Space Laser Communications for Beyond 5G/6G

Advanced communication networks in Beyond 5G and 6G are expected to realize seamless connections between terrestrial and non-terrestrial networks. Beyond 5G and 6G will require further global spatial expansion of the network exceeding that of the current 5G, whose direction is toward not only two-dimensional expansion so far but also three-dimensional expansion for non-terrestrial networks in the future. Recently, many mega-constellation systems have been planned and launched from various countries. Although the frequency spectra will soon be exhausted, space laser communications have potentially wider bandwidths in the optical spectrum with smaller and lower-power-consumption onboard equipment, and are a viable alternative. Because optical communications do not have regulatory restrictions or licensing issues, they can revolutionize the space system architecture. This paper introduces the trend and future vision of the space laser communication technology in the Beyond 5G and 6G era.