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The Supplementation of Backoff Rules By TDMA Technique to Improve Data Rate in Mobile Adhoc Networks (MANET)
Blekinge Institute of Technology, School of Engineering.
Blekinge Institute of Technology, School of Engineering.
2009 (English)Independent thesis Advanced level (degree of Master (Two Years))Student thesis
Abstract [en]

Those Networks in which two or more than two mobile nodes are communicating with other are considered to be Mobile networks, Now the Mobile Ad Hoc Networks are the same kind of networks but they can be implemented at the time of disasters or in the military purpose when there is a need of Ad Hoc Networks which can take over the existing Mobile networks, therefore the only reason which gives it the name of Ad Hoc Networks is that is can be implemented anywhere without any centralized infrastructures. Mobile Ad Hoc network represents a system of wireless mobile nodes that can self organize freely and for the temporary purpose in the network technology, they can be applied anywhere as the MANET reduces the complexity of the Infrastructures. Routing traffic between MANET nodes experience collisions, end to end delay (E2E) and total loss of data packets due to limited bandwidth between nodes. These result in poor Quality of Service (QoS) and E2E delay throughput. In this paper we have proposed the application of time division multiple access (TDMA) technique to improve data rate and reduce control and data over-head collisions. We compared the existing normal routing scheme and the TDMA based scheme. TDMA allows a number of clients to access a single radio-frequency channel without interference by allocating unique time slots to each user within each channel, reducing the loss of packets and improving the data rate thereby delivering QoS to the clients

Abstract [sv]

We have proposed TDMA technique, a BEBA (Binary Exponential Backoff Algorithm) based time dependent data rate improvement technique in MANET, which characterizes improvement of data by reducing loss of control packet and collision effect over a limited channel capacity. Medium capturing is governed by backoff rules. These rules help prevent the collisions between nodes but cannot totally avoid them. When the number of nodes in a medium increases considerably, the avoidance of collision becomes more difficult and bandwidth loss is inevitable. We observe inefficient data throughput and E2E delay within a multi hop transmission between mobile nodes as an inherent problem. Collisions between nodes increase dramatically when their number increases in a location. Lost packets and retransmissions cause a decrease in data rates. Thus TDMA technique to control these collisions is quite helpful. The purpose of the project is to show the supplementation of backoff rules by TDMA technique to reduce collisions and increase data rate. Higher data rate is achieved because of the avoidance of collisions and improved performance of the backoff algorithm. Advanced On Demand Vector routing protocol (AODV) is used for routing between the nodes. MAC used for these nodes is IEEE 802.11. We have devised a technique in which collision is minimized by combining the wireless medium backoff rules with TDMA. TDMA helps in dividing a large number of nodes into groups of smaller number of nodes. At any given instant, communication within a single group is possible and whole medium is dedicated to it. Although a node can transmit only when its group gets the TDMA time slot, the throughput is increased considerably because of less transmitting nodes per time slot. TDMA is used for allowing many users to utilize a common channel. Without TDMA such senders will always collide. We have used TDMA for avoidance of collisions although the same channel can be utilized simultaneously by all the users. In TDMA only one pair of sender and receiver is active. Thus collisions are avoided. Although each pair transmits for 1/8 of a second, data rate is much higher than the situation when they transmit all the time. We have compared the existing normal routing scheme and the TDMA based scheme using NS2 Simulator. This scheme, governed by packet generation and transmission over allocated time slot using the available bandwidth guarantees appreciable reduction in data loss rate and substantial improvement in link capacity utilization. The numerical results obtained shows that the performance of TDMA technique is better when compared to the current Normal route technique.

Place, publisher, year, edition, pages
2009. , 86 p.
Keyword [en]
Energy Conservation, Routing, Time Divistion Multiple Access, Adhoc On Demand Routing Protocol
National Category
URN: urn:nbn:se:bth-2177Local ID: diva2:829444
+46-760896740Available from: 2015-04-22 Created: 2009-08-31 Last updated: 2015-06-30Bibliographically approved

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