LTE Architecture KANNAN M JTO(3G)

LTE System Architecture-EPS EPC E-UTRAN eNode B HSS MME P-GW Every Mobile telecommunication system will have 3 element structure. A Radio air iterface A Radio access network And a core network. Here also the structure is same The air interface which connects the Mobile to Radio access network is called Evolved UTRA or E-UTRA. This equivalent Um interface of UMTS. The Radio Access network is called Evolved UTRAN or E- UTRAN . This is equivalent of UTRAN in UMTS The core network is called Evolved packet Core. This an all IP packet core NW. The CN provides access to external packet IP networks The E-UTRAN and EPC is together known as Evolved Packet system EPS. EPS is also called System architecture for Evolution SAE. S-GW eNode B Evolved Packet Core (EPC) E UTRA

LTE System Architecture-EPS Internet & Operator services EPC This is simplified architecture, consists of E-UTRA, E-UTRAN and EPC. EPC interfaces internet and other services. Now we will see the detailed architecture. E-UTRAN

Evolved Packet Core (EPC) 2G/3G UTRAN HSS MME E- UTRAN Trusted IP NWs P-GW This is the the detailed EPC architecture. It consists of An MME, S-GW , P-GW ePDG and an HSS. You can see that MME and S-GW inter faces the EPC with Radio access network. P-GW and ePDG interfaces EPC with other Packet or operator services like internet. HSS is the data base centre. We will see each and every element in detail. There is no circuit switched core network for services like Voice. This different from 2G / 3G. S-GW Operator Services ePDG Non-Trusted IP NWs

EPC –Home Subscriber Server Master subscriber database Stores user related information like, subscription parameters, user identification, service profile, user location etc Generates security related information It can be treated as an “upgraded HLR” with GSM, GPRS, LTE and IMS information Master subscriber database Stores user related information like, subscription parameters, user identification, service profile, user location etc Generates security related information ie it carries the functionality of AuC It can be treated as an “upgraded HLR” with GSM, GPRS, LTE and IMS information

EPC –Mobility Management Entity Main control node Handles the control plane signaling Idle mode UE tracking Bearer activation / de-activation Choice of SGW and PGW for a UE Mobility anchoring Interacting with HSS to authenticate user Provides temporary identities for UEs Paging procedure Coordinating LI MME is the main control element in EPC. It Handles the control plane signaling – From R4 onwards control and bearer switching parts are separated in core NWs. In UMTS this introduced MSC servers and MGWs. Where the MSC server handles the control functionality and MGW will do the switching functionality. Here MME is handling the control functionality.. So it terminates the control messages from E-UTRAN. Idle mode UE tracking - location of the UE in idle mode as done by the MSC in legacy systems. Bearer activation / de-activation – Call control or call set up Choice of SGW and PGW for a UE – This is because sevral SGW and PGW may be connected to same MME for different services. Mobility anchoring- It will coordinate Handovers in certain cases. Interacting with HSS to authenticate user Provides temporary identities for UEs – like TMSI in GSM Paging procedure will be cordited Coordinating LI Now it seems that is almost similar to our MSC server in UMTS. But MSC server in Circuitswitched core NW. But MME is Packet core element. We can treat MME as the cotrol part of SGSN. One MME can be connected to more than one S-GWs.

EPC –Serving GateWay SGW is the data plane interface of EPC. A data plane element An interface for the data packet network at the E-UTRAN. The SGW maintains the data paths between the eNodeBs and the PDN Gateways Routes user data packets between E-UTRAN and P-GW When UEs move across areas served by different eNodeBs, the SGW serves as a mobility anchor ensuring that the data path is maintained SGW is the data plane interface of EPC. Forms an interface for the data packet network at the E-UTRAN. The SGW maintains the data paths between the eNodeBs and the PDN Gateways Routes user data packets between E-UTRAN and P-GW When UEs move across areas served by different eNodeBs, the SGW serves as a mobility anchor ensuring that the data path is maintained. Also it will handle the data path when a handover to other RATs happens. Can be treated as the data part of the SGSN or MGW of circuit core. It supports LI

EPC –Packet Data Network GateWay A data plane element provides connectivity for the UE to external packet data networks The UE may have connectivity with more than one PGW for accessing multiple PDNs Charging QoS control IP address allocation This is a data plane element provides connectivity for the UE to external packet data networks The UE may have connectivity with more than one PGW for accessing multiple PDNs Charging QoS control IP address allocation This is some what similar to GGSN

EPC – evolved PDG (ePDG) Gateway used for Interworking with non trusted non 3GPP IP access systems Provides some additional security mechanisms Gateway used for Interworking with non trusted non 3GPP IP access systems Provides some additional security mechanisms

Evolved UTRAN Architecture S1 -MME X2 MME X2 This is the E-UTRAN architecture As u can see, there only one element in E-UTRAN , the eNodeB. No RNC is there . All eNodeBs are directly connected to core network. Now there are two interfaces towards core network from eNodeB. One is towards MME and other is towards S-GW. In addition to that neighboring NodeBs are interconnected by X2 interface. S1- U X2 S-GW E-UTRAN E-PC

eNode B The lone NE in the E-UTRAN Functionality of RNC moved to Node B, which reduces the number of nodes and there by complexity and latency of the network It does the RRM functionality Controls the scheduling Transmission of paging & Broadcast information Selection of MME during registration Measurement configuration Routing of user data to the S-GW The lone NE in the E-UTRAN Functionality of RNC moved to Node B, which reduces the number of nodes and there by complexity and latency of the network It does the RRM functionality- In UMTS it was done by RNC Controls the scheduling data Transmission of paging & Broadcast information Selection of MME during registration- One E-Node B may be connected to different vendors and so different MMEs. In that case eNodeBs will rote the signaling messages to the corresponding MMEs Measurement configuration- What to measure, when to measure etc. Routing of user data to the S-GW

eNode B Interfaces S1 MME Connects eNodeBs with MME It is control / signaling plane interface S1 U Connects eNodeBs with S-GW It is user plane interface It transports actual user data /packets 3 types of interfaces are there in eNodeB. S1MME, S1U and X2 S1 MME Connects eNodeBs with MME It is control / signaling plane interface S1 U Connects eNodeBs with S-GW It is user plane interface It transports actual user data /packets towards the core network.

eNode B Interfaces X2 Connects eNodeBs with neighboring e-NodeBs e Node Bs communicate directly with each other for cell reselection, intra LTE handover procedures, inter cell interference coordination etc through this X2 interface. This is some what similar to Iur interface of UMTS UTRAN Connects eNodeBs with neighboring e-NodeBs e Node Bs communicate directly with each other for cell reselection, intra LTE handover procedures, inter cell interference coordination etc through this X2 interface. This is some what similar to Iur interface of UMTS UTRAN LTE is termed as SON self optimizing network. I.e. it will adjust the frequency and power in consultation with adjacent network. For this communication it uses this interface ICIC

One RAN, Simplify your Network Disadvantages High CAPEX Buy systems separately Deploy systems separately High OPEX Operate systems separately Maintain systems separately Performance Down Bad intersystem coordination High intersystem interference Reliability Down - Fault point & risk increasing - Hard for trouble shooting Advantages Reduce Capax and Opex Reduce Investment Risk Quick responses to market opportunities Improve users’ experience GSM Expansion Core Network SingleRAN GSM / UMTS / HSPA / LTE Backhaul UMTS/HSPA Introduced Legacy GSM Network LTE in the coming future Convergence Equipment Level Site Level Operation Level 14

REFERENCES www.3gpp.org www.radio-electronics.com www.lteuniversity.com www.cert.nat.tn

Thank You kannanmohanan@gmail.com