ext_2G4_channel_multiatt

This is a channel model for ext_2G4_phy_v1

This is a non realistic channel model. It models NxN independent paths each with a configurable attenuation This attenuation can also be configured to change over time.

The default atennuation for all paths is set with the command line option -at=<attenuation>.

A file can be used to set the attenuation for some/all of the individual paths. This file is specified with the command line option -file=<att_matrix_file>

This file shall have one separate line per path like:
x y : {value|"<timed_attenuation_file>"}

Where:

• x is the transmitter number, x = 0..N-1
• y is the receiver number y != x
• N being the number of devices in the simulation
• value is a floating point value in dB
• <timed_attenuation_file> : is the path to a <timed_attenuation_file> as described below which applies to that path. Note that this file name shall be provided in between ""
• Not all paths need to be provided. Those omited will default to the attenuation provided from the command line.

The file names can be either absolute or relative to bin/

For both files, # is treated as a comment mark (anything after a # is discarded) Empty lines are ignored

Note that the Phy assumes the channel to be pseudo-stationary, that is, that the channel propagation conditions are static enough during a packet reception, that is, that the coherence time of the channel is much bigger than the typical packet length. Therefore the channel model won't be called to reevaluate conditions during a packet unless the devices which are transmitting change.

The <timed_attenuation_file>:

This file contains 2 columns, the first column represents time in microseconds (an integer value), and the second column the attenuation at that given time. The times shall be in ascending order.
If the simulation time is found in the file, the channel will use the corresponding attenuation value.
If the simulation time falls in between 2 times in the file, the channel will interpolate linearly the attenuation.
If the simulation time is before the first time value in the file, the channel will use the first atttenuation provided in the file.
If the simulation time is after the last time value in the file, the channel will use the last attenuation provided in the file.

The -atextra=<extra_attenuation> command line option:

You can provide an extra attenuation to be added to all paths, independently of how their attenuation was originally calculated, with the -atextra command line option. This extra_attenuation value will just be added to all paths.

An example:

./bs_2G4_phy_v1 -D=3 -s=Hola -channel=multiatt -argschannel -at=40 -file=paths_att_file.txt

paths_att_file.txt:

0 1 : 65
1 0 : 65
0 2 : "/myfolder/att_file.txt"
2 0 : "/myfolder/att_file.txt"
#Note that the paths from 1<->2 are not specified. They will default to the -at command line parameter

att_file.txt:

1000000    60
11000000  120
11000001   60

With this configuration, the radio traffic between device:

• device 0 and device 1 will have an attenuation of 65dB
• device 0 and device 2 will have an attenuation of
  • 60dB up to the first second
  • An increasing attenuation between 60->120 dB, between the first second and the 11th. At a rate of 6dB per second
  • A sudden reduction in the attenuation to 60 dB right after, which is maintained thereafter.