Java in Simulation Time

Pitfalls

• Use Java 1.4 compatibility, BCel cannot handle Java 5.0
• If more than one node use the same NetAddress, the simulation aborts prematurely without any error message.

Interesting Things

computeAvgConnectivity

Collisions

• RadioNoiseIndep and RadioSimpleStochastic both do not implement packet collisions on radio level:

 RadioNoiseIndep.receive():

     case Constants.RADIO_MODE_RECEIVING:
       if(Main.ASSERT) Util.assertion(signals>0);
       if(power_mW >= radioInfo.shared.threshold_mW
           &&  power_mW > signalPower_mW*thresholdSNR)
       {
         lockSignal(msg, power_mW, duration);
       }
       break;

• RadioNoiseAdditive implements additive superposition of radio signals and packet collisions. A signal is received only if it is stronger than thresholdSNR multiplied with the sum of the power of all other signals. Otherwise all signals are scrambled.

 RadioNoiseAdditive.receive():

     case Constants.RADIO_MODE_RECEIVING:
       if(power_mW > signalPower_mW  &&  power_mW >= totalPower_mW*thresholdSNR)
       {
         lockSignal(msg, power_mW, duration);
         setMode(Constants.RADIO_MODE_RECEIVING);
       }
       else if(type == SNR  
           &&  signalPower_mW < (totalPower_mW-signalPower_mW+power_mW)*thresholdSNR)
       {
         unlockSignal();
         setMode(Constants.RADIO_MODE_SENSING);
       }
       break;

Further Information

• JiST Website
• Presentation "Virtual Machine-based Simulation"