ELAAH MODEL-MODEL PROPAGASI RADIO UNTUK SISTEM RADIO DUA-ARAH PITA VHF-UHF PADA AREA PERTAMBANGAN TERBUKA DAERAH TROPIS

Prasarana telekomunikasi diperlukan untuk menunjang operasional pertambangan dengan area sangat luas. Sistem komunikasi radio dua-arah yang paling layak dipertimbangkan untuk melayani area tersebut diatas. Agar sistem radio bisa menghasilkan performa yang optimal perlu adanya perencanaan jaringan radio, yang melibatkan penggunaan model propagasi radio. Permasalahan dari penelitian ini adalah cara menentukan model propagasi yang sesuai untuk sistem radio dua-arah pada pita very high frequency dan ultra high frequency (VHF-UHF) pada area pertambangan terbuka dengan kondisi lahan tidak beraturan. Tujuan dari penelitian ini adalah investigasi sejumlah model propagasi radio yang sesuai untuk sistem komunikasi radio dua-arah pada pita VHF-UHF di area pertambangan terbuka dengan kondisi geografis yang tak beraturan untuk daerah tropis, dengan studi kasus di wilayah pulau Kalimantan, Indonesia. Metode yang digunakan adalah penentuan obyek riset, penentuan parameter jaringan radio, investigasi model propagasi, studi literature, analisis dan evaluasi model, klasifikasi model. Hasil analisis menunjukkan Standard Propagation Model memiliki performa terbaik untuk prediksi sistem radio area pertambangan. Namun, metode ini memiliki kekurangan yang memerlukan kalibrasi cukup kompleks

The impact of the access point power model on the energy-efficient management of infrastructured wireless LANs

The reduction of the energy footprint of large and mid-sized IEEE 802.11 access networks is gaining momentum. When operating at the network management level, the availability of an accurate power model of the APs becomes of paramount importance, because different detail levels have a non-negligible impact on the performance of the optimisation algorithms. The literature is plentiful of AP power models, and choosing the right one is not an easy task. In this paper we report the outcome of a thorough study on the impact that various inflections of the AP power model have when minimising the energy consumption of the infrastructure side of an enterprise wireless LAN. Our study, performed on several network scenarios and for various device energy profiles, reveals that simple one- and two-component models can provide excellent results in practically all cases. Conversely, employing accurate and detailed power models rarely offers substantial advantages in terms of power reduction, but, on the other hand, makes the solving algorithms much slower to execute

Optimal Access Point Power Management for Green IEEE 802.11 Networks

In this paper, we present an approach and an algorithm aimed at minimising the energy consumption of enterprise Wireless Local Area Networks (WLANs) during periods of low user activity. We act on two network management aspects: powering off some Access Points (APs), and choosing the level of transmission power of each AP. An efficient technique to allocate the user terminals to the various APs is the key to achieving this goal. The approach has been formulated as an integer programming problem with nonlinear constraints, which comes from a general but accurate characterisation of the WLAN. This general problem formulation has two implications: the formulation is widely applicable, but the nonlinearity makes it NP-hard. To solve this problem to optimality, we devised an exact algorithm based on a customised version of Benders’ decomposition method. The computational results proved the ability to obtain remarkable power savings. In addition, the good performance of our algorithm in terms of solving times paves the way for its future deployment in real WLANs.publishedVersio

Network Planning for IEEE 802.16j Relay Networks

In this chapter, a problem formulation for determining the optimal node location for base stations (BSs) and relay stations (RSs) in relay-based 802.16 networks is developed. A number of techniques are proposed to solve the resulting integer programming (IP) problem—these are compared in terms of the time taken to find a solution and the quality of the solution obtained. Finally, there is some analysis of the impact of the ratio of BS/RS costs on the solutions obtained. Three techniques are studied to solve the IP problem: (1) a standard branch and bound mechanism, (2) an approach in which state space reduction techniques are applied in advance of the branch and bound algorithm, and (3) a clustering approach in which the problem is divided into a number of subproblems which are solved separately, followed by a final overall optimization step. These different approaches were used to solve the problem. The results show that the more basic approach can be used to solve problems for small metropolitan areas; the state space reduction technique reduces the time taken to find a solution by about 50 percent. Finally, the clustering approach can be used to find solutions of approximately equivalent quality in about 30 percent of the time required in the first case. After scalability tests were performed, some rudimentary experiments were performed in which the ratio of BS/RS cost was varied. The initial results show that for the scenarios studied, reducing the RS costs results in more RSs in the solution, while also decreasing the power required to communicate from the mobile device to its closest infrastructure node (BS or RS)

A Tale of Ten Cities: Characterizing Signatures of Mobile Traffic in Urban Areas

International audienceUrban landscapes present a variety of socio-topological environments that are associated to diverse human activities. As the latter affect the way individuals connect with each other, a bound exists between the urban tissue and the mobile communication demand. In this paper, we investigate the heterogeneous patterns emerging in the mobile communication activity recorded within metropolitan regions. To that end, we introduce an original technique to identify classes of mobile traffic signatures that are distinctive of different urban fabrics. Our proposed technique outperforms previous approaches when confronted to ground-truth information, and allows characterizing the mobile demand in greater detail than that attained in the literature to date. We apply our technique to extensive real-world data collected by major mobile operators in ten cities. Results unveil the diversity of baseline communication activities across countries, but also evidence the existence of a number of mobile traffic signatures that are common to all studied areas and specific to particular land uses