In the early 1990s, it was said that Apple, Motorola, and other companies gave a presentation to the FCC (Federal Communications Commission), which manages the frequency assignment in the USA, to acquire a new frequency band for wireless LANs (Local Area Networks). In the presentation, they showed a future built by wireless LAN technology, that is, children and teachers in schools would use tablet devices for their educational activities, and medical personnel in hospitals would also utilize the devices for their medical activities. Soon after, the frequency band of 5 GHz band was assigned to wireless LAN systems and that future in part has become a reality.

Unexpectedly, the COVID-19 pandemic accelerated the realization of the future and demanded the further development of remote communications technologies. In the COVID-19 pandemic and post-COVID-19 era, the penetration of telework will increase opportunities for video conferencing using wireless LANs at home. Aside from this, the “GIGA school’’ concept in Japan, that is, one mobile device per person, will also increase opportunities for video viewing and video conferencing on mobile devices in schools.

In such an environment, wireless communications technologies that enable high-quality video transmission to multiple mobile terminals are required. On the other hand, mobile terminals have limitations in terms of the number of antennas, battery capacity, computing power, etc. Therefore, a technology is required that can realize high-quality video playback even on relatively less powerful mobile terminals.

In this paper, the authors propose an information transmission technology that can transmit high-quality video to multiple mobile terminals using wireless LAN technologies. The proposed method consists of the following three components: 1) a method to protect visually important information encoded by SVC (Scalable Video Coding), 2) an E-SDM (Eigenbeam Spatial Division Multiplexing) method applicable to communication systems where the number of antennas of mobile terminals is smaller than that of antennas of access points, which is known as overloaded MU-MIMO (Multi-User Multiple-Input Multiple-Output) systems, and 3) a receiver technology with reduced computational complexity corresponding to the aforementioned transmission technology. In this paper, it is shown that the proposed method can achieve acceptable video quality with 1/5 of the required receiving power and 1/3 of the computational complexity compared with existing techniques.

To come up with the proposed method, it is necessary to be familiar with multiple technical fields, such as, source coding, channel coding, wireless communication systems, and signal processing, and to make a great deal of effort. In this sense, this paper perfectly suits the IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences which cover interdisciplinary research. The efforts of publishing this paper should be honored.

This paper can contribute to the realization of high-quality video transmission using wireless LANs required both for the COVID-19 pandemic and the post-COVID-19 era, and to the enhancement of the value of IEICE transactions. For the above reasons, this paper can be highly evaluated as a paper worthy of the Best Paper Award.