national chung cheng university long term evolution and

Microsoft PowerPoint - MCN_LTE&EPC_PPT - 0808 []Long Term Evolution and
Evolved Packet Core Chiang, Wei-Kuo () Associate Professor Department of CSIE National Chung Cheng University Office : EA 311 Phone : 05-2720411~33126 Email : [email protected] URL : http://www.cs.ccu.edu.tw/~wkchiang/
National Chung Cheng University
Why LTE? In contrast to the circuit-switched model of
previous cellular systems, Long Term Evolution (LTE) has been designed to support only packet- switched services.
Mobile Communication Networks LTE & EPC3
3G(UMTS/W-CDMA) 4G(LTE-A) Data Transfer Rate
2Mbps(stationary), 144Kbps(moving vehicle)
the latest mobile network generation.
The LTE network is divided into two parts: the E-UTRAN (air interface)
the Evolved Packet Core (EPC)
EPS(Evolved Packet System)=UE+E-UTRAN+EPC
E-UTRAN & UE The E-UTRAN (Evolved Universal Terrestrial
Radio Access Network) deals with radio access technologies, User equipment (UE) connects to an eNodeB via radio interface.
The eNodeB performs radio resource management functions such as allocating radio resources and managing inter-cell interference.
The eNodeB connects to a serving gateway (SGW) through mobile backhaul network.
Evolved Packet Core (EPC) The EPC deals with the technology related to a
core network. The subcomponents of the EPC are:
1. Serving Gateway (SGW)
4. Policy and Charging Rules Function (PCRF)
5. Home Subscriber Server (HSS)
Architecture of LTE/EPC The mobility management entity (MME) is the
main control entity. It is responsible for: Maintaining mobility management states for UEs
Setting up bearers to carry user traffic
UE authentication and authorization(with HSS)
Intra-3GPP mobility management.
Architecture of LTE/EPC The serving gateway (SGW) serves a large
number of eNodeBs, and acts as the local mobility anchor point for the inter-eNodeB handover.
The PDN gateway (PGW) performs UE IP address allocation, policy enforcement, packet filtering and charging. It is a termination point for the packet data interface towards the external network.
These gateways are both responsible for data forwarding, IP mobility and QoS control at the data plane.
Architecture of LTE/EPC The policy and charging rules function (PCRF)
provides QoS and charging rules to the PGW. The home subscriber server (HSS) is a central
database where user profiles are stored. It is in charge of UE authentication and authorization.
GPRS Tunneling Protocol GPRS Tunneling Protocol (GTP) is a IP-based
communications protocols used to carry general packet radio service (GPRS) within GSM, UMTS and LTE networks.
GTP provides IP mobility when user move around. That is, UE IP address remains the same wherever UE goes.
GTP is used to establish a GTP tunnel, for UE, between SGW and PGW, eNodeB and SGW, and SGW and MME.
http://www.netmanias.com/ko/post/blog/5836/eps-bearer-gtp-tunnel-lte/lte-gtp-tunnel-i
LTE/EPC Data Forwarding When the UE is in IDLE state, the radio data
bearer (i.e. between UE and eNB) and the S1 data bearer (i.e. between eNB and SGW) are released.
The S5 data bearer (i.e. between SGW and PGW) is maintained as long as the UE is registered to the network.
Bearer An EPS Bearer is an IP packet flow with a
defined quality of service (QoS) between the gateway and the UE.
Multiple bearers can be established for a user in order to provide different QoS streams.
Bearer Broadly, bearers can be classified into two
categories based on the nature of the QoS they provide: GBR (Guaranteed bit rate) bearer: If dedicated network resources related to the bearer are permanently allocated, it is called GBR bearer.
Non-GBR bearer: It does not guarantee any particular bit rate. No bandwidth resources are allocated permanently to the Non-GBR bearer.
Bearer Upon UE is assigned an IP address by the P-GW
, at least one bearer is established. This is called the default bearer, and it remains established throughout the lifetime of connection to provide the UE with always-on IP connectivity.
Default bearer is always a non-GBR bearer since it is permanently established.
Any additional bearers called dedicated bearers can also be established at any time during the same connection. A dedicated bearer can be either a GBR or a non-GBR bearer.
• Non-GBRbearer Non-GBR bearer GBR bearer
• EPS always-onDefault Bearer attachDefault BearerDefault Bearer Non-GBR Bearer(always-on )
Bearer
Bearer Each bearer has an QCI (QoS Class Identifier).
Each QCI is characterized by priority, packet delay budget and acceptable packet loss rate.
QCI Resource type
2 4 150 10-3 Conversational Video (Live Streaming)
3 3 50 10-3 Real Time Gaming
4 5 300 10-6 Non-Conversational Video (Buffered Streaming)
5 Non-GBR 1 100 10-6 IMS Signalling
6 6 300 10-6 TCP-based (e.g., www, e-mail, ftp, p2p file sharing, etc.)
7 7 100 10-3 Voice, Video (Live Streaming)Interactive Gaming
Standardized QCIs form Specs 23.203 P.30
Bearer Packet filtering into different bearers is based
on TFTs (Traffic flow template). TFTs use IP header information(such as source /destination IP addresses and TCP port numbers) to filter packets.
An Uplink TFT (UL TFT) associated with each bearer in the UE filters IP packets to EPS bearers in the uplink direction.
A Downlink TFT (DL TFT) in the P-GW is a similar set of downlink packet filters.
Bearer The S-GW stores a one-to-one mapping between
an S1 bearer and an S5/S8 bearer. Similarly, eNodeB stores a one-to-one mapping
between a radio bearer ID and an S1 bearer. The bearer is identified by the GTP Tunnel
endpoint identifier (TEID).
EPS Mobility Management
EPS Connection Management
Radio Resource Control
3GPP TS 23.401 v14.0.0 (2016-06) CH4.6 EPS Mobility Management and Connection Management states
Detailed Reference: http://www.netmanias.com/en/post/techdocs/5909/ecm-emm-lte-mobility/lte-emm-and-ecm-states
UE States The EPS Mobility Management (EMM) states
describe the Mobility Management states that result from the mobility management procedures.
There are two EMM states described in SPEC: 1. EMM-DEREGISTERED.
2. EMM-REGISTERED.
EPS Mobility Management In the EMM-DEREGISTERED state, the EMM
context in MME holds no valid location or routing information for the UE. The UE is not reachable by a MME, as the UE location is not known.
UE can enters the EMM-REGISTERED state by a successful registration with an Attach procedure. In this state, the UE can receive services that require registration in the EPS.
EMM-DEREGISTERED EMM-REGISTERED
Attach Accept
3GPP TS 23.401 v14.0.0 (2016-06) Figure 4.6.4-1: EMM state model in UE
describe the signalling connectivity between the UE and the EPC.
There are two ECM states described in SPEC: 1. ECM-IDLE.
2. ECM-CONNECTION.
EPS Connection Management A UE is in ECM-IDLE state when no signalling
connection between UE and network exists. There exists no UE context in E-UTRAN, but MME retains the UE context and the information about the established bearers.
To allow the network to contact an ECM-IDLE UE, the UE updates to the network whenever it moves out of its current tracking area (TA). It is called a tracking area update. The MME is responsible for keeping track of the user location while the UE is in ECM-IDLE.
EPS Connection Management When UE is in ECM-CONNECTION state, the UE
location is known in the MME with an accuracy of a serving eNodeB ID.
ECM-IDLE ECM-CONNECTED
RRC connection established(Service trigger)
3GPP TS 23.401 v14.0.0 (2016-06) Figure 4.6.4-3: ECM state model in UE
There are two RRC states described in SPEC: 1. RRC-IDLE.
2. RRC-CONNECTION.
It depends on whether an RRC connection is established or not.

national chung cheng university long term evolution and

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