Millimeter-wave (Mm-w) is the trend of communication development in the future; users who carry mobile communication equipment could be blocked by others in a crowded population environment. Based on Shooting and Bouncing Ray (SBR) method and setting up different orientation receivers (RX), population density, and people fabric property at 28 GHz and 38 GHz, simulating experimental scene similar to station square by Wireless Insite software, we use least square method to do linear-regression analysis for path loss and build path loss model. The result shows that the path loss index has a certain change in the different frequency, orientation receivers, population density, and people fabric. The path loss index of RouteC1 and RouteA2 has an obvious change in the central transmitter (TX). Each route shadow fading obeys Gaussian distribution whose mean is 0. This paper’s result has a theoretical guiding for designing the communication system in a crowded population environment.
With the increase of smart phone users and the development of mobile APP, requirement for wireless data transmission rate is on daily increase. The frequency spectrum resource is very crowded in original; it cannot satisfy these requirements and is badly in need of new frequency spectrum to satisfy this one requirement. Now, Mm-w (30 GHz–300 GHz) starts to catch people’s eyes; more and more industry and application come to use Mm-w frequency. For some population quite dense areas like station, playground, and so on, human body is the one main blockage of influence signal transmission, and the different fabric could have some influences. When RX position and direction are different, path loss also has different change.
The effect of population density is the one key of radio wave propagation characteristics outdoor. The authors in [
This paper uses SBR as theoretical basis, to simulate the likeness station square by Wireless Insite and get the path loss. Modeling path loss by least square method is to obtain path loss model and shadow fading in different route.
We build simulation scene plans similar to station square, as shown in Figure
Simulation scene and human model.
Simulation scene
Human model
There are 5 TX in simulation scene; four corners have each one and center has one. Center TX1 has 6 receive routes, that is, RouteA1, RouteB1, RouteC1, RouteA2, RouteB2, and RouteC2; each route length is 180 m, starting from TX1 to 20 m; RouteA1, RouteC1, RouteA2, and RouteC2 horizontal angle are 30°. TX2, TX4 and TX3, TX5 receive route, respectively, are RouteD and RouteE in vertical direction; the length is 170 m; the other receive route is RouteA1, RouteC1, RouteA2, and RouteC2, respectively, in four corners. RX distance is 3 m in 8 receive routes; TX and RX antenna parameters are set as shown in Table
TX/RX parameters.
TX | RX | |
---|---|---|
High (m) | 30 | 1.5 |
Gain (dBi) | 21.6 | 0 |
Transmitted power (dBm) | 10 | — |
Type |
|
|
Polarization | Vertical polarization | Vertical polarization |
The simulated wave is set up sinusoid; the bandwidth is 1 GHz in 28 GHz and 38 GHz; each material property is shown in Table
Materials property parameters.
Materials | ɛ |
|
||
---|---|---|---|---|
28 GHz | 38 GHz | 28 GHz | 38 GHz | |
Skin | 10.7 | 10.05 | 7.32 | 10.25 |
Cotton | 1.7 | 1.56 | 0.038 | 0.12 |
Red leather | 2.15 | 2.04 | 0.14 | 0.23 |
Yellow leather | 2.3 | 2.12 | 0.09 | 0.067 |
Concrete | 6.23 | 6.20 | 0.2 | 0.22 |
Similarity to the station square simulation scene is shown in Figure
Similarity to the station square simulation scene.
Simplified path loss model formula is as follows:
According to receive route directivity, the receive routes RouteA1, RouteB1, RouteC1, RouteA2, RouteB2, and RouteC2 are selected in TX1, TX2, TX4, and TX3; TX5 receive route is RouteD and RouteE in vertical direction, respectively; TX2, TX3, TX4, and TX5 receive routes are RouteA1, RouteC1, RouteA2, and RouteC2, respectively.
That could obtain the path loss data of receive route RouteA1 in TX1 when population density is 0.01/m2 (human fabric is cotton) in 28 GHz by Wireless Insite, for getting
Scatter-fitting line in 28 GHz.
Each path loss index in 28 GHz TX1.
With the increase of population density, RouteA1, RouteB1, RouteC1, and RouteB2 path loss index all are decreased; RouteA2 and RouteC2 are increased; RouteC1 and RouteA2 path loss index
When
RouteC1 scatter-fitting line in 0.01/m2 TX4.
When
TX2, TX3, TX4, and TX5 each receive route
TX | TX2 | TX3 | TX4 | TX5 | ||||||||||||
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Route | RouteA1 | RouteD | RouteA2 | RouteE | RouteC1 | RouteD | RouteC2 | RouteE | ||||||||
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From Table
The simulation is similar to the method which, in 28 GHz, change in the frequency is 38 GHz; bandwidth still is 1 GHz; considering the human fabric is only cotton, simulating
Each path loss index in 38 GHz TX1.
Compared with 28 GHz, the path loss index
When
TX2, TX3, TX4, and TX5, located in four corners, are similar path loss index changing trend to 28 GHz; the only difference is that RouteA1 is increased with population density in TX2 and
RouteC1 scatter-fitting line in 0.1/m2 TX4.
Path loss model formula in TX4 where
Human fabric varies, leading to radio wave getting some change. In building simulation scene, the human fabric electromagnetic parameters set up cotton, red leather, and yellow leather, and they are distributed uniformly. When
Each receive route
28 GHz | 38 GHz | |||
---|---|---|---|---|
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| |
RouteA1 | 78.96 | 2.46 | 94.70 | 1.76 |
RouteB1 | 72.36 | 2.11 | 80.50 | 1.88 |
RouteC1 | 93.98 | 1.43 | 81.97 | 2.41 |
RouteA2 | 109.73 | 0.63 | 107.59 | 1.21 |
RouteB2 | 70.67 | 2.12 | 72.13 | 2.31 |
RouteC2 | 62.01 | 3.14 | 104.71 | 1.29 |
Compared with human wearing cotton fabric, in different receive orientations, path loss index has different change. At 28 GHz,
After linear-regression analysis on each route, we also need verification for shadow fading distribution characteristics. Considering human wear fabric variety, when
Empirical distribution and theories normal distribution.
For these routes’ shadow fading, use
Millimeter-wave is the trend for communication development in the future; in the crowded people environment, mobile communication equipment taken by users could be blocked by others. Based on SBR, to simulate experiment scene by Wireless Insite, it can get path loss and regression analysis through least square method and build path loss model. The result shows that the 6 receive routes of TX1, in the common conditions, RouteC1 and RouteA2, are opposite to others; when
The authors declare that there are no conflicts of interest regarding the publication of this paper.
This paper is supported by the Joint Funds of National Natural Science Foundation of China (U1504604) and supported by the Graduate’s Scientific Research Foundation of Zhengzhou University of Light Industry (2016045).