If the postgraduate entrance examination is exchanged, different universities have different requirements for mathematics, basically one, and a few schools count as two. A * * * take four courses: Mathematics, English, Politics and Specialty. As for what major courses you want to take, you have to go to the website of the school you want to attend. The books reviewed by different schools are different. For the postgraduate entrance examination of communication, most colleges and universities mainly test communication principles and signals and systems (maybe one or two courses at the same time), and some colleges and universities also test others, such as digital signal processing and analog electronic technology. In short, you need to know what school you want to take, and then go to the website of the graduate school of this school to find out which major course you want to take.