Femtocell Hardware Components

• An RF Front-End connects to the antenna and converts the digital signals to and from radio transmissions
• Baseband processing which analyse and decode the complex transmissions into meaningful data
• Control processing which runs the software to communicate with handsets and the femtocell gateway.

These chips would be supported by separate memory chips, typically a read/write chip for transient data (called RAM) and a read only chip which holds the program (called ROM). These are standard components used in many electronic devices.

A critical component is the crystal frequency oscillator which provides a very accurate clock, important for synchronising the timing of signals to handsets. Rakon are leading the supply of low cost oscillators for femtocells.

There is a tradeoff for femtocell designers between availability and flexibility of the hardware chips used and their cost. Some femtocells have been developed using standard DSP chips which are immediately available in quantity, but at a price. Other manufacturers are developing femtocell specific "System on a Chip" devices which will be much cheaper when bought in large volumes, and will also use much lower power in operation.

The main suppliers of these chipsets include:

• picoChip where their PC2xx range has been used for many HSPA, LTE or TD-SCDMA designs. Their more recent PC3xx range has been optimised for HSPA femtocells. They have dominated the initial market for femtocell designs.
• Texas Instruments (TI) who have supplied their DSP solution without any modification. This leads to a higher power design than those with dedicated chips.
• Percello who have developed high performance chipsets only for the femtocell market, already capable of up to 21 Mbit/s data or 16 voice calls.
• Qualcomm who have announced their market entry, with first samples likely during 2H 2010.
• RadioFrame have also developed a femtocell specific chip. It is not publicly known which femtocell vendors are using it.

• ADI
• Maxim
• Lime

Middleware

Application Software

• 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

Packaging

It's often said you shouldn't judge a book by its cover..... but of course many people do. Some femtocells are decidedly nicer looking than others, and have even been incorporated with other features such as digital picture frames. This is perhaps an easier way to impress the end customer, with a variety of operating branding also being an option. Motorola has gained a lot of publicity for their range of more unusual designs.

The other aspect of packaging involves incorporating the femtocell within a more general home gateway. Many femtocell vendors have provided their products as modules which are fitted into broadband modems, alongside a router, Wi-Fi and even IPTV. Some analysts predict that this may well be the format that as many as 90% of femtocells would be delivered in a few years time. Vendors with integrated products include NetGear, Pirelli, Thomson and 2Wire.

Read on to find out who makes femtocells

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