SIPAM-4 scheme improves bit error rate performance in MISO X-ray communication system

X-ray communication (XCOM) technology, which uses X-ray as the carrier wave, is expected to solve the problem of reentry blackout region communication with its good penetration characteristics. In order to mitigate the effects of non-linear distortion of the gated X-ray tube (GMXT), the multiple-input single-output (MISO) technique has been introduced in XCOM systems. A pulse amplitude modulation scheme based on superimposed intensity (SIPAM) was proposed and achieved by configuring GMXTs with on/off keying modulation in MISO XCOM system. The feasibility of the proposed SIPAM scheme in XCOM was numerically investigated through Monte Carlo simulations. As the divergence angle of the GMXT increases, the optical power distribution tends to be more uniform in the receiving plane. It can greatly relax the requirements for link alignment. After that, we conduct a proof-of-concept experiment for the SIPAM with four levels (SIPAM-4) scheme by employing two GMXTs and an LYSO-SiPM-based X-ray detector. The experimental results show that when the bit error rate is within the forward error correction limit of 3.8 × 10−3, the SIPAM-4 scheme can reach a maximum communication rate of 1.20 Mbps, which is 20% higher than the conventional PAM-4 scheme. It can be included that the proposed MISO based the SIPAM-4 modulation scheme could improve the performance of the X-ray communication system.