Atoll_3.3.0_LTE

Forsk 2015 Confidential Do not share without prior permission

LTE Features Atoll 3.3.0

Slide 1

1. LTE Concepts

2. LTE Planning Overview

3. Modelling a LTE Network

4. LTE Predictions

5. Neighbours Allocation

6. Automatic Resource Allocation

7. MIMO Features

Forsk 2015 Slide 2 Confidential Do not share without prior permission

Training Programme

1. LTE Concepts

Overview

OFDM Definition

Advanced OFDM: OFDMA

Benefits of OFDM/OFDMA

Multiple Access Techniques and Duplexing Methods

LTE Radio Interface

Forsk 2015 Confidential Do not share without prior permission Slide 3

What is 4G?

Evolution of 3GPP standards

Release 99: UMTS FDD (3G)

Release 4: UMTS TDD + FDD repeaters (3G)

Release 5: HSDPA (3.5G)

Release 6: HSUPA (enhanced uplink) + MBMS (3.5G)

Release 7: HSPA+ (2x2 MIMO, higher order modulations, etc.) (3.75G)

Release 8: LTE FDD and TDD (3.9G) + HSPA+ multi-carrier

Release 10: LTE advanced (4G)


Technologies

3GPP Release

5/6 3GPP Release 99/4

3GPP Release

7/8

LTE 3GPP Release 8

LTE Adv. 3GPP

Release 10

WCDMA 384 kbps downlink

128 kbps uplink

HSDPA/HSUPA 14 Mbps peak downlink

5.7 Mbps peak uplink

HSPA+ 42,2 Mbps peak downlink

11 Mbps peak uplink

LTE 100 Mbps peak downlink

50 Mbps peak uplink

LTE Adv. 100 Mbps to 1Gbps

peak downlink

WCDMA WCDMA + Enhanced architecture

+ Higher order modulations

WCDMA + MIMO

+ Dual-carrier

OFDMA SC-FDMA

MIMO

+ Carrier aggregation (DL/UL) + HetNets

+ enhanced MIMO (8*8)

Slide 4

OFDM Frequency and Time Domains

What is OFDM ?

OFDM = Orthogonal Frequency Division Multiplexing

Frequency domain organization

Advanced form of Frequency Division Multiplexing (FDM)

Principle:

Wideband channel split into multiple orthogonal narrowband radio carriers (subcarriers)

Subcarriers are spaced in a manner that the centre of each subcarrier corresponds to a zero crossing point of the neighbouring subcarriers

Good spectral efficiency compared to FDM systems


OFDM Frequency and Time Domains

Time domain organization

Adjustable guard period referred to as cyclic prefix

Used to fight against multipath effects (delay spread)

Two configurations depending on the environment

Normal cyclic prefix: 4.7 us

Extended cyclic prefix: 16.7 us

Typical values of delay spread:

Open environment: 0.2 us

Suburban: 0.5 us

Urban: 3 us

Hilly area: 3-10 us


Advanced OFDM: OFDMA

OFDM : Orthogonal Frequency Division Multiplexing

OFDM allocates users in time domain only

The entire channel bandwidth is allocated to one user

OFDMA : Orthogonal Frequency Division Multiple Access

OFDMA allocates users in time and frequency domains

Several users served at once


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Benefits of OFDM/OFDMA

OFDM(A) summary:

No ICI and ISI:

No intra-cell interference in theory

Possibility to support less robust modulations like 16QAM, 64QAM for higher throughput !


Narrowband orthogonal subcarriers

Negligible inter-carrier interference (ICI)

No frequency selective fading

Long symbol durations + cyclic prefix

Negligible inter-symbol interference (ISI)

Multiple Access Techniques and Duplexing Methods

OFDMA in DL

Each subcarrier carries one specific data symbol (QPSK, 16QAM...)

SC-FDMA in UL (OFDMA variant)

Single-Carrier Frequency Division Multiple Access

Each subcarrier carries information of all data symbols

Technique well suited to LTE UL requirements

Lower PAPR*

Power consumption limited

LTE can be deployed in FDD and TDD


*PAPR: Peak to Average Power Ratio

LTE Radio Interface

LTE channel structure

A channel is composed of more than 1 frequency block (FB)

Fixed width = 180 kHz (LTE system level constant)

1 frequency block over 1 slot = 1 resource block (RB)

Each FB is composed of many subcarriers

Two subcarrier widths possible: 15 kHz, 7.5 kHz (specified for MBMS/SFN services)

1 FB = 12 SCa of 15 kHz OR 24 SCa of 7.5 kHz

1 subcarrier over 1 SD (symbol duration) = 1 resource element (RE)


LTE PHY layer supports a wide range of bandwidths

Spectrum flexibility

LTE Channel Structure


Channel bandwidth

Subcarrier spacing

Number of FBs

Number of subcarriers

Sampling frequency

FFT size

1.4 MHz

15 kHz

(7.5 kHz for MBMS)

6 72 1.92 MHz

(1/2 x 3.84) 128

3 MHz 15 180 3.84 MHz (1 x 3.84)

256

5 MHz 25 300 7.68 MHz (2 x 3.84)

512

10 MHz 50 600 15.36 MHz (4 x 3.84)

1024

15 MHz 75 900 23.04 MHz (6 x 3.84)

1536

20 MHz 100 1200 30.72 MHz (8 x 3.84)

2048

LTE Frame Structure

Time domain structure (for both UL and DL)

Specific frame structures for TDD and FDD

1 frame = 10 ms = 2 half-frames (TDD) = 10 sub-frames or TTI (each 1 ms) = 20 slots (each 0.5 ms)

1 slot (0.5 ms) = 6 or 7 symbol durations (depending on the cyclic prefix duration)

1 FB over 1 sub-frame (1ms) = smallest unit that can be allocated by the scheduler (scheduling block)

Control channels transmitted on sub-frames 0 and 5 (always DL)


LTE Frame

10 ms

SF 0 SF 1 SF 9 ..

1 ms

Slot 0 Slot 1 Slot 2 Slot 3 Slot 18 .. Slot 19

0.5 ms

OFDM Symbol 0 C

P OFDM

Symbol 1 CP

OFDM Symbol 3 C

P OFDM

Symbol 4 CP

OFDM Symbol 5 C

P OFDM

Symbol 6 CP

OFDM Symbol 2 C

P

Slide 12

eNode-B

Physical Channels


HARQ feedback,

CQI reporting,

UL scheduling request,

CQI reporting for MIMO related feedback

Random access

Traffic

Pilot (channel estimation),

slot/frame synchronization and

cell identification

Traffic, MBMS,

system information,

paging

HARQ feedback,

transport format,

UL scheduling grants,

DL resource allocation

Slide 13

OFDMA LTE Frame (DL)

Structure of a resource block

Frame structure of type I (FDD), 1 antenna port, F = 15 kHz

Standard frequency block:

Any frequency block within the centre 6 frequency blocks:

Legend:

Downlink reference signals

PBCH (Physical Broadcast Channel)

PSS (Primary Synchronisation Signal)

SSS (Secondary Synchronisation Signal)

PDCCH / PHICH / PCFICH (Physical - Downlink Control / HARQ Indicator / Control Format Indicator - Channels)

PDSCH (Physical Downlink Shared Data Channel)

RBs allocated to mobiles are not necessarily adjacent interference coordination


OFDMA LTE Frame (DL)


OFDM symbol 0 C

P OFDM

symbol 1 CP

OFDM symbol 3 C

P OFDM

symbol 4 CP

OFDM symbol 5 C

P OFDM

symbol 6 CP

OFDM symbol 2 C

P

Legend:

Downlink reference signals

PBCH

PSS

SSS

PDCCH / PHICH / PCFICH

PDSCH

1 subframe = 2 slots (1 ms)

1 frame (10 ms) = 10 subframes (1 ms) = 20 slots (0.5 ms)

SF 0 SF 1 SF 2 SF 3 SF 4 SF 5 SF 6 SF 7 SF 8 SF 9

7 OFDM symbols at normal CP per slot (0.5 ms)

0 1 2 3 4 5 6 0 1 2 3 4 5 6

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Slide 15

SC-FDMA LTE Frame (UL)


Legend:

UL DRS (Uplink Demodulation Reference Signal)

UL SRS (Uplink Sounding Reference Signal)

PUCCH (Physical Uplink Control Channel) (incl. HARQ feedback and CQI reporting)

Demodulation Reference Signal for PUCCH

PUSCH (Physical Uplink Shared Channel)

1 subframe = 2 slots (1 ms)

SF 0 SF 1 SF 2 SF 3 SF 4 SF 5 SF 6 SF 7 SF 8 SF 9

0 1 2 3 4 5 6 0 1 2 3 4 5 6

1 frame (10 ms) = 10 subframes (1 ms) = 20 slots (0.5 ms)

180 kHz

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Slide 16

OFDM symbol 0 C

P OFDM

symbol 1 CP

OFDM symbol 3 C

P OFDM

symbol 4 CP

OFDM symbol 5 C

P OFDM

symbol 6 CP

OFDM symbol 2 C

P

7 OFDM symbols at normal CP per slot (0.5 ms)

1. LTE Concepts



4. LTE Predictions



7. MIMO Features


Training Programme


LTE Features Supported in Atoll

LTE Planning Workflow in Atoll



Atoll fully supports LTE/LTE-A networks

Various E-UTRA frequency bands

Scalable channel bandwidths (from 1,4 MHz to 20 MHz)

Support of TDD and FDD frame structures

Normal and extended cyclic prefixes

Downlink and uplink control channels and overheads

Downlink and uplink reference signals, PSS, SSS, PBCH, PDCCH, PUCCH, etc.

Physical Cell IDs implementation

Network capacity analysis using Monte-Carlo simulations

RSRP, RSSI and RSRQ support in predictions and simulations




Inter-cell interference coordination (ICIC) support

Hard FFR (Fractional Frequency Reuse),

Time-switched FFR,

Soft FFR,

Partial soft FFR

eICIC (enhanced ICIC)

Support of fractional power control (UL)

Modelling of multi-layer heterogeneous networks (HetNets)

Small Cells, Relay nodes

Layers and eICIC features

Services can be mapped to QoS Class Identifiers (QCI)

Beamforming modelling (smart antennas)

Possibility of fixed subscriber database for fixed applications



Carrier Aggregation up to 5 carriers of 20 MHz

Dynamic Multiple Input Multiple Output (MIMO) systems

Transmit and receive diversity

Single-user MIMO or spatial multiplexing

Dynamic MIMO switching

Modelling of Multi-User MIMO (MU-MIMO)

AAS (Active Antenna Systems) with beamforming

Tools for automatic resource allocation

Automatic allocation of neighbours

Automatic allocation of Physical Cell IDs (PCI)

Automatic allocation of frequencies

PRACH RSI (root sequence indexes)

Network verification using drive test data

Specific module (AFP)



LTE Planning Workflow in Atoll


Open an existing project or create a new one

Prediction study reports

Traffic maps

Network configuration - Add network elements

- Change parameters

User-defined values

Automatic or manual neighbour allocation

Basic predictions (Best server, signal level)

Monte-Carlo simulations

Signal quality and throughput predictions

Cell load conditions

Subscriber lists

And/or

Frequency plan analysis

Automatic or manual frequency planning

Automatic or manual Physical Cell ID and PRACH Root Sequence Index planning

ACP

Slide 22

1. LTE Concepts



4. LTE Predictions



7. MIMO Features


Training Programme


Global Settings

Frequency bands and channels definition

Global LTE frame definition

Radio Parameters

Sites

Transmitters

Cells

Multi-layer Networks (HetNets)

HetNets Configuration

eICIC

Relay links


Global Settings (1/2)

Frequency bands and channels definition

Atoll can model multi-band networks within the same document

2 duplexing methods available: FDD and TDD

Bandwidths from 1,4 MHz to 20 MHz supported


Global LTE frame definition

System-level constants (hard-coded)

Width of a resource block (180 kHz)

Frame duration (10 ms)

Other control channel overheads defined by 3GPP

Reference signals, PSS, SSS, PBCH, etc.

Global Settings (2/2)


TDD option only: Special subframe

selection

Number of SD for PDCCH (from 0 to 4) carrying DL

and UL resource allocation information

Normal (default) or extended cyclic prefix at 15 kHz, 7 SD/slot (normal), or 6 SD/slot (extended)

Average number of resource blocks for

PUCCH

Slide 26

Advanced Settings (1/2)

Downlink Cell-specific Reference Signals

Reference Signal Power Boost

With more than one antenna port

Each antenna uses different resource elements to transmit reference signals

Resource elements of one antenna port that correspond to reference signal transmission on another antenna port are not used (DTX)

Different LTE equipment and vendors may support different methods for reusing the energy corresponding to the unused resource elements

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Antenna port 0


Antenna port 1


Antenna port 2


Antenna port 3


Advanced Settings (2/2)

Downlink Transmit power calculation

0-Max Power defined manually in the cell table. The energy of the unused resource elements is distributed on the downlink channels.

1-RS EPRE defined manually. The Max Power will automatically be calculated

2-Max Power defined manually in the cell table. The energy of the unused resource elements is allotted to reference signal resource elements only (RS Power Boost = 3dB for 2 antennas and 6dB for 4 antennas)

3-Max Power defined manually in the cell table. The energy of the unused resource elements is lost

4-Max power and RS EPRE defined manually in the cell table.


Radio Parameters Overview

Sites

Characterized by their X (longitude) and Y (latitude) coordinates

Transmitters

Activity

Antenna configuration (model, height, azimuth, mechanical/electrical tilts...)

UL and DL losses / UL noise figure

Propagation (model, radius and resolution)

Cells

Frequency band & channel

Layer

Cell Type

Physical Cell ID

Power definition of DL channels

Min. RSRP

DL and UL traffic loads

Diversity support (MIMO)

Neighbours


Presented in the General Features course

Slide 29

Specific parameters for LTE technology

Transmitter Parameters

Transmitter parameters


Propagation settings Antenna configuration and losses parameters

Antenna configuration

DL and UL total losses,

UL noise figure

Cell Parameters

Main parameters

Cell activity

Only active cells are considered in predictions

Frequency band and channel number

Physical Cell ID

PSS/SSS ID automatically computed

Powers and energy offsets

Computed from RS EPRE*

Min. RSRP

Used as a cell coverage limit

Load conditions

DL traffic load (%)

UL noise rise due to surrounding mobiles (dB)


*RS EPRE: Reference Signal Energy Per Resource Element

Cell Parameters

Main parameters

Automatic resource allocation parameters

Allocation status

Channels

Physical Cell ID

PRACH RSI


Cell Parameters

Main parameters

Layer

Similar to HCS layers in 2G networks and layers in 3G

Used to model HetNets*

Frame configuration (optional)

See next slide

MIMO configuration

Diversity support DL/UL:

Transmit diversity

SU-MIMO

AAS: Advanced Antenna Systems

MU-MIMO

Neighbours-related parameters


*HetNets: Heterogeneous Networks

Cell Parameters

Specific frame configurations

Each cell can be assigned a specific frame configuration (optional)

PDCCH/PUCCH overheads and cyclic prefix can be set for each frame

Override values defined in global parameters

PRACH preamble format

Defines a max. distance limiting the best server coverage (see 3GPP specs.)

Specific parameters used in case of interference coordination support (ICIC)

Group 0/1/2 frequency blocks, ICIC mode, cell-edge power boost (DL)

TDD parameter: Special Subframe Configuration



What is HetNets?

HetNets, or Heterogeneous Networks, are comprised of traditional large macrocells and smaller cells like:

Microcells (< 5W)

Picocells (< 1W)

Femtocells (~ 200mW)

HetNets provide two basic benefits to operators:

Increase capacity in hotspots as traffic is not uniformly distributed

Improve coverage in places where macro coverage is not adequate



Heterogeneous network deployment

Atoll LTE fully supports multi-layer networks

Different layers with different priorities

Taken into account to determine the best serving cell ( they are not used in simulation)

The definition of layers can be based on the operating frequencies

Each cell has to be mapped to a layer

You can also assign supported layers to different services and terminals

Layers management

You can define network layers with corresponding:

Priorities

Supported mobile speeds



Layers management

Principle of the cell selection margins

Due to the wide difference of power levels between macro and pico/femtocells, most of the UEs will get associated to the macrocells resulting in a load imbalance throughout the network

To counterbalance this effect, and thus enhance the system performance, an offset is to be added to the actual RSRP value from the pico/femtocells (range expansion) during the cell selection process

Cell range expansion concept modelled by cell selection margins in Atoll


Area where the picocell is received with a higher power than the macrocell

The Handover Margin is used for selecting the best server and for avoiding the ping-pong effect* between cells.


Can be defined in the transmitter properties dialogue

Cell Layer parameter [Cells tab]


The CIO is used in order to rank the potential servers for best serving cell selection in connected mode

Cell Selection Threshold (CST) is used to adjust the Min RSRP threshold of cells belonging to different priority layers

Handover ping-pong*: base stations bounce the link with the mobile back and forth between cells.


Compatibility between services, terminals and network layers

Managed in the services and terminals properties


Best Server Identification

Best Server determination

(1) Filter the potentials serving cells based on

Cell, service and terminal compatibility with the selected layer

Layers maximum speed Mobility Types speed (Layers table and Mobility Type table)

UECell distance PRACH maximum cell range

RSRP > min RSRP (Cell table)

(2) Identify the initial serving cell

On each pixel, Atoll selects the serving cells corresponding to the highest priority layer

Atoll verifies if these servers respect a RSRP level > min RSRP + Cell Selection threshold

If they do, the server with the maximum RSRP level will be considered as initial serving cell

(3) Atoll calculates the best server criterion (BSc) for the initial serving cell and the other potential serving cells

Initial serving cell: BSc = RSRP + Handover Margin + CIO

Other serving cells: BSc = RSRP + CIO

(4) The server with the highest best server criterion (BSc) will be considered as best server (for all potential serving cells from all layers)



Use case : 1 Macro site 800 MHz + 2 Micro sites 1800 MHz + 6 Small Cells 2600 MHz


Cell Table

Mobility Types

Cell TypeRSRP Level

(dBm)Distance (m) Layer

Layer Max

Speed

Small 3 -114 88 Small Cell 2600 50

Macro 2 -106 1860 Macro 800 120

Micro 2_3 -108 744 Micro 1800 50

Micro 2_2 -110 744 Micro 1800 50

Small 4 -118,5 118 Small Cell 2600 50

Micro 2_1 -122 744 Micro 1800 50


Step 1 : Atoll filters potential serving cells

Use case inputs:

In Cells Table, minimum RSRP = -120 dBm

For Pedestrian Mobility Type, average speed 3 km/h

High Speed Internet Service: All layers allowed

MIMO Terminal: All layers allowed

Default configuration for frame configuration => PRACH format 0 (max distance 14521 m)


Potential serving cells respecting conditions

Cell TypeRSRP Level

(dBm)

Cell Selection

Threshold

Minimum

level targetedLayer

Layer Priority

(Lowest 0)

Small 3 -114 2 -118 Small Cell 2600 2

Macro 2 -106 0 -120 Macro 800 0

Micro 2_3 -108 0 -120 Micro 1800 1

Micro 2_2 -110 0 -120 Micro 1800 1

Small 4 -118,5 2 -118 Small Cell 2600 2

Step 2 : Identify the initial serving cell

Atoll selects the serving cells corresponding to the highest priority layer from the potential serving cells and verifies if these servers respect a RSRP level > min RSRP + Cell Selection threshold

If the servers respect this minimum condition, Atoll selects the server with the highest RSRP level and consider it as the initial serving cell

The Small Cell 3 is the initial serving cell in this use case



Highest priority layer selection

Cell TypeRSRP Level

(dBm)

Handover

Margin (dB)

Cell Individual

offset (dB)

BSc

(dB)

Small 3 -114 4 4 -106

Macro 2 -106 0 0 -106

Micro 2_3 -108 2 1 -107

Micro 2_2 -110 2 1 -109

Small 4 -118,5 4 4 -114,5

Step 3 : Atoll calculates the best server criterion (BSC) for the initial serving cell and the other potential serving cells

Best serving cell candidate: BSC = RSRP + Handover Margin + CIO

Other serving cells: BSC = RSRP + CIO



Handover Margin applied for the cell candidate only

CIO applied for all serving cells.

Step 4: Atoll considers the cell with the highest BSc as the best server: Small Cell 3



The serving cell with the highest RSRP level is not necessarily the best server. The selection is based on the BSc calculation.

MACRO 900

MICRO 2100

Small cell range expansion: The Small cell maintains connection with the UE outside its best server area. The expansion is impacted by the CIO and the Handover Margin.

MACRO 900

Range expansion analysis: LTE specific predictions are impacted by the new best server algorithm

Impact on a Effective Signal Analysis displaying the RSRP level per best server area

The handover margin and the CIO impact the RSRP level shown per pixel. The best server area is changed so the RSRP level is automatically changed



RSRP level without considering layers RSRP level considering layers


Best server selection new algorithm


Potential serving cells based on

Service/Terminal compatibility

Minimum RSRP level Mobility type vs layer max speed

PRACH max cell range

Rank the different servers

based on

Layers priority Maximum level considering CST*

Atoll analyses the Cell

Individual Offset and Handover

Margin

Best Server identified

CTS*: Cell Selection Threshold

Carrier Aggregation (LTE-A)

Definition

Carrier Aggregation (CA) increases the channel bandwidth by combining multiple RF carriers

Each individual RF carrier is known as a Component Carrier (CC)

All CCs belong to the same eNodeB

5 CCs may be aggregated to reach a maximum of 100 MHz

However, initial LTE-A deployments will likely be limited to 2 CCs

Carrier Aggregation is applicable to both DL and UL, and both FDD and TDD

3 general types of Carrier Aggregation scenario have been defined by 3GPP

Intra-band contiguous

Intra-band non-contiguous

Inter-band



Carrier Aggregation categorises cells as:

Primary Cell

The cell upon which the UE performs initial connection establishment

Each connection has a single primary cell

The primary cell can be changed during the handover procedure

Used to generate inputs during security procedures

Used to define NAS mobility information (e.g. Tracking Area Identity)

Secondary Cell

A cell which has been configured to provide additional radio resources after connection establishment

Each connection can have multiple secondary cells


Serving Cell

Both primary and secondary cells are categorised as serving cells

There is one HARQ entity per serving cell at the UE

The different serving cells may have different coverage


Primary and Secondary cells are modelled in Atoll via the parameter Cell Type

Defines whether the cell supports LTE (3GPP Rel-8/9) and/or LTEA (3GPP Rel-10 and later)

A cell can be configured to be a LTE cell, a LTEA P-Cell (Primary Cell), and a LTEA S-Cell (Secondary Cell)

If the cell type is left empty, Atoll considers it as LTEonly

Both LTE and LTEA users can connect to LTEonly cells without the possibility to perform Carrier Aggregation

Cells that only support LTEA, and not LTE, can only serve LTEA users

The process of only allowing LTEA users to connect to a cell and excluding all LTE users is called Cell Barring



UE Categories in Atoll


Specific UE Categories

LTE-A to LTE Downgrade Category: Used to define the UE category to consider when a LTE-A mobile is connected to a LTE Rel-8/9 cell


LTE-A terminals in Atoll

Carrier Aggregation support is defined at the terminal level

You have to define the maximum number of Secondary Cells supported in DL and UL

The number of UL Secondary Cells must be less than or equal to the number of DL Secondary Cells

Setting the maximum number of Secondary Cells to 0 means that the terminal does not support Carrier Aggregation



Services in Atoll

Define whether a service can manage carrier aggregation or not



Improvements in predictions for Carrier Aggregation

You can carry out coverage predictions for different serving cells

Main (P-Cell or LTE Rel-8/9 cells)

Nth S-Cell

You can also perform aggregated throughput predictions including all serving cells, or even some of them


Throughput prediction Coverage prediction


Example: Coverage by throughput

Intra-band contiguous Carrier Aggregation

Co-located cells with similar coverage

Channel width = 20 + 20 MHz

MIMO 2 X 2 (TX DIV+SU-MIMO)


With a LTE Rel-8/9 terminal With a LTE-A terminal


Improvements in the Point Analysis Tool for Carrier Aggregation


Aggregated throughput

Serving Cells (P-Cell and S-Cell)

1. LTE Concepts



4. LTE Predictions



7. MIMO Features


Training Programme

4. LTE Predictions

Introduction

Parameters used in Predictions

Prediction Settings

Fast Link Adaptation Modelling

Coverage Prediction Examples

Point Analysis Studies


Introduction


RSRP level: Receive Signal Receive Power calculated for one RE RS level: Reference Signal level calculated on the whole bandwidth

Coverage predictions

RSRQ: Reference Signal receive Quality PDSCH C/I+N: Signal-to-interference-plus-noise ratio based on the PDSCH

channel

RS C/I+N: Signal-to-interference-plus-noise ratio based on the Reference Signal channel

Quality predictions

Based on the RLC or Application layers Peak, Effective or Average throughput Carried out for one or several users

Throughput predictions

Introduction

Principle of LTE studies based on traffic

Study calculated for:

Given load conditions:

UL noise rise (dB)

DL traffic load (%)

A non-interfering user with:

A service

VoIP,

Web browsing,

FTP download...

A mobility

Fixed,

Pedestrian,

50 Km/h...

A terminal type

Smartphone,

Rooftop terminal...


LTE prediction

UL noise rise

DL traffic load

Service Mobility

Terminal

Load Conditions

Load conditions, defined in the cells properties

Traffic load (DL) (%)

UL noise rise (dB)


Values taken into consideration in predictions for each cell

Slide 61

Service Properties

Service: parameters used in predictions

Highest/lowest bearers in UL and DL

Body loss

Application throughput parameters


Mobility Properties

Mobility: parameters used in predictions

Mapping between mobility and thresholds in bearer and quality indicator determination (as radio conditions depend on user speed)


Reception equipment properties

Mapping

Terminal Properties

Terminal: parameters used in predictions

Min/max terminal power

Gain and losses

Noise figure

Antenna settings (incl. MIMO support)

Carrier aggregation settings


Number of antenna ports in UL and DL in case of MIMO support

Min/max terminal power + noise figure + losses

Support of MIMO

Carrier aggregation parameters

Fast Link Adaptation Modelling

Atoll determines, on each pixel, the highest bearer that each user can obtain

After the layer determination, connection to the best server in terms of RS level or RSRP

Bearer chosen according to the radio conditions (PDSCH and PUSCH CINR levels)

Process: prediction done via look-up tables


RS level (C) or RSRP evaluation

Best server area determination

(limited by min. RSRP)

Radio conditions estimation

(PDSCH and PUSCH CINR calculation)

Bearer selection

Throughput & quality indicator predictions (BER

and BLER)

Interference Estimation

Atoll calculates PDSCH and PUSCH CINR according to:

The victim traffic (PUSCH or PDSCH) power [C]

The sum of interfering signals [I], affected by:

The interfering signals EIRP (power + gains - losses) weighted by traffic loads (in DL)

The path loss from the interferers to the victim

The shadowing effect and the indoor losses (optional)

The interference reduction factor applied to interfering base stations transmitting on adjacent channels (adjacent channel suppression factor)

The interference reduction due to static ICIC (optional)


Prediction Examples (General Studies)


Coverage by transmitter

(based on RSRP levels)

Cell dominance (overlapping zones)

(based on RSRP levels)

Slide 67

Prediction Examples (Dedicated Studies)


Coverage by RSRP level

Coverage by RSRP level

(with power boost)

Slide 68

Application Channel Throughput (UL)

Prediction Examples (Dedicated Studies)


Coverage by PUSCH CINR

Slide 69

Point Analysis Tool: Reception

Radio reception diagnosis at a given point


Choice of UL/DL load conditions: if (cells table) is selected analysis based on DL load and UL

noise rise from cells table

Definition of the user (layer or channel, terminal, service,

mobility) Cell bar graphs (best server on top)

Analysis details on reference signals, PDSCH and PUSCH

Reference signals,

PDSCH and PUSCH

availability (or not)

Selection of the value to be displayed (RS, SS, PDSCH, RSRP)

Slide 70

Point Analysis Tool: Interference

Radio interference diagnosis at a given point


Choice of UL/DL load conditions: if (cells table) is selected analysis based on DL load and UL

noise rise from cells table

Definition of the user (layer or channel, terminal, service,

mobility)

Selection of the value to be displayed (RS, SS, PDSCH, RSRP)

Serving cell (C)

Total level of interference

(I + N)

List of interfering cells

Slide 71

1. LTE Concepts



4. LTE Predictions



7. MIMO Features


Training Programme

5. Neighbour Allocation

Detailed information about neighbours allocation is available in Atoll_3.3.0_Neighbours.pdf


1. LTE Concepts



4. LTE Predictions



7. MIMO Features


Training Programme


Automatic Physical Cell ID planning

AFP overview

Automatic resource allocation process

Interference matrix calculation

Physical Cell ID overview

PCI allocation process

Running the automatic resource allocation

PCI allocation examples

Automatic frequency planning

Running the automatic resource allocation

Frequency allocation examples

Automatic PRACH Root Sequences

PRACH channel

PRACH RSI Planning Theory

Automatic PRACH RSI Planning


AFP Overview (1/2)

Prerequisite: AFP license

Goal: Optimize resource allocation (channels, PCI or PRACH RSIs) following the user-defined constraints

To minimize interference (channels)

To avoid collisions (PCI)

To avoid PRACH root sequence index collisions (PRACH RSIs)

Tool based on an iterative cost-based algorithm

The algorithm starts with the current frequency plan (used as initial state)

Different frequency plans are then evaluated and a cost is calculated for each of them

The best frequency allocation plan is the one with the lowest global cost


AFP Overview (2/2)

The cost is calculated thanks to:

Interference matrices

Probabilities of interference in co- and adjacent channel cases

A probability is calculated for each case and for each interfered-interfering cell pair

Distance relation

Avoid frequency reuse between cells for which the inter-site distance is lower than a min. reuse distance

Taking into account distance and cells azimuth

Neighbours

Taking into account neighbours importance (can be calculated by Atoll)


Automatic Resource Allocation Process


Define radio parameters at cells level

Frequency band allocation

Allocation status: not allocated or locked

Minimum reuse distance (optional)

Import / calculate a neighbour plan

Import / calculate an interference matrix

Run the automatic resource allocation tool

Commit and analyse results

Interference Matrix Calculation (1/2)

Interference matrix definition

For each cell pair, interference probability for co and adjacent channel cases

Probabilities of interference are stated as the ratio between:

The interfered area within the best server area of the victim

Best server area of the victim

Co-channel interference occurs when:


TX_A Victim Transmitter

Serving Area

TX_B Interfering Transmitter

Area where TX_B is interfering TX_A

Interference probability = 50%

In other words, 50% of TX_As serving area is interfered by TX_B

Signal Reference

N

CMin

NMI

C

Q

Slide 79

Interference Matrix Calculation (2/2)


Physical Cell ID Overview

Physical Cell ID definition

Cell search and identification is based on Physical Cell IDs

Optimised allocation needed to avoid unnecessary problems

in cell recognition and selection

504 Physical Cell IDs defined by 3GPP

Physical Cell ID grouped into:

168 unique Cell ID groups (SSS IDs in Atoll, from 0 to 167)

Each group containing 3 unique identities (PSS IDs in Atoll, from 0 to 2)

Each cells reference signal transmits a pseudo random sequence corresponding to the Physical Cell ID of the cell

When Physical Cell ID + pseudo-random sequence is known, cell is recognized by mobile based on the received reference signal

Channel estimation performed on reference signals


(Cell search procedure)

Physical Cell ID Allocation Process

PCI allocation to cells

Main requirement

Avoid PCI collision and confusion

Not allocate the same PCI to nearby cells

To avoid problems in cell search and selection

Secondary requirements

Different PSS ID at nearby cells

Avoid RS-RS collisions

Preferably the same SSS ID at co-site cells (especially in the case of 3-sector sites)

May facilitate neighbour cell identification

May help in measurements and handover procedures


PCI A PCI A

PCI collision

PCI A PCI B

PCI B

PCI confusion

Slide 82

Running the Automatic Resource Allocation (1/6)





Allocation constraints

Possibility to allocate channels or Physical Cell IDs

Run the calculation

Slide 84




Possibility to allocate channels or Physical Cell IDs

Run the calculation

Slide 85



During the optimisation, you can monitor the reduction of the total cost



You can compare the distribution histograms of the initial and current allocation plans



Once Atoll has finished allocating Physical Cell IDs, the proposed allocation plan is available on the Results tab

The proposed PCI plan can be assigned automatically to the cells of the network if you click Commit


Physical Cell ID Allocation Results (1/2)

Automatic Physical Cell ID allocation in Atoll (example)

Same PCI all over - RS coverage C/(I+N) with DL traffic load = 0%


Physical Cell ID Allocation Results (2/2)

Automatic Physical Cell ID allocation in Atoll (example)

Automatic PCI allocation with AFP - RS coverage C/(I+N) with DL traffic load = 0%


Automatic Frequency Planning (1/2)

Philosophy of the channels automatic allocation is really similar to PCI allocation

Automatic channels allocation prerequisites

Define radio parameters at cells level

Frequency band

Channel allocation status

Minimum reuse distance

Neighbour plan

Interference matrix (as explained previously)


Automatic Frequency Planning (2/2)

Philosophy of the channels automatic allocation is really similar to PCI allocation


Frequency Allocation Examples (1/2)

Basic frequency allocation (Single Frequency Network)

Same channel all over (15 MHz) - RS coverage C/(I+N):


Frequency Allocation Examples (2/2)

Optimised frequency allocation with AFP

3 channels (5 MHz) - RS coverage C/(I+N):


Find on Map Tool Overview

You can visualise channels and PSS ID reuse on the map

Possibility to find cells which are assigned a given:

Frequency band + channel

Physical Cell ID

PSS ID

SSS ID

Way to use this tool

Create and calculate a coverage by transmitter with a colour display by transmitter

Open the Find on map tool available in the tools menu

or use [Ctrl+F],

or directly in the toolbar


Channel Search

Channel reuse on the map


Colours given to transmitters: Red: co-channel transmitters Yellow: multi-adjacent channel (-1 and +1) transmitters Green: adjacent channel (-1) transmitters Blue: adjacent channel (+1) transmitters Grey thin line: other transmitters

Slide 96

Physical Cell ID Search

Physical Cell ID, PSS ID or SSS ID reuse on the map


Colours given to transmitters: Red or grey thin line: if the transmitters carries or not the specified resource value (Physical Cell ID, PSS ID or SSS ID)

You can check if your constraints are satisfied by the current allocation by performing an audit

Respect of a minimum reuse distance

Respect of neighbourhood constraints (two neighbour cells must have a different PCI)

Respect of PSS/SSS ID allocation strategy

PCI Allocation Audit (1/2)


PCI Allocation Audit (2/2)

Audit results


The exclamation mark icon ( ) means that the collision may or may not be a problem depending on your network design rules and selected strategies. On the other hand, the cross icon ( ) implies an error.

Automatic PRACH RSI

PRACH channel


Automatic PRACH RSI Planning


PRACH Channel

The Physical Random Access CHannel (PRACH) is used to transmit the random access preamble used to initiate the random access procedure. This channel allows UEs to achieve uplink time synchronisation

PRACH resources are multiplexed with PUSCH and PUCCH


CYCLIC

PREFIXSEQUENCE

GUARD

TIME839 subcarriers for preamble format 0 to 3 => 6 RB

139 subcarriers for preamble format 4

Duration depends on the preamble format

1.25 kHz wide Subcarriers for formats 0 to 3 7.5 KHz wide Subcarriers for format 4

Contention-free random Access Procedure

PRACH Channel

Different sections of the network can be planned with different preamble formats if the cell range varies from one area to another

The format 0 is the default format as it generates a small overhead and allows reaching a maximum cell range of 15 km which the most common situation


Preamble

Format

Duplex

Mode

Cyclic Prefix

Duration

Sequence

Duration

Guard

Time

Total

Length

Typical Max.

Cell Range

0 FDD/TDD 103,13 us 800 us 96,88 us 1 ms 14,5 km




4 TDD 14,58 us 133 us 9,38 us 0,16 ms 1,4 km


Purpose: Determine different preamble sequences to allow multiple UE using the same frequency and time domain resources to simultaneously connect to an eNB. Each sequence is generated by cyclic shifting one or several root sequence index (RSI).

Preamble sequences are CAZAC* codes generated using the Zadoff-Chu method

Each cell has 64 preamble sequences (16 were available for UMTS/HSPA)

838 RSI are available for FDD (format 0 to 3) and 138 for TDD (format 4).

Depending on the PRACH format (or cell size), a different quantity of RSI is required per cell.


* CAZAC: Constant Amplitude Zero Autocorrelation

15 km

RSI 10-19 4 km

RSI 0-2

Suburban-Rural Cell 10 RSI required per cell

Urban Cell 3 RSI required per cell


The root sequence index values allocated to each cell should ensure that neighbouring cells have different sets of root sequences

A maximum RSI re-use can be implemented when a minimum number of RSI is used

For the urban case, 3 RSI are necessary per cell. 838 different RSI are available, so 838/3 279 cells can be allocated before reuse

For the rural case, 10 RSI are used per cell 838/10 83 cells can be allocated before reuse


Suburban-Rural Cell 10 RSI required per cell

Urban Cell 3 RSI required per cell


Atoll will allow the user to directly enter the number of required root sequence per cell.

This approach provides the most flexibility in case of different equipment and propagation environments imply additional delays and margins which impact the calculation of the quantity of required root sequence per cell.

The mapping tables show values calculated for ideal conditions, i.e., no delay spread and perfect equipment. There are shown for information only .

3GPP parameters used for the PRACH RSI allocation are described in the following table


Parameter Range Description

PRACH Configuration Index 0 to 63 Determines the preamble format, version and density

Zero Correlation Zone 0 to 15

Determines the size of the cyclic shift and the number

of preamble sequence that can be generated from each

root sequence

High Speed Flag True/False Reduce Doppler effect at very high speed (> 200 km/h)

Root Sequence Index 0 to 837Preamble sequence generated form root sequence

index

PRACH Frequency Offset 0 to 94Determines the PRACH preambles position in the

frequency domain

Automatic PRACH RSI Planning (2/8)






Resource selection

Run the calculation

Slide 107

Initial cost calculation before planning

Cell parameters




Specify PRACH RSI resources to be used for the allocation

Slide 108



Once Atoll has finished allocating PRACH RSIs, the proposed allocation plan is available on the Results tab

The proposed PRACH RSI plan can be assigned automatically to the cells of the network if you click Commit



A quantity of 10 PRACH RSIs has been automatically allocated per cell because of the cell table configuration



The LTE prediction, Cell Identifier collision zones, allows verifying if any collisions occur between cells with one or several identical PRACH RSIs


You can check if your constraints are satisfied by the current allocation by performing an audit

Respect of a minimum reuse distance

Respect of neighbourhood constraints (two neighbour cells must have different PRACH RSIs)

Interference matrix consideration



1. LTE Concepts



4. LTE Predictions



7. MIMO Features


Training Programme

8. MIMO Features

Introduction

MIMO Techniques Overview

MIMO Settings in Atoll

Dynamic MIMO Switching

Diversity and Throughput Gains

Calculation Details

Use Case: 4x2 MIMO (TX DIV+SU-MIMO)


Introduction (1/2)

Shannons formula

Theoretical limit to transmit without error: = . 2(1 + SNR) , (bits/s)

How to increase the channel capacity ?

Increase the bandwidth (W )

Improve the Signal to Noise Ratio (SNR )

Limitation of SISO* systems to reach very high data rates

Why MIMO ?

The usage of multiple antennas improves dramatically the channel capacity without additional bandwidth or transmit power

Expected benefits with MIMO

Higher throughput

Better coverage


*SISO: Single Input Single Output

Introduction (2/2)

General concept of MIMO

Multiple Input Multiple Output (MIMO) configurations benefit from multiple antenna elements at the transmitter and multiple antenna elements at the receiver

Terminology

Similar terminology is used for Single Input Multiple Output (SIMO), Multiple Input Single Output (MISO), and Single Input Single Output (SISO)


Propagation

channel

4x2 MIMO

Propagation

channel

1x4 SIMO

Propagation

channel

4x1 MISO

Propagation

channel

SISO

MIMO Techniques Overview

Four different MIMO techniques can be listed


Transmit diversity

Aims to improve the signal quality by sending several times the same data stream

Usually used in areas with bad CINR conditions

Single-User MIMO (or SU-MIMO, also referred to as Spatial Multiplexing)

Aims to improve the signal throughput by transmitting simultaneously (i.e. using the same set of time/frequency resources) multiple data streams to a single user

Usually used in areas with good CINR conditions

Beamforming

Aims to improve both signal quality and throughput by focusing the signal energy towards the receiver

Multi-User MIMO (or MU-MIMO)

Aims to improve the system capacity by sending simultaneously different data streams to different users

Transmitters Settings

You have to set the appropriate number of antenna ports at the Transmitters level


In this example, 4 ports are defined for the transmission (used for DL calculations), and 2 ports for the reception (used for UL calculations)

Propagation

channel

4x? MIMO (DL)

?

Propagation

channel

?x2 MIMO (UL)

?

Depends on the number of reception antenna ports defined in the terminal properties (see slide 49)

Depends on the number of transmission antenna ports defined in the terminal properties (see slide 49)

Cells Settings

MIMO techniques support

You can define the MIMO techniques supported by your equipment in UL/DL in the Cells properties

AAS = Active Array System (beamforming)

For more information see the training course LTE Features Advanced

MU-MIMO

For more information see the training course LTE Features Advanced


Tx/Rx diversity

UL/DL

SU-MIMO

UL/DL

AAS

DL only

MU-MIMO

UL/DL

Terminal Settings

You have to configure a terminal that supports MIMO


MIMO support

Number of antenna ports in UL and DL in case of MIMO support (1Tx/2Rx is the most common configuration at the moment)

LTE equipment defining SU-MIMO and diversity gains

Definition

Atoll can dynamically switch between different MIMO techniques depending on the radio condition

Different option can be implemented:

TX DIV SU-MIMO, TX DIV MU-MIMO, TX DIV MU-MIMO SU-MIMO

In this example, Atoll can automatically switch from SU-MIMO to Tx/Rx diversity as the radio conditions deteriorate

Advantages

Improves the throughput for users situated near the transmitter

Increases the signal quality for cell edge users

Dynamic MIMO mode (1/3)


Good radio conditions -> Use of SU-MIMO -> Better throughput

Bad radio conditions -> Use of Tx/Rx diversity -> Better CINR

Transition area between SU-MIMO and Tx/Rx diversity -> Determined by the SU-MIMO threshold (see next slide)

The SU-MIMO threshold is the parameter used to switch from SU-MIMO to Tx/Rx diversity

It can be defined in the reception equipment properties

Default Cell Equipment (for UL calculations)

Default UE Equipment (for DL calculations)

It is expressed in dB and refers to the Reference Signal or the PDSCH/PUSCH quality

Dynamic MIMO mode (2/3)


The SU-MIMO threshold depends on the user mobility

You can choose the criterion the SU-MIMO threshold will be based upon in the LTE global settings

Reference Signal C/N or C/(I+N)

PDSCH or PUSCH C/(I+N)

Dynamic MIMO mode(3/3)


Diversity and/or throughput gains can be applied when using certain MIMO techniques

They depend on the MIMO configuration used (2x1 MIMO, 2x2 MIMO, 4x4 MIMO)

Besides PDSCH and PUSCH, PBCH and PDCCH can also benefit from diversity gains

All values set here should be in line with your vendor specific equipment

Diversity and Throughput Gains (1/2)


Diversity and Throughput Gains (2/2)

Additional diversity and throughput gains are defined in the clutter classes properties

Diversity and throughput gains can be tuned according to the environment


Calculation Details (1/2)

CINR improvement with the transmit diversity technique

Lets consider for instance the CINRPDSCH


CINRPDSCH (With MIMO) = CINRPDSCH (Without MIMO) + Diversity Gain + Additional Diversity Gain (DL)

Calculation Details (2/2)

Throughput improvement with the SU-MIMO technique

Lets consider for instance the DL peak RLC channel throughput


Peak Th. (With MIMO) = Peak Th. (Without MIMO) x [ 1 + (Max MIMO Gain 1) x LTE SU-MIMO Gain Factor ]

Use Case: 4x2 MIMO DL (TX DIV+SU-MIMO) (1/5)

Atoll configuration

4 transmission antenna ports

Transmitters properties

2 reception antenna ports

Terminal properties

Diversity support (DL)

TX DIV + SU-MIMO


Note: Traffic load (DL) = 75%


Peak RLC Channel Throughput Analysis (DL)

Conditions:

Traffic load (DL) = 75%

Channel width = 10 MHz

Normal CP, PDCCH overhead = 2

SU-MIMO threshold = 12 dB (RS CINR)

Service = High Speed Internet

Mobility = Pedestrian


Without MIMO

4x2 MIMO (TX DIV+SU-MIMO)

SU-MIMO threshold

Tx/Rx diversity

SU-MIMO


Peak RLC Channel Throughput Analysis (DL) near the transmitter

Results based on pixels where the SU-MIMO technique is used (RS CINR > 12 dB)


0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70

Peak RLC Throughput (Mbps)

Without MIMO

AMS 4x2

* AMS: Adaptive MIMO Switching between TX Div and SU-MIMO


Quality analysis - PDSCH C/(I+N)

Conditions:

Traffic load (DL) = 75%

Channel width = 10 MHz

Normal CP, PDCCH overhead = 2

SU-MIMO threshold = 12 dB (RS CINR)

Service = High Speed Internet

Mobility = Pedestrian


Without MIMO

4x2 MIMO (TX DIV+SU-MIMO)

SU-MIMO threshold

No service

Tx/Rx diversity

SU-MIMO


Quality analysis - PDSCH C/(I+N)

The overall quality (near transmitter and at cell edge) is considered on the chart below


0

10

20

30

40

50

60

70

80

90

100

-20 -15 -10 -5 0 5 10 15 20 25 30

PDSCH C/(I+N) (dB)

Without MIMO

AMS 4x2

* AMS: Adaptive MIMO Switching between TX Div and SU-MIMO


Appendix

Slide 133

LTE throughput formulas

Downlink Peak RLC channel Throughput

=

Number of Ressource Elements available for PDSCH

Bearer Efficiency : Number of bits per symbol * Coding rate

Frame duration : 10 ms

Downlink Effective RLC channel throughput

= ( )

BLER: Downlink block error rate read from the graphs available in LTE Network Settings / Reception Equipment



Downlink Application channel throughput

=

Throughput scaling factor defined in the properties of the service used by the pixel (Traffic parameters / Services)

Throughput offset defined in the properties of the service used by the pixel (Traffic parameters / Services)

Downlink peak RLC cell capacity

= . .

T.L.: Maximum Downlink Traffic Load

Downlink effective RLC cell capacity

= ( )

BLER: Downlink block error rate read from the graphs available in LTE Network Settings / Reception Equipment

Peak Cell Capacity: Downlink Peak RLC Cell capacity (kbps)



Downlink Application cell capacity

() = ( )/

Throughput scaling factor defined in the properties of the service used by the pixel (Traffic parameters / Services)

Throughput offset defined in the properties of the service used by the pixel (Traffic parameters / Services)

Downlink peak RLC throughput per user

=

N DL users: Number of users connected to the cell in downlink

Downlink effective RLC throughput per user

=

N DL users: Number of users connected to the cell in downlink



Downlink application throughput per user

=

NDL users: Number of users connected to the cell in downlink


RSRQ formula

RSRQ is the ratio over the entire channel bandwidth of the wanted RS signal / All signal

=

RSRP: Received Signal Received Power: Received Power at the UE per Reference signal channel resource element from its serving cell

RSSI: Received Signal Strength Indicator: Total power received at the UE from its serving and adjacent cells

NRB : Number of resource blocks over which the RSSI is measured



Thank you

Slide 139

Atoll_3.3.0_LTE

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