.. include:: replace.txt ++++++++++++++++++++++++++++++++++++++ Design documentation ++++++++++++++++++++++++++++++++++++++ -------- Overview -------- The Antenna module provides: #. a new base class (AntennaModel) that provides an interface for the modeling of the radiation pattern of an antenna; #. a set of classes derived from this base class that each models the radiation pattern of different types of antennas. ------------ AntennaModel ------------ The AntennaModel uses the coordinate system adopted in [Balanis]_ and depicted in Figure :ref:fig-antenna-coordinate-system. This system is obtained by traslating the cartesian coordinate system used by the ns-3 MobilityModel into the new origin :math:o which is the location of the antenna, and then transforming the coordinates of every generic point :math:p of the space from cartesian coordinates :math:(x,y,z) into spherical coordinates :math:(r, \theta,\phi). The antenna model neglects the radial component :math:r, and only considers the angle components :math:(\theta, \phi). An antenna radiation pattern is then expressed as a mathematical function :math:g(\theta, \phi) \longrightarrow \mathcal{R} that returns the gain (in dB) for each possible direction of transmission/reception. All angles are expressed in radians. .. _fig-antenna-coordinate-system: .. figure:: figures/antenna-coordinate-system.* :align: center Coordinate system of the AntennaModel --------------- Provided models --------------- In this section we describe the antenna radiation pattern models that are included within the antenna module. IsotropicAntennaModel +++++++++++++++++++++ This antenna radiation pattern model provides a unitary gain (0 dB) for all direction. CosineAntennaModel ++++++++++++++++++ This is the cosine model described in [Chunjian]_: the antenna gain is determined as: .. math:: g(\phi, \theta) = \cos^{n} \left(\frac{\phi - \phi_{0}}{2} \right) where :math:\phi_{0} is the azimuthal orientation of the antenna (i.e., its direction of maximum gain) and the exponential .. math:: n = -\frac{3}{20 \log_{10} \left( \cos \frac{\phi_{3dB}}{4} \right)} determines the desired 3dB beamwidth :math:\phi_{3dB}. Note that this radiation pattern is independent of the inclination angle :math:\theta. A major difference between the model of [Chunjian]_ and the one implemented in the class CosineAntennaModel is that only the element factor (i.e., what described by the above formulas) is considered. In fact, [Chunjian]_ also considered an additional antenna array factor. The reason why the latter is excluded is that we expect that the average user would desire to specify a given beamwidth exactly, without adding an array factor at a latter stage which would in practice alter the effective beamwidth of the resulting radiation pattern. ParabolicAntennaModel +++++++++++++++++++++ This model is based on the parabolic approximation of the main lobe radiation pattern. It is often used in the context of cellular system to model the radiation pattern of a cell sector, see for instance [R4-092042a]_ and [Calcev]_. The antenna gain in dB is determined as: .. math:: g_{dB}(\phi, \theta) = -\min \left( 12 \left(\frac{\phi - \phi_{0}}{\phi_{3dB}} \right)^2, A_{max} \right) where :math:\phi_{0} is the azimuthal orientation of the antenna (i.e., its direction of maximum gain), :math:\phi_{3dB} is its 3 dB beamwidth, and :math:A_{max} is the maximum attenuation in dB of the antenna. Note that this radiation pattern is independent of the inclination angle :math:\theta. .. [Balanis] C.A. Balanis, "Antenna Theory - Analysis and Design", Wiley, 2nd Ed. .. [Chunjian] Li Chunjian, "Efficient Antenna Patterns for Three-Sector WCDMA Systems", Master of Science Thesis, Chalmers University of Technology, GĂ¶teborg, Sweden, 2003 .. [Calcev] George Calcev and Matt Dillon, "Antenna Tilt Control in CDMA Networks", in Proc. of the 2nd Annual International Wireless Internet Conference (WICON), 2006 .. [R4-092042a] 3GPP TSG RAN WG4 (Radio) Meeting #51, R4-092042, Simulation assumptions and parameters for FDD HeNB RF requirements.