femtocell

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femtocell

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Femtocell Definition

• A small cellular base station, designed for use
  in residential or enterprise.
• Connects to the service providers network via
  broadband.
• Support 2 to 5 mobile.
• Allows service providers to extend service
  coverage indoors.

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Femtocell Definition

• Confidential
• Incorporates the functionality of a typical base
  station but
• extends it to allow a simpler, self contained
  deployment.
• The concept is applicable to all wireless
  standards, including
• UMTS, GSM, CDMA-2000, TD-SCDMA and WiMAX
  solutions.

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Benefits for end-users

• The main benefits for an end-user are the
  following
• Excellent network coverage when there is no
  existing signal or poor coverage.
• Higher capacity, which is important if the
  end-user uses data services on his/her mobile
  phone.
• Depending on the pricing policy of the MNO,
  special tariffs at home can be applied for calls
  placed under femtocell coverage.
• For enterprise users, having femtos instead of
  DECT or Wi-Fi dual mode phones enables them to
  have a single phone, so a single contact list etc.

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Benefits for end-users

• Depending on the pricing policy of the MNO,
  special tariffs at home can be applied for calls
  placed under femtocell coverage.
• For enterprise users, having femtos instead of
  DECT or Wi-Fi dual mode phones enables them to
  have a single phone, so a single contact list
  etc.

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Architectures

• Home Node B (HNB/HeNB)
• In 3GPP terms, LTE femto-cells are called Home
  Node Bs for HSPA and Home eNode Bs for LTE.
  H(e)NBs are typically associated with
  uncoordinated large scale deployments and
  therefore the connection to the operators core
  network needs to be realized efficiently.

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Architectures

• Collapsed stack
• The approach standardized by 3GPP in Release 8 is
  to collapse network functionality into the
  femtocell, so it includes not just the base
  station itself but also the controller that
  enables local radio resource control. This
  connects back to the mobile operator core at a
  higher point for central authentication and
  management. This addresses the scalability
  concerns above, as the resource is located
  locally.

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Architectures

• Historic approach/cellular base station
• One approach for a femtocell is to use the
  traditional base station architecture. In this
  case, the femtocell is a base station, connecting
  to the core network using a standard interface.
  The slight difference from a typical base station
  deployment is that the backhaul would be carried
  over broadband ("Iub over IP") which may have
  quality security concerns. A more significant
  drawback of this architecture is that
  standards-based base station controllers are
  designed to support only a limited number of
  high-capacity base stations, not large numbers of
  simple ones

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Architectures

• SIP or IMS
• The final, and most sophisticated structure is to
  move to a full IP-based architecture. In this
  case, even more functionality is included within
  the femtocell, and the integration to the core is
  done using an IP-based technology

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Issues

• Femtocells are a complicated technology and there
  have been a number of issues and concerns which
  need to be addressed.
• Interference
• The placement of a femtocell has a critical
  effect on the performance of the wider network,
  and this is one of the key issues to be addressed
  for successful deployment. Because femtocells can
  use the same frequency bands as the conventional
  cellular network, there has been the worry that
  rather than improving the situation they could
  potentially cause problems.
• As more analysis has been done, and more
  operators have deployed it is clear that so long
  as femtocells incorporate appropriate
  interference mitigation techniques (detecting
  macrocells, adjusting power and scrambling codes
  accordingly) then this need not be a problem.

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Issues

• Equipment location
• There are issues in this regard for access point
  base stations sold to consumers for home
  installation, for example. Further, a consumer
  might try to carry their base station with them
  to a country where it is not licensed.
• Other regulatory issues relate to the requirement
  in most countries for the operator of a network
  to be able to show exactly where each
  base-station is located, and for E911 requirements
  to provide the registered location of the
  equipment to the emergency services.

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Issues

• Quality of service
• In shared-bandwidth approaches, which are the
  majority of designs currently being developed,
  the effect on Quality of Service may be an issue.

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Issues

• Controversy on consumer proposition
• The impact of a femtocell is most often to
  improve cellular coverage, without the cellular
  carrier needing to improve their infrastructure
  (cell towers, etc.). This is net gain for the
  cellular carrier. However, the user must provide
  and pay for an internet connection to route the
  femtocell traffic, and then (usually) pay an
  additional one-off or monthly fee to the cellular
  carrier. Some have objected to the idea that
  consumers are being asked to pay to help relieve
  network shortcomings. On the other hand,
  residential femtocells normally provide a
  'personal cell' which provides benefits only to
  the owner's family and friends.

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Features of Femtocell

• Operates in the licensed spectrum
• Uses fixed broadband connection for backhaul
• It is managed by the NAP
• The backhaul service provider may be different
  from NAP/NSP
• Principally intended for home and SOHO
• Lower cost than PicoBS
• Smaller coverage (low power) than PicoBS
• Smaller number of subscriber (ten or less) than
  PicoBS
• Higher density

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Deployment

• Irregular deployment will incur inevitable
  interference

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FAP System Specifications Requirements

• A Femto Access point (FAP) is a low-power BS,
• operating in licensed band, intended to
• Be end user installed without service provider
  manual
• configuration (plug and play).
• Provide service for a limited number of
  concurrent users
• over small areas such as the home and SOHO
• environment.
• Use a shared broadband connection for backhaul
  that may
• be operated by a different Service Provider.
• Support limited user mobility (low speed,
  infrequent need
• for handover).

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FAP Value Proposition
Benefits to consumer Benefits to operator
Fear
Reduces cost(free calls) Counters threat from VoIp
Improves coverage Greed
Simplicity Single Device can be used by multiple users Increases both coverage and capacity
No need for new expensive device Reduces churn
Increases 3G adoption
Works with all existing handsets
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WiFi vs. FAP
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WiFi vs. FAP

• Licensed vs. unlicensed spectrum
• Operator need to use its 3G spectrum
• Which will reduce the overall spectrum available
• Tight frequency reuse planning
• QoS better in licensed than unlicensed.
• Convergence and vertical handover ?
• No SIP, IMS, MIH needed
• Flat architecture
• MAC Layer
• WiFi MAC is simple
• thus cheap, but not scalable
• e.g. a single transmitting station takes up the
  entire bandwidth,
• A lot of dead time between stations
  transmissions,
• Femtocell rely on 3G standards.
• WiFi lacks subscriber manageability (e.g. TPC,
  DFS) 3G
• does have this.

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Convergence and Interworking

• The combination of femtocells and wired IP
• broadband ?
• Operators will re-use large scale elements of
  their
• current core networks such as
• billing, AAA, policy, and mobility services.
• Security and mobility gateways are needed
• To protect the integrity of operators core
  networks
• from the public environment of the Internet,
• To protect the integrity of users traffic, and
  to
• support seamless transitions between the macro
• and femtocell networks.

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FemtoCell Open Areas and Challenges

• Radio and interference issues
• Handover and mobility management
• Synchronization and localization
• QoS and Security issues

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Conclusions

• Like FMC, Femtocells are on a road to
• nowhere
• Unsatisfactory coverage and the increasing
• number of high-data-rate application are two
• driving forces for femtocell development
• Femtocells have the potential to provide
  highquality
• network access to indoor users at low
• cost
• Improve coverage
• Provide huge capacity gain