Telecom Tutorials by Samir Amberkar

LTE - Signaling stacks MME [Under LTE]
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Here we would look at signaling entities at MME.

AT interface Adaptor ESM EMM RRC PDCP RLC MAC PHY		RRM/Relay RRC S1AP PDCP SCTP RLC IP MAC L2 PHY L1		MME AL ESM GTP-C EMM S1AP SCTP   UDP   IP IP L2 L2 L1 L1		SGW AL GTP-C UDP IP L2 L1	Towards PGW
UE	SRBs (RRC SRB0/1/2, MAC LCID 0/1/2)	eNB	S1 (S1AP ID)	MME	GTP-C (IMSI, EPS bearer ID)	SGW

..  MME AL  UE contexts [IMSI, S1AP IDs, bearer IDs]  .. Implementation specific

Towards eNB (S1MME interface)  ..  ESM  Control   UE1    .  .  .    UEn   B1    .  .  .    Bx   B1    .  .  .    By  .. 24.301, EPS bearer context management aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa ..  EMM  Control   UE1    .  .  .    UEn  .. 24.301, mobility management like attach/detach, tracking area update, authentication, providing NAS signaling connection, NAS ciphering and integrity protection ..  S1AP  S1AP control  .. 36.413, UE context management, ERAB management, NAS transport ..  SCTP  SCTP association  .. IETF rfc3309/rfc4106, signaling transport over IP, one association for all UEs ..  IP/L2/L1  IP transport  .. IETF rfc791, IP backbone

Towards SGW (S11 interface)  ..  GTP-C  Control  .. 29.274, signaling plane for GTP tunnel based data plane, one GTP-C TEID per UE, retransmission if reply not received ..  UDP  UDP socket  .. IETF rfc768, one UDP socket for all UEs (?) ..  IP/L2/L1  IP transport  .. IETF rfc791, IP backbone aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

SGW/PGW has GTP-C stack in signaling plane, already covered in this article.

References: 3G Evolution: HSPA and LTE by Dahlman, Parkvall, Sköld, and Beming, LTE - From Theory to Practice, Edited by Sesia, Toufik, and Baker, and SAE and the Evolved Packet Core: Driving the Mobile Broadband Revolution by Olsson, Sultana, Rommer, Frid, and Mulligan.

Copyright © Samir Amberkar 2010-11

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