Resequencing Analysis of Stop-and-Wait ARQ for Parallel Multi-channel Communications(2009)

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Abstract:

Under the assumption that all channels have the same transmission rate but possibly different time-invariant error rates, we derive the probability generating function of the resequencing buffer occupancy and the probability mass function of the resequencing delay. Then, by assuming the Gilbert–Elliott model for each channel, we extend our analysis to time-varying channels.

Through examples, we compute the probability mass functions of the resequencing buffer occupancy and the resequencing delay for time-invariant channels. We analyze trends in the mean resequencing buffer occupancy and the mean resequencing delay as functions of system parameters.

Algorithm / Technique used:

Gilbert–Elliott Model.

Algorithm Description:

Very simple mode: channel states

1. Good state: signal above “threshold”, BER is virtually Zero

2. Poor state: “signal outage”, BER s ½, reciver falls out of sync, etc.

Markov model approach.

1. Memory less transistions.

2. Exponential distribution sojoum time.

Existing System:

An analytical approach for analyzing the mean % packet delay and mean queue length at the transmitting terminal in % wireless packet networks using the selective repeat (SR) automatic % repeat request (ARQ) scheme to control the errors introduced by the % non-stationary transmission channel. Each transmitting terminal is % modeled as a discrete time queue with an infinite buffer. The% non-stationary transmission channel is modeled as a two-state Markov % chain. Comparisons of numerical predictions and simulation results are % presented to highlight the accuracy of the proposed analytical approach

In a wireless communication system, however, the transmission condition of a wireless channel changes over time, and consequently, the channel is often severely affected by time-varying lossesAn ARQ system corrects erroneously received packets through retransmission of packets. The idea of using three classical ARQ schemes (or protocols) have been developed:stop-and-wait ,go-back-N and selective-repeat .In SW-ARQ, the transmitter sends a packet to the receiver and waits for its acknowledgment. Based on error-detection results, the receiver generates either a negative acknowledgment or a positive acknowledgment for each received packet and sends it over a feedback channel. If an ACK is received, the transmitter sends out a next packet; otherwise, if an NACK is received, retransmission of the same packet will be scheduled immediately, and this process continues until the packet is positively acknowledged.In GBN, the transmitter sends packets to the receiver continuously and receives acknowledgments as well. When a NACK is received, the transmitter retransmits the negatively acknowledged packet immediately and all already-transmitted packets (positively and negatively acknowledged) following it.

Proposed System:

We consider a multi-channel data communication system in which the stop-and-wait automatic-repeat request protocol for parallel channels with an in-sequence delivery guarantee (MSW-ARQ-inS) is used for error control. We evaluate the resequencing delay and the resequencing buffer occupancy, respectively. We expect that the modeling technique and analytical approach used in this project can be applied to the performance evaluation of other ARQ protocols (e.g., the selective-repeat ARQ) over multiple time-varying channels. In SR-ARQ, the transmitter sends packets continuously until a NACK arrives at the transmitter, in which case the transmitter retransmits the negatively acknowledged packet without resending the transmitted packets following it. To preserve the original arriving order of packets at the receiver, the system has a buffer, referred to as the resequencing buffer, to store the correctly received packets that have not been released. These ARQ protocols for single-channel communications have been extensively studied in the literature.Unlike packet transmission over a single channel, in a multichannel communication system, multiple packets are sent at a time, one packet per channel, and packet transmission errors can occur across every channel. To implement error control through retransmission of packets in a multichannel communication system, an ARQ protocol has been generalized to allow concurrent transmission of multiple packets.

      In this  we consider a multichannel SW-ARQ protocol for both time-invariant and time-varying channel models. We analyze performance of the resequencing buffer in terms of the resequencing buffer occupancy, which is the number of packets waiting in the resequencing buffer for delivery, and the resequencing delay, defined as the waiting time of a packet in the resequencing buffer, in steady state.

Modules:

1.     Resequents.

2.  Clients.

Module Description:

Resequents:

                      It is actually a which is the average number of packets successfully transmitted per unit of time, and the mean transmission delay, which is the average time between the instant when a packet is transmitted for the first time and the instant when it is successfully received, have been derived. Meanwhile,Wu et al.  conducted a throughput performance study on multichannel ARQ(AUTOMATIC-REPEAT-REQUEST) protocols based on the same model as that in . Fujii et al.analyzed the transmission-delay distribution function of GBN-ARQ for parallel channels that have the same transmission rate but possibly different  time-invariant error rates. Recently, Ding and Rice , considered ARQ protocols for parallel channels in which each channel may have a unique transmission rate and error rate. Expressions for the throughput and the mean  transmission delay have been derived in  and . The resequencing issue in multichannel ARQ protocols was first addressed by Shacham and Chin . In that study, they conducted a resequencing analysis (e.g., the resequencing buffer occupancy and the resequencing delay) for SR-ARQ over parallel channels, all of which have the same transmission rate but possibly different time-invariant error rates.

The reserve side first we have to select the receiver location which is store the files to store at receiver machine .after click on server start it show the button which is beside of the button it change that color in to green .and one popup message shows to us ‘server is started’.it is shows the segment s moving into the server that it  is automatically give the green colour for that particular segment if it get full segment and it will send  acknowledgement to the sender based on that it is receive the segment if it is incorrect,other wise it show the blue color whether it is incorrect format of the segment, it showing the orange color when the segment is not received.

Clients:

                Several performance studies on multichannel ARQ protocols have been reported in literature. Chang and Yang  studied performance of the three classical ARQ protocols for multiple identical channels (i.e., all channels have the same transmission rate and the same time-invariant error rate). In that study, exactexpressions for the throughput, which is the average number of  packets successfully transmitted per unit of time.

In this client system User is select one file using upload file and it split it in to ten segments .if we need to see the loose of the segment  here we have to select check box before sending.

After click on send button it show the flow of the execution.we can able to see the flow of the each segment moving  ,it is automatically give the green colour for that particular segment if it get positive acknowledgement ,other wise it show the blue color whether it is negative acknowledgement, it showing the orange color when the segment is not sent. After sending five segments it show the one message like first part is completed. After sending the total segments it shows the message like ‘completed successfully’.

Hardware Requirements:

•         System                : Pentium IV 2.4 GHz.

•         Hard Disk            : 40 GB.

•         Floppy Drive        : 1.44 Mb.

•         Monitor                : 15 VGA Colour.

•         Mouse                 : Logitech.

•         Ram                     : 256 Mb.

Software Requirements:

•         Operating system         : - Windows XP Professional.

•         Front End                        : - Asp .Net 2.0.

•         Coding Language         : - Visual C# .Net.

•         Back-End                        : - Sql Server 2000. 

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