5g NR PWS system

Implement a public alarm system , That is, the community broadcasting service （CBS：Cell Broadcast Service).

CBS Page by 82 Eight octets , Use the default character set , amount to 93 Characters . Other data encoding schemes can also be used . Up to... Can be connected to these pages 15 individual CBS news . Such kind CBS Each page of the message will have the same message identifier （ Indicates the source of the message ） And the same serial number . Use this information ,MS/UE Be able to recognize and ignore received messages .

CBS Messages are broadcast circularly by the cell according to the frequency and duration agreed by the information provider .CBS The frequency of repeated transmission of information will depend on the information it contains , for example , Dynamic information such as road traffic information may need to be transmitted more frequently than weather information . The repetition period will also be received by fast-moving high-speed mobile devices CBS The impact of messages on mobile phones . Receive if MS/UE Connected to the CS domain , It is not required MS/UE Of CBS The number of messages . If MS/UE Connected to the PS Domain and there is currently no data transfer , It should be able to receive messages .

4、5G The network is aimed at PWS Each has its own network architecture .

Community Broadcasting Center （CBC：cell broadcast centre） Is part of the core network , adopt SBc Reference point and MME Connected to a .

chart 2、3 and 4 It describes 5GS PWS The basic network structure of the architecture .

chart 2 It describes 5GS PWS System architecture , Use CBCF and AMF Service based interface between , Shows how network functions interact .

CBE The function of is not 3GPP Within the scope of the specification ; But suppose CBE be responsible for CBS All aspects of message formatting , Including the CBS The message is split into multiple pages .

CBC function ： stay 3GPP in ,CBC Be integrated into a node in the core network .

CBC Can be connected to multiple BSC/RNCs/MMEs/PWS IWF.CBC Can be connected to multiple CBE.CBC Be responsible for CBS Information management , Include ：

• Allocation of serial numbers ;
• Modify or delete eNodeB/NG-RAN Nodes hold CBS news ;
• Through to the eNodeB/NG-RAN Nodes send fixed length CBS Message to start the broadcast , For each language provided by the cell , And fill the page in if necessary 82 Length of octets ;
• determine CBS The set of cells to which messages should be broadcast , And each... Is indicated in the serial number CBS The geographic scope of the message ;
• determine CBS The time when the message began to be broadcast ;
• determine CBS The time when the message should stop broadcasting , And then instruct each eNodeB/NG-RAN Nodes stop CBS The broadcast of news ;
• Determine that the broadcast should be repeated CBS The time period of the message ;
• When CBS When transmitting an emergency message , Distribute “emergency indication” To distinguish from the normal CBS news , Include "Cell ID/Service Area ID list", "warning type", "warning message".

CBCF function ： stay 3GPP in ,CBCF yes 5G A network function in the core network .

CBCF Can be connected to multiple AMF.CBCF Can be connected to multiple CBE.CBCF Be responsible for CBS Information management , Include ：

• Allocation of serial numbers ;
• Modify or delete NG-RAN Nodes hold CBS news ;
• Through to the NG-RAN Nodes send fixed length CBS Message to start the broadcast , For each language provided by the cell , And fill the page in if necessary 82 Length of octets ;
• determine CBS The set of cells to which messages should be broadcast , And each... Is indicated in the serial number CBS The geographic scope of the message ;
• determine CBS The time when the message began to be broadcast ;
• determine CBS The time when the message should stop broadcasting , And then instruct each NG-RAN Nodes stop CBS The broadcast of news ;
• Determine that the broadcast should be repeated CBS The time period of the message ;
• When CBS When transmitting an emergency message , Distribute “emergency indication” To distinguish from the normal CBS news , Include "Cell ID/Service Area ID list", "warning type", "warning message".

CBCF Support for service-based interfaces .CBCF Use AMF The communication service forwards the warning message to NG-RAN, And subscribe to receive notifications related to warning delivery .

Let's take a look at CBCF Protocol stack of

Specific message flow 、 Parameters and message format ,3GPP There are definitions , Interested can be found in 38.041 To see .

In order to send the earthquake and tsunami in time (Earthquake and Tsunami) Wait for public emergency warning messages to be sent to the public ,3GPP stay 5G(NR) Special system messages are defined in the system (SIB6,7 and 8), And the user access in case of emergency is analyzed ( Exemption from authentication and authentication ) Special provisions .

stay 5G In the network, if the core network side AMF Support for this feature has been indicated , Then start the terminal (UE) Can receive public warning messages broadcast by the emergency service center .5G The network defines in the system message for public alert messages 3 Kind of , They are ：

      SIB6:Earthquake and Tsunami Warning System(ETWS Main notice ）;

      SIB7:Earthquake and Tsunami Warning System(ETWS Auxiliary notice );
      SIB8:Commercial Mobile Alert System(CMAS Warning notice );

ETWS Include Main notice , It contains only disaster information in simple mode , Such as “ The earthquake ” or “ tsunami ” or “ tsunami + The earthquake ” etc. . When mobile users (UE) When the main notification message is received , A preset alarm will sound , And display the predetermined text on the screen according to the message content , Notify the user of the danger ; Minor notice Contains detailed text information , Like epicenter 、 Earthquake intensity and other hazard related information .

CMAS yes from SIB8 Carrying Highly urgent notice , It is divided into three types ：

        1. An alert issued by the president or a regional authority ;

        2. Warning of imminent threats to life safety , It is divided into : Extreme and serious threats ;

        3. Amber Alert or child abduction emergency .

5G Network public early warning system

• 5G Cell in the system Public warning and Broadcasting service It belongs to the broadcasting business ;

• Community Broadcasting Center (CBCF) Responsible for sending messages ( Including paid advertising ) Broadcast to end users ;

• Public early warning system (PWS) Specially responsible for earthquake 、 Broadcast of tsunami and other public warning information ;

• CBCF and PWS adopt Namf (N50) Interface to AMF write in ( Replace / Cancel ) Broadcast news ;

• CBCF/PWS In the AMF write in Broadcast You need to provide the message content , news ID, Broadcast frequency and interval, etc ;

• CBCF/PWS Can be specified at any time ID, Replace the message being broadcast .

Public warning message broadcast process

5G Public warning messages in the network , terminal (UE) You can start receiving... After completing emergency registration ; The broadcast process of public warning messages is shown in the following figure ：

AMF Warning message transmission with wireless network

AMF First send ( Or update ) Warning message to NG-RAN, After receiving this message, the wireless network (NG-RAN) Echo receive write ( Or update ) The reply .

AMF towards NG-RAN Send a warning undo request , After receiving the message, the wireless network (NG-RAN) Echo the cancellation reply ;

 

Warning restart indication

 

Warning message failure indication