Microcell Urban Propagation Channel Analysis Using Measurement Data Mir Ghoraishi Jun-ichi Takada Tetsuro Imai Tokyo Institute of Technology NTT DoCoMo Inc. Takada Lab - TokyoTech 1
Urban Channel Models • Usually considers wall reflections, roof-top diffractions and building edge-diffractions as the major existing propagation micromechanisms. • For big macrocell scenarios gives a good approximation for the channel characteristics. • For smaller microcell scenarios in the dense areas may not be adequate. Takada Lab - TokyoTech 2
Propagation Prediction Tools • Ray tracing algorithms have been reported to have poor performances due to considering only simple propagation mechanisms e.g. specular reflections. • Existence of some objects like fences, signboards, etc. has caused severe degradation of these tools performances. Takada Lab - TokyoTech 3
Objective • To investigate propagation micro-mechanisms in urban areas. • To find the significant scatterers – reflectors. • To investigate objects (other than building walls) involving in propagation in urban areas. • Evaluate the effect of these objects and compare to the known mechanisms. Takada Lab - TokyoTech 4
Methodology • Performing a number measurements in the urban areas to clarify previously mentioned facts. • Obtaining the angular and temporal profile of the received power. • Distinguishing clusters by examining the azimuth-delay power profiles. • Identifying the probable corresponding scatterer to each cluster. Takada Lab - TokyoTech 5
Measurement • Small Cell • Low Height Antennas • Dense Urban Area • Line-of-Sight • AoA Analysis • Delay Analysis Takada Lab - TokyoTech 6
Measurement Process 60 m o 0 Rx Tx + o • constant speed 5 rpm • 10 directivity o rotation 3 • step rotation • 30 sec measurement in each step Takada Lab - TokyoTech 7
System Block Diagram Patch Array Rx o beamwidth 10 Tx Sidelobe -26dB trigger Data ATT Rx Recorder level Sleeve Antenna 3.35 GHz o Cesium PN-9 3 step Amp Oscillator Rotation 50 Mcps 10 W Tx Oscilloscope 5 rpm Controller Rotation Cesium (free run) Oscillator � Both receiver and transmitter Controller antennas are installed on the roof- tops of different car at the same height of 3 meters. Takada Lab - TokyoTech 8
Considerations • Only single-bounce reflections can be considered in the analysis, but still many scatterers can be identified. • The processing is not high resolution due to using directive antenna. There are space and time resolution limits. • Measurements were accomplished during midnights with little traffic in the streets. • Measurements were accomplished in February with no leaves on the trees. Takada Lab - TokyoTech 9
Location 1 (2 Points) Yokohama, Kannai, Kannaiodori 24 m Honmachidori St. 26 m N 50 m 10 m P2 47 m Tx P1 60 m 13 m P2 39 m Rx 16 m P1 Kannai Oodori Ave. 40 m 10 m 28 m 4 m 26 m Takada Lab - TokyoTech 10
Location 2 (3 Points) Yokohama, Kannai, Kaigandori Kaigandori St. N 18 m 85 m P3 P2 Tx 16 m P1 60 m P3 13 m Rx 98 m P2 P1 Bankokubashidori St. (30 m) Takada Lab - TokyoTech 11
Analysis Process (1) • Preparing the precise map of the measurement area, including every object located there. • Some building irregularities are Rx included, parked cars are not included. Takada Lab - TokyoTech 12
Analysis Process (2) • Griding the map according to the time zone ellipses and AoA Tx lines. • Only single-bounce reflected waves can be Rx analyzed. Takada Lab - TokyoTech 13
Analysis Process (3) • Conforming the azimuth-delay-power spectrum with the grid map of the environment. • There is power from inside building zones because of single- bounce assumption. Takada Lab - TokyoTech 14
Analysis (4) • The received power has a clustered pattern in space. • The clustered waves scattering sources can be estimated by this method. • Some clusters have been identified without any visible objects conformed. This can be due to multi-reflection effect. • Some objects were identified as scattering source. Takada Lab - TokyoTech 15
Example of Identified Objects (1) • Over roof-top signboard. Tx Rx Takada Lab - TokyoTech 16
Example of Identified Objects (2) 17 Tx Rx • A traffic sign. Takada Lab - TokyoTech
Identified Objects No. in No. in Identified Objects Description Location 1 Location 2 15 8 Signboard 7 14 Street light (Lamppost) 10 10 Traffic sign 10 2 Traffic light 0 3 Cable box 0 2 Vending machine 4 15 Others Takada Lab - TokyoTech 18
Received Power Contributions (LoS power is not considered in the analysis) With No Specular With Specular Wall Reflection Presented Wall Reflection Presented (Averaged Over 2 Scenarios) (Averaged Over 3 Scenarios) 11% 26% 31% 27% 19% 19% 24% 43% Scattering from Identified Objects Wall Reflection Multi-reflection Clustered Received Waves Not Clustered Received Waves Takada Lab - TokyoTech 19
Conclusions Typical metallic objects in the urban areas seem to have a significant effect in the propagation channel. It seems that in some situations, the objects have a stronger impact than the building’s wall surfaces with the same alignments and close distances. At least in some especial scenarios, by-object scattered waves can be dominant phenomenon in the propagation channel. Takada Lab - TokyoTech 20
21 Thank you very much ! Takada Lab - TokyoTech
Receiver Antenna Directivity 水 平 面 内 3 0 30 2 0 Antenna Gain (dB) 1 0 0 0 - 1 0 - 2 0 -30 - 3 0 - 4 0 - 1 8 0 - 1 2 0 - 6 0 0 0 6 0 1 2 0 1 8 0 -180 180 o 角 度 （ ° ） Angle of Arrival ( ) Takada Lab - TokyoTech 22
Data Acquisition ： 511 c h i p s D a t a L e n g t h 1 c h i p ： n sec 20 D e l a y P r o f i l e W i n d o w L e n g t h ： 10.22 μ sec Oscilloscope and data ： × 3000 recorder effects Observation Window : 30.66 msec D a t a r e c o r d e r s a m p l i n g r a t e s a m p l e ： 48000 /sec The number of samples in each delay profile ： 1472 samples Takada Lab - TokyoTech 23
Azimuth Power Profile L2 P1 Received Power -60 Received Power Ex LoS Normalized Power (dB) Received Power Ex IdOb Received Power Ex W -70 Received Power Ex Cl -80 -90 90 270 360 0 180 o DOA ( ) Takada Lab - TokyoTech 24
25 Normalized Power (dB) -125 -100 -115 -70 -80 -90 Power Distribution L1 L1 P2 Takada Lab - TokyoTech L2 P1
Sample PDP ° 0 - 1 0 - 2 0 - 3 0 ) m - 4 0 B d ( r - 5 0 e w - 6 0 o P - 7 0 - 8 0 30 samples Takada Lab - TokyoTech 26
Uncorrelated Fading Illuminated Area wall surface (or any other object) ° Rx beam ( ) 10 Tx Angular Spread ( ) AS t Rx beam point Χ ⎛ ⎞ = sin ; d Tx rotation route ρ Χ = π ϕ ∆ ϕ ⎜ ⎟ 2 sin Χ λ r r ⎝ ⎠ with diameter d t Takada Lab - TokyoTech 27
28 Map including Objects Rx Takada Lab - TokyoTech
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