LTE Basics

From LTE basics to 9155 LTE RF Design

2 | Presentation Title | Month 2008

LTE Basics

OFDM Fundamentals



Basic of OFDM


Basic of OFDMWaveform


Basic of OFDMSending modulation symbol in parallel


Basic of OFDMSymbol extract


Basic of OFDM


Basic of OFDMOrthogonality lost


Basic of OFDMDoppler & frequency offset effects


Basic of OFDMMulti-path effect


Basic of OFDMMulti-path effect


Basic of OFDMCP length


Basic of OFDMOFDM scalable


Basic of OFDMFull Tx/Rx chain


LTE Basics

DOWNLINK STRUCTURE


DL Physical Channels


DL Channels Mapping


LTE Downlink: Frame Format, Channel Structure & Terminology


LTE Downlink: Number of Resource Blocks & Numerology


Downlink common Reference Signal structure

Reference signal symbol distribution sequence over 12 subcarriers x 14 OFDM symbols.

The Reference signal sequence is correlated to Cell ID.


Downlink common Reference Signal structure per number of antenna port


PBCH, SCH Time and frequency location


Basic of cell search


Primary BCH & Dynamic BCH


Primary BCH & Dynamic BCH


PCFICH & PHICH


PDCCH


PDCCH: DCI formats carried

DCI includes resource assignments and other control information


Downlink Shared Channel (DL-SCH)


DL Power settings

PDCCH PBCH

Based o the simus done by R&D and also on first trials results the DL power settings is detailed in the slides below


DL Power settings

LA 0.x


DL Power settings

LA 1.0 RRH 30W


DL Power settings

LA 1.0 RRH 40W


LTE Basics

UPLINK STRUCTURE


UL Physical Channels


UL Channels Mapping


SC-FDMA principle


SC-FDMA principle


SC-FDMA Tx/Rx chain


LTE Uplink: Number of Resource Blocks & Numerology


Demodulation Reference Signal & Sounding Reference Signal


Demodulation Reference Signal & Sounding Reference Signal


PUCCH


PUCCH


PUCCH


PRACH


Radom Access procedures


LTE Basics

UL Power Control


IoT Control Mechanism (Inter-cell Power Control)

Setting of Target_SINR_dB determines the IoT operating point

Especially in a reuse-1 deployment, it is critical to manage the uplink interference level

In LTE, e-NBs can send uplink overload indications to neighbor e-NBs via the X2 interface

Power control parameters (i.e. Target SINR) can be adapted based on overload indicators Allows control of the IoT level to ensure coverage and system stability

PC params PC paramsMeasure

Interference, emit overload indicator

Based on overload indicator from neighbor cell,

adapt PC paramsinterference

Overload indicator (X-2 interface)


Fractional Power Control

While using the same target SINR for each user results in very good fairness (as far as power allocation is concerned), it also results in poor spectral efficiency

An improved power control scheme called Fractional Power Control adjusts the target SINR in relation to the UE’s path loss to its serving sector

UE_TxPSD_dBm = x PL_dB + Nominal_Target_SINR_dB + UL_Interference_dBm

is called the fractional compensation factor, and is sent via cell broadcast; 0 < < 1

Target SINR

Target_SINR_dB = Nominal_Target_SINR_dB - (1-) x PL_dB

Target SINR increases with decreasing path loss

Flexible trade-off between cell edge rate and average spectral efficiency


Improved Power Control Based on Neighbor Cell Path Loss

Path loss to the serving cell is not indicative of the amount of interference a user will generate to neighboring sectors

An improved power control scheme adjusts the target SINR in relation to PL_dB = PL_strongestNeighborCell_dB –PL_servingCell_dB

UE_TxPSD_dBm = PL_dB + Nominal_Target_SINR_dB + (1-) x PL_dB + UL_Interference_dBm

(1-) x PL_dB is sent to each UE via higher layer (RRC) signaling

Target SINRTarget_SINR_dB = Nominal_Target_SINR_dB

+ (1-) x PL_dB

Target SINR increases with increasing “radio position”


LTE Basics

Scheduler


Scheduler


UL Scheduling mechanism


DL Scheduling mechanism


Channel Quality Indicator, Pre-coding Matrix Indicator, Rank Indicator


Scheduler weighted proportional fair


Scheduler proportional fair principles








Frequency Non-Selective Scheme

The SRS SYNC SINR is a scalar quantity per user that is formed by averaging the SRS SINR across PRBs and then filtered in time; used to form a single priority metric, which is replicated and used for all PRBs

To support a large number of UEs, the SRS period needs to be reduced given the multiplexing capabilities

(max of 8 UEs per SRS transmission per frequency comb)

The regular MPE algorithm as in the FSS algorithm is then utilized, which minimizes testing/verification to just the new code introduced

Currently also investigating an intermediate solution where the resolution of the frequency selective scheduler is reduced by a certain factor in order to retain some frequency selectivenessin the scheduling while reducing complexity (study in progress)

Single priority metric formed and used in the first stage of the MPE algorithm

Then MPE algorithm continues as in FSS scheme

12

34

56

78

9

UE 1

UE 2

UE 3 0

1

2

3

4

5

6

Priority Metric

Resource Unit Index

UE 1UE 2UE 3


Frequency Re-use strategies

Frequency re-use1 Fractional Frequency re-use


Frequency Re-use strategies

Soft Frequency re-use or dynamic frequency re-use


LTE Basics

Link adaptation


DL MCS table


UL MCS table


LTE Basics

Multi Antenna Technology Roadmap


MIMO Configuration


Antennas Configuration


Antennas Configuration


Spatial Multiplexing


LA1.0 Scheme supported


Scheme supported after LA1.0

LTE Link BudgetsUplink Link Budget Considerations


Uplink Link BudgetMain Principles

Link Budget is performed for one mobile located at cell edge (for each service) transmitting at max power

The IoT (Interference over Thermal Noise) experienced by this user on the UL depends on the frequency reuse scheme and the service data rate and corresponding SINR that is guaranteed for cell edge users

cell radius

MAPL

Required Received Signal

Max UE transmit PowerUPLINK Analysis is an MAPL analysis


Uplink Link BudgetMain Principles

Receiver Sensitivity

Transmit Power

Losses andMargins Gains Interference

Feeder losses

Penetration Loss (outdoor/indoor)

Shadowing Margin

Handoff Gain

Body Loss

eNode-B Antenna Gain

UE Antenna Gain

Derived from SINR

performances

Interference Margin

= MAPL

UE Transmitpower

(23dBm)

Uplink Path

Maximum Allowable Path Loss

UL link budget elaborated for user of service k at cell edge transmitting at maximum power


Uplink Link BudgetRationale Behind LKB Formulation

Link budgets are formulated for one service that is to be guaranteed at cell edge (RangeUL_Guar_Serv)

For more limiting service rates link budgets are formulated under the assumption they are not guaranteed at cell edge but at a reduced coverage footprint

RangeUL_Guar_Serv

128kbps

256kbps

512kbps

UL Rates


Uplink Link BudgetExample for one service

Dense Urban (2.6GHz) PS 128

Required Data Rate 128 kbpsNo. Resource Blocks Required 3 RB

MCS MCS 8Used Bandwidth 540 kHz

Target C/I -3.0 dBeNode-B Noise Figure 2.5 dB

eNode-B Sensitivity -117.2 dBmAntenna Gain 18.0 dBi

Cable & Connector Losses 0.5 dBBody Losses 0 dB

Additional UL Losses 0 dBCell area coverage probability 95%

Overall standard deviation 8.0 dBShadowing Margin 8.6 dB

Handoff Gain 3.6 dBFast Fading Margin 0 dBPenetration Margin 21 dB

Fixed IoT 3.0 dBUE Antenna Gain 0 dBi

UE Max Transmit Power 23.0 dBmMAPL 128.7 dB

UL Cell Range 0.46 km

No. Resource Blocks to Reach Data Rate

Signal to Interference Ratio per Resource Block

Noise Figure of the eNode-B is supplier dependent

Based on SINR, Noise Figure, Thermal Noise, Bandwidth Used

Optimal Modulation & Coding Scheme (MCS)


Uplink Link BudgetReceiver Sensitivity

eNode-B Receiver Sensitivity

Minimum required signal level to reach a given quality (SINR target) when facing only thermal noise

Where:

F: eNode-B Noise figure in dB

Nth: Thermal noise density, 10log(Nth) =-174 dBm/Hz

SINRdB: Signal to Interference ratio per Resource Block

NRB: Number of resource blocks (RB) required to reach a given data rate

WRB: Bandwidth of one Resource Block

– One Resource Block is composed of 12 subcarriers, each of a 15kHz

bandwidth – so WRB = 180kHz.\

SensitivitydBm = SINRdB + 10.log10(F.Nth.NRB.WRB)

Service dependent


Uplink Link BudgetSINR Performances - Overview

SINR Target depends on:

eNode-B equipment performance

Radio conditions (multipath fading profile, mobile speed)

Receive diversity (2-way by default or optional 4-way)

Targeted data rate and quality of service

The Modulation and Coding Scheme (MCS)

Max allowed number of HARQ transmissions (Maximum of 4 on UL)

HARQ Operating Point – 1% Post HARQ BLER target considered by default

Derived from link level simulations or better by equipment measurements (lab or on-field measurements)


Uplink Link BudgetSINR Performances - Channel Model

In reality, a mix of multipath conditions exist across a typical cell

For coverage assessment, the worst case model should be considered

ITU VehA multipath channel model are considered a good compromise

For LTE some evolved multipath channel models have been defined such as EVA5Hz or EPA5Hz

These are an extension of the VehA and PedA models used in UMTS to make them more suitable for the wider bandwidths encountered with LTE, e.g. >5MHz

Main difference lies in the definition of a Doppler frequency instead of a speed, making the model useable for different frequency bands

All SINR performances used in the link budget are for all EVehA3 and EVehA50 channel models


Uplink Link BudgetSINR Performances - Link Level Results for 10MHz Bandwidth (50 RB)

LTE UL Throughput v.s. SNR, max 4HARQ Tx, EPedB-3km

0

5000

10000

15000

20000

25000

30000

35000

40000

-10 -5 0 5 10 15 20 25 30

SINR (dB)

Thro

ughp

ut (

kbps

)

MCS = 0 MCS = 1MCS = 2 MCS = 3MCS = 4 MCS = 5MCS = 6 MCS = 7MCS = 8 MCS = 9MCS = 10 MCS = 11MCS = 12 MCS = 13MCS = 14 MCS = 15MCS = 16 MCS = 17MCS = 18 MCS = 19MCS = 20 MCS = 21MCS = 22 MCS = 23MCS = 24 MCS = 25MCS = 26 MCS = 27MCS = 28 T'put (kbps)


Uplink Link BudgetSINR Performances - Selection of Optimal SINR Figures

There are a number of possible solutions that can be used to provide a given throughput – solutions comprise a combination of:

Modulation & Coding Scheme (MCS)

Number of Resource Blocks (RB)

Optimization Objective:

Select # RB’s and MCS so as to maximize the receiver sensitivity and thus the link budget

While at the same time respecting the selected HARQ operating point (1% post HARQ BLER objective)


Uplink Link BudgetSINR Performances - Summary for UL 10MHz Bandwidth (1x2 RxDiv)

Performance figures for typical UL link budget rates

Number of RB’s

SINR (include margins)

MCS, TBS and # HARQ Transmissions

Service VoIP PS 64 PS 128 PS 256 PS 384 PS 512 PS 768 PS 1000 PS 2000

Bit Rate 12.2 64 128 256 384 512 768 1000 2000

MCS 6 6 8 10 10 10 10 10 10

TBS 328 176 392 872 1384 1736 2792 3496 6968

Modulation QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK

Post HARQ BLER 1% 1% 1% 1% 1% 1% 1% 1% 1%

Required # of RB 1 2 3 5 8 10 16 20 40

SINR (EVehA 3km/h) -3.7 dB -3.6 dB -3.0 dB -2.4 dB -2.9 dB -3.1 dB -3.4 dB -2.9 dB -3.3 dB

Rx Sensitivity -123 dBm -120 dBm -117 dBm -114 dBm -113 dBm -112 dBm -110 dBm -109 dBm -106 dBm


Uplink Link BudgetSINR Peformances - MCS and TBS Tables

Some Background Info

Modulation & Coding Scheme (MCS)

This determines the Modulation Order which in turn determines the TBS Index

Number of Resource Blocks

For a given MCS the Transport Block Size (TBS) is given different numbers of resource blocks

MCS Index, IMCS

Modulation Order, QM

TBS Index, ITBS

0 QPSK 01 QPSK 12 QPSK 23 QPSK 3… QPSK 4

NPRB

ITBS 1 2 3 4 …0 16 32 56 88 1201 24 56 88 144 1762 32 72 144 176 2083 40 104 176 208 2564 56 120 208 256 3285 72 144 224 328 4246 328 176 256 392 504… 104 224 328 472 584

MCS Table TBS Table


Uplink Link BudgetImplementation Margins

SINR performances from link level simulations assume ideal scheduling and link adaptation – reality will not be as good …

For example in the downlink, we consider: Error free CQI feedback, Perfect PDCCH-PCFICH decoding, CQI feedback rate 1/20ms, etc.

To account for such ideal assumptions there are currently two key elements to the margins incorporated into in SINR performances used in UL budgets today:

Implementation margin to account for the assumptions implicit in the link level simulations used to derive the SINR performances

Currently considered to be ~1dB

No variability is assumed for different environments or UE mobility conditions

Will be tuned based on SINR measurements (not yet performed)

ACK/NACK margin to account for the puncturing of ACK/NACK onto the PUSCH

A 1dB margin is applied for VoIP services and 0.5dB for higher data throughputs


Uplink Link BudgetConsideration of Explicit Diversity Gains

The SINR performance figures considered by Alcatel-Lucent in UL and DL link budgets are based on link level simulations that already account for the corresponding transmit and receive diversity gains, i.e.

UL: default 1x2 Rx Diversity

2RxDiv gain accounted for in the SINR figures

To account for 4RxDiv on the UL an additional 2-3dB gain is considered on the 2RxDiv SINR figures

DL: default 2x2 Tx Diversity

SFBC pre-coding gains + 2RxDiv gain at the UE are accounted for in the SINR figures

Note that an additional power combining gain is considered at the transmit side, i.e. for a 2 x 40W TxDiv configuration a 80W transmit power is applied in DL link budgets


INTERNAL NOTE – Noise Figure

The Noise Figure of the eNode-B is supplier dependent

Typically the Noise Figures of e-NodeBs range between 2 to 3dB

RRH Type Typical Noise FigureRRH2x (lower 700) 2.2dB

900 TBD - 2.5dB (assumed)MC-TRX (1800) 3 dBMC-RRH (1800) 2.5 dB

AWS TBD – 2.5dB (assumed)RRH2x (2600) 2.6 dBTRDU (2600) 2.6 dB

Typical RRH Noise Figures for ALU product (June 2009)


Uplink Link BudgetExercise

Compute eNode-B sensitivity in VehA 3km/h

for VoIP 12.2kbps @ 1% Post-HARQ BLER

For PS 384kbps @ 1% Post-HARQ BLER

Alcatel-Lucent equipment:

Typical eNode-B Noise Figure: 2.5dB

SINR figures: -3.7 dB for VoIP 12.2, -3.3dB for PS384

ANSWER: Sensitivity: -122.6 dBm for speech, -113.2 dBm for PS384















Depends on UE Power Class

0dBi by default

3dB body loss when speech usage (UE near head), 0dB body loss when data usage

Typical gain of Tri-sectored antenna, depends on frequency band

Depends on feeder type, length and frequency band


Uplink Link BudgetUE Characteristics

LTE UE Max Transmit Power

Depends on the power class of the UE

Only one power class is defined in 3GPP TS 36.101: 23dBm output power is considered with a 0 dBi antenna gain; ± 2dB tolerance in the standard

WCDMA UE Max Transmit Power

Multiple power classes were defined in 3GPP TS 25.101, the most prevalent WCDMA UE’s today are considered to be class 3 (24dBm +1/-3dB)

The corresponding tolerance ranges for both WCDMA and LTE terminals are in fact the same:

4dB range 21-25dBm

While the nominal Tx powers differ by 1dB

Currently consider 23dBm in UL LTE link budgets















Depends on depth of coverage (e.g. deep indoor, indoor daylight, outdoor). Also

accounts for the indoor shadowing margin

Shadowing margin due to shadowing standard deviation

Handoff gain


Uplink Link BudgetShadowing Margin

Shadowing Margin:

Slow fading signal level variations due to obstacles

Modelled (in dB) as a Gaussian variable with zero-mean and standard deviation depending on the environment, typically 6 to 8dB

The shadowing standard deviation can include the variability associated with the indoor penetration. However, it is recommended to consider this as part of the penetration margin

Impact on link budget :

Take a margin to ensure the received signal is well received (above required sensitivity) with a given probability

Typically 95% in Dense Urban, Urban and Suburban and 90% in Rural

Computation as for UMTS and CDMA.


Uplink Link BudgetHandoff Gain

Unlike UMTS/WCDMA or CDMA, there is no soft-handoff functionality for LTE

No soft-handoff gain considered for LTE

Far too pessimistic to only consider the shadowing margin computed with one cell unless considering an isolated cell

A mobile at the cell edge can still handover to a neighbor cell with more favorable shadowing, i.e. a lower path loss consider a Handoff Gain (or best server selection gain)

Reference article: Analysis of fade margins for soft and hard handoffs, Rege, K.M.; Nanda, S.; Weaver, C.F.; Peng, W.-C., PIMRC 95

INTERNAL NOTE: This hard handoff gain can be considered for any system without soft handoff. So

this is the case for GSM. However no gain is typically applied in GSM. For LTE the sampling

frequency for handoff decisions as well as the handoff speed itself is much faster than GSM this

leads to an LTE handoff gain not much less than that considered for WCDMA.


Shadowing Standard Deviation 6 dB 6 dB 7 dB 7 dB 8 dB 8 dB 10 dB 10 dB

Cell Area Coverage Probability 90% 95% 90% 95% 90% 95% 90% 95%

Cell Edge Coverage Probability 71% 84% 73% 85% 75% 86% 78% 88%

Handoff Hysteresis 2 dB 2 dB 2 dB 2 dB 2 dB 2 dB 2 dB 2 dB

Shadowing Margin (no SHO gain) 3.3 dB 5.9 dB 4.3 dB 7.2 dB 5.4 dB 8.7 dB 7.7 dB 11.7 dB

SHO Gain 2.7 dB 2.8 dB 3.1 dB 3.4 dB 3.6 dB 3.9 dB 4.7 dB 5.0 dB

3 km/h - HHO Gain 2.3 dB 2.5 dB 2.8 dB 3.1 dB 3.4 dB 3.6 dB 4.4 dB 4.8 dB



Uplink Link BudgetHandoff Gain - Example

Antenna Height 30 m

K2 Propagation Model 35.2

Shadowing Correlation 0.5

Hysteresis 2 dB

HO sampling time 20 msec

# of samples to decide HO 4 samples

Correlation distance 50 m

Cell Range 100%

Reference article: Analysis of fade margins for soft and hard handoffs, Rege, K.M.; Nanda, S.; Weaver, C.F.; Peng, W.-C., PIMRC 95

Typical for Dense Urban, Urban and Suburban Indoor

Typical for Suburban Incar & Rural


Uplink Link BudgetHandoff Gain - Example

Note that the full Handoff Gain is only applicable for UE’s located at the cell edge where we consider one rate guaranteed at the cell edge and others guaranteed within that coverage footprint, the other services will not take benefit of the full handoff gain

Dense Urban, Sigma = 8dB, 95% coverage reliability, 3km/h mobility

128kbps 256kbps 512kbps

UL Rates0.0 dB

0.5 dB

1.0 dB

1.5 dB

2.0 dB

2.5 dB

3.0 dB

3.5 dB

4.0 dB

0% 20% 40% 60% 80% 100%

% of Cell Range

Han

doff

Gai

n


Uplink Link BudgetPenetration Margin

The penetration losses characterize the level of indoor coverage targeted by the operator (deep indoor, indoor daylight, window, incar, outdoor, etc)

Highly dependent on the wall materials and number of walls/windows to be penetrated

It is recommended to consider the penetration margin as a single “worst case” margin as the shadowing standard deviation doesn’t include the indoor penetration variability

Typical Penetration Losses at 2GHz

Environment Penetration Margin (dB)

Dense Urban – Deep Indoor 20

Urban - Indoor 17

Suburban - Indoor 14

Rural – Incar 8


INTERNAL NOTE – Penetration Losses

For 700/850/900MHz, lower penetration losses can be considered

Note that the frequency dependency of the penetration losses is very material-dependent

Typically, we can assume 2dB lower penetration margins compared to those at 2GHz

For 2.6GHz, higher penetration losses could be considered

Note that the frequency dependency of the penetration losses is very material-dependent

Typically, we can assume 2dB higher penetration margins compared to those at 2GHz















Interference Margin or IoT

This sensitivity is calculated for noise only. A margin must be considered for the

interference above noise: Interference Margin


Uplink Link BudgetInterference Margin

Sensitivity figures typical consider only thermal noise, the real interference, Ij, must also be considered (not only the thermal noise)

Interference margin or IoT (Interference over Thermal Noise)

A reuse of 1 is typical (option to use schemes such as soft fractional reuse or interference coordination)

The IoT operating point can be set to achieve a minimum data rate at cell edge and/or to match incumbent technology coverage

dBdBmj ceMarginInterferenySensitivitC Power, ReceiveddBm

WN

I10logceMarginInterferen

th

jdB


Uplink Link BudgetWCDMA Noise Rise - What’s Different Between LTE and WCDMA?

By definition, Cell Load and Total Interference rise (“Noise Rise”) are linked:

where Itotal is the total received power at the node B (including the useful signal)

Differences with LTE

Interference from adjacent cells onlyfor LTE (no intracell interference)

Max WCDMA cell load is dependenton power control stability

No concept of cell load for LTE

ULo

totaldBtot x

WNIi

11010 log log_

0

5

10

15

20

25

30

0 10 20 30 40 50 60 70 80 90 100

Cell Load (%)

Noi

se R

ise

(dB

)

50% cell load3dB Noise Rise


LTE IoTWhat Determines the IoT for LTE?

The average IoT is dependent upon the targeted cell edge data rate (SINR)

The higher the cell edge SINR target, the higher the average IoT

Ultimately there is a point at which the increased IoT can not be sustained with the corresponding SINR

Based on system level simulations:

0

1

2

3

4

5

6

7

8

9

-7 -6 -5 -4 -3 -2 -1 0 1 2

Cell Edge SINR Target, TSINR (dB)

Ave

rage

IoT

(dB)

0

100

200

300

400

0 1 2 3 4 5 6 7 8 9

Mean IoT (dB)

Avg

and

5%

UE

Thro

ughp

ut (

kbps

)

Average Throughput

Cell Edge Throughput


LTE IoTWhat Determines the IoT for LTE?

For LTE the IoT can be expressed as:

IoT = 1 / (1 - RBLoad x FAvg x TSINR)

Where

RBLoad = Average % loading of the resource blocks of adjacent cells

Under full loading this can be considered to be 100%

FAvg = The average ratio between extracell interference and useful signal received at the eNode-B

Based on system level simulations the typical value of FAvg for UL fractional power control is ~0.8 – this is quite comparable to that used for WCDMA

TSINR = SINR target at the cell edge


LTE IoTThe IoT for Targeted LTE Cell Edge Rates?

VoIP AMR 12.2 with

TTI Bundling

PS 8 PS 64 PS 128 PS256 PS 384 PS 500 PS 1Mbps PS 2Mbps

12.2 8 64 128 256 384 500 1000 2000Modulation QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK

Coding Rate 0.31 0.14 0.35 0.48 0.62 0.61 0.61 0.62 0.61Max # HARQ Tx 4 4 4 4 4 4 4 4 4Post-HARQ BLER 1% 1% 1% 1% 1% 1% 1% 1% 1%Required # of RB 1 1 2 3 5 8 10 21 41

VehA 3km/h -3.7 -3.38 -3.4 -2.9 -2.7 -3.3 -3 -3.3 -3.4VehA 50km/h -2.1 -3.8 -2.8 -2.6 -2.1 -2.5 -2.5 -2.7 -2.9

RBLoad 100%

FAvg 0.8 IoT = 1 / (1-RBLoad.FAvg.TSINR)

VehA 3km/h 1.8 dB 2.0 dB 2.0 dB 2.3 dB 2.4 dB 2.0 dB 2.2 dB 2.0 dB 2.0 dBVehA 50km/h 3.0 dB 1.8 dB 2.4 dB 2.5 dB 3.0 dB 2.6 dB 2.6 dB 2.4 dB 2.3 dB

10 MHz bandwidth - 2RxDiv - Product Release LAx

SNR Figures @ 2.6GHz (including implementation and ACK/NACK margins)

IoT for 100% RB Loading Ranges from 2-3dB for fractional power control – consider 3dB by default in LTE Link Budget


0.1 dB

1.0 dB

10.0 dB

100.0 dB

-6.0 dB -4.0 dB -2.0 dB 0.0 dB 2.0 dB 4.0 dB 6.0 dB 8.0 dB

Cell Edge SINR Target

IoT

Omni UE Antenna

Directional UE Antenna

Uplink Link BudgetWhat Determines the IoT for LTE?

The average IoT is dependent upon the targeted cell edge data rate (SINR)

The higher the cell edge SINR target, the higher the average IoT

Based on system levelsimulations:

Omni and Directional UEantennas

SINRs resulting in an IoT> 5-6dB is not consideredreasonable

Realistic Cell Edge SINR Operating Range


Uplink Link BudgetOverall MAPL & Cell Range

Overall MAPL for a given service:

dBdB

dBdBmdB

dBdBdBdBdBMaxTXdBj

HOGainarginShadowingMceMarginInterferenySensitivitnPenetratio

BodylossRxlossRxgainTxlossTxgainPMAPLdBm

Reference Sensitivity

Transmit Power

Losses and Margins

Gains

•= MAPL

Interferencecell radius

Maximum Allowable Pathloss

Reference Sensitivity

Max UE transmit Power

Gains - Losses- Margins

Interference marginextra cell interference


Uplink Link BudgetExample for Multiple Services

cell21dBjdB RlogKKMAPLMinMAPL

Dense Urban (2.6GHz) VoIP PS 64 PS 128 PS 256 PS 384 PS 512 PS 768 PS 1000 PS 2000

Required Data Rate 12.2 kbps 64 kbps 128 kbps 256 kbps 384 kbps 512 kbps 768 kbps 1000 kbps 2000 kbps

No. Resource Blocks Required 1 RB 2 RB 3 RB 5 RB 8 RB 10 RB 16 RB 20 RB 40 RB

MCS MCS 6 MCS 6 MCS 8 MCS 10 MCS 10 MCS 10 MCS 10 MCS 10 MCS 10

Used Bandwidth 180 kHz 360 kHz 540 kHz 900 kHz 1440 kHz 1800 kHz 2880 kHz 3600 kHz 7200 kHz

Target C/I -3.7 dB -3.6 dB -3.0 dB -2.4 dB -2.9 dB -3.1 dB -3.4 dB -2.9 dB -3.3 dB

eNode-B Noise Figure 2.5 dB 2.5 dB 2.5 dB 2.5 dB 2.5 dB 2.5 dB 2.5 dB 2.5 dB 2.5 dB

eNode-B Sensitivity -122.7 dBm -119.6 dBm -117.2 dBm -114.4 dBm -112.9 dBm -112.1 dBm -110.3 dBm -108.8 dBm -106.2 dBm

Antenna Gain 18.0 dBi 18.0 dBi 18.0 dBi 18.0 dBi 18.0 dBi 18.0 dBi 18.0 dBi 18.0 dBi 18.0 dBi

Cable & Connector Losses 0.5 dB 0.5 dB 0.5 dB 0.5 dB 0.5 dB 0.5 dB 0.5 dB 0.5 dB 0.5 dB

Body Losses 3 dB 0 dB 0 dB 0 dB 0 dB 0 dB 0 dB 0 dB 0 dB

Additional UL Losses 0 dB 0 dB 0 dB 0 dB 0 dB 0 dB 0 dB 0 dB 0 dB

Cell area coverage probability 95% 95% 95% 95% 95% 95% 95% 95% 95%

Overall standard deviation 8.0 dB 8.0 dB 8.0 dB 8.0 dB 8.0 dB 8.0 dB 8.0 dB 8.0 dB 8.0 dB

Shadowing Margin 8.6 dB 8.6 dB 8.6 dB 8.6 dB 8.6 dB 8.6 dB 8.6 dB 8.6 dB 8.6 dB

Handoff Gain 3.6 dB 3.6 dB 3.6 dB 3.0 dB 2.4 dB 2.0 dB 1.5 dB 1.1 dB 0.5 dB

Fast Fading Margin 0 dB 0 dB 0 dB 0 dB 0 dB 0 dB 0 dB 0 dB 0 dB

Penetration Margin 21 dB 21 dB 21 dB 21 dB 21 dB 21 dB 21 dB 21 dB 21 dB

Fixed IoT 3.0 dB 3.0 dB 3.0 dB 3.0 dB 3.0 dB 3.0 dB 3.0 dB 3.0 dB 3.0 dB

UE Antenna Gain 0 dBi 0 dBi 0 dBi 0 dBi 0 dBi 0 dBi 0 dBi 0 dBi 0 dBi

UE Max Transmit Power 23 dBm 23 dBm 23 dBm 23 dBm 23 dBm 23 dBm 23 dBm 23 dBm 23 dBm

MAPL 131.2 dB 131.1 dB 128.7 dB 125.3 dB 123.1 dB 122.0 dB 119.7 dB 117.8 dB 114.5 dB

UL Cell Range 0.53 km 0.53 km 0.46 km 0.37 km 0.32 km 0.30 km 0.25 km 0.23 km 0.18 km


Uplink Link BudgetFractional Power Control – Handling in LKB (4/4)

Respecting the SINR slope (dictated by the fractional power control parameters) means for services requiring very high SINR values that:

Substantial reductions in allowable UE transmit power are required

The corresponding impact on the link budget is substantial


Uplink Link BudgetPropagation Models

For 700, 850 or 900 MHz - Okumura-Hata:

K1 = 69.55 + 26.16 x log10(FMHz) - 13.82 x log10(Hb) - a(Hm) + Kc

a(Hm) = (1.1 x log10(FMHz) - 0.7) x Hm - (1.56 x log10(FMHz) - 0.8) medium-sized city

K2 = 44.9 -6.55*log10(Hb)

For AWS, 1.9GHz or 2.1GHz - COST-231 Hata:

K1 = 46.3 + 33.9 x log10(FMHz) - 13.82 x log10(Hb) - a(Hm) + Kc

K2 = 44.9 - 6.55 x log10(Hb)

For 2.6GHz - modified COST-231 Hata: as COST-231 Hata is limited to 1.5GHz to 2GHz

Based on measurements at higher frequencies (2.5GHz & 3.5GHz):

K1 = 46.3 + 33.9 x log10(2000) + 20 x log10(FMHz/2000) - 13.82 x log10(Hb) -a(Hm) + Kc

K2 = 44.9 - 6.55 x log10(Hb)


Uplink Link BudgetImpact of TMA (1/3)

Tower Mounted Amplifier (TMA) also called Mast Head Amplifier (MHA)

Impact on link budget

Slightly Reduce the global NoiseFigure

Compensate the cable losses

0.4dB DL insertion losses

Usage recommended for ULcoverage-limited scenarios

eNode-B

Dual TMA

Jumper Cable

Jumper Cable

TX / RX TXdiv / RXdiv

Duplexer

Duplexer Duplexer

Duplexer

LNALNA

Feeder

AntennaVertical

Polarisation


Tower Mounted Amplifier Impact of TMA (2/3)

Typical gain on uplink link budget (Macro site):

2.9dB gain for sites with 3dB cable losses

3.7 dB gain for sites with 4dB cable losses

Typical gain on uplink link budget (RRH site):

0.3dB gain for sites with 0.6dB cable losses

Note: TMA should not be considered for RRH sites

Friis formula to compute the overall noise figure of the receiver chain

with TMA:

With and

Where NFfeeder =-Gfeeder =Feeder Losses

10NF

element

element

10n 10G

element

element

10g

feederTMA

BNode

TMA

feederTMAoverall gg

1ng

1nnn

Typical TMA characteristics:

NFTMA =2 dB GTMA =12 dB

DL Insertion losses = 0.4dB


Tower Mounted Amplifier Impact of TMA (3/3)

Dense Urban (2.6GHz) PS 128 (no TMA) PS 128 (TMA)

Required Data Rate 128 kbps 128 kbpsNo. Resource Blocks Required 3 RB 3 RB

MCS MCS 8 MCS 8Used Bandwidth 540 kHz 540 kHz

Target C/I -3.0 dB -3.0 dBeNode-B Noise Figure 2.5 dB 2.4 dB

eNode-B Sensitivity -117.2 dBm -117.3 dBmAntenna Gain 18.0 dBi 18.0 dBi

Cable & Connector Losses 3.0 dB 0.2 dBBody Losses 0 dB 0 dB

Additional UL Losses 0 dB 0 dBCell area coverage probability 95% 95%

Overall standard deviation 8.0 dB 8.0 dBShadowing Margin 8.6 dB 8.6 dB

Handoff Gain 3.6 dB 3.6 dBFast Fading Margin 0 dB 0 dBPenetration Margin 21 dB 21 dB

Fixed IoT 3.0 dB 3.0 dBUE Antenna Gain 0 dBi 0 dBi

UE Max Transmit Power 23.0 dBm 23.0 dBmMAPL 126.2 dB 129.1 dB

UL Cell Range 0.39 km 0.47 km

No cable losses but 0.2dB jumper losses

Reduced Noise figure (based on Friis formula)

Around 2.9dB gain on MAPL for sites with 3dB cable losses


Common & Control Channel Considerations Overview

There are two main common and control channel considerations that should be assessed for an LTE network design to ensure that they will not limit the coverage. These include:

INTERNAL NOTE – Attach Procedure

ACK/NACK Transmission

Either punctured onto the Physical Uplink Shared Channel (PUSCH)

Or over the Physical Uplink Control Channel (PUCCH)


INTERNAL NOTE – Common & Control Channel Considerations Attach Procedure

This is the procedure that the UE must go through to Attach to an LTE network

eNBUE MME

RACH Preamble (1)

Grant and TA (2)

RRC Connection Request (3)

RRC Connection Setup (4)

RRC Connection Setup Complete (5)

SGW PGW

No MME Relocation

Attach request (6)

Authentication (optional)/ security (7-8)Create Default Bearer

Request (9) CDB Request (10)

Limiting Message



From a link budget perspective the limiting message from messages 1, 2, 3, 4, 5, 15 and 16 (that involve the air interface) must be considered to assess any link budget constraints

eNBUE MME

Attach accepted (13)

SGW PGW

Create Default Bearer Response (12)

CDB Response (11)

RRC Connection reconfiguration (14)

RRC Connection reconfiguration complete (15)

Attach complete (16)

No MME Relocation

1st UL bearer packet

Update Bearer Request (20)

Update Bearer Response (21)

1st DL bearer packet



Message 3 (RRC Connection Request)

1 resource block with QPSK rate 1/3 providing an average effective data rate of 20.8 kbps (after 5 HARQ transmissions)

SINR requirement = 0.7dB(including margins)

UL link budget

Dense Urban

2.6GHz band

Attach LKB Can be Limiting Depending on Cell Edge Rate

Target


Common & Control Channel Considerations ACK/NACK Transmission

DL transmission requires a steady stream of ACK transmissions over the UL to acknowledge the DL packets

Correct ACK reception iscritical for optimizing the DLefficiency

ALU punctures ACK over thePUSCH initially and over thePUCCH in the longer term

ACK/NACK Transmission:

1 RB, QPSK, SINR -3.4dB(PUSCH) & -4.2dB (PUCCH)

UL LKB for Urban, 2.6GHz band

ACK Is Never Foreseen to Limit UL Coverage


LTE Link Budgets

Downlink Link Budget Considerations


Downlink Link BudgetRationale Behind Downlink LKB Formulation (1/3)

1. DL Cell range defined by UL cell edge service link budget

2. DL throughputs computed for coverage probabilities associated with each corresponding UL service

3. Geometry distribution used for determining the cell edge throughput



The above example illustrates the detailed DL Link Budget on the subsequent slides …

Urban morphology, indoor 0dBi omni UE configuration, cell range fixed for UL 128kbps, 100% adjacent cell DL RB Loading, No TMA

Note: The diagram is not to scale and doesn’t include all rates

RangeUL_Guar_Serv

128kbps (3RB) - guaranteed at cell edge

256kbps (5RB)

512kbps (10RB)

UL Rates

DL Rates

3921kbps (50RB)

8623kbps (50RB)

1323kbps (50RB)



Uniform power per RB is assumed on the DL

DL performances extracted from link level simulations

The optimal MCS is selected for given number of RB to maximize throughput while ensuring a 20% initial BLER

Only TxDiv is assumed for referenced DL link level simulations

As the DL link budget is focusing on cell edge performances it is considered that the rank and geometry are insufficient to justify Spatial Multiplexing (SM)

Where a relatively low rate is guaranteed on the UL at cell edge, e.g. 512kbps) the relative UL cell ranges for the high UL rates will be very small and thus the corresponding DL SINRs will be relatively high due to the reduced coverage reliability –in such cases there is some justification for consideration SM performances (not yet incorporated here)


Downlink BudgetExample: 10MHz BW

Dense Urban (2.6GHz) PS 128 PS 256No. Resource Blocks 50 RB 50 RB

Used Bandwidth 9000 kHz 9000 kHzUE Noise Figure 7 dB 7 dB

eNode-B Antenna Gain 18 dBi 18 dBiCable & Connector Losses 0.5 dB 0.5 dB

Body Loss 0 dB 0 dBPenetration Margin 21 dB 21 dB

Limiting UL Cell Range 0.46 km 0.46 km# DL Tx Paths 2 paths 2 paths

Total DL eNode-B Tx Power / Path 30 W 30 W% DL Power for PDSCH 80% 80%

Max eNode-B Tx Power / Service 46.8 dBm 46.8 dBmUE Antenna Gain 0 dBi 0 dBi

Adjacent Cell Loading 100% 100%UL Service Cell Range 0.46 km 0.37 km

DL Path Loss @ UL Cell Edge 129.1 dB 125.7 dBTotal DL Losses @ UL Cell Edge 150.6 dB 147.2 dB

DL Cell Area Coverage Probability 95% 61%Geometry at UL Service Cell Range -4.9 dB -0.1 dB

Desired Signal -85.8 dBm -82.3 dBmAdjacent Cell Signal -80.9 dBm -82.2 dBm

Noise -97.5 dBm -97.5 dBmCell Edge SINR -5.0 dB -0.2 dB

Optimal MCS MCS 2 MCS 7Data Rate at UL Service Cell Edge 1323 kbps 3921 kbps

Cell Range for Limiting UL Service (128kbps)

Cell Range for Equivalent UL Service (256kbps)

Coverage Probability for DL service

95% x (0.36)2 / (0.46)2

Equivalent UL Service
















% of total DL power dedicated to PDSCH

Geometry at the corresponding UL service range

The cell edge SINR


Downlink BudgetDL Power Settings

Depending on the OAM power offset settings for the Resource Elements (RE) of different channel types we can compute the Average PDSCH Power / OFDM Symbol

Example below for 10MHz, 2 x 40W PA Power

Average % power / symbol allocated to PDSCH RE’s 32.1 / 40 = 80.2%


Downlink BudgetGeometry & SINR (1/2)

Geometry distributions from system simulations

A range of UE configurations, bothomni and, directional UEs (fixed wireless)

Examples in LKB are for coveragereliabilities of 95% and 61%

Yield Geometries of -3.9 & 4.7dBrespectively

95% Coverage Reliability

Geometry-3.9dB

Geometry Distributions (Different UE Configs)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

-5.0 dB -1.0 dB 3.0 dB 7.0 dB 11.0 dB 15.0 dB 19.0 dB 23.0 dB

Geometry

CDF

Outdoor - 2 dBi - OmniOutdoor - 4 dBi - OmniOutdoor - 4 dBi - Direc.Outdoor - 6 dBi - Direc.Outdoor - 8 dBi - Direc.Outdoor - 10 dBi - Direc.Indoor - 0 dBi - OmniIndoor - 2 dBi - OmniIndoor - 4 dBi - Omni

61% Coverage Reliability

Geometry4.7dB

An additional 1dB is subtracted from these geometry

values to align with field expectations

AllSiteAdjacent

SiteServing

PowerRx

PowerRxGeometry


Downlink BudgetGeometry & SINR (2/2)

PDSCH SINR for a defined cell range and coverage reliability:

PDSCHSINR = PDSCHRx / [ PDSCHRx – Geometry + Thermal Noise]

Where:

PDSCHRx = PowerPDSCH – Total DL Losses

PowerPDSCH = PowerMax PA x Power FractionPDSCH x RBService / RBMax

– Power FractionPDSCH is the average fraction of the total power allocated to PDSCH Resource Elements (REs) per symbol across all RB’s

Thermal Noise = 10 x log10( F x Nth x NRB x WRB )– F: eNode-B Noise figure in dB– Nth: Thermal noise density, 10log(Nth) =-174 dBm/Hz– NRB: Number of resource blocks (RB) required to reach a given data rate– WRB: Bandwidth of one Resource Block
















Max # RB for the bandwidth is assumed by default

Corresponding L1 Throughput for #RB, MCS and SINR

The optimal MCS for the #RB and SINR


Downlink Link BudgetSINR Performances - Overview

Like the UL the DL SINR Performances depends on:

eNode-B equipment performance

Radio conditions (multipath fading profile, mobile speed)

Receive diversity (2-way by default or optional 4-way)

Targeted data rate and quality of service

The Modulation and Coding Scheme (MCS)

Max allowed number of HARQ transmissions

HARQ Operating Point – 20% BLER for 1st HARQ Transmission considered by default

Derived from link level simulations

Note: Currently the Link Level Simulations referenced in the DL LKB are for EVehA3km/h, 2x2 TxDiv


Downlink Link BudgetSINR - Selection of Optimal SINR Figures

Based on a set of link level simulation results:

Full range of MCS values

Full range of # RB’s

Example for Downlink 50RB, 10MHz

Bandwidth (2x2 MIMO)

LTE DL 2x2 MIMO. EVA-3km/hr

0

10000

20000

30000

40000

50000

60000

-10 -5 0 5 10 15 20 25 30 35 40 45 50

SNR (dB)

Th

roug

hpu

t (k

bps)

MCS = 0 MCS = 1

MCS = 2 MCS = 3

MCS = 4 MCS = 5

MCS = 6 MCS = 7

MCS = 8 MCS = 9

MCS = 10 MCS = 11

MCS = 12 MCS = 13

MCS = 14 MCS = 15

MCS = 16 MCS = 17

MCS = 18 MCS = 19

MCS = 20 MCS = 21

MCS = 22 MCS = 23

MCS = 24 MCS = 25

MCS = 26 MCS = 27

MCS = 28 T'put (kbps)


Downlink Link BudgetDownlink Performance Analysis (1/3)

Downlink Link Level Results for:

25 RB, MCS 28, TxDiv and 5MHz Bandwidth

0 kbps

2000 kbps

4000 kbps

6000 kbps

8000 kbps

10000 kbps

12000 kbps

14000 kbps

16000 kbps

12.00 dB 14.00 dB 16.00 dB 18.00 dB 20.00 dB 22.00 dB 24.00 dB 26.00 dB

SINR

Thro

ugh

put

0.0%

20.0%

40.0%

60.0%

80.0%

100.0%

120.0%

BLER

Throughput

BLER_0 20% BLER19

.4dB

SIN

R

12Mbps Throughput




25 RB, 1-28 MCS, TxDiv and 5MHz Bandwidth

-5dB cell edge SINR

0 kbps

2000 kbps

4000 kbps

6000 kbps

8000 kbps

10000 kbps

12000 kbps

14000 kbps

0 5 10 15 20 25

MCS Index

Thro

ughp

ut

-10 dB

-5 dB

0 dB

5 dB

10 dB

15 dB

20 dB

25 dB

SIN

R

Throughput

SINR

-5dB Cell Edge SINR Target

MCS 1

660 kbps T’put




1 to 25 RB, All MCS, TxDiv and 5MHz Bandwidth

-5dB cell edge SINR

1 kbps

10 kbps

100 kbps

1000 kbps

2 RB 7 RB 12 RB 17 RB 22 RB

# Resource Blocks

Thr

ough

put

MCS 0

MCS 1

MCS 2

MCS 3

MCS 4

MCS 5

MCS 6

Mod

ulat

ion

& C

odin

g Sc

hem

e

Throughput

Throughput / RB

MCS


Downlink BudgetExample: 10MHz BW (Multiple Services)

Dense Urban (2.6GHz) PS 128 PS 256 PS 512No. Resource Blocks 50 RB 50 RB 50 RB

Used Bandwidth 9000 kHz 9000 kHz 9000 kHzUE Noise Figure 7 dB 7 dB 7 dB

eNode-B Antenna Gain 18 dBi 18 dBi 18 dBiCable & Connector Losses 0.5 dB 0.5 dB 0.5 dB

Body Loss 0 dB 0 dB 0 dBPenetration Margin 21 dB 21 dB 21 dB

Limiting UL Cell Range 0.46 km 0.46 km 0.46 km# DL Tx Paths 2 paths 2 paths 2 paths

Total DL eNode-B Tx Power / Path 30 W 30 W 30 W% DL Power for PDSCH 80% 80% 80%

Max eNode-B Tx Power / Service 46.8 dBm 46.8 dBm 46.8 dBmUE Antenna Gain 0 dBi 0 dBi 0 dBi

Adjacent Cell Loading 100% 100% 100%UL Service Cell Range 0.46 km 0.37 km 0.30 km

DL Path Loss @ UL Cell Edge 129.1 dB 125.7 dB 122.4 dBTotal DL Losses @ UL Cell Edge 150.6 dB 147.2 dB 143.9 dB

DL Cell Area Coverage Probability 95% 61% 40%Geometry at UL Service Cell Range -4.9 dB -0.1 dB 3.3 dB

Desired Signal -85.8 dBm -82.3 dBm -79.1 dBmAdjacent Cell Signal -80.9 dBm -82.2 dBm -82.4 dBm

Noise -97.5 dBm -97.5 dBm -97.5 dBmCell Edge SINR -5.0 dB -0.2 dB 3.2 dB

Optimal MCS MCS 2 MCS 7 MCS 10Data Rate at UL Service Cell Edge 1323 kbps 3921 kbps 8623 kbps


Downlink Link BudgetSummary

The downlink link budgets presented here are indicative of what rates are achievable within the corresponding UL service coverage areas

LTE coverage is not considered to be limited by the DL for typical eNode-B output powers and deployment scenarios with a 23dBm UE output power, link budgets should remain uplink limited

It is important to understand that:

DL cell edge performances are strongly dependent upon scheduler parameters (e.g. tuning of the fairness of the proportional fair scheduler algorithm) or the available bandwidth (e.g. 10MHz vs 5MHz)

DL performances in the link budget are based only on long term average PDSCH SINR values and do not account for dynamic channel variations that can be addressed with frequency selective scheduling functionalities

Better estimates of DL performances can be achieved by means of:

System level simulations and/or Radio Network Planning (RNP) analysis


Downlink Link BudgetRequired DL Output Power ?

A series of system simulation studies were performed to assess the required Power Amplifier (PA) sizing for 3 different important cases

700 MHz (10 MHz), 2.1 GHz (10 MHz), 2.1 GHz/AWS (5 MHz) and 2.6 GHz (20 MHz)

All scenarios considered 2x2 MIMO on the DL and 2RxDiv on the UL

In principle, all studies concluded the following:

Spectrum efficiency for “reasonable” cell sizes is relatively invariant to reasonable choices for PA sizes

Edge rates become much more sensitive to the choice of power at large cell radiuses


Downlink Link BudgetDownlink PA Sizing for LTE – Conclusions

Carrier Bandwidths PA Power

1.4 MHz 2 x 10 W

3.0 MHz 2 x 10 W

5.0 MHz 2 x 20 W

10.0 MHz 2 x 30 W

15.0 MHz 2 x 40 W

20.0 MHz 2 x 40 W

Recommendations from study

(independent of frequency)


RF Design


LTE eNode-B DimensioningKey Issues to be considered

Cell edge coverage expectations + depth of coverage

Target operating frequency band + propagation assumptions

Overlay versus Greenfield deployment

Antenna system sharing requirements (impact on coverage + optimization constraints)

Radio features, e.g. TMA, RRH, ICIC

Cove

rage

Subscriber usage profile

Subscriber forecast

Spectrum constraints

Peak throughput requirements

Radio features, e.g. ICIC

Capa

city


Rollout Phase Site Field Positioning Principles

Based on Site Count (from RF dimensioning process)

Sites positioned to satisfy – RS coverage target (from LB for a target area reliability)– Capacity requirement

Placed either manually or utilizing Automatic Cell Planning (ACP) tools

Site Sharing Approach:

The first and quickest approach without RNP is to overlay existing sites with LTE– A 1:1 mapping is most appropriate where the overlaid network is at a

frequency band close to LTE band

Site overlay optimized with the aid of RNP predictions with an accurate propagation model

– Sites can be added or deleted where there is limited or excess coverage, respectively

– Analysis performed at the same time as antenna azimuth optimization (see next slide)


Rollout Phase RF Optimization Criteria

Azimuth optimization and tilt optimization are the main rules to optimize the network in order to have the best radio environment before implementing any features.

The aim are

Optimize coverage in order to reach RSRP targets

To reduce the number of servers covering the same area in order to avoid excessive overlapping.

– This minimize interference without impacting coverage, improve SINR so network performances like

– Throughput – Capacity– Frequency re-use efficiency


Rollout Phase RSRP target

RS-RSSI: total power transmitted dedicated for Reference signal during one OFDM symbol duration

Currently in Atoll it is more RS-RSSI is calculated, and the total power dedicated to RS is 1/6 of Max power. This approach is not 100% of the time in line wit power settings on the field

LA0.x for a 30W PA power energy per RE for RS is 14.9 dBm. Considering 10MHz bandwidth 100 RE are used to calculate RS-RSSI, so total power dedicated to RS over one OFDM symbol is 34.9dBm, but Atoll calculates 30W/6, so 37dBm, so to do the right calculation for this configuration max power set in Atoll should be 43dBm instead of 45dBm.


Rollout Phase RSRP target

LA1.0 for RRH 30W PA power energy per RE for RS is 16.2 dBm. Considering 10MHz bandwidth 100 RE are used to calculate RS-RSSI, so total power dedicated to RS over one OFDM symbol is 36.2dBm, but Atoll calculates 30W/6, so 37dBm, so to do the right calculation for this configuration max power set in Atoll should be 44dBm instead of 45dBm.

LA1.0 for TRDU 40W PA power energy per RE for RS is 18.2 dBm. Considering 10MHz bandwidth 100 RE are used to calculate RS-RSSI, so total power dedicated to RS over one OFDM symbol is 38.2dBm, Atoll calculates 40W/6, so 38dBm, so it is ok

3GPP RSRP definition:

Reference signal received power (RSRP), is determined for a considered cell as the linear average over the power contributions (in [W]) of the resource elements that carry cell-specific reference signals within the considered measurement frequency bandwidth.



Outdoor RSRP target depending on environment and frequencies for UL PS 128 service and UL PS 256, considering 45dBm PA power and 14.9 dBm Reference signal Tx power per RE. RSRP value does not depends on the number of transmit

DL RS EIRP per RE and per transmit:

30.9dBm @ 2600MHz/2100MHz/AWS/1900MHz/1800MHz with 18dBi antenna gain & 2dB cable losses

30.9dBm @ 900MHz/850MHz with 17dBi antenna gain & 1dB cable losses

28.9dBm @700MHz with 15dBi antenna gain & 1 dB cable losses



Currently the calculation done in 9155 is the sum of all Reference signal resource elements power transmitted in a same OFDM time period over all the bandwidth. This approach is not in line with 3GPP as 3GPP specify the linear average of reference signal resource elements.

To compensate this error the following work around must be followed and based on the same analysis done for RS-RSSI calculation

LA0.x for RRH 30W PA power energy per RE for RS is 14.9 dBm. – For 5MHz bandwidth set in Cell table Max power column:

eNode-B PA power -19dB– For 10MHz bandwidth set in Cell table Max power column:


eNode-B PA power -25dB



LA1.0 for RRH 30W PA power energy per RE for RS is 16.2 dBm. – For 5MHz bandwidth set in Cell table Max power column:




LA1.0 for TRDU 40W PA power energy per RE for RS is 18.2 dBm. – For 5MHz bandwidth set in Cell table Max power column:






The method proposed is to:

Set indoor penetration losses in 9155 clutter table

Use the UL Link Budget Available Path loss with 0dB penetration losses set in the LB for the dimensioning service selected,

Design RSRP = RS per RE EIRP+ ANT_GAIN – Available Uplink Pathloss – indoor losses

where:

– RS per RE EIRP = Reference signal EIRP per resource element , it is automatically calculated by 9155 when the work around specified above is followed

– ANT_GAIN = Node-B antenna gain– Available Uplink Pathloss: UL available pathloss calculated with the link budget when

penetration loss is set to 0dB

The RSRP target values specified in slide , have been defined with this approach.

If the user apply this approach, the following recommendation must be respected

Select “indoor loss” icon in 9155 coverage study Do not select “shadowing taken into account “ icon as it is already done in RSRP target calculated below

149 | Presentation Title | Month 2008 149 | Presentation Title | Month 2008

RF optimization criteria

Overlapping optimization

The following rules are not technology specifics, and their efficiency have already been measured on GSM, W-CDMA networks.

Pollution and interference analysis– Within 4dB of the best server

– number of servers should ≤ 4 – % area with 4 servers should be < 2%.– % of area with 2 servers should be < 30%.

– Within 10dB of the best server– number of servers should ≤ 7– % of area with 7 servers should be < 2%.

– High signal level overlap analysis:– Increase the design threshold for the covered area by 10dB– % of 3 servers in the design area should not exceed 10%..– Example: if the RS design threshold is -85dBm, a number of server’s

analysis is done with a threshold equal to -75dBm.



SINR target

This target can be used with 9155 RNP tool, but it is not 100% sure that it can be measured on the field with high accuracy as it is not 3GPP measurement criteria.

In 9155 SINR can be calculated based on reference signal, or PDSCH, and for loaded cases it provides the same results as power per RE RS= power per RE PDSCH

The SINR target value depends on the traffic load:– 95% of the design area should have SINR ≥ -5dB, with 100% DL load– 95% of the design area should have a SINR ≥-2dB with 50% DL load

SINR does not depends on number of transmits



RSRQ target

RSRQ= N*RSRP/RSSI where RSSI is all the power received in the N resource blocks used bandwidth during the same time period where RSRP is measured.

RSRQ depends on the number of transit, as RSSI value depends on it, and not RSRP

RSRQ target value depends on the traffic load:

1 transmit : – 95% of the design area should have RSRQ ≥ -17dB, with 100% DL load– 95% of the design area should have RSRQ ≥ -14dB, with 50% DL load

2 transmits : – 95% of the design area should have RSRQ ≥ -20dB, with 100% DL load– 95% of the design area should have RSRQ ≥ -17dB, with 50% DL load

4 transmits : – 95% of the design area should have RSRQ ≥ -23dB, with 100% DL load– 95% of the design area should have RSRQ ≥ -20dB, with 50% DL load



These targets are been obtained on several well known environments ; where a very good optimization has been done in W-CDMA due to critical inter-site distance : 400m. Same RNP environment has been re-used for LTE predictions without changing anything to evaluate the best SINR & RSRQ reachable in different full traffic load condition.

The RNP prediction and RF optimization done for the different trials in US and Europe confirm that these targets can be reach and are a good way to optimize throughput and reduce interferences.

Overlapping criteria, RSRQ target and SINR target defined above are in line to provide the same RF design. They allow managing interferences in order to obtain a RF network design able to support the best throughput .

10Mbps in cell center for mono-user when all surrounded cells have 100% load

1.5Mbps at cell edge in mono-user for 10MHz bandwidth when all surrounded cells have 100% load



Neighbors & Cell ID planning criteria

Cell id is required to identify each cell, a cell id is the combination of one of the 3 sequences supported by P-SCH and the group Id supported by S-SCH.

– So Realizing a cell id planning = realizing P-SCH planning and S-SCH planning– The strategy recommended is to use the same S-CH per site which induces

that each sector uses a different P-SCH sequence

This distance depends on propagation path loss, the environment and the frequency.

The main criteria are the following one:

Considering two cells cell A and cell B, on the same frequency carrier using the same cell ID, the distance between those must satisfy the following criterias:

– RSRP criteria– At cell A edge (RSRPcellA ≤ -115dBm) : RSRPcellA ≥ : RSRPcellB + 10dB– At cell B edge (RSRPcellB ≤ -115dBm): RSRPcellB ≥ : RSRPcellA + 10dB

– RSRQ criteria for 100% load case ( 2 transmits)– At cell A edge (RSRQcellA ≤ -20dB) : RSRQcellA ≥ : RSRQcellB + 10dB– At cell B edge (RSRQcellB ≤ -20dB): RSRQcellB ≥ : RSRQcellA + 10dB



Distance criteria

Dense urban/ urban – 2km @ 2600MHz considering 600m cell radius– 2,4km @ 1800MHz and 2100MHz considering 700m cell radius– 5,5km @ 850MHz and 900MHz considering 1,7km cell radius– 6Km @ 700MHz considering 1,9km cell radius

Suburban– 6km @ 2600MHz considering 1,8km cell radius– 7km @ 1800MHz and 2100MHz considering 2,2km cell radius– 18km @ 850MHz and 900MHz considering 5,5km cell radius– 20Km @ 700MHz considering 6km cell radius

Rural– 17km @ 2600MHz considering 6km cell radius– 21km @ 1800MHz and 2100MHz considering 7km cell radius– 60km @ 850MHz and 900MHz considering 18km cell radius– 65Km @ 700MHz considering 20km cell radius


Hard Handover


Hard Handover


Hard HandoverPreparation Phase


Hard HandoverExecution Phase

Hard HandoverCompletion phase


Hard HandoverExecution time

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