Search results for "ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS"

showing 10 items of 449 documents

Adaptive Contention Resolution for VoIP Services in the IEEE 802.16 Networks

2007

In the IEEE 802.16 networks, a subscriber station can use the contention slots to send bandwidth requests to the base station. The contention resolution mechanism is controlled by the backoff start/end values and a number of the request transmission opportunities. These parameters are set by the base station and are announced to subscriber stations in the management messages. In the case of the VoIP services, it is critical that the contention resolution occurs within the specified time interval to meet the VoIP QoS requirements. Thus, it is the responsibility of the base station to set correct contention resolution parameters to ensure the QoS requirements. This paper presents analytical c…

IEEE 802Voice over IPCorrectnessbusiness.industryComputer scienceQuality of serviceComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKSReal-time computingWiMAXBase stationBandwidth (computing)businessResource management (computing)Computer network2007 IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks
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Analysis of the Non-Transparent In-Band Relays in the IEEE 802.16 Multi-Hop System

2010

This paper presents extensive dynamic simulations of the non-transparent in-band relays working in the distributed scheduling mode. The simulation results show that in-band relays can improve noticeably the spectral efficiency without acquiring an additional radio spectrum. Also, packet transmission delays become smaller. An important outcome of the dynamic simulations is that it is very crucial to choose a correct relay zone size where the base station and relay nodes exchange data. Otherwise, throughput fairness of the whole system declines. It indicates an importance of the relay zone size adjustment algorithm that the base station must run.

IEEE 802business.industryComputer scienceAutomatic repeat requestComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKSThroughputSpectral efficiencyWiMAXRadio spectrumScheduling (computing)law.inventionBase stationRelaylawComputer Science::Networking and Internet ArchitecturebusinessComputer Science::Information TheoryComputer network2010 IEEE Wireless Communication and Networking Conference
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ARQ parameters for VoIP in IEEE 802.16 networks

2009

IEEE 802.16 standard defines two data retransmission mechanisms. HARQ provides fast retransmissions in cost of slightly increased overhead. On the contrary, ARQ has less overhead in cost of bit longer delays. It is therefore often used with BE connections. In addition to delay tolerant applications, BE can also be used for real-time services. Therefore, in this paper we analyze the ARQ mechanism and provide guidelines on how to set the ARQ parameters to achieve a good balance between the VoIP delay and packet loss.

IEEE 802business.industryComputer scienceAutomatic repeat requestQuality of serviceRetransmissionComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKSHybrid automatic repeat requestData_CODINGANDINFORMATIONTHEORYSelective Repeat ARQPacket lossOverhead (computing)businessComputer network2009 Wireless Telecommunications Symposium
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Adaptive contention resolution parameters for the IEEE 802.16 networks

2007

In the IEEE 802.16 networks, the base station allocates resources to subscriber stations based on their QoS requirements and bandwidth request sizes. A subscriber station can send a bandwidth request when it has an uplink grant allocated by the base station or by taking part in the contention resolution mechanism. This paper presents analytical calculations for parameters that control the contention resolution process in the IEEE 802.16 networks. In particular, the backoff start/end values and the number of request transmission opportunities are considered. The simulation results confirm the correctness of theoretical calculations. They also reveal that the adaptive parameter tuning results…

IEEE 802business.industryComputer scienceQuality of serviceComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKSReal-time computingThroughputStationBase stationTransmission (telecommunications)Telecommunications linkBandwidth (computing)businessComputer networkThe Fourth International Conference on Heterogeneous Networking for Quality, Reliability, Security and Robustness & Workshops
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Impact of portable device restrictions on IEEE 802.16 performance

2008

IEEE 802.16 is a good alternative for fast wireless connection in the next generation portable information devices (PID). However it was not originally designed for portable devices, but mobility was added later to the specification. This means that the lack of resources on portable devices might have a significant impact on which IEEE 802.16 features should be chosen and how they should be used. Proper usage of ARQ can increase the IEEE 802.16 performance but it can also require much resources from PIDs. In this paper we focus on how ARQ features are affected by limited resources on PID and how much the limitations affect on the performance.

IEEE 802business.industryWireless networkComputer scienceBroadband networksAutomatic repeat requestComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKSComputerApplications_COMPUTERSINOTHERSYSTEMSWiMAXBase stationEmbedded systemWirelessMobile telephonybusinessComputer networkPORTABLE-POLYTRONIC 2008 - 2nd IEEE International Interdisciplinary Conference on Portable Information Devices and the 2008 7th IEEE Conference on Polymers and Adhesives in Microelectronics and Photonics
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Rethinking the IEEE 802.11e EDCA Performance Modeling Methodology

2010

Analytical modeling of the 802.11e enhanced distributed channel access (EDCA) mechanism is today a fairly mature research area, considering the very large number of papers that have appeared in the literature. However, most work in this area models the EDCA operation through per-slot statistics, namely probability of transmission and collisions referred to "slots." In so doing, they still share a methodology originally proposed for the 802.11 Distributed Coordination Function (DCF), although they do extend it by considering differentiated transmission/ collision probabilities over different slots.We aim to show that it is possible to devise 802.11e models that do not rely on per-slot statis…

IEEE 802medium access protocolSettore ING-INF/03 - TelecomunicazioniComputer Networks and Communicationsbusiness.industryComputer scienceWiFiDistributed computingQuality of serviceComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKSQoSThroughputDistributed coordination functionComputer Science ApplicationsTransmission (telecommunications)Wireless lanElectrical and Electronic EngineeringbusinessThroughput (business)SoftwareComputer networkCommunication channelIEEE/ACM Transactions on Networking
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Analysis of the limitations of WiFi communications managed by the IEEE 802.11 protocol in data transmission in automated power distribution systems

2010

This paper presents a study on the performances of the IEEE 802.11 protocol used in a Medium Voltage networks management system, carried out using a model for the simulation of WiFi chains architectures. The results of the simulations give some practical indications for the use of the IEEE 802.11 protocol also in presence of transmissions characterized by rigid time intervals, for which this protocol is usually not suitable. Finally the whole communications system is presented.

IEEE 802.11EngineeringIEEE 802IEEE 802.11uSettore ING-INF/03 - Telecomunicazionibusiness.industryInter-Access Point ProtocolWiFiComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKSSettore ING-IND/33 - Sistemi Elettrici Per L'EnergiaIEEE 802.1QEmbedded systemIEEE 802.11g-2003DiagnosticIEEE 802.1XbusinessComputer networkIEEE 802.11sIEEE 802.11r-2008SPEEDAM 2010
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Enabling a win-win coexistence mechanism for WiFi and LTE in unlicensed bands

2018

The problem of WiFi and LTE coexistence has been significantly debated in the last years, with the emergence of LTE extensions enabling the utilization of unlicensed spectrum for carrier aggregation. Since the two technologies employ com-pletely different access protocols and frame transmission times, supporting coexistence with minimal modifications on existing protocols is not an easy task. Current solutions are often based on LTE unilateral adaptations, being LTE in unlicensed bands still under definition. In this paper, we demonstrate that it is possible to avoid a subordinated role for WiFi nodes, by simply equipping WiFi nodes with a sensing mechanism based on adaptive tunings of the …

IEEE 802.11Information Systems and ManagementUnlicensed bandbusiness.industryComputer scienceWiFiComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS05 social sciencesMechanism based050801 communication & media studies020206 networking & telecommunications02 engineering and technologySpectrum managementScheduling (computing)Win-win game0508 media and communicationsIEEE 802.11Computer Networks and CommunicationWhite spaces0202 electrical engineering electronic engineering information engineeringLTE-UbusinessComputer networkISM coexistency
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Assessing the effectiveness of IEEE 802.11e in multi-hop mobile network environments

2004

The IEEE 802.11e technology is receiving much interest due to the promising enhancements it offers to wireless local area networks in terms of QoS support. Until now, research has focused on single hop, access point based environments, which are the most common. We review the enhancements proposed in the last IEEE 802.11e draft (version 8.0). We analyze the performance of the IEEE 802.11e protocol on ad-hoc networks (multi-hop) in terms of throughput and end-to-end delay. We also measure the effectiveness for static and fully dynamic networks with a variable number of source stations. Finally, we analyze the performance of IEEE 802.11e when legacy IEEE 802.11 stations (no IEEE 802.11e suppo…

IEEE 802.11uIEEE 802IEEE 802.11w-2009business.industryComputer scienceInter-Access Point ProtocolDistributed computingComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKSIEEE 802.11b-1999IEEE 802.1XbusinessIEEE 802.11sComputer networkIEEE 802.11r-2008
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QoS Support for Time-Constrained Multimedia Communications in IEEE 802.11 WLANs: A Performance Evaluation

2005

During the past few years, we have been witnessing the massive deployment of IEEE 802.11 wireless LANs. Even though the widespread deployment of such wireless LANs, many studies are still underway aiming to design and develop simple yet effective QoS mechanisms for supporting time-constrained services over such platforms. In this paper, we first overview five different QoS mechanisms recently introduced in the literature as well as the upcoming IEEE 802.11e (EDCA) standard. We then carry out a comparative performance evaluation of all the QoS mechanisms. We focus our study on the effectiveness of the various QoS mechanisms for supporting time-constrained services.

IEEE 802.11uIEEE 802IEEE 802.11w-2009business.industryInter-Access Point ProtocolComputer scienceComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKSWireless Multimedia ExtensionsMobile QoSIEEE 802.11e-2005businessTelecommunicationsComputer networkIEEE 802.11r-20082005 Systems Communications (ICW'05, ICHSN'05, ICMCS'05, SENET'05)
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