LTE Non Access Stratum (NAS) Overview

1.          Protocols in LTE-NAS

   EPS Mobility Management (EMM)

­ Supports mobility functions in the UE

   EPS Session Management (ESM)

­ Supports establishment and maintenance of IP connectivity between the UE

and the PDN gateway.

2.          Integrity Protection (IP) and Ciphering of NAS signaling messages

3.          Only support PS domain

4.          (used to tunnel CS SMS when combined attached for EPS and non-EPS) or Fallback (CSFB) to other systems (UMTS, GSM or 1X)

5.          Operating modes:

-          PS mode: LTE only

-          CS/PS mode 1: Non-EPS>LTE

-          CS/PS mode 2: LTE>Non-EPS

6.          GUTI(Globally Unique Temporary Identifier)=> <GUMMEI><M-TMSI>

7.          GUMMEI=><MCC><MNC>

8.          <MME Identifier>=> <MME group ID><MME code>

9.          EPS update status:

-          EU1=>”Updated”

-          EU2=>”Not Updated”

-          EU3=>”Roaming Not Allowed”

10.      EPLMN list – EMM, GMM, and MM shall use the same list.

11.      Timer: T34XX are different with UMTS.

12.      EMM procedures:

-          EMM Common procedures: initiated by MME while a NAS signaling connection exists.

-          EMM Specific procedures: attach, detach, Tracing area procedure (only one at time)

-          EMM Connection Management procedures: establish a secure connection with network or request for sending data

13.      EMM Common Procedures:

-          GUTI Reallocation(MME->UE)

-          Authentication(MME->UE)

-          (Security Mode Control)SMC (MME->UE)

-          Identification (MME->UE)

-          EMM Information(MME->UE)

14.      EMM Specific Procedures:

-          Attach (UE->MME) for resisted, T3410

-          Detach(UE<->MME) T3421 (UE side), T3422(MME side)

-          TAU (UE->MME) T3430

15.      Connection Management Procedures:

-          Service Request(UE->MME) T3417, T3417 Extend

-          Paging (MME->UE)

-          Transport of NAS Message (UE<->MME) Carry CS SMS message

16.      EMM-NAS security:

-Integrity Protection (IP)

-Ciphering

17.      NAS Security Parameters: NAS COUNT, NAS Sequence Number (SN), Security Terminology

18.      EPS Session Management(ESM): {Procedure Transaction ID(PTI), EPS Bearer ID, EPS Bearer, Default EPS bearer, ESM and SM coordination}

-          Procedure related to EPS bearer context

n   Default EPS Bearer Context Activation(MME->UE) T3485

n   Dedicated EPS Bearer Context Activation(MME->UE) T3485

n   EPS Bearer Context Modification (MME->UE) T3486

n   EPS Bearer Context Deactivation (MME->UE) T3495

-          Transaction related procedures

n   PDN Connectivity (UE->MME) T3482

n   PDN Disconnect (UE->MME) T3492

n   Bearer Resource Allocation (UE->MME) T3480

n   Bearer Resource Modification (UE->MME) T3481

n   ESM Information Request (Network Initiated in response to PDN Connectivity Request) (MME->UE) T3489