3G Femtocell
'Femtocell will revolutionalise 3G services'
Much has been said about femtocells in recent times. Frost & Sullivan senior industry analyst M Kumaresan believes that femtocells have the potential to revolutionise 3G services by enhancing user experience within an indoor environment, while serving as a major revenue proposition for mobile operators.
"Femtocells can enhance fixed-mobile substitution (FMS), enabling carriers to provide cheaper voice and data tariffs - either at flat-rates or aligned to VoIP (voice over Internet protocol) or landline tariffs - thereby encouraging users to make more calls from their mobile phones rather than their fixed-line devices at home," says Kumaresan.
Femtocells, in simple terms, are personal base stations that reside at customers' premises. Plugged into fixed-line broadband connections, these low-power radio systems provide improved cellular signal strengths within the enclosed quarters enabling faster data downloads, and allow mobile users to use their existing mobile devices to access both data and voice services.
"This is one of the key differentiators of femtocells," Kumaresan notes, "Allowing mobile users to access FMC (fixed-mobile converged) services via a single device - their existing handsets."
Mobile carriers are under immense pressure to increase ARPU (average revenue per user) by driving higher 3G data usage after having invested billions in spectrum acquisitions and network rollouts. He says, "Femtocells are a means to reduce churn and increase ARPU by increasing subscriber uptake of various and differentiated 3G data applications given that more than 90 percent of mobile data services are accessed from inside buildings.
"With fixed broadband adoption on the rise, femtocells also solve the issue of obtaining high-speed 3G signals at reduced costs by backhauling onto users' IP infrastructure, thus enabling users to enjoy next generation, high-bandwidth, data-consuming applications, such as video streaming, with a good user experience," he continues, adding that operators can also retain subscribers by locking-in contracts, bundling services with subsidised femtocell units.
While he believes that femtocells are an engineering achievement, he also says that the technology needs to juggle some operational challenges before it can realise its true potential. Kumaresan highlights that one of the major drawbacks with femtocell is the need for a fixed DSL (digital subscriber line) connection, "As most mobile operators do not own a fixed-line network, leasing network access from or partnerships with ISPs (Internet service providers) now becomes necessary."
It is a fine balance between this (leasing bandwidth) and investing in one's own fixed network. "The leasing option and cost of bandwidth, of course, now determines the business model and pricing or subsidy for femtocell units that operators are able to offer end users," he adds.
Given this, Kumaresan believes that the popularity and uptake of femtocells are likely to be more prevalent in the more mature mobile markets which also have strong fixed broadband networks, such as Hong Kong, Taiwan and Singapore. In these mature markets, however, introducing an additional node to the already complex networks will need careful planning as it has the propensity to compromise service quality if radio networks are not optimal.
The advantage of femtocell however, Kumaresan says, "Is its potential to evolve into an integrated home gateway that supports WiFi, ADSL and Ethernet, apart from cellular technology," which means that a variety of applications can be supported, enabling carriers to provide bundled triple- or quadruple-play services at lower costs.
"Some vendors are already working with carriers to provide 3G femtocells integrated with residential gateways. We believe that integrated 3G femtocells can be expected to be commercially available as early as 2010," he notes.
But for now, initial deployments are likely to be in the form of standalone 2G or 3G femtocell units. The first few deployments are likely to be seen in the more developed markets, by integrated service providers which have both wireless and fixed networks. In emerging markets, rollouts are expected to be feasible only in the commercial or business districts where data traffic is higher.
Femtocell
In telecommunications, a femtocell—originally known as an Access Point Base Station—is a small cellular base station, typically designed for use in residential or small business environments. It connects to the service provider’s network via broadband (such as DSL or cable); current designs typically support 2 to 4 active mobile phones in a residential setting. A femtocell allows service providers to extend service coverage indoors, especially where access would otherwise be limited or unavailable. The femtocell incorporates the functionality of a typical base station but extends it to allow a simpler, self contained deployment; an example is a UMTS femtocell containing a Node B, RNC and GPRS Support Node (SGSN) with Ethernet for backhaul. Although much attention is focussed on UMTS, the concept is applicable to all standards, including GSM, CDMA2000, TD-SCDMA and WiMAX solutions.
For a mobile operator, the attractions of a femtocell are improvements to both coverage and capacity, especially indoors. There may also be opportunity for new services and reduced cost. The cellular operator also benefits from the improved capacity and coverage but also can reduce both capital expenditure and operating expense.
Femtocells are an alternative way to deliver the benefits of Fixed Mobile Convergence. The distinction is that most FMC architectures require a new (dual-mode) handset which works with existing home/enterprise Wi-Fi access points, while a femtocell-based deployment will work with existing handsets but requires installation of a new access point.
The concept of a compact self-optimising home cellsite has been documented since 1999. Alcatel announced in March 1999 that they would bring to market a GSM home basestation which would be compatible with existing standard GSM phones.The high unit cost made the product unviable.
Several alternative technical solutions were developed, such as UMA which uses dual-mode WiFi/cellular handsets to achieve the same goals.
Various research projects continued to work on femtocell concept products, with Motorola engineers in Swindon claiming to have built the first complete 3G home base station in 2002.
By mid-2004 a number of companies were independently investigating femtocells (although mostly using other terms such as "residential base station" or "3G access point").
Also in 2004, two femtocell-focused companies were registered at Companies House in the United Kingdom: 3Way Networks (now part of Airvana, Inc.) and Ubiquisys. By 2005, the idea had become more widely recognised with demonstrations and conference discussion. By this stage more companies were involved, including more established suppliers Samsung, Airwalk, ip. Access and RadioFrame Networks.
By early 2007, the idea had become mainstream, with a number of major companies publicly demonstrating systems at the cellular industry 3GSM conference in February, and operators announcing trials. In July, the Femto Forum trade organisation was founded to promote femtocell deployment worldwide,[citation needed] comprising mobile operators, telecoms hardware and software vendors, content providers and start-ups. Its main work is conducted via four working groups, tackling regulatory issues, network and interoperability, radio and physical layer, and marketing and promotion.
In 3Q 2007, Sprint Nextel started a limited rollout in Denver, Indianapolis and Tennessee of a home-based UbiCell femtocell built by Samsung called the "Sprint Airave", which worked with any Sprint handset. Airave was rolled out nationwide on 17 August 2008.
As well as system manufacturers, semiconductor companies have announced chip-level products to address this application. Analog Devices has developed a chipset for the RF-IF and baseband, while picoChip claims significant commercial traction on their baseband Digital Signal Processor[citation needed]. There are significant number software stack providers for the femtocell based base stations. Continuous Computing has announced complete solution for femtocell based software stacks adhering to various femtocell based UMTS architecture described below.
To meet FCC/RA spectrum mask requirements, Access Point Base Stations must generate the RF signal with a high degree of precision, typically around 50 parts-per-billion (ppb) or better. To do this over a long period of time is a major technical challenge, since meeting this accuracy over a period longer than perhaps 12 months requires an ovenised crystal oscillator (OCXO). These oscillators are generally large and expensive, and still require calibration in the 12-to-24 month time frame. Use of lower-cost temperature-compensated oscillators (TCXO) provides accuracy over only a 6-to-18 month time frame. Both depend on a number of factors.
The solutions to this problem of maintaining accuracy are either to make the units disposable/replaceable after an 18-month period and thus keep the cost of the system low, or to use an external, accurate signal to constantly calibrate the oscillator to ensure it maintains its accuracy. This is not simple (broadband backhaul introduces issues of network jitter/wander and recovered clock accuracy), but technologies such as the IEEE 1588 time synchronisation standard may address the issue, potentially providing 100-nanosecond accuracy (standard deviation), depending on the location of the master clock. Also, Network Time Protocol (NTP) is being pursued by some developers as a possible solution to provide frequency stability. Conventional (macrocell) base stations often use GPS timing for synchronization and this could be used to calibrate the oscillator. However, for a domestic femtocell, There are concerns on cost and the difficulty of ensuring good GPS coverage.
Standards bodies have recognized the challenge of this and the implications on device cost. For example, 3GPP has relaxed the 50ppb precision to 100ppb for indoor base stations in Release 6 and has proposed a further loosening to 250ppb for "Home NodeB" in Release 8.
'Femtocell will revolutionalise 3G services'
Much has been said about femtocells in recent times. Frost & Sullivan senior industry analyst M Kumaresan believes that femtocells have the potential to revolutionise 3G services by enhancing user experience within an indoor environment, while serving as a major revenue proposition for mobile operators.
"Femtocells can enhance fixed-mobile substitution (FMS), enabling carriers to provide cheaper voice and data tariffs - either at flat-rates or aligned to VoIP (voice over Internet protocol) or landline tariffs - thereby encouraging users to make more calls from their mobile phones rather than their fixed-line devices at home," says Kumaresan.
Femtocells, in simple terms, are personal base stations that reside at customers' premises. Plugged into fixed-line broadband connections, these low-power radio systems provide improved cellular signal strengths within the enclosed quarters enabling faster data downloads, and allow mobile users to use their existing mobile devices to access both data and voice services.
"This is one of the key differentiators of femtocells," Kumaresan notes, "Allowing mobile users to access FMC (fixed-mobile converged) services via a single device - their existing handsets."
Mobile carriers are under immense pressure to increase ARPU (average revenue per user) by driving higher 3G data usage after having invested billions in spectrum acquisitions and network rollouts. He says, "Femtocells are a means to reduce churn and increase ARPU by increasing subscriber uptake of various and differentiated 3G data applications given that more than 90 percent of mobile data services are accessed from inside buildings.
"With fixed broadband adoption on the rise, femtocells also solve the issue of obtaining high-speed 3G signals at reduced costs by backhauling onto users' IP infrastructure, thus enabling users to enjoy next generation, high-bandwidth, data-consuming applications, such as video streaming, with a good user experience," he continues, adding that operators can also retain subscribers by locking-in contracts, bundling services with subsidised femtocell units.
While he believes that femtocells are an engineering achievement, he also says that the technology needs to juggle some operational challenges before it can realise its true potential. Kumaresan highlights that one of the major drawbacks with femtocell is the need for a fixed DSL (digital subscriber line) connection, "As most mobile operators do not own a fixed-line network, leasing network access from or partnerships with ISPs (Internet service providers) now becomes necessary."
It is a fine balance between this (leasing bandwidth) and investing in one's own fixed network. "The leasing option and cost of bandwidth, of course, now determines the business model and pricing or subsidy for femtocell units that operators are able to offer end users," he adds.
Given this, Kumaresan believes that the popularity and uptake of femtocells are likely to be more prevalent in the more mature mobile markets which also have strong fixed broadband networks, such as Hong Kong, Taiwan and Singapore. In these mature markets, however, introducing an additional node to the already complex networks will need careful planning as it has the propensity to compromise service quality if radio networks are not optimal.
The advantage of femtocell however, Kumaresan says, "Is its potential to evolve into an integrated home gateway that supports WiFi, ADSL and Ethernet, apart from cellular technology," which means that a variety of applications can be supported, enabling carriers to provide bundled triple- or quadruple-play services at lower costs.
"Some vendors are already working with carriers to provide 3G femtocells integrated with residential gateways. We believe that integrated 3G femtocells can be expected to be commercially available as early as 2010," he notes.
But for now, initial deployments are likely to be in the form of standalone 2G or 3G femtocell units. The first few deployments are likely to be seen in the more developed markets, by integrated service providers which have both wireless and fixed networks. In emerging markets, rollouts are expected to be feasible only in the commercial or business districts where data traffic is higher.
Femtocell
In telecommunications, a femtocell—originally known as an Access Point Base Station—is a small cellular base station, typically designed for use in residential or small business environments. It connects to the service provider’s network via broadband (such as DSL or cable); current designs typically support 2 to 4 active mobile phones in a residential setting. A femtocell allows service providers to extend service coverage indoors, especially where access would otherwise be limited or unavailable. The femtocell incorporates the functionality of a typical base station but extends it to allow a simpler, self contained deployment; an example is a UMTS femtocell containing a Node B, RNC and GPRS Support Node (SGSN) with Ethernet for backhaul. Although much attention is focussed on UMTS, the concept is applicable to all standards, including GSM, CDMA2000, TD-SCDMA and WiMAX solutions.
For a mobile operator, the attractions of a femtocell are improvements to both coverage and capacity, especially indoors. There may also be opportunity for new services and reduced cost. The cellular operator also benefits from the improved capacity and coverage but also can reduce both capital expenditure and operating expense.
Femtocells are an alternative way to deliver the benefits of Fixed Mobile Convergence. The distinction is that most FMC architectures require a new (dual-mode) handset which works with existing home/enterprise Wi-Fi access points, while a femtocell-based deployment will work with existing handsets but requires installation of a new access point.
The concept of a compact self-optimising home cellsite has been documented since 1999. Alcatel announced in March 1999 that they would bring to market a GSM home basestation which would be compatible with existing standard GSM phones.The high unit cost made the product unviable.
Several alternative technical solutions were developed, such as UMA which uses dual-mode WiFi/cellular handsets to achieve the same goals.
Various research projects continued to work on femtocell concept products, with Motorola engineers in Swindon claiming to have built the first complete 3G home base station in 2002.
By mid-2004 a number of companies were independently investigating femtocells (although mostly using other terms such as "residential base station" or "3G access point").
Also in 2004, two femtocell-focused companies were registered at Companies House in the United Kingdom: 3Way Networks (now part of Airvana, Inc.) and Ubiquisys. By 2005, the idea had become more widely recognised with demonstrations and conference discussion. By this stage more companies were involved, including more established suppliers Samsung, Airwalk, ip. Access and RadioFrame Networks.
By early 2007, the idea had become mainstream, with a number of major companies publicly demonstrating systems at the cellular industry 3GSM conference in February, and operators announcing trials. In July, the Femto Forum trade organisation was founded to promote femtocell deployment worldwide,[citation needed] comprising mobile operators, telecoms hardware and software vendors, content providers and start-ups. Its main work is conducted via four working groups, tackling regulatory issues, network and interoperability, radio and physical layer, and marketing and promotion.
In 3Q 2007, Sprint Nextel started a limited rollout in Denver, Indianapolis and Tennessee of a home-based UbiCell femtocell built by Samsung called the "Sprint Airave", which worked with any Sprint handset. Airave was rolled out nationwide on 17 August 2008.
As well as system manufacturers, semiconductor companies have announced chip-level products to address this application. Analog Devices has developed a chipset for the RF-IF and baseband, while picoChip claims significant commercial traction on their baseband Digital Signal Processor[citation needed]. There are significant number software stack providers for the femtocell based base stations. Continuous Computing has announced complete solution for femtocell based software stacks adhering to various femtocell based UMTS architecture described below.
To meet FCC/RA spectrum mask requirements, Access Point Base Stations must generate the RF signal with a high degree of precision, typically around 50 parts-per-billion (ppb) or better. To do this over a long period of time is a major technical challenge, since meeting this accuracy over a period longer than perhaps 12 months requires an ovenised crystal oscillator (OCXO). These oscillators are generally large and expensive, and still require calibration in the 12-to-24 month time frame. Use of lower-cost temperature-compensated oscillators (TCXO) provides accuracy over only a 6-to-18 month time frame. Both depend on a number of factors.
The solutions to this problem of maintaining accuracy are either to make the units disposable/replaceable after an 18-month period and thus keep the cost of the system low, or to use an external, accurate signal to constantly calibrate the oscillator to ensure it maintains its accuracy. This is not simple (broadband backhaul introduces issues of network jitter/wander and recovered clock accuracy), but technologies such as the IEEE 1588 time synchronisation standard may address the issue, potentially providing 100-nanosecond accuracy (standard deviation), depending on the location of the master clock. Also, Network Time Protocol (NTP) is being pursued by some developers as a possible solution to provide frequency stability. Conventional (macrocell) base stations often use GPS timing for synchronization and this could be used to calibrate the oscillator. However, for a domestic femtocell, There are concerns on cost and the difficulty of ensuring good GPS coverage.
Standards bodies have recognized the challenge of this and the implications on device cost. For example, 3GPP has relaxed the 50ppb precision to 100ppb for indoor base stations in Release 6 and has proposed a further loosening to 250ppb for "Home NodeB" in Release 8.
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