Extended Equal Service and Differentiated Service Models for Peer-to-Peer File Sharing

Peer-to-Peer (P2P) systems have proved to be the most effective and popular file sharing applications in recent years. Previous studies mainly focus on the equal service and the differentiated service strategies when peers have no initial data before their download. In an upload-constrained P2P file sharing system, we model both the equal service process and the differentiated service process when peers' initial data distribution satisfies some special conditions, and also show how to minimize the time to get the file to any number of peers. The proposed models can reveal the intrinsic relations among the initial data amount, the size of peer set and the minimum last finish time. By using the models, we can also provide arbitrary degree of differentiated service to a certain number of peers. We believe that our analysis process and achieved theoretical results could provide fundamental insights into studies on bandwidth allocation and data scheduling, and can give helpful reference both for improving system performance and building effective incentive mechanism in P2P file sharing systems

ANALISA PERBANDINGAN PERFORMANSI<br /> SKEMA MULTI-LEVEL RED UNTUK DIFFERENTIATED SERVICE DI INTERNET<br /> The Analysis of Multi-level RED Comparative Performance for Differentiated Services In The Internet

ABSTRAKSI: Perkembangan internet saat ini begitu pesat seiring dengan banyaknya user dan aplikasi-aplikasi yang berjalan diatasnya. Jaringan IP tradisional menawarkan user layanan best effort. Dalam layanan best effort, semua paket tidak ada yang dibedakan dan akan diberikan perlakuan forwarding yang sama. Hal ini dapat menyebabkan adanya beban bagi jaringan yang memiliki bandwidth dan buffer space yang terbatas, sehingga dapat menghasilkan kongesti. Dengan adanya mekanisme Quality of Service (QoS), jaringan IP menyediakan suatu diskriminasi pada layanan. Differentiated Service (DiffServ) merupakan salah satu mekanisme yang digunakan untuk meningkatkan Quality of Service (QoS) di jaringan IP. DiffServ adalah arsitektur IP QoS berdasarkan penandaan pada paket yang mengijinkan paket untuk dapat diprioritaskan sesuai dengan keperluan dari user. Multi-level Random Early detection (MRED) kemudian diperkenalkan sebagai suatu skema AQM alternatif yang mendukung implementasi dari DiffServ. Dalam tugas akhir ini diperkenalkan tiga skema MRED, yaitu RED dengan IN/OUT Coupled (RIO-C), RED dengan IN/OUT De-Coupled (RIO-D) dan Weighted RED (WRED). Simulasi menggunakan NS-2 dilakukan untuk membandingkan kinerja masing-masing skema tersebut. Parameter-parameter performansi yang diujikan antara lain packet loss, throughput dan queue delay. Hasil simulasi menunjukkan bahwa kinerja RIO lebih baik dibandingkan WRED dalam hal melindungi paket yang memiliki prioritas yang lebih tinggi pada kondisi load yang dinamis maupun dengan adanya penambahan sumber.Kata Kunci : Kongesti, Differentiated Service, AF-PHB, RIO-C, RIO-D, WREDABSTRACT: Nowadays, the rapid growth of the internet increases as well as the user and the applications running on the internet. Traditional IP networks offer users best effort service. In best effort service, all packets are indistinguishable and are given the same treatment. This has caused burden on the network with limited bandwidth and buffer space, resulting heavy congestion. With the presence of Quality of Service (QoS), IP network provides discriminate services. Differentiated Service (DiffServ) is a mechanism used for increasing the Quality of Service (QoS) on IP network. Diffserv is an IP QoS architecture based on packet marking that allows packets to be prioritized according to users requirements. Multi-level Random Early Detection (MRED) has been introduced afterwards as an alternative scheme which is recommended for supporting the implementation of Diffserv. In this final project would be introduced three schemes of MRED, which are RED with IN/OUT Coupled (RIO-C), RED with IN/OUT De-coupled (RIOD), and Weighted RED (WRED). The performance of these three schemes would be analyzed using ns-2 simulation software. The tested performance metrics are throughput, packet loss and queue delay. The result of simulation shows that the performance of RIO outperform WRED in protecting high priority packet in dynamic load condition or with the increase of sourceKeyword: Congestion, Differentiated Service, AF-PHB, RIO-C, RIO-D, WRED

Analysis of classical retrial queue with differentiated vacation and state dependent arrival rate.

In present paper we have introduced the concept of differentiated vacations in a retrial queueing model with state dependent arrival rates of customers. The arrival rate of customers is different in various states of the server. The vacation types are differentiated by means of their durations as well as the previous state of the server. In type I vacation, server goes just after providing service to at least one customer whereas in type II, it comes after remaining free for some time. In steady state, we have obtained the system size probabilities and other system performance measures. Finally, sensitivity and cost analysis of the proposed model is also performed. The probability generating function technique, parabolic method and MATLAB is used for the purpose

The extent to which grade 7 educators in a full-service school apply differentiated instruction to promote inclusive teaching and learning

A research report submitted to the Faculty of Humanities, University of the Witwatersrand, in partial fulfillment for the degree of Masters of Education by coursework and research report. Johannesburg, March 2016Educators at full-service schools in South Africa are required by policy, to respond to the diversity of learners in the classroom by means of differentiating the learning environment, teaching methods employed and the manner in which the learners are assessed. Within the South African context, three studies relate specifically to differentiated instruction and multi-level teaching: Nel, Kempen and Ruscheinski (2011); de Jager (2013); Walton, Nel, Muller and Lebeloane (2014). The above research was concerned with using differentiated instruction to modify the curriculum of the ‘Learn Not To Burn’ Programme to make it accessible for learners at a special school, challenges with regard to implementing differentiated learning activities within a high school context and investigating responses of educators at a full-service school in the long term, to training they had undergone in multi-level teaching. The topic of this study aims to explore and describe Grade 7 Mathematics and English First Additional Language educators’ understanding, knowledge of and ability to apply differentiated instruction in relation to inclusive teaching and learning within a full-service school. The research was conducted at two, full-service schools in Gauteng, over the course of three weeks. There were six participants in total, including three Grade 7 Mathematics and three Grade 7 English educators. A qualitative research methodology was adopted. Data was collected by means of an initial questionnaire, a preliminary interview, classroom observations, document analysis (analysis of lesson plans and assessment tasks) and post-observation interviews. The patterns which arose from the data analysis were determined by initially summarising the data at an individual level for each participant and then comparing the six participants’ responses with each other in relation to the codes. An analysis of the GPLMS lesson plans indicated that the lesson plans specified core concepts of the curriculum, essential questions relating to the topic were evident, where the topic was divided into specific units to be covered in a particular order. Curricular strategies in relation to content, process and product were stated. However, a key pattern to emerge was that there is an over-reliance on GPLMS lesson plans as opposed to independent planning for differentiation. During classroom observations, the Grade 7 Mathematics and English educators identified big ideas when covering the curriculum, visual supports were evident; the educators varied the format of their instruction and demonstrated sensitivity to the learning needs of individual learners that had been identified during the lessons. While ‘common sense’ inclusive practices were observed, they cannot be described as differentiated instruction per se. The third pattern to emerge was that assessments were not differentiated optimally, as the focus was centred too heavily upon curriculum coverage and ensuring performance on the Annual National Assessment (ANA) exams. Results from this research suggest that at a basic level, some aspects of differentiated instruction are being included in Grade 7 Mathematics and English classrooms in full-service schools in Gauteng. This is not at a sufficient level to facilitate transformation and inclusion. (Key Words: Transformation, inclusion, differentiated instruction, full-service school, GPLMS lesson plans, curricular strategies, assessment tasks)

Throughput Analysis Model for IEEE 802.11e EDCA with Multiple Access Categories

IEEE 802.11e standard has been specified to support differentiated quality of service (QoS), one of the critical issues on the conventional IEEE 802.11 wireless local area networks (WLANs). Enhanced Distributed Channel Access (EDCA) is the fundamental and mandatory contention-based channel access method of IEEE 802.11e, and delivers traffic based on differentiated Access Categories (ACs). A general three dimensional Markov chain model of IEEE 802.11e EDCA for performance analysis is proposed in this paper. The analytical model considers multiple stations with an arbitrary number of different ACs. It also differentiates the contention window (CW) sizes and the arbitration interframe spaces (AIFSs), and considers virtual collision mechanism. Based on the model, the saturation throughput of EDCA is derived, and the accuracy of the proposed model is validated via simulations

A comprehensive analysis of improving the QoS of IMM traffic for high speed wireless campus network

Interactive Multimedia (IMM) applications such as voice and video conferencing are very important in our learning environment. They offer useful services that benefit its users but these services suffers performance degradation from today’s high speed Wireless Local Area Network (WLAN). However, guaranteed Quality of Service (QoS) remains the bottleneck in the network which becomes a great challenge in attempting to improve its performance. This work reviewed many approaches and considers mapping QoS class parameters such as Quality of Service Class Identifier (QCI), Maximum Bit Rate (MBR) and Allocation and Retention Priority (ARP) to the upstream and downstream data flowing in the network as an attempt to improve its performance. Priority is then given to the QoS bearer packets by associating Differentiated Services Code Point (DSCP). A comprehensive analysis of QoS in different protocols in wireless networks has been studied. Open issues and research directions have been addressed with a proposed mechanism to enhance the QoS of the wireless networ