LTE Introduction and overview

LONG TERM EVOLUTION

1

Nagasai Panchakarla

Shourov Kumar Roy

Binoy Chemmagate

Karthik Budigere Ramakrishna

AGENDA

LTE Features

3GPP Standards

LTE Key Technologies

LTE Network Architecture

Protocol Architecture

Quality of Service

Security

Roaming Architecture

Connection Management

Future of LTE and Deployments2

LTE INTRODUCTION

All IP network

High Data rates

Low latency

Reduced cost per bit

Flat network architecture

High performance radio interface

Keeping up with other technologies

Flexibility in frequency allocation

Mobility

3

3GPP 3rd Generation Partnership Project (3GPP) is a collaboration of

various telecommunication associations

Standardization body and produces Technical Specifications,

Technical Reports for 3G systems under the scope of

International Telecommunication Union (ITU)

3GPP specifications are based on evolved Global System for

Mobile Communications (GSM) specifications. Covers all GSM

(including GPRS and EDGE) and W-CDMA specifications.

Standards are structured as Releases

TSG Structure consists of GERAN(GSM EDGE ), RAN, SA

(Service & Systems Aspects), CT (Core Network & Terminals)

Different Working groups under each TSG

Following a TSG meeting revised versions of 3GPP specifications

are published. *http://www.3gpp.org/Specifications

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STANDARD RELEASES

2005/6-HSDPA2007/8-HSUPA

. . . . .

WCDMA

TD-SCDMA

HSDPA/HSUPA

TD-HSDPA

HSPA+

TD-HSUPA

LTE and HSPA+

TD-LTE and TD-HSPA+

LTE Advanced

FDD Evolution

TDD Evolution

3GPP Release

App year of n/w rollout

Release 99/4

2003/4

3GPP Study Initiated2008/9 2009/10

Release 5/6 Release 7 Release 8

The standardization process for LTE began at 3GPP Toronto workshop, 2004.

Subsequently in December 2004, 3GPP started study to develop framework for evolution to achieve high data rates for both uplink and downlink transmissions, low latency

The target was to have data rates three to four times of Release 6 HSDPA levels and two to three times of HSUPA levels.

In 2007, E UTRA (evolved UTRA) was approved from study stage to first technical specifications.

The first LTE base specifications are specified in 3GPP Release 8, December 2008.5

STANDARD RELEASES

HSDPA

UL: 384 kbps

DL: 14.4 Mbps

HSDPA/HSUPA

UL: 5.76 Mbps

DL: 14.4 Mbps

HSPA+

UL: 11.5 Mbps

DL: 28 Mbps

LTE

UL: 75 Mbps

DL: 100 Mbps

Rel 8

First Release Standard for LTE

Dec 2008

Rel 9

2nd Release 2009

Rel 10

LTE Advanced

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LTE 3GPP REL 8 OVERVIEW

UL: SC-FDMA

DL: OFDMA

Bandwidth: 1.4,3,5,10,15,20 MHz

Modulation: QPSK, 16QAM,64QAM

Subcarrier spacing: 1.5 KHz

Increased spectral efficiency over Release 6 HSPA by a factor of

two to four

Operation in both TDD and FDD modes

Coexisting with earlier 3GPP technologies

Optimized performance for 0-15 kmph, high performance for

upto 120 kmph and establish communication upto 350 kmph

Simplified architecture

Interworking with other systems7

E-UTRA OPERATING BANDSE-UTRA

Operating

Band

Uplink (UL) operating band

BS receive

UE transmit

Downlink (DL) operating band

BS transmit

UE receive

Duplex Mode

FUL_low – FUL_high FDL_low – FDL_high

1 1920 MHz – 1980 MHz 2110 MHz – 2170 MHz FDD

2 1850 MHz – 1910 MHz 1930 MHz – 1990 MHz FDD

3 1710 MHz – 1785 MHz 1805 MHz – 1880 MHz FDD

4 1710 MHz – 1755 MHz 2110 MHz – 2155 MHz FDD

5 824 MHz – 849 MHz 869 MHz – 894MHz FDD

61 830 MHz – 840 MHz 875 MHz – 885 MHz FDD

7 2500 MHz – 2570 MHz 2620 MHz – 2690 MHz FDD

8 880 MHz – 915 MHz 925 MHz – 960 MHz FDD

9 1749.9 MHz – 1784.9 MHz 1844.9 MHz – 1879.9 MHz FDD

10 1710 MHz – 1770 MHz 2110 MHz – 2170 MHz FDD

11 1427.9 MHz – 1447.9 MHz 1475.9 MHz – 1495.9 MHz FDD

12 698 MHz – 716 MHz 728 MHz – 746 MHz FDD

13 777 MHz – 787 MHz 746 MHz – 756 MHz FDD

14 788 MHz – 798 MHz 758 MHz – 768 MHz FDD

15 Reserved Reserved FDD

16 Reserved Reserved FDD

17 704 MHz – 716 MHz 734 MHz – 746 MHz FDD

18 815 MHz – 830 MHz 860 MHz – 875 MHz FDD

19 830 MHz – 845 MHz 875 MHz – 890 MHz FDD

20 832 MHz – 862 MHz 791 MHz – 821 MHz FDD

21 1447.9 MHz – 1462.9 MHz 1495.9 MHz – 1510.9 MHz FDD

...

33 1900 MHz – 1920 MHz 1900 MHz – 1920 MHz TDD

34 2010 MHz – 2025 MHz 2010 MHz – 2025 MHz TDD

35 1850 MHz – 1910 MHz 1850 MHz – 1910 MHz TDD

36 1930 MHz – 1990 MHz 1930 MHz – 1990 MHz TDD

37 1910 MHz – 1930 MHz 1910 MHz – 1930 MHz TDD

38 2570 MHz – 2620 MHz 2570 MHz – 2620 MHz TDD

39 1880 MHz – 1920 MHz 1880 MHz – 1920 MHz TDD

40 2300 MHz – 2400 MHz 2300 MHz – 2400 MHz TDD

Note 1: Band 6 is not applicable

• Release 9Technical Specification 3GPP TS 36.101 V9.3.0 (2010-03)

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LTE LICENSING

First come first seerved

Beauty contest (comparative bidding)

Lottery

Auction (competitive bidding)

Recomendations for LTE

Beauty contest and auction are best suited.

Commitments concerning coverage.

Roll out speed.

Financial capacity.

Expertise.

Resource sharing.

Nature of licensing and spectrum pricing.

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LTE LICENSING

Germany’s LTE auction begins on Monday, April 12, 2010

800MHz, 1.8GHz, 2GHz and 2.6GHz are the four different bands of spectrum offered

The auction has been declared as one of its kind in Europe paving way for other such auctions in the continent.

Source: http://wirelessfederation.com/news/24351-germany%E2%80%99s-lte-auction-begins/

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LTE KEY TECHNOLOGIES

Radio Air Interface

Modulation and spectrum flexibility

MIMO

All IP flat networking architecture

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LTE RADIO INTERFACE

OFDMA DL and SC-FDMA UL

OFDMA has multiple orthogonal subcarriers and bandwidth can be adjustable per user

Time

SC-FDMA is similar to OFDMA and since its more power efficient, it can be used in hand held devices with battery power. Single carrier, time space multiplexing

Consumes less power for transmission

Only a contiguous set of resource blocks can be selected for a user

Fre

qu

en

cy

User 2

User 1

User 3

User 4

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MODULATION AND SPECTRUM FLEXIBILITY

For down modulation QPSK, 16QAM and 64QAM are used for payload channels (spectral efficient)

For up modulation BPSK, QPSK, 8PSK and 16QAM are used

BPSK and QPSK are used for control channels ( reliability and coverage)

Adaptive modulation and coding

180 khz resource block

All user equipments must support maximum bandwidth of 20 MHz

Increase in wider bandwidth leads to cpmplexity and high power consumption

Channel bandwidth BWChannel

[MHz]1.4 3 5 10 15 20

Resource blocks 6 15 25 50 75 100

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MIMO

• Transmission is done by converting serial bit stream into

multiple parallel sub streams and sending via multiple

antennas

• Each receiver sees the output of the channel, which is a

combination of the outputs from the transmiters, separates

the sub streams from mixed signals.

• In DL: Tx and Rx Diversity

• In UL: Rx Diversity

• Increased complexity

Tx1

Tx2

Rx1

Rx2

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ALL IP FLAT ARCHITECTURE

• Software architecture evolution

• Seamless interworking with IP based communication networks with simplified network architecture

• Multimedia and circuit calls are mainly handled through converged IMS (IP Multimedia subsystem)

core which is recently termed as VoLTE (voice over LTE)

• Supports mobility between different networks

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LTE NETWORK ARCHITECTURE

LTE encompasses the evolution of the radio access through the E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) and is accompanied by an evolution of the non-radio aspects under the term ‘System Architecture Evolution’ (SAE).

SAE includes the Evolved Packet Core (EPC)network.

Together LTE and SAE comprise the Evolved Packet System (EPS) that contains fully packet-switched core network and radio access network.

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EPS (EVOLVED PACKET SYSTEM)

EPS= Core Network (EPC) + Access Network

(AN)

EPS network is comprised of the Core Network

and the Access Network, where the core network

has many logical nodes and the Access Network

has one node named as the evolved NodeB

(eNodeB) which connects to the User Equipments

(UEs).

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EPS NETWORK ELEMENTS

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CONNECTIVITY LAYERS

Internet Connectivity Layer:

UE (User Equipment), E-UTRAN and EPC (all together the Evolved Packet System) represent the Internet Protocol Connectivity Layer. This layer is optimized only for IP based connectivity.

Services Connectivity Layer:

All services will be offered on top of IP. The Services Connectivity layer includes the operator services and internet. IMS (Internet Multimedia Sub-System) can be used in the Services Connectivity Layer to provide services on top of the IP connectivity layer.

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Figure: System Architecture of LTE Network 20

THE ACCESS NETWORK : E-UTRAN

The Access Network (E-UTRAN) simply consists

of a network of eNodeBs.

eNodeBs:

The eNodeB is a radio base station that controls all the radio related functions.

Generally the eNodeBs are distributed throughout the networks coverage area.

The eNodeB is the termination point of all the radio related protocols.

It relays the data between the radio connection and the corresponding IP based connectivity towards the EPC.

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ENODEB

Figure: Overall E-UTRAN Architecture

The eNodeBs are interconnected with each other by the interface X2.

EnodeB connects to the EPC by the interface S1. More specifically it

can be said that, EnodeB connects to the MME by means of the

S1-MME interface and to the S-GW by means of the S1-U interface.22

E-UTRAN FUNCTIONALITIES

The radio related functions for which E-UTRAN is responsible can be summarized briefly as follows,

Radio Resource Management: This includes all the functions which are related to radio bearers, such as,Radio bearer control, Radio admission control,Radio mobility control, Scheduling and dynamic allocation of resources to UEs in both uplink and downlink.

Header Compression: E-UTRAN does the compression of IP packet headers.

Security: Encryption is done when data is sent over the radio interface.

Connectivity to the EPC: This includes signaling towards the MME and the bearer path towards the S-GW.

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THE CORE NETWORK: EPC (EVOLVED

PACKET CORE)

The core network (EPC) has the following logical

nodes:

i. Mobility Management Entity (MME)

ii. Policy and Charging Resource Function (PCRF)

iii. Home Subscriber Server (HSS)

iv. Packet Data Network Gateway ( P-GW)

v. Serving Gateway (S-GW)

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EPC: MME

i. Mobility Management Entity (MME): MME is the control element in EPC that takes care of the signaling part between the Core Network and UE. MME also handles the security functions for both signaling and user data.

The functions of MME can be categorized as follows,

Functions related to bearer management: It includes the establishment, maintenance and release of the bearers.

Functions related to connection management: The establishment of the connection and security between the network and UE belong to these functions.

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EPC: PCRF

ii. Policy and Charging Resource Function

(PCRF):

It is the network element which is responsible

for policy control.

It also controls the flow-based charging

functionalities in the PCEF (Policy Control

Enforcement Function) located in the P-GW.

The information PCRF provides to the PCEF is

called the Policy and Charging Control (PCC)

rules.26

EPC: HSS

iii. Home Subscriber Server (HSS):

HSS is the repository of users’ subscription data (EPS-subscribed QoSprofile and any access restrictions for roaming etc.).

It also contains the information about the PDNs to which the user can connect.

The Authentication Center(AuC) can also be integrated with the HSS.

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EPC: P-GW

iv. Packet Data Network Gateway ( P-GW):

P-GW works as the mobility anchor point for the inter-networking with non-3GPP technologies such as CDMA 2000 and WiMAX networks.

P-GW is also responsible for the IP address allocation for the User Equipment (UE).

It does the QoS enforcement for Guaranteed Bit Rate bearers and flow based charging depending on the PCRF (Policy Control and Charging Rules Function) rules. It also performs the filtering based on TFTs (Traffic Flow Templates).

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EPC: S-GW

v. Serving Gateway (S-GW):

S-GW works as the mobility anchor for inter-

working with other 3GPP technologies such as

GPRS and UMTS.

When an UE moves between eNodeBs, S-GW

serves as the local mobility anchor for the data

bearers.

It performs some additional functions in the

visited network, such as, collecting information

(e.g. volume of data sent to or received from the

user) for charging and legal interception.29

EXAMPLE: S-GW

Figure: Architecture for 3G UMTS Internetworking 30

PROTOCOL ARCHITECTURE

Protocol stacks

User Plane Protocols

- Packet Data Convergence Protocol (PDCP)

- Radio Link Control (RLC)

- Medium Access Control (MAC)

Control Plane Protocols

- Radio Resource Control (RRC)

Figure ref- www.eventhelix.com/lte/lte-tutorials.htm

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PDCP

Processes RRC msgs in Control Plane and IP pacckets in User plane

Main functions- Header Compression

- Security functions

- Handover support

- Discard User plane data

Types of data units

- PDCP data PDU's

Used in control plane and User plane

-PDCP control PDU's

Used in feedback information in header compression and status reports in

handover

Figure ref- www.eventhelix.com/lte/lte-tutorials.htm

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PDCP FUNCTIONS(1/2))

Header Compression and decompression- Robust Header Compression (ROHC)

Main functions

- To support VOIP service as in CS-domain

- VoIP packet is 32 bytes and Ipv4(40),IPv6(60)

- After ROHC overhead is reduced to 4-6 bytes

Security

- Ciphering and Deciphering user plane and control plane data.

- Integrity protection and verification for control plane data

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PDCP FUNCTIONS(2/2)

HandoverWhen UE moves from one cell to another, Two types are seamless and lossless

Seamless handover

Reasonable loss is tolerable but not delyay eg.VoIP

Lossless handover

Loss is not tolerable, retransmission

Discard user plane data

To avoid the buffer overflow.

To prevent execessive delay.

Timer expires in transmitter for discarding data.

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RLC

Main Functions

Segmentation and Reassembly

Retransmission

Reordering (HARQ)

RLC Entities Transparent Mode RLC Entity

Unacknowledged Mode RLC Entity

Acknowledged mode RLC Entity

Figure ref- www.eventhelix.com/lte/lte-tutorials.htm

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RLC MODES(1/2)

Transparent Mode RRC msgs without RLC configuration

Not used for User plane data transmission

Unidirectional data transfer service (Receiver or Transmitter)

Unacknowledged Mode Unidirectional, delay sensitive, point-multipoint

Segmentation and Concatenation of SDU’s

Reordering of PDU’s

Duplicate detection of PDU’s

Reassembly of SDU’s

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RLC MODES(2/2)

Acknowledged modeBidirectional

Retransmission of RLC data PDU’s

Re-segementation of retransmitted RLC data PDU’s

Polling

Status Report

Status Prohibit

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MAC

Multiplexing and Demultiplexing

Amount of data to be transmitted

Size of packets to be provided

Assuring QoS

Figure ref- www.eventhelix.com/lte/lte-tutorials.htm

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MAC CHANNELS(1/2)

Two Logical channels Data transfer for RLC

Control logical channels (Control data) Broadcast Control Channel (BCCH)

Paging Control Channel (PCCH)

Common Control channel(CCCH)

Multicast Control Channel (MCCH)

Dedicated Control Channel (DCCH)

Traffic Channels Dedicated Traffic Channel (DTCH)

Multicast Traffic Channel (MTCH)

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MAC CHANNELS(2/2)

Two transport channels Data transfer for Physical layer

Downlink Transport Channels Broadcast Channel (BCH)

Downlink Shared Channel (DL-SCH)

Paging Channel (PCH)

Multicast Channel (MCH)

Uplink Transport Channels Uplink Shared Channel (UL-SCH)

Random Access Channel (RACH)

Figure ref- www.eventhelix.com/lte/lte-tutorials.htm

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MAC FUNCTIONS

Scheduling

Scheduling Information Transfer

Random Access Procedure

Uplink Timing Alignment

Discontinous Reception

Multiplexing

Channel Prioritization

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CONTROL PLANE PROTOCOLS

Radio Resource Control (RRC) Transfer of Common and dedicated NAS information, Notification

of Incoming call

Two mode of UE are RRC_IDLE and RRC_CONNECTED

Main Functions

System Information

RRC connection Control

Network Controlled inter-RAT mobility

Measurement Configuration and Reporting

Miscellaneous Functions (Dedicated NAS, UE Radio access

capability)

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RRC FUNCTIONS(1/2)

System Information Master Information Block (MIB)

System Information Block Type 1(SIB1)

System Information Block Type 2(SIB2)

SIB3-SIB8

RRC connection Control Security Activation

Connection establishment, modification and release

DRB establishment, modification and release

Mobility within LTE

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RRC FUNCTIONS(2/2)

Inter-RAT mobility Handover to LTE

Mobility from LTE

Measurement Confugurations and Reporting Measurement configuration

Measurement report triggering

Measurement reporting

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DIFFERENT TYPES OF SELECTION

PLMN Selection

Cell Selection

Cell Reselection

Measurement Rules

Frequency/RAT evaluation

Cell Ranking

Accessiblity verification

Speed dependent scaling

Cell access restrictions

Any Cell selections

Closed subscriber Group

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QUALITY OF SERVICE (QOS)

Two types of bearers Minimum GBR (VoIP)

Non-GBR (Browsing ,File download)

QCI (QoS Class Identifier)

Priority

Packet delay budget

Packet loss rate

ARP ( Allocation and Retenstion Priority )

Call admission control

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SECURITY

Ciphering (both planes) and Integrity Protection (control

plane)

Key Management

Common secret key KASME (Access Security Management Entity)

between HSS and UE

Authetication by checksums and keys (random number+ common shared

key)

Two types of keys

AS base Key KeNB and AS derived keys

NULL Ciphering algorithm for emergency calls

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ROAMING ARCHITECTURE

48

ROAMING ARCHITECTURE

Roaming is one of the powerful feature which enables the

users to access the mobile network which he is not

subscribed to(Different location).

LTE supports the roaming feature by establishing the

interface between the visited Gateway with the home PDN-

gateway. This interface is known as S8 Interface.

The S8 interface allows users to access home operators

services even from the visited network.

There is interface between the visited MME and the

HSS(Home Subscriber Serer) called S6a. This is used for

billing and updating the location of the user.

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CONNECTION MANAGEMENT

LTE State Transition

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INITIAL ATTACH

The Initial attach involves the following steps,

LTE Cell Search

Primary synchronization signal

Secondary synchronization signal

Random Access Procedures

RRC Procedures

RRC Connection Establishment

Initial Security Activation

RRC Connection Reconfiguration

Bearer Establishment

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INITIAL ATTACH PROCEDURE

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PAGING PROCEDURE

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S1 BASED HANDOVER PROCEDURE

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X2 BASED HANDOVER PROCEDURE

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DEPLOYMENT

The complete migration to LTE is expected to happen by

2015

The best optimal way of deployment is to implement LTE

for data-only services and later extend it to voice based

services.

The worlds first LTE deployment is made by Teliasonera

(December 2009) in Sweden and Norway. Ericsson is

providing the LTE solutions for it.

130 operators are committed to deploy LTE by 2015.

Some of the operators promised for LTE deployment are

AT&T, Verizon, Vodafone, DNA, Elisa KT, SKT,

NTTDocomo, ZAIN, BSNL and more ….

LTE or Wimax … wait n watch 56

FUTURE OF LTE

LTE revenues expected to be $70 billion pa and also over 100

million users by 2014 says the Juniper Research.

Main markets will be North America, Europe, Far east and china.

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LTE ADVANCED

LTE Advanced expected to fulfill the IMT advanced

requirements for the 4G technology

LTE Advanced will be included in the 3GPP release 10.

The features in LTE advanced are,

Increased data rates

Carrier aggregation

Spatial Multiplexing in antennas

Coordinated multiple transmitters and receivers

Energy Efficiency

Relay Functionality

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LTE VENDORS

LTE Solution Providers

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LTE VENDORS

• LTE Chipset Providers

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LTE DEVICES

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