lte fundamentals anad rf planning

> This channel is used for paging when the network does not know the location cell of the UE • Broadcast Control Channel BCCH > Provides system information to all mobile terminals connec

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LTE Requirement (3GPP TR 25.913)

• Peak data rate 100 Mbps (DL) and 50 Mbps (UL) to 20 MHz

• Throughput increased by 3-4 times and 2-3 times for the downlink to uplink from HSDPA Rel 6 ( DL = 14.4 Mbps , to use transmitter sites that have been used in UTRA / GERAN

• Throughput increased by 3-4 times and 2-3 time UL = 5.7 Mbps )

• Spectrum efficiency by continuing as for the downlink to uplink from HSDPA

Rel-6 (DL = 14.4 Mbps, UL = 5.7 Mbps)

• Flexible use of spectrum (1.4, 3, 5, 10, 15, 20 MHz)

• Lower latency :

– Radio access network latency ( user plane UE – RNC- UE ) below 10 ms

• The ability of the use mobility up to 350 km / hour

• Coverage up to a radius of approximately 5 km

• Enhance MBMS ( Multimedia Broadcast / Multicast Service ) efficiency ( 1 bit/s/Hz)

• Retaining 3GPP RAT ( Radio Access Technology ) which already exist and support internetworking with him.

• Architecture simplification , minimization and packet – based interface , full IP

LTE Architecture

In the LTE network is divided into

2 basic network, namely:

1 E UTRAN (Evolved Universal Terrestrial Radio Access Network)

2 EPC (Evolved Packet Core)

 The IP Multimedia Sub-System (IMS) is a good example of servicemachinery that can be used in the Services Connectivity Layer toprovide services on top of the IP connectivity provided by the lowerlayers

 For example, to support the voice service, IMS can provide Voice over

IP (VoIP) and interconnectivity to legacy circuit switched networksPSTN and ISDN through Media Gateways it controls

• Functionally the EPC is equivalent to the packet switched domain of the

existing 3GPP networks

• EPC consist of :

– MME ( Mobility Management Entity )

– SAE GW represents the combination of the two gateways, Serving

Gateway (S-GW) and Packet Data Network Gateway (P-GW)

– Home Subscriber Server (HSS)

– Policy and Charging Rules Function (PCRF)

( Evolved Universal Terrestrial Radio Access Network)

 Mobility Management Entity (MME)

– MME is a controller at each node on the LTE access network At UE

in idle state (idle mode), MME is responsible for tracking andpaging procedure which includes retransmission therein

– MME is responsible for selecting SGW (Serving SAE Gateway)which will be used during initial attach EU and the EU time to dointra - LTE handover

– Used for bearer control, a different view R99 / 4 which is stillcontrolled by the gateway

 Policy and Charging Rules Function (PCRF)

In order to handle QoS as well as control rating and charging, and

billing

EPC Con’t

 Home Subscriber Server (HSS)

For management and security subscriber, combination AUC and HLR

 Serving SAE Gateway (SGW)

- Set the path and forwards the data in the form of packets of each user

- As an anchor / liaison between the UE and the eNB at the time of the inter handover

- As a liaison link between the 3GPP LTE technology with the technology(in this case the 2G and 3G)

 Gateway Packet Data Network (PDN GW)

- Provides for the UE 's relationship to the network packet

- Provide a link relationship between LTE technology with technology non 3GPP (WiMAX) and 3GPP2 (CDMA 20001X and EVDO)

EPC Con’t

 Role of Radio Access Network (RAN), namely Node B and RNC isreplaced with ENB, so as to reduce operational and maintenance cost

of the device other than the simpler network architecture

 E-nodeB functions : all radio protocols, mobility management, header

compression and all packet retransmissions

 As a network, E-UTRAN is simply a mesh of eNodeBs connected to

neighboring eNodeBs with the X2 interface.

(Evolved Universal Terrestrial Radio Access Network)

FREQUENCY & BANDWIDTH IN LTE

Key Consideration to Spectrum Selection

* Band Selection Source: 3GPP TS 36.101

Illustration for Spectrum Selection

Channel Bandwidth Flexibility

 LTE provides channel bandwidth flexibility for operation in differently-sized

 LTE supports paired and unpaired spectrum on the same hardware spectrum

Channel Bandwidth Impact

OFDM

OFDM vs Single Carrier

Spectral efficiency of OFDM compared to classical multicarrier modulation: (a) classical multicarrier system spectrum; (b) OFDM system spectrum.

Motivation for OFDM Approaches

OFDM Concept

• Multicarrier modulation/multiplexing technique

• Available bandwidth is divided into several sub-channels

• Data is serial-to-parallel converted

• Symbols are transmitted on different sub-channels

OFDM Block Diagram (Tx)

Diagram Block Contents:

• S/P  Serial to Parallel Converter

• Sub-Carrier Modulator

• IFFT  Inverse Fast Fourier Transform

• P/S  Parallel to Serial Converter

• DAC  Digital to Analog Converter

OFDM Block Diagram (Rx)

Diagram Block Contents:

• S/P  Serial to Parallel Converter

• Sub-Carrier Modulator

• IFFT  Inverse Fast Fourier Transform

• P/S  Parallel to Serial Converter

• DAC  Digital to Analog Converter

Cyclic Prefix

• Useful for multipath delay spread

• Guard Interval (cyclic prefix) : short & long

Type of Cyclic Prefix

OFDMA & SC-FDMA

OFDMA vs SCFDMA

 Definition

 OFDMA is a multiple access technique based on OFDM as the

modulation technique It is used for DL transmission in LTE

 SC-FDMA is a hybrid UL transmission scheme in LTE which has carrier transmission systems with the long symbol time and flexible frequency allocation of OFDM

single-SC-FDMA Diagram Block

SC-FDMA frequency-domain transmit processing (DFT-S-OFDM) showing localized and distributed subcarrier mappings.

Type of OFDMA Sub-Carrier

Nsubcarrier data  See slide #19 or 3GPP TS 36.104

Npilot  NFFT-Point - Nsubcarrier data

MULTI ANTENNA TECHNIQUE

Multiple Antenna Technique

Multiple Antenna Technique

 Two popular techniques in MIMO wireless systems:

Spatial Diversity: Increased SNR

• Receive and transmit diversity

mitigates fading and improves

link quality

Spatial Multiplexing: Increased rate

• Spatial multiplexing yields

substantial increase spectral efficiency

Spatial Diversity

Transmit Diversity

• Space-time Code (STC): Redundant data sent over time and space domains (antennas).

• Receive SNR increase about linearity with diversity order NrNt

• Provide diversity gain to combat fading

• Optional in 802.16d (2x2 Alamouti STBC), used in 3G CDMA

Spatial Multiplexing

MIMO Multiplexing

• Data is not redundant – less diversity but less repetition

• Provides multiplexing gain to increase data-rate

• Low (No) diversity compared with STC

LTE SUPPORTING TECHNOLOGIES

 HARQ

 AMC

HARQ or retransmission

scheme in LTE use wait retransmission system.

stop-and-Adaptive Modulation

SNR-CQI Mapping for BLER 10%

Adaptive Modulation Illustration

Constellation Diagram

QPSK

16 QAM

64 QAM

Adaptive Modulation and Coding

Standard for CQI mapping

Scheduling

Control Plane

Control Plane (C-Plane) is use to describe

the protocols that convey information from the DTE to the end user (the control) of a node, or between nodes in the network

to conveying required information to set,

control and clearing the connection protocol

User plane (U-plane) is a protocol used directly in the transfer of user data from the DTE (Data Terminal Equipment) to the other end-users U- plane provides the function of delivery or transfer user

information, and include all relevant mechanisms of information

transfer such as flow control and error recovery In the user plane used approach layer

User Plane

CONTROL PLANE

USER PLANE

LTE CHANNELS

LTE Layer Mapping

Layer Function

• Radio Link Control Layer (RLC)

> Retransmission

> Segmentation

• Medium Access Control Layer (MAC)

> Uplink and downlink scheduling at the eNodeB

> HARQ

• Physical Layer (PHY)

> Modulation/demodulation

> Coding/decoding

LTE Downlink Channel Mapping

LTE Downlink Logical Channels

• Paging Control Channel ( PCCH)

> A downlink channel that transfers paging information and system

information change notifications

> This channel is used for paging when the network does not know

the location cell of the UE

• Broadcast Control Channel (BCCH)

> Provides system information to all mobile terminals connected to

the eNodeB

> A downlink channel for broadcasting system control information

• Common Control Channel (CCCH)

> Channel for transmitting control information between UEs and

network

> This channel is used for UEs having no RRC connection with the

network

• Multicast Control Channel (MCCH)

> A point-to-multipoint downlink channel used for transmitting MBMS

> Control information from the network to the UE, for one or several

MTCHs

> This channel is only used by UEs that receive MBMS

• Dedicated Control Channel (DCCH)

> A point-to-point bi-directional channel that transmits dedicated

control information between a UE and the network

> Used by UEs having an RRC connection

> This control channel is used for carrying user-specific control

information, e.g for controlling actions including power control,handover, etc

LTE Downlink Logical Channel Con’t

LTE Downlink Logical Channel Con’t

• Multicast Traffic Channel (MTCH)

> A point-to-multipoint downlink channel for transmitting traffic data

from the network to the UE

> This channel is only used by UEs that receive MBMS

• Dedicated Traffic Channel (DTCH )

> A point-to-point channel, dedicated to one UE, for the transfer of

user information

> A DTCH can exist in both uplink and downlink

LTE Downlink Transport Channel

• Paging Channel ( PCH)

> Supports UE discontinuous reception (DRX) to enable UE power

saving

> Broadcasts in the entire coverage area of the cell;

> Mapped to physical resources which can be used dynamically also

for traffic/other control channels

• Broadcast Channel ( BCH )

> The LTE transport channel maps to Broadcast Control Channel

(BCCH)

> Fixed, pre-defined transport format

> Broadcast in the entire coverage area of the cell

• Multicast Channel ( MCH)

> Broadcasts in the entire coverage area of the cell;

> Supports MBSFN combining of MBMS transmission on multiple cells;

> Supports semi-static resource allocation e.g with a time frame of a long

cyclic prefix

• Downlink Shared Channel ( DL-SCH )

> Main channel for downlink data transfer It is used by many

logical channels

> Supports Hybrid ARQ

> Supports dynamic link adaptation by varying the modulation, coding and

transmit power

> Optionally supports broadcast in the entire cell;

> Optionally supports beam forming

> Supports both dynamic and semi-static resource allocation

> Supports UE discontinuous reception (DRX) to enable UE power saving

> Supports MBMS transmission

LTE Downlink Transport Channel Con’t

LTE Downlink Physical Channel

• Physical Downlink Shared Channel ( PDSCH)

> This channel is used for unicast and paging functions

> Carries the DL-SCH and PCH

> QPSK, 16-QAM, and 64-QAM Modulation

• Physical Downlink Control Channel ( PCSCH)

> Informs the UE about the resource allocation of PCH and DL-SCH,

and Hybrid ARQ information related to DL-SCH

> Carries the uplink scheduling grant

> QPSK Modulation

Uplink Physical Channels

• Physical HARQ Indicator Channel (PHICH)

> Used to report the Hybrid ARQ status

> Carries Hybrid ARQ ACK/NAKs in response to uplink transmissions

> QPSK Modulation

• Physical Braodcast Channel (PBCH)

> This physical channel carries system information for UEs

requiring to access the network

> QPSK Modulation

LTE Uplink Channels

Uplink Physical Channels

• Physical Radio Access Channel ( PRACH)

> for random access functions

• Physical Uplink Shared Channel ( PUSCH)

> Carries the UL-SCH

> QPSK, 16-QAM, and 64-QAM Modulation

• Packet Uplink Control Channel ( PUCCH)

> Sends Hybrid ARQ ACK/NAKs

> Carries Scheduling Request (SR)

> Carries CQI reports

> BPSK and QPSK Modulation

Uplink Transport Channels

• Random Access Channel (RACH)

> Channel carries minimal information

> Transmissions on the channel may be loss due to collisons

• Uplink Shared Channel ( UL–SCH )

> Optional support for beam forming

> Support HARQ

Uplink Logical Channels

• Common Control Channel ( CCCH)

> Channel for transmitting control information between Ue and

network

> This channel is used for UEs having no RRC connection with the

network

• Dedicated Control Channel ( DCCH)

> A point-to-point bi-directional channel that transmits dedicated control

information between a UE and the network

> Used by UEs having an RRC connection

• Dedicated Traffic Channel ( DTCH)

> A point-to-point channel, dedicated to one UE, for the transfer of user

information

> A DTCH can exist in both uplink and downlink

LTE FRAME STRUCTUR

> Functions

System can maintain synchronization and manage the different type of information that need to be carried between the eNodeB and UE

> LTE frame structure consist of

1 FDD ( Frequency division duplex)

2 TDD ( Time division duplex )

> A radio frame has duration of 10 ms

> A resource block spans 12 subcarriers over a slot duration of 0.5 ms

> BW RB = 180 KHz

> BW Subcarrier = 15 kHz

FDD Frame structure

LTE TDD Sub Frame Allocations

D : sub frame for downlink transmission

S :"special" sub frame used for a guard time

U : sub frame for uplink transmission

Planning Coverage

Downlink Link Budget LTE

Unit Value Info

j Control Channel Overhead dB 1 j

MAPL Calculation

R T

c

p 46,3 33,9 (logf ) 13,82 logh a(h ) (44,9 6,55logh )logd C

(d/100) log

47.9 109.78

Lp  

d log hB]

log 6,55 – [44,9 CH

hB log 13,82 –

-f log 26,16 69,55

Pathloss SUI

Lp = 109.78 + 47.9 log (d/100)

78 109 )

100 /

) 78 109 (

) 100 /

9 47 / ) 78 109 (

10 )

100 /

d

9 47 / ) 78 109 (

157 (

1000



Radius Calculation

L = 2,6 d 2

L = 1,95 2,6 d 2

L = 1,3 2,6 d 2

x 1.95

PLANNING CAPACITY

Calculation steps:

1 Number of user

2 User density

3 Services and Type

4 Penetration : building, vehicular, pedestrian

5 BHCA and call duration

6 OBQ

7 Site calculation

Number of User

Where:

• Un : num of user on year ‘n’

• Uo : initial num of user (based on urban/sub-urban)

• a : percent of cellular user (%)

• b : penetration of operator A (%)

• d : Percent of LTE user

• N : num of civilian in the object area

• gf : num of user growth factor

• n : planned year

• u/sub : urban or sub-urban penetration (%)

Uo u = u x Uo N

Un = Uo (1 + gf) n

Uo N = a x b x d x N

Customer Prediction Parameter

Ex :

• Population = 1445892 people

• Cellular penetration = assumption 80%

• LTE penetration = assumption 10 %

• LTE provider A penetration = assumption 50 %

User prediction in 5th years

• U5 = 57835 ( 1 + 0.05 )5 assumption fp=5%

= 73814 user

Population 1445892 people

Customer cellular (80%) 1156713 user

Customer LTE (10%) 115671 user

Customer LTE provider A (50%) 57835 user

Example User Calculation

Ex :

User Density

• Lsub : sub-urban area wide

• Cu : Urban area density

• Csub : sub-urban area density

L u = L x u L sub = L x sub

C u = Un/ L u C sub = Un/L sub

Example User Density Calculation

Ex :

• urban area penetration = assumption 40 %

• suburban area penetration = assumption 40 %

=>

Urban area wide (Lu) : 242,928 km2

Sub-urban area wide (Lsub) : 242,928 km2

=>

Cu = 44288 / 242,928 = 182,31232 user/km2

Csub = 29525 / 242,928 = 121,54155 user/km2