Network planning and remediation process and program analysis for GSM networks in small and medium-sized cities

The proportion of small and medium-sized cities in China has reached 60% to 70%. The scale of GSM network users also has an absolute advantage. The problems of network quality, resource utilization and operation efficiency in GSM networks in small and medium-sized cities are similar. The optimization ideas and implementation methods are universal. This paper summarizes the characteristics of GSM networks in small and medium-sized cities, and gives the network planning and remediation process and methods.

Before planning and rectifying a city's network, first collect and analyze the geographic features, network size, population, users and other data of the city, and understand the technical parameters of the wireless devices and antennas used, and familiarize with the entire network. Background, operating conditions, etc.

Secondly, the GSM network should be rectified through the following key steps: collecting and analyzing the network data, and testing the network areas with problems in a targeted manner; conducting on-site investigation and finding problems; performing comprehensive positioning analysis on the discovered problems, and formulating optimization plans Implementation plan; evaluate the network after the implementation of the optimization; finally evaluate whether the optimization goal is achieved, and if the target is not met, continue to analyze and formulate a new optimization plan.

This process mainly analyzes the network in the relevant area, mainly including network operation data and network test data. The network operation data includes traffic statistics and user complaint data.

In the process of analyzing network data, the station with high drop rate, high blocking rate and call success rate, and low handover success rate are counted, and combined with user complaint information for nearly half a year, the base station with possible problems or The community and the areas and buildings that require operators to conduct road tests and dial tests.

The network test data is mainly the DT and CQT data of the operators for the above-mentioned test areas and real estate. These data are sampled and tested by using test equipment, which can more specifically reflect the current situation of the specific location of the network, and have absolute absolute for post-planning and rectification work. Supporting role.

Planners check the situation of these stations and their surrounding sites on the previously identified problem base stations and communities, and analyze the status of the base station antenna feeder to understand its azimuth, downtilt angle, antenna hanging height, coverage environment, etc., based on the initial judgment of the site environment. Possible problems with a single site.

The following situations are typical problems that often occur.

Some antenna antennas have a downtilt angle of the antenna 5 to 6 meters higher than the surrounding environment. It is obvious that the antenna cannot cover the area covered by the antenna well, and the coverage may occur. As shown in Figure 1.

Some base station antennas are hung up to the same height as the surrounding floors, and some base station antennas are blocked by new buildings and cannot be well covered.

After obtaining sufficient data, planners need to analyze the network and base station in detail. According to the intensity of user complaints, some small areas can be divided within the scope of planning and rectification. Combining complaint information, DT, CQT data and on-site inspection information, the base stations related to these small areas are analyzed, and the problems are analyzed in a targeted manner. The cause of these problems is to fully consider the operation of a certain base station, but also to consider the situation of the surrounding base stations and the impact of the wave-transmission environment near the small areas. These base stations are coordinated and adjusted together to avoid "stretching." "The situation has arisen.

The general rectification plan includes: switching parameter adjustment, antenna feed adjustment, planning macro station, planning room sub-system, etc., wherein the antenna feeder system adjustment can be divided into azimuth adjustment, downtilt adjustment, antenna height adjustment, antenna position adjustment, antenna. Parameter adjustment, etc.

Switch the adjustment of the parameters. The cell switching flow direction is adjusted according to the road test result, the cell location, and the traffic distribution. A cell switching has a certain ratio of cut-in and cut-out, and 20%-80% of the cuts are normal, and the system needs to be adjusted too low or too high. Under the condition that the switching threshold is defined correctly, the insufficient number of channels is the main reason for the low switching success rate. The adjustment method is to increase the number of channels, change the corresponding parameter to divide the traffic, or add a microcell base station.

The antenna is hung up and adjusted. In the initial stage of construction of the GSM network, there are fewer stations. In order to ensure coverage, the base station antennas are generally erected higher. In recent years, the number of base station sites has increased significantly, and in many urban areas of small and medium-sized cities, it has reached a station of about 500m. In this case, the coverage of the base station must be reduced, and the height of the antenna must be reduced. Otherwise, the network quality will be seriously affected, resulting in unbalanced traffic, intra-system interference, and islanding effects.

Antenna azimuth adjustment. In general, planners are not in favor of adjusting the azimuth of the antenna, as this may cause some degree of intra-system interference. However, in some special cases, such as local emergency meetings or large-scale public events, the traffic volume of some communities is particularly concentrated. It is necessary for the network optimization personnel to adjust the antenna azimuth to achieve the purpose of balancing traffic and optimizing the network. For some signal blind spots or weak areas in the suburbs, the network can also be optimized by adjusting the azimuth of the antenna.

Antenna downtilt adjustment. The adjustment of the antenna pitch angle is the key to network optimization. Choosing a suitable pitch angle can make the antenna with the antenna to the boundary of the cell boundary and the ray of the antenna to the boundary of the victim cell in the portion where the gain attenuation changes the most in the vertical direction of the antenna, so that the same frequency and adjacent frequency interference of the interfered cell Minimize; in addition, select the appropriate coverage so that the actual coverage of the base station is the same as the expected design range, while enhancing the signal strength of the coverage area.

Antenna position adjustment. Due to the late engineering, traffic distribution and changes in the wireless propagation environment, it is difficult for the GSM base station to improve the local area coverage or even cause unnecessary interference by the above method, and the base station needs to be relocated and relocated.

Planning a macro station. For network coverage vulnerabilities and network congestion in urban areas, it is necessary to increase the carrier capacity, introduce D networks, or add new base stations.

Planning an indoor distribution system. As an auxiliary coverage method, it can solve the coverage of some large buildings, basements, etc. that are responsible for the structure.

After formulating the plan and rectification plan according to various situations, the planners mark the rectification content and let the operator's engineering personnel enter the actual operation stage.

After the network rectification plan, it is necessary to evaluate the rectification effect in time to see if the expected purpose has been achieved, whether the original problem has been solved, and whether it has a negative impact. Based on the results of the assessment, it may be necessary to correct the original plan before implementation.

The network rectification plan presented in this paper combines the content of planning and local optimization, so that the operator can rectify the regional site of the existing network problem on the one hand, and plan the new urban area on the other hand.