Stacked intelligent metasurface (SIM) and dual-polarized SIM (DPSIM) enabled wave-domain signal processing have emerged as promising research directions for offloading baseband digital processing tasks and efficiently simplifying transceiver design. However, existing architectures are limited to employing SIM (DPSIM) for a single communication function, such as precoding or combining. To further enhance the overall performance of SIM (DPSIM)-assisted systems and achieve end-to-end (E2E) joint optimization from the transmitted bitstream to the received bitstream, we propose an SIM (DPSIM)-assisted E2E orthogonal frequency division multiplexing (OFDM) system, in which traditional communication tasks such as channel coding, modulation, precoding, combining, demodulation, and channel decoding are performed synchronously within the electromagnetic (EM) forward propagation. Furthermore, inspired by the idea of abstracting real metasurfaces as hidden layers of a neural network, we propose the EM neural network (EMNN) to enable the control of the E2E OFDM communication system. In addition, transfer learning is introduced into the model training, and a training and deployment framework for the EMNN is designed. Simulation results demonstrate that both SIM-assisted E2E OFDM systems and DPSIM-assisted E2E OFDM systems can achieve robust bitstream transmission under complex channel conditions. Our study highlights the application potential of EMNN and SIM (DPSIM)-assisted E2E OFDM systems in the design of next-generation transceivers.

As the high demand for super-large connection, ultra-broad bandwidth and ultra-low latency of the future 6G mobile communication system, massive MIMO technology is crucial to the future development of IMT industry. The application of space-borne digital phased array antenna makes satellite communication feasible achieving massive MIMO. This paper mainly deals with simulation methodology of satellite- borne phased array antennas. It is appied to such simulations as coexistence, system, link and so on.

In this paper, reconfigurable intelligent surface (RIS) is utilized to enhance the performance of the cooperative non-orthogonal multiple access (C-NOMA). The simultaneous wireless information and power transfer (SWIPT) technology is adopted at the cell-center user to relay information to the cell-edge user. We aim to maximize the data rate of the cell-edge user by jointly optimizing the beamforming vectors, the reflecting phase shifts, the power splitting (PS) ratio and the relaying power under the energy constraint and minimum data rate constraint of the cell-center user. To solve the established non-convex problem, an iterative algorithm based on alternate optimization is proposed to decompose the original problem into three sub-problems. In addition, successive convex approximation (SCA) and semi-definite relaxation (SDR) techniques are also employed to solve the sub-problems. Simulation results illustrate that the proposed RIS-assisted cooperative SWIPT NOMA scheme can effectively improve the performance of the cell-edge user compared with the traditional scheme without RIS.

Carrier aggregation is one of the important areas in 5G stand-alone (SA) networking deployment plan, which is of great value for improving user experience. In 5G SA networking deployment, there are technical and implementation challenges when carrier aggregation is combined with Massive MIMO (Multiple-Input Multiple Output). Based on the principle of two MIMO beamforming methods, the performance differences of the methods are analyzed and compared. Then, the field test verifies and obtains the measured performance difference. Finally, the estimated peak rate ranges of the carrier aggregation UEs with different beamforming modes are given.

As the basic strategic resource of wireless communication, spectrum is crucial to the development of both IMT industry and satellite communication. In order to promote spectrum utilization and better develop the IMT system, WRC-23 1.2 issues are deliberating to identify frequency bands for future development of International Mobile Telecommunications (IMT),5G and 6G,including the possibility of making additional divisions for mobile services as the main business. This paper mainly deals with the study of co-channel interference of IMT system to the Earth exploration satellite service (EESS) (active) in 10-10.5 GHz frequency band. As a result of study, IMT system and EESS(active) can sharing this frequency band.

5G is the focus of global communication technology research, the important engine to improve the level of the national economy and informatization. With the commercial deployment of 5G network, more and more research institutions and related personnel begin to research on the net generation mobile communication system –6G. In wireless communication systems, compared with FDD, TDD technology does not require paired spectrum resources, which is more suitable for current and future wireless communication heterogeneous networks with asymmetric uplink and downlink diversified data streams. However, in a system using TDD technology, cells with different traffic conditions will use different uplink and downlink configurations, which will introduce cross-slot interference between cells and affect the improvement of system throughput. For example, indoor scenarios, especially industrial Internet scenarios for large-scale applications in the future, have a relatively high proportion of uplink services, and the same TDD timeslot ratio, which is adopted in outdoor scenarios, cannot meet the service requirements in industrial scenarios. Therefore, it is necessay to study the interference situation when using different TDD configurations in indoor and outdoor scenarios to provide a reference for TDD unsynchronized interference management in mobile communication systems.

The Non-Terrestrial Network (NTN) is composed of satellite systems, high altitude platform base stations, low altitude platform stations and so on. The NTN network plays an important role in the ubiquitous and intelligent connection to all things on earth for 6G system. Meanwhile, the use of High-Altitude Platform Stations (HAPS) as IMT Base Stations (HIBS) is a significant part in the NTN network. HIBS has the advantages of wide coverage, flexible deployment, low delay and low construction cost, and attracts the attention of many international organizations and countries. In order to promote the specification of HIBS, ITU-R WRC-19 had resolved to identify WRC-23 Agenda Item 1.4: study the use of HIBS in the mobile service in certain frequency bands below 2.7 GHz already identified for IMT. This paper is based on WRC-23 AI 1.4, and focus on the frequency band 900MHz which has better wide coverage characteristics. Considering the spectrum refinement on the terrestrial network, from 2G/3G to 4G in suburban and rural areas, this paper focus on the sharing and compatibility study between HIBS and 4G LTE system.

Multiple input multiple output (MIMO) technology has been considered as one of the essential technologies to enhance the performance of Long Term Evolution (LTE) system with the limited bandwidth and transmit power. For indoor coverage, it is difficult to implement MIMO technology since the challenges of engineering and cost in doubling the number of installed antennas and feeders. Therefore, two indoor MIMO distributed antenna system (DAS) solutions are proposed by using frequency converting and signal comibing and separating by upgrading the existing indoor DASs. Frequency converting is employed to decrease the carrier frequency of LTE system when it is higher than 2500MHz since most of the existing feeders can only support the frequency of the transmit signals from 800MHz to 2500MHz. In the proposed schemes, two branches' MIMO signals can be loaded into the feeder of the existing DAS by combining them together after converting the original LTE frequency into two different lower frequency bands, and a dual-polarized indoor antenna is used at remote site to reduce the number of antenna locations. Some simulations show the effect of difference on transmit power and time delay between two LTE MIMO branches. Our field measurement results reveal that the proposed schemes can provide the comparable level of performance but more simpler and pratical to be deployed.