Radio Frequency Engineering

WCDMA Network’s Physical or Antenna Parameter Optimization Procedure and Purpose

Before tuning physical parameter or antenna parameter an engineer should have clear understanding on flowing issue:
            A)     Basic principle of Antenna.
            B)     Antenna selection procedure for different radio environment.
            C)     Antennacharacteristics and Classification.
An antenna is a passive device which can transmit and receive radio waves. When antenna transmits its convert RF current into electromagnetic (EM) waves and when it receives converts electromagnetic (EM) waves into RF currents. 

For every radio network, network parameter may be categorized into two parts; one is physical parameter and another is logical parameter. Due to improper combination of physical parameters WCDMA network service may hamper at a large scale. Flowing physical parameter need to tune for optimum network service:
                1.      Antenna’s heights.
                2.      Antenna’s Electrical Tilt.
                3.      Antenna’s Mechanical Tilts.
                4.      Antenna’s Azimuth or Orientation.
The most probable reason of Physical Parameter tuning is listed below:
                 a)       Poor coverage issue at indoor and outdoor.
                 b)      Signal overshooting issue.
                 c)      Pilot pollution reduction issue.
                 d)      Cluster rearrangement/load balancing or traffic sharing issue.
                 e)      Different purpose optimization such as new site/cell addition and deletion.
WCDMA Radio Network serving area

     Antenna Heights: An Antenna height is one of the most significant physical parameter of WCDMA network. By tuning antenna’s height we can control coverage area of WCDMA network. That is antenna height is directly proportional to the maximum coverage area. Depends on the elevation (Sea level height) of geographical surface theoretical value of antenna heights may differ.
     One of the alternative soft parameter of Antenna height is Transmit Power.  Alternative Physical parameters are Electrical Tilt and Mechanical Tilt.

Antenna height VS Coverage

        Antenna’s Electrical Tilt: The antenna’s Electrical Tilt represents an electrical inclination or electrical angle of the antenna from its axis. There are two types of electrical tilts; these are Up Tilt and Down Tilt. Generally electrical Up tilt applies for expand coverage or to strengthen signal and down tilt applies for shrinking coverage. Alternative Physical parameters of Electrical tilt are Antenna heights and Mechanical Tilt.
Antenna Electrical Tilt


     Antenna’s Mechanical Tilt:  Antenna’s Mechanical Tilt represents a mechanical inclination or mechanical angle of the antenna from its axis. There are two types of Mechanical tilts; these are Up Tilt and Down Tilt. Generally Mechanical Up tilt applies for expand coverage and down tilt applies for shrinking coverage. The tuning impact of antenna’s mechanical tilt is almost similar with Antenna’s “Electrical Tilt”.  
Antenna Electrical Tilt vs Mechanical Tilt


     Antenna’s Azimuth or Orientation: Generally WCDMA system uses highly directional cross polarized (±45®) antenna. Here, Antenna’s Azimuth or Orientation represents on which direction antenna faces. During the selections of WCDMA antenna we need to consider few antenna characteristics such as polarity, horizontal and vertical beam width, antenna gain, Maximum transmits power etc. Antenna’sazimuth is very useful parameter during the customer complain solution process.  If antenna beam width is 65® and three cell site; then the maximum antenna azimuth tuning is ±20®.

Antenna Azimuth tuning proposal