In the CDMA system, since it is a dynamic network, the change of the cell changes correspondingly with changes in the user and the business situation, which causes a respiratory effect phenomenon of the cell. At the same time, the location of the users in the network and the mobility characteristics of the users also inevitably result in the near-far effect caused by the proximity of the user's location in the network. The CDMA network is completely different from the GSM network. Since the channel and the user are no longer considered separately, there is no difference between the traditional coverage and the capacity. The larger the traffic of a cell, the smaller the cell area. Because the increase in traffic in a CDMA network means an increase in interference. The effect of this dynamic change in cell area is called cell breathing. It can be illustrated by the example of the image. There are many guests in a room, and the more people who speak at the same time, the harder it is to hear the voice of the dialogue party. If you can start talking to an acquaintance at the other end of the room, you can't understand the other person's words when the noise in the room reaches a certain level. This shows that the cell radius of the talk area has been reduced. Through this, we can see that when planning for the network, we are faced with a dynamically changing network. When planning a CDMA network, we must first consider the scalability of the network. We cannot simply add the frequency to the relevant cells as we planned the GSM network. In the initial stage of network planning, a certain signal margin must be considered. When calculating the cell area, it is a compensation for interference caused by an increase in traffic. This means that it is necessary to build a network with a smaller cell or more base stations from the beginning, which also means an increase in investment costs. If the traffic signal margin is set too small, it can only be solved by building more base stations. We must note that if the above problem is caused, if the transmission power is increased unilaterally, the deterioration of the received signal due to the increase in traffic cannot be solved. The increase of the transmit power can only improve the received signal of a certain cell, and the cost is to increase the interference to all neighboring cells, thereby affecting the communication quality of the entire network. Moreover, increasing the transmission power cannot extend the effective coverage or capacity of the CDMA cell indefinitely. When the transmission power is doubled for a CDMA network, the capacity of the cell is only increased by about 10%. Although the increase of the transmit power increases the effective coverage of the cell, in order to meet the needs of the remote mobile phone users, the transmit power must be increased in proportion, which inevitably affects the call quality of other mobile phone users. The correspondence between transmit power and cell capacity is gradual, so we must reduce the network's full load rate. The specific parameters of the load saturation of the cell depend on various services, and of course the risks that the network operator is willing to bear. Generally speaking, when designing a network, the full load factor is preset to 60%. This is also reflected in the network planning and design in the early stage of network construction. When designing through planning and design software, the concept of 60% load is usually entered. It is consistent. In this case, the respiratory effect of the cell is applied, and the adjacent cells can compensate each other for the load capacity, which we call soft load. Due to cost reasons, we cannot increase the capacity of the network on a large scale. For CDMA services with high data transmission capacity in the future, the probability that the serving cell borrows the load capacity from the neighboring cell increases with the increase of the data transmission amount. The phenomenon that the coverage of a cell varies with the intensity of the service in the area is the so-called "breathing effect". Since the strength of the CDMA network varies randomly in the area, the "breathing effect" always exists, because this effect will be formed due to the contraction of the cell. "Overwrite vulnerability", that is, blind zone, so you should pay attention to this problem when planning your network. In the respiratory effect, there may be questions about the effects of respiratory effects on the repeater. Usually, since the output power of the repeater is constant, the "breathing effect" does not affect the output power, but it will affect the coverage. In the application of respiratory effects, it is also necessary to note that the breathing effect is usually accompanied by the switching problem, so we should pay attention to the setting of the size of the switching area while paying attention to the breathing effect. If the switching area is too large, the access time will be inevitable. Long, poor paging response time, and even dropped calls. If the switching area is too small, an "overlay vulnerability" may occur. So in the respiratory effect problem we have to study together with the switching problem. In the CDMA system, another typical problem is the "near-far effect" phenomenon, because all users in the same cell share the same frequency, so it is extremely important for the entire system to transmit signals with minimum power for the entire system. As long as there is a person shouting in the room, it will hinder the communication of other guests. This problem can be solved by adjusting the power in a CDMA network. But we will also encounter another situation of this problem. When a user is away from the base station, a large part of the transmission power must be obtained, so that the power supplied to other users is in short supply. This means that the cell capacity is related to the actual distribution of the user. When the user density is large, the statistical average can be used to solve the problem. When the number of users is small, the network must be dynamically analyzed by simulation. As far as the near-far effect problem is concerned, as with the respiratory effect, since the user's unfixability is always present, in a certain sense, the near-far effect problem also affects the capacity of the system. Adding a call to the system means that the user is causing interference to other users, and power control is needed to overcome the interference caused by the user. When the process is increased to an insurmountable power, a new call cannot be initiated. At this time, the capacity of the system has reached the "limit". Of course, the voice activity will also affect the adjustment of power control, and power control affects the capacity of the system, so we can also say that the capacity of the CDMA system is a soft capacity. In many respects, CDMA systems have advantages that other systems cannot match. At present, network optimization needs to be further improved, so that the advantages of CDMA networks can be fully utilized. This requires us to analyze and solve the problems found in the process of optimizing the network, sum up the experience, and provide a more reliable basis for the future network construction optimization. xiaojuzizhi Ganzhou Green days Biochemical Technology Shower folder mechanic Co., Ltd. , https://www.cn-gangdao.com