The verification result shows that, compared with static RIS that can only improve fixed-point coverage, base station and dynamic RIS collaborative beamforming technology can not only greatly increase the coverage capability of base stations, but also support users’ seamless connectivity even during movement.
The research and development of both parties in the field of RIS has entered into the second phase of dynamic collaboration between base stations and RIS.
In 2021, both parties accomplished prototype verification of the first phase of the RIS technology, and initially explored its feasibility to improve fixed-point coverage in 5G blind spots and weak areas. In 2022, China Mobile Research Institute and ZTE continued to explore the RIS technology, and jointly accomplished the research and development of the dynamic RIS prototype with the collaborative beamforming capability, and accomplished the industry's first technical verification in the laboratory and field environment respectively.
The Reconfigurable Intelligent metaSurface (RIS) technology, a cross-border collaboration between electromagnetic meta-materials and modern wireless communication technology, uses programmable new sub-wavelength two-dimensional meta-materials, actively regulates electromagnetic waves through digital codes, and configures different phase offset parameters between different array elements to implement beamforming of electromagnetic waves. The first phase of RIS is static metaSurface, which can improve signal fixed-point coverage, but there are some problems, such as inability of beam direction adjustment, poor coverage capability, and engineering deployment difficulty. The joint project team innovatively proposed the dynamic collaboration technology between 5G base station and dynamic RIS. The key of this technology is that 5G base stations send beam ID and other information to the dynamic RIS through the air interface, so as to guide the RIS to dynamically select and switch beams, and implement dynamic beam scanning and beam tracking. This solution applies the key 6G technology of RIS into 5G network.
In the lab verification, three test points were selected to perform fixed-point coverage and rate tests respectively under the conditions of no RIS and dynamic RIS deployment. The test result shows that the coverage and user rate of the dynamic RIS are greatly increased for three points, the maximum RSRP is increased by 27 dB, and the user rate is increased by 5.4 times. In addition, during the user movement, the reflective beam of dynamic RIS can accurately track a user in a timely manner, with stable signal strength and rate.
In field test, the fixed-point coverage before and after dynamic RIS applications and coverage and rate tests under mobile scenarios are performed. The test results show that the dynamic RIS brings great gains in the test area, the maximum RSRP is increased by 23 dB, and the user rate is increased by five times.
The field test results in Shanghai lab and field show that the new dynamic RIS collaboration technology can greatly improve the coverage capability and engineering deployment flexibility, compared with the static RIS technology. Also, it provides a low-cost, low-power consumption, and scientific and feasible innovation path for the in-depth coverage of 5G networks and future network evolution, laying profound technical foundation for the future commercial use of RIS technologies.
Moving forward, China Mobile and ZTE will work further with global industrial partners to conduct in-depth research on system design and collaborative algorithms, expecting to continuously promote the evolution of RIS technologies.