© Tata Consultancy Services Ltd LTE Basics/ Architecture

Agenda Overview of Telecom Networks Standardization Motivation for LTE LTE performance requirements LTE challenges LTE technology basics LTE 3GPP Releases LTE/SAE Key Features LTE Architecture Summary

Overview of Telecom Networks Evolution of Radio Access Technologies LTE (3.9G) : 3GPP release 8~9 LTE-Advanced : 3GPP release d/e m

Overview of Telecom Networks Contd.. Telecom Network Based on Subscriber Growth More than 1 Billion HSPA/LTE Subscribers today Projection for nearly 5 Billion HSPA/LTE subscribers by 2017

5 Overview of Telecom Networks Contd.. Focus on Telecom Network Family Evolution with data rates EDGE EDGE+ W-CDMA HSPA HSPA LTE LTE-Advanced Kb/s 1Mb/s 384Kb/s 42Mb/s18Mb/s 100Mb/s 1000Mb/s Standards availability

Comparison

Standardization LTE is the latest standard in the mobile network technology tree that previously realized the GSM/EDGE and UMTS/HSxPA network technologies that now account for over 85% of all mobile subscribers. LTE will ensure 3GPP’s competitive edge over other cellular technologies. 3GPP work on the Evolution of the 3G Mobile System started in November Specifications scheduled finalized by the end of December Currently, standardization in progress in the form of Rel ‐ 11 and Rel ‐ 12

Motivation for LTE Need for higher data rates and greater spectral efficiency –Can be achieved with HSDPA/HSUPA –and/or new air interface defined by 3GPP LTE Need for Packet Switched optimized system –Evolve UMTS towards packet only system Need for high quality of services –Use of licensed frequencies to guarantee quality of services –Always ‐ on experience (reduce control plane latency significantly) –Reduce round trip delay Need for cheaper infrastructure Simplify architecture, reduce number of network elements

ITU/BDT Arab Regional Workshop on “4G Wireless Systems” – Tunisia LTE Overvi ew 9 LTE Performance requirements Data Rate: –Instantaneous downlink peak data rate of 100Mbit/s in a 20MHz downlink spectrum (i.e. 5 bit/s/Hz) –Instantaneous uplink peak data rate of 50Mbit/s in a 20MHz uplink spectrum (i.e. 2.5 bit/s/Hz) Cell range –5 km ‐ optimal size –30km sizes with reasonable performance –up to 100 km cell sizes supported with acceptable performance Cell capacity –up to 200 active users per cell(5 MHz) (i.e., 200 active data clients)

ITU/BDT Arab Regional Workshop on “4G Wireless Systems” – Tunisia 2010 LTE Overvi ew 10 LTE performance requirements – Cont. Mobility –Optimized for low mobility(0 ‐ 15km/h) but supports high speed Latency –user plane < 5ms < 5ms –control plane < 50 ms Improved spectrum efficiency Improved broadcasting IP ‐ optimized Scalable bandwidth of 20, 15, 10, 5, 3 and 1.4MHz Co ‐ existence with legacy standards

What are the LTE challenges? The Users’ expectation… Best price, transparent flat rate Full Internet Multimedia..leads to the operator’s challenges reduce cost per bit provide high data rate provide low latency User experience will have an impact on ARPU Price per Mbyte has to be reduced to remain profitable Cost per MByte Throughput Latency HSPALTE UMTS HSPAI-HSPALTE

ITU/BDT Arab Regional Workshop on “4G Wireless Systems” – Tunisia 2010 Comparison of Throughput and Latency Peak data rates around 300Mbps/80 Mbps Low latency ms Enhanced consumer experience: drives subscriber uptake allow for new applications provide additional revenue streams Latency (Rountrip delay)* Max. peak data rate Downlink Uplink GSM/ EDGE HSPA Rel6 Mbps HSPAevo (Rel8) HSPA R6 Evolved HSPA (Rel. 7/8, 2x2 MIMO) LTE 2x20 MHz (2x2 MIMO) LTE 2x20 MHz (4x4 MIMO) 50 0 LTE min max ms DSL (~20-50 ms, depending on operator) 0 10 * Server near RAN LTE challenges continued..?

ITU/BDT Arab Regional Workshop on “4G Wireless Systems” – Tunisia LTE Overvi ew 13 Scalable Bandwidth Scalable bandwidth of 1.4 – 20 MHz Easy to introduce on any frequency band: Frequency Refarming (Cost efficient deployment on lower frequency bands supported) LTE challenges continued..? Scalable bandwidth 1.4 – 20 MHz using different number of subcarriers Large bandwidth provides high data rates Small bandwidth allows simpler spectrum reframing, e.g. 450 MHz and 900 MHz Bandwidth 1.4 MHz Narrow Spectrum Reframing 3.0 MHz 5 MHz 10 MHz High Data Rates 15 MHz 20 MHz

Increased Spectral Efficiency All cases assume 2 ‐ antenna terminal reception HSPA R7, WiMAX and LTE assume 2 ‐ antenna BTS transmission (2x2 MIMO) ITU contribution from Downlink WiMAX Forum shows downlink 1.3 and uplink 0.8 bps/Hz/cell bps/H z/cell Uplink Reference: -HSPA R6 and LTE R8 from 3GPP R HSPA R6 equalizer from 3GPP R HSPA R7 and WiMAX from NSN/Nokia simulations HSPA R6HSPA R6 +HSPA R7WiMAXLTE R8 LTE challenges continued..?

ITU/BDT Arab Regional Workshop on “4G Wireless Systems” – Tunisia 2010 LTE Overvi ew 15 Reduced Network Complexity Flat, scalable IP based architecture Flat Architecture: 2 nodes architecture IP based Interfaces Flat, IP based architecture AccessCoreControl Flat networks are MMIMHLR/H ESSS characterized by fewer network elements, lower latency, greater flexibility and lower operation cost Evolved Node B GateWay Internet LTE challenges continued..?

LTE/SAE Key Features – Overview EPS ( Evolved Packet System ) / SAE ( System Architecture Evolution ) / LTE ( Long Term Evolution ) EUTRAN ( Evolved UTRAN ) EPC ( Evolved Packet Core ) IP Network PS Domain only, No CS Domain IP Network Evolved Node B / No RNC IP Transport Layer UL/DL resource scheduling IP Transport Layer QoS Aware 3GPP (GTP) or OFDMA/SC-FDMA MIMO ( beam-forming/ spatial multiplexing) HARQ QoS Aware Self Configuration IETF (MIPv6) Prepared for Non- 3GPP Access Scalable bandwidth (1.4, 3, 5, 10,.. 20 MHz)

LTE/SAE Key Features Evolved NodeB –No RNC is provided anymore –The evolved Node Bs take over all radio management functionality. –This will make radio management faster and hopefully the network architecture simpler IP transport layer –EUTRAN exclusively uses IP as transport layer UL/DL resource scheduling –In UMTS physical resources are either shared or dedicated –Evolved Node B handles all physical resource via a scheduler and assigns them dynamically to users and channels –This provides greater flexibility than the older system

LTE/SAE Key Features – Cont. Frequency Domain Scheduling : –Frequency domain scheduling uses those resource blocks that are not faded –Not possible in CDMA based system Carrier bandwidth Resource block Frequency Transmit on those resource blocks that are not faded

LTE/SAE Key Features – Cont. HARQ –Hybrid Automatic Retransmission on reQuest –HARQ has already been used for HSDPA and HSUPA. –HARQ especially increases the performance (delay and throughput) for cell edge users. –HARQ simply implements a retransmission protocol on layer 1/2 that allows to send retransmitted blocks with different coding than the 1 st one. HARQ Hybrid Automatic Repeat Request

LTE/SAE Key Features – Cont. QoS awareness –The scheduler must handle and distinguish different quality of service classes –Otherwise real time services would not be possible via EUTRAN –The system provides the possibility for differentiated service Self configuration –Currently under investigation –Possibility to let Evolved Node Bs configure themselves It will not completely substitute the manual configuration and optimization.

LTE/SAE Key Features – Cont. Packet Switched Domain only –No circuit switched domain is provided –If CS applications are required, they must be implemented via IP Non ‐ 3GPP access –The EPC will be prepared also to be used by non ‐ 3GPP access networks (e.g. LAN, WLAN, WiMAX, etc.) –This will provide true convergence of different packet radio access system

LTE/SAE Key Features – Cont. MIMO –Multiple Input Multiple Output –LTE will support MIMO as an option, –It describes the possibility to have multiple transmitter and receiver antennas in a system. –Up to four antennas can be used by a single LTE cell (gain: spatial multiplexing) –MIMO is considered to be the core technology to increase spectral efficiency.

LTE technology basics Frequency RangeUMTS FDD bands and UMTS TDD bands Channel bandwidth, 1 Resource Block=180 kHz 1.4 MHz3 MHz5 MHz10 MHz15 MHz20 MHz 6 RB15 RB25 RB50 RB 75 RB 100 RB Modulation Schemes DL: OFDMA (Orthogonal Frequency Division Multiple Access) UL: SC‐FDMA (Single Carrier Frequency Division Multiple Access) Multiple Access DL: OFDMA (Orthogonal Frequency Division Multiple Access) UL: SC‐FDMA (Single Carrier Frequency Division Multiple Access) MIMO technology DL: Wide choice of MIMO configuration options for transmit diversity, spatial multiplexing, and cyclic delay diversity (max. 4 antennas at base station and handset) UL: Multi user collaborative MIMO Peak Data RateDL: 150 Mbps (UE category 4, 2x2 MIMO, 20 MHz) 300 Mbps (UE category 5, 4x4 MIMO, 20 MHz) UL: 75 Mbps (20 MHz)

24 LTE QoS Architecture LTE architecture supports hard QoS, with end-to-end quality of service and guaranteed bit rate (GBR) for radio bearers. Just as Ethernet and the internet have different types of QoS, for example, various levels of QoS can be applied to LTE traffic for different applications. Because the LTE MAC is fully scheduled, QoS is a natural fit Evolved Packet System (EPS) bearers provide one-to-one correspondence with RLC radio bearers and provide support for Traffic Flow Templates (TFT). There are four types of EPS bearers GBR Bearer resources permanently allocated by admission control Non-GBR Bearer no admission control Dedicated Bearer associated with specific TFT (GBR or non-GBR) Default Bearer Non GBR, catch-all for unassigned traffic

Advantages of LTE

3GPP Release 8 - Freeze date 2008 Release 8 introduced LTE for the first time, with a completely new radio interface and core network, enabling substantially improved data performance compared with previous systems Highlights included: –latency down to 10ms – up to 300Mbit/s downlink and 75Mbit/s uplink –implementation in bandwidths of 1.4, 3,5, 10, 15 or 20MHz, to allow for different deployment scenarios –orthogonal frequency domain multiple access (OFDMA) downlink –single-carrier frequency domain multiple access (SC-FDMA) uplink –multiple input multiple output (MIMO) antennas –flat radio network architecture, with no equivalent to the GSM BSC or UMTS RNC, and functionality distributed among the base stations (eNodeBs) –all IP core network, the System Architecture Evolution (SAE).

3GPP Release 9 Freeze date 2009 Release 9 brought a number of refinements to features introduced in Release 8, along with new developments to the network architecture and new service features. Highlights included: –introduction of LTE femtocells in the form of the Home eNodeB (HeNB) –self organizing network (SON) features, such as optimization of the random access channel –evolved multimedia broadcast and multicast service (eMBMS) for the efficient delivery of the same multimedia content to multiple destinations –location services (LCS) to pinpoint the location of a mobile device

3GPP Release 10 - Freeze Date 2011 Release 10 provided a substantial uplift to the capacity and throughput of the LTE system and also took steps to improve the system performance for mobile devices located at some distance from a base station. Notable features included: –up to 3Gbit/s downlink and 1.5Gbit/s uplink –carrier aggregation (CA), allowing the combination of up to five separate carriers to enable bandwidths up to 100MHz –higher order MIMO antenna configurations up to 8×8 downlink and 4×4 uplink –relay nodes to support Heterogeneous Networks (“HetNets”) containing a wide variety of cell sizes –enhanced inter-cell interference coordination (eICIC) to improve performance towards the edge of cells.

3GPP Release 11 -Freeze Date 2013 Release 11 will build on the platform of Release 10 with a number of refinements to existing capabilities Notable features included: –up to 3Gbit/s downlink and 1.5Gbit/s uplink –enhancements to Carrier Aggregation, MIMO, relay nodes and eICIC –introduction of new frequency bands –coordinated multipoint transmission and reception to enable simultaneous communication with multiple cells –advanced receivers

3GPP Release 12 - Freeze Date 2014 Potential features for Release 12 were discussed at a 3GPP workshop in Slovenia in June A strong requirement was the need to support the rapid increase in mobile data usage, but other items included the efficient support of diverse applications while ensuring a high quality user experience Some of the candidates for Release 12 included: –inter-site carrier aggregation, to mix and match the capabilities and backhaul of adjacent cells – Enhanced small cells for LTE, introducing a number of features to improve the support of HetNets –new antenna techniques and advanced receivers to maximize the potential of large cells –interworking between LTE and WiFi or HSPDA –further developments of previous technologies.

31 LTE Network Architecture

10 LTE Network Architecture Contd..... The high-level network architecture of LTE is comprised of following three main components The User Equipment (UE). The Evolved UMTS Terrestrial Radio Access Network (E-UTRAN). The Evolved Packet Core (EPC).

33 UE(User Equipment) The mobile equipment comprised of the following important modules Mobile Termination (MT): This handles all the communication functions. Terminal Equipment (TE): This terminates the data streams. Universal Integrated Circuit Card (UICC): This is also known as the SIM card for LTE equipment. It runs an application known as the Universal Subscriber Identity Module (USIM). A USIM stores user-specific data very similar to 3G SIM card. This keeps information about the user's phone number, home network identity and security keys etc. Fig: User Equipment

UE(User Equipment) Identifiers IMSI - Mobile Subscriber Identity GUTI- Globally Unique Temporary Identity S-TMSI - Short Temporary Mobile Subscriber Identity SIM - user’s Subscriber Identity Module

35 The E-UTRAN(The Access Network)

36 Access Network Contd Evolved Node B (eNB) Functionalities: -- Resource management (allocation and HO) -- Admission control -- Application of negotiated UL QoS -- Cell information broadcast -- ciphering/deciphering of user and control plane data

E-UTRAN Identifiers Cell ID: The Cell ID provides a 28 bit cell label that is unique within the PLMN. The cell ID is broadcast over the air in System Information Block Type 1. eNB ID: The eNB ID identifies the eNB cell site E-UTRAN Cell Global Identifier (ECGI): The ECGI provides a global unique cell identifier, constructed from the PLMN ID and the Cell ID. Physical Cell ID (PCI): The PCI identifies the cell from a Physical Layer perspective, allowing the UEs to differentiate the Downlink signals from different cells.

38 The Evolved Packet Core (EPC) (The core network)

Core network cont… Mobility Management Entity : key control-node for the LTE access network. Functionalities: -- Idle mode UE tracking and paging procedure including retransmissions -- Bearer activation/deactivation process and choice of the SGW for a UE at the initial attach and at time of intra-LTE handover involving Core Network (CN) node relocation -- Authentication of users : it checks the authorization of the UE to camp on the service provider’s Public Land Mobile Network (PLMN) -- Control plane function for mobility between LTE and 2G/3G access

Core network cont… Serving Gateway Functionalities: -- Routing and forwarding user data packets -- Acts as mobility anchor for the user plane during inter-eNB handovers and for mobility between LTE and other 3GPP -- for idle state UEs, terminates the DL data path and triggers paging when DL data arrives for the UE -- performs replication of the user traffic in case of lawful interception

Core network cont… Packet Data Network Gateway Functionalities: -- provides connectivity to the UE to external packet data networks(IP addresses). A UE may have simultaneous connectivity with more than one PDN GW for accessing multiple PDNs. -- performs policy enforcement, packet filtering for each user, charging support lawful Interception and packet screening

LTE Network Interfaces

LTE Network Interfaces cont… S1-MME: This is the control plane interface between the E-UTRAN and the MME for S1AP and NAS signaling. S1-U: This reference point is based on the GTP-U protocol for sending user data packets between the E-UTRAN and S-GW. S11: This the control plane interface for bearer management and mobility control signaling between the MME and S-GW. S5/S8: It supports both user data traffic and control messages. It supports mobility when the UE is assigned a new S-GW. S6a: This reference point between the MME and HSS is used for Diameter protocol to exchange AAA messages related to subscriber profiles, authentication, security and location updates

LTE Network Interfaces cont…. Gx: This reference point between the PCEF function in the P-GW and the PCRF is used for transmission of QoS and charging rules to the PCEF. SGi: The reference point between the P-GW and a Packet Data Network (PDN) for the exchange of IP packets. A PDN is an IP-based network. It can be an operator’s external public or private network or a services network (e.g.,IMS) Rx: The reference point between the PCRF and an Application Function (AF) in a services network for exchange of session information related to a subscriber’s application

Summary The 3GPP Long Term Evolution (LTE) represents a major advance in cellular technology. LTE is designed to meet carrier needs for high ‐ speed data and media transport as well as high ‐ capacity voice support well into the next decade. LTE is well positioned to meet the requirements of next ‐ generation mobile networks. It will enable operators to offer high performance, mass ‐ market mobile broadband services, through a combination of high bit ‐ rates and system throughput – in both the uplink and downlink – with low latency.

Summary– Cont. LTE infrastructure is designed to be as simple as possible to deploy and operate, through flexible technology that can be deployed in a wide variety of frequency bands. LTE offers scalable bandwidths, from from 1.4 MHz up to 20MHz, together with support for both FDD paired and TDD unpaired spectrum. The LTE–SAE architecture reduces the number of nodes, supports flexible network configurations and provides a high level of service availability. Furthermore, LTE–SAE will interoperate with GSM, WCDMA/HSPA, TD ‐ SCDMA and CDMA.

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