA) — the novel medium access method described in IEEE 802.11s. According to MCCA, mesh stations (STAs) set up periodic reservations; if all STAs in the network support...
As wireless communications experience tremendous growth, energy consumption is becoming a crucial problem in the wireless industry. Energy saving mechanisms are important for supporting the mobility and extending the battery life of a user equipment, reducing the operation costs of a network operator, enhancing corporate image of operators and vendors alike, and providing a lower total energy consumption...
Vehicular Ad Hoc Networks (VANETs) and their diverse applications experience growing interest in both academic and industry. Different types of traffic packets delivered through vehicle-to-vehicle and vehicle-to-infrastructure communications are intended to improve passenger safety and comfort. In this paper, we propose a multiple priority supported Medium Access Control (MAC) protocol for VANETs...
Cognitive radios have been advanced as a solution to improve spectral efficiency through opportunistic access of the spectrum by unlicensed users. In order to achieve its objective, a cognitive radio is required to conduct periodic spectrum sensing to avoid interfering with the licensed user of the spectrum. In this paper, we examine a multi-channel occupied by a licensed user (primary user) employing...
Hierarchical Mobile IPv6 (HMIPv6) was proposed by Internet Engineering Task Force (IETF) to reduce signalling cost by localising the mobility signalling traffic of Mobile Nodes (MNs). However, certain MNs still generate excessive signalling overhead, due to their ping pong movement at borders of different Mobility Anchor Point (MAP) domains. In this paper, an algorithm is proposed, to effectively...
This paper proposes a mathematical framework to model and analyze the energy consumption of routing protocols in multihop wireless networks such Mobile Ad Hoc Networks (MANETs) or Sensor Networks (WSNs) by taking into account the protocol parameters, the traffic pattern and the network characteristics defined by the medium channel properties, the dynamic topology behavior, the network diameter and...
In trust-based models for MANETs, it is often assumed that the trust value between two nodes decays proportional to the time these nodes are out of transmission range of each other. We present in this paper an analysis of the trust decay rate for some general networking and trust computation models. Our analysis allows for the consideration of the subjective trust values assigned by present and past...
Performance modeling of epidemic routing is challenging because of the unguaranteed end-to-end connectivity and lack of global information in delay-tolerant scenarios. Existing works analyze the scaling law of epidemic protocol based on the assumption that each node has the same infectivity. Whereas, the most recent work indicates that the distribution of infected nodes has spatial-temporal correlation...
We propose a new network model framework, denoted heterogeneous fluid model network, which allows to derive closed formula for the Signal to Interference plus Noise Ratio (SINR) received by a mobile in heterogeneous cellular networks, composed of macro cells and femto cells. Quality of service (QoS) and performance of wireless networks can therefore be analyzed in a simple way. We apply our model...
Probabilistic forwarding methods have been exploited in opportunistic networks to reduce the overhead of epidemic routing. However, most existing methods make all the nodes forward messages with the same probability (i.e., equal scheme), which causes the energy unbalance of nodes. To guarantee the energy balance of nodes and prolong the network lifetime, we design a differentiated scheme, i.e., different...
Route and service discovery in wireless multi-hop networks applies flooding or gossip routing to disseminate and gather information. Since packets may get lost, retransmissions of lost packets are required. In many protocols the retransmission timeout is fixed in the protocol specification. In this paper we demonstrate that optimization of the timeout is required in order to ensure proper functioning...
Vehicular Ad hoc Networks (VANETs) provide vehicle-to-vehicle and vehicle-to-infrastructure communication using Dedicated Short-Range Communications (DSRC). The core objective of VANETs is to provide safety message communication among vehicles. In dense urban traffic, safety message communication encounters severe packet collisions due to excessive number of nodes contending to access the control...
For centralized selection of communication relays, the necessary decision information needs to be collected from the mobile nodes by the access point (centralized decision point). In mobile scenarios, the required information collection and forwarding delays will affect the reliability of the collected information and hence will influence the performance of the relay selection method. This paper analyzes...
It is hard to experiment with test-beds for communication networks: data produced in the network has to be retrieved and analyzed, networks must be reconfigured before and between experiments, data is often little structured (log-files) and analysis methods and tools are generic. Even though many problems of experimentation are the same for all experiments, re-use is sparse and even simple experiments...
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