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Cognitive Radio is emerged as a means of improving the efficiency of current spectrum by utilizing the available unused spectrum. There are many challenges in the systematization of Cognitive Radio Network and the most obvious is to fulfill the awareness requirement. In a network the nodes are must be able to share the spectral information among them which requires inter node communication channel...
In this paper, we derive fundamental performance limits of underwater (UW) networks via an analysis of the average behavior of random deployments. In particular, we consider an UW network that consists of a Poisson point process of transmitters, each with a receiver at a given distance. The link channel model accounts for path-loss, frequency-dependent absorption, and Rayleigh fading. We evaluate...
Many works have been conducted on cooperation communication in wireless networks for recent years. Two main cooperative modes amplify-and-forward (AF) and decode-and-forward (DF) are proposed in literatures. In this paper, we present a novel cooperation mode selection method, Maximum Throughput Cooperation Mode (MTCM). MTCM selects optimal communication modes, including direct transmission, AF and...
We investigate the network utility maximization (NUM) problem when layered modulation is used at the physical layer of a downlink wireless system. The key idea is to transmit to more than one users with favorable and unfavorable channel qualities at the same time by employing hierarchical constellations. We demonstrate that average throughput of users with unfavorable channel conditions are significantly...
In this paper, we introduce a new approach to schedule interference-free transmissions in wireless networks. We consider a joint scheduling and network coding problem in wireless multicast networks to maximize the throughput. The new approach for scheduling is based on bundling together the interference-free links with similar capacities in the same network realization. For the tested networks, the...
Interference alignment is a new technique recently proposed in physical layer wireless communications research, which purposely align the interference among multiple users thus increase the efficiency of channel use. This paper proposes a new method to enhance throughput of multi-hop wireless networks by utilizing interference alignment at physical layer. At first, it takes a simple network with only...
Most of the link rate adaptation algorithms reduce transmission rate on a failed transmission assuming the cause of the loss to be due to radio channel impairment. However, if this failure is due to collision, then lowering the transmission rate in response is unnecessary. This paper proposes a solution to address this problem by augmenting the rate adaptation algorithm with a loss classification...
Interference is a crucial factor that impacts the overall throughput performance of IEEE 802.11-based wireless networks. As such, understanding interference characteristics is essential towards the optimal management and operation of these networks. In this paper, we use a conducted testbed (that allows us to completely control the signal propagation and received signal strength) to systematically...
In this paper, we investigate the Access Point (AP) deployment problem in Wireless Surveillance Systems (WSSs). Cameras in a WSS could have various demanding upload streaming rates to the AP (usually deemed as a sink or data collector) according to their surveillance requirements, e.g. object detection frequency, video resolution, or the successful ratio of object tracking. Therefore, a suitable AP...
Offering throughput guarantees for cellular wireless networks, carrying real-time traffic, is of interest to both the network operators and the customers. Furthermore, to be able to quantify the soft throughput guarantees for a certain scheduling algorithm without conducting experimental investigations, is valuable for network providers. In this paper, we develop an expression for the approximate...
A great amount of research has devoted to cognitive radio (CR) in recent years in order to improve spectrum efficiency. In decentralized CR networks, the CR users are expected to be capable of dynamically and opportunistically accessing unused spectrums in primary networks. However, since the spectrum of primary networks is comparatively wide, it is not realistic for the CR users to sense the entire...
In this paper, problem of throughput optimization in relay networks where all users transmit their packets on a multiple-access channel is studied by introducing a new Markovian game theoretical solution. Despite the previously reported works, in the proposed model, simultaneously transmitted packets on a multiple-access channel are not always discarded. In this article, the possibility of capturing...
Routing in cognitive networks is a challenging problem due to the primary users' (PU) activities and mobility. Multipath routing is a general solution to improve reliability of connections. Existing multipath routing metrics for traditional wireless networks do not take into account PUs' activities. This work introduces a new routes selection metric for multipath routing in cognitive networks. Routes...
In this paper, we investigate the problem of network coding and media scheduling in wireless multihop networks. Unique characteristics of the wireless media, such as omnidirectional transmissions and destructive interference, as well as having one transceiver per wireless node, imply new code design constraints for wireless networks. Here, we formulate a linear program to solve the joint scheduling...
Network coding has shown the promise of significant throughput improvement. In this paper, we study the throughput of two-hop wireless network coding and explore how the maximum throughput can be achieved under a random medium access scheme. Unlike previous studies, we consider a more practical network where the structure of overhearing status between the intended receivers and the transmitters is...
Cognitive Radio (CR) is a next-generation wireless communication system that exploits underutilized licensed spectrum to optimize the utilization of the overall radio spectrum. A Distributed Cognitive Radio Network (DCRN) is a distributed wireless network established by a number of CR hosts in the absence of fixed network infrastructure. Context awareness and intelligence are key characteristics of...
Relay transmission or cooperative communication is an advanced technique that can improve the performance of data transmission among wireless nodes. However, while the performance (e.g., throughput) of a source node can be improved through cooperation with a number of relays, this improvement comes at the expense of a degraded performance for the relay nodes due to the resources that they dedicate...
The goal of the paper is to enhance the throughput efficiency of wireless adhoc networks. An adhoc network is a collection of wireless mobile hosts forming a temporary network without the aid of any established infrastructure or centralized administration. Each node is considered to be alike here. It is needed to introduce some intelligence to the adhoc networks in order to improve their throughput...
Concurrent Multipath Transmission (CMT) mechanisms have been proposed to improve the transmission performance by means of concurrently transmitting data packets via two or more network interfaces. Based on the wireless cognitive radio, that can dynamically adjust the transmission parameters of the specified device, the required CMT mechanism in the wireless environment differs from that in the wired...
Many studies have shown that Vegas TCP has a better throughput and stability than Reno TCP in homogeneous networks with a single TCP flavor, but performs less well in heterogeneous networks in which two TCP flavors coexist. The progressive behavior of Reno TCP and the conservative behavior of Vegas TCP cause a bias when they are used simultaneously, and thus Vegas TCP fails to obtain a fair share...
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