Content for  TS 23.554  Word version:  19.3.0

An MSGin5G Server provides server-side functionality to assist MSGin5G Clients with the sending and receiving of messages via the MSGin5G Service to/from Application Servers and/or other MSGin5G Service endpoints on other UEs, and collect charging information from MSGin5G message. Functionalities of MSGin5G Server:

• To manage MSGin5G UEs that are home to the MSGin5G Server and provides:
  • handling the registration of these MSGin5G UEs
  • handling the message initiation by these MSGin5G UEs
  • handling the message delivery to these MSGin5G UEs
• To deliver messages to an MSGin5G Service endpoint based on the terminating MSGin5G Service ID. The terminating MSGin5G Service ID may be served by the same MSGin5G Server or served by another MSGin5G Server. If the MSGin5G Service ID is served by another MSGin5G Server, the MSGin5G Server forwards the messages to the next MSGin5G Server until it reaches to the MSGin5G Server that is the home of the terminating MSGin5G Service ID;
• To resolve the MSGin5G Group Service ID to determine the members of the Group as specified in TS 23.434;
• Interworking with non 3GPP messaging service through the Non-3GPP Message Gateway;
• Interworking with legacy 3GPP messaging service through the Legacy 3GPP Message Gateway;
• Interworking with a 3GPP broadcast service through the Broadcast Message Gateway;
• Exchanging MSGin5G messages with Application Servers, MSGin5G Clients, Legacy 3GPP Message Gateway, and Non-3GPP Message Gateway;
• Supporting MSGin5G message segmentation according to service provider's policy;
• Supporting UE configuration procedures as specified in TS 23.434 or communicating with the SEAL Configuration Management Server to provide MSGin5G configuration data on a UE to be ready for the MSGin5G Service;
• Managing information related to the MSGin5G Service, such as MSGin5G Client Triggering Information, MSGin5G Client availability and MSGin5G Client Supported MSGin5G segment size, and Broadcast Message Gateway;
• Support store and forward of messages based on the sender request and the availability and reachability of the service endpoints, and
• Interactions towards the CHF, as defined in TS 32.240, to collect charging information from MSGin5G message according to the operator's charging policy and report charging information to CHF.

Upon receiving the MSGin5G message request to deliver the message to the recipient (which could be any of the MSGin5G UE, Legacy 3GPP UE, Non-3GPP UE or Application Server), the MSGin5G Server checks the recipient's registration status (created at the time of each MSGin5G UE/Application Server registration to MSGin5G Server, or the Message Gateway performs registration with the MSGin5G Server on behalf of the Non-MSGin5G UEs) for availability and reachability of MSGin5G service endpoints. The MSGin5G Server will attempt for delivery of the MSGin5G message request towards recipient based on the UE Service ID/AS Service ID, if the recipient is available and reachable. If the recipient is unavailable, the MSGin5G Server stores the message for deferred delivery unless the sender or the recipient opted out of store and forward services. If the recipient is Non-MSGin5G UE, the Legacy 3GPP Message Gateway or the Non-3GPP Message Gateway that the Non-MSGin5G UE is registered with, will receive the MSGin5G message request on behalf of the Non-MSGin5G UE, and then delivers the message to the Non-MSGin5G UE by using the Non-MSGin5G message delivery mechanism. If the message is a Broadcast message, the Broadcast Message Gateway will receive the MSGin5G message request and will deliver the message to all UEs in the Broadcast Area via the Broadcast messaging delivery mechanism, based on the Broadcast Area ID.

An MSGin5G Client provides client-side functionality for UE Application Clients with the sending and receiving of messages via the MSGin5G Service to/from Application Servers and/or other MSGin5G Service endpoints; i.e. UEs. Functionalities of MSGin5G Client including:

• may expose MSGin5G APIs to enable Application Clients to use an MSGin5G Service;
• supporting (de-)registration of an MSGin5G Client to an MSGin5G Server to use MSGin5G Service;
• supporting configuration of an MSGin5G Client required to use MSGin5G Service;
• construction of MSGin5G message when requested by a native application or Application Client;
• delivery of MSGin5G message payload to the targeted native application or Application Client;
• exchanging MSGin5G messages via an MSGin5G Server to/from Application Servers and/or other MSGin5G Service endpoints; i.e. UEs;
• support MSGin5G message segmentation and re-assembly;
• support MSGin5G message aggregation and segregation

An MSGin5G Gateway Client is an MSGin5G Client which supports MSGin5G Gateway service functionality in addition to the MSGin5G Client functionalities specified in clause 5.3.3.1. It enables constrained devices to obtain services from the MSGin5G Server when communications via ProSe UE-to-Network Relay are not or cannot be supported. The MSGin5G Gateway service functionality in the MSGin5G Gateway Client supports:

• supporting the bulk configuration and bulk (de-)registration for the MSGin5G Client residing on the Constrained UE, e.g. checking whether bulk configuration/bulk (de-)registration can be used, holding the (de-)registration request from MSGin5G Client residing on the constrained device, construction of the bulk (de-)registration request and splitting of the MSGin5G UE bulk (de-)registration response.

A Message Gateway in the MSGin5G application architecture provides functionality to deliver MSGin5G messages to Non-MSGin5G UEs. A Message Gateway performs the role of interconnecting two different messaging delivery mechanisms and assures the message integrity between different message delivery mechanisms. A message delivery mechanism comprises the specific set of protocols, procedures and rules. Functionalities of Message Gateway:

• Enables seamless delivery of an MSGin5G message between different message delivery mechanisms with integrity;
• Communicates with the MSGin5G Server using either an MSGin5G Client functionality or similar functions to enable sending and receiving MSGin5G messages;
• Delivers payload of an MSGin5G message to the Non-MSGin5G UE using the specific message delivery mechanism available to that Non-MSGin5G UE and vice versa;
• Performs message sender and receiver addresses conversion according to the two connected message delivery mechanisms and maintain the mapping of the address pair used for a response message delivery;
• Perform registration and de-registration with the MSGin5G Server on behalf of the Non-MSGin5G UEs;
• Act as a service endpoint to perform message segmentation and reassembly for the Non-MSGin5G UEs when needed;
• Act as a service endpoint to split the aggregated MSGin5G message into multiple individual MSGin5G message requests for the Non-MSGin5G UEs; and
• Performs protocol conversion according to the service supported by the target UE;
• Supports the MSGin5G message delivery status report
  1. If application level message delivery status report is not supported by the Non-MSGin5G message delivery mechanisms, based on the information (e.g. response to the message delivery request, transport level information, etc) obtained from the Non-MSGin5G message delivery mechanisms, the Message Gateway fetches the delivery status from the above information and uses it to create an MSGin5G message delivery status report on behalf of Non-MSGin5G UE. If the delivery status is failure, also fetch the suitable failure reason from the above information and use it as reason of failure in the MSGin5G message delivery status report.
  2. If application level message delivery status report is supported by the Non-MSGin5G message delivery mechanisms (e.g. RCS specified in GSMA PRD RCC.07 [3]), translates the application level message delivery status report in the Non-MSGin5G message delivery mechanisms to MSGin5G message delivery status report.

There are three types of Message Gateways used to deliver MSGin5G messages to different UE types: the Legacy 3GPP Message Gateway, the non-3GPP Message Gateway, and the Broadcast Message Gateway.

The Legacy 3GPP Message Gateway is used to deliver MSGin5G message to Legacy 3GPP UEs, using their 3GPP supported message delivery mechanisms.

The Non-3GPP Message Gateway is used to deliver MSGin5G message to Non-MSGin5G UEs, using their (non-3GPP) supported message delivery mechanisms.

The Broadcast Message Gateway is used to deliver MSGin5G message to MSGin5G UEs, Legacy 3GPP UEs or Non-MSGin5G UEs in a Broadcast Area.