The propagation of right-hand circularly polarized Airy-Gaussian beams (RHCPAiGBs) through slabs of right-handed materials (RHMs) and left-handed materials (LHMs) is investigated analytically and numerically with the transfer matrix method. An approximate analytical expression for the RHCPAiGBs passing through a paraxial ABCD optical system is derived on the basis of the Huygens diffraction integral formula. The intensity and the phase distributions of the RHCPAiGBs through RHMs and LHMs are demonstrated. The influence of the parameter χ0 on the propagation of RHCPAiGBs through RHM and LHM slabs is investigated. The RHCPAiGBs possess transverse-momentum currents, which shows that the physics underlying this intriguing accelerating effect is that of the combined contributions of the transverse spin and transverse orbital currents. Additionally, we go a step further to explore the radiation force including the gradient force and scattering force of the RHCPAiGBs.
In this study, a mixed massive random access scheme is considered where part of users transmit both common information and user-specific information, while others transmit only common information. In this scheme, common information is transmitted by index modulation (IM)–aided unsourced random access (URA), while user-specific information is by IM-aided sourced random access (SRA). Practically, IM-aided URA partitions channel blocks of one transmission frame into multiple groups and then employs the IM principle to activate only part of the channel blocks in each group. IM-aided SRA allocates multiple pilot sequences to each user and activates only one pilot sequence whose index carries the data information. At the receiver, the covariance-based maximum likelihood detection (CB-MLD) is employed to recover the active compressed sensing (CS) code words of URA and information of SRA jointly. To stitch the common information at different blocks of URA, a modified tree decoder is proposed to take the IM constraint into account. Furthermore, to relax the strict threshold requirement and improve the performance, an iterative CS detector and tree decoder are employed to decode the common information, where successive signal reconstruction and interference cancellation are utilized. Finally, computer simulations are given to demonstrate the performance of the proposed scheme.
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