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Inter-cell interference is a major issue in current wireless cellular systems, in particular with the development of femto-cells. Efficient macro-femto inter-cell interference coordination (ICIC) is crucial and should be performed with minimum communication between macro and femto base stations. We propose an ICIC approach, in which each femto base station informs a server about its position, obtains...
In this paper1, we propose to analyze and combine two of the main enabling features of cognitive radio: location awareness and spectrum sensing with taking into account one of the most challenging hardware limitation that cognitive radio may suffer from: signal acquisition at a Nyquist rate. During the problem formulation and when analyzing more deeply the equations related to each question apart,...
Relay aided cellular network promises numbers of attractive performances such as cell-edge throughput improvement, fairness enhancement, higher throughput and etc, which is considered in Long-Term-Evolution-Advanced (LTE-A) standard. However, the promised advantages can only be achieved under proper co-channel interference control such as employing Fractional Frequency Reuse (FFR). To overcome the...
For WLAN systems in which relaying is used to improve throughput performance, node mobility and information collection delays can have a significant impact on the performance of a relay selection scheme. This paper analyzes this influence on the decision process using a previously developed Markov Chain model. The evaluation is done for a realistic indoor scenario that is based on ray-tracing enriched...
Wireless sensor networks (WSNs), due to the limited resources of the nodes, are highly vulnerable to attacks at all network layers; however, the so-called “wormhole attack” is particularly challenging because it resists defensive measures exclusively based on cryptographic protocols. In this paper we propose two wormhole detection procedures for WSNs, based on concepts employed in a kind of range-free...
Location information can reduce the complexity of vertical handover decision algorithms by means of reducing the subset of candidate networks. In this sense, GPS is commonly suggested to obtain nodes position. However, energy consumption of GPS systems can be reduced if nodes are assisted by localization algorithms, where only a smaller subset of nodes provide GPS location information. In this paper...
Energy consumption of mobile and wireless networks and devices is significant, indirectly increasing greenhouse gas emissions and energy costs for operators. Cognitive radio (CR) solutions can save energy for such networks and devices; moreover, the energy consumption of CR technologies themselves have to be considered. This paper discusses ways in which standardization efforts can assist the use...
This paper presents a modular decision flow for the selection of radio access technique (RAT), carrier frequency, and bandwidth for opportunistic networks that are operator governed temporary extensions of mobile communication network infrastructures. In this study the emphasis is placed on finding an optimal (band, RAT) combination for each opportunistic network link so that adequate bit rate can...
This paper analyzes the possibility to introduce a WiFi type of secondary network containing multiple secondary access points (SAPs) in TV bands. In particular, the analysis investigates the limitations of TV whitespace (TVWS) usage imposed by the aggregate interference of the secondary users towards the primary and secondary system, assuming different levels of penetration of the TVWS-operating technology...
In this paper, we propose a novel contention-aware channel selection algorithm that focuses on throughput and energy efficiency improvement in Cognitive Radio Ad-Hoc Networks (CRAHNs). Specifically, we study the operation and performance of a Secondary Network (SN) in a scenario where other non-cooperating CRAHNs are also using the primary resources. We prove that a channel categorization of the idle...
This paper elaborates on a prototype spectrum management framework, for dynamic exploitation of underused radio spectrum, such as TV White Spaces (TVWS), QoS provisioning and policy management, under the real time secondary spectrum market policy. The proposed framework is applied in a centralised Cognitive Radio (CR) network architecture, where the exploitation of the available TVWS, as well as the...
The Long Term Evolution (LTE) system, and especially its current release, LTE-Advanced, is considered as the next step in mobile broadband networks. Two of the main challenges faced by the LTE system are: i) to offer ubiquitous and highly reliable wireless services, and ii) to efficiently utilize the assigned spectrum portion. A promising approach towards this direction is to allow the establishment...
In this paper we present a hybrid discrete Particle Swarm Optimization (PSO) algorithm for the Mobile Network Deployment Problem (MNDP). First, we fully describe the MNDP, including a term for taking into account the Electromagnetic field produced by new locations of BTSs. We also describe the proposed PSO algorithm and some variations incorporated in order to cope with discrete search spaces, such...
In this paper, we propose the use of an expert system in order to improve a load balancing mechanism in a hybrid multihop network. The use of Fuzzy Logic is particularly appropriate in this type of networks because of the uncertainty associated with the movement of mobile nodes. In our proposal, mobile nodes select routes to the Internet based on a knowledge-based system. The expert system uses a...
The feedback load is an important parameter with a large impact in Orthogonal Frequency Division Multiple Access (OFDMA) techniques, as a feedback over each one of the subcarriers will induce a non-acceptable signalling load in the system, so that some optimization and feedback reduction strategies are required to meet practical systems demands. The decision over the best strategy for feedback optimization...
In this paper, we consider the energy efficiency (EE) of a single-link system, requiring feedback for reliable transmission. A quantized value of the signal-to-noise ratio is sent back to select the scheme that achieves maximum EE. Besides the energy consumption at the transmitter, we account for the energy consumed at the receiver to feedback the channel state information to the transmitter, which...
This paper presents a novel heuristic multi-criteria tool capable of generating open-access wireless network deployments by exploiting the existing broadband infrastructure. Specifically, an external user dynamically selects, by virtue of our proposed scheme, a certain network layout depending on the target percentage of non-covered users and cost of the deployment. Network layouts differently balancing...
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