Low complexity frequency hopping solution for performance testing system and method
View Patent ↗A system and method for low complexity frequency hopping simulation for communication device performance testing is disclosed. A baseband and channel model combination in a baseband processing module ( 602 ) of a testing system ( 600 ) reduces the required number of computations while retaining accuracy. A simulated channel is generated ( 612 ) with a bandwidth required for frequency hopping, and the hopping is simulated by shifting ( 614 ) the channel ( 612 ) instead of the signal ( 606 ). Signal attenuation by the shifted channel ( 615 ) is modeled in the baseband processing module ( 602 ), and the resulting simulated signal ( 610 ) is then up-sampled ( 628 ) to the proper frequency for output to the test device ( 634 ).
1. A method for simulation of a frequency hopping radio system, the method comprising:
generating a pre-compensated simulated channel profile at a sampling rate corresponding to a data rate of a simulated baseband information signal, the pre-compensated simulated channel profile having a center frequency that is offset from a center frequency of the simulated baseband information signal by a frequency offset;
filtering the simulated baseband information signal by the pre-compensated simulated channel profile to obtain a simulated baseband output signal;
elevating the simulated baseband output signal to an elevated frequency to obtain a simulated output test signal, wherein the elevated frequency is equal to a carrier frequency plus an inverse of the frequency offset; and
transmitting the simulated output test signal.
2. A method according to claim 1 , wherein generating the pre-compensated simulated channel profile further comprises:
generating a simulated channel profile;
shifting the simulated channel profile by the frequency offset to obtain a shifted channel profile; and
decreasing a sampling rate of the shifted channel profile to obtain the pre-compensated simulated channel profile.
3. A method according to claim 2 , wherein shifting the simulated channel profile further comprises:
computing a hopping index corresponding to a channel frequency; and
obtaining the frequency offset corresponding to the hopping index.
4. A method according to claim 3 , further comprising setting the frequency hopping pattern by the hopping index.
5. A method according to claim 2 , further comprising varying the frequency offset over time according to a frequency hopping pattern.
6. A method according to claim 1 , further comprising testing a test device with the simulated output test signal.
7. A method according to claim 6 , further comprising:
receiving the simulated output test signal;
detecting the simulated output test signal;
down converting the simulated output test signal to the data rate of the simulated baseband information signal; and
decoding the simulated output signal to obtain the baseband information signal.
8. A test system for simulation of a frequency hopping radio system, the test system comprising:
a baseband signal generator configured to generate a baseband information signal at a baseband data rate and centered at a baseband frequency; and
a channel simulator coupled to the baseband signal generator and configured to filter the baseband information signal by a down sampled channel profile to obtain a filtered baseband information signal, the channel simulator comprising:
a reverse hopping module configured to shift a channel profile by a hopping frequency corresponding to a hopping index to obtain a shifted channel profile having a center frequency offset from the baseband frequency by the hopping frequency; and
a down sampler coupled to the reverse frequency hopping module and configured to decrease a sampling rate of the shifted channel profile to the baseband data rate to obtain the down sampled channel profile.
9. A system according to claim 8 , wherein the channel simulator further comprises a filter coupled to the baseband signal generator and to the down sampler, the filter being configured to filter the baseband information signal by the down sampled channel profile.
10. A system according to claim 8 , further comprising a channel generator coupled to the reverse frequency hopping module, the channel generator being configured to generate the channel profile corresponding to a plurality of channel signals.
11. A system according to claim 8 , further comprising a baseband processor configured to process the baseband information signal to generate the filtered baseband information signal, wherein the baseband processor includes the baseband signal generator and the channel simulator.
12. A system according to claim 11 , further comprising a RF processing module coupled to the baseband processor and configured to elevate the filtered baseband information signal to a channel frequency to obtain a down link test signal.