Antenna Systems & Technology - Spring 2015 - (Page 8)

FEATURE ARTICLE Base Station Antenna Selection for LTE Networks Ivy Y. Kelly, Ph.D., Technology Development Strategist | Sprint Martin Zimmerman, Ph.D., Base Station Antenna Engineering Director | Commscope Ray Butler, MSEE, Wireless Network Engineering Vice President | CommScope Yi Zheng, Ph.D., Base Station Antenna Senior Engineer | CommScope Rapid mobile data growth is requiring the industry to use more sophisticated, higher-capacity access technologies like LTE, which supports many advanced antenna techniques. LTE requires precise containment of RF signals used to transmit mobile data, which can only be accomplished with high-performance antennas. This article will give an overview of antennas and their application in practical configurations for various types of LTE antenna techniques. Antenna Overview Antenna parameters can be separated into two categories, as shown below. Primary parameters (Table 1) are those specifically mentioned when defining the type of antenna used in a particular application. For a given antenna vendor, the primary parameters are enough to identify a specific model that can be used. Secondary parameters (Table 2) are those that impact performance and can be used to differentiate between similar models offered by different vendors. Parameter Definitions and/or Notes Number of arrays Modern antennas have 1-5 arrays or columns-possibly more if internal duplexing is used Frequency band Band of operation for each array in the antenna; affects size Horizontal HPBW (half-power beamwidth) Horizontal (azimuth) width of antenna's main beam; drives overlap between sectors; also called horizontal beamwidth (HBW) Length Physical length; drives the elevation HPBW and gain; concern for zoning and site leasing Gain Maximum power radiated in any direction; driven by length and azimuth HPBW Table 1. Primary Antenna Parameters Unfortunately, many of these parameters have not been clearly defined from an industry perspective. In an effort to bring consistency to the industry, the Next Generation Mobile Networks (NGNM) Alliance has released a BASTA white paper that suggests a single definition for each parameter. [1] Beamforming antennas are becoming increasingly important in LTE networks. Column patterns, broadcast patterns, and service beams are all formed and the parameters in Tables 1 and 2 apply to each. LTE Fundamentals Long term evolution (LTE) is a 3GPP-based standard using orthogonal frequency division multiple access (OFDMA) on the downlink and single carrier-frequency division multiple access (SC-FDMA) on the uplink. LTE supports: * Multiple channel (e.g., carrier) sizes (1.4, 3, 5, 10, 15 and 20 MHz) with carrier aggregation (CA) up to 100 MHz * More than 40 defined bands, supporting spectrum from 450 MHz to 3.8 GHz * Both time division duplexing (TDD) and frequency division duplexing (FDD) * Multiple antenna-related technologies, including various flavors of multiple-input, multiple-output (MIMO) and beamforming (BF) for up to eight downlink and four uplink antennas. The first LTE specification is part of 3GPP Release 8, which was frozen in December 2008. LTE-Advanced generally refers to the LTE features that are found in Release 10 and beyond. LTE-Advanced features include CA, eight-layer DL transmission, four-layer UL transmission, and enhanced inter-cell interference coordination (eICIC). [2] Release 10 features are just now being deployed. Release 11 introduces features such as coordinated multipoint (CoMP) and further enhanced ICIC (feICIC). In March 2015, 3GPP is due to complete Release 12, which contains features such as a new 3D channel model, active antenna systems 8 Antenna Systems & Technology Spring 2015 www.AntennasOnline.com http://www.AntennasOnline.com

Table of Contents for the Digital Edition of Antenna Systems & Technology - Spring 2015

Editor’s Choice
Base Station Antenna Selection for LTE Networks
Anticipating and Satisfying a Rising Demand for Wireless Communication Systems
Antennas
Components/Subsystems
Software / System Design
Test & Measurement
Industry News
Marketplace
CPRI Overcomes Head-End Challenges for DAS in Large Venues

Antenna Systems & Technology - Spring 2015