Understand receiver dynamics and AGC tradeoffs in WiMAX femto- and picocells By Manish Manglani, Tony Montalvo and Chris Cloninger EE Times September 29, 2008 (03:01 PM EST)   WiMAX deployment is increasing due to the allocation of additional frequency spectrum and the need for higher data rates and broadband access around the globe. Because WiMAX is designed to be a data-centric standard, its infrastructure deployment must be different from previous voice-centric standards such as GSM and CDMA. WiMAX, operators will continue to deploy conventional macrocells, which are intended to provide initial coverage and capacity, but will rely more on smaller base stations to fill gaps in coverage and add needed capacity in densely populated areas like large cities. These smaller base stations, sometimes called microcells or picocells, are typically operator-installed equipment. Femtocells and picocells are ideally the size of a WLAN access point (20 cm x 15 cm x 5 cm = 1500 cm3), so they can be mounted easily on walls of buildings, on top of lightposts or in tunnels. They have limited power budgets (they're often powered over Ethernet) and must achieve excellent performance, as this will enhance the customer's experience while minimizing capital expense requirements. In addition to deploying macrocells, microcells, and picocells, some operators are investigating consumer-purchased and -installed femtocells to improve coverage in a home or small office. When a WiMAX subscriber enters the home, the consumer terminal will connect to the femtocell, which then connects to the network through a backhaul, such as an existing DSL or cable modem. The femtocell will provide benefits for both the subscriber and the operator. The subscriber will get excellent in-home coverage and maximum data rates, while the operator benefits from extended network coverage, more efficient spectrum usage and reduced customer churn. As a consumer product, the femtocell base station market is predicted to reach two million units in 2012 (from ABI Research, "WiMAX Market Analysis and Forecast"), but to achieve that, the femtocell must be affordable. Reaching these price targets will require an understanding of the standard and of the specific usage scenarios expected in femtocell deployments. This article proposes cost- and power-efficient techniques that will allow manufacturers to develop high-performance femtocells and picocells using WiMAX transceivers, such as the AD935x from Analog Devices. Next Page