Space Division Multiple Access Technology SDMA

This technology divides the space into different channels, so as to realize the reuse of frequencies and achieve the purpose of channel capacity expansion. For example, using multiple antennas on a satellite, the beams of each antenna are directed to earth stations in different areas on the ground in different areas of the earth's surface, and they operate at the same time, even if they use the same frequency. will interfere. The processing procedure of the SDMA system is as follows:

1. The system will first snapshot or sample the signal from all antennas, then convert it to digital form and store it in memory.

2. The SDMA processor in the computer will immediately analyze the sample, evaluate the wireless environment, and confirm the user, interference source and location.

3. The processor calculates the combination of the antenna signals, and strives to restore the user's signal optimally. With this strategy, each user's signal reception quality is improved, while other users' signals or interfering signals are blocked.

4. The system performs analog calculation, so that the antenna array can selectively send signals to the space. Again on this basis, each user's signal can be efficiently transmitted through a separate communication channel space-space channel.

5. On the basis of the above processing, the system can send and receive signals on each spatial channel, so that these signals are called bidirectional channels.

Using the above process, the SDMA system can create a large number of frequency-division, time-division or code-division bidirectional spatial channels on a common channel, and no channel can fully deduct the gain and anti-jamming functions of the entire array. Theoretically, an array with m elements can support m spatial channels per common lane. However, the number of channels supported in practical applications will be slightly lower, depending on the environment. It can be seen that the SDMA system can double the system capacity, so that the system can support more users in a limited spectrum, thereby multiplying the efficiency of spectrum use.

Since September 2011, wireless communication has undergone major changes from analog to digital and from fixed to mobile in recent decades. As far as mobile communication is concerned, in order to make more effective use of limited radio frequency resources, time division multiple access (TDMA), frequency division multiple access (FDMA), and code division multiple access (CDMA) have been widely used, and On this basis, two major mobile communication networks, GSM and CDMA (narrowband CDMA different from 3G), are established. As far as technology is concerned, these three existing multiple access technologies have been fully applied, and the efficiency of spectrum usage has been brought to the limit. Spatial division multiple access technology (SDMA) breaks through the traditional three-dimensional thinking mode. On the basis of traditional three-dimensional technology, it greatly broadens the use of spectrum in the fourth-dimensional space. The use of mobile users is only due to different spatial locations. It is possible to reuse the same traditional physical channel and introduce mobile communication technology into a newer field.