What is the process of GSM communication?

ETSI's specifications on GSM mainly include: GSM48, GSM88 and GSM92.

Chapter 1 Signaling Analysis of Call Process

For a call between mobile users, the signaling process can be divided into three relatively independent parts: 8? 5 calling mobile subscriber part 8? 5 called mobile subscriber part 8? 5 disconnection part

Summary

This lesson mainly describes the signaling flow of the call process of mobile users, including mobile calling, mobile called and tandem call. You should be able to master the signaling process of various calling processes, such as mobile calling fixed users, fixed users calling mobile users, and tandem calling process of TMSC. You should have a certain understanding of various abnormal processes, especially the release process of resources.

chapter 2 authentication

summary

this lesson mainly describes the authentication process. Authentication is one of the important characteristics that distinguish digital networks from analog networks. Through authentication, the system can provide services for legal users and refuse services for illegal users. Through the study of this lesson, we mainly understand the principle of authentication, the role of authentication center and the basis for the system to judge illegal users.

chapter 3 location update

summary

this lesson introduces the related content of location update. After studying this lesson, you should master the reason, classification and main process of location update. Make clear the difference between location update and switching.

Chapter 4 Handover

4.1 Reasons for handover:

(1) Wireless standard 8? 5 signal quality 8? 5 field strength MS and/or /BTS receiving level 8? 5 ms-BTS distance 8? 5. Improve interference and power control (select cells to be switched under the condition of ensuring normal communication quality to minimize MS transmission power and improve interference)

(2) Network standard 8? 5 4.2 handover initiation mode

(1) BSC detects the reason of wireless transmission according to management standard and executes handover decision

(2) MSC asks handover candidate

4.3 handover type

(1) internal handover

(2) external handover (MSC participates in controlling handover process) 8? 54.4 control flow (taking the "handover request indication" initiated by BSS as an example)

4.4.1 handover with MSC base stations

4.4.2 handover between base stations of different MSCS in PLMN

4.4.3 inter-office handover processing

Summary

This lesson introduces the relevant contents of handover. After learning this lesson, you should master the causes and classification of switching, and have a certain understanding of the entities involved in various switching and the role of each entity in switching.

chapter 5 short message flow

5.1 basic flow of mobile originating short messages

for mobile phones, mobile originating short messages and mobile terminating short messages are two completely independent processes, and the mobile originating short messages start from the mobile phone access system until they are successfully sent from the short message center. The mobile phone sends the short message to VMSC, and VMSC submits the short message to IWMSC according to the identification number of the short message center carried in the short message, and IWMSC submits the short message to the short message center.

mobile originating short messages can be divided into the following processes: 8? 5 Access and authentication encryption 8? 5 send a short message to the short message center 8? The short message center reports the sending result to the mobile phone.

The process of access, authentication and encryption is consistent with the corresponding process of mobile user calling. The following figure is the flow chart of mobile originating short messages.

5.2 basic flow of mobile terminal short message

5.3 short message case

Summary

This lesson describes the basic flow of short message, and users of short message network, GSM network and PSTN network provide services at the same time. Learning this section, you should basically master the process of short messages.

Chapter 6 Call Reconstruction and Directional Retry Flow

6.1 Basic Flow of Call Reconstruction

6.2 Basic Flow of Directional Retry

Summary

This lesson describes the basic principles and signaling flow of call reconstruction and directional retry. Call reestablishment and directional retry can reduce the dropped call rate and improve the quality of service. Learning this course, you should basically master the significance of call re-establishment and directional retry and the basic signaling process.