System Description

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Chapter 1 Samsung LTE System Overview

SOL230 System Description v1.0 3

 Protects and verifies the integrity of control plane data

 Transmits data including sequence number related function

 Removes data and redundant data based on a timer

The RRC layer performs mobility management within the wireless access network,

maintaining and controlling of Radio Bearer (RB), RRC connection management,

and system information transmission, and so on.

MME

The MME interworks with E-UTRAN (eNB) to process the Stream Control

Transmission Protocol (SCTP)-based S1 Application Protocol (S1-AP) signaling

messages for controlling call connections between the MME and the eNB. The

MME also process the SCTP-based NAS signaling messages for controlling

mobility connection and call connection between UE and EPC.

The MME is responsible for collecting/modifying the user information and

authenticating the user by interworking with HSS. It is also responsible for

requesting the allocation/release/change of the bearer path for data routing and

retransmission with GTP-C protocol by interworking with S-GW.

The MME interworks with 2G and 3G systems, Mobile Switching Center (MSC),

and Serving GPRS Support Node (SGSN) for providing mobility and Handover

(HO), Circuit Service (CS) fallback, and Short Message Service (SMS).

The MME is responsible for inter-eNB mobility, idle mode UE reachability,

Tracking Area (TA) list management, choosing P-GW/S-GW, authentication, and

bearer management.

The MME supports mobility during inter-eNB handover and the inter-MME

handover. It also supports SGSN selection function upon handover to 2G or 3G

3GPP network.

S-GW

The S-GW acts as a mobility anchor during inter-eNB handover and inter-3GPP

handover, and routes and forwards user data packets. The S-GW allows the

operator to apply application-specific charging policies to UE, PDN or QCI and

manages the packet transmission layers for uplink/downlink data.

The S-GW also supports GPRS Tunneling Protocol (GTP) and Proxy Mobile IP

(PMIP) by interworking with MME, P-GW, and SGSN.

P-GW

The P-GW is responsible for charging and bearer policy according to the policy

and manages charging and transmission rate according to the service level by

interworking with PCRF. The P-GW also performs packet filtering for each user,

IP address allocation for each UE, and downlink data packet transmission layer

management.

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