lte documentation

7/31/2019 LTE Documentation

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Cairo University

Faculty of Engineering

Credit Hour Programs

Senior-2

ELC N406 | Communications-3

LTE (Long Term Evolution)

Prepared by:

Eman Alaa

Christine Onsy

Yasmin Afify


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Table of contents:

Introduction 3

Consumer and industry trends4

LTE proposition... ..4

LTE challenges. ..5

LTE benefits... .6

LTE key features. ..8

LTE Modulation schemes ..12

LTE network architecture ..13

Comparisons between LTE and HSPA+17

Comparisons between LTE and WiMax19

Summary 22

List of figures....23

References.24


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Introduction:

LTE is a standard for wireless communication of high-speed data for mobile phones and

data terminals. It is based on the GSM/EDGE and UMTS/HSPA network technologies,

increasing the capacity and speed using new modulation techniques.

The standard is developed by the 3GPP (3rd Generation Partnership Project).The world's

first publicly available LTE service was launched by Telia Sonera in the Scandinavian

capitals Stockholm and Oslo on 14 December 2009.

LTE is the natural upgrade path for carriers with GSM/UMTS networks, but even

CDMA holdouts such as Verizon in North America and au by KDDI in Japan have

announced that they will migrate to LTE in the future.

LTE is therefore anticipated to become the first truly global mobile phone standard.

Although commonly referred to as a type of 4G wireless service, LTE release 8 currently

in uses does not satisfy the requirements set forth by the ITU-R organization

(International Telecommunication Union Radio Communication).

Future releases of LTE (referred to as LTE Advanced) are expected to satisfy the

requirements to be considered 4G.


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Consumer and industry trends:

End users increase usage of advanced communication services andapplications like media downloads, VOIP, video streaming, online

gaming, social networking, Email and search.

Accelerating the delivery of personal media experience ( broadbandeverywhere, optimized networks)

LTE Makes On-Demand Possible (Entertainmentand productivity, Personal broadband on the go, Fashionable devices

working across technologies.

LTE Proposition:

1. Broadband experience everywhere: faster more responsive

2. Improved business proposition: Lower cost Added capacity Flexible Global


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LTE challenges:

1. The user expectation

Best price Transparent flat rate Full internet Click-bang responsiveness

2. Operators challenges Reduce cost per bit Provide high data rate Provide low latency

Figure (1)


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LTE Benefits:

1. Flexible Spectrum usage possible with LTE

- It supports paired and unpaired frequency spectrum.- The possibility of allocating spectrum bandwidth with variable size

from 1.4 to 20 MHZ. while in WCDMA & HSPA is always 5 MHZand fixed.

- A small channel bandwidth is more beneficial for mobile operators.On the other hand a large bandwidth is required if large peak data

rates to be supported.

2. Higher data rates

- At 20 MHZ it has beenreached to 150 Mbps

using 2x2 MIMO, and

300 Mbps using 4x4

MIMO ( DL) , and 75

Mbps (UL).


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3. Simple Architecture:

- LTE has a much simpler and relatively flat architecture comparedto the legacy UMTS network in HSPA+

4. Lower Cost:- High reuse of existing spectrum assets, which means that(LTE will allow operators to generate fresh sources of value from their

existing network investments while enjoying the significant economies of

scale that flows from the participation in the world's biggest and most

successful family of evolving cellular system)


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5. Ultra low latency:A) Round Trip Times:

LTE enables round trip times (RTT) of less than 20 ms. The round trip

time or user plane latency is the time it takes for information to travel

from the mobile terminal to the destination in the network and back to

the terminal.

B) Control Plane Latency:

Also the control plane latency - the time needed to allocate transport

resources - is important. The requirement for the control plane latency

in LTE is less than 100 ms.

LTE Key features:

1-Evolved NodeB:

- No RNC is provided anymore.- The evolved Node only takes over all radio management functionality.- This will make radio management faster and hopefully simplify Network

architecture

- The eNodeB decides - again on a sub frame-to-sub frame basiswhichmodulation scheme, coding rate, and power level should be applied in

uplink and downlink. Adaptive modulation and coding has already been

implemented in High-Speed Packet Access (HSPA) systems.


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2- IP Transport layer:

- EUTRAN exclusively uses IP as transport layer.

3- 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

4-HARQ: Hybrid Automatic repeat Request

- HARQ especially increases the performance (delay and throughput)for cell edge users.

- HARQ simply implements a retransmission protocol on layer 1/2 thatallows sending retransmitted blocks with different coding than the 1st

one.

5- QOS Awareness:

- The scheduler must handle and distinguish different quality of service- Otherwise real time services would not be possible via EUTRAN.- The system provides the possibility for differentiated service.

6-Self Configuration:

- Possibility to let Evolved Node configure themselves.- But it will not completely substitute the manual configuration and

optimization.


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7-Packet Switched Domain Only:

- No circuit switched domain is provided.- If CS applications are required, they must be implemented via IP.

8-Non 3GPP Access:

- The EPC will be prepared also to be used by non3GPP accessnetworks (e.g. LAN, WLAN, Wi-MAX, etc.)

- This will provide true convergence of different packet radio accesssystem.

9-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 Spectralefficiency.

The LTE radio interface initially supports 2x2 (and later 4x4) MultipleInput Multiple Output (MIMO) transmission in the downlink. 2x2

MIMO employs two transmit antennas at the eNodeB side and two

receive antennas at the mobile terminal side of the transmission link.


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There are actually two kinds of MIMO techniques:

Multi stream transmission (also known as spatial multiplexing)MIMO

Diversity (or space-time coding) MIMO.Multi stream Diversity

Each transmit antenna transmits a

different data stream

Each transmit antenna transmits the

same data stream

Although the data streams are

transmitted simultaneously at the

same frequency, the receiver can

nevertheless detect the different

streams received via different

antennas - hence the name spatial

multiplexing

In the special case of beam forming,

the same data stream is transmitted,

but with a different phase shift in

each transmit antenna, thus

effectively sending the transmit

signal in a certain direction

Increases the peak data rate over

the radio link. For instance, 4x4

MIMO effectively increases thepeak data rate by a factor of four

Does not increase the peak data rate

over the radio link, but is beneficial

in low SNIR conditions


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LTE Modulation Schemes:

1. OFDM- LTE uses OFDM for the DLthat is, from the base station to the

terminal.

- OFDM meets the LTE requirement for spectrum flexibility andenables costefficient solutions for very wide carriers with high peak

rates

- The basic LTE downlink physical resource can be seen as atimefrequency grid. In the frequency domain, the spacing between

the subcarriers, f, is 15kHz.

- In OFDMA, each subcarrier only carries information related to onespecific symbol.

- The Signals are orthogonal to each other at their peaks to guaranteethe maximum power and least interference.

2. SC-FDMA- Each subcarrier contains information of ALL transmitted symbols.- Uplink multiplexing-

Lower Peak to Average Power Ratio (PARR)Less Power Consumption

Less expensive RF amplifiers in the terminal


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LTE Network Architecture:

- In contrast to the circuit-switched model of previous cellular systems,Long Term Evolution (LTE) has been designed to support only packet-

switched services.

- It aims to provide seamless Internet Protocol (IP) connectivity betweenuser equipment (UE) and the packet data network (PDN),

Without any disruption to the end users applications during mobility.

- While the term LTE encompasses the evolution of the UniversalMobile Telecommunications System (UMTS) radio access through the

Evolved UTRAN (E-UTRAN), it is accompanied by an evolution of the

non-radio aspects under the term System Architecture Evolution

(SAE), which includes the Evolved Packet Core (EPC) network.

Together LTE and SAE comprise the Evolved Packet System (EPS).

- EPS uses the concept of EPS bearers to route IP traffic from a gateway inthe PDN to the UE.

- A bearer is an IP packet flow with a defined quality of service (QoS)between the gateway and the UE.

- The E-UTRAN and EPC together set up and release bearers as requiredby applications.

- EPS provides the user with IP connectivity to a PDN for accessing theInternet, as well as for running services such as Voice over IP (VoIP). An

EPS bearer is typically associated with a QoS. Multiple bearers can beestablished for a user in order to provide different QoS streams or

connectivity to different PDNs. For example, a user might be engaged in

a voice (VoIP) call while at the same time performing web browsing or

FTP download. A VoIP bearer would provide the necessary QoS for the

voice call, while a best-effort bearer would be suitable for the web

browsing or FTP session.

- The network must also provide sufficient security and privacy for theuser and protection for the network against fraudulent use.


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Figure (2)

The core network:

The core network (called EPC in SAE) is responsible for the overall control

of the UE and establishment of the bearers. The main logical nodes of theEPC are:

PDN Gateway (P-GW)

Serving Gateway (S-GW)

Mobility Management Entity (MME)

In addition to these nodes, EPC also includes other logical nodes and

functions such as the Home Subscriber Server (HSS) and the Policy Control

and Charging Rules Function (PCRF). Since the EPS only provides a bearer

path of a certain QoS, control of multimedia applications such as VoIP is

provided by the IP Multimedia Subsystem (IMS), which is considered to be

outside the EPS itself.


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The logical CN nodes:

PCRFThe Policy Control and Charging Rules Function is responsiblefor policy control decision-making, as well as for controlling the flow-based

charging functionalities in the Policy Control Enforcement Function (PCEF),

which resides in the P-GW. The PCRF provides the QoS authorization (QoS

class identifier [QCI] and bit rates) that decides how a certain data flow will

be treated in the PCEF and ensures that this is in accordance with the users

subscription profile.

HSSThe Home Subscriber Server contains users SAE subscription datasuch as the EPS-subscribed QoS profile and any access restrictions for

roaming. It also holds information about the PDNs to which the user can

connect. This could be in the form of an access point name (APN) (which is

a label according to DNS naming conventions describing the access point tothe PDN) or a PDN address (indicating subscribed IP address (es)). In

addition the HSS holds dynamic information such as the identity of the

MME to which the user is currently attached or registered. The HSS may

also integrate the authentication center (AUC), which generates the vectors

for authentication and security keys.

P-GWThe PDN Gateway is responsible for IP address allocation for theUE, as well as QoS enforcement and flow-based charging according to rules

from the PCRF. It is responsible for the filtering of downlink user IP packets

into the different QoS-based bearers. This is performed based on Traffic

Flow Templates (TFTs). The P-GW performs QoS enforcement for

guaranteed bit rate (GBR) bearers. It also serves as the mobility anchor for

interworking with non-3GPP technologies such as CDMA2000 and WiMAX

networks.

S-GWAll user IP packets are transferred through the Serving Gateway,

which serves as the local mobility anchor for the data bearers when the UE

moves between eNodeBs. It also retains the information about the bearers

when the UE is in the idle state (known as EPS Connection ManagementIDLE [ECM-IDLE]) and temporarily buffers downlink data while theMME initiates paging of the UE to reestablish the bearers. In addition, the S-

GW performs some administrative functions in the visited network such as

collecting information for charging (for example, the volume of data sent to

or received from the user) and lawful interception. It also serves as the


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mobility anchor for interworking with other 3GPP technologies such as

general packet radio service (GPRS) and UMTS.

MMEThe Mobility Management Entity (MME) is the control node thatprocesses the signaling between the UE and the CN. The protocols running

between the UE and the CN are known as the Non Access Stratum (NAS)

protocols.

The main functions supported by the MME can be classified as:

Functions related to bearer management This includes theestablishment, maintenance and release of the bearers and is handled by the

session management layer in the NAS protocol.

Functions related to connection managementThis includes theestablishment of the connection and security between the network and UE

and is handled by the connection or mobility management layer in the NAS

protocol layer.


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Comparison between LTE and HSPA+:

Advantages of LTE over HSPA+:

Flexible Spectrum usage possible with LTE: LTE will be the same

whether the bandwidth available is 5MHz or 20MHz. Of course the

data rate will increase when the BW is increased. With HSPA+ only

5MHz bandwidths is possible. Similarly with HSPA+ only FDD mode

of operation is possible whereas with LTE FDD or TDD mode is

possible.

Spectrum Efficiency: Better spectrum efficiency, by a factor of 2 atleast over HSPA+

Simpler Architecture: LTE has a much simpler and relatively flat

architecture compared to the legacy UMTS network in HSPA+

Higher Data Rates: LTE gives DL data rates of 144Mbps and UL of57Mbps. HSPA+ gives 42Mbps in DL and 11Mbps in UL

Ultra Low Latency: 10ms instead of 50ms for HSPA+

Short TTI: 0.5ms instead of 2ms for HSPA+


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Advantages of HSPA+ over LTE

Will be ready much before LTE: HSPA+ technology should be

available in Q1 2009 whereas the earliest with LTE would be

sometime in 2010.

Much less investment in infrastructure: Since HSPA+ is evolution of

HSPA which is already being deployed; it would be easier and less

costly to upgrade. With LTE since its based on OFDM a lot of newcomponents will be required. Also in case of LTE the number of

components is reduced but since they work in a different way, new

components will be required.

Figure (3)

Figure (4)


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Comparison between LTE and WiMAX:

WiMax is in the market while Long Term Evolution is still inthe labs...So, in this point, WiMax has a clear time

advantage over LTE: WiMax is present nowadays in

numerous countries around the world.

Figure (5)

There is a good difference in the latency of WiMax andLTE, and some "real time" multimedia services will get

benefit of this.

Figure (6)

LTE provides FULL mobility. While WiMax needs amobile target with a speed lower than 120 km/h, LTE stilloperates with a target up to 350 km/h.

LTE supports handover and roaming with the3GGP mobile networks. However, these services are not

easy to achieve with WiMax.
http://4gwirelessjobs.com/articles/article-detail.php?Analysis-WiMax-&-LTE&Arid=MTA5&Auid=OTU=http://4gwirelessjobs.com/articles/article-detail.php?Analysis-WiMax-&-LTE&Arid=MTA5&Auid=OTU=


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It seems that Intel will integrate WIMAX in its newdevices...It ensures a good number of WiMax devices in the

market by default, which is very good to expand

the potential market of WiMax.

LTE, like GSM, needs a SIM card to operate. The use of aSIM card has its advantages and also its disadvantages.

On the one hand, with LTE, the use of a SIM card ismandatory for the users and that is a requirement for them,

which is not good because the users want things easy, so

the fewer requirements needed the better.

On the other hand, the use of SIM card makes easier toprovide some services like roaming, which is a key service

nowadays. Identifying subscribers with a SIM makes thingseasier to the carrier.

There are plenty of telecom carriers around the world thatare going to LTE instead of WiMax. Most of them have a

GSM infrastructure already deployed, so LTE is a logic

step in their evolution to the next 4G (or 3,9G)

Some examples of this are: Biggest carriers in USA: AT&T, Verizon.

Vodafone China Mobile

DoCoMo (2010-2011).

Others: KDDI, Telstra, Telecom Italia, China Telecom, Orange,

and T-Mobile.

The initial costs of WiMax are lower when the operators donot have any 2G3G equipment, so WiMax could be agood option because the CAPEX of WiMax are lower than

the CAPEX of LTE, and the initial investment is a keypoint in developing countries.

LTE needs lower power consumption than WiMax. One ofthe reasons of this is the use of SC-FDMA modulation in

uplink channels.


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WiMax Architecture vs. LTE Architecture:

Figure (7)

Figure (8)


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Summary:

LTE is well positioned to meet the requirements of next generationmobile networks.

UMTS LTE was designed to simultaneously provide a mix ofservices ranging from real time voice to high-speed Internet browsing.

The use of a single IP type of interconnection simplifiesdeployment, maintenance, and reduces equipment cost.

Base stations (eNBs) can directly connect to each other witheliminates the need for a switching system.

The radio structure is flexible (bandwidth, duplex types) whichallows UMTS LTE to be deployed in different spectrums.

IP Multimedia Subsystem - IMS - is used to setup and managemultimedia sessions with devices in and outside of the UMTS LTE

system.

Multiple types of location based services are integrated intothe UMTS LTE system.

UMTS LTE is a great evolution ofGSM, GPRS, and WCDMA. LTE infrastructure is designed to be as simple as possible. LTE offers scalable bandwidths, from 1.4 MHz up to 20MHz.


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List of figures:

Figure 1 chart representing price per megabyte Vs. different wireless

communication services

Figure 2 LTE architecture

Figure 3 comparison between 3G and LTE networks

Figure 4 comparison between uplink and downlink in LTE ,Wimax ,

HSPA

Figure 5 Evolution of Wimax and LTE

Figure 6 chart representing latency time of LTE Vs. Wimax

Figure 7 Wimax network architecture

Figure 8 simplified LTE architecture


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References:

www.nokiasiemensnetworks.com

www.slideshare.net

CPG0599090904_LTE_Network_Architecture_EN_StraWhitePaper

http://4gwirelessjobs.com/articles/article-detail.php?Analysis-WiMax-&-LTE&Arid=MTA5&Auid=OTU=

www.gsacom.com
http://www.nokiasiemensnetworks.com/http://www.nokiasiemensnetworks.com/http://www.slideshare.net/http://www.slideshare.net/http://4gwirelessjobs.com/articles/article-detail.php?Analysis-WiMax-&-LTE&Arid=MTA5&Auid=OTU=http://4gwirelessjobs.com/articles/article-detail.php?Analysis-WiMax-&-LTE&Arid=MTA5&Auid=OTU=http://4gwirelessjobs.com/articles/article-detail.php?Analysis-WiMax-&-LTE&Arid=MTA5&Auid=OTU=http://4gwirelessjobs.com/articles/article-detail.php?Analysis-WiMax-&-LTE&Arid=MTA5&Auid=OTU=http://4gwirelessjobs.com/articles/article-detail.php?Analysis-WiMax-&-LTE&Arid=MTA5&Auid=OTU=http://www.gsacom.com/http://www.gsacom.com/http://www.gsacom.com/http://4gwirelessjobs.com/articles/article-detail.php?Analysis-WiMax-&-LTE&Arid=MTA5&Auid=OTU=http://4gwirelessjobs.com/articles/article-detail.php?Analysis-WiMax-&-LTE&Arid=MTA5&Auid=OTU=http://www.slideshare.net/http://www.nokiasiemensnetworks.com/

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