Small cells are Low-powered radio access nodes, Operate in licensed and unlicensed spectrum, Short range mobile phone base stations, Range from very compact residential femto-cells of area 10 meters to larger equipment used inside commercial offices or outdoor public spaces of area 1 or 2 kilometers, "small" compared to a mobile macro cell, with range of a few tens of kilometers, Complements mobile phone service from larger macro cell towers, Offer excellent mobile phone coverage and data speeds at home, in the office and public areas for both voice and data, Developed for both 3G and the newer 4G/LTE radio technologies. Femto cells are Initially designed for residential and small business use with a short range and a limited number of channels. Femtocell devices use licenced radio spectrum. Femto cells must be operated and controlled by a mobile phone company, One cell with one mobile phone operator. When in range, the mobile phone will detect cell and use it in preference to the larger macrocell sites. Calls are made and received in exactly the same way as macrocell. Except, the signals are sent encrypted from the small cell via the public or private broadband IP network to one of the mobile operators main switching centres.

1. SMALL
CELLS-1
FEMTO
CELLS

2. Small Cells
TOPICS
 Small Cell Types
 Femto cell :
 Introduction
 Liscence
 Power and Quality
 Capacity
 Security and Management
 Compatibility
 Standards
 Architecture
 Components and building
blocks
 System software
 Evolution
 Installation
 Working
 Handover
 Location lock
 Reparenting
 Security
 Timing and synchronization
 Issues
 Reference

3. Small Cells
 Low-powered radio access nodes.
 Operate in licensed and unlicensed spectrum.
 Short range mobile phone base stations.
 Range from very compact residential femto-cells of
area 10 meters to larger equipment used inside
commercial offices or outdoor public spaces of
area 1 or 2 kilometers.
 "small" compared to a mobile macro cell, with
range of a few tens of kilometers.
 Complements mobile phone service from larger
macro cell towers.
 Offer excellent mobile phone coverage and data
speeds at home, in the office and public areas for
both voice and data.
 Developed for both 3G and the newer 4G/LTE radio
technologies.

4. Small Cells
TYPES :
 Small cells may encompass femtocell, picocell and
microcell.
 Small cells provide a small radio footprint, ranging
from 10 meters within urban and in-building
locations to 2 km for a rural location.

5.  Picocells and microcells can also have a range of a
few hundred meters to a few kilometers,
 But they differ from femtocells in that they do not
always have self-organising and self-management
capabilities
Small Cells
TYPES :

6.  Small-cell
networks can also
be realized by
 Distributed radio
technology using
centralized
baseband units
 Remote radio
heads
 Beam-forming
technology
 Feature central
management by
mobile network
operators.
Small Cells
TYPES :

7. Femto Cells
 The most common form of small cells.
 Initially designed for residential and small business
use with a short range and a limited number of
channels.
 Femtocells with increased range and capacity is
frequently known by names like:
 metrocells,
 metro femtocells,
 public access,
 enterprise femtocells,
 super femtos,
 Class 3 femtos,
 greater femtos
 microcells

8. Femto Cells-
Licence
 Femtocell devices use licenced radio spectrum.
 Must be operated and controlled by a mobile
phone company.
 One cell with one mobile phone operator.
 When in range, the mobile phone will detect cell
and use it in preference to the larger macrocell
sites.
 Calls are made and received in exactly the same
way as macrocell.
 Except, the signals are sent encrypted from the
small cell via the public or private broadband IP
network to one of the mobile operators main
switching centres.

9.  Making and receiving calls uses the same
procedures and telephone numbers as macro-cell.
 All standard features- call divert, text messaging,
web browsing are available in the same way.
 Data services should operate more quickly and
efficiently due to the short range involved.
Femto Cells-
Licence

10. Femto Cells-
Power & Quality
 Small cells operate at very low radio power levels.
 Less than cordless phones, Wi-Fi or some other
household equipment.
 This substantially increases the battery life, both on
standby and talk time.
 In close vicinity to the handset or mobile device,
hence..
 call quality is excellent.
 data devices can operate at full speed.

11. Femto Cells-
Capacity
 Most indoor products have standard capacity of 8.
 The smallest femtocells can handle up to 4
simultaneous active calls from different users.
 Larger small cell designs for business (enterprise) or
public areas use can handle 16, 32 or more
concurrent calls or data sessions.
 A few of the latest multi-mode 3G and LTE small
cells can cope with up to 64 3G and 128 LTE
concurrent active sessions.
 Restrictions can be applied on who can access a
small cell.

12. Femto Cells-
Security & Management
 Small cells encrypt all voice and data sent and
received.
 Ensures a high level of protection from sniffing or
snooping.
 In order to reduce operational and installation costs,
 these units are self –installing
 sense which frequency to transmit on and power level to
use.
 Unlike large outdoor mobile phone base stations they –
 don't require specialists to design, calibrate or configure
themselves.
 minimise the on-going cost of maintaining them.
 They have remote management from the network
operator to upgrade the configuration and software as
required.

13. Femto Cells-
Compatibility
 Compatible with 3G and 4G mobile phones.
 No additional software required.
 Same interface for radio to mobile phone and to
core network.
 Compatible with existing mobile phone networks,
phones and services.
 3G UMTS- Small cell subsystem connects into
operator's core network using IU interface same as
traditional outdoor cell sites.
 LTE- Standard S1 interface to the core is used,
conforming to standard radio transmission
frequencies and protocols of today.

14. Femto Cells-
Compatibility
 MSC and data switch (SGSN) communicate with
the small cell controller same way as other mobile
calls.
 Services like phone numbers, call diversion,
voicemail operate in exactly the same way and
appear the same to the end user.
 The small cell appears to the standard 3G or LTE
phone as just another cell-site from the host mobile
operator,
 Can be used by any phone including roamers from
abroad.

15. Femto Cells-
Interface-Standards
 The connection between the small cell and
controller/gateway is the Iu-h interface.
 It uses a secure IP encryption (IPsec) to avoid
interception.
 LTE uses the standard S1 interface protected by
IPsec.
 Authentication of the small cell ensures valid access
point.
 Each small cell connects with a small cell gateway
over broadband IP.
 Gateway consolidates hundreds of thousands of
small cells into a single IU or S1 interface.
 Carries thousands of concurrent calls and data
sessions.

16. Femto Cells-
Standard
 3GPP release 8 and 9

17. Femto Cells-
Architecture
 Complete working of a mobile phone base station
is inside femtocell .
 Additional functions like RNC (Radio Network
Controller) processing also included.
 May have Core network element to manage data
sessions locally.
 The extra capabilities demand it to be self-installing
and self-configuring.
 Requires S/W to scan environment continuously for
frequencies, power level , scrambling codes.
 Femtocell gateways aggregate large numbers of
femtocell connections (typically 100,000 to 300,000).
 These are first securely connected through high
capacity IP security firewalls.

18. Femto Cells-
System Architecture
 Industry has standardised on common solutions
published by the 3GPP standards committees.
 There are three architectures, one for each of the
three main different radio technologies-
 UMTS - the most common and used for today's 3G UMTS
phones
 CDMA- applies to 3G CDMA femtocells compatible with 3G
CMDA phones
 LTE- the 4G standard uses a different approach, having
incorporated small cells into the system from the outset.
3GPP (3rd generation partnership project)
UMTS(Universal Mobile Telecommunication System)
CDMA(Code Division Multiple Access)
LTE(Long Term Evolution)

19. Femto Cells-
Architecture
 3GPP HNB femtocell network architecture:
 Home NodeB (HNB): 3G UMTS terminology for
femtocell access point within the home, or other
location.
 Incorporates the capabilities of a standard Node B as
well as the radio resource management functions
found within a Radio Network Controller, RNC.

20. Femto Cells-
Architecture
 HNB Gateway (HNB-GW): Entry point to the core
network.
 The link into the core network is provided over Iu-cs
and Iu-ps interface.
 Already used for links from Radio Network Controllers
to the remaining core network.
 Functions:
 Provides authentication and certification to allow only
data to and from authorised HNBs.
 Aggregates traffic from a large number of HNBs and
provides an entry point into the operator core network.
 Provides a mechanism to support enhanced features
such as clock sync distribution, other IP based
synchronisation

21. Femto Cells-
Architecture
 Iu-h Interface: Used to provide the link or interface
that connects the HNB with the HNB-GW.
 Includes a new HNB Application Protocol, HNBAP that
provides the high level of scalability required for the
HNB deployment in ad-hoc fashion.

22. Femto Cells-
Architecture
 CDMA

23. Femto Cells-
Architecture
E-UTRA: Evolved UMTS Terrestrial Radio Access
UE: User Equipment
Uu: Unique user
HeNB: Home e-node B
GW: Gateway
MME: Mobility Management Entity
CSG: Closed Subscriber Group
HSS: Home Subscriber Server
SGW: Serving Gateway
PGW: Packet data n/w Gateway
PCRF: Policy and Charging Rule Function
IMS: IP Multimedia Subsystem

24. Femto Cells-
Architecture
 LTE femtocell architecture:
 Required to take account of the LTE SAE, System
Architecture Evolution requirements.
 Provides a much flatter overall network architecture.
 This has many advantages in terms of network
simplification.
 Key element in enabling much lower levels of latency -
a key requirement for LTE.
 Allows maximum flexibility and scalability to ensure
that the deployment can be easily incorporated into
the existing structures.
 Deployment of femtocells is achieved on an ad-hoc
basis, this forms a large requirement for the system.

25. Femto Cells-
Enterprise Small Cells
 The same technology and architecture used.
 Small cells have higher capacity and slightly higher
RF power to give a larger range.
 Small cells may co-operate in clusters to provide
seamless service.
 For larger enterprises, a small cell controller may be
used to provide additional local services including
direct connection to the enterprise network.

26. Femto Cells-
Urban and Rural Small Cells
 Public areas use specially designed urban small
cells (metro-cells) which are also based on the
same architecture.
 Take advantage of Femto-cell gateway, sharing its
use between residential, enterprise and urban
installations.
 Requirement:
 weather proof and vandal proof.
 Operating in harsh unsupervised environments with wide
temperature fluctuations.
 Urban small cells are installed by the network
operator.
 Broadband IP connection back to the regional
switching centre (backhaul) is also required.

27. Femto Cells-
Components and Building Blocks
 RF Front-End connects to the antenna-
 converts the digital signals to and from radio
transmissions
 Baseband processing –
 analyse and decode the complex transmissions into
meaningful data
 Control processing runs the software –
 to communicate with handsets and the femtocell
gateway.
 Memory chips, read/write chip for transient data
(RAM)
 Read only chip which holds the program (ROM)
 Crystal frequency oscillator , provides a very
accurate clock-
 important for synchronising the timing of signals to
handsets.

28. Femto Cells-
Application Software
 Software controls overall operation of femtocell:-
 what the femtocell does on startup and how quickly it
is ready to make/receive a call
 how it searches out and determines the correct
frequency/scrambling codes to transmit on
 how quickly it responds to a changing environment
(e.g. someone opening a window)
 What handover options are available when
entering/leaving the home
 what features are provided specifically for
enterprise/business users
 what self-service management features are included,
such as setting up a list of barred/enabled phones
 what diagnostic features are incorporated to reduce
the cost of remote diagnostic/maintenance and
customer care

29. Femto Cells-
Evolution

30. Femto Cells-
Installation
 Femtocells require no radio planning.
 Reduced impact on the outdoor macrocellular
network, ( low power, no wall penetration.
 No negotiation for site acquisition.
 No ongoing running costs per site for site rental,
power or backhaul transmission .
 Femtocells are “self configuring”. (directly
connected to RNC for configuration).
 Can be managed on rental basis, like TV or Set Top
Box.
 Standards needed for enforcing interoperability.
 Device can be used around the world.
 Drastically reduced cost from mass production.

31. Femto Cells-
Installation
 Indicators are required to show:
 Broadband signal connection active and online.
 Connection into the operator’s network active and online.
 If a mobile phone is “camped” on the femtocell.
 When a voice or data call is active.
 “camped” – only determined by mobile when an
active call is made / received.
 Mobile network only aware of “location area” of
each phone.
 Phone sends location update message, when
changes cell, to network for broadcast to all
cellsites in the paging area.

32. Femto Cells-
Installation
 Each femtocell may be configured as an individual
paging area.
 ensures femtocell knows when the mobile phone enters the
home zone.
 impacts on the sizing capacity of the MSC and SGSN which
initiate the paging messages
 potential for increased numbers of location update
messages to the network.

33. Femto Cells-
Installation
 A straightforward installation is connecting the box
to the broadband DSL line and power.
 If GPS equipped, it needs to be located near to a
window.
 Femtocells including WiFi and/or PC connections,
onboard configuration website required.
 DHCP should be enabled for all wired and wifi
connections.
 WPA should be enabled for wifi requiring
reconfiguring the WPA clients on each laptop.
 Benefits of using mobile broadband than WiFi -more
automatic security setup.

34. Femto Cells-
Two stage registration process:
 The femtocell has standard, common software
installed in the factory
 On first powerup, it connects to the vendor’s
website, sending its serial number.
 The vendor’s website downloads any firmware and
security updates to the device
 Vendor’s website uses serial number to identify the
mobile, redirects femtocell to contact mobile
operator’s servers.
 Femtocell registers with the mobile operator’s
network and receives operator specific
configuration (operating frequency, max power
level, cell id, paging area)

35. Femto Cells-
Two stage registration process:
 The mobile operator network also downloads the list
of phones allowed to use the femtocell
 indication can be given to the customer before a call to
show applied billing rates.
 To restrict use of femtocell to authorised phones where the
customer requests it.
 The femtocell is authorised to transmit by the mobile
operator’s network and becomes part of the live
operation.
 The customer can make or receive calls using the
femtocell.

36. Femto Cells-
Outdoor cellsite installation
 Complex radio planning tools are used to analyse
the area to be covered.
 Using topology of the area , simulation run to identify
best locations for cellsites.
 Operators’ targets for their plans:
 coverage (able to use phone in any part of the
country, inside buildings, cars, moving trains etc)
 capacity ( ensuring enough traffic channels for
everyone in an area to make and receive calls).
 Radio parameters are computed - maximum
transmission power, frequency hopping (for 2G),
coding sequence (for 3G), angle of the transmission
antenna , list of neighbour cellsites to handover
to/from.

37. Femto Cells-
Outdoor cellsite installation
 Transmission network connects cellsite to core network of
the operator via leased lines, microwave links or high
capacity SDH fibre owned by the operator
 These are concentrated into an RNC (Radio Network
Controller for 3G) or BSC (Base Station Controller for 2G).
 The transmission planners will allocate capacity from the
cellsite to the central switching centre.
 Includs port mappings for each input and output across
every transmission hub.
 Actively configured at the appropriate point in the
cellsite rollout.
 All basestations and RNCs are managed by a central
Network Management System.
 Radio configuration parameters periodically
downloaded into basestations via NMS for
synchronization.

38. Femto Cells-
Outdoor cellsite installation
 Fault management systems used-
 to capture, collate and analyse alarms and fault
indications from the network equipment.
 Performance management systems used –
 to monitor the capacity and overall throughput of the
systems.
 to ensure maximum utilisation of the network.
 to identify additional capacity or coverage required

39. Femto Cells-
Working

40. Femto Cells-
Handover
 Handover/handoff - process by which:-
 a mobile phone switches between different cellsites
during a phone call
 continues with seamless audio in both directions.
 Femtocell users need this capability when entering
or leaving their home .

41. Handover in Mobile phone Mobile phone
 As we move around when on a call, mobile phone
continuously measures the signal level and quality
from nearby cellsites.
 Current active basestation determines when and
where to initiate a handover sequence.
 Complex algorithms uses all available capacity
whilst reducing call dropping during a handover.
 3G systems and CDMA are complex as mobile may
be actively connected to more than one cellsite at
the same time.
 Called soft handover- same signal transmitted by a
mobile phone to be picked up by multiple cellsites

42. Femto Cells-
Handover
 In Femto cell
 Do not implement soft handover.
 All calls switched instantly to or from femtocell and
the external outdoor cellular network.
 This is known as “hard handover” .
 Not audible or noticeable to the caller.
 Handover between 2G and 3G can occur-GSM and
UMTS.
 3G systems more common because of higher traffic
capacity and lower costs.

43. Femto Cells-
Handover


44. Femto Cells-
Handover effects
 Usability
 User unaware whether using 2G or 3G mode.
 Calls originating using 2G continues until
completion, even entering the femtocell.
 No automatic handover into the femtocell zone.
 Billing Implications
 Charges based on where the call originated.
 i.e. inside or outside the femtocell coverage.
 Irrespective of discounts offered inside/outside
femtocell.
 Clarity of the billing mechanism.
 No large loophole for revenue loss to exploit.
 Forced handovers are possible.

45. Femto Cells-
Handover optimization
 Adding femtocells to the neighbour lists of the
outdoor macrocells.
 Adding some smarts into the mobile phone.
 Making the femtocell as clever as possible.

46. Femto Cells-
Location Lock
 Location lock prevents a femtocell from changing its
location without network operator’s awareness and
permission.
 Emergency Call Location: Operators report the
location of emergency calls.
 Femtocell only operates at the specified location.
 Any moves to a new address are properly registered
and tracked.
 Spectrum Use: Femtocells must be used at the
correct frequencies for the area they are located.
 Disabled when away from licenced territories. (e.g.
abroad on trip).
 Commercial: Operators can charge additional fee
to process a femtocell relocation.
 Includs updating the registered operating address.

47. Femto Cells-
Location Lock implementation
 Femtocells are connected via broadband IP and are
associated with an IP address.
 If wired broadband and femtocell have same provider,
IP address may associate with registered physical
address.
 But domestic customers allocated dynamic IPv4
addresses-
 restrict identification to area served by pool of IP addresses.
 Sniffing external 2G and 3G cellsites: Femtocells can
detect and remember the cellsite IDs, which shouldn’t
change frequently.
 GPS: Although indoors, femtocells can have low power
and sensitive GPS receiver for:
 Location and look-up for licenced frequencies.
 long term frequency clock accuracy.

48. Femto Cells-
Re-Parenting/Re-homing
 Network management operation- cellsite is switched
across to a different controller (BSC or RNC).
 Managed task under the planning and direction of
the network planning and operations department.
 Organic Network Growth: As networks grow, new
controller is installed and some cellsites swapped
across to balance the load.
 Swanky New Products: Several controllers can be
replaced by single, larger product with increased
capacity /more cost effective technology.
 Grooming: Existing transmission and location of
controllers may be organised to be more efficient.
 Commercial changes: For changing commercial
agreements.

49. Femto Cells-
Security
 Identity Theft - No security loophole to exploit.
 Authentication take place in the operator’s network
before allowing voice or data calls through the system.
 Phone-Tapping – Femtocells encrypt their voice and
data traffic using secure tunnels (IPsec) between the
femtocell and operators network.
 More secure than mobile phone outdoors with no
encryption is used.
 Bill Avoidance – It is proposed to include a SIM card
in the femtocell to validate the owner of the device.
 Stolen or compromised units can be disconnected
from the network.

50. Femto Cells-
Security
 Use of IPsec: In order to ensure femtocell security
IPsec or IP security is used.
 Defined by the Internet Engineering Task Force (IETF).
 Femtocell Secure Authentication: Femtocell
security procedures using SIM cards authentication
or X.509 are used.
 Wireless link security: To ensure that unauthorised
users do not connect or take over the femtocell
Techniques include femtocll coverage area not
exceeding the physical area where the femtocell is
to be used.
 EAP, Extensible Authentication Protocol: for
providing femtocell security.

51. Femto Cells-
Timing and synchronisation
 GPS: Provides very accurate frequency and phase
alignment but little extra hardware.
 Can also determine the location of the device.
 NTP (Network Timing Protocol): Operates across
domestic quality broadband Internet, low cost but
potentially long time to acquire and lock-on to
frequency
 Network sniffing: Nearby macrocells used as an
alternative clock source.
 Synchronization needed for
 Supply frequency information to handsets to
synchronize to base stations.
 Ensure reliable handover
 Interference reduction
 Ensures femtocell to be aware of adjacent cell sites

52. Femto Cells-
Packaging
 Standalone
 Integrated with existing DSL broadband modem
 Cable Modem
 TV Set-Top Box

53. Femto Cells-
Issues
 Interference issues : Femtocells operate within spectrum
shared with other cellular base stations.
 3G and 4G are able to tolerate interference and single
channel working.
 Spectrum issues: Spectrum is scare resource, especially
when large amounts of data are required.
 Careful planning required.
 Regulatory issues: Femtocells need regulatory approval
to operate in licensed or regulated spectrum in each
country.
 International agreement may also be required,as private
individuals take femtocells from one country to the next.
 Health issues: RF radiation issue with health and safety.
 Power levels emitted by femtocells are small - no greater
than most Wi-Fi access points ,common in very many homes.
 As per industry, no health issues of any concern.

54. Reference:
 http://www.thinksmallcell.com
 https://en.wikipedia.org/wiki/Small_cell
 www.smallcellforum.org
 www.radio-
electronics.com/info/.../femtocells/femto-
cells...basics.php
 www.techrepublic.com/.../data-center/pros-and-
cons-of-using-femtocells
 https://en.wikipedia.org/wiki/Femtocell
 http://www.rfwireless-world.com
 http://www.rfwireless-world.com/Tutorials/femtocell-
architecture.html