3g Wireless network optimization

3G Network optimization has the same side with 2G network optimization, but also has its special aspects, so this paper mainly from 2G to analyze the 3G network optimization, mainly for reference to the 2G network optimization experience to the 3G wireless network optimization analysis.

First, Introduction

Because the mobile communication system is influenced by the objective environment, with the continuous expansion of the system and the change of the external environment, many new problems often arise, which leads to the quality of service not being up to the standard. In this way, the huge investment is not fully utilized, but also affects the reputation of the system operations department. Therefore, how to adjust and optimize the system structure, improve the operating efficiency of the system, improve the service quality of the mobile phone system is an important task of wireless network optimization.

When the operators are ready to build a 3G mobile communication network, they must first design the system according to the geographic environment, traffic forecast and the characteristics of the wireless channel, including the network topology design, the base station location and the PN (or scrambling code) planning and so on. However, compared with the fixed system, because the user terminal in mobile communication is mobile, it has strong fluidity, suddenness and randomness whether it is traffic volume or signaling flow or some other network characteristic parameters. These characteristics determine the mobile communication system design and the actual situation in the traffic model, signaling flow and so on generally there is a big difference. Therefore, when the network is running, the operators need to adjust the network structure, configuration and parameters to make the network work more rationally. This is an important part of the whole network optimization work. (Computer science)

Second, the focus of the different stages of network optimization

The so-called network optimization, is according to the actual performance of the system, the actual performance of the system, the system analysis, on the basis of the analysis of the system parameters, the system performance is gradually improved, the existing system configuration to provide the best quality of service, that is, the optimal coverage, satisfactory signal strength, The best call quality and the lowest drop rate.

In the general sense, optimization is the process of making the system reach the best state by means of all kinds of technology, and adjusting the unreasonable part of the system in the condition of fully understanding the system operation. The optimization of mobile communication system is very important because its user position is not fixed, and the wireless signal is susceptible to environmental influence.

According to the function of optimization in mobile system from opening to normal operation, network optimization can be divided into two different types: Engineering optimization and maintenance optimization. The former in the system just opened or at the end of each expansion, the main role is to solve the construction of the remaining problems may exist and new equipment installed after the installation of the original system has a negative impact. Therefore, the engineering optimization is mainly to carry out the work of clearing the net, this is a relatively primary level of optimization; the latter is during the stable operation of the system, due to the increase in the number of users, the external environment changes will lead to the deterioration of the system, in addition, as the operation of the maintenance personnel on the system of continuous in-depth understanding, Will find some unreasonable elements in the system. Therefore, the maintenance optimization is a higher level of the system optimization, the purpose is to improve the operating efficiency of the system, need to be optimized by the cycle.

Three, 3G wireless network optimization cycle and process

1. 3G Wireless network optimization cycle

From the network to mature business, 3G network optimization generally go through three stages, that is, the network planning and design phase, network construction and network commercial and mature stage. The tasks of network optimization in each phase are different, Figure 1 gives the focus of optimization in different periods.

2. 3G Wireless network optimization process

From the experience of domestic CDMA network optimization and the experience of 3G operation in foreign countries, the optimization process of 3G network can be started from following several stages.

(1) Verification

A Verify all information related to wireless in the database: including site coordinates, structure type, antenna position, antenna hanging height, antenna type, antenna azimuth, antenna pitch angle, feeder/jumper type, output power, ce quantity, E1 quantity, etc.

B Check the base station, check the RF information, verify the installation of the equipment and should meet the conditions: including antenna positioning, day feeder measurement, to ensure that all the relevant RF signal is properly handled.

(2) Network test

A The test route should include all major roads, hot spots and areas with high traffic volume, and the route spacing should be between 400~800 meters. The north-south and east-west main roads and highways should be tested in two directions.

B The test should be done using a mobile phone and sweep receiver to collect data. The sweep receiver should be used with GPS so that the signal can be unlocked on the correct pilot frequency. As the sweep receiver data does not depend on the activation of the network or the processing of the call (including the neighborhood list, switching, activation settings size, search window, etc.), it can reveal problems in the RF (for example, PN is not in the Search window, the same area has more than six pilot signals, etc.).

C After processing the road test data, mainly includes the following performance measurement indicators: RSSI, MTX (mobile phone transmission power), FER (WCDMA for the Bler value), Ec/io, also includes some through the sweep receiver and mobile phone collection of other performance measurement indicators: The strongest service pilot, the number of active pilot frequency, The best pilot ec/io, larger than the activation set threshold of the number of pilot, the strongest ec,ec in -80dbm above the pilot number, the strongest two pilot frequency Ec/io difference.

D Regional Road survey data and standard deviation are mainly used to analyze and calculate the performance indexes of 4 cores: RSSI, MTX, FER (Bler), Ec/io. In addition, regional road test data and standard deviations are also used to compute the region's drop-and-fail access (excluding the weekend's two-week period). These statistical values and road test data can be used as a benchmark for regional optimization.

(3) Sector positioning

A Identify all potential problem points through road test data: including high fer (Bler), low Ec/io (Total and best), low rssi, high MTX, higher than the t-add of the pilot too much (note that WCDMA uses a relative threshold, that is, in different communities or different noise environments, Add or remove effective concentration of the cell pilot's absolute threshold is related to the effective concentration of the last pilot and the weakest pilot signal intensity, rather than in advance, the EC is better than the -80dbm of the pilot too much, have dropped, access failure phenomenon.

B Use sector statistics to arrange all sectors in terms of drop rate and access failure rates.

C Use the above data for optimization.

(4) Base Station survey

A Check the problem area to see if it is caused by a wireless environment. The problematic sectors are positioned by means of the road test data (EC and Ec/io for each pilot). In some cases, signaling information and CDL files can also be used to analyze the causes of the dropped words.

B The characteristics of the problem area: Wireless cover cavity, pilot-frequency pollution, pilot-frequency emergent (strong pilot-frequency interference), Edge sector (network edge overlay and switching problem), neighborhood list problem, potential antenna problem, high traffic problem, fan area breathing problem.

C Sometimes, some wireless problems are caused by the device. For example, the day feeder problem can cause performance degradation, bad MCC or CE will cause high fer. Pilot EC and pilot Ec/io can help to check the problem of antenna feeder problems or fan-sector-connected (2-sector antennas emitting 1-sector pilot frequencies). Due to the MCC or CE problem, the typical characteristics of high fer are good ec/io, good mtx, good rssi, poor Fer (greater than 10%, usually close to 25%~100%).

(5) Monitoring to facilitate the day-to-day optimization of work after system changes

For the system that has been put into operation, the number of users has reached a certain scale, the traffic volume has a certain growth, that is, the system runs under the load conditions, at this time the data obtained from the system test can reflect the actual operation of the system more realistically. The Daily network optimization under the condition of system load can be divided into 3 steps: Network fault diagnosis monitoring, network optimization test and network optimization data analysis.

In the practical work, the network optimization of CDMA system is a continuous and repetitive process. It is necessary to analyze the data collected in the process of network optimization, modify the parameters of the system, then collect and analyze the data, then revise the parameters of the system, so that the system can run more and more reasonable. In order to maintain the optimal performance of the system, the system parameters have to be adjusted according to the situation because of the constant change of the ground structure. So network optimization is a regular, essential work.