Femtocells Asia 2008, Asia’s very first international conference on femtocells organised by the UK-based Avren Events kicked off in the Shangri-La Hotel in Kuala Lumpur on 22 September.

It was attended by 150 delegates, a quarter of whom represented operators, mostly from Asia, with the rest from Europe and the United States.

While Avren’s previous Femtocells events held in Europe and the United States were attended by 250 delegates, Avren’s marketing director Carole Mayhew expects more delegates to attend its next Femtocells Asia event next year.

“We see femtocells as a growing technology and our Femtocells events are a natural extension of our Basestation Conference,” said Mayhew.

Founded in 2003, Avren held its inaugural Femtocells event in Europe last year, which also was the world’s first femtocells event. 

It’s held three more Femtocells events -- one in Europe and two in the United States – with Femtocells Asia 2008 being its fifth.

But what are femtocells?

Roughly the size of an off-the-shelf WiFi access point/router, femtocells essentially are very small footprint mobile base stations which use wide-area network radio access technologies, such as GSM, UMTS, CDMA 2000 or WiMAX to serve the voice, data and potentially video needs of four to eight users, much like microcells and picocells do inside buildings, especially where signals from regular wide-area cells, known as macrocells, can’t reach.

Motorola engineers are credited with having developed a the first prototype femtocell in 2002 and they’ve come a long way since then.

For example, Japanese operator Softbank Mobile's chief technology officer (CTO), Junichi Miyakawa announced at Femtocells Asia 2008 that the company would be implementing a soft launch of 1,000 Femtocell access points in October 2008 with mass deployment plans for Jan 2009.

This would make Softbank Mobile Asia’s first operator and perhaps the world’s first to launch service using femtocells. In his keynote addres Miyakawa gave a detailed overview of their network and how it will support IMS (IP Multimedia Subsystem) Femtocells, with the promise of innovative new services for their consumers.

“We’re thrilled to hear the announcement of the first commercial rollout of 3G Femtocells and are privileged to be a part of it” said Ubiquisys CTO, Will Franks speaking from Avren’s Kuala Lumpur event.

Besides Japan, there's leading interest in femtocells in Europe and Taiwan, while trials are being conducted in Malaysia.

Since femtocells are usually attached to fixed broadband digital subscriber line (xDSL), cable or Ethernet connections in premises, they enable operators to provide in-premises cellular voice and data services without putting additional demand on operators’ macrocell networks, which has attracted much interest in them among mobile operators worldwide, including in Malaysia.

"For example, a femtocell can stream video or IP TV directly from the Internet to a mobile phone or other viewing device bypassing the mobile network, while the femtocell only sends a record of the viewing to the operator over the cellular network if required for billing or other purposes," said David Swift, senior marketing manager with Alcatel-Lucent, one of the event's gold sponsors.

Service providers can focus on managing their quality-of-service (QoS) and can also assign dedicated backhaul capacity to handsets,thus lowering latency (delays) and enabling faster response times. Femtocells also let mobile phones reduce their signal power, thus conserving battery life.

In vast countries, such as the United States and Canada, with high fixed line penetration of around 90%, femtocells enable cellular operators to provide service in remote areas beyond their macrocell coverage.

Also, houses in temperate regions use metalised glass windows to keep the heat in but this blocks radio signals, so femtocells are needed to provide service indoors and likewise where metalised glass windows are used to keep the heat out in tropical regions.

Femtocells have also created lucrative opportunities for upstream processor chip and software suppliers, simulator and test instrumentation manufacturers, as well as others.

Comm & Tech Asia spoke to some of them at Femtocells Asia.

Zero touch femtos

While femtocells have caught the attention of the market, there still are some issues, especially related to standardisation and configurability which have to resolved, according to Jean-Paul Rissen, Alcatel-Lucent director of wireless technologies.

Users of mobile phones, especially in Malaysia, are only too familiar with having to configure their phone’s MMS, WAP, GPRS, 3G and other mobile data settings before they can enjoy these services; and with femtocells being deployed in the millions, they will have to be able to configure themselves automatically with the service provider’s network with no user intervention at all, or what the industry terms “zero touch.”

Most femtocells today are designed to be connected to the DSL or cable TV connection in homes or offices, with big US cable company, Comcast planning to attach, WiMAX, CDMA and UMTS  femtocells to their cable points in premises.

Also unlike macrocells, which trained professionals install, commission and plan their radio frequencies; it would be too expensive and impractical for the experts do the same for the millions of femtocells deployed.

So femtocells must be self-organising and self-optimising and be able to detect the frequencies of ambient signals from macrocell base stations in the vicinity and from neighbouring femtocells and adjust their signal frequencies or group of scrambler codes in the case of CDMA, so as not to interfere with them, and Alcatel-Lucent is has been developing this self-organising capability for some years already. They must also have in-built network security.

Also, typical femtocells today are similar to WiFi routers in providing coverage of homes and offices and have typically have a range of  50 metres in clear line of sight but their coverage could be drastically reduced or even blocked, especially in apartments or offices with concrete walls, ceiling and floor.

“However, second generation femtocells being looked into will have beam forming capabilities to optimise coverage, while use of the home’s electrical wiring to support repeaters in different rooms is also being looked into,” said David Swift.

Applications and services

Technical issues aside, as with any other technology-based platform, applications and value-added services are required to drive femtocell uptake.

“For example, a simple application could automatically turn on the lights in a home as an occupant approaches,” said Swift.

The application would know the occupant is nearby based on location information provided by the network.

A more elaborate application could automatically synchronise photos, music, videos and other content on an occupant’s mobile phone with the home PC, Playstation, Xbox or other such device and since the data traffic is purely local, it does not load the operator’s network, incurs no data charges.

“A mix of surveys across the United States, Europe, Taiwan, Singapore and Australasia commissioned by Alcatel-Lucent show that people are willing to pay a few dollars more for a valuable service,” said Swift.

For example, studies of mobile TV viewing found that half the respondents watched mobile TV at home, especially since like personal music players, it lets each family member watch their favourite programme without having to fight over which programme to watch on their living room TV and it also lets them watch replays of TV programes they’ve missed, and femtocells will enable them to do all these without taxing network resources.
 
Alcatel-Lucent is also looking into triple-play and quadruple-play services which operators could provide, especially since they currently have a small share of this cake.

“We recommend operators offer femtocells as part of an applications and services package, so they can manage the quality of service,” said Swift.

Femtocells also provides opportunities for mobile and fixed network operators to collaborate, especially since they require a broadband connection, which in countries such as Malaysia, is mostly provided via a fixed DSL connection operated by Telekom Malaysia and this enables operators to reverse falling demand for fixed lines, as more people use mobile phones for voice calls.

One wonders whether since femtocells are so small portable, people would take them overseas to save on international roaming charges.

“Using femtocells intended for one country in another could violate licensing regulations and could also cut into operator revues there, so Alcatel-Lucent has designed our femtocells to not work if they detect they are on a different IP address,” said Swift.

End-to-end solution

Bronze sponsor Ericsson offers its Femtocell end-to-end solutions, comprising its GSM Home Access Point R1, Femto BSC (base station controller) and related supporting nodes such as its security gateway, domain name (DNS) & authentication, authorisation and accounting (AAA) server, auto-configuration server (ACS) and related supporting nodes. The ACS provides software management for the home gateway.

Ericsson envisages its solution lets operators charge lower call rates for calls made while at home.

About the size of a typical LAN router, the home gateway connects to the Internet via an ADSL 1, 2 or 2+ connection, or a 10/100 Base-T Ethernet connection and connects to PCs indoors via three LAN ports or WiFi 802.11g and it supports two simultaneous mobile phones calls over its two internal 1,800MHz GSM time-slots.

A key feature of the home gateway -- which has its own SIM -- is its automatic handoff capability between GSM 900MHz or GSM 1,800 MHz macrocell and itself and vice-versa, as the user enters or leaves the premises.

The home gateway is based on Ericsson’s mobile platform chipset for economies of scale, since about 90% of mobile phones worldwide are GSM-enabled.

It communicates with and terminates on the security gateway through the Internet cloud and the gateway in turn is connected to the ACS, Femto BSC and DNS & AAA server and supports network-address translation (NAT) for VPN (virtual private network) pass-through, IPSec (IP security) tunnel termination for GSM and O&M traffic, IKEv2 (Internet key exchange) support and the Extensible Authentication Protocol Method for GSM Subscriber Identity (EAP-SIM) for device authentication.

Number one

The UK-based Ubiquisys, which exhibited at the event was ranked first among 10 companies examined in terms of innovation and implementation in ABI Research’s Femtocell Equipment Vendor Matrix.

Ubiquisys scored 62 and 64 points respectively for those two scores and its ranking was calculated based on the root mean square of the above two scores.

According to ABI, investors in the privately owned company founded in 2004 include Google and T-Mobile Venture Fund and Ubiquisys’ ZoneGate femtocells use either RAN (radio access network) Gateway or IMS (SIP) based protocols for connection to mobile operators’ networks.

ZoneGate supports up to 7.2Mbps HSPA (high-speed packet access) downlink data rates, up to four simultaneous voice or data users and all signaling and voice traffic is IPSec (IP security) encrypted, multiplexed and prioritized.

“Ubiquisys femtocells have an adaptive radio which senses macro base stations and neighbouring femtocells and intelligently adapts its signal, for example by using an available  group of scrambling codes in the case of CDMA, to minimise its interference with the others,” said Len Schuch, Ubiquisys founder and vice-president.

For the backhaul connection, ZoneGate can use fibre, ADSL, WiMAX and others.
 
Silicon for femtocells

Many communication devices these days are based on software defined radio (SDR) and femtocells are no different.

With SDR, the signal processing is performed by a general purpose processor controlled by embedded software, rather than purpose-built hardware, with only the radio frequency front end being implemented in hardware.

The advantage of SDR, as with any software driven device, is that the device can be made to operate according to different communication protocols simply by changing the software.

The UK-based picoChip Designs produces a range of single-chip solutions, hardware platforms and software reference designs for downstream Wideband-CDMA, TD-SCDMA (Time Division – Synchronous CDMA), WiMAX access point and femtocell manufacturers, including Alcatel-Lucent, ip.access and Ubiquisys.

For example, its PC202 is a consumer-oriented single-chip solution combining its picoArray multi-core digital signal processor (DSP) with integrated ARM926 processor used for example in Wideband-CDMA/HSPA and TD-SCDMA femtocells, while the high-performance PC205 is used in WiMAX and 3G LTE (3G Long Term Evolution) infrastructure equipment, mesh-nodes, femtocells and other equipment.

On display were sample circuit boards for WiMAX, TD-SCDMA and WCDMA/HSPA femtocells using picoChip solutions.

GPS indoors

US-based SigNav specialises in developing integrated, multi-function silicon solutions for network synchronization, frequency reference and geographic positioning for femtocells and WiMax infrastructure equipment.

Its products include the subATTOmIC S100 GPS timing receiver IC, uTevo weak signal clocking receiver micro module, TM1, TM2 and TM3 series assisted GPS timing modules and an evaluation kit.

These chips and micro-modules which are embedded in femtocells are able to receive weak GPS signals indoors, which its president Brad Anderson claimed are 32 times more sensitive than competing receivers.

Only the acquisition of a single GPS satellite is sufficient for data extraction and timing, while acquisition of four is required to determine position.

Timing and syncronisation information are required for handoff of mobile phones between the femtocell and the public macrocell, while many operators want to know where the femtocell is in case the user tries to operate it in another country, where it not only will result in depriving operators revenue from roaming charges but more seriously could interfere with cellular there.

Also, emergency services in many countries are dispatched based on the location of the call.

The S100 chip and the modules also produce very low phase noise frequency which can be used as the femtocell’s system clock, thus saving manufactures from having to install a dedicated clock chip which typically costs from US$50 to US$60 each.

“Carriers have also realised that synchronization of networks using the IEEE1588 Precise Time Protocol involves regular pinging in real-time which consumes network capacity on high-priority channels but SigNav technology only requires a few data bits by transferred at low priority every four hours,” said Anderson.

A satellite’s position in the sky varies over time, so the operator needs to send clock and orbital correction data to the femtocell to enable to acquire satellites.

Zero mask ASIC

ASICs or application-specific integrated circuits are designed in silicon for specific use in a particular piece of electronic equipment, such as a cellphone or a femtocell and constructing them in silicon typically requires  a set of about 40 masks (like stencils) costing about US$1 million or more per set.

Since the femtocell market is still very new, such cost and numbers are prohibitive for their developers.

However, US-based eASIC Corporation’s Nextreme New ASICs make it very affordable for developers by combining an FPGA (field programmable gate array) –like logic cell, called an eCell with single via customisable routing.

The term “via” here refers to the metal contacts which connect together the different parts of copper tracks on multi-layer electronic circuit boards or the different layers in a silicon chip.

An FPGA is a single semiconductor device containing programmable components called “logic blocks” and programmable interconnects, The logic blocks can be programmed to perform the functions of simple AND, OR, NOT, NAND, NOR or XOR logic gates, as well as more complex combinational logic functions as in decoders and the arithmetic logic units in microprocessors.

In 1960s and 70s, small-scale integration chips contained a handful of logic gates per integrated circuit. For example, Texas Instrument’s 14-pin, 7400N TTL (Transistor Transistor Logic) IC contained four, dual-input NAND gates.

The logic blocks in most FPGAs also include simple memory elements which may be simple flip-flop circuits or complete blocks of memory.

In 1968, RCA introduced the 4000 series of ICs based on the Complementary Metal Oxide Semiconductor (CMOS) technology, which consumed less power and worked with a much wider range of supply voltages ranging from 3 to 15 volts, versus the 7400’s 5 volts but was initially slower than TTL.

The small number of logic gates and elements contained in these early ICs resulted in many having to be used to construct a circuit, leading to circuit boards looking like an aerial view of a housing estate, such as with those used in the first IBM PC and quite often, each piece of electronic equipment contained several circuit boards.

However, advances in large scale integration (LSI) since then have put most of the gates and other logic circuitry onto a single large chip, leading to the typical board scenario today, where there’s usually one large chip, with a few peripheral components on a small board, leaving much vacant space inside the piece of equipment. 

While FPGA technology has contributed significantly to this high level of logic integration, still traditional, 20-year old FPGA technology requires transistors and SRAM cells, both of which consume space on the chip and power, even when not in use.

On the other hand, eASIC’s patented technology used in Netextreme saves cost by having a common set of layers, except the last – a single via layer, is customised by writing directly onto the  wafer using a direct write-electron beam (eBeam) without requiring an expensive mask, thus resulting in power consumption and unit cost comparable to cell-based ASICs.

“So instead of paying millions, developers pay next to nothing,” said Jasbinder Bhoot, eASIC senior director for Worldwide Marketing.

There’s also no minimum order quantity, so developers can order as few as one chip or several chips performing different functions all built on the same semiconductor wafer which is ideal for when prototyping, while the minimum production run for traditional technology is about 30,000 units.

eASIC’s technology also lets orders from several customers to be built on the same wafer, thus further reducing cost.

Netextreme comes in two optionss – namely Netextreme SL and Netextreme VL, both of which use via-customised routing.

With Netextreme SL, the look-up-table configuration is implemented by loading a bit-stream into SRAM. This method provides the fast turnaround time and flexibility and is ideal when producing prototypes.

Netextreme VL hard-wires the look-up table and dispenses with using the SRAM, which while not having the flexibility of SRAM-based FPGAs but is instant on, has no high in-rush current and is less susceptible to soft errors.

Software

Founded in 2006 by a group of scientists in Europe involved in MIMO (Multiple Input, Multiple Output) antenna technology, Germany-based mimoOn provides the software which runs on DSP platforms to handle the 3GPP LTE terminal physical (PHY) and medium access control (MAC) layers, 3GPP LTE PHY and MAC software on a picoArray and the 3GPP LTE base station protocol stack.

“mimoOn has been developing the reference code for LTE over the past two years and we are now working with hardware platform vendors to port the code to their platforms and optimise them for performance, power consumption and cost,” said Willem Mulder, mimoOn vice-president for Standards & IP.

For example, the first femtocells from Sprint had a street price between US$200 and US$250 but more recently the street price had to be below US$100 to meet Vodaphone’s target.

Moreover, the bill of materials cost has to be around 30% of the street price, so the ported software requires a powerful hardware platform at the right cost level.

While ASICs are cheaper and consume less power, prices of powerful processors have since dropped sufficiently, so it’s cheaper to implement functions in software.

mimoOn focuses on LTE, since that’s the next generation technology in the 3GPP roadmap, instead of competing in the arena with established technologies and it aims to lead in the LTE space.

On 3G versus WiMAX Mulder said, “So far, Wideband-CDMA has not had large volume but now with data cards and the iPhone taking off, there’s a business case for Wideband-CDMA and its later evolutions.”

“On the other hand, while WiMAX has strong backing from Intel, Samsung and Sprint Nextel; its big challenge is to create economies of scale comparable to cellular and to reduce the cost of its technology.

“While WiMAX is certainly ahead of LTE for now, it needs to grow or it will be overwhelmed by LTE,” Mulder added.

Security

Historically, telecommunications equipment are installed in locations off-limits, except to authorised personnel but the impending proliferation of femtocells, with their IP-based traffic in the hands of almost anyone exposes networks to security risks similar to those created by the earlier proliferation of millions of PCs on Internet.

“With the proliferation of tens of thousands of access points, there’s a need for IP Security to for authentication, integrity and encryption of traffic as it travels from the femtocell over the public Internet to the operator’s core network,” said said Rasa Siegberg, technical product manager with SFNT Finland, SafeNet’s Finland unit.

The US-based SafeNet provides embedded hardware and software security solutions, such as its SafeXcel IP Packet Engine and QuickSec/IP toolkit for integration of security features into femtocells and the next-generation chips they require.

SafeNet’s award-winning IPsec security systems are deployed by leading global telecommunications, networking, wireless, and semiconductor vendors, including companies such as AMCC, AMD, Cisco Systems, Hitachi, HP, Juniper Networks, PMC-Sierra, Lucent Technologies, NEC, Nortel, Siemens, Samsung, and Texas Instruments and it provides security solutions for all types of computing and communications.

For example, its IKE Version 2 (Internet key exchange) solution provides the exchange keys for encryption, while it also provides crypto algorithms integrated into access points to minimise the load on its main processor.

Test & measurement tools

Femtocells, mobile phones, macro base stations and core networks will require tools for engineers and technicians to monitor and test their performance and two such equipment supplies, namely Rohde & Schwarz and Tektronix exhibited at the event.

Femtocell developers will need to test their prototypes’ operation with the cellular network core but few operators would be willing to let them do so on their live network, should any bug adversely affect their network’s operation, so the US-based Tektronix offers developers their G35 3G core network emulator which lets developers test their prototype femtocells, generic access networks (GANS – ie. wireless LAN) or UTRAN (UMTS Terrestrial Access Network) base stations.

“The G35 simulates the functions of the big switches in networks in their labs and Tektronix provides Iu-CS and Iu-PC interfaces connecting femtocells to the core network,” said Che Yong Feng, Tektronix senior account manager for Network Diagnosis Product.
 
In UMTS networks, the Iu-CS interface connects the links the radio network controller (RNC) with the 3G mobile switching centre (MSC), while Iu-PS connects the RNC to the 3G SGSN (3G servings GPRS support node).
 
The G35 lets them conduct test the end-to-end system testing of these prototype equipment or to demonstrate their capabilities to customers or at trade fairs.

It automatically handles all circuit-switched voice and video call setup and release from actual mobile terminals and it supports several standard audio and video codecs.

It also SMS traffic from and to mobile phones and between phones, simultaneously handles both circuit-switched call over the Iu-CS interface and packet-switched sessions over the lu-PS interface and it also supports Iu-CS and Iu-PS over ATM or IP networks.

Tektronix G35 customers include Alcatel-Lucent, ip.access and NEC and its price varies between US$180,000 to US$300,000 based in the number of cards installed and protocols being tested.

Germany-based Rohde & Schwarz provides a range of test and measurement equipment, including signal generators and analysers for many for many wireless standards, such as LTE, HSDPA and WiMAX and the company highlighted its Rohde & Schwarz FSV touchscreen signal analyser which it claims is five times faster than the competition.

It reads up to 28MHz signal analysis bandwidth standard, with an option for 40MHz which Rohde & Schwarz claims is unmatched in its class.

The FSV has a frequency range up to 3.6GHz/7GHz, a 0.4 dB level measurement uncertainty up to 7 GHz, analysis software for GSM/EDGE, WCDMA/HSPA, LTE, WiMAX, WiLAN and analogue modulation methods.

It supports power sensors from Rohde & Schwarz NRP family together with extensive power measurement functions.

“The FSV can analyse signals in the air via an antenna, including signals from bases stations or from mobile phones and it can be configured to address only wanted signals,” said Rohde & Schwarz, Test & Measurement Products area manager Hagen Heggenberger.

Meanwhile, the Rohde & Schwarz TSMW Universal Radio Network Analyser is a scanner with a high dynamic range for WiMAX measurements and I/Q receiver for custom-specific applications.

It displays these readings as coloured graphs and charts onscreen and records raw I/Q in real time with data access via a MATLAB or C++ interface, enabling the results to be processed on a PC.

MATLAB lets engineers design and analyse receiver algorithms and it can be ported to C++ as a real-time version.

The TSMW lets network engineers check for neighbouring WiMAX cell sites, unknown WiMAX carrier frequencies in the area and for gaps in coverage where a base station or repeater could be installed. Its two radio-frequency ports have a user-definable range between 30MHz and 6 GHz.  

It works with Rohde & Schwarz ROMES test drive software running on a laptop, enabling field engineers to analyse interference of GSM and WCDMA signals, handoff between cells, performs key performance indicator (KPI) calculations, HSDPA and HSUPA measurements, GSM base station position estimation benchmarking and so on and displays the results, including on a map on the notebook screen.

Rohde & Schwarz FSH family of handheld spectrum analysers are used by installation, commissioning and maintenance engineers for a wide range of frequency, power, field-strength and other measurements in the field up to a 18GHz signal frequency, depending on model.

It displays these readings on its TFT colour display. It also works with Rohde & Schwarz Windows-based View Control software provided with every FSH analyser.