Search results for "wireless LAN"
showing 10 items of 38 documents
A space-division time-division multiple access scheme for high throughput provisioning in WLANs
2005
Directional antennas may dramatically increase the capacity of a Wireless LAN by allowing several stations to simultaneously communicate. Since deployment of directive/smart antennas on the customer's terminals is awkward (for technological, cost, robustness, and convenience reasons) it is of interest to deploy advanced antenna solutions only at the Access Point. When omnidirectional transmissions are used at the Mobile Stations, the asynchronous nature of the 802.11 MAC handshake structurally limits the possibility to exploit spatial reuse. Significant throughput enhancements can be achieved only at the expense of redesigning (part of) the 802.11 MAC protocol: mainly a form of synchronizat…
A CAPWAP-Compliant Solution for Radio Resource Management in Large-Scale 802.11 WLAN
2007
Recently, the impressive success of the IEEE 802.11 WLAN technology has dramatically changed the role of the wireless connectivity provisioning. Born as a wireless extension of small office or home networks, todays the WLANs are getting more and more popular as a large, even metropolitan, area networks. The deployment of large-scale WLANs has some critical issues, because of the lack of coordinated management functionalities among the network nodes. In this paper we briefly describe the CAPWAP architectural solution, for centralizing some control and maintenance functionalities in large scale WLAN, by guaranteeing the interoperability between network nodes provided by different vendors. We …
A CAPWAP Architecture for Automatic Frequency Planning in WLAN
2007
Recently, the impressive success of the IEEE 802.11 WLAN technology has dramatically changed the role of the wireless connectivity provisioning. Born as a wireless extension of small office or home networks, todays the WLANs are getting more and more popular as a large, even metropolitan, area networks. The deployment of large-scale WLANs has some critical issues, because of the lack of coordinated management functionalities among the network nodes. In this paper we briefly describe the CAPWAP architectural solution, for centralizing some control and maintenance functionalities in large scale WLAN, by guaranteeing the interoperability between network nodes provided by different vendors. We …
A Low-level Simulation Study of Prioritization in IEEE 802.11e Contention-based Networks
2006
This work deals with the performance evaluation of the IEEE 802.11e EDCA proposal for service prioritization in Wireless LANs. A large amount of study has been carried out in the scientific community to evaluate the performance of the EDCA proposal, mainly in terms of throughput and access delay differentiation. However, we argue that further performance insights are needed in order to fully understand the principles behind the EDCA prioritization mechanisms. To this purpose, rather than limit our investigation on throughput and delay performance figures, we take a closer look to their operation also in terms of low-level performance metrics (such as probability of accessing specific channe…
Measurement and Modeling of the Origins of Starvation in Congestion Controlled Mesh Networks
2008
Significant progress has been made in understanding the behavior of TCP and congestion-controlled traffic over multi- hop wireless networks. Despite these advances, however, no prior work identified severe throughput imbalances in the basic scenario of mesh networks, in which one-hop flows contend with two-hop flows for gateway access. In this paper, we demonstrate via real network measurements, test-bed experiments, and an analytical model that starvation exists in such a scenario, i.e., the one-hop flow receives most of the bandwidth while the two- hop flow starves. Our analytical model yields a solution consisting of a simple contention window policy that can be implemented via mechanism…
Performance Analysis in Spatially Correlated IEEE 802.11 Networks
2012
Wireless mesh networks are difficult to be characterized, especially under multi-hop traffic streams. The problem is that the local view of the channel and the correlation between the buffers of consecutive nodes in a stream path make complicated the identification of the contention level perceived by each station along the time. Such a figure is used in the models based on the so called decoupling assumption for evaluating the final scheduling of simultaneous channel access grants. In this paper we propose a simplified mesh network model focused on capturing the correlation due to the network topology and traffic routes rather than the access protocol state at each node. To this purpose, w…
Performance analysis of the out-of-band signaling scheme for high speed wireless LANs
2005
In this paper, we study the performance of our earlier proposed out-of-band signaling (OBS) scheme for high speed wireless local area networks (WLANs). We employ the system approximation technique for modeling of the OBS scheme. An equivalent state dependent single server queue, that describes the OBS scheme, is constructed for the analysis of the throughput and delay performances. Moreover, we study the throughput optimization of the OBS scheme, which provides a means for optimizing the performance of the OBS scheme, given a particular network environment. Finally, we conduct several simulation experiments to validate our analytical results.
Performance evaluation of differentiated access mechanisms effectiveness in 802.11 networks
2005
The IEEE 802.11e draft specification aims to extend the original 802.11 MAC protocol by introducing priority mechanisms able to manage bandwidth and resource allocation according to the QoS needs of real-time applications. Different strategies based on MAC parameter diversifications, such as contention window limits, contention window updating factor and silence monitoring time, can be pursued in order to provide service differentiation, also in the case of distributed access. In this paper, we investigate on the behaviour of each differentiation possibility under different load conditions and traffic requirements. Our results show that the most powerful mechanisms which provide service dif…
Flexible and Modular Support for Multicast Rate Adaptation in WLANs
2013
The flexibility and virtualization capabilities provided by wireless cards have received significant attention as a means to reduce development costs. In this paper we present a modular architecture that exploits the features provided by emerging PHY and MAC implementations to rapidly develop new rate adaptation algorithms for multicast trans- mission in wireless LANs. We validate our solution by developing three rate adapta- tion algorithms that use an innovative sensing mechanism to evaluate the frame recep- tion correlation of the members of the multicast group. The experimental results obtained on a real-life testbed show that our solutions permit to increase the performance of multicas…
An Improved Receiver Architecture for Cyclic-Prefixed OFDM
2009
A novel Orthogonal Frequency Division Multiplexing receiver architecture to be employed with standard (e.g. Wireless LAN) transmitters is proposed. It features enhanced error-rate performance with flexible computational complexity and robustness to imperfect channel estimation. It is based on exploitation of the redundancy available in the cyclic prefix after cancellation of interference from the previous block. In order to show the effectiveness of our proposal, a number of comparisons to the standard per-subcarrier receiver and a previously existing method are reported.