E-UTRA is the

air interface The air interface, or access mode, is the communication link between the two stations in mobile or wireless communication. The air interface involves both the physical and data link layers (layer 1 and 2) of the OSI model for a connection. Physi ...

of 3rd Generation Partnership Project ( 3GPP)

Long Term Evolution In telecommunications, long-term evolution (LTE) is a standard for wireless broadband communication for mobile devices and data terminals, based on the GSM/EDGE and UMTS/HSPA standards. It improves on those standards' capacity and speed by us ...

(LTE) upgrade path for mobile networks. It is an acronym for Evolved Universal Mobile Telecommunications System (

UMTS The Universal Mobile Telecommunications System (UMTS) is a third generation mobile cellular system for networks based on the GSM standard. Developed and maintained by the 3GPP (3rd Generation Partnership Project), UMTS is a component of the In ...

) Terrestrial Radio Access, also referred to as the 3GPP work item on the Long Term Evolution (LTE)3GPP UMTS Long Term Evolution page
/ref> also known as the Evolved Universal Terrestrial Radio Access (E-UTRA) in early drafts of the 3GPP LTE specification. E-UTRAN is the initialism of Evolved UMTS Terrestrial Radio Access Network and is the combination of E-UTRA,

user equipment In the Universal Mobile Telecommunications System (UMTS) and 3GPP Long Term Evolution (LTE), user equipment (UE) is any device used directly by an end-user to communicate. It can be a hand-held telephone, a laptop computer equipped with a mobile bro ...

(UE), and E-UTRAN Node B or Evolved Node B (

eNodeB E-UTRAN Node B, also known as Evolved Node B (abbreviated as eNodeB or eNB), is the element in E-UTRA of LTE that is the evolution of the element Node B in UTRA of UMTS. It is the hardware that is connected to the mobile phone network that com ...

). It is a

radio access network A radio access network (RAN) is part of a mobile telecommunication system. It implements a radio access technology. Conceptually, it resides between a device such as a mobile phone, a computer, or any remotely controlled machine and provides co ...

(RAN) which is referred to under the name EUTRAN standard meant to be a replacement of the

and

HSDPA High Speed Packet Access (HSPA) is an amalgamation of two mobile protocols—High Speed Downlink Packet Access (HSDPA) and High Speed Uplink Packet Access (HSUPA)—that extends and improves the performance of existing 3G mobile telecommunic ...

HSUPA High Speed Packet Access (HSPA) is an amalgamation of two mobile protocols—High Speed Downlink Packet Access (HSDPA) and High Speed Uplink Packet Access (HSUPA)—that extends and improves the performance of existing 3G mobile telecommunic ...

technologies specified in 3GPP releases 5 and beyond. Unlike HSPA, LTE's E-UTRA is an entirely new air interface system, unrelated to and incompatible with

W-CDMA The Universal Mobile Telecommunications System (UMTS) is a third generation mobile cellular system for networks based on the GSM standard. Developed and maintained by the 3GPP (3rd Generation Partnership Project), UMTS is a component of the Int ...

. It provides higher data rates, lower latency and is optimized for packet data. It uses

OFDMA Orthogonal frequency-division multiple access (OFDMA) is a multi-user version of the popular orthogonal frequency-division multiplexing (OFDM) digital modulation scheme. Multiple access is achieved in OFDMA by assigning subsets of subcarriers to ...

radio-access for the downlink and

SC-FDMA Single-carrier FDMA (SC-FDMA) is a frequency-division multiple access scheme. It is also called linearly precoded OFDMA (LP-OFDMA). Like other multiple access schemes (TDMA, FDMA, CDMA, OFDMA), it deals with the assignment of multiple users to a ...

on the uplink. Trials started in 2008.

Features

EUTRAN has the following features: * Peak download rates of 299.6 Mbit/s for 4×4 antennas, and 150.8 Mbit/s for 2×2 antennas with 20 MHz of spectrum.

LTE Advanced LTE Advanced (LTE+) is a mobile communication standard and a major enhancement of the Long Term Evolution (LTE) standard. It was formally submitted as a candidate 4G to ITU-T in late 2009 as meeting the requirements of the IMT-Advanced standa ...

supports 8×8 antenna configurations with peak download rates of 2,998.6 Mbit/s in an aggregated 100 MHz channel.3GPP TS 36.306 E-UTRA User Equipment radio access capabilities
/ref> * Peak upload rates of 75.4 Mbit/s for a 20 MHz channel in the LTE standard, with up to 1,497.8 Mbit/s in an LTE Advanced 100 MHz carrier. * Low data transfer latencies (sub-5 ms latency for small IP packets in optimal conditions), lower latencies for

handover In cellular telecommunications, handover, or handoff, is the process of transferring an ongoing call or data session from one channel connected to the core network to another channel. In satellite communications it is the process of transfe ...

and connection setup time. * Support for terminals moving at up to 350 km/h or 500 km/h depending on the frequency band. * Support for both FDD and TDD duplexes as well as half-duplex FDD with the same radio access technology * Support for all frequency bands currently used by IMT systems by

ITU-R The ITU Radiocommunication Sector (ITU-R) is one of the three sectors (divisions or units) of the International Telecommunication Union (ITU) and is responsible for radio communications. Its role is to manage the international radio-frequency sp ...

. * Flexible bandwidth: 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz and 20 MHz are standardized. By comparison, UMTS uses fixed size 5 MHz chunks of spectrum. * Increased

spectral efficiency Spectral efficiency, spectrum efficiency or bandwidth efficiency refers to the information rate that can be transmitted over a given Bandwidth (signal processing), bandwidth in a specific communication system. It is a measure of how efficiently a l ...

at 2–5 times more than in 3GPP ( HSPA) release 6 * Support of cell sizes from tens of meters of radius (

femto A metric prefix is a unit prefix that precedes a basic unit of measure to indicate a multiple or submultiple of the unit. All metric prefixes used today are decadic. Each prefix has a unique symbol that is prepended to any unit symbol. The pre ...

and

picocell A picocell is a small cellular base station typically covering a small area, such as in-building (offices, shopping malls, train stations, stock exchanges, etc.), or more recently in-aircraft. In cellular networks, picocells are typically used to e ...

s) up to over 100 km radius

macrocell A macrocell or macrosite is a cell in a mobile phone network that provides radio coverage served by a high power cell site (tower, antenna or mast). Generally, macrocells provide coverage larger than microcell. The antennas for macrocells are mo ...

s * Simplified architecture: The network side of EUTRAN is composed only by the

s * Support for inter-operation with other systems (e.g.,

GSM The Global System for Mobile Communications (GSM) is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe the protocols for second-generation ( 2G) digital cellular networks used by mobile devices such ...

EDGE Edge or EDGE may refer to: Technology Computing * Edge computing, a network load-balancing system * Edge device, an entry point to a computer network * Adobe Edge, a graphical development application * Microsoft Edge, a web browser developed ...

, CDMA2000,

WiMAX Worldwide Interoperability for Microwave Access (WiMAX) is a family of wireless broadband communication standards based on the IEEE 802.16 set of standards, which provide physical layer (PHY) and media access control (MAC) options. The WiMAX ...

, etc.) * Packet-switched radio interface.

Rationale for E-UTRA

Although

, with

and

and their

evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

, deliver high data transfer rates, wireless data usage is expected to continue increasing significantly over the next few years due to the increased offering and demand of services and content on-the-move and the continued reduction of costs for the final user. This increase is expected to require not only faster networks and radio interfaces but also higher cost-efficiency than what is possible by the evolution of the current standards. Thus the 3GPP consortium set the requirements for a new radio interface (EUTRAN) and core network evolution ( System Architecture Evolution SAE) that would fulfill this need. These improvements in performance allow

wireless Wireless communication (or just wireless, when the context allows) is the transfer of information between two or more points without the use of an electrical conductor, optical fiber or other continuous guided medium for the transfer. The most ...

operators to offer ''

quadruple play In telecommunications, quadruple play or quad play is a marketing term combining the triple play service of broadband Internet access, television and telephone with wireless service provisions. This service set is also sometimes referred to as "The ...

'' services voice, high-speed interactive applications including large data transfer and

feature-rich In software, the term feature has several definitions. The Institute of Electrical and Electronics Engineers defines the term ''feature'' in IEEE 829 as " distinguishing characteristic of a software item (e.g., performance, portability, or functio ...

IPTV Internet Protocol television (IPTV) is the delivery of television content over Internet Protocol (IP) networks. This is in contrast to delivery through traditional terrestrial, satellite, and cable television formats. Unlike downloaded med ...

with full mobility. Starting with the 3GPP Release 8, E-UTRA is designed to provide a single evolution path for the

/ HSPA, CDMA2000/

EV-DO Evolution-Data Optimized (EV-DO, EVDO, etc.) is a telecommunications standard for the wireless transmission of data through radio signals, typically for broadband Internet access. EV-DO is an evolution of the CDMA2000 (IS-2000) standard which su ...

and

TD-SCDMA The Universal Mobile Telecommunications System (UMTS) is a third generation mobile cellular system for networks based on the GSM standard. Developed and maintained by the 3GPP (3rd Generation Partnership Project), UMTS is a component of the In ...

radio interfaces, providing increases in data speeds, and spectral efficiency, and allowing the provision of more functionality.

Architecture

EUTRAN consists only of eNodeBs on the network side. The eNodeB performs tasks similar to those performed by the nodeBs and RNC (radio network controller) together in UTRAN. The aim of this simplification is to reduce the latency of all radio interface operations. eNodeBs are connected to each other via the X2 interface, and they connect to the packet switched (PS) core network via the S1 interface.3GPP TS 36.300 E-UTRA Overall description
/ref>

EUTRAN protocol stack

The EUTRAN

protocol stack The protocol stack or network stack is an implementation of a computer networking protocol suite or protocol family. Some of these terms are used interchangeably but strictly speaking, the ''suite'' is the definition of the communication protoco ...

consists of: * Physical layer:3GPP TS 36.201 E-UTRA: LTE physical layer; General description
/ref> Carries all information from the MAC transport channels over the air interface. Takes care of the link adaptation (ACM),

power control Power control, broadly speaking, is the intelligent selection of transmitter power output in a communication system to achieve good performance within the system.Guowang Miao, Jens Zander, Ki Won Sung, and Ben Slimane, Fundamentals of Mobile Data ...

, cell search (for initial synchronization and handover purposes) and other measurements (inside the LTE system and between systems) for the RRC layer. * MAC:3GPP TS 36.321 E-UTRA: Access Control (MAC) protocol specification
/ref> The MAC sublayer offers a set of logical channels to the RLC sublayer that it multiplexes into the physical layer transport channels. It also manages the HARQ error correction, handles the prioritization of the logical channels for the same UE and the dynamic scheduling between UEs, etc.. * RLC:3GPP TS 36.322 E-UTRA: Radio Link Control (RLC) protocol specification
/ref> It transports the PDCP's PDUs. It can work in 3 different modes depending on the reliability provided. Depending on this mode it can provide: ARQ error correction, segmentation/concatenation of PDUs, reordering for in-sequence delivery, duplicate detection, etc... *

PDCP Packet Data Convergence Protocol (PDCP) is specified by 3GPP in TS 25.323 for UMTS, TS 36.323 for LTE and TS 38.323 for 5G. PDCP is located in the Radio Protocol Stack in the UMTS/LTE/5G air interface on top of the RLC layer. PDCP provides its ...

:3GPP TS 36.323 E-UTRA: Packet Data Convergence Protocol (PDCP) specification
/ref> For the RRC layer it provides transport of its data with ciphering and integrity protection. And for the IP layer transport of the IP packets, with ROHC header compression, ciphering, and depending on the RLC mode in-sequence delivery, duplicate detection and retransmission of its own SDUs during handover. * RRC:3GPP TS 36.331 E-UTRA: Radio Resource Control (RRC) protocol specification
/ref> Between others it takes care of: the broadcast system information related to the access stratum and transport of the non-access stratum (NAS) messages, paging, establishment and release of the RRC connection, security key management, handover, UE measurements related to inter-system (inter-RAT) mobility, QoS, etc.. Interfacing layers to the EUTRAN protocol stack: * NAS:3GPP TS 24.301 Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3
/ref> Protocol between the UE and the MME on the network side (outside of EUTRAN). Between others performs authentication of the UE, security control and generates part of the paging messages. * IP

Physical layer (L1) design

E-UTRA uses orthogonal frequency-division multiplexing (OFDM),

multiple-input multiple-output In radio, multiple-input and multiple-output, or MIMO (), is a method for multiplying the capacity of a radio link using multiple transmission and receiving antennas to exploit multipath propagation. MIMO has become an essential element of wir ...

(MIMO) antenna technology depending on the terminal category and can use as well

beamforming Beamforming or spatial filtering is a signal processing technique used in sensor arrays for directional signal transmission or reception. This is achieved by combining elements in an antenna array in such a way that signals at particular angles e ...

for the downlink to support more users, higher data rates and lower processing power required on each handset. In the uplink LTE uses both

and a precoded version of OFDM called Single-Carrier Frequency-Division Multiple Access (SC-FDMA) depending on the channel. This is to compensate for a drawback with normal OFDM, which has a very high peak-to-average power ratio (PAPR). High PAPR requires more expensive and inefficient power amplifiers with high requirements on linearity, which increases the cost of the terminal and drains the battery faster. For the uplink, in release 8 and 9 multi user MIMO / Spatial division multiple access (SDMA) is supported; release 10 introduces also

SU-MIMO In radio, multiple-input and multiple-output, or MIMO (), is a method for multiplying the capacity of a radio link using multiple transmission and receiving antennas to exploit multipath propagation. MIMO has become an essential element of wi ...

. In both OFDM and SC-FDMA transmission modes a

cyclic prefix In telecommunications, the term cyclic prefix refers to the prefixing of a symbol, with a repetition of the end. The receiver is typically configured to discard the cyclic prefix samples, but the cyclic prefix serves two purposes: * It provides a ...

is appended to the transmitted symbols. Two different lengths of the cyclic prefix are available to support different channel spreads due to the cell size and propagation environment. These are a normal cyclic prefix of 4.7 μs, and an extended cyclic prefix of 16.6 μs. Resource-Block LTE OFDMA

LTE supports both

Frequency-division duplex A duplex communication system is a point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions. Duplex systems are employed in many communications networks, either to allow ...

(FDD) and

Time-division duplex A duplex communication system is a point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions. Duplex systems are employed in many communications networks, either to allow ...

(TDD) modes. While FDD makes use of paired spectra for UL and DL transmission separated by a duplex frequency gap, TDD splits one frequency carrier into alternating time periods for transmission from the base station to the terminal and vice versa. Both modes have their own frame structure within LTE and these are aligned with each other meaning that similar hardware can be used in the base stations and terminals to allow for economy of scale. The TDD mode in LTE is aligned with

as well allowing for coexistence. Single chipsets are available which support both TDD-LTE and FDD-LTE operating modes.

Frames and resource blocks

The LTE transmission is structured in the time domain in radio frames. Each of these radio frames is 10 ms long and consists of 10 sub frames of 1 ms each. For non-

Multimedia Broadcast Multicast Service Multimedia Broadcast Multicast Services (MBMS) is a point-to-multipoint interface specification for existing 3GPP cellular networks, which is designed to provide efficient delivery of broadcast and multicast services, both within a cell as well ...

(MBMS) subframes, the

sub-carrier spacing in the frequency domain is 15 kHz. Twelve of these sub-carriers together allocated during a 0.5 ms timeslot are called a resource block.TS 36.211 rel.11, LTE, Evolved Universal Terrestrial Radio Access, Physical channels and modulation - chapters 5.2.3 and 6.2.3: Resource blocks
etsi.org, January 2014 A LTE terminal can be allocated, in the downlink or uplink, a minimum of 2 resources blocks during 1 subframe (1 ms).

Encoding

All L1 transport data is encoded using

turbo coding In information theory, turbo codes (originally in French ''Turbocodes'') are a class of high-performance forward error correction (FEC) codes developed around 1990–91, but first published in 1993. They were the first practical codes to closely ...

and a contention-free quadratic permutation polynomial (QPP) turbo code internal

interleaver In computing, telecommunication, information theory, and coding theory, an error correction code, sometimes error correcting code, (ECC) is used for controlling errors in data over unreliable or noisy communication channels. The central idea is ...

.3GPP TS 36.212 E-UTRA Multiplexing and channel coding
/ref> L1

HARQ Hybrid automatic repeat request (hybrid ARQ or HARQ) is a combination of high-rate forward error correction (FEC) and automatic repeat request (ARQ) error-control. In standard ARQ, redundant bits are added to data to be transmitted using an er ...

with 8 (FDD) or up to 15 (TDD) processes is used for the downlink and up to 8 processes for the UL

EUTRAN physical channels and signals

Downlink (DL)

In the downlink there are several physical channels: * The Physical Downlink Control Channel (PDCCH) carries between others the downlink allocation information, uplink allocation grants for the terminal/UE. * The Physical Control Format Indicator Channel (PCFICH) used to signal CFI (control format indicator). * The Physical Hybrid ARQ Indicator Channel (PHICH) used to carry the acknowledges from the uplink transmissions. * The Physical Downlink Shared Channel (PDSCH) is used for L1 transport data transmission. Supported modulation formats on the PDSCH are

QPSK Phase-shift keying (PSK) is a digital modulation process which conveys data by changing (modulating) the phase of a constant frequency reference signal (the carrier wave). The modulation is accomplished by varying the sine and cosine inputs at ...

, 16QAM and

64QAM Quadrature amplitude modulation (QAM) is the name of a family of digital modulation methods and a related family of analog modulation methods widely used in modern telecommunications to transmit information. It conveys two analog message signal ...

. * The Physical Multicast Channel (PMCH) is used for broadcast transmission using a Single Frequency Network * The Physical Broadcast Channel (PBCH) is used to broadcast the basic system information within the cell And the following signals: * The synchronization signals (PSS and SSS) are meant for the UE to discover the LTE cell and do the initial synchronization. * The reference signals (cell specific, MBSFN, and UE specific) are used by the UE to estimate the DL channel. * Positioning reference signals (PRS), added in release 9, meant to be used by the UE for

OTDOA OTDOA (Observed Time Difference Of Arrival) is a positioning feature introduced in rel9 E-UTRA ( LTE radio). It's a multilateration method in which the User Equipment (UE) measures the time difference between some specific signals from several eNo ...

positioning (a type of

multilateration Trilateration is the use of distances (or "ranges") for determining the unknown position coordinates of a point of interest, often around Earth (geopositioning). When more than three distances are involved, it may be called multilateration, for e ...

)

Uplink (UL)

In the uplink there are three physical channels: * Physical Random Access Channel (PRACH) is used for initial access and when the UE loses its uplink synchronization, * Physical Uplink Shared Channel (PUSCH) carries the L1 UL transport data together with control information. Supported modulation formats on the PUSCH are

, 16QAM and depending on the

User Equipment (UE) categories

3GPP Release 8 defines five LTE user equipment categories depending on maximum peak data rate and MIMO capabilities support. With 3GPP Release 10, which is referred to as

, three new categories have been introduced. Followed by four more with Release 11, two more with Release 14, and five more with Release 15. Note: Maximum data rates shown are for 20 MHz of channel bandwidth. Categories 6 and above include data rates from combining multiple 20 MHz channels. Maximum data rates will be lower if less bandwidth is utilized. Note: These are L1 transport data rates not including the different protocol layers overhead. Depending on cell

bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...

, cell load (number of simultaneous users), network configuration, the performance of the user equipment used, propagation conditions, etc. practical data rates will vary. Note: The 3.0 Gbit/s / 1.5 Gbit/s data rate specified as Category 8 is near the peak aggregate data rate for a base station sector. A more realistic maximum data rate for a single user is 1.2 Gbit/s (downlink) and 600 Mbit/s (uplink). Nokia Siemens Networks has demonstrated downlink speeds of 1.4 Gbit/s using 100 MHz of aggregated spectrum.

EUTRAN releases

As the rest of the 3GPP standard parts E-UTRA is structured in releases. * Release 8, frozen in 2008, specified the first LTE standard * Release 9, frozen in 2009, included some additions to the physical layer like dual layer (MIMO) beam-forming transmission or positioning support * Release 10, frozen in 2011, introduces to the standard several

features like carrier aggregation, uplink

or relays, aiming to a considerable L1 peak data rate increase. All LTE releases have been designed so far keeping backward compatibility in mind. That is, a release 8 compliant terminal will work in a release 10 network, while release 10 terminals would be able to use its extra functionality.

Frequency bands and channel bandwidths

Deployments by region

Technology demos

* In September 2007, NTT Docomo demonstrated E-UTRA data rates of 200 Mbit/s with power consumption below 100 mW during the test. * In April 2008, LG and Nortel demonstrated E-UTRA data rates of 50 Mbit/s while travelling at 110 km/h. * February 15, 2008 Skyworks Solutions has released a front-end module for E-UTRAN.

References

External links

EARFCN calculator and band reference

S1-AP procedures E-RAB Setup,modify and release

3GPP Long Term Evolution page

LTE 3GPP Encyclopedia

3G Americas - UMTS/HSPA Speeds Up the Wireless Technology Roadmap. 3G Americas Publishes White Paper on 3GPP Release 7 to Release 8. Bellevue, WA, July 10, 2007
{{Internet Access LTE (telecommunication) Mobile telecommunications Mobile telecommunications standards Telecommunications infrastructure