# A Photolysis-Assist Molecular Communication for Tumor Biosensing
## 4 Numerical and Simulation Results
The time interval of symbols \(T_{b}=4t_{p}=0.2\) s.The red dashed line denotes the time to reach the peak concentration \(t_{p}=0.05\) s, the black dashed line indicates the synchronization delay time at the current symbol, the delay is \(t_{d}=0.0125\) s.  
Figure 3: The comparison of CIR curves between the diffusion with photolysis and without photolysis. The solid line denotes the signal when the photolysis reaction happens, while the dotted line denotes the signal when the molecules diffuse without photolysis reaction. \(t/s\) denotes that the unit of time is second. The red line denotes a symbol sequence with a time duration of 0.3 s, and the blue line denotes a symbol sequence with a time duration of 0.4 s.  
the proposed method mitigates the redundant molecules at the receiver side and also benefits from synchronization precision, the results indicate that the method proposed has better BER performance than the rest methods. The \(p\)-value of the proposed method with other methods also indicates that the proposed method is significantly effective in reducing BER when the SNR is the same. Meanwhile, The detection threshold could be decreased along with the ISI becoming small, which is helpful to improve the system performance. The simulation results validate the efficiency of the method proposed in the paper. Figure 7, four lines have been plotted, which denote four different symbol duration, respectively. We observe that the BER decreases as SNR increases, and the BER decreases when the symbol interval increase. More molecules from previous symbol slots have more time to diffuse when the symbol interval increases, the interference to the current symbol, ISI, is less. However, the bandwidth, as the reciprocal of time, decreases, and the channel capacity decreases as the time duration \(T_{b}\) increases because the channel capacity is inversely proportional to symbol duration. Figure 5: Comparison channel capacity C with the symbol duration \(T_{b}\) between two symbols, \(T_{b}=n*t_{p}\), \(n=1\),..., \(8\). \(J\) denotes the photolysis reaction coefficient. Std and Se denote standard deviations and standard error, respectively. Figure 6: (**a**) Bit Error Ratio (BER) performance comparison of the proposed method with the methods in the previous reference. dB denotes the unit of signal-to-noise ratio (SNR). (**b**) Std and Se denote standard deviations and standard error, respectively. p1, p2 and p3 denote the \(p\)-values of the comparison between the proposed method with photolysis, convexity and pure diffusion, respectively. Figure 8, the curves are the BER performance with the different distances between transmitter and receiver. It is observed that the BER performance improves as SNR increases; meanwhile, the performance of BER declines significantly as transmission distance increases. Due to diffusion's slow and stochastic nature, the signal amplification decays heavily as the distance between transmitter and receiver increases. Thus, It indicates that multiple transmitter-receiver pairs, as relays, will be used to achieve long-distance signal transmission as to the IoBNT network.