Browsing by Author "Segarra, Alberto"
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- Event-Driven Simulation for IEEE 802.11e OptimizationPublication . Cabral, Orlando Manuel Brito; Segarra, Alberto; Velez, Fernando J.This work provides the specification of a PHY and MAC layers simulator that allows to evaluate the IEEE 802.11e service quality. A detailed state transition diagram is presented along with a description of the related attributes and methods, an identification of the associated events and input variables, and a description of functions for events. For validation purposes, results of the goodput as a function of the signal to interference noise ratio were obtained with an error margin lower than 10%. Higher values are found for the goodput for background and video services, mainly because the frames transmitted in these services are longer than the voice application ones. However, the number of supported users is higher for voice. This simulator will allow for tuning-up several parameters like the ones related to how to use BlockACK, normal ACK, and NO ACK policies.
- IEEE 802.11E Block Acknowledgement PoliciesPublication . Cabral, Orlando Manuel Brito; Segarra, Alberto; Velez, Fernando J.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.
- Implementation of IEEE 802.11e Block Acknowledgement PoliciesPublication . Cabral, Orlando; Segarra, Alberto; Velez, Fernando JoséOptimisation of IEEE 802.11e MAC protocol performance can be performed by modifying several parameters left open in the standard, like buffer size and acknowledgement policies. In this work, an event driven simulator was developed, and a comparison of the results between the case of standalone services and several services supported simultaneously was addressed. With only a single service, higher values for the goodput are obtained for video and background (BK) traffics, while the lowest is found for the voice application. The number of supported users is higher for voice. With mixtures of traffic, when the number of station is small the goodput is lower for voice. However, for higher number of station, the lowest values of the goodput occur for background traffic. By using the Block Acknowledgement (ACK) procedure, for video and BK traffics, the capacity is improved when the number of station is equal or higher than 16 and 12, respectively. From a detailed analysis of the video application, a reduction of more than 40% was achieved in the delay.
- Implementation of IEEE 802.11e block acknowledgement policies based on the buffer sizePublication . Cabral, Orlando; Segarra, Alberto; Velez, Fernando J.Optimization of IEEE 802.11e MAC protocol performance is done by modifying several parameters left open in the standard, like buffer size and acknowledgement policies. By using the developed event-driven simulator, results were extracted with single and multi-service. With only a single service, higher values for the goodput are obtained for video and background (BK) traffics in comparison with the voice (VO) application. Besides, the number of supported user is higher for voice. With mixtures of traffic, when the number of station is small the goodput is lower for VO. However, for higher number of station, the lowest values for the goodput occur for background traffic. By using the Block Acknowledgement (ACK) procedure, for video and BK traffics, the capacity is improved when the number of station is equal or higher than 16 and 12, respectively. From a detailed analysis of the video application, a reduction of more than 40% was achieved in the delay. However, a clear trend is not identified for the optimum block size.
- Implementation of Multi-service IEEE 802.11e Block Acknowledgement PoliciesPublication . Cabral, Orlando Manuel Brito; Segarra, Alberto; Velez, Fernando J.Optimisation of IEEE 802.11e MAC protocol performance can be performed by modifying several parameters left open in the standard, like buffer size and acknowledgement policies. In this work, an event driven simulator was developed, and a comparison of the results between the case of standalone services and several services supported simultaneously was addressed. With only a single service, higher values for the goodput are obtained for video and background (BK) traffics, while the lowest ones are found for the voice application. Besides, the number of supported users is higher for voice. With mixtures of traffic, when the number of station is small the goodput is lower for voice. However, for higher number of station, the lowest values of the goodput occur for background traffic. By using the Block Acknowledgement 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 Block Acknowledgements 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 total number of supported user increases from 30 to 35.
- Simulation of IEEE 802.11e in the context of interoperabilityPublication . Cabral, Orlando; Segarra, Alberto; Velez, Fernando JoséThis work provides the specification of a MAC layer simulator that evaluates the service quality in WiFi, and presents initial results as a stand-alone simulator. The simulator will account for inter-working with WiMAX and HSDPA in the context of the IT-MOTION tool. Higher throughputs are found for the FTP service and for the video service, mainly because the frames transmitted in these services are longer than the ones for the voice application. However, the number of supported users is higher for voice. This simulator will allow for tuning-up several parameters like the ones related to how to use BlockACK, normal ACK, and NO ACK policies.