133 research outputs found
Downlink Scheduling in 3GPP Long Term Evolution (LTE)
No full textLTE is the evolution of the Universal Mobile Telecommunications System (UMTS). A scheduler assigns the shared resources (time and frequency) among users terminals. I have examined the impact of different scheduling schemes on the throughput and I also have investigated the fairness of each scheduling scheme. The main contribution of this thesis is to propose a new scheduling algorithm that can be comprise between the throughput and the fairness.TelecommunicationsElectrical Engineering, Mathematics and Computer Scienc
Device-to-Device Communications Underlaying a Cellular Network
No full textMobile voice service is already considered a necessity by many, and mobile data, video, and TV services are now becoming an essential part of consumers' lives. The number of mobile subscribers is growing rapidly and bandwidth demand due to data and video services is increasing. There is a need for capacity to increase in order for mobile broadband, data access, and video services to engage the end consumer. Device-to-device (D2D) communications underlaying cellular networks entails the ability of a cellular network to allow devices to communicate directly with each other in the operating (licensed) spectrum of the cellular network. With the application of specific rules and strategies, D2D communications offloads the mobile network and increases the spectral efficiency. In this thesis we developed a method for the application of D2D communication, controlled by a cellular network. By deriving the theoretical upper bound on the interference we have analytically derived equations describing the minimum distances to be maintained between simultaneously operating links, to achieve a given minimum SINR. We devised a strategy to group and schedule links which fulfill these minimum requirements, so that multiple links may operate simultaneously. We describe a power optimization method to minimize the number of groups to further improve the efficiency of the occupation of resources. Finally we performed simulations for various D2D scenarios, including a scenario representing a realistic urban environment, to illustrate the potential of this grouping and scheduling strategy.Wireless and Mobile CommunicationsElectrical Engineering, Mathematics and Computer Scienc
Electron-Density Fluctuation in Jet Measured with Multichannel Reflectometry
No full textElectron density fluctuations have been studied with the multichannel reflectometer at JET. Results from three topics are presented: the location of MI-ID modes, fluctuations during the sawtooth crash and fluctuations before and after the L-mode to H-mode transition. The nonlinear response of the homodyne detection system, used to measure density fluctuations is considered. This can introduce artefacts in the data which should be taken into account in the interpretation of the signals
Integrating TETRA with Wireless Mesh Networks
No full textTerrestrial Trunked Radio(TETRA) is a narrow band digital cellular network for Private Mobile Radio (PMR) communications mainly designed for voice communications with limited packet data capability because of band-width limitations. This limited packet data capability of TETRA is used for the integration of the TETRA network with wireless mesh networks. The wireless mesh network used in this thesis work is part of the FIGO network. FIGO is a robust communication system mainly intended for public safety communications and it consists two main network parts. One of these parts is the wireless adhoc network which can be deployed on incident areas. The oher one is the infrastructure omponent (back office node) that is used to nterlink disconnected adhoc nodes and it can also offer access for controlling an incident in the adhoc network. The FIGO network uses different communication technologies to link the adhoc network with the back office node and the main aim of this thesis work is to integrate the TETRA network with the FIGO network so that the TETRA can be used as one of the links from the adhoc network to the back offie node of the FIGO network. The main problem of the TETRA-FIGO integration is that the wireless adhoc network generates a lot of control signals that can easily overload the narrowband packet data channel of the of the TETRA network. In addition to the control overheads, the excessive headers also contribute a lot of overheads to the narrowband TETRA channel. Two architectures are proposed in thesis report to integrate TETRA with the FIGO network and the performance of these two new proposed architectures is analyzed and compared with the existing FIGO network protocols in terms of control traffic and header overheads.WMCTelecommunicationsElectrical Engineering, Mathematics and Computer Scienc
Interpretation of heat and density pulse measurements in JET in terms of coupled transport
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