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Femtocell Definition • A small cellular base station, designed for use in residential or enterprise. • Connects to the service provider’s network via broadband. • Support 2 to 5 mobile. • Allows service providers to extend service coverage indoors.
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.
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.
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.
Architectures Home Node B (HNB/HeNB): • In 3GPP terms, LTE femto-cells are called Home Node B’s for HSPA and Home eNode B’s 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.
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.
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
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
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.
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.
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.
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.
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
Deployment • Irregular deployment will incur inevitable interference
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).
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.
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.
FemtoCell Open Areas and Challenges • Radio and interference issues • Handover and mobility management • Synchronization and localization • QoS and Security issues
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