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Seeking for an Optimal Route in IEEE 802.11e Ad-Hoc Networks

Publication . Ferro, Joao M.; Cabral, Orlando Manuel Brito; Velez, Fernando J.

In this paper we present several different approaches to a routing calculation in an ad-hoc network. By using different weights for each link, each algorithm generates a different path, with its own number of hops and maximum throughput. Tests were performed in our own IEEE 802.11e simulator and the results allow to conclude that the cross-layer approach has advantages over the traditional one. In fact, our proposals delivers up to three times more packets than the standard one, whilst diminishing the end-to-end delay. Results show that the proposal which privileges users with a baud rate near the maximum possible achieves better performance than the others. A baud rate near the maximum corresponds to links with the highest signal to interference-plus-noise ratio. The proposed technique privileges the use of paths with a larger number of hops, and reduces the packet end-to-end delay.

2009-09Conference object

Open access

Cross-layer multi-hop simulator for ad-hoc IEEE 802.11e

Publication . Ferro, João Miguel; Velez, Fernando José

The purpose of this paper is to present a custom-made cross-layer network simulator for wireless IEEE 802.11e in a multihop environment. A previous work of our research team created a simulator just for the physical plus MAC layers, which in this work was adapted to model the transmission of a packet from a source to a destination using intermediate nodes. Some initial tests were performed using a simple routing algorithm, and the results obtained from these tests indicate that the system is capable of deliver the packets regardless of the source/destination, and successfully calculates several metrics such as end-to-end delay and number of packets lost.

2008-07Conference object

Open access

Multi-Hop Simulator for Ad-Hoc IEEE 802.11e

Publication . Ferro, João Miguel; Velez, Fernando José

Abstract|This work addresses the development of a cross-layer wireless network simulator for IEEE 802.11e in a multi-hop environment. Based on a previous simulator created by our research team for physical plus MAC layers, it involved the upgrade of a previous version of that simulator to model the transmission of packets from the source to the destination using intermediate nodes. From the results obtained for an initial routing algorithm, one can conclude that the system is capable of deliver the packets regardless of the source/destination, and successfully calculate several metrics such as end-to-end delay and number of packets lost.

2008-07Conference object

Open access

Optimization of Multi-Service IEEE 802.11e Block Acknowledgement

Publication . Cabral, Orlando; Velez, Fernando José; Mihovska, Albena Dimitrova; Prasad, Neeli

Optimization of IEEE 802.11e MAC protocol performance is addressed by modifying several parameters left open in the standard, like block size and acknowledgement policies in order to improve the channel efficiency. The use of small block sizes leads to a high overhead caused by the negotiation on the other hand, the use of large block sizes causes long delays, which can affect negatively real-time applications (or delay sensitive applications). An event driven simulator was developed, and results with a single service and several services running simultaneously were extracted. By using the Block Acknowledgement (BA) procedure, for video and background traffics in a single service situation, the capacity was improved in the case when the number of stations is equal or higher than 16 and 12, respectively. However, for lower values of the number of stations, the use of BA leads to a slightly worst system performance. In a scenario with mixture of services the most advised block size is 12 (less delay in a highly loaded scenario). The number of supported user (total) increases from 30 to 35.

2009-01Conference object

Open access