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In this paper we describe the effects of the radio propagation model on the spatial characteristics of the radio environment. For this study we have conducted a dedicated propagation measurement campaign focusing on the three different frequency bands of 485MHz, 1700 MHz and 2600MHz in order to capture the impact of the used frequency on the radio propagation. The presented results are coming from...
Traffic load balance is among the most crucial issues in heterogeneous cellular networks (HCNs), which can lead to much higher throughput, better user fairness and larger coverage for HCNs. In this paper, we consider the user association problem in HCNs and design a handover scheme for traffic load balancing among macro and femto cells. Three types of handover factors are delicately designed with...
With an increasing demand for monitoring energy consumption at granularity levels down to single household appliances, it is necessary to develop new means to collect sensor measurements in a robust and cost-efficient manner. The smart grid paradigm foresees using wireless links for data transfer, albeit no dedicated spectrum bands have been designated for this purpose. In this paper we study the...
Like physical systems can exist in different phases, the concept of different phases (or states) can be also attributed to other types of systems, such as wireless networks. In this paper we employ the notion of phase diagrams to characterize a wireless network by means of a reduced number of simulation points. By reducing the amount of simulations - compared to fine-grained simulation-based analyses...
Femtocells are a promising approach to provide high data rates through autonomous configuration in indoor environments. However, due to the random and uncontrolled deployment of femtocells within users premises, interference between femtocells themselves and with macrocell base stations is a major issue. In this work, we look into the interference management problem and work towards the development...
A neighborhood discovery (ND), also referred to as a rendezvous (RDV), is a challenging and fundamental phase in opportunistic Cognitive Radio Networks (CRNs) due to changing network topology, the time and location varying spectrum availability and different channel qualities. Simplified solutions, such as, a central controller or common control channel are not feasible in opportunistic CRNs. Therefore,...
We present results from a detailed comparative analysis of spectrum use based on extensive measurement campaigns in two major European metropolitan areas, namely in Paris and London. We focus on frequency bands assigned to cellular systems, and characterize in detail the similarities and differences between operators in terms of how their licensed spectrum is used. In particular, we present extensive...
Recent advances towards opening underutilized spectrum resources for secondary use rely on geolocation databases to determine protection requirements of primary users. This paper studies the achievable accuracy of signal strength estimation for a primary TV network with log-normal propagation models, linear interpolation through Delaunay triangulation, and ordinary kriging as means of including measurement...
In an opportunistic spectrum access (OSA) of cognitive radio wireless networks (CRNs), unlicensed secondary users (cognitive radios, CRs) have only partial knowledge of channel parameters (or other users information) and asymmetric spectral opportunities due to time and space varying channel availabilities. Due to the inherent asymmetry and uncertainty of traffic patterns, CRs can have difficulties...
Harm claim threshold policies will offer more flexibility in radio regulations. By defining bounds on the acceptable field strength over time and space, these policies will introduce quantitative measures to inter-system coexistence questions. How-ever, this requires tangible and sufficient means of proving claims of interference through spectrum measurements. In this paper we study drive test requirements...
In this paper we report the preliminary results from the large-scale spectrum measurement campaign based study to find out correlations between spectrum use and socio-economical data. We use two large spectrum usage datasets that have been collected from metropolitan London and Paris, and correlate the spectrum usage of GSM, UMTS, and 2.4 GHz ISM band against the local population density and location...
An understanding of the underlying spatial structure of user-deployed wireless networks is invaluable for the design and optimization of opportunistic small-cell technologies in emerging multi-tier architectures. IEEE 802.11 Wi-Fi networks provide a real-world example of such a large-scale random network structure. In this paper we report on a high-resolution measurement survey of Wi-Fi deployments...
We present results from an 8-day spectrum measurement campaign in the centre of the London metropolis. We analyze results from one of the densest central areas in our campaign from the perspective of spectrum measurements at a very exposed location at the roof of a high building. We present the main results of this measurement campaign in terms of spectrum utilization, powers received, and evolution...
Due to the changing network topology and the time and location varying spectrum availability in Cognitive Radio Networks (CRNs), there is a need of on-demand searching for a control traffic channel by CR users in order to be able to initiate a communication. This neighborhood discovery phase, also referred to as a rendezvous (RDV) phase, is challenging due to the dynamics of CRNs. There are a number...
Correlations in shadow fading play a key role in the performance of wireless networks. However, despite of this importance, relatively few comprehensive measurement studies have been made on shadow correlations, and the methodology followed in the existing studies is often poorly documented. In this paper we report results from an extensive measurement campaign on shadow correlation in the 485 MHz...
Cognitive MAC protocols are designed to efficiently utilize the scarce spectral resources without affecting the performance characteristics of primary users. The use of spectrum opportunities can often require stochastic approaches due to difficulty in predicting their appearance. Infrastructure based coordinated access techniques are not viable for many applications and spectrum bands, especially...
We present results from the comparison of measurements between dedicated embedded spectrum sensing chip targeting low-cost and low-power applications and a high-end spectrum analyzer. We use different signal types, including actual spectrum usage measured simultaneously with the two devices. We analyze the typical problems such devices suffer from. Finally we also study how to estimate the spectrum...
We report initial results from 48 hour spectrum occupancy measurement campaign that was done in time-correlated fashion in seven different European locations. We give a description of the measurement campaign and provide results from our preliminary analysis of overall duty cycle in the frequency range 110–3000 MHz. The paper particularly focuses on traffic and duty cycle patterns in GSM 900 and GSM...
Recent years have witnessed a number of new and fairly complex MAC schemes for cognitive radios and other reconfigurable networks. These emerging MAC protocols impose increasing demands for flexibility, real-time response and a closer interaction between the MAC- and the physical layers. Different designs for Software Defined Radio (SDR) platforms have been investigated to realize these protocols...
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