Signal detection method and signal receiving device for enhancing reliability of code rate search
A signal detection method associated with a constellation diagram corresponding to a modulation scheme is provided for enhancing the reliability of code rate search. A mask is provided between two adjacent constellation points in the modulation scheme. The signal detection method includes: receiving a plurality of signals, and mapping the plurality of signals to the constellation diagram; when a first signal among the plurality of signals is located in the mask, discarding the first signal; and when a second signal among the plurality of signals outside located in the mask, determining a constellation point corresponding to the second signal.
1. A signal detection method, associated with a constellation diagram corresponding to a modulation scheme, for enhancing reliability of code rate search, a mask being included between two adjacent constellation points in the constellation diagram, the signal detection method comprising:
receiving, by a receiver, a plurality of signals;
mapping, using a processor, the plurality of signals to the constellation diagram;
when a first signal among the plurality of signals is located in the mask, discarding the first signal; and
when a second signal among the plurality of signals is not located in the mask, determining a constellation point corresponding to the second signal.
2. The signal detection method according to claim 1 , wherein when the second signal among the plurality of signals is not located in the mask, the step of determining the constellation point corresponding to the second signal comprises:
obtaining a position on the constellation diagram of the second signal mapped to the constellation diagram, and determining that a constellation point closest to the position as the constellation point corresponding to the second signal.
3. The signal detection method according to claim 1 , wherein a border of the mask is perpendicular to a connecting line between the two adjacent constellation points.
4. The signal detection method according to claim 1 , further comprising:
corresponding each code rate of a plurality of code rates to a constellation diagram distribution comprising different constellation points in the constellation diagram; and
determining whether the constellation points corresponding to the plurality of signals match a predetermined constellation diagram distribution, and accordingly determining whether the plurality of signals correspond to a code rate corresponding to the predetermined constellation diagram distribution.
5. The signal detection method according to claim 4 , wherein the predetermined constellation diagram distribution corresponds to a predetermined code rate, and the step of determining whether the constellation points corresponding to the plurality of signals match the predetermined constellation diagram distribution comprises:
selecting constellation points included in the predetermined constellation diagram distribution from the constellation points of the modulation scheme;
determining whether the constellation points corresponding to the plurality of signals are constellation points included in the predetermined constellation diagram distribution;
when it is determined that the constellation point corresponding to one of the plurality of signals is a constellation point of the predetermined constellation diagram distribution, adding a counter value by one; and
out of the plurality signals located outside the mask, determining a ratio of the constellation points located in the predetermined constellation diagram distribution according to the counter value.
6. The signal detection method according to claim 5 , wherein the step of determining whether the plurality of signals correspond to the code rate corresponding to the constellation diagram distribution comprises:
setting a threshold; and
when the ratio is greater than the threshold, determining that the plurality of signals correspond to the predetermined code rate corresponding to the predetermined constellation diagram distribution.
7. A signal receiving device, performing a signal detection method to enhance reliability of code rate search, the signal detection method associated with a constellation diagram corresponding to a modulation scheme, a mask being included between two adjacent constellation points of the constellation diagram, the signal detection device comprising:
a signal receiving module, receiving a plurality of signals;
a processing device, coupled to the signal receiving module, executing a program code; and
a storage unit, coupled to the storage device, storing the program code, the program code instructing the processing device to perform steps of:
mapping the plurality of signals received to the constellation diagram;
when a first signal among the plurality of signals is located in the mask, discarding the first signal; and
when a second signal among the plurality of signals is not located in the mask, determining a constellation point corresponding to the second signal.
8. The signal receiving device according to claim 7 , wherein when the second signal among the plurality of signals is not located in the mask, the step of determining the constellation point corresponding to the second signal comprises:
obtaining a position on the constellation diagram of the second signal mapped to the constellation diagram, and determining that a constellation point closest to the position as the constellation point corresponding to the second signal.
9. The signal receiving device according to claim 7 , wherein a border of the mask is perpendicular to a connecting line between the two adjacent constellation points.
10. The signal receiving device according to claim 7 , wherein the program code further instructs the processing device to perform steps of:
corresponding each code rate of a plurality of code rates to a constellation diagram distribution comprising different constellation points in the constellation diagram; and
determining whether the constellation points corresponding to the plurality of signals match a predetermined constellation diagram distribution, and accordingly determining whether the plurality of signals correspond to a code rate corresponding to the predetermined constellation diagram distribution.
11. The signal receiving device according to claim 10 , wherein the predetermined constellation diagram distribution corresponds to a predetermined code rate, and the step of determining whether the constellation points corresponding to the plurality of signals match the predetermined constellation diagram distribution comprises:
selecting constellation points included in the predetermined constellation diagram distribution from the constellation points of the modulation scheme;
determining whether the constellation points corresponding to the plurality of signals are constellation points included in the predetermined constellation diagram distribution;
when it is determined that the constellation point corresponding to one of the plurality of signals is a constellation point of the predetermined constellation diagram distribution, adding a counter value by one; and
out of the plurality signals located outside the mask, determining a ratio of the constellation points located in the predetermined constellation diagram distribution according to the counter value.
12. The signal receiving device according to claim 11 , wherein the step of determining whether the plurality of signals correspond to the code rate corresponding to the constellation diagram distribution comprises:
setting a threshold; and
when the ratio is greater than the threshold, determining that the plurality of signals correspond to the predetermined code rate corresponding to the predetermined constellation diagram distribution.