Detailed explanation of GSM wireless network optimization Parameter Adjustment

How many of us understand the GSM technology that often appears in wireless networks? Here we will show you how to adjust parameters for GSM wireless network optimization.

Wireless resource parameters mainly include network identification parameters, system control parameters, cell selection parameters, and network function parameters. Network identification parameters are mainly used for identification between mobile platforms and networks. system control parameters mainly refer to parameters related to system configuration. Cell selection parameters mainly refer to parameters related to cell selection and Cell Reselection for mobile stations; network function parameters mainly refer to parameters related to various system functions.

GSM wireless network optimization 1. Prerequisite and type for Parameter Adjustment

1.1 prerequisites

Network Optimization personnel must first have a deep understanding of the meaning, adjustment methods, and adjustment results of Various wireless parameters, and have considerable experience in the wireless parameter types involved in network problems. On the other hand, the adjustment of wireless parameters will depend on a large amount of actual measured data during network operation. Generally, these parameters can be obtained through two methods: one is to obtain statistical data in the Operation and Maintenance Center of the network, such as the CCCH channel bearer, the RACH channel bearer, and the other, such as residential coverage and MS communication quality, which must be measured and tested. When adjusting Wireless Parameters to solve the problem, you must ensure that the device is not faulty. You must perform regular data collection and measurement for the region where the parameter needs to be adjusted; parameters must be adjusted to consider the impact on adjacent coverage areas.

1.2 type

According to the nature of the wireless parameter adjustment, the problem can be divided into two categories.

The first type is to solve static problems. That is to say, by measuring the average traffic volume and traffic volume of each area of the network, the traffic model used in the system design is corrected to solve the common phenomenon that has existed for a long time; another type of adjustment is used to solve traffic overload and channel congestion in some regions during a certain period of time due to some emergencies or random events.

For the first type of situations, network maintenance engineers only need to regularly measure and summarize the actual network operation conditions, and make appropriate adjustments to global or local network parameter configurations. In another case, network optimizers adjust some Wireless Parameters in real time based on the real-time data obtained by the surveyors.

GSM wireless network optimization 2. Parameter Adjustment Method

The GSM system is a standardized system determined by the European Telecommunications Standardization commission. Most of the parameters are strictly defined in the GSM specification. However, in the development process of various manufacturers, many parameter settings for optimizing the network are added based on their own experience. Or adjust the standard parameters to adapt to the protocols of your devices.

The following describes how to adjust data parameters in BSC.

2.1 relationship between neighboring communities

The cell measurement frequency must be the BCCH frequency of the adjacent cell. Too many or too few measurement frequency points will affect the measurement performance. The parameters for switching between adjacent cells must meet the requirements of signal field strength, time amount, signal quality, and corresponding algorithms. Adjust the definition of adjacent cells based on the field strength test diagram and traffic volume distribution. To achieve cross-region switch between BSC, in addition to defining Routing Parameters, you must also define the carrier frequency of the external community, external community, and the base station identification code BISC of the community. Adjust the penalty values of various cross-region switching threshold parameters to change the switching boundary, switching threshold, and avoid the ping-pong switching effect. Cell switch threshold, minimum normal switch interval, minimum switch interval when the switchover fails, improper setting of power control threshold adjustment parameters, or unbalanced residential traffic, adjustments should be made for unnecessary reasons.

2.2 cell parameter adjustment

The adjustment of cell parameters should be coordinated based on various measurement and analysis reports of OMC and BSC, road test results and network test software running results. When adjusting parameters, pay attention to the mutual involvement and influence between parameters.

Adjust the AGBLK and BS-PA-MFRMS In the BCCH/CCCH channel according to the traffic volume of the cell. If the traffic volume of a residential area increases, AGBLK and BS-PA-MFRMS should be added as appropriate. The pre-attenuation parameter BSTXPWR of the peak BTS power should be adjusted for the cell of the base station with high transmit power to reduce the transmit power of the base station and interfere with the adjacent base station. The relationship between BSPWR> BSPWRB, BSTXPWP> BSPWRT should also be satisfied. The indoor coverage of densely populated urban buildings is poor, and the parameter ACCMIN is reduced, which can improve the indoor coverage to a certain extent, but the call quality may decrease, careful trade-offs, trade-offs, and adjustments should be made.

Figure 1 High-Performance Board-zheng'an community software analysis

The solution to the above problems is based on the 4 × 3 Frequency Multiplexing method used by GSM. The frequency points used by the three cells of each base station cannot be the same and cannot be adjacent, in addition, cells that have a switching relationship with adjacent base stations cannot have the same or adjacent frequency points. Therefore, modify the parameters of the Cell 2 or the cell 2, that is, change the frequency point so that there is a neighbor switching relationship between them, but there is no adjacent frequency interference. based on actual experience, generally, the frequency parameter is changed to 2 ~ Avoid interference at three frequency points. After the selected frequency point is adjusted, the above problem can be solved, but you still need to consider whether the selected frequency point is the same as other cell areas of other base stations.

GSM wireless network optimization 3. issues needing attention in Parameter Adjustment

In the GSM system, a large number of wireless parameters are set based on the residential area or local area, while the parameters between regions are usually highly correlated, therefore, when adjusting parameters, you must consider the effect of region Parameter Adjustment on other regions, especially adjacent regions. Otherwise, parameter adjustment will have a strong negative impact.

In addition, when a problem occurs in some areas of the network, you must first determine whether the problem is caused by a device failure (including connection problems). Only when you determine that the problem in the network is indeed caused by business reasons, to adjust the wireless parameters.