E-UTRA

EUTRAN architecture as part of a LTE and SAE network

e-UTRA is the air interface of 3GPP's Long Term Evolution (LTE) upgrade path for mobile networks. It is an acronym for evolved UMTS Terrestrial Radio Access, also referred to as the 3GPP work item on the Long Term Evolution (LTE)[1] also known as the Evolved Universal Terrestrial Radio Access (E-UTRA) in early drafts of the 3GPP LTE specification.[1] E-UTRAN is the initialism of Evolved UMTS Terrestrial Radio Access Network and is the combination of E-UTRA, UEs and EnodeBs.

It is a radio access network which is referred to under the name EUTRAN standard meant to be a replacement of the UMTS and HSDPA/HSUPA 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. It provides higher data rates, lower latency and is optimized for packet data. It uses OFDMA radio-access for the downlink and SC-FDMA on the uplink. Trials started in 2008.

Features

EUTRAN has the following features:

Rationale for E-UTRA

Although UMTS, with HSDPA and HSUPA and their evolution, 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 operators to offer quadruple play services - voice, high-speed interactive applications including large data transfer and feature-rich IPTV with full mobility.

Starting with the 3GPP Release 8, e-UTRA is designed to provide a single evolution path for the GSM/EDGE, UMTS/HSPA, CDMA2000/EV-DO and TD-SCDMA 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.[3]

EUTRAN protocol stack

EUTRAN protocol stack

The EUTRAN protocol stack consist of:[3]

Interfacing layers to the EUTRAN protocol stack:

Physical layer (L1) design

E-UTRA uses orthogonal frequency-division multiplexing (OFDM), multiple-input multiple-output (MIMO) antenna technology depending on the terminal category and can use as well beamforming for the downlink to support more users, higher data rates and lower processing power required on each handset.[10]

In the uplink LTE uses both OFDMA 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 both OFDM and SC-FDMA transmission modes a cyclic prefix 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 16.6µs.

LTE Resource Block in time and frequency domains: 12 subcarriers, 0.5 ms timeslot (normal cyclic prefix).

LTE supports both Frequency-division duplex (FDD) and Time-division duplex (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 TD-SCDMA as well allowing for coexistence. Single chipsets are available which support both TDD-LTE and FDD-LTE operating modes.

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-MBMS subframes, the OFDMA 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.[11] A LTE terminal can be allocated, in the downlink or uplink, a minimum of 2 resources blocks during 1 subframe (1 ms).[12]

All L1 transport data is encoded using turbo coding and a contention-free quadratic permutation polynomial (QPP) turbo code internal interleaver.[13] L1 HARQ 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:[14]

And the following signals:

Uplink (UL)

In the uplink there are three physical channels:

And the following signals:

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 LTE Advanced, three new categories have been introduced, and four more with 3GPP Release 11.

User
equipment
Category		 Max. L1
datarate
Downlink
(Mbit/s)		 Max. number
of DL MIMO
layers		 Max. L1
datarate
Uplink
(Mbit/s)		 3GPP Release
0 1.0 1 1.0 Rel 12
1 10.3 1 5.2 Rel 8
2 51.0 2 25.5 Rel 8
3 102.0 2 51.0 Rel 8
4 150.8 2 51.0 Rel 8
5 299.6 4 75.4 Rel 8
6 301.5 2 or 4 51.0 Rel 10
7 301.5 2 or 4 102.0 Rel 10
8 2,998.6 8 1,497.8 Rel 10
9 452.2 2 or 4 51.0 Rel 11
10 452.2 2 or 4 102.0 Rel 11
11 603.0 2 or 4 51.0 Rel 11
12 603.0 2 or 4 102.0 Rel 11
13 391.7 2 or 4 150.8 Rel 12
14 3,917 8 N/A Rel 12
15 750 4 or 2 N/A Rel 12
16 979 4 or 2 N/A Rel 12

Note: Maximum datarates shown are for 20 MHz of channel bandwidth. Categories 6 and above include datarates from combining multiple 20 MHz channels. Maximum datarates 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 BW, cell load, network configuration, the performance of the UE 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).[16] Nokia Siemens Networks has demonstrated downlink speeds of 1.4 Gbit/s using 100 MHz of aggregated spectrum.[17]

EUTRAN releases

As the rest of the 3GPP standard parts E-UTRA is structured in releases.

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

See also

References

  1. 1 2 3GPP UMTS Long Term Evolution page
  2. 1 2 3GPP TS 36.306 E-UTRA User Equipment radio access capabilities
  3. 1 2 3GPP TS 36.300 E-UTRA Overall description
  4. ↑ 3GPP TS 36.201 E-UTRA: LTE physical layer; General description
  5. ↑ 3GPP TS 36.321 E-UTRA: Access Control (MAC) protocol specification
  6. ↑ 3GPP TS 36.322 E-UTRA: Radio Link Control (RLC) protocol specification
  7. ↑ 3GPP TS 36.323 E-UTRA: Packet Data Convergence Protocol (PDCP) specification
  8. ↑ 3GPP TS 36.331 E-UTRA: Radio Resource Control (RRC) protocol specification
  9. ↑ 3GPP TS 24.301 Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3
  10. ↑ http://cp.literature.agilent.com/litweb/pdf/5989-7898EN.pdf
  11. ↑ 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
  12. ↑ LTE Frame Structure and Resource Block Architecture Teletopix.org, retrieved in August 2014.
  13. ↑ 3GPP TS 36.212 E-UTRA Multiplexing and channel coding
  14. ↑ 3GPP TS 36.211 E-UTRA Physical channels and modulation
  15. ↑ Nomor Research Newsletter: LTE Random Access Channel
  16. ↑ 3GPP LTE / LTE-A Standardization: Status and Overview of Technologie, slide 16
  17. ↑ 4G speed record smashed with 1.4 Gigabits-per-second mobile call #MWC12
  18. ↑ NTT DoCoMo develops low power chip for 3G LTE handsets
  19. ↑ Nortel and LG Electronics Demo LTE at CTIA and with High Vehicle Speeds at the Wayback Machine (archived June 6, 2008)
  20. ↑ "Skyworks Rolls Out Front-End Module for 3.9G Wireless Applications. (Skyworks Solutions Inc.)" (free registration required). Wireless News. February 14, 2008. Retrieved 2008-09-14.
  21. ↑ "Wireless News Briefs - February 15, 2008". WirelessWeek. February 15, 2008. Retrieved 2008-09-14.
  22. ↑ "Skyworks Introduces Industry's First Front-End Module for 3.9G Wireless Applications". Skyworks press release (Free with registration). 11 Feb 2008. Retrieved 2008-09-14.

External links

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