![]() ![]() The performance studied by means of three metrics:ġ Throughput that measures the amount of raw bytes sent by a source.Ģ Goodput that measures bytes that are sent and success- fully acknowledged.ģ Number of Packets drop. of DL WL Nodes Delayed ACK factor TCP start time Simulation duration The simulation parameters are summarized in Table 1.Ĭhannel bandwidth Frame duration Modulation & Coding Cyclic prefix Contention size The simulation platform is ns-2 (ns2.31) and the WiMAX module is from the National Institute of Standards and Technology (NIST). The investigation was through simulation. International Journal of Scientific & Engineering Research Volume 4, Issue 2, February-2013 2 All subscriber stations are downloading stations (SSs). This section present the system model used in investigation. Finally, the conclusion is present in Section 4. In Sec- tion 3, simulation scenarios are presented and the results are discussed. The system model for the investigation is introduced in Section 2. The rest of the paper is structured as follows. This gives maximum over the air rates of 17.5 Mb/s to 50 Mb/s. Channel sizes defined in the standard are 1.25 MHz to 28 MHz Equipments is currently available for general implement of 3.5, 5.0, 7.0 and 10.0 MHz channel sizes. In order to adapt to different regulations in different countries, and to allocate bandwidth as needed in IEEE 802.16-2004, many different channel sizes have been defined. WiMAX support to the flexible channel sizes. This implies that the TCP throughput and goodput not only depends on the charac- teristics of the data sending channel, but also on the reverse channel used by ACKs. E-mail: have correctly reached to the receiver. Shri Vaishnav Institute of Technologgy and Science, Indore, India. Vishwakarma is currently working as Professor in Kailash Chandra Bandhu is currently pursuing Ph.D in CSE in Bhagwant University, Ajmer, India and Working as Assitant Professor in Acropolis Technical Campus, Indore, India, PH-07312581111. Consequently, at the sender, the timer expires which TCP in- terprets as congestion, the congestion window plummets and the packets are retransmitted, even though these packets may In the presence of an imperfect ACK channel, the ACK clock- ing is disrupted, i.e., packets sent are not duly acknowledged. Normally, there are two ways to indicate the packet loss or congestion: (1) Expiry of retransmission timer (for severe congestion), or (2) receipt of 3 or more duplicate ACKs (for milder conges- tion). The retransmission may aggravate the congestion. In the case of congestion, typically indicated by packet loss, TCP abruptly decreases its congestion window, and re- transmits the lost packets. Under normal network conditions, an ACK is duly received for pack- ets sent, and this helps the sender to increase the data sending rate. Network asymmetry can affect TCP performance, since TCP relies on the timely arrival of acknowledgments (ACKs) to increase its congestion window and data sending rate. Network asymmetry means that network characteristics in one direction do not match with the other direction. WiMAX network increasingly more intelligent and agile communication systems, capable of providing spectrally effi- cient and flexible data rate access. - iMAX is abbreviation `Worldwide Interoperability for Micro-wave Access', is a new wireless OFDM based technology that provides high throughput broadband connection over long distances based on IEEE 802.16. Index Terms- Downlink (DL), Goodput, IEEE 802.16, Medium access control (MAC), OFDM, Packet drop, Subscriber Stations (SSs), Transmission Control Protocol (TCP), Throughput, Uplink (UL) and W orld W ide interoperability for microwave access (W iMAX). The performance of W iMAX network is measured in terms of throughput, goodput and number of packets drop. The performance of W iMAX network is evaluating by varying MAC layer parameter such as channel size, DL:UL ratio and other operating parameter such as downloading traffic (number of downloading wireless nodes). This paper investigates the effect of channel bandwidth in W iMAX network with network asymmetry using TCP New Reno. The W iMAX network asymmetry is largely depends on DL:UL ratio. ![]() VishwakarmaĪbstract - The W orld W ide interoperability for microwave access (WiMAX) technology support to the flexible channel sizes and different countries use different channel it depends on the rule and regulation of countries and their environment. International Journal of Scientific & Engineering Research Volume 4, Issue 2, February-2013 1 The Impact of Channel Bandwidth with Network Asymmetry in WiMAX Network Using TCP New Reno ![]()
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