  The 5th wireless communication (5G) techniques not only fulfil the
requirement of $1,000$ times increase of internet traffic in the next decade,
but also offer the underlying technologies to the entire industry and ecology
for internet of everything. Compared to the existing mobile communication
techniques, 5G techniques are more-widely applicable and the corresponding
system design is more complicated. The resurgence of artificial intelligence
(AI) techniques offers as an alternative option, which is possibly superior
over traditional ideas and performance. Typical and potential research
directions to which AI can make promising contributions need to be identified,
evaluated, and investigated. To this end, this overview paper first combs
through several promising research directions of AI for 5G, based on the
understanding of the 5G key techniques. Also, the paper devotes itself in
providing design paradigms including 5G network optimization, optimal resource
allocation, 5G physical layer unified acceleration, end-to-end physical layer
joint optimization, and so on.
