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Diffstat (limited to 'pathloss/pathloss-func.py')
| -rw-r--r-- | pathloss/pathloss-func.py | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/pathloss/pathloss-func.py b/pathloss/pathloss-func.py new file mode 100644 index 0000000..a9e9a65 --- /dev/null +++ b/pathloss/pathloss-func.py @@ -0,0 +1,112 @@ +# pathloss-func.py + +# (C) 2016 by Harald Welte <laforge@gnumonks.org> +# All Rights Reserved +# +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 2 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see <http://www.gnu.org/licenses/>. + +from Gnumeric import GnumericError, GnumericErrorVALUE +import Gnumeric +import string +import math + +def lambda_by_mhz(freq_mhz): + return 300/freq_mhz + +def func_fsl(freq_mhz, dist_m): + '@FUNCTION=PATHLOSS_FREESPACE\n'\ + '@SYNTAX=pathloss_freespace(freq_mhz, dist_m)\n'\ + '@DESCRIPTION=Compute Free Space Path Loss (in dB)\n'\ + '@SEEALSO=pathloss_egli,pathloss_hata\n' + + wavelen = lambda_by_mhz(freq_mhz) + + return -20 * math.log10(wavelen / (4*3.1416*dist_m)) + +def hata_ch(envi, freq_mhz, rx_ant_m): + logfreq = math.log10(freq_mhz) + ch = 0 + if envi == 'city_small' or envi == 'city_medium': + ch = 0.8 + (1.1 * logfreq - 0.7)*rx_ant_m - (1.56 * logfreq) + elif envi == 'city_large': + if freq_mhz < 200: + ch = 8.29 * math.pow(math.log10(1.54*rx_ant_m), 2) - 1.1 + elif freq_mhz > 200: + ch = 3.2 * math.pow(math.log10(11.75*rx_ant_m), 2) - 4.97 + return ch + +def hata_cm(envi, freq_mhz): + logfreq = math.log10(freq_mhz) + att = 0 + if freq_mhz <= 1500: + if envi == 'open_area' or envi == 'rural': + # https://en.wikipedia.org/wiki/Hata_model_for_open_areas + att = -4.78 * math.pow(logfreq, 2) + 18.33 * logfreq - 40.94 + elif envi == 'suburban': + # https://en.wikipedia.org/wiki/Hata_model_for_suburban_areas + att = -2 * math.pow(logfreq/28, 2) - 5.4 + else: + if envi == 'city_large': + att = 3 + else: + att = 0 + return att + +def func_hata(envi, freq_mhz, dist_m, bts_ant_m, ms_ant_m): + '@FUNCTION=PATHLOSS_HATA\n'\ + '@SYNTAX=pathloss_hata(environment, freq_mhz, dist_m, bts_ant_m, ms_ant_m)\n'\ + '@DESCRIPTION=Compute Path Loss (in dB) as per Hata Model\n'\ + '@SEEALSO=pathloss_freespace,pathloss_hata\n' + + # FIXME: valid for 150MHz - 2GHz, MS 1-10m, BS 30-200m, dist # 1-10km + environs = ('open_area', 'rural', 'suburban', 'city_small', + 'city_medium', 'city_large') + if not envi in environs: + raise GnumericError,GnumericErrorVALUE + + # http://morse.colorado.edu/~tlen5510/text/classwebch3.html + if freq_mhz <= 1500: + c0 = 69.55 + cf = 26.16 + else: + c0 = 46.3 + cf = 33.9 + + # https://en.wikipedia.org/wiki/Hata_model_for_urban_areas + hata = c0 + cf * math.log10(freq_mhz) + hata -= 13.82 * math.log10(bts_ant_m) + hata -= hata_ch(envi, freq_mhz, ms_ant_m) + hata += (44.9 - 6.55 * math.log10(bts_ant_m)) * math.log10(dist_m/1000) + # subtract correction for open_area / suburban + hata += hata_cm(envi, freq_mhz) + + return hata + +def func_egli(freq_mhz, dist_m, tx_ant_m, rx_ant_m): + '@FUNCTION=PATHLOSS_EGLI\n'\ + '@SYNTAX=pathloss_egli(freq_mhz, dist_m, tx_ant_m, rx_ant_m)\n'\ + '@DESCRIPTION=Compute Path Loss (in dB) as per Egli Model\n'\ + '@SEEALSO=foo\n' + + # https://en.wikipedia.org/wiki/Egli_model + att = -20 * math.log10(rx_ant_m*tx_ant_m / (dist_m*dist_m)) + att += 20 * math.log10(freq_mhz/40) + + return att + +pathlossfunc_functions = { + 'pathloss_freespace': ('ff', 'freq_mhz, dist_m', func_fsl), + 'pathloss_egli': ('ffff', 'freq_mhz, dist_m, tx_ant_m, rx_ant_m', func_egli), + 'pathloss_hata': ('sffff', 'environ, freq_mhz, dist_m, bts_ant_m, ms_ant_m', func_hata), +} |