aircominternational-casestudy-ltesmallcellplanningusingasset

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Case Study

LTE Small Cell planning using ASSET

AIRCOM International Cassini Court, Randalls Way,

Leatherhead, KT22 7TW United Kingdom

www.aircominternational.com

http://www.aircominternational.com/

LTE Small Cell planning using ASSET © AIRCOM International, 2012 Page 2 of 20

Table of Contents

1 Executive Summary .................................................................................................... 3 2 Introduction ............................................................................................................... 4 3 Configuration ............................................................................................................. 4

3.1 Analysis Area ..................................................................................................... 4 3.2 Propagation Modelling ........................................................................................ 4 3.3 Macrocell Layer .................................................................................................. 5 3.4 Small Cell Layer .................................................................................................. 5 3.5 Traffic Model ...................................................................................................... 5 3.6 Traffic Raster ..................................................................................................... 5

4 Coverage Analysis ...................................................................................................... 6 4.1 Coverage with Building Vectors displayed ............................................................ 7

4.1.1 LTE Macrocell Best RSRP ................................................................................. 7 4.1.2 LTE Small Cell Best RSRP ................................................................................ 7 4.1.3 Combined LTE Macrocell & Small Cell Best RSRP............................................... 8

4.2 Coverage Statistics ............................................................................................. 8 5 Interference/Quality Analysis ...................................................................................... 9

5.1 Interference/Quality with Building Vectors displayed ............................................. 9 5.1.1 LTE Macrocell Best RSRQ ................................................................................ 9 5.1.2 LTE Small Cell Best RSRQ .............................................................................. 10 5.1.3 Combined LTE Macrocell & Small Cell Best RSRQ (Single Carrier) ..................... 10 5.1.4 Combined LTE Macrocell & Small Cell Best RSRQ (Two Carriers) ...................... 11

5.2 Interference/Quality Statistics ........................................................................... 11 6 Failure rate and failure reasons analysis ..................................................................... 12

6.1 Failure Rate Arrays ........................................................................................... 12 6.1.1 LTE Macrocell Failure Rate ............................................................................ 12 6.1.2 LTE Small Cell Failure Rate ............................................................................ 13 6.1.3 Combined LTE Macrocell & Small Cell Failure Rate (Single Carrier) ................... 13

6.2 Failure Reason Arrays ....................................................................................... 14 6.2.1 LTE Macrocell Failure Reason ........................................................................ 14 6.2.2 LTE Small Cell Failure Reason ........................................................................ 15 6.2.3 Combined LTE Macrocell & Small Cell Failure Reason (Single Carrier) ............... 15

6.3 Simulation Statistics.......................................................................................... 16 7 Conclusion ............................................................................................................... 17 8 Glossary .................................................................................................................. 18 9 Appendix A - About the Products and modules used in this application note ................. 19

9.1 ASSET 8.0 ........................................................................................................ 19 9.2 Myriad ............................................................................................................. 19


1 Executive Summary

With wireless data already predicted to exceed wired data in the next few years and network capacity demands to increase 20-40 fold over the next 5 years, mobile operators are under

pressure to dramatically increase their network capacity and maintain data throughput rates, in a cost effective manner. Embracing a Small Cell strategy seems to be the most common

approach to achieve this across the World’s operators.

Small Cell technology (which includes femto, pico and micro cells) is currently in use by 67%

of operators according to the Small Cell Forum and usage will increase from 4.3 million small cells to 36.8 million by 2016. Operator needs a planning strategy to ensure capacity issues

are addressed and throughput rates are maintained for continued positive customer experience.

Small cells can solve the data bandwidth issues and provide improved indoor coverage but careful planning is critical to ensure they do not introduce additional network interference and

degrade overall network performance.

A case study will be presented on how LTE Small Cells can be planned with ASSET 8.0 using

a high-traffic, high-density area of central London, in the United Kingdom, which contains both Small Cells and Macro cells.

We will demonstrate how to setup a Small Cell LTE layer on top of an LTE Macrocell layer in

AIRCOM’s ASSET Radio Network Planning tool and how the Coverage, number of served users, throughput and quality improve significantly by doing so. It will also show that the

introduction of Small Cells provides the biggest benefit in terms of improving the number of

successfully served terminals and that having separate carriers for the macro and small cell layers helps in reducing failures further particularly those due to capacity problems.


2 Introduction

This document demonstrates how LTE Small Cells can be planned with ASSET v8.0. For this case study we are using a high-traffic, high-density area of central London, in the United

Kingdom, which contains both Small Cells and Macro cells. The Macrocell sites locations are real ones obtained from the UK’s regulator’s published data.

We will show the configuration in ASSET, the Coverage (RSRP) and Interference (RSRQ) analysis, as well as the number of Served Terminals Macrocell layer alone, for the Small Cells

alone and for the combined Macro + Small cell layers using a single carrier and then using separate carriers. Details of the configuration and of the reports run can be obtained by

contacting your local AIRCOM representative.

We will demonstrate how to setup a Small Cell LTE layer on top of an LTE Macrocell layer in

AIRCOM’s ASSET Radio Network Planning tool and how the Coverage, number of served users, throughput and quality improve significantly by doing so. It will also show that the

introduction of Small Cells provides the biggest benefit in terms of improving the number of successfully served terminals, but that having separate carriers for the macro and small cell

layers helps in reducing failures further particularly those due to capacity problems.

3 Configuration

3.1 Analysis Area

The Analysis Area covers a dense urban area of central London that includes Covent Garden and Holborn and is bounded by Soho, Leicester Square and Tottenham Court Road.

3.2 Propagation Modelling

A MYRIAD propagation model was configured using Height data to create Facets, Clutter data to create Morphologies and Building Vectors to create Graphs along the streets. For the

configuration of the Myriad model, please contact your AIRCOM local representative.


Predictions for both Macrocells and Small Cells were calculated using the MYRIAD Model with

a Prediction Resolution of 5m (even though the highest Map Data resolution was 50m) and

Prediction Radius of 3km.

3.3 Macrocell Layer

The LTE Macrocells of UK Operators, for the central London area, have been created and

used to generate Macrocell Coverage. They have been configured to use a single 10MHz

Carrier with a Max TX Power of 10W (40dBm).

From the report below containing the antenna configuration of the Macrocells in and surrounding the Use Case Area it can be seen that they are all three sector sites with antenna

heights ranging from 19-100m with an average height of 32.5m, total downtilts range from 3-14o with an average downtilt of 7.2 o.

3.4 Small Cell Layer

Twenty LTE Small Cells were manually added using a Template in an area of poor Macrocell

Coverage, as per the initial results from analysing the Macrocell layer. The Small Cell

Template was designed to model a deployment utilizing street furniture i.e. lamp posts, traffic lights, etc. so the configuration included the following:

Three Sector Sites with Antenna Azimuths of 0, 120 & 240o and Azimuths separation

fixed at 120o

Antenna Height of 4m

Fixed Total Downtilt of 0o

Single 10MHz Carrier

Max TX Power of 1W (30dBm)

The majority of Small Cell Sites have been positioned on street corners or junctions, although

there are a few in squares. If necessary the antenna azimuths have been adjusted from the

default (0, 120 & 240o) but the azimuth separation has been fixed at 120o to model the use of a fixed antenna housing.

3.5 Traffic Model

An LTE real time data terminal was used for the simulation. This used the default Streaming-

QCI-4 Service available in ASSET v8.0 that is configured to provide an UL GBR of 500kbps and DL GBR of 1000kbps. The terminal’s RF Parameters were configured as follows:

Parameter Value Parameter Value Max Tx Power (dBm) 23 Antenna gain (dBi) 0

Tx Dynamic range (dB) 70 Horiz. Beamwidth (deg) 360

Req. RSRP (dBm) -122 Body Loss (dB) 1

Req. RSRQ (dBm) -18 Noise figure (dB) 7

Req. BCH/SCH SINR (dB) -15 Background Noise (dBm/Hz) -167

RC combining gain (dB) 0

3.6 Traffic Raster

A traffic raster was created for the Test Area by specifying 200 Terminals to be distributed within the Small Cell Area polygon. As the majority of the area consisted of urban, dense


urban and high-rise building clutter all cutter types were equally weighted to provide a uniform traffic weighting of 1.

This produced a traffic density of 349.34 Terminals per km2. As the highest resolution of Clutter Data was 50m the Traffic Raster was created at 50m Resolution, however this traffic

was used to run the simulator at 5m resolution.

4 Coverage Analysis

The following Best RSRP Arrays are for outdoor coverage i.e. no Indoor Losses defined in the LTE Clutter Parameters have been considered, but indoor losses have been calculated for

areas inside the Building Vectors using the MYRIAD Building Calculation options. Coverage Arrays are displayed for the Macrocells only, Small Cells only and Combined Macrocells/Small

Cells both with Building Vectors to highlight outdoor street level coverage and without

Building Vectors show areas of indoor coverage.

The Best RSRP Schema is as follows:

Coverage Statistics were also calculated for the Small Cell Area polygon for Macrocells only, Small Cells only and Combined Macrocells/Small Cells.


4.1 Coverage with Building Vectors displayed

4.1.1 LTE Macrocell Best RSRP

From this picture, it can be seen that the areas in orange and red are areas with poor

coverage.

4.1.2 LTE Small Cell Best RSRP

From this picture, it can be seen that the small cells coverage is very focused on the vicinity

of the cells themselves.


4.1.3 Combined LTE Macrocell & Small Cell Best RSRP

When combining the coverage from the two layers, it can be seen that the orange and red

areas previously seen on the Macrocell-only coverage have turned to Green, or good

coverage, by adding the Small Cells layer.

4.2 Coverage Statistics

The Best RSRP Array Statistics, obtained from ASSET, can be compared in the table and

reports below.

RSRP Thresholds Macrocells Only Small Cells Only Combined Macrocell

& Small Cells

-120.00 <= x < -115.00 dBm 92.041% 96.837% 99.912%

-115.00 <= x < -110.00 dBm 84.319% 93.938% 99.420%

-110.00 <= x < -105.00 dBm 73.934% 89.699% 97.672%

-105.00 <= x < -100.00 dBm 63.434% 84.073% 94.045%

-100.00 <= x < -95.00 dBm 54.844% 76.884% 88.693%

-95.00 <= x < -90.00 dBm 44.771% 68.239% 81.392%

-90.00 <= x < -85.00 dBm 31.126% 57.043% 71.717%

-85.00 <= x < -80.00 dBm 18.779% 45.754% 58.253%

-80.00 <= x < -75.00 dBm 11.233% 36.125% 45.290%

-75.00 <= x < -70.00 dBm 6.618% 28.839% 34.873%

-70.00 <= x < -65.00 dBm 3.984% 23.431% 27.327%

-65.00 <= x < -60.00 dBm 2.055% 17.991% 20.045%

-60.00 <= x < 0.00 dBm 0.974% 9.986% 10.960%

From these statistics, it is clear that the coverage statistics are much better for the combined Macro and Small cells network than for the Macro network alone.


5 Interference/Quality Analysis

The following Best RSRQ Arrays are for outdoor interference/quality and were generated from a simulation using the Traffic Raster and snapshots.

RSRQ Arrays are displayed for the Macrocells only, Small Cells only, Combined

Macrocells/Small Cells (with a single Carrier assigned to Macro and Small Cells) and Combined

Macrocells/Small Cells (with two Carriers, one assigned to Macrocells and another assigned to Small Cells). Arrays are available with Building Vectors and without Building Vectors.

The Best RSRQ Schema is as follows:

Best RSRQ Array Statistics were also calculated for the Small Cell Area polygon for Macrocells only, Small Cells only, Combined Macrocells/Small Cells (with a single Carrier) and Combined

Macrocells/Small Cells (with two Carriers).

5.1 Interference/Quality with Building Vectors displayed

5.1.1 LTE Macrocell Best RSRQ

From this picture, it can be seen that the areas in orange represent poor quality (mostly indoors), whilst yellow is acceptable.


5.1.2 LTE Small Cell Best RSRQ

From this picture, it can be seen that the small cells quality is very good (green) on the

vicinity of the cells themselves.

5.1.3 Combined LTE Macrocell & Small Cell Best RSRQ (Single Carrier)

When combining the coverage from the two layers, it can be seen that the orange areas

previously seen on the Macrocell-only plot have turned to Green, or good quality, by adding the Small Cells layer.


5.1.4 Combined LTE Macrocell & Small Cell Best RSRQ (Two Carriers)

Having separate carriers has a positive effect on quality, although hard to visualise. A clearer

picture in terms of statistics is presented further on this document.

5.2 Interference/Quality Statistics

The Best RSRQ Array Statistics, obtained from ASSET, can be compared in the table and reports below.

RSRQ Thresholds Macrocells

Only Small Cells

Only

Combined Macrocell & Small Cells (Single

Carrier)

Combined Macrocell & Small Cells (Two

Carriers)

-30.00 <= x < -27.00 dB 100.000% 100.000% 100.000% 100.000%

-27.00 <= x < -24.00 dB 100.000% 99.995% 100.000% 100.000%

-24.00 <= x < -21.00 dB 99.981% 99.963% 100.000% 100.000%

-21.00 <= x < -18.00 dB 99.814% 99.879% 100.000% 100.000%

-18.00 <= x < -15.00 dB 99.045% 99.541% 100.000% 100.000%

-15.00 <= x < -12.00 dB 93.651% 98.646% 99.977% 100.000%

-12.00 <= x < -9.00 dB 50.851% 88.646% 94.351% 99.606%

-9.00 <= x < -6.00 dB 1.359% 38.152% 65.113% 84.579%

-6.00 <= x < -3.00 dB 0.000% 2.240% 15.769% 32.253%

-3.00 <= x < 0.00 dB 0.000% 0.000% 0.320% 1.373%

0.00 <= x < 3.00 dB 0.000% 0.000% 0.000% 0.000%

From these statistics, it is clear that the quality statistics are much better for the combined

Macro and Small cells network than for the Macro network alone.


6 Failure rate and failure reasons analysis

Monte Carlo simulations were run in ASSET to assess the Failure Rate and the Failure Reasons using the Traffic Raster and multiple simulation snapshots.

The Failure Rate and Failure Reason Arrays are displayed for the Macrocells only, Small Cells

only and Combined Macrocells/Small Cells (with a single Carrier assigned to Macro and Small

Cells). Simulation Composite Report Statistics were also calculated for Macrocells only, Small Cells only, Combined Macrocells/Small Cells (with a single Carrier) and Combined

Macrocells/Small Cells (with two Carriers).

6.1 Failure Rate Arrays

The Failure Rate Schema is as follows:

6.1.1 LTE Macrocell Failure Rate

From this picture, it can be seen that the orange and red dots signal high failure rates.


6.1.2 LTE Small Cell Failure Rate

From this picture, it can be seen that the small cells result in very low failure rates on the

vicinity of the cells themselves.

6.1.3 Combined LTE Macrocell & Small Cell Failure Rate (Single Carrier)

When combining the two layers, the orange and red dots disappear, leaving an all-green area

with very low failure rates.


6.2 Failure Reason Arrays

The Failure Reason Schema is as follows:

6.2.1 LTE Macrocell Failure Reason

From this picture, it can be seen that the non-green signal a number of failure reasons, which translate to high failure rates in the areas further away from the macro cells.


6.2.2 LTE Small Cell Failure Reason

From this picture, it can be seen that the small cells result in very low failure rates on the vicinity of the cells themselves.

6.2.3 Combined LTE Macrocell & Small Cell Failure Reason (Single Carrier)

When combining the two layers, the multi-coloured dots disappear, leaving an all-green area

with very low failure rates.


6.3 Simulation Statistics

The Simulation Composite Report Statistics, obtained from ASSET, can be compared in the

table and reports below.

Simulation Statistic Macrocells

Only Small Cells

Only

Combined Macrocell & Small Cells (Single

Carrier)

Combined Macrocell & Small Cells (Two

Carriers)

Mean Attempted 200.090 198.960 198.280 199.040

Mean Served 145.340 188.420 196.790 197.890

Mean Failed 54.750 10.540 1.490 1.150

Mean Served (%) 72.64% 94.70% 99.25% 99.42%

Mean Failed (%) 27.36% 5.30% 0.75% 0.58%

DL RSRP 25.70% 81.78% 55.03% 86.09%

RSRQ 5.92% 24.67% 2.68% 7.83%

DL BCH/SCH SINR 0.55% 5.60% 0.67% 0.87%

UL SINR 14.74% 3.32% 4.70% 4.35%

DL SINR 2.23% 1.90% 7.38% 0.00%

UL Capacity 0.00% 0.00% 0.00% 0.00%

DL Capacity 41.11% 10.72% 32.89% 7.83%

User Limit 22.76% 2.28% 0.00% 2.61%

No valid connection scenarios 0.00% 0.00% 0.00% 0.00%

No pathloss data 0.00% 0.00% 0.00% 0.00%

From these statistics, it is clear that the success rate (Mean Served terminals) statistics are

much better for the combined Macro and Small cells network than for the Macro network alone. It is also clear that the areas on which having separate carriers help, are in helping

reduce failures due to poor coverage, poor quality, poor SINR and low capacity.


7 Conclusion

This Use Case has shown that LTE Small Cells can be effectively planned and analysed in ASSET. As the majority of Small Cells will be deployed in dense urban and urban

environments it is highly recommended that Building Vector data and a semi-deterministic, such as MYRIAD, or a deterministic propagation model is used.

Considering the low antenna height of 4m and low TX Power of 1W (30dBm) the Small Cells provide impressive improvements in both outdoor (street level) and indoor coverage in the

vicinity of each Small Cell location. Because of the low antenna height which is well below the building height in dense urban and urban environments the interference is controlled for the

Small Cells when compared with the higher Macrocells which tend to be at or above building height.

The number of Terminals Served, in this case for a guaranteed UL Throughput of 500kbps and DL Throughput of 1000kbps, is significantly better for the Combined Macrocell and Small

Cell scenario than for the Macrocell only scenario. This is primarily due to improved indoor coverage and the capacity provided by the addition of the Small Cells.

Having separate carriers for the Macro and the Small cells networks provides additional benefits; mainly in terms of reduce failures due to poor coverage, poor quality, poor SINR

and low capacity.

Geolocated traffic and Network optimization tools, such as Symena Capesso, could be used to select the best Small Cell locations and to optimise the antenna azimuths whilst maintaining

the azimuth separation of 120o.


8 Glossary

LTE - Long Term Evolution, a technology from the 3GPP industry group RSRP - Reference Signal Received Power

RSRQ - Reference Signal Received Quality Streaming-QCI-4 - A type of data streaming service which complies with 3GPP’s QCI

(Quality Control Indicator) category 4

UL - Uplink, referring to the direction from the User Equipment to the Base transmitting station, or eNodeB for LTE

GBR - Guaranteed Bit Rate RF - Radio Frequency

SINR - Signal to Interference Noise Ratio


9 Appendix A - About the Products and modules used in this application note

9.1 ASSET 8.0

ASSET is the world’s most popular Radio Network Planning tool. It is used by over 250

customers and it allows you to:

Plan and Optimise the Radio Network Configuration

Perform Coverage and Interference Planning

Perform Traffic and Capacity Analysis

Perform financial analysis on your radio network

ASSET’s capability can be summarised as follows:

Master Site Database

Keep an accurate list of all RAN elements

Maintain key planning parameters

Act as the focal point of network management applications

Coverage Planning

Predict radio propagation

Analyse outdoor and indoor network coverage & quality

Create coverage maps by Service, UE and technology type

Neighbour & Resource Planning

Plan relations between cells

Plan IRAT handovers

Plan frequencies, scrambling codes, etc.

Traffic & Capacity

Model the performance of new Services prior to implementation

Perform traffic forecasting and capacity impact

Plan network expansion and run “What if” scenarios

ASSET is a product with excellent security, data integrity and open interfaces. A product that

can work in very large corporate environments, but can also be very user-friendly at an individual level.

9.2 Myriad

The Myriad propagation model is a Productivity Pack of the ASSET Radio Network Planning

tool. Myriad is a universal propagation model which can be used for: All main technologies:

o DVB, GSM, EDGE, GPRS, UMTS, WIMAX and LTE

Any kind of cell type:

o Micro-Cells, Mini-cells, Smalls-cells and Macro-cells.

Any kind of environment:


o Dense Urban, Urban, Suburban, Rural, Open, Seaside, Mountainous, etc.

Frequency range: 200 MHz to 5 GHz.

Use different geographical data:

o Height, Clutter and Building raster.

o Building Vectors (VBF and MapInfo TAB format).

o Line Vectors (MapInfo TAB format for the train option).

The Myriad model features a realistic channel modelling, which accounts for vertical diffraction, horizontal guided propagation and mountainous area reflection.

Figure: Myriad’s channel modelling

Other key features of Myriad include:

Pre-processing of specific geographical data, such as Morphologies (from Clutter

Data), Facets (from Height Data) and Graphs (from Building Vectors) in order to

save on overall processing time Penetration component both automatic and manual

Railway component

Antenna location correction

Speed

Accuracy

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