LTE Roaming

Agenda

Introduction

Roaming Scenarios

Data

SMS

Voice

IMS

Other considerations

LTE Roaming Situation

None of Verizon LTE subscribers can roam on another LTE network, not even on other 700 MHz LTE networks in the US

Roaming on 3G networks and their HSPA+ derivates is much easier, one reason being the fairly limited number of bands involved

Considering the 473 commercial HSPA networks in 180 countries, it is much easier to maintain current 3G roaming agreements (without LTE)

Architecture Overview

Nodes Interface ID Protocol

MME - HSS S6a Diameter Base Protocol (IETF RFC 3588 [3]) and 3GPP TS

29.272 [8])

SGW - PGW S8 GTP (GTP-C 3GPP TS 29.274 [4] and GTP-U 3GPP TS 29.281 [5])

or PMIP (IETF RFC 5213 [20]) and

3GPP TS 29.275 [23])

hPCRF - vPCRF S9 Diameter Base Protocol (IETF RFC 3588 [3]) and 3GPP TS

29.125 [6])

MAP to Diameter Transition Todays 2G/3G networks use SS7-MAP protocol for

location/subscriber/access/handover/authentication/security/identity management & handover services

However, in LTE/SAE (3GPP Rel. 8), Diameter protocol has been chosen for many of these procedures and is increasingly used for inter-operator signalling network and roaming infrastructure

In LTE environment, registration messages received would be based on Diameter (rather than SS7-MAP)

Diameter Base Protocol is defined within IETF RFC 3588 (published in September 2003)

Based on Diameter Base Protocol, 3GPP (like IETF) has also defined some specific Diameter applications to support more specific requirements in different scenarios

From GRX to IPX

Roaming Scenarios Data

2G/3G-only VPMN (Visited Public Mobile Network)

2G/3G-only HPMN (Home Public Mobile Network)

LTE-deployed with 2G/3G agreement

LTE-deployed with 2G/3G & LTE agreement

SMS & Voice

SMS over SG

CSFB (Circuit Switched Fall Back)

VoLTE (Voice over LTE)

IMS

2G/3G-only VPMN From the 2G/3G VPMN, the EPS

HPMN looks like a GPRS network. It is assumed that the MAP-Diameter

IWF function is performed by the EPS operator.

The PDN Gateway in HPMN implements the Gp interface towards the SGSN in VPMN.

The HPMN implements the Gr interface or supports Gr functionality via an IWF to enable the authentication of its customers in the VPMN.

No changes to the existing GTPv1 and MAP roaming interfaces at the VPMN are required.

2G/3G-only HPMN There is an explicit agreement with

the HPMN to allow this roaming scenario.

The HPMN is fully aware that none of the services requiring Home Routing will work.

The VPMN (or the HPMN, or a third party) has deployed an IWF between S6a and Gr (a MAP-Diameter translator).

The MME in VPMN can do the mapping of the subscription data for Gn/Gp SGSN provided by the HLR.

The HLR has been upgraded with support for LTE security parameters and supports Gr+ interface (Release 8 or later).

LTE Deployed 2G/3G Roaming Agreement Only

Scenario 1: Legacy GPRS Roaming Scenario 2: HPMN only has PGW as the gateway for roaming

LTE Deployed 2G/3G Roaming Agreement Only

Scenario 3: HPMN has both GGSN and PGW as the gateway for roaming

LTE Deployed 2G/3G and LTE Roaming Agreement

Scenario 1: HPMN only has PGW as the gateway for roaming, 2G/3G Access via Gp interface.

Scenario 2: HPMN has both GGSN and PGW as the gateway for roaming, 2G/3G Access via Gp interface.

LTE Deployed 2G/3G and LTE Roaming Agreement

Scenario 3: HPMN has only PGW as the gateway for roaming, 2G/3G Access via S4/S8 interfaces.

Scenario 4: HPMN has both PGW and GGSN as the gateway for roaming, 2G/3G Access via S4/S8 or Gp interfaces.

SMS over SG Roaming

CSFB Roaming

VoLTE Roaming Architecture

VoLTE Roaming Implementation

HPMN VPMN Roaming Implementation

VoLTE 2G/3G Only CS Roaming

2G/3G & LTE Data-only CS Roaming

2G/3G & LTE CSFB CS Roaming

2G/3G & LTE CSFB/VoLTE-SRVCC CS & IMS Roaming

2G/3G & LTE CSFB/VoLTE-SRVCC&PS-HO CS & IMS Roaming

LTE PS-HO IMS Roaming

Operational Requirements for IMS Voice and Conversational Services

Routing of media for Voice & video over IMS (VoIMS; includes IR.58, IR.92 and IR.94) when call originator is Roaming should be at least as optimal as that of current Circuit Switched (CS) domain.

The charging model for roaming used in CS domain shall be maintained in VoIMS.

Allow the HPMN to decide, based on service and commercial considerations & regulatory obligations, to enforce the routing of the traffic to itself (home routing).

IMS Roaming Configurations

P-GW/GGSN in the Visited network via Visited Network IM subsystem

P-GW/GGSN in the Visited network

P-GW/GGSN in the Home network

Source: 3GPP TS 23.221 & GSMA IR.65

IMS Roaming Configurations

No IMS Interworking required in options 2 & 3

UE eNodeB S-GW P-GW IMS

UE eNodeB S-GW P-GW IMS

Option 1 Option 2 Option 3 HPMN VPMN

IMS-to-IMS Interworking

Ici/Izi Interfaces

3GPP TS 29.165 Mw & Gi/Sgi Interfaces

Other Potential Impacts Roaming Agreements Fraud Impacts:

Although minor, some changes are expected in fraud solution requirements Billing & Charging, Invoicing

Is current 2G/3G applicable to LTE? Impact on Roaming VAS

Some VAS platforms used in roaming are still SS7/MAP-based Regulation Impact:

Would VoLTE follow voice & SMS regulations or data regulations? Impact on Roamer Steering

Most roamer steering solutions are SS7/MAP-based Non-3GPP Roaming Partners:

Non-3GPP roaming partner will need to implement the GSMA roaming guidelines

Applicable Standards GSMA GSMA IR.88 LTE Roaming Guidelines GSMA IR.92 IMS Profile for Voice & SMS (UE to IMS core interface) GSMA IR.65 IMS Roaming & Interworking Guidelines GSMA PRD IR.33 - GPRS Roaming Guidelines GSMA PRD IR.34 - Inter-PLMN Backbone Guidelines GSMA PRD IR.40 - Guidelines for IPv4 Addressing and AS Numbering for

GRX/IPX Network Infrastructure and User Terminals GSMA PRD BA.27 Charging Requirements in Roaming GSMA PRD IR.67 - DNS/ENUM Guidelines for Service Providers &

GRX/IPX Providers GSMA PRD IR.80 - Technical Architecture Alternatives for Open

Connectivity Roaming Hubbing Model

3GPP 3GPP TS 23.221 Architectural Requirements

THANK YOU

Slide Number 1AgendaLTE Roaming SituationArchitecture OverviewMAP to Diameter TransitionFrom GRX to IPXRoaming Scenarios2G/3G-only VPMN2G/3G-only HPMNLTE Deployed Slide Number 11LTE Deployed LTE Deployed SMS over SG RoamingCSFB RoamingVoLTE Roaming ArchitectureVoLTE Roaming ImplementationOperational Requirements for IMS Voice and Conversational ServicesIMS Roaming ConfigurationsIMS Roaming ConfigurationsIMS-to-IMS InterworkingOther Potential ImpactsApplicable StandardsSlide Number 24