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Msc dissertation presentation
 

Msc dissertation presentation

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The document contains my MSc viva slides on Downlink Performance of Base station Cellular Systems using Beamforming Techniques

The document contains my MSc viva slides on Downlink Performance of Base station Cellular Systems using Beamforming Techniques

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    Msc dissertation presentation Msc dissertation presentation Presentation Transcript

    • Downlink Performance of Cooperative Base Station Cellular Systems using Beamforming Techniques An Msc Dissertation Presentation by Chinaemerem Nwankwo Downlink Performance of Base station Cellular Systems using Beamforming Techniques31/12/2011 1
    • Introduction/ Objectives of the Dissertation• To investigate the downlink performance of cellular systems under combined Cooperative Multipoint with Beamforming Strategy.• To investigate and evaluate the energy and spectral efficiency trade-off of cellular systems under Coordinated MultiPoint (CoMP).• To identify the trade-off between the performance improvement and the extra energy needed due to CoMP. Downlink Performance of Base station 31/12/2011 Cellular Systems using Beamforming 2 Techniques
    • Conventional Cellular System• This is otherwise known as Figure 1: A Convention Cellular Network showing the desired signals in bold lines and the interfering the Single Cell beamforming signals in dotted lines system• A conventional system is designed such that that each BS serves associated mobile terminals independently and experiences interference from neighbouring cells Downlink Performance of Base station31/12/2011 Cellular Systems using Beamforming 3 Techniques
    • Base Station Cooperation and Coordination Figure 2: Cells showing Coordinated Multipoint technology where all signals from the different• Inter-site CoMP cells are useful signals• Intra-site CoMP• CoMP-BF• CoMP-JP Downlink Performance of Base station31/12/2011 Cellular Systems using Beamforming 4 Techniques
    • Coordinated MultiPoint Technology Figure 3: Downlink CoMP transmission showing the• CoMP-BF forms of joint processing : a) Joint transmission; b) Dynamic cell selection; c) Coordinated beamformingo Data only available at the serving cell• CoMP-JPo Data is available in the cooperating set -Joint transmission -Dynamic cell selection Downlink Performance of Base station31/12/2011 Cellular Systems using Beamforming 5 Techniques
    • Why Cooperation and Coordination• Improved capabilities of • Improved network mobile devices performance, especially to edge users• Improved capacity of the cellular network • Energy efficiency/conservation • Spectral efficiency Downlink Performance of Base station31/12/2011 Cellular Systems using Beamforming 6 Techniques
    • System Model and Problem Formulation• Downlink system model• This is formulated as:Minimise total transmitted power of the base station antennaarraySubject to :the received signal power at the i-th mobile received interference + noise at i-th mobileis greater than a given threshold, ϒi Downlink Performance of Base station31/12/2011 Cellular Systems using Beamforming 7 Techniques
    • Algorithm based on SemidefiniteOptimisation• Downlink convex problems o Semidefinite can be solved either by: optimisation- here our constraint is SINR and we exploit the Uplink-o Power control based Downlink Duality in TDD algorithm – most suited for systems to obtain the beamforming problems on convex equation: the uplink where the Subject to: constraint is power Downlink Performance of Base station Cellular Systems using Beamforming31/12/2011 Techniques 8
    • Single cell Beamforming Implementation• The diagram shows a cell • Recall having 6 adjacent base stations Subject to For the single cell case, we translate the above equations to: s.t Downlink Performance of Base station Cellular Systems using Beamforming31/12/2011 Techniques 9
    • CBF ImplementationS.T:1.2. Downlink Performance of Base station Cellular Systems using Beamforming31/12/2011 Techniques 10
    • CoMP-JP ImplementationThe convex equation is given as:Subject toNotice that the system is now reduced to a ‘Network MIMO.’ Forour case, we have:Subject to:1.2. Downlink Performance of Base station Cellular Systems using Beamforming31/12/2011 11 Techniques
    • Performance Evaluation and Results Performance Evaluation and Results • We shall evaluateCellular Layout 10 cellsNumber of cooperating cells 2 the performance ofReuse factorMobile Noise Figure 1 7dB the cellular systemNumber of antenna elements per site 2 using theSINR requirements Voice= -30.5 dB, Video= -26.5dB, Data= -27dB parameters in theData rates Voice = 13kbps, video=32kbps, data= 28.8kbps table under theBandwidth 10MHz following scenariosInter-site Distance 500m -the single cell caseActive User Equipment per site 1 (except for the conventional case that has 2) -the CoMP-BFUE-Base station distance >= 50m -the CoMP-JP Downlink Performance of Base station 31/12/2011 Cellular Systems using Beamforming 12 Techniques
    • Conventional SystemAn illustration of a conventional The plot of Pmin vs mobile distance and azimuth angle of orientationbeamforming system showing theactive cell surrounded by 6 adjacentcells servicing 2 mobile users with onestationary and the other movingaround the cell area. Downlink Performance of Base station31/12/2011 Cellular Systems using Beamforming 13 Techniques
    • Cooperating Systems• In CBF, the transmission to a • For JP/JT, the single User is done from the transmission to a single serving cell. Scheduling is UE is simultaneously dynamically coordinated transmitted from between the cells in order to multiple transmission reduce the interference points, across cell sites. The multi-point between different transmissions will be transmissions. coordinated as a single transmitter with• See diagrams and graphs in antennas that are the next slide geographically separated Downlink Performance of Base station31/12/2011 Cellular Systems using Beamforming 14 Techniques
    • Cooperating Systems• The coordinated base station cellular system with 2 cooperating sets, each having 6 adjacent cells 30 60 90 0 Cell 4 120 Cell 5 Cell 3 Cell 6 Cell2150 Cell 10 Cell 1 Cell 9 Cell 7180 Cell 8 Downlink Performance of Base station Cellular Systems using Beamforming31/12/2011 15 Techniques
    • Non-cooperating and the Cooperating Schemes• The graph below shows the system performance as the mobile distance from the base station changes for the three schemes under consideration at constant SINR Downlink Performance of Base station31/12/2011 Cellular Systems using Beamforming 16 Techniques
    • Non-cooperating and the Cooperating Schemes• The graph below shows the system performance as the mobile azimuth angle of orientation from the base station changes for the three schemes under consideration at constant SINR.• Notice the behaviour of CBF and CJP Downlink Performance of Base station31/12/2011 Cellular Systems using Beamforming 17 Techniques
    • Non-cooperating Vs the Cooperating Schemes• As the quality of service requirement increases, CoMP triumphs more.• Notice from the next graph, that the difference in power requirements narrows as higher QoS is desired and CoMP-JP power requirement rises sharply Downlink Performance of Base station31/12/2011 Cellular Systems using Beamforming 18 Techniques
    • Cellular System Capacity Downlink Performance of Base station31/12/2011 Cellular Systems using Beamforming 19 Techniques
    • Evaluation of the System Capacity• The graph below shows the performance of the three schemes when several mobile applications of different throughput are considered.• The best performance is realised using CoMP-JP, which narrows with respect to CBF as the throughput increases Downlink Performance of Base station31/12/2011 Cellular Systems using Beamforming 20 Techniques
    • CONCLUSION• CBF Vs CoMP-JP• Performance of coordinated systems -At low SINR – CoMP-JP -At higher SINR – Similar performance -CBF mitigates interference -CoMP-JP can eliminate interference -both increases LTE transmission rates• Challenges of Coordinated Systems -extra equipment cost -extra overhead in terms of processing and backhaul forCoMP-JP Downlink Performance of Base station31/12/2011 Cellular Systems using Beamforming 21 Techniques
    • FUTURE WORK• Investigating the viability of implementing CoMP-JP be evaluating the extra energy cost required• Assuming a scenario where more base station in the cellular architecture are cooperating• Seek out and implementing a different path loss model. Downlink Performance of Base station Cellular Systems using Beamforming31/12/2011 22 Techniques
    • Thank you31/12/2011 24