Antenna Systems & Technology - Winter 2013 - (Page 8)

FEATURE ARTICLE LTE's MIMO Requirement Strengthens the Need for Active Antenna Systems By Jeff Shamblin, Chief Scientist - Ethertronics More than 200 LTE networks are in commercial service worldwide, an amount that will double over the next five years, according to 4G Americas. What do they all have in common? A need for active antenna systems to meet LTE's Multiple Input, Multiple Output (MIMO) requirements. Those requirements include MIMO at both base stations and user devices. The latter is challenging for at least five reasons: * Multiple antennas. MIMO requires at least two antennas where 3G required one, and that amount will increase as MIMO designs shift to 4x4 and 8x8. Finding room for all of those LTE antennas - plus those for 3G/2G fallback, GPS, Wi-Fi, Bluetooth and NFC - will get even more difficult as the trend toward higher order MIMO collides with the trend toward thinner devices. * Unprecedented band fragmentation. LTE is designed to work in more than 40 bands between 450 MHz and 2.7 GHz, and roughly half of them are in use by today's devices. Building a smartphone or tablet that can roam globally on only LTE, as opposed to falling back to 3G in areas where LTE isn't yet available, would require supporting up to 40 bands. Even a small subset of that number is challenging in terms of finding room for all of the necessary antennas in MIMO configurations of 2x2 or greater, plus those for Wi-Fi and other technologies. * Operators prefer lower bands for LTE. The lower the frequency, the lower the density of base stations, which means the operator has lower CapEx and OpEx. Lower bands such as 700 MHz also provide better in-building coverage, which is critical for customer satisfaction, wireline displacement and pursuing the burgeoning "Internet of Things" (IoT) market opportunity. Operators are now looking at the 600 MHz band for future use. But lower frequency bands also require physically larger antennas, which forces device OEMs and their RF suppliers to get creative when it comes to finding ways to fit them into sleek smartphones. IoT devices also often have limited space available for antennas. * Thin is in. The space inside smartphones and tablets is declining 25 percent annually due to the trend toward thinner, sleeker devices. The display and battery get priority, leaving the processor, memory, antenna system and other components to battle for the remaining space. The thin trend coupled with MIMO and lower frequencies (700 MHz) requiring physically larger antennas is placing significant pressure on OEMs and their design teams to make it all work. * Inexperience. As LTE coverage grows, so does the pressure on device vendors to add LTE to their products. That's challenging enough for experienced smartphone vendors simply because LTE has the learning curve that comes with a new technology. It's even more challenging for many M2M (Machine to Machine) vendors, which often have little or no experience embedding cellular technology into their products. Device OEMs and their RF suppliers have two options for not only overcoming these challenges, but turning them into market-differentiation opportunities: They can work smarter, or they can work harder. Greater Flexibility, Reliability and Performance Active antenna systems enable device OEMs and their RF suppliers to work smarter. That's because compared to traditional passive antennas, active systems provide far more flexibility in terms of design and performance. In fact, active antennas are the easiest way to accommodate LTE's band fragmentation and MIMO requirements, as well as operator preferences for low bands, all while meeting the trend toward increasingly thin devices. 8 Antenna Systems & Technology Winter 2013 www.AntennasOnline.com http://www.AntennasOnline.com

Table of Contents for the Digital Edition of Antenna Systems & Technology - Winter 2013

Editor’s Choice
LTE's MIMO Requirement Strengthens the Need for Active Antenna Systems
Optimizing Cell and Tower Sites During the Data Explosion
Improve Passive Intermodulation Performance with Specialty High-Frequency Circuit Materials
Next Generation Wireless: Riding on the Back of Millimeter Waves
Antennas
Components/Subsystems
Test & Measurement
Marketplace
Industry News

Antenna Systems & Technology - Winter 2013