Managing cost issues in the design of femtocell home base stations, Part 1

Semiconductor vendors and original design manufacturers (ODMs) are stepping up to meet these requirements for the cellular equipment vendors in various ways. High levels of component and functional integration, packaging options, design for manufacturing and scaleable digital signal processing (DSP) performance can ensure that femtocell metrics are met.

This article will explore the short- and long-term configuration and architectural options that will allow designers to hit the right performance metrics at a bill of materials (BOM) cost that will enable the deployment of millions of units. Designers also need to think carefully about ensuring that their system is sufficiently flexible to meet future demands.

The semiconductor vendor perspective
From a semiconductor-vendor perspective, the femtocell today takes on the performance and reliability of a macro base station, while adopting the costs, ease-of-use, and flexibility of a handset. This scenario begs a number of questions: What kind of radio is needed to meet the industry's current- and future needs? What are its performance metrics? Does it need to meet the performance levels that are being requested by multiple operators today? Does the baseband solution need to be specified in a way that carries the femtocell through several years of upgrades and cost reductions? In the absence of a specific standard for femtocells, operators are driving the performance specification based on picocell and other higher order, more complex base-station systems.

The value propositions appear to be well-defined, but the functional requirements and specifications are not. The expectations of performance may be out of line with expectations of cost. In the absence of a formal femtocell specification, all members of the value chain should align realistic expectations of performance and cost, in order to allow semiconductor manufacturers to translate their system needs into silicon solutions. Otherwise, performance expectations may be out of step with costs.

Femtocell concept field trials, in addition to efforts by the Femtocell Forum, should help codify the specification requirements. This will help to align market expectations and costs to stimulate a new round of semiconductor investments in chipsets, which, in turn, can result in further cost reductions.

Market Expectations and Requirements
What are the expectations and requirements for femtocell functionality today? Figure 1 shows some of the ecosystem challenges placed on the home base station market from a semiconductor view.