IEEE Journal on Selected Areas in Communications, 2015
Offloading traffic through opportunistic communications has been recently proposed as a way to re... more Offloading traffic through opportunistic communications has been recently proposed as a way to relieve the current overload of cellular networks. Opportunistic communication can occur when mobile device users are (temporarily) in each other's proximity, such that the devices can establish a local peer-to-peer connection (e.g., via Bluetooth). Since opportunistic communication is based on the spontaneous mobility of the participants, it is inherently unreliable. This poses a serious challenge to the design of any cellular offloading solutions, that must meet the applications' requirements. In this paper, we address this challenge from an optimization analysis perspective, in contrast to the existing heuristic solutions. We first model the dissemination of content (injected through the cellular interface) in an opportunistic network with heterogeneous node mobility. Then, based on this model, we derive the optimal content injection strategy, which minimizes the load of the cellular network while meeting the applications' constraints. Finally, we propose an adaptive algorithm based on control theory that implements this optimal strategy without requiring any data on the mobility patterns or the mobile nodes' contact rates. The proposed approach is extensively evaluated with both a heterogeneous mobility model as well as real-world contact traces, showing that it substantially outperforms previous approaches proposed in the literature.
IEEE Workshop on High Performance Switching and Routing, 2002
The Internet is now widely expected to become an important communication infrastructure of societ... more The Internet is now widely expected to become an important communication infrastructure of society, and therefore it is no longer sufficient to simply be able to provide connections. A higher quality of service (QoS) in communications is increasingly being required. As a new framework for providing QoS services, DiffServ is undergoing a speedy standardization process at the IETF. DiffServ not
The Internet is now widely expected to become an important communication infrastructure of the so... more The Internet is now widely expected to become an important communication infrastructure of the society, and therefore it is no longer sufficient to simply be able to provide connections. A higher quality of service (QoS) in communications is increasingly being required. As a new framework for providing QoS services, DiffServ is undergoing a speedy standardization process at the IETF. DiffServ not only can offer tiered level of services, but can also provide guaranteed QoS to a certain extent. In this paper, we examine a single DiffServ node model which utilizes token bucket as the policing mechanism, and propose a way of configuring various control parameters in order to accommodate various UDP/TCP traffic. Then, through simulation, we evaluate the throughput characteristics for various cases when TCP and UDP are mixed or separated in different queues, and study the appropriateness of the configurations. The results indicate that the throughputs can be maintained as specified in the Service Level Agreements (SLA) over a considerably wide range of bucket sizes and discard thresholds in the QoS control mechanism.
Workshop on High Performance Switching and Routing, Merging Optical and IP Technologie, 2002
Abstract The Internet is now widely expected to become an important communication infrastructure ... more Abstract The Internet is now widely expected to become an important communication infrastructure of the society, and therefore it is no longer sufficient to simply be able to provide connections. A higher quality of service (QoS) in communications is increasingly being ...
Proceedings. 2006 31st IEEE Conference on Local Computer Networks, 2006
A simple and accurate packet delay distribution analysis is presented for the RTS/CTS access sche... more A simple and accurate packet delay distribution analysis is presented for the RTS/CTS access scheme of the IEEE 802.11 Distributed Coordination Function (DCF). The packet delay distribution is effectively studied by developing an analytical model that calculates the probability that a packet is successfully transmitted after experiencing a delay time equal to a given value. The model uses simple mathematical relations and provides accurate delay distribution curves. The accuracy of the analytical model is verified by simulations.
2006 IEEE 17th International Symposium on Personal, Indoor and Mobile Radio Communications, 2006
A simple, effective and accurate packet delay distribution analysis is presented for the IEEE 802... more A simple, effective and accurate packet delay distribution analysis is presented for the IEEE 802.11 distributed coordination function (DCF). The packet delay distribution is effectively studied by developing an analytical model that calculates the probability that a packet is successfully transmitted after experiencing a delay time equal to a given value. The model uses simple mathematical relations and provides fast and accurate delay distribution curves. The accuracy of the analytical model is verified by simulations
Proceedings 23rd Annual Conference on Local Computer Networks. LCN'98 (Cat. No.98TB100260), 1998
Active networks allow code to be loaded dynamically into network nodes at run-time. This code can... more Active networks allow code to be loaded dynamically into network nodes at run-time. This code can perform tasks specific to a stream of packets or even a single packet. In this paper we compare two active network architectures: the Active Node Transfer System (ANTS) and the Messen- ger System (M0). We have implemented a robust audio mul- ticast protocol and
The distribution of the delay is a very important measure to determine the performance of a WLAN.... more The distribution of the delay is a very important measure to determine the performance of a WLAN. Indeed, realtime applications typically require that their packets reach their destination within a certain delay with a given probability, and to guarantee this it is necessary to perform the computation of the delay distribution. In this paper we develop a novel method to compute the delay distribution of IEEE 802.11 Distributed Coordination Function (DCF) for a WLAN where the stations transmit packets of variable length. We develop an analytical model that applies to basic, RTS/CTS, and hybrid (coexistence of basic and RTS/CTS) access modes. A simulation model is used to validate the analysis.
In this paper, we first present an analytical model to study the distribution of the backoff dela... more In this paper, we first present an analytical model to study the distribution of the backoff delay in an 802.11 DCF WLAN under saturation conditions. We show that, with our method, the probability that the backoff delay is below a given threshold can be computed accurately and efficiently. Then, we extend our backoff delay distribution model to analyze the end-to-end delay, and propose an admission control algorithm based on this analysis. The proposed algorithm is evaluated in a mixed environment with voice and data stations, and simulation results confirm that it effectively provides voice stations with end-to-end delay guarantees. The algorithm is also evaluated in terms of computational cost and shown to be efficient enough for run-time usage. q
ABSTRACT This paper provides an in-depth understanding of the per-frame energy consumption behavi... more ABSTRACT This paper provides an in-depth understanding of the per-frame energy consumption behavior in 802.11 Wireless LAN devices. Extensive measurements are performed for 7 devices of different types (wireless routers, smart phones, tablets and embedded devices), and for both UDP and TCP traffic. Experimental results unveil that a substantial fraction of energy consumption, hereafter descriptively named cross-factor, may be ascribed to each individual frame while it crosses the protocol stack (OS, driver, NIC) and is independent of the frame size. Our findings, summarized in a convenient energy consumption model, contrast traditional models which (implicitly) amortize such energy cost component in a fixed baseline cost or in a toll proportional to the frame size, and raise the alert that, in some cases, conclusions drawn using traditional energy models may be fallacious.
Proceedings of the 9th ACM SIGCOMM conference on Internet measurement conference - IMC '09, 2009
WLAN devices based on CSMA/CA access schemes have become a fundamental component of network deplo... more WLAN devices based on CSMA/CA access schemes have become a fundamental component of network deployments. In such wireless scenarios, traditional networking applications, tools, and protocols, with their built-in measurement techniques, are usually run unchanged. However, their actual interaction with the dynamics of underlying wireless systems is not yet fully understood. A relevant example of such built-in techniques is bandwidth measurement. When considering WLAN environments, various preliminary studies have shown that the application of results obtained in wired setups is not straightforward. Indeed, the contention for medium sharing among multiple users inherent to CSMA/CA access schemes has remarkable consequences on the behavior of and results obtained by bandwidth measurement techniques. In this paper, we focus on evaluating the effect of CSMA/CA-based contention on active bandwidth measurement techniques. As a result, it presents the rate response curve in steady state of a system with both FIFO and CSMA/CA-based contending cross-traffic. We also find out that the distribution of access delay shows a transient regime before reaching a stationary state. The duration of such transient regime is characterized and bounded. We also show how dispersion-based measurements that use a short number of probing packets are biased measurements of the achievable throughput, the origin of this bias lying on the transient detected in the access delay of probing packets. Overall, the results presented in this paper have several consequences that are expected to influence the design of Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee.
Eurasip Journal on Wireless Communications and Networking, 2010
A lot of attention has been given to multihop wireless networks lately, but further research-in p... more A lot of attention has been given to multihop wireless networks lately, but further research-in particular, through experimentation-is needed. This attention has motivated an increase in the number of 802.11-based deployments, both indoor and outdoor. These testbeds, which require a significant amount of resources during both deployment and maintenance, are used to run measurements in order to analyze and understand the limitation and differences between analytical or simulation-based figures and the results from real-life experimentation. This paper makes two major contributions: (i) first, we describe a novel wireless multihop testbed, which we name FloorNet, that is deployed and operated under the false floor of a lab in our Computer Science building. This false floor provides a strong physical protection that prevents disconnections or misplacements, as well as radio shielding (to some extent) thanks to the false floor panels-this later feature is assessed through experimentation; (ii) second, by running exhaustive and controlled experiments we are able to analyze the performance limits of commercial off-theshelf hardware, as well as to derive practical design criteria for the deployment and configuration of mesh networks. These results both provide valuable insights of wireless multihop performance and prove that FloorNet constitutes a valuable asset to research on wireless mesh networks.
In some wireless ad-hoc networks it is not possible to rely on carrier-sense mechanisms to preven... more In some wireless ad-hoc networks it is not possible to rely on carrier-sense mechanisms to prevent collisions. In this article we suggest a MAC protocol that reaches collision-free operation in sparse ad-hoc wireless networks when all the stations are saturated. The basic idea is to use a random backoff after failed transmissions and a deterministic backoff after successful transmissions. Each of the participating stations can configure its own backoff parameter after collecting information from its neighborhood. Then the system enters in a transient-state until collisionfree operation is reached. We assess the duration of the transient-state and other performance metrics for an example scenario and finally we discuss two options to incorporate reception acknowledgements.
2009 IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks & Workshops, 2009
When there is no wired connectivity, wireless mesh networks (WMNs) can provide Internet access wi... more When there is no wired connectivity, wireless mesh networks (WMNs) can provide Internet access with lower cost and greater flexibility than traditional approaches. This has motivated the design of new protocols and algorithms for WMNs, and recently the deployment of experimental prototypes. In this paper we add to these previous works with the performance evaluation of a first CARMEN deployment, with the following distinguishing features: i) it is an indoor deployment, ii) it is used by real users to connect to the Internet, and iii) it is built using off-the-shelf hardware. The results show that mesh technology can provide users with a satisfactory Internet experience, and motives further research along this line.
2008 IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications, 2008
Current Internet use is evolving, users are becoming mobile and are expecting data services on th... more Current Internet use is evolving, users are becoming mobile and are expecting data services on the go. This fact presents big challenges and opportunities to operators, which see the increase in data services as a big market still to be exploited. However, current cellular technologies cannot accommodate the demand that will arise when the true Mobile Internet evolves. Addressing these challenges, we present the CARMEN project, the vision of which is to extend operators' infrastructure by providing carrier grade services through a heterogeneous wireless mesh. The CARMEN architecture will provide enough bandwidth to cope with users' expectations at a reduced cost, thereby generating major benefits to operators and users.
In this paper, we present a model to analyze the throughput and delay performance of the EDCA mec... more In this paper, we present a model to analyze the throughput and delay performance of the EDCA mechanism under non saturation conditions. The main strength of our model is that it can be used to analyze generic source models, as it neither makes any assumption on the source's arrival process nor requires all packets be of the same length. Simulation results confirm the accuracy of our model under a variety of realistic source models, including (i) typical arrival processes for voice, video, and data traffic, and (ii) packet length distributions derived from measurements.
The enhanced distributed channel access (EDCA) mechanism of the IEEE 802.11e standard provides qu... more The enhanced distributed channel access (EDCA) mechanism of the IEEE 802.11e standard provides quality-ofservice (QoS) support through service differentiation by using different medium-access-control (MAC) parameters for different stations. The configuration of these parameters, however, is still an open research challenge, as the standard provides only a set of fixed recommended values that do not take into account the current wireless local area network (WLAN) conditions and, therefore, lead to suboptimal performance. In this paper, we propose a novel algorithm for EDCA that, given the throughput and delay requirements of the stations that are present in the WLAN, computes the optimal configuration of the EDCA parameters. We first present a throughput and delay analysis that provides the mathematical foundation upon which our algorithm is based. This analysis is validated through simulations of different traffic sources (both data and real time) and EDCA configurations. We then propose a mechanism to derive the optimal configuration of the EDCA parameters, given a set of performance criteria for throughput and delay. We assess the effectiveness of the configuration provided by our algorithm by comparing it against 1) the recommended values by the standard, 2) the results from an exhaustive search over the parameter space, and 3) previous configuration proposals, which are both standard and nonstandard compliant. Results show that our configuration outperforms all other approaches.
IEEE Journal on Selected Areas in Communications, 2015
Offloading traffic through opportunistic communications has been recently proposed as a way to re... more Offloading traffic through opportunistic communications has been recently proposed as a way to relieve the current overload of cellular networks. Opportunistic communication can occur when mobile device users are (temporarily) in each other's proximity, such that the devices can establish a local peer-to-peer connection (e.g., via Bluetooth). Since opportunistic communication is based on the spontaneous mobility of the participants, it is inherently unreliable. This poses a serious challenge to the design of any cellular offloading solutions, that must meet the applications' requirements. In this paper, we address this challenge from an optimization analysis perspective, in contrast to the existing heuristic solutions. We first model the dissemination of content (injected through the cellular interface) in an opportunistic network with heterogeneous node mobility. Then, based on this model, we derive the optimal content injection strategy, which minimizes the load of the cellular network while meeting the applications' constraints. Finally, we propose an adaptive algorithm based on control theory that implements this optimal strategy without requiring any data on the mobility patterns or the mobile nodes' contact rates. The proposed approach is extensively evaluated with both a heterogeneous mobility model as well as real-world contact traces, showing that it substantially outperforms previous approaches proposed in the literature.
IEEE Workshop on High Performance Switching and Routing, 2002
The Internet is now widely expected to become an important communication infrastructure of societ... more The Internet is now widely expected to become an important communication infrastructure of society, and therefore it is no longer sufficient to simply be able to provide connections. A higher quality of service (QoS) in communications is increasingly being required. As a new framework for providing QoS services, DiffServ is undergoing a speedy standardization process at the IETF. DiffServ not
The Internet is now widely expected to become an important communication infrastructure of the so... more The Internet is now widely expected to become an important communication infrastructure of the society, and therefore it is no longer sufficient to simply be able to provide connections. A higher quality of service (QoS) in communications is increasingly being required. As a new framework for providing QoS services, DiffServ is undergoing a speedy standardization process at the IETF. DiffServ not only can offer tiered level of services, but can also provide guaranteed QoS to a certain extent. In this paper, we examine a single DiffServ node model which utilizes token bucket as the policing mechanism, and propose a way of configuring various control parameters in order to accommodate various UDP/TCP traffic. Then, through simulation, we evaluate the throughput characteristics for various cases when TCP and UDP are mixed or separated in different queues, and study the appropriateness of the configurations. The results indicate that the throughputs can be maintained as specified in the Service Level Agreements (SLA) over a considerably wide range of bucket sizes and discard thresholds in the QoS control mechanism.
Workshop on High Performance Switching and Routing, Merging Optical and IP Technologie, 2002
Abstract The Internet is now widely expected to become an important communication infrastructure ... more Abstract The Internet is now widely expected to become an important communication infrastructure of the society, and therefore it is no longer sufficient to simply be able to provide connections. A higher quality of service (QoS) in communications is increasingly being ...
Proceedings. 2006 31st IEEE Conference on Local Computer Networks, 2006
A simple and accurate packet delay distribution analysis is presented for the RTS/CTS access sche... more A simple and accurate packet delay distribution analysis is presented for the RTS/CTS access scheme of the IEEE 802.11 Distributed Coordination Function (DCF). The packet delay distribution is effectively studied by developing an analytical model that calculates the probability that a packet is successfully transmitted after experiencing a delay time equal to a given value. The model uses simple mathematical relations and provides accurate delay distribution curves. The accuracy of the analytical model is verified by simulations.
2006 IEEE 17th International Symposium on Personal, Indoor and Mobile Radio Communications, 2006
A simple, effective and accurate packet delay distribution analysis is presented for the IEEE 802... more A simple, effective and accurate packet delay distribution analysis is presented for the IEEE 802.11 distributed coordination function (DCF). The packet delay distribution is effectively studied by developing an analytical model that calculates the probability that a packet is successfully transmitted after experiencing a delay time equal to a given value. The model uses simple mathematical relations and provides fast and accurate delay distribution curves. The accuracy of the analytical model is verified by simulations
Proceedings 23rd Annual Conference on Local Computer Networks. LCN'98 (Cat. No.98TB100260), 1998
Active networks allow code to be loaded dynamically into network nodes at run-time. This code can... more Active networks allow code to be loaded dynamically into network nodes at run-time. This code can perform tasks specific to a stream of packets or even a single packet. In this paper we compare two active network architectures: the Active Node Transfer System (ANTS) and the Messen- ger System (M0). We have implemented a robust audio mul- ticast protocol and
The distribution of the delay is a very important measure to determine the performance of a WLAN.... more The distribution of the delay is a very important measure to determine the performance of a WLAN. Indeed, realtime applications typically require that their packets reach their destination within a certain delay with a given probability, and to guarantee this it is necessary to perform the computation of the delay distribution. In this paper we develop a novel method to compute the delay distribution of IEEE 802.11 Distributed Coordination Function (DCF) for a WLAN where the stations transmit packets of variable length. We develop an analytical model that applies to basic, RTS/CTS, and hybrid (coexistence of basic and RTS/CTS) access modes. A simulation model is used to validate the analysis.
In this paper, we first present an analytical model to study the distribution of the backoff dela... more In this paper, we first present an analytical model to study the distribution of the backoff delay in an 802.11 DCF WLAN under saturation conditions. We show that, with our method, the probability that the backoff delay is below a given threshold can be computed accurately and efficiently. Then, we extend our backoff delay distribution model to analyze the end-to-end delay, and propose an admission control algorithm based on this analysis. The proposed algorithm is evaluated in a mixed environment with voice and data stations, and simulation results confirm that it effectively provides voice stations with end-to-end delay guarantees. The algorithm is also evaluated in terms of computational cost and shown to be efficient enough for run-time usage. q
ABSTRACT This paper provides an in-depth understanding of the per-frame energy consumption behavi... more ABSTRACT This paper provides an in-depth understanding of the per-frame energy consumption behavior in 802.11 Wireless LAN devices. Extensive measurements are performed for 7 devices of different types (wireless routers, smart phones, tablets and embedded devices), and for both UDP and TCP traffic. Experimental results unveil that a substantial fraction of energy consumption, hereafter descriptively named cross-factor, may be ascribed to each individual frame while it crosses the protocol stack (OS, driver, NIC) and is independent of the frame size. Our findings, summarized in a convenient energy consumption model, contrast traditional models which (implicitly) amortize such energy cost component in a fixed baseline cost or in a toll proportional to the frame size, and raise the alert that, in some cases, conclusions drawn using traditional energy models may be fallacious.
Proceedings of the 9th ACM SIGCOMM conference on Internet measurement conference - IMC '09, 2009
WLAN devices based on CSMA/CA access schemes have become a fundamental component of network deplo... more WLAN devices based on CSMA/CA access schemes have become a fundamental component of network deployments. In such wireless scenarios, traditional networking applications, tools, and protocols, with their built-in measurement techniques, are usually run unchanged. However, their actual interaction with the dynamics of underlying wireless systems is not yet fully understood. A relevant example of such built-in techniques is bandwidth measurement. When considering WLAN environments, various preliminary studies have shown that the application of results obtained in wired setups is not straightforward. Indeed, the contention for medium sharing among multiple users inherent to CSMA/CA access schemes has remarkable consequences on the behavior of and results obtained by bandwidth measurement techniques. In this paper, we focus on evaluating the effect of CSMA/CA-based contention on active bandwidth measurement techniques. As a result, it presents the rate response curve in steady state of a system with both FIFO and CSMA/CA-based contending cross-traffic. We also find out that the distribution of access delay shows a transient regime before reaching a stationary state. The duration of such transient regime is characterized and bounded. We also show how dispersion-based measurements that use a short number of probing packets are biased measurements of the achievable throughput, the origin of this bias lying on the transient detected in the access delay of probing packets. Overall, the results presented in this paper have several consequences that are expected to influence the design of Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee.
Eurasip Journal on Wireless Communications and Networking, 2010
A lot of attention has been given to multihop wireless networks lately, but further research-in p... more A lot of attention has been given to multihop wireless networks lately, but further research-in particular, through experimentation-is needed. This attention has motivated an increase in the number of 802.11-based deployments, both indoor and outdoor. These testbeds, which require a significant amount of resources during both deployment and maintenance, are used to run measurements in order to analyze and understand the limitation and differences between analytical or simulation-based figures and the results from real-life experimentation. This paper makes two major contributions: (i) first, we describe a novel wireless multihop testbed, which we name FloorNet, that is deployed and operated under the false floor of a lab in our Computer Science building. This false floor provides a strong physical protection that prevents disconnections or misplacements, as well as radio shielding (to some extent) thanks to the false floor panels-this later feature is assessed through experimentation; (ii) second, by running exhaustive and controlled experiments we are able to analyze the performance limits of commercial off-theshelf hardware, as well as to derive practical design criteria for the deployment and configuration of mesh networks. These results both provide valuable insights of wireless multihop performance and prove that FloorNet constitutes a valuable asset to research on wireless mesh networks.
In some wireless ad-hoc networks it is not possible to rely on carrier-sense mechanisms to preven... more In some wireless ad-hoc networks it is not possible to rely on carrier-sense mechanisms to prevent collisions. In this article we suggest a MAC protocol that reaches collision-free operation in sparse ad-hoc wireless networks when all the stations are saturated. The basic idea is to use a random backoff after failed transmissions and a deterministic backoff after successful transmissions. Each of the participating stations can configure its own backoff parameter after collecting information from its neighborhood. Then the system enters in a transient-state until collisionfree operation is reached. We assess the duration of the transient-state and other performance metrics for an example scenario and finally we discuss two options to incorporate reception acknowledgements.
2009 IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks & Workshops, 2009
When there is no wired connectivity, wireless mesh networks (WMNs) can provide Internet access wi... more When there is no wired connectivity, wireless mesh networks (WMNs) can provide Internet access with lower cost and greater flexibility than traditional approaches. This has motivated the design of new protocols and algorithms for WMNs, and recently the deployment of experimental prototypes. In this paper we add to these previous works with the performance evaluation of a first CARMEN deployment, with the following distinguishing features: i) it is an indoor deployment, ii) it is used by real users to connect to the Internet, and iii) it is built using off-the-shelf hardware. The results show that mesh technology can provide users with a satisfactory Internet experience, and motives further research along this line.
2008 IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications, 2008
Current Internet use is evolving, users are becoming mobile and are expecting data services on th... more Current Internet use is evolving, users are becoming mobile and are expecting data services on the go. This fact presents big challenges and opportunities to operators, which see the increase in data services as a big market still to be exploited. However, current cellular technologies cannot accommodate the demand that will arise when the true Mobile Internet evolves. Addressing these challenges, we present the CARMEN project, the vision of which is to extend operators' infrastructure by providing carrier grade services through a heterogeneous wireless mesh. The CARMEN architecture will provide enough bandwidth to cope with users' expectations at a reduced cost, thereby generating major benefits to operators and users.
In this paper, we present a model to analyze the throughput and delay performance of the EDCA mec... more In this paper, we present a model to analyze the throughput and delay performance of the EDCA mechanism under non saturation conditions. The main strength of our model is that it can be used to analyze generic source models, as it neither makes any assumption on the source's arrival process nor requires all packets be of the same length. Simulation results confirm the accuracy of our model under a variety of realistic source models, including (i) typical arrival processes for voice, video, and data traffic, and (ii) packet length distributions derived from measurements.
The enhanced distributed channel access (EDCA) mechanism of the IEEE 802.11e standard provides qu... more The enhanced distributed channel access (EDCA) mechanism of the IEEE 802.11e standard provides quality-ofservice (QoS) support through service differentiation by using different medium-access-control (MAC) parameters for different stations. The configuration of these parameters, however, is still an open research challenge, as the standard provides only a set of fixed recommended values that do not take into account the current wireless local area network (WLAN) conditions and, therefore, lead to suboptimal performance. In this paper, we propose a novel algorithm for EDCA that, given the throughput and delay requirements of the stations that are present in the WLAN, computes the optimal configuration of the EDCA parameters. We first present a throughput and delay analysis that provides the mathematical foundation upon which our algorithm is based. This analysis is validated through simulations of different traffic sources (both data and real time) and EDCA configurations. We then propose a mechanism to derive the optimal configuration of the EDCA parameters, given a set of performance criteria for throughput and delay. We assess the effectiveness of the configuration provided by our algorithm by comparing it against 1) the recommended values by the standard, 2) the results from an exhaustive search over the parameter space, and 3) previous configuration proposals, which are both standard and nonstandard compliant. Results show that our configuration outperforms all other approaches.
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