Cognitive radio spectrum sensing via CDMA receiver coding
View Patent ↗Technologies are generally described for cognitive radio spectrum sensing via Code Division Multiple Access (CDMA) receiver coding. A CDMA module in the front-end of a cognitive radio system may be used to sense spectrum. When the system is not decoding or transmitting signals, a modified CDMA receiver coding may replace a pseudorandom code used in decoding with relatively pure, non-random detection frequency to scan for energy from primary users of the spectrum. Multiplication of the received signal by spectrally pure codes in place of the CDMA code renders the CDMA processor effectively a scanning spectrum analyzer and may detect energy at multiple frequencies. The allocation of sub-bands and/or timing may be adjusted to account for the detected energy.
1. A method for cognitive radio spectrum sensing, the method comprising:
communicating with a radio frequency (RF) device by decoding a received RF signal employing a pseudorandom code during a communication session; and
upon completion of the communication session, scanning usage of a communication channel by replacing the pseudorandom code with a single frequency signal at a predefined frequency.
2. The method according to claim 1 , further comprising:
scanning a plurality of communication channels by modifying the predefined frequency and employing a group of adjacent frequencies in a “chirp” signal.
3. The method according to claim 1 , further comprising:
deriving a base band signal from the received RF signal.
4. The method according to claim 3 , wherein scanning the communication channel includes multiplying the base band signal with the single frequency signal prior to one of: filtering the base band signal, applying automatic gain control to the base band signal, or converting the base band signal to a digital signal.
5. The method according to claim 1 , wherein the pseudorandom code and the single frequency signal are generated at a Code Division Multiple Access (CDMA) module.
6. The method according to claim 1 , further comprising:
selecting the predefined frequency based on a level of energy detected at the communication channel.
7. The method according to claim 1 , further comprising:
scanning a plurality of communication channels by employing a plurality of frequencies, wherein a number and a timing of the plurality of frequencies is determined based on a level of energy detected at a first scanned communication channel.
8. An apparatus for enabling cognitive radio spectrum sensing, comprising:
a radio module for wireless communications via radio frequency (RF) signals;
a memory configured to store instructions;
a processor coupled to the memory, wherein the processor is adapted to execute the instructions, which when executed configure the processor to:
communicate with an RF device by causing the radio module to decode a received RF signal employing a pseudorandom code during a communication session; and
upon completion of the communication session, determine usage of a communication channel by causing the radio module to replace the pseudorandom code with a single frequency signal at a predefined frequency.
9. The apparatus according to claim 8 , wherein the processor is further configured to:
cause the radio module to scan a plurality of communication channels by modifying the predefined frequency and employing a group of adjacent frequencies in a “chirp” signal.
10. The apparatus according to claim 8 , wherein the processor is further configured to:
cause the radio module to derive a base band signal from the received RF signal and multiply the base band signal with the single frequency signal in order to scan the communication channel.
11. The apparatus according to claim 8 , further comprising a Code Division Multiple Access (CDMA) module configured to generate the pseudorandom code and the single frequency signal prior to one of: a base band filtering module, an automatic gain control module, and an analog-to-digital converter module.
12. The apparatus according to claim 8 , wherein the radio module further comprises at least one of: a pre-filter module, a low noise amplifier module, and/or a down-conversion module.
13. A non-transitory computer-readable storage medium having instructions stored thereon for a method of cognitive radio spectrum sensing to be executed in a computing device with radio communication capability, the method comprising:
communicating with a radio frequency (RF) device by decoding a received RF signal employing a pseudorandom code during a communication session; and
upon completion of the communication session, scanning usage of a communication channel by replacing the pseudorandom code with a single frequency signal at a predefined frequency.
14. The non-transitory computer-readable storage medium according to claim 13 , wherein the method further comprises:
scanning a plurality of communication channels by modifying the predefined frequency and employing a group of adjacent frequencies in a “chirp” signal.
15. The non-transitory computer-readable storage medium according to claim 13 , wherein the method further comprises:
deriving a base band signal from the received RF signal.
16. The non-transitory computer-readable storage medium according to claim 15 , wherein decoding the received RF signal includes multiplying the base band signal with the pseudorandom code.
17. The non-transitory computer-readable storage medium according to claim 15 , wherein scanning the communication channel includes multiplying the base band signal with the single frequency signal prior to one of: filtering the base band signal, applying automatic gain control to the base band signal, or converting the base band signal to a digital signal.
18. The non-transitory computer-readable storage medium according to claim 13 , wherein the pseudorandom code and the single frequency signal are generated at a Code Division Multiple Access (CDMA) module.
19. The non-transitory computer-readable storage medium according to claim 13 , wherein the method further comprises:
selecting the predefined frequency based on a level of energy detected at the communication channel.
20. The non-transitory computer-readable storage medium according to claim 13 , wherein the method further comprises:
scanning a plurality of communication channels by employing a plurality of frequencies, wherein a number and a timing of the plurality of frequencies is determined based on a level of energy detected at a first scanned communication channel.