PowerLossChannel
This is a model of a wireless channel with a specified power propagation formula. The power propagation is given as an expression that is evaluated and then multiplied by the power field of the transmit properties before delivery to the receiver. For convenience, a variable named "distance" is available and equal to the distance between the transmitter and the receiver when the power propagation formula is evaluated. Thus, the expression can depend on this distance. The value of the power field should be interpreted as power at the transmitter but power density at the receiver. A receiver may multiply the power density with its efficiency and an area(typically the antenna area). A receiver can then use the resulting power to compare against a detectable threshold, or to determine signal-to-interference ratio, for example.
The default value of powerPropagationFactor is
1.0 / (4 * PI * distance * distance).
This assumes that the transmit power is uniformly distributed on a sphere of radius distance. The result of multiplying this by a transmit power is a power density (power per unit area). The receiver should multiply this power density by the area of the sensor it uses to capture the energy (such as antenna area) and also an efficiency factor which represents how effectively it capture the energy.
The power field of the transmit properties can be supplied by the transmitter as a record with a power field of type double. The default value provided by this channel is Infinity, which when multiplied by any positive constant will yield Infinity, which presumably will be above any threshold. Thus, the default behavior is to encounter no power loss and no limits to communication due to power.
In addition, this channel can have a specified limited transmission range. If a transmission range less than Infinity (the default) is specified, then receivers outside the specified range will not be notified of transmission, irrespective of power loss. The transmission range can be specified in one of two ways. Either it is the value of the range field in the defaultProperties parameter (a record) of this channel, or it is provided by the transmitter on each call to transmit() as a property argument. To use the latter mechanism, it is necessary that the property token be an instance of RecordToken with a field named "range" that can be converted to a double (i.e., it can be a double, an int, or a byte). The default value for range is Infinity, which indicates that by default, there is no range limit.
Any receiver that is within the specified range when transmit() is called will receive the transmission, unless the lossProbability parameter is set to greater than zero.
Field Detail |
public VisualSim.data.expr.Parameter powerPropagationFactor
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