PHS (即小灵通) communication system adopts TDD, 32-bit ADPCM transmission mode, one carrier frequency in PHS system is divided into 8 time slots. Its operating frequency is: 1895 ~ 1918MHz, the frequency interval is 300KHz.

The frequency utilization rate of the PHS system is high, so the system capacity is large, which reduces the transmit power of the mobile station and prolongs the battery life. The PHS system adopts Dynamic Channel Assignment (动态信道分配) technology, supports automatic roaming and handover of mobile phones, and can automatically complete authentication and encryption. The confidentiality and anti-theft capabilities of the phone are greatly improved, and the mobile speed is up to 40Km/h. PHS systems are inexpensive and can add new functions to switching equipment. The terminals of the PHS system are mobile stations and mobile phones, which can not only transmit voice, but also have the incomparable advantages of other wireless products in terms of data transmission. In addition, its transmit power is only 10mW on average and has obvious advantages compared with other systems. It is a good supplement to the local telephone network business and is getting more and more attention.