Research Area
Sourced from RF wireless world (https://www.rfwireless-world.com/Terminology/Difference-between-5G-and-6G.html, accessed May 20, 2020)
Wireless communications
Recently, a wireless system is a fusion of variety of fields of techniques including smart factory, smart city, internet of things, intelligent systems, autonomous driving, personal health cares, cellular networks, and etc. Such wireless systems will be governed by appropriate wireless communication techniques to transfer information between any two elements of them. Thus, 5G and 6G wirelss communications are considering special methodologies to manage and optimize the wireless networks such as those described in the figure at the left, and our lab. are mainly interested in developing various type of wireless communication techniques and systems to improve such converged wireless networks. Specific topics include machine learning applications to communications, multiple-input and multiple-output (MIMO) systems, milli-meter wave communications, signal processing techniques involving finite bit ADCs
Machine learning applications
Machine learning, and the corresponding deep learning techniques have attracted a tremendous amount of interest in various research fields, recently, after Alpha-Go was introduced by Google. Deep learning also has various applications to wireless communications. For example, we are applying reinforcement learning to improve detection performance of MIMO receiver which overcomes bad effects from imperfect channel estimation (see the figure right above). We are also considering to apply learning techniques for beam selection problems of massive MIMO systems and user selection problems of multi-user MIMO systems. Moreover, machine learning techniques are very suitable to autonomously optimize and manage a huge wireless network. In this case, intelligent systems based on AI techniques can also be considered.
Communication algorithms
Massive MIMO
Ideally, multiple-input and multiple-output (MIMO) schemes can construct multiple independent wireless channels by implementing multiple antennas at both sides of the transmitter and receiver. Massive MIMO tries to maximize such benefits by increasing the number of antennas without a limit. However, in practice, many degrading parameters disturb us from achieving the ideal benefits, and we must overcome such limitations to obtain an expected performance of Massive MIMO schemes in beyond 5G communications
Millimeter wave
The most fundamental resources for communication are time and frequency. Especially, frequency resource has been exhausted around frequency bands applied to cellular systems. People have tried to find a new resource to increase communication capacity. The MIMO scheme is an example in this regard, which exploits a spatial resource. In 5G communications, we intend to use frequency bands in millimeter wave, which has not been used for cellular systems. If we can develop a stable wireless communication system using millimeter wave, every performance will be greatly improved.
Finite bit ADCs
Finite bit ADCs use a few bits to quantize real-valued received signal. Because the detection performance decreases with the number of quantization bits, it gives up some performance to obtain simplicity in receiving structure. Especially, 1 bit ADCs have attracted much attentions recently as it can greatly simply RF circuits without losing much performance when the SNR is relatively low. As the use of a 1 bit ADC completely changes communication structure, the performance achieved by it must be carefully examine in future wireless communication systems.