What are the classification and advantages and disadvantages of mobile communication networks?

Classification of mobile communication networks

Mobile communication networks according to the nature of the business of telephone services and data, fax and other non-talking services; according to the object of service there are public mobile communications, dedicated mobile communications; according to the scope of activities of the mobile station there are land mobile communications, maritime mobile communications and aeronautical mobile communications; according to the use of the points, commonly used cell phones, wireless paging, trunked dispatching systems, leakage Cable communication system, cordless phones, no center addressing mobile communication system, satellite mobile communication system, personal communication.

Disadvantages of mobile communication networks

(1) Mobility

It is to keep the object in the moving state of the communication, and therefore it must be wireless communication, or the combination of wireless and wired communication.

(2)Complex conditions of wave propagation

Because the mobile body may move in a variety of environments, electromagnetic wave propagation will produce reflection, refraction, bypassing, Doppler effect and other phenomena, resulting in multipath interference, signal propagation delays and broadening and other effects.

(3) serious noise and interference

In the urban environment of automobile spark noise, a variety of industrial noise, intermodulation interference between mobile users, neighboring channel interference, same-frequency interference and so on.

(4) The system and network structure is complex.

It is a multi-user communication system and network, must make the users do not interfere with each other, can work in a coordinated manner. In addition, the mobile communication system should also be interconnected with the municipal telephone network, satellite communication network, data network, etc., the whole network structure is very complex.

(5) requires high band utilization and good equipment performance.

Mobile communication network advantages

1. Large system capacity. In the CDMA system all users *** with a wireless channel, when some users do not speak, all other users in the channel will be due to reduced interference and benefit.CDMA digital mobile communication system capacity is theoretically 20 times larger than the analog network, in fact, 10 times larger than the analog network than the GSM 4 to 5 times larger.

2. Good communication quality. CDMA system uses adaptive threshold technology to determine the rate of the vocoder, high-performance error correction coding, soft switching technology and anti-Multi-Path Fading Diversity Receiving technology, can provide TDMA system can not be compared to the very high quality of communication.

3. High bandwidth utilization, CDMA is a spread spectrum communication technology, although the spread spectrum communication system to improve the anti-jamming performance is to occupy the bandwidth at the expense of the bandwidth, but the CDMA allows a single band can be reused throughout the entire system area, so that many users **** with this band at the same time call, greatly improving the bandwidth utilization. This spread-spectrum CDMA method takes up a wider band, but its band utilization is high based on the average band occupied by each user.

4. Applicable to multimedia communication system: CDMA system can easily use multi-channel mode and multi-frame mode to transmit multimedia service information with different rate requirements, and the processing and synthesizing modes are more flexible and simple than TDMA and FDMA modes, which is conducive to the application of multimedia communication system.

5. Low transmitter power of cellular phone: CDMA system can minimize the transmitter power of CDMA cellular phone through power control, in order to reduce the interference and improve the network capacity.

6. Flexible frequency planning. Users are differentiated by different code sequences, sectors are differentiated by different guide codes, and the same CDMA carrier can be used in neighboring cells, so the frequency planning of CDMA network is flexible and easy to expand.