GPRS Wireless parameter Analysis

As a mobile communication system, the setting of parameters related to wireless devices and interfaces in GSM network is very important to the service performance of the network, such as the coverage of the community, the distribution of signaling traffic, and the business performances of the network. GPRS technology provides a packet data service for GSM network, it has its own independent wireless parameter setting which differs from the ordinary GSM network. According to the wireless parameters in the Network Service object, generally can be divided into two categories, one for engineering parameters, the other is the resource parameters. Engineering parameters refer to the parameters related to engineering design, installation and opening, such as antenna gain, cable loss and so on, these parameters must be determined in the network design generally, it is difficult to change in the process of network operation. Resource parameters refer to the configuration of wireless resources and the use of related parameters, which are typically routed over the wireless interface (UM) to maintain consistency between the base station and the mobile station. Another important feature of resource parameters is that most resource parameters can be dynamically adjusted through a certain Man-machine interface during the operation of the network. In this paper, we will try to analyze the definition and setup of some important wireless resource parameters which are related to GPRS. These parameters can be divided into two kinds: system control parameters and cell selection parameters according to their function.

System control Parameters

Network working mode (NMO, network mode of Operation) is an important system control parameter, according to the network to the circuit business and the packet Service paging way and its coordination relationship can be divided into three kinds of work mode, the network work mode setting reflects the network ability, At the same time, it also puts forward the requirement of the mobile station capability. The mobile station chooses the work level that suits its ability according to the setting of the network working mode. In addition, the network working mode can affect the process of attaching and routing area updating. For example, the network operating mode is Ⅰ, then class A and Class B Mobile station can do joint location and routing area update, if the network working mode is Ⅱ and Ⅲ, then the mobile station should do the location update and routing area update respectively, thus, under the condition of permitting, the network work mode should be set as the mode Ⅰ, Can save the wireless resources of the network to a great extent. Setting the network working mode requires that the NMO values be the same within the same routing area. (Computer science)

Access level control parameters (access control class) can be used to prevent access requests from all or part of the mobile station in certain special areas. For example, there is a state of emergency in some areas or a network that has a serious failure, and so on. Each ordinary user has an access level. The access level is divided into 10 categories, rank 0 to Level 9, and they are stored in the mobile user's SIM card. For some special users, there are 5 special access levels, that is, level 11 to level 15. These levels usually have a higher access priority. Special users can also have one or more access levels (between 11~15), and their access levels are also stored in the user's SIM card. The allocation of access levels is as follows:

Grade 0~9: ordinary users;

Level 11: For the management of PLMN;

Level 12: Security sector applications;

Level 13: Utility sector (e.g. water, gas, etc.);

Level 14: Emergency services;

Grade 15:PLMN staff.

Access level for 11~15 users than the access level of 0~9 users have higher access priority, but between the access level 0~9 and between the access level 11~15, the size of the access level does not indicate the level of access priority.

The access level control parameters are composed of 16 bits, respectively c0~c15, corresponding to 15 access levels in the form of bit mapping (where C10 Express emergency call permission).　　A bit of 0 means that the mobile station with the corresponding access level is not allowed to access the local area, otherwise, the access is allowed. Cell selection parameters when the mobile station is switched on, a suitable community will be selected and stay there to contact the network. This selection process is called "Community selection". The so-called right community is limited by many factors, if the community is the choice of the network (in the artificial network selection mode), whether the community is prohibited access, the priority of the community, mobile station access level is prohibited by the community and the quality of the wireless channel to meet the needs of communications and so on. The quality of wireless channel is an important factor in the selection of the community. In the GSM specification, a parameter is called the path loss criterion C1, the so-called suitable community must ensure the c1>0 of the community.

Mobile Station after the selection of the community, in a variety of conditions do not occur major changes in the case, mobile station will stay in the selected community, while the mobile station began to measure the vicinity of the BCCH carrier signal level, recording one of the largest signal level of the 6 adjacent communities, and from which each of the adjacent cell system message and control information. When a certain condition is met, the mobile station will be transferred from the current stop to another community, this process is called the district re-election. The so-called certain conditions include many factors, such as the priority of the community, whether the community is prohibited access and so on. One of the important factors is the quality of the wireless channel, when the vicinity of the signal quality over the area will cause the re-election of the community.

Conclusion

As can be seen from the above analysis, according to the actual wireless channel characteristics, traffic characteristics and traffic load, the corresponding wireless parameters can be set up to improve the communication quality, regulate the distribution of the network, make full use of the network wireless resources, improve the average service performance of the network and improve the utilization rate of the equipment. Increase the capacity and average service level of the entire system.