System Level Modeling and Optimization of the LTE Downlink

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3. Physical Layer Modeling and LTE System Level SimulationTable 3.3.: Simulation parameters employed for the validation of the L2S model in the singlecell,single-user scenario.Frequency(2.14 GHz( ) 4π d f 3Pathloss [dB]max 10 log 10 , 0)cBandwidth1.4 MHzTX power, antenna5 W, omnidirectionallyNoise spectral density-160 dBm/HzChannel model ITU-R Pedestrian-A [97], block fadingChannel knowledgePerfectFeedback delaynoneNumber of eNodeBs 1Number of UEs 1y pos [m]4003002001000−100−200−300−400ROI SNR [dB]−300 −100 100 300x pos [m]20151050−5distance [m]45040035030025020015010050SNR vs. distance to eNodeB0−10 0 10 20 30 40SNR [dB]Figure 3.15: Left: SNR map over the simulated ROI (color scale limited to a [-5,20] dB SNRrange). Right: Relation between the distance from the eNodeB site and thepost-FFT SNR. Simulation parameters listed in Table 3.3.level simulator [78], which implements the PHY layer abstraction models presentedin Chapter 3. As performance measure, throughput has been chosen, as it is ultimatelythe metric of interest.The following transmit modes defined in [39], as well as antenna configurations, havebeen evaluated, in all cases under a Ped-A channel at 5 km/h:ˆ Single transmit antenna (mode 1): 1 × 1 (SISO), 1 × 2 (SIMO).ˆ Transmit Diversity (mode 2): 2×2.ˆ Open Loop Spatial Multiplexing (mode 3): 2×2, 4×2, 4×4.ˆ Closed Loop Spatial Multiplexing (mode 4): 2×2, 4×2, 4×4.For all of the listed configurations, link level and system level results are shownin Figures 3.16 and 3.17. For the SNR range between -10 and 40 dB, each plot44
3. Physical Layer Modeling and LTE System Level Simulationdepicts throughput results for each of the four transmit modes considered: (i) singletransmit antenna, (ii) TxD, (iii) OLSM, and (iv) CLSM. System level results (solidline) are plotted overlapped to link level ones (dashed line).6655throughput [Mbit/s]4321x2 MRC (link level)11x2 MRC (system level)SISO (link level)SISO (system level)0−10 0 10 20 30 40SNR [dB]throughput [Mbit/s]4321TxD 2x2 (link level)0−10 0TxD 2x2 (system level)10 20 30 40SNR [dB]Figure 3.16: Link level and system level simulation results, single cell scenario. Left: Singleantenna transmit mode (SISO and 1×2 with MRC). Right: TxD transmitmode (2×2).throughput [Mbit/s]20OLSM 2x2 4x4 (link level)18OLSM 2x2 4x4 (system level)OLSM 4x2 (link level)16OLSM 4x2 (system level)14OLSM 4x4 2x2 (link level)OLSM 4x4 2x2 (system level)121086420−10 0 10 20SNR [dB]30 40throughput [Mbit/s]2018161412CLSM 4x4 (link level)CLSM 4x4 (system level)CLSM 4x2 (link level)CLSM 4x2 (system level)CLSM 2x2 (link level)CLSM 2x2 (system level)1086420−10 0 10 20SNR [dB]30 40Figure 3.17: Link level and system level simulation results, single cell scenario. Left: OLSMtransmit mode (2×2, 4×2, and 4×4). Right: CLSM transmit mode (2×2, 4×2,and 4×4).As observed from the results in Figures 3.16 and 3.17, the results of the link abstractionmodel can be considered accurate with some deviation in the four-transmitantenna configuration of OLSM. As explained in Section 3.1.1.2, the block fadingassumption is actually not valid for the OLSM case, but a reduced-complexity approximationis employed so as to still be able to calculate a single value per TTI.As expected, accuracy is highest for the two transmit antenna case, where only oneprecoder is employed. From the observed results, it is concluded that for the highSNR regime, the 4×2 OLSM link abstraction should not be employed, as significantdeviations are present due to the inconsistency of the block fading assumption.45
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DissertationSystem Level Modeling a
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I hereby certify that the work repo
Page 9: KurzfassungDie vorliegende Arbeit p
Page 13 and 14: ContentsContents1 Motivation and Sc
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Page 17 and 18: 1. Motivation and Scope of Work1. M
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Page 23 and 24: BibliographyThe combined throughput
Page 25 and 26: 2. 3GPP Long Term Evolution2. 3GPP
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C. Taylor Expansion of the ZF MSEAp
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D. Evaluation of Multi-User GainD.
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D. Evaluation of Multi-User GainAvg
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Abbreviations and AcronymsAbbreviat
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Abbreviations and AcronymsKPILLRL2S
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Abbreviations and AcronymsU-PlaneUT
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Abbreviations and AcronymsBibliogra
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Abbreviations and Acronymsdescripti
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Abbreviations and Acronyms[69] Tech
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Abbreviations and Acronymsfemto cel
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