lte-technical-challenges-for-in-building-coverage.pdf

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Introduction

LTE technology promises to bring speeds of over 100Mbps downlink and 50Mbps uplink to mobile

users using mobile broadband applications. With 196 operators in 75 countries currently investingin the technology, LTE is now generally acknowledged to represent the future of the industry.

In turn, demand for data is running at levels that were unimaginable even a couple of years ago.

This is due to the emergence of smartphones and other high end devices running multimedia

applications such as streaming video and mobile TV. By 2015, it is predicted that total data rates

will exceed 6,300,000 terabytes per month.

Given that some 50% of total mobile traffic is said to originate or terminate within buildings, we

predict a corresponding massive increase in demand for data from our in-building networks.

The purpose of this document is to present the figures relating to this growth in data demand and

to assess how we may scale our existing in-building DAS networks to handle this growth. We

consider options such as deploying smaller cells to improve capacity in localised areas; utilising

MIMO technologies to offer higher data rates; and upgrading, all or part of our existing DAS

networks to LTE technology. The document is structured as follows:

♦ First we highlight the figures behind the hype surrounding this ever-increasing demand for

data. We look at the number of devices such as smartphones and tablet PCs, both now and

in the years to come, and multimedia services such as video, VoIP, gaming etc. These

figures will help us benchmark the requirements of future in-building network designers.

♦ Working with these figures for data demand, we must consider the performance of both

existing cellular technologies (HSPA and HSPA+) and emerging technologies (LTE andLTE-Advanced). We need to estimate how these technologies will be able to cope with

increasing demand – and for how long.

♦ One of the key factors in increasing the performance of wireless networks is the

introduction MIMO technologies. MIMO will play an important role in our decisions on future

network design. A section in this document has been dedicated to explaining multiple

antenna technologies.

♦ We consider how an in-building DAS may be designed to cope with the volumes of data

that will be required in the coming months and years. In the case of 4G networks, the

challenge from the outset will be to engineer the networks to deliver capacity, as opposed

to coverage, where it is needed.

♦ Finally we look at a couple of possible solutions for migrating a DAS to LTE with 2x2 MIMO,

with one option simply doubling up on existing infrastructure and a more novel approach

using CAT5/6 cabling to carry the DAS signals.

LTE – Technical Challenges for In-Building Coverage


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LTE – Technical Challenges for In-building Coverage

Copyright: Cellular Asset Management Ltd 2010 www.cellularasset.com Page 2

♦ This document is designed to highlight the challenges involved in designing a DAS tosupport the massive data demands generated by the proliferation of smartphones and thelike, together with applications such as video streaming and multimedia gaming. It is not theobjective to propose any solutions but hopefully to stimulate discussion.

Exponential growth in data consumption

Over the period of the last three years to 2010, the volume of data being consumed over mobile

networks has almost tripled year on year. In 2010, according to Cisco, total global mobile data

traffic was in excess of 230 petabytes per month (1 petabyte = 1,000, 000 gigabytes). This is over

three times greater than total global internet usage in the whole of the year 2000.

Whilst this rate of growth is forecast to level out during 2011, Cisco has forecast that by 2015 we

will see a 26 fold increase in 2010 rates, with monthly usage of 6.3 exabytes per month (1 exabyte

= 1,000 petabytes). Please see figure 1 below.

Moreover, Alcatel Lucent has forecast a 16-fold increase in mobile data traffic to 2015 but warned

that it could grow as high as 40 times today’s levels [2].

Source: Cisco VNI Mobile, 2011

Figure 1: Cisco Forecasts 6.3 Exabytes (6,300,000 Terabytes)

per Month of Mobile Data Traffic by 2015

This description of the growth in data rate

consumption includes some new terminology used to

describe the vast quantities of data under discussion.

The chart opposite shows the values of these new

terms, such as petabytes and exabytes relative to the

more recognisable figures such as gigabytes.

0.24 EB0.6 EB

1.2 EB

2.2 EB

3.8 EB

6.3 EB

0

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

6,000,000

7,000,000

2010 2011 2012 2013 2014 2015

Terabytes per Month 92% CAGR 2010-2015

Exabyte 1,000,000,000,000,000,000

Petabyte 1,000,000,000,000,000

Terabyte 1,000,000,000,000

Gigabyte 1,000,000,000

Megabyte 1,000,000

Kilobyte 1,000


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Smartphones, Tablet PCs and Data Hungry Applications

The general pattern of accelerating growth in usage of advanced data services is linked to a strong

uptake in the usage of smartphones and other high end devices such as Tablet PCs and mobile

gaming consoles.

Smartphones, running applications such as streaming video and interactive gaming are extremely

data hungry. In 2010, the typical smartphone generated 24 times more mobile data traffic than a

basic-feature cell phone. Cisco VNI

To make matters worse (for the network designer) the iPhone and the Android based devices willconsume 5 to 10 times as much data as a ‘regular’ smartphone.

Typically a high end smartphone will generate around 79MB per month compared with 3.3MB permonth for a basic feature set phone.

The table below gives an idea of the levels of traffic generated by different device types.

Device type Traffic Generated cf. Basic Mobile Phone

‘Basic’ mobile phone x1Smartphone x24

Handheld gaming console x60

Tablet PC x122

Laptop x515

Table 1: Figures Courtesy Cisco VNI 2011

Impact of smartphones from the Mobile Operator’s perspective

Figures collated and released by the Global Mobile Suppliers Association (GSA) show asubstantial growth in revenue throughout 2010 which has been driven by the success of the

smartphone throughout Europe, the USA and Asia Pacific.

♦ Vodafone UK: “2010 data revenue growth up 30%; driven by smartphone success”

♦ Vodafone Italy: “2010 data revenue growth up 22% ; smartphone sales 50% of total

handset sales”

♦ AT&T USA: 2010 data revenue growth up 27%; 7.4 million device sales; 4.1 million iPhone

sales in 2010

♦ PCCW Asia: >80% of new subscribers are smartphone users; 3G data revenue grew by

156% in H1 2010


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This phenomenal growth in smartphone adoption and the exponential increase in data usage is

further borne out by the following figures and predictions:

♦ Google state that 300,000 Android phones are activated worldwide daily.

♦ The ITU estimates that the global number of smartphones is expected to quadruple from

today's (2010) estimate of 200 million handsets to almost 1 billion by 2015.

Figure 2: Courtesy Global Mobile Suppliers Association www.gsacom.com

According to Informa Telecoms & Media, whils t smartphone penetration currently runs at just13%, this accounts for 65% of all mobi le cellular traffic worldw ide. This usage figure is set to

increase exponentially over the next five years with the average traffic per smartphone user

increasing by 700% by 2015.

In addition to the success of the smartphone, there are ranges of other, data hungry devices that

have recently emerged on the scene and are being adopted by the consumer at a rate:

♦ Worldwide sales of media tablets such as the iPad will reach 19.5 million by the end of

2010 and exceed 54 million in 2011. Gartner .

♦ Shipments of mobile broadband-enabled consumer products, including e-book readers,

mobile digital cameras, camcorders, personal media players and mobile gaming devices

will increase 55-fold between 2008 and 2014 with total shipments reaching 58 million units

per year in 2014. ABI Research

Given that a tablet PC can generate about five times as much data as a high end smartphone, the

potential data usage of a combination of all these devices is beyond any figure that the original

mobile networks were designed to handle.


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Predict ions on Future Demand for Data on In-building SystemsUsing these figures as a guideline we can model the potential impact on an in-building DAS of the

rapidly increasing demand for data due to:

♦ The level of penetration (market share) of smartphones increasing from 13% currently to

50% and beyond by 2015

♦ A seven fold increase in traffic per smartphone: Cisco VNI

In predicting the demand on an in-building network we make the following assumptions:

1. In an in-building scenario we assume the majority of the traffic will come from mobile phones.

We do not include laptops or other devices. (smartphone traffic + basic phone traffic =

composite traffic).

2. There will be no significant increase in the number of handsets within a given in-building

scenario as we assume the building population will not change significantly over time.

3. Although the DAS for each individual building will experience different traffic changes over

time, we can assume a prediction for a generic scenario such as a shopping centre.

Tables 2 and 3 show the predicted traffic levels as described above per device:

Table 2: Current traffic levels (MB per month)

Traffic per Month Penetration % Traffic x Penetration

Basic Phone 3.3 87% 2.871

Smart Phone 79.2 13% 10.296

Composite Traffic 13.167

Table 3: Predicted traffic levels in 2015 (MB per month)

Traffic per Month Penetration % Traffic x Penetration

Basic Phone 3.3 50% 1.65

Smart Phone 554.4 50% 277.2

Composite Traffic 278.85

Combining the figures for increase in penetration of smartphones with the seven fold increase in

data demand from these devices, we can see from the tables above that in-building traffic per

device is predicted to increase from 13.2 to 278.9 MB per month by 2015, more than a doubling of

data year on year.


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In designing an in-building network to deliver these volumes of data there are a number of options

available to us:

♦ Deploying HSPA+ and LTE technology within buildings to provide high throughput, low

latency networks.

♦ MIMO antenna systems are an integral part of LTE and HSPA+ technologies and may be

used to improve performance, by improving the quality of the radio link, and/or increasing

data throughput, under given conditions.

♦ Small cell architectures can be used to increase the capacity of a network by delivering the

data locally to a smaller number of users.

These options will be discussed in the following sections.


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Comparative Performance of Cellular Technologies: HSPA, HSPA+ and LTE

As the demand for data increases we must consider the technologies being used (within the in-

building system). Although there are more criteria than just data rates to consider when deciding

on a cellular technology, it is one of the most important and we therefore present a comparison of

HSPA, HSPA+ and LTE data rates.

HSPA and HSPA+ are well established technologies, with hundreds of networks deployed globally.

LTE rollouts began late 2010 and in-building LTE is still in the early stages. LTE-Advanced is still in

development.

(Performance figures quoted in this section are, in the large part, peak data rates, from which we

can calculate throughput rates from on-site experience. Throughput figures are quoted where

available.)

HSPA has been launched by over 99% of WCDMA operators globally:

♦ 35% of HSPA networks support up to 3.6 Mbps peak DL♦ 30% of HSPA networks support up to 7.2 Mbps peak DL

♦ 8% of HSPA networks support up to 14.4 Mbps peak DL

HSPA+ has been deployed in stages, as the technology has evolved.

The evolution of HSPA+ technologies can be seen from the data below.

♦ HSPA+ using 64QAM, supports up to 21 Mbps peak DL

♦ HSPA+ using 16QAM with 2x2 MIMO supports up to 28 Mbps peak DL

♦ HSPA+ using 64QAM and 2 x 5Mhz carrier supports up to 42 Mbps peak DL

♦ HSPA+ using 16QAM supports up to 11.5 Mbps peak UL

♦ HSPA+ using multicarrier on the uplink supports up to 23 Mbps peak UL

Further development of HSPA technologies within Release 9 and 10 aims at the following downlinkrates:

♦ Rel 9 HSPA+ combines multicarrier and MIMO in 10 MHz bandwidth for 84 Mbps peak

downlink

♦ HSPA+ beyond Release 9 should lead to peak downlink data speeds exceeding 100 Mbps


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LTE technology was first rol led out in 2010. In-building throughput figures are scarce at this

time.

The number of commercial networks launched to date is still quite low and actual throughput

figures are hard to come by. The peak data rates for LTE are as follows:

♦ Peak downlink speeds (64QAM) - supports up to 100Mbps (SISO)

supports up to 172Mbps (2x2 MIMO)supports up to 326Mbps (4x4 MIMO)

♦ Peak uplink speeds supports up to 50Mbps (QPSK)supports up to 57Mbps (16QAM)

supports up to 86Mbps (64QAM)

Table 2: Comparison of Peak Data Rates: Throughput Figures Shown Where Available.Data courtesy HSPA to LTE Advanced Rysavy Research www.3gamericas.org

MIMO technology is discussed in detail in the next section.

Downlink Uplink

Peak NetworkSpeed

Peak And/OrTypical User Rate

Peak NetworkSpeed

Peak And/OrTypical User Rate

HSPA CurrentImplementation

7.2 Mbps 5.76 Mbps

HSPA 14.4 Mbps 5.76 Mbps

HSPA+ (DL 64 QAM, UL16 QAM)

21.6 Mbps 1.5 Mbps to 7Mbps

13 Mbps peak

11.5 Mbps 1 Mbps to 4Mbps

HSPA+ (2X2 MIMO, DL 16QAM, UL 16 QAM)

28 Mbps 11.5 Mbps > 3 Mbps typi calexpected

HSPA+ (2X2 MIMO, DL 16

QAM, UL 16 QAM)

42 Mbps 11.5 Mbps

LTE (2X2 MIMO) 173 Mbps 4 Mbps to 24Mbps (in 2 x 20

MHz)

58 Mbps

LTE (2X4 MIMO) 326 Mbps 86 Mbps


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MIMO Technologies

This paper is addresses the challenges of rolling out ‘in-building’ LTE networks. MIMO technology

is a fundamental part of LTE, impacting the amount of work and the costs involved in a rollout more

than any other single item. We have therefore provided a description of MIMO concepts,

terminology and modes of operation as they relate to LTE.

MIMO is considered essential for LTE, to maximize system capacity and provide high data rates.

Both 2x2 and 4x4 designs are being considered although only 2x2 configurations are being

deployed at this time. [5]

LTE systems specify three types of antenna techniques; Diversity, Beamforming and MIMO

Fig 3: Typical Configurations for Multiple Antenna Systems

Antenna diversity can include transmit diversity or Multiple-In-Single-Out (MISO) and receive

diversity or Single-In-Multiple-Out (SIMO) configurations:

♦ MISO (transmit diversity ), uses two or more transmit antennas and a single receiveantenna. The same data is sent from both transmitting antennas simultaneously, but codedin such a way that the receiver can identify the data from each transmitting antenna. Thistechnique can make the signal more resistant to fading and is used to improve performancein poor coverage areas.


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♦ SIMO (receive diversity) uses one transmit antenna and two or more receive antennas.Only one data stream is transmitted across the path and spatial diversity at the receive endcan be used to improve SNR under poor channel conditions.

Transmit Beamforming is a technique whereby multiple data streams are transmitted over

multiple transmit antennas, and with the help of feedback from the receiver (Channel QualityInformation CQI), the relative phase of the transmitted signals can be adjusted such that they will

combine constructively at the receiver to ‘focus’ the RF beam on that device. Transmit

Beamforming can be used to improve signal reception and increase the range to a particular

receiving device.

MIMO (Multiple-In-Multiple-Out) makes use of two or more transmit antennas and two or more

receive antennas. Depending on the way MIMO is implemented, multiple antenna configurations

can be used to generate higher throughput (spatial multiplexing) or to provide a more reliable link

(diversity techniques).

♦ Spatial multiplexing is used to increase link capacity. The information to be transmitted is

divided into independent data streams and each stream is sent simultaneously from a

separate antenna (multiple spatial streams). If we have N transmit antennas then we must

also have N receive antennas. If the resultant data streams are sufficiently uncorrelated to

be distinguishable from one another, then the total throughput of the link will be N times the

single data stream.

♦ Spatial diversity can be used to increase the range and/or reliability of a link. The same

data is transmitted simultaneously over multiple independent fading signal paths and by

making use of the low probability of these signal paths experiencing deep fades at the

same time, the incoming signals can be combined to increase SNR, hence improving link

reliability and range. For effective diversity, the antennas at the both the transmitter and thereceiver must be placed ½ wavelength apart.

Single User MIMO (SU-MIMO) is commonly used in LTE systems to increase the data rate to one

user in good radio conditions. The most common downlink configuration for LTE is 2x2 SU-MIMO

using spatial multiplexing. (see Fig 4).

Mult i User MIMO (MU-MIMO). Consider two data streams, each stream originating from a different

user device (see Fig 4). MU-MIMO relies on the fact that the spatial separation between the user

devices is sufficient that the information arriving at the receive antennas will have uncorrelated

paths. This maximises the potential capacity gain at the receiver (the eNode via DAS antenna).

One of the design motivations of the LTE standard is to keep the terminal or mobile device costlow. Therefore in order to minimise actual transmit antennas on the mobile device, multiple userMIMO (MU-MIMO) is being considered as an attractive option.


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Fig 4: SU-MIMO and MU-MIMO configuration

To summarise the above, MIMO is a method of using more than one antenna at the transmitter

and receiver to improve communications performance. MIMO has the potential either to increasethe capacity of networks or to enlarge the area of a given cell without the need for additionalspectrum.


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Correlation in MIMO Channels

For MIMO to be effective in achieving its objectives of increased range and capacity, the

environment in which it is deployed must provide sufficient multi-path (reflected waves). This is

referred to as non-line-of-sight (NLOS) transmission which typically occurs in an indoor

environment.

In this so called ‘rich scattering’ environment, the transmitted signals bounce off objects such as

walls, such that they are received with distinctly different profiles at the receive antennas; i.e. the

signals are easily distinguishable from one another. In mathematical terms, the signals are de-

correlated at the receiver.

Conversely, in an environment with purely line-of-sight LOS characteristics. there is one

predominant signal arriving at the receiver. The advantages of MIMO cannot be as easily realised

as the signals are no longer de-correlated. Further description is beyond the scope of this

document; however more detail is available on request from CAM.

MIMO is a crucial technology for improving in-building cellular coverage. In a rich scattering

environment with a high signal to noise ratio, a MIMO system can deliver between 70% to 100%throughput and capacity gains over a single input-single output (SISO) deployment. The rich

scattering environment describes most in-building environments and in-building distributed antenna

systems (DASs) can provide high signal quality. (ADC – Jun e 2010)

A challenge for radio planners is leveraging the maximum performance from MIMO systems, this

will require in-building systems designed to provide a sufficiently multi-path rich environment while

still achieving a high signal to noise ratio.


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Challenges for In-building Solutions

Thus far in this document we have highlighted the soaring increases in data consumption mainly

due to smartphones using data hungry multimedia applications. Predictions for data consumption

going forward show more than a doubling of traffic year-on-year from 2011 to 2015.

This raises the question: how long can the existing 2G/3G in-building DASs cope with the data

demands upon them and what would be an appropriate upgrade path to the next generation of

networks?

How long can an existing DAS support the increasing traffic?

In order to estimate how long an existing DAS can support the increasing traffic levels we must

make a couple of assumptions:

♦ For sites that can split into smaller cells the capacity of the site may be doubled for a

doubling of cells.

♦ Network support for higher HSPA+ without MIMO will also lift capacity by a factor of two

As each of these changes doubles capacity of the site we can see that the existing DAS will be

able to support traffic growth for another couple of years within any particular building before MIMO

becomes necessary.

Added to this is the fact that neither MIMO nor Small Cell topologies will be added as a network

wide upgrade, but will be deployed in localised areas only. The network upgrades can be

performed gradually over time, spreading both the costs and the risks as we learn from each stage

of an upgrade.

What Options are Available for Upgrading an Exist ing In-building DAS?

♦ Reducing cell size by sectorisation or us ing ‘small cells’ . Large buildings can be

divided into smaller cells (or sectors), reducing the number of users per cell (or sector),

thereby increasing capacity. The disadvantages are that there are physical limitations to

how small cells can be made; smaller cells may mean more cells which in turn require more

Node-Bs, which require more space and more power. Re-cabling of the system each time a

small cell is added can be expensive.

♦ Increasing data rates with MIMO. This has the advantage that capacity can be increased

without using more spectrum. This option could prove expensive if cabling had to be

doubled up; however, there are options available for running multiple antennas over one

cable, or over an Ethernet link.

♦ Deploying LTE to specifi c areas within the building. This is undoubtedly the way LTE

will be deployed for the reasons given earlier i.e. capacity is only delivered where it is

needed. Any upgrade to LTE technology will follow this upgrade path for reasons of cost

and efficiency. The advantages of MIMO are that capacity can be increased without using

additional spectrum. The main disadvantage as mentioned above is doubling up on cabling

to the multiple antennas.


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What Options are Available for Deploying a New In-building DAS?

It is a fact that GSM/UMTS will comprise the overwhelming majority of subscribers over the next

five to ten years, even as new wireless technologies are adopted. Therefore, even in the light of

large increases in data demand, a new DAS deployment would most likely still be based on a

building-wide 2G/3G network with smaller areas of high capacity LTE networks, only where the

data demand is required. The LTE sections of the network would be similar to the upgrade optionsgiven in the previous section.

Estimated costs from CAM, for a new DAS installation comprising materials described below, areas follows:

♦ 20 antennas

♦ 700m co-axial cable

♦ 10 splitters

♦ 10 couplers

Costs:

1. 2G / 3G / 4G SISO System: £22,000 to design and install

2. 2G / 3G / 4G 2 x 2 MIMO System: £32,000 to design and install

3. 2G / 3G / 4G 4 x 4 MIMO System: £46,000 to design and install

Figures are based on the fact that the materials are doubled in each case but the labour required

for each installation does not double. As a percentage, a 2 x 2 system would be 45% more

expensive to install and a 4 x 4 system 109% more expensive.

These costs however would only be applicable if we were to deploy MIMO over an equivalent area

to the SISO installation. As we have seen in this document, this rollout scenario may not be the

most suitable, or the most cost effective.

To deliver ‘pools’ of high capacity, using MIMO, only where it is needed would probably cost more

from the point of view of planning and site surveys but will ultimately be cheaper than deploying

MIMO throughout the building. This issue is open to discussion.


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A Novel Approach to Deploying In-bui ld ing LTE Coverage: (Cellu lar-over-LAN)

In previous sections we have discussed the advantages and disadvantages of deploying MIMOtechnologies for in-building networks. One of the main disadvantages is the cost of running multiplecables to the multiple antennas in a MIMO system. There are a few options whereby multipleantennas can be fed from a single feeder. One option involves feeding the antennas via theexisting CAT5/6 cabling within the building.

This solution, called Mobile Access VE “is designed to deliver in-building LTE cellular services overan existing CAT 5/6 LAN infrastructure, while maintaining full Ethernet and wireless LANcapabilities.” The vendor claims the following performance figures and facilities:

♦ Extends carrier-grade, 5-bar coverage for 2G, 3G, 4G services with MIMO

♦ Reduces installation time by half, as compared with conventional solutions

♦ transparently coexists alongside the LAN without impacting LAN performance

♦ Supports connectivity to any type of operator RF capacity source

♦ Offers proactive end-to-end network monitoring

♦ Plug-and-play design scales cost-effectively, allowing customers to choose where new

services are activated

Results from an actual Mobile Access VE installation give throughput figures for an indoor LTE

deployment:

♦ -70dBm coverage was tested in 90% of the building, following MobileAccessVE deployment

♦ Each VE Pod covered 10,000 square feet.

♦ Spatial multiplexed 2x2 MIMO and 64QAM was verified using the LTE LG USB dongle

♦ The measured data throughput at MIMO configuration was:

♦ 15 Mbps for UL (uplink) data speed

♦ 40 Mbps for DL (downlink) data speed

♦ SISO performance equivalents offer less than 35% of MIMO throughput (15Mbps UL,

25Mbps DL)

(http://www.mobileaccess.com )

This solution provides an advantage in its quick and easy installation times and MIMO support at

4G, without impacting on the existing LAN performance. MobileAccess VE is also the first cellular

solution validated with the Cisco® Unified Wireless Network. More detail is available on request

from CAM.


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LTE Femtocells

A Femtocell is a small base station, designed to be deployed within home or small business

premises to provide enhanced coverage. The coverage and capacity made available by using the

small cell approach within buildings is well suited to LTE deployment.

LTE Femtocells are supported within 3GPP as early as Release 8 (2008) and are identified as

Home eNode-Bs (HeNB). However, unlike the 3G Femtocell, there is currently no defined

architectural standard in place.

The level of interest from operators is driving the Femtocell ecosystem forward at a pace.

Enterprise Femtocells that could provide coverage in large buildings are now in the pipeline,

supporting femto-femto handovers.

Cellular Asset Management will be happy to discuss the potential of Femtocells upon request.

Conclusions

The purpose of this document has been to promote discussion on the best way to serve the

soaring levels of data demand expected over the next few years, using an in-building DAS system

and new technologies such as LTE. The main points are:

♦ Smartphone devices are expected to more than double the traffic demanded of in-buildingsystems year on year from 2010 to 2015.

♦ To upgrade an existing in-building DAS for the increase in data there are two main options:reduce the size of each cell and increase the data rates supported by the DAS.

♦ To support the data rates of HSPA+ and LTE the in-building systems will need to beupgraded for MIMO antenna technology.

♦ Femtocell technology for LTE could provide small cell capacity solutions, although it is still

in development.♦ Alternative distribution systems such as MobileAccess VE could provide a quick and

simpler upgrade path with extra capacity being added to areas as the traffic increases.

Do we upgrade now? In the next two years? More likely we will see networks upgrade gradually,

providing extra capacity only in localised areas where it is required and leaving the 2G/3G DAS

installations to handle the wider area coverage.


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References

1. Cisco Visual Networking Index: Global Mobile Data: Traffic Forecast Update, 2010–2015. www.cisco.com

2. Mobile Broadband Growth Report : Published by the Global mobile Suppliers Association (GSA)

www.gsacom.com Feb 2011

3. The IET - Engineering and Technology Magazine: Article: Will mobile networks be ready for the 4G data deluge?http://eandt.theiet.org/magazine/past-issues/index.cfm

4. Ofcom -The Communications Market 2010 (August) http://stakeholders.ofcom.org.uk/binaries/research/cmr/753567/CMR_2010_FINAL.pdf

5. Agilent Technologies. http://www.home.agilent.com/agilent/application.jspx?nid=-34563.0.00&lc=eng&cc=GB LTE implementation of MIMO

6. HSPA to LTE Advanced, Rysavy Research Sept 2009 http://www.4gamericas.org/

7. NEC Shows How Small Cell LTE Deployment is Smarter Way to Sustainable Futu re: Mobile BroadbandMobile World Congress – Feb 2011 http://www.nec.com/

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