Interference signal avoiding device of a frequency hopping spread system and method thereof
An interference signal avoiding device of a frequency hopping spread system and a method thereof are disclosed. A method of transmitting/receiving an interference signal avoiding signal according to the present invention includes: determining a frequency hopping channel set and a parameter of an interference signal detector in consideration of characteristics of an interference signal; detecting whether there is an interference signal with respect to frequency hopping candidate channels that are to be used for the next frequency hopping by using the determined interference signal detector; transmitting a signal through a channel that is determined by the interference signal detector that there is no interference signal among the frequency hopping candidate channels; and searching a channel through which the signal is transmitted from the frequency hopping candidate channels in order to receive the transmitted signal.
1. A method of transmitting/receiving signals while avoiding interference signals, the method transmitting/receiving signals while avoiding homogeneous/heterogeneous interference signals present in an identical band in a Frequency Hopping Spread Spectrum (FHSS) system, comprising:
determining a frequency hopping channel set and a variable of an interference signal detector in consideration of characteristics of an interference signal;
detecting whether an interference signal is present on frequency hopping candidate channels to be used for next frequency hopping using the determined interference signal detector;
transmitting signals through a channel on which it is determined by the interference signal detector that no interference signal is present, among the frequency hopping candidate channels;
searching the frequency hopping candidate channels for a channel through which the signals are transmitted, and receiving the signals through the found channel; and
performing transmission power control using Signal-to-Noise power Ratio (SNR) values of channels on which no interference signal is present, when searching the frequency hopping candidate channels for the channel through which the signals are transmitted and transmitting the signals; and
wherein determining the frequency hopping channel set and the variable of the interference signal detector in consideration of characteristics of the interference signal comprises:
estimating a number of interference signals in a band;
determining the frequency hopping channel set based on the estimated number of interference signals; and
determining the variable of the interference signal detector based on the estimated number of interference signals and the determined frequency hopping channel set; and
wherein determining the variable of the interference signal detector based on the estimated number of interference signals and the determined frequency hopping channel set is configured to determine a detection time τ n and a threshold value λ n of the interference signal detector starting from time t n so that transmission performance of the FHSS system is maximized while satisfying a detection probability for interference signals to a desired level;
wherein detecting whether the interference signal is present on the frequency hopping candidate channels to be used for next frequency hopping using the determined interference signal detector comprises:
determining K frequency hopping candidate channels to be used for next frequency hopping; and
instantaneously detecting whether an interference signal is present on the determined K frequency hopping candidate channels; and
wherein instantaneously detecting whether the interference signal is present on the determined K frequency hopping candidate channels is configured to instantaneously detect whether an interference signal is present on an identical channel via a channel sensing technique, with respect to the determined K frequency hopping candidate channels by using the detection time τ n and the threshold value λ n before transmitting signals through the channel f i ;
wherein transmitting the signals through the channel on which it is determined by the interference signal detector that no interference signal is present, among the frequency hopping candidate channels, is configured to repeat a procedure for, if it is determined by the interference signal detector that no interference signal is present on a channel f i,1 , transmitting signals through the channel f i,1 regardless of whether an interference signal is present on subsequent K−1 channels and for, if it is determined by the interference signal detector that an interference signal is present on the channel f i,1 , determining whether an interference signal is present on a channel f i,2 and a transmitter of the FHSS system transmitting signals through the channel f i,2 only if it is determined that no interference signal is present on the channel f i,2 , thus searching the K frequency hopping candidate channels for a first channel on which no interference signal is present and transmitting signals through the first channel, and is also configured to, if it is determined that all of the K frequency hopping candidate channels are influenced by interference signals, stop transmitting signals until next frequency hopping time; and
wherein performing the transmission power control using the SNR values of channels on which no interference signal is present when searching the frequency hopping candidate channels for the channel through which the signals are transmitted and transmitting the signals is configured to estimate SNR values γ (t n−1 , t n ) of channels on which no interference signal is present when transmitting signals through the determined frequency hopping channel set, and then determine a transmission power value P out (t n ) during a next period by the following Equation (4):
P
out
(
t
n
)
=
min
(
P
max
′
max
(
P
min
′
γ
^
γ
_
(
t
n
-
1
,
t
n
)
P
out
(
t
n
-
1
)
)
)
(
4
)
wherein {circumflex over (γ)} denotes a target SNR value and P min and P max respectively denote minimum and maximum possible transmission power values.