42 APRIL 2014 MICROWA VES & RF INCREASINGLY, DISTRIBUTED ANTENNA systems (DASs) have been providing much-needed wireless service in locations rang- ing from sports stadiums to private yachts. The term “DAS” describes a network of antennas and interconnects that route telecommunications signals throughout a localized environ- ment. The goal of a DAS is to bring wireless connectivity to areas where macrocells cannot adequately meet demand. There are three main ty pes of distributed -antenna systems, yet all of them encounter challenges when it comes to instal- lation. Several companies have intriguing methods of solving those challenges, such as the need to implement high-capacity data links alongside often necessary public-safety bands. DASs are becoming more commonplace in corporate, public- transportation, and entertainment/shopping facilities (Fig. 1). When asked what is influencing this trend, Colin Abrey, chief marketing officer of Zinwave, replies, “The biggest one at the moment is the proliferation of mobile data. To generate the best performance, you need to put the user close to the antenna. There is also an increasing demand for public-safety services to be available inside a building.” Wireless network operators have an incentive to provide coverage wherever their customers require network access. This demand for coverage precipitates a need for solutions that can maintain connectivity indoors, out- doors, and on the go (Fig. 2). Because macrocells are designed for coverage over large out- door areas, the communications link between a user’s devices inside a building and the tower may not always have a strong signal. A weak or sporadic signal would induce a much lower- capacity link and put less data at the fingertips of the user. DASs and small cells have been promoted as solutions for these prob- lems. These approach es differ by t he scenarios in which they provide the best solution. According to Abrey , “DASs would not typically be found in very small buildings or homes. Smaller envi- ronments that are single service would not typically use DASs; they would use small cells. A medium to large building, about 50,000 square feet and beyond, would be the realm of DASs, as well as multi-service environments like 2G, 3G, and 4G-LTE.” The oldest style of the distributed antenna system is fully pas- sive. These systems are designed with a repeater antenna, which is mounted on roofs to relay the cell-tower signals to distributed antennas within the building. Passive DASs often require long DASs Bring Capacity Both Indoors And Outdoors To solve the demands of high data rates in buildings, in stadiums, and on public transportation, distributed antenna systems are bringing the antennas to the people. RF Essentials JEAN-JACQUES DELI SLE | Technical Engineering Editor BASIC DISTRIBUTED ANTENNA SYSTEM Donor Antenna (Roof Mounted) BDABi-Directional AmplifierIndoor Antennas (Ceiling Mounted) Antenna T aps or "Splitters" Coaxial Cable IndoorAntenna CELL SIGNALNETWORKPROVIDER 1. An in-building DAS can be implemented by routing a high-speed wire- less link from a cell tower indoors with an externally mounted antenna. 2. The demand for constant connectivity to high-capacity links is driving network operators to seek indoor routing solutions in train tunnels and other public-transit systems.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
system take flight. At NuWaves, SWaP (Size, Weight and Power) is the name of the game.We oer COTS products and custom solutions that meet the demanding needs
of today’s military, government and industrial customers.