PENGEMBANGAN DAN IMPLEMENTASI MODEL ALGORITMA COLLISION AWARE RATE ADAPTATION DI SIMULATOR NS-3 UNTUK MENINGKATKAN THROUGHPUT PADA HT-NETWORK

Wireless Local Area Network (WLAN) merupakan jaringan berbasis nirkabel yang telah distandarisasi oleh IEEE dengan kode 802.11. Mulai dari 802.11b/a/g yang mendukung kecepatan transmisi data rate hingga 54 Mbps sampai pada 802.11n dengan kemampuan data rate mencapai 600 Mbps. Dari berbagai variasi data rate tersebut maka diperlukan algoritma rate adaptation yang berfungsi untuk mengontrol penggunaan data rate tersebut. Berdasarkan penelusuran literatur terdapat berbagai macam algoritma rate adaptation. Namun hanya digunakan untuk jaringan legacy rate saja (WLAN 802.11b/a/g) tidak pada jaringan High Throughput (HT-Network) WLAN 802.11n. Indeks data rate pada WLAN 802.11n dipilih berdasarkan ukuran bandwidth kanal 20 atau 40 MHz, long atau short guard interval, dan jumlah spatial stream (1, 2, 3, atau 4). Penelitian yang dilakukan adalah mengembangkan algoritma Collision Aware Rate Adaptation (CARA) menjadi CARA-HT agar dapat diimplementasikan pada WLAN 802.11n. Kemudian dilakukan pengujian pengiriman data menggunakan Aggregate MAC Protocol Data Unit (AMPDU). Pengembangan dan implementasi algoritma CARA-HT dilakukan berdasarkan tahapan-tahapan, sesuai metode penambahan model algoritma baru pada NS-3. Pertama sekali diidentifikasi fungsionalitas dan atribut yang sudah tersedia pada model algoritma CARA dan yang diperlukan oleh algoritma CARA-HT. Kemudian diidentifikasi bagian code algoritma CARA yang dapat digunakan kembali untuk algoritma CARA-HT. Pada hasil pengujian yang telah dilakukan menunjukan bahwa algoritma CARA-HT sudah berfungsi dalam menjalankan adaptasi rate terhadap kondisi collision maupun channel error dan juga berhasil melakukan pengiriman data tanpa atau menggunakan AMPDU. Hasil pengujian juga menunjukkan bahwa adaptasi rate algoritma CARA-HT menghasilkan throughput yang lebih tinggi dibandingkan dengan algoritma CARA.Kata kunci: Rate Adaptation, Collision aware, CARA, CARA-HT, NS-3, WLAN IEEE 802.11n

TANGO: Transparent heterogeneous hardware Architecture deployment for eNergy Gain in Operation

The paper is concerned with the issue of how software systems actually use Heterogeneous Parallel Architectures (HPAs), with the goal of optimizing power consumption on these resources. It argues the need for novel methods and tools to support software developers aiming to optimise power consumption resulting from designing, developing, deploying and running software on HPAs, while maintaining other quality aspects of software to adequate and agreed levels. To do so, a reference architecture to support energy efficiency at application construction, deployment, and operation is discussed, as well as its implementation and evaluation plans.Comment: Part of the Program Transformation for Programmability in Heterogeneous Architectures (PROHA) workshop, Barcelona, Spain, 12th March 2016, 7 pages, LaTeX, 3 PNG figure

A CRC usefulness assessment for adaptation layers in satellite systems

This paper assesses the real usefulness of CRCs in today's satellite network-to-link adaptation layers under the lights of enhanced error control and framing techniques, focusing on the DVB-S and DVB-S2 standards. Indeed, the outer block codes of their FEC schemes (Reed-Solomon and BCH, respectively) can provide very accurate error-detection information to the receiver in addition to their correction capabilities, at virtually no cost. This handy feature could be used to manage on a frame-by-frame basis what CRCs do locally, on the frames' contents, saving the bandwidth and processing load associated with them, and paving the way for enhanced transport of IP over DVB-S2. Mathematical and experimental results clearly show that if FEC has been properly congured for combined error correction and detection, having an uncorrected event after FEC decoding is likely to be an extremely improbable event. Under such conditions, it seems possible and attractive to optimize the way global error-control is done over satellite links by reducing the role of CRCs, or even by removing them from the overall encapsulation process

Generic Model Refactorings

Many modeling languages share some common concepts and principles. For example, Java, MOF, and UML share some aspects of the concepts\ud of classes, methods, attributes, and inheritance. However, model\ud transformations such as refactorings specified for a given language\ud cannot be readily reused for another language because their related\ud metamodels may be structurally different. Our aim is to enable a\ud flexible reuse of model transformations across various metamodels.\ud Thus, in this paper, we present an approach allowing the specification\ud of generic model transformations, in particular refactorings, so\ud that they can be applied to different metamodels. Our approach relies\ud on two mechanisms: (1) an adaptation based mainly on the weaving\ud of aspects; (2) the notion of model typing, an extension of object\ud typing in the model-oriented context. We validated our approach by\ud performing some experiments that consisted of specifying three well\ud known refactorings (Encapsulate Field, Move Method, and Pull Up Method)\ud and applying each of them onto three different metamodels (Java,\ud MOF, and UML)

The DUNE-ALUGrid Module

In this paper we present the new DUNE-ALUGrid module. This module contains a major overhaul of the sources from the ALUgrid library and the binding to the DUNE software framework. The main changes include user defined load balancing, parallel grid construction, and an redesign of the 2d grid which can now also be used for parallel computations. In addition many improvements have been introduced into the code to increase the parallel efficiency and to decrease the memory footprint. The original ALUGrid library is widely used within the DUNE community due to its good parallel performance for problems requiring local adaptivity and dynamic load balancing. Therefore, this new model will benefit a number of DUNE users. In addition we have added features to increase the range of problems for which the grid manager can be used, for example, introducing a 3d tetrahedral grid using a parallel newest vertex bisection algorithm for conforming grid refinement. In this paper we will discuss the new features, extensions to the DUNE interface, and explain for various examples how the code is used in parallel environments.Comment: 25 pages, 11 figure

Model-Based Adaptation of Software Communicating via FIFO Buffers

Software Adaptation is a non-intrusive solution for composing black-box components or services (peers) whose individual functionality is as required for the new system, but that present interface mismatch, which leads to deadlock or other undesirable behaviour when combined. Adaptation techniques aim at automatically generating new components called adapters. All the interactions among peers pass through the adapter, which acts as an orchestrator and makes the involved peers work correctly together by compensating for mismatch. Most of the existing solutions in this field assume that peers interact synchronously using rendezvous communication. However, many application areas rely on asynchronous communication models where peers interact exchanging messages via buffers. Generating adapters in this context becomes a difficult problem because peers may exhibit cyclic behaviour, and their composition often results in infinite systems. In this paper, we present a method for automatically generating adapters in asynchronous environments where peers interact using FIFO buffers.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Near-Capacity Adaptive Analog Fountain Codes for Wireless Channels

In this paper, we propose a capacity-approaching analog fountain code (AFC) for wireless channels. In AFC, the number of generated coded symbols is potentially limitless. In contrast to the conventional binary rateless codes, each coded symbol in AFC is a real-valued symbol, generated as a weighted sum of $d$ randomly selected information bits, where $d$ and the weight coefficients are randomly selected from predefined probability mass functions. The coded symbols are then directly transmitted through wireless channels. We analyze the error probability of AFC and design the weight set to minimize the error probability. Simulation results show that AFC achieves the capacity of the Gaussian channel in a wide range of signal to noise ratio (SNR).Comment: To appear in IEEE Communications Letter

Neutrality: A Necessity for Self-Adaptation

Self-adaptation is used in all main paradigms of evolutionary computation to increase efficiency. We claim that the basis of self-adaptation is the use of neutrality. In the absence of external control neutrality allows a variation of the search distribution without the risk of fitness loss.Comment: 6 pages, 3 figures, LaTe