Calculate the latitude and longitude of constellation with stk

Cell ID, that is, the cell number where the wireless network reports the terminal (estimated by the service base station), and the location service platform translates the cell number into latitude and longitude coordinates. This method is simple to implement, does not need to add equipment on the wireless access network side, and has little change to the network structure. The disadvantage is that the positioning accuracy is low, which can generally reach 300-500m in the urban area and several kilometers in the suburbs. The cell number will be obtained in the following scenarios: 1, cell routing paging 2, location area update 3, cell update 4, URA update 5 and routing area update.

The cell coverage information can be identified by the cell ID, the serving cell ID or the geographic coordinates of the serving cell. The estimated location of the UE may be a fixed location of the serving cell (such as the location of the base station) or other fixed locations of the coverage area of the serving cell. Geographical coordinates can be obtained in combination with other information, such as round-trip time straight line RTT of FDD or Rx time deviation of TDD or UE advance time, but this enhancement technology is described in another chapter.

The network elements involved in Cell ID location include: location application, location gateway (GMLC of 3GPP and MPC of 3GPP2), MSC, HLR, SRNC (including SAS), NodeB and UE. Let's explain the most typical process:

1) User U 1 sends a request to the application, and the application sends this request to GMLC, which authenticates the application; After the application authentication is passed, GMLC authenticates the user A 1 who initiated the positioning; After passing the authentication, GMLC authenticates the target user U2 and checks the privacy rights of U2.

2) If the target user U2 allows positioning, GMLC requests the destination information of the target user from the HLR to which U2 belongs;

3) HLR gives gives the current access information of U2;

4) GMLC sends a location request to MSC/SGSN according to the visit information, requesting to locate user U2;

5) MSC/SGSN locates user A2. If necessary, MSC/SGSN can initiate paging to terminal U2 to update its cell.

6) After positioning, MSC/SGSN returns the location information of user U2 to GMLC;

7) GMLC returns the location information of user A2 to the application, and the application uses this information to report the requested geographic location information to user U 1 in combination with GIS.

There are three ways to realize the application of Cell ID location, including network-based way and terminal-based way:

1 based on network mode 1: GSM 03.7 1 protocol mode;

2. Mode 2 based on network: adopting MAP ATI signaling and following 3GPP TS 09.02；;

Based on terminal STK mode.