picoChip announced a new chip and reference design this week which sets the bar for LTE femtocells and could determine the path by which the mobile industry rolls out its 4G networks. We spoke with Doug Pulley, the picoChip CTO to understand where they’re coming from, and uncovered a dual-mode 3G/4G chipset in the works.

Dual Mode 3G/4G femtocells are a key market requirement

Users won’t want two femtocell boxes in their home. As 3G was rolled out around the world, almost all phones and devices were 2G and 3G dual mode capable. This meant it was transparent for the end user whether they were actively using one or other system, although data performance was obviously much improved on 3G.

Dual Mode 3G/4G chipset launched

picoChip have a dual-mode HSPA+/LTE device (internal codename "Feynman ") on a single chip suitable for domestic and public femtocell use.

• Supports simultaneous calls on 3G and 4G
• Includes their recently touted “sniffer” capability to monitor 2G, 3G and 4G signals in the neighbourhood
• Supports both LTE FDD and TDD modes.

Based on existing proven platform

The chipset is similar to their PC302 System-on-a-chip announced earlier as a low cost 3G femtocell. As with all picoChip solutions, it amalgamates hundreds of processing cores combining both the heavy-lifting baseband signal processing with the associated signalling control and management.

The Feynman chip has to be a lot more powerful than 3G solutions. LTE is designed to handle much higher data rates, spectrum bandwidth of up to 20Mbit/s.

LTE standard incorporates Femtocells from day one

LTE was designed to include femtocells from an early stage, rather than having them retro-fitted at a later stage as happened with HSPA. This includes the concept of Self Organising Networks (SON), so that the system automatically adapts to reduce interference. Each cell detects its neighbours.

picoChip themselves have put a lot of effort into modelling the LTE radio environment. Doug stated they and their partners have around 35 people working full time on LTE chips and software today.

Femtocell Chipset Pricing

Doug Pulley believes that today’s 3G HSPA femtocells have a BoM (Bill of Materials) cost of around $60-70 (in high volumes). Product cost is around double that. It’s working its way down to the $50 target that would enable end-user fully built products to achieve the $100 price point.
LTE femtocells will be more expensive than 3G HSPA:

• HSPA handles a single 5MHz carrier and a single antenna
• LTE supports 20MHz bandwidth with multiple antenna using MIMO

The initial BoM for LTE only chipsets should be around $100, with the BoM for residential dual-mode HSPA+/LTE dropping to $70 by 2011.

You can read more about Doug Pulley's thoughts on femtocells more generally in our recent femtocell leadership interview

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