Basic knowledge of road loss of 3GPP channel model

Some main abbreviations about channel model ：

LOS：Line Of Sight

NLOS：Non-LOS

O2I：Outdoor-to-Indoor

O2O：Outdoor-to-Outdoor

RMa：Rural Macro

SCM：Spatial Channel Model

SSCM：Statistical Spatial Channel Model

UMa：Urban Macro

UMi：Urban Micro

InF：Indoor Factory

InH：Indoor Hotspot

IRR：Infrared Reflecting

ISD：Intersite Distance

Typical scenarios about channel models ：

1. UMi (Street canyon, open area) with O2O and O2I: The base station is on the top of the building , There are open areas around ( The width is 50 M to 100 Rice or so ). Height of transmitting end 10 rice , Height of receiving end 1.5 to 2.5 rice , Station spacing 200 rice .(Tx height:10m, Rx height: 1.5-2.5 m, ISD: 200m)
2. UMa with O2O and O2I： With the front UMi similar , The difference lies in the height of the transmitting end and the distance between stations .(Tx height:25m, Rx height: 1.5-2.5 m, ISD: 500m). You can see UMa It belongs to a scene with a larger coverage .
3. Indoor： Indoor coverage scene , Such as offices and shopping malls . The base station is deployed on the roof , The height of the transmitting end is 2 To 3 rice , Height of receiving end 1.5 rice , The coverage of the base station is about 500 Square meters .(Tx height: 2-3m, Rx height: 1.5m, area: 500)

On the calculation of road loss of channel model ：

The channel model gives the road loss value of the terminal at different positions from the base station . among , If there is no shelter between the terminal and the base station , You need to use LOS Model . If there is obstruction between the terminal and the base station , Just use NLOS Model . If the terminal is indoors , And access to the outdoor macro station , Then we need to consider O2I Penetration loss of .

stay TR38.901 chart 7.4.1 in , The height of the base station and the terminal and the distance between the base station and the terminal are defined .

With UMa Take the scene ,TR38.901 Table 7.4.1-1 in , What is given Pathloss The formula is ： 

You can see from the above formula that , stay UMa LOS scenario ,Pathloss Height with base station 、 Terminal height 、 Carrier frequency 、 The distance between the terminal and the base station is related .

If the terminal is indoors , When connecting to the outdoor macro station , The channel model also needs to consider O2I Penetration loss of .

TR 38.901 Chinese formula 7.4-2 given O2I In the scene Pathloss computing method .

  among ,

PLb It is the basic road loss introduced above ;

PLtw Is the penetration loss of the wall ;

PLin It is the road damage after passing through the wall ;

TR 38.901 Chinese formula 7.4-3 given PLtw The calculation method of ：

among ,

PLnpi It is an additional loss considering the non vertical incidence angle , Is a fixed value ;

Pi It is the cost proportion of different materials ;

Lmaterial_i Is the penetration loss parameter of the material ;

It can be seen from the above formula that , The penetration loss is strongly related to the material . stay TR 38.901 Table 7.4.3-1 in , The loss parameters of different materials are given . among , The glass with infrared reflection material has the largest penetration loss .

TR38.901 Table7.4.3-2 in , An example is given , For low road loss scenarios , It can be seen that cement accounts for more walls . For high road loss scenarios , The wall with infrared reflective glass accounts for more .

 

The above content is only a preliminary introduction to the basis of channel model road loss calculation , For details, please refer to 3GPP TR 38.901.