[简介] 目前的语义通信研究尚未阐明语义编码与经典信道编码之间的关系、语义编码在现有通信框架中的可行性，以及影响语义编码的关键因素等。文章对基于联合信源信道编码的语义通信系统进行了理论分析，设计了语义编码与经典信道编码的融合实验，展示了语义编码的潜在优势，并探索了语义编码与经典信道编码之间的关系。

[简介]为更好地发展下一代移动通信技术，加快5G/6G建设，需将发力点由“面向企业”的2B（To Business）向“为了企业”的4B（For Business）转变。从2B到4B，是从供给侧主导向需求侧主导的转变，是从“供给外生赋能”向“供需内生协同”本质的转变。应由垂直行业主导公专网应用的标准制定与生态建设，从顶层设计开始，将数字技术融入到垂直行业数字化转型之中，实现5G/6G公专网发展从2B到4B的转变。

[Introduction] In the context of edge computing environments in general and the metaverse in particular, federated learning (FL) has emerged as a distributed machine learning paradigm that allows multiple users to collaborate on training a shared machine learning model locally, eliminating the need for uploading raw data to a central server. It is perhaps the only training paradigm that preserves the privacy of user data, which is essential for computing environments as personal as the metaverse. However, the original FL architecture proposed is not scalable to a large number of user devices in the metaverse community. To mitigate this problem, hierarchical federated learning (HFL) has been introduced as a general distributed learning paradigm, and has since then inspired and led to a number of research works. In this paper, we present several types of HFL architectures, with a special focus on the three-layer client-edge-cloud HFL architecture, which is most pertinent to the metaverse due to its delay-sensitive nature. We also examine works that take advantage of the natural layered organization of three-layer client-edge-cloud HFL to tackle some of the most challenging problems in FL within the metaverse. Finally, we outline some future research directions of HFL in the metaverse.

[Introduction] Femtosecond laser direct inscription is a technique especially useful for prototyping purposes due to its distinctive advantages such as high fabrication accuracy, true 3D processing flexibility, and no need for mold or photomask. In this paper, we demonstrate the design and fabrication of a planar lightwave circuit (PLC) power splitter encoded with waveguide Bragg gratings (WBG) using a femtosecond laser inscription technique for passive optical network (PON) fault localization application. Both the reflected wavelengths and intervals of WBGs can be conveniently tuned. In the experiment, we succeeded in directly inscribing WBGs in 1×4 PLC splitter chips with a wavelength interval of about 4 nm and an adjustable reflectivity of up to 70% in the C-band. The proposed method is suitable for the prototyping of a PLC splitter encoded with WBG for PON fault localization applications.