[0003] 1. Due to the limitations of geographical location (ocean, desert and hills, etc.), environmental protection and rights protection (commercial and residential quarters and cultural relics protection areas, etc.), and station construction conditions (electric power, iron towers, transmission, funds, etc.), it is impossible to solve the communication problem through the new station Coverage hole problem
[0004] 2. Since the wireless terminal equipment is limited by small antenna size, battery capacity, transmission power, etc., the terminal (for land mobile communication network can be mobile phone or wireless network card, etc., for satellite communication can be a transponder) to the main station (for land mobile communication network, it can be a transponder) The mobile communication network is called a base station, and it can be a ground station for satellite communication) The transmission link is a weak link, and its performance is far lower than the link performance from the main station to the terminal, that is, there is an imbalance between the uplink and downlink. The weak link determines the coverage and communication quality of the network, and becomes a bottleneck for realizing a high-performance network system
[0005] 3. At present, the number of various main stations and terminal equipment is increasing day by day, wireless communication frequency resources are tight, the frequency of spectrum used is getting higher and higher, the propagation characteristics are getting worse and worse, the distance between main stations is getting closer and closer, intranet and competition network The frequency pollution caused by interference and other interference is becoming more and more serious, which reduces the signal-to-noise ratio of the signal received by the main station and seriously affects the communication coverage, communication quality and system capacity.
[0006] 4. In the CDMA (Code Division Multiple Access) system, there is self-interference between code channels, which produces a breathing effect. In addition, various wireless interference and soft handover that require 30% fixed channel overhead often make the system Working capacity does not reach 60% of theoretical capacity
[0009] 1. There is no receiver for all existing equipment, and it is impossible to have a radio frequency bandpass filter with extremely steep receiving filter characteristics, extremely small insertion loss, small fluctuations in the wide-pass frequency band, and a rectangular coefficient close to 1 with traditional technology. Effectively filter out the interference outside the passband (stopband), and reduce the intermodulation interference caused by these interferences entering the receiver, which improves the system noise floor
[0010] 2. All the above-mentioned devices amplify the received signal and noise at the same time, and the noise is accumulated on the receiving link instead of weakened. The result is that the quality of the received signal is getting worse and worse
[0011] 3. The low-noise amplifiers of the RF front-end of the receiver of all the above-mentioned devices work at room temperature. Due to the thermal noise generated by the electronic Brownian motion, the amplifier amplifies the noise generated by itself, which raises the bottom noise of the system and deteriorates the signal-to-noise ratio
Seriously affect communication coverage and quality and capacity
[0012] 4. Where the communication coverage and quality are not good, it is often due to network planning, unreasonable master station layout (such as high density of land mobile communication base stations, frequent cell switching or unreasonable coverage and frequency planning, etc.), pilot pollution and various In areas with severe interference, increasing the master station, frequency configuration and equipment configuration in these areas is often a large amount of investment, but it will cause further interference and frequency pollution, increase system and maintenance costs, and further reduce resource utilization such as frequency and equipment.
In fact, most sources of interference and faults in the network come from tower amplifiers, repeaters and indoor distribution systems, which seriously pollute the network environment
[0013] 5. Since factors such as available resources, internal and external interference, and changes in business demand are uncontrollable, using the above-mentioned methods and technologies to solve problems will always be a passive fix.
[0014] To sum up, the use of existing traditional technical means and equipment cannot fundamentally solve the problems of: removing external interference and intermodulation interference; reducing the bottom noise of the system itself; effectively improving the gain and sensitivity of useful signals