Networking scheme based on 3G wireless IP network

In the emergency state, the mobile cluster base station can rapidly expand the communication coverage or increase the network capacity of the event occurrence location. Since the wireless link is highly mobile and convenient to open, it becomes the best choice for the mobile base station networking. This paper analyzes and compares the advantages and disadvantages of using microwave, satellite and 3G networks as clustered mobile base station networking links according to the needs of the units. It concludes that the 3G wireless IP network networking method is superior to other methods, and then explains the specific implementation. Method and introduce the actual use of the method.

In recent years, TETRA manufacturers represented by Motorola have been widely recognized by the public security, transportation, enterprises and government users in the Chinese market. After the successful support of the Beijing Olympics, the armed police forces have promoted construction. The mobile cluster base station can strengthen and complement the blindness of the signal strength or the sudden occurrence of the event, and realize where the cluster network responds quickly. It is a necessary supplement for the construction of a fixed cluster network for public safety users. Generally, the TETRA base station uses the TDM link to connect to the network. The telecommunication carrier generally provides the TDM framing transmission service only in the backbone network. The mobile base station is difficult to access the operator's existing TDM transmission network by using the normal connection mode. How to realize the rapid and stable networking of mobile base stations has become one of the urgent problems for cluster builders.

Mobile cluster base station networking uses microwaves or satellite links, but these two methods have obvious shortcomings (see Table 1 for details).

It can be seen from Table 1 that the microwave and satellite equipment are bulky, difficult to carry on the vehicle, and difficult to deploy; the electromagnetic waves of the 3G network have a certain penetration capability, the equipment is small in size, low in cost, and can be stably operated for a long time, and the advantages are obvious. The problem is that the end of the 3G network adopts the TCP/IP protocol, and the cluster base station based on the TDM transmission cannot directly access, but needs to perform transmission protocol conversion.

The relevant personnel of the Communications Department of the Armed Police Hainan Corps proposed a TDM line solution based on 3G wireless IP network.

Basic principle: using a protocol conversion device to complete the mutual conversion between the IP network data packet and the private network TDM frame structure data; adjusting the parameters of the mobile base station and the 3G device, so that the cluster networking device adapts to the wireless network transmission delay and implements the mobile The cluster base station is interconnected with a fixed cluster network.

Implementation conditions: The base station has 3G wireless network coverage, and the telecom operator opens a VPN dedicated channel between the WCDMA wireless DTU and the PCM aggregation device. One integrated communication vehicle equipped with a cluster base station, two RAD IPMUX units, and one 3G wireless Internet access device (with SIM card).

Equipment connection plan:

Install Unicom WCDMA wireless DTU equipment on the integrated communication vehicle, adopt WCDMA VPDN technology, and build a VPN dedicated channel between WCDMA wireless DTU and PCM aggregation equipment; between mobile cluster base station and wireless DTU equipment, WCDMA APN equipment and PCM multiplexing equipment ( Between the MUXs, a protocol conversion device is installed to enable the in-vehicle cluster base station to access the PCM device and finally access the Virtual Chassis Center (MSO). The device connection scheme is shown in Figure 1: