Who can talk about the working process of GSM and LTE in a simple and popular way?

GSM: Analog modulation and digital modulation, FSK, BPSK, QPSK, constellation diagram, you know? GSM only uses the most primitive modulation method, while GMSK and 8PSK should, because they have to support many users, and the bandwidth of each user is very small, so the rate is very slow.

WCDMA: As far as I know, he may not have made much progress in modulation. The improvement of the rate mainly depends on the larger bandwidth, so the natural rate is improved. But his key point is that he uses orthogonal codes, and each code is assigned to one user, so the interference between users is very small, so his technical improvement is on multi-users. Although the bandwidth of 5M in GSM is only 20K per person, in CDMA system, the bandwidth of each user is 5M.

LTE:

His core technologies are OFDM and MIMO. OFDM can achieve orthogonality, so it supports many users. The advantages of other OFDM can be Baidu's own. MIMO can provide greater transmission rate and performance, that is, realize multiplexing and diversity, with better natural speed and performance. Just like LTE generally adopts 2* 1 antenna model? I don't remember. Then LTE-A is the antenna model that can achieve 8*4. Both speed and performance are improved by brushing.