Mobile Communication Repeater Monitoring Technology in the 3G Era

With the launch of 3G network construction, the monitoring of 3G repeater equipment has also been put on the agenda. At present, the 3G mobile communication industry is gradually moving towards the commercialization stage. As an important device for optimizing mobile communication networks, repeater equipment plays an increasingly significant role in enhancing signal coverage, increasing network transmission speed, and reducing network operation costs. Therefore, its position in mobile communication network coverage has become increasingly important.

China Mobile has conducted practical tests and technical tracking of three 3G mode repeaters, namely WCDMA, CDMA2000 and TD-SCDMA, in some areas. At the same time, the construction of the monitoring network of the repeater has also become a concern of operators and manufacturers. In order to manage all the network elements of the repeater equipment and achieve better real-time network optimization, China Mobile needs to conduct unified and all-weather monitoring and management of all the repeater equipment in its jurisdiction to enhance management efficiency. Moreover, the corresponding network management monitoring system must exist as an independent system in parallel with the repeater equipment system, and its operation must not affect the normal operation of various communication equipment in the network.

Repeater monitoring systems will continue to develop in the direction of networking and digitization. However, with the increasing complexity of application scenarios, the monitoring system has higher and higher requirements for on-site operation. The reliability and stability of the system are becoming more and more important to the entire communication network, so the monitoring requirements for repeaters are also getting higher and higher, such as real-time requirements, anti-interference technology of the monitoring system, reliability verification of data packet transmission, and verification of the correctness of serial port data. Moreover, with the development of current digital image and video compression technology, it has become a trend to transmit video and audio through wireless networks. By using advanced image and video compression algorithms and wireless transmission network solutions, on-site digital image and video data can be transmitted to the monitoring center through wireless Internet to achieve visualization of remote monitoring, thereby guiding the repeater monitoring system into a new stage.

The repeater monitoring system mainly consists of three parts, including the repeater monitoring center (host computer), communication channel and repeater monitoring terminal (slave computer).

Repeater Monitoring Center

The first generation of monitoring centers was designed to meet the needs of production commissioning and network on-site opening. As more and more repeater projects were opened, an effective management method was needed to achieve remote parameter commissioning and alarm reception, and the second generation of monitoring centers came into being. At this time, the monitoring center can achieve basic remote monitoring. At the end of 2001, China Unicom began to build CDMA repeaters on a large scale. While using a large number of repeaters, the daily maintenance and management of repeaters also began to attract the attention of operators due to the increasing maintenance costs, and centralized monitoring became increasingly necessary. Some repeater manufacturers represented by Guoren Communications began to pay attention to the unified network management system, with the aim of providing operators with a centralized solution to monitor the equipment of many manufacturers on the same platform. The third generation of monitoring centers was born, and the system achieved unified network management.

At present, the repeater monitoring center has entered the fourth generation - the integrated network management stage. With the expansion of the construction scale of repeaters and the development of the operator's operation and maintenance model, the network management center with a single machine operation mode can no longer meet the actual operation and maintenance requirements. Therefore, at this stage, the composition structure and functions of the monitoring center have undergone great changes, evolving from a simple stand-alone version of software to a comprehensive system consisting of multiple relatively independent functional parts, and possessing a typical network structure. The monitoring center is composed of a PC and an Internet Short Message Gateway (ISMG). The application software running on the PC completes the database management of each repeater site. ISMG is a short message gateway with short message forwarding function. The monitoring center is connected to the Short Message Service Center (SMSC) through the SMS gateway (ISMG). The short message gateway supports the standard SMPP3.3 protocol and SGI P1.2 protocol, and interacts with the repeater through SMS for control information.

Communication Channel

The data communication between the monitoring center and the monitoring terminal is realized by using the communication channel. The communication channels are divided into direct data communication (point-to-point communication) using RS232 serial port and modem for sending and receiving short messages (Short Message Service, SMS). The direct data communication method has strong real-time performance and fast transmission speed, but its communication cost is high; the SMS method first sends the information to the Short Message Service Center (SMSC), and then the SMS center queues and sends it to each destination in turn. The short message communication method has poor real-time performance and slow communication connection speed, but it has the lowest cost and does not have the problem of occupying channels, so it is currently the main communication method.

There are currently three ways to use (SMS) to achieve data communication.

(1) Access via short message

The repeater and monitoring server are connected via wireless communication links. The built-in modem of the repeater establishes communication with the main server of the monitoring center in the form of short messages. The main server of the repeater uses SMPP or SGIP protocol to communicate with the SMS gateway, and the SMS gateway communicates with the repeater in the form of short messages. The monitoring system of the repeater is connected to the SMS gateway in the form of SP.

(2) Wireless Modem directly connected to the repeater

In the early repeater equipment, some of them communicated by wireless data transmission. Such equipment exchanges data through the central server of the repeater centralized monitoring system and the wireless modem on the repeater equipment side. When collecting data or monitoring maintenance, it dials up to the repeater side wirelessly to establish a wireless communication connection and realize information exchange. When a fault occurs on the repeater equipment side, the modem on the repeater side dials up to the network management center and sends the alarm information to the network management center.

(3) The wireless modem is connected to the repeater through the front-end device

Some repeaters have their own monitoring terminals locally, which we call front-end processors. These repeaters provide an upper-level network management interface through their front-end processors, and are connected to the central server of the provincial central repeater centralized monitoring system through wireless modems, etc., to achieve monitoring and management of the repeater.

Repeater monitoring terminal

The repeater monitoring terminal is a key part of the entire repeater monitoring system. Its basic functions include configuration management of repeater equipment, real-time data sampling, fault alarm management and remote communication. It is mainly divided into system hardware and system software. The hardware part of the repeater monitoring terminal is mainly composed of the core single-chip processor part, power supply part, external interface part, external expansion part and frequency selection circuit part. The hardware part adopts a modular structure, mainly including multi-channel A/D sampling module, keyboard module, repeater frequency selection part (local oscillator) control module, alarm status indication module, communication module, operation status display module, memory module, power supply module, etc.

The monitoring unit software consists of a main program, several subroutines and interrupt programs. The functions of the monitoring unit software mainly include transplanting the embedded operating system on the microprocessor, developing API (application programming interface) and other functional functions on the constructed software platform, and using the developed API and other functions combined with the programming technology of the operating system to complete the application software writing.

The main program of the lower computer mainly completes the initialization of the serial port, the initialization of the modem, and the initialization of the LCD display module. The timing interrupt program module mainly completes the functions of timing A/D conversion, timing collection of alarm information, timing query of whether there is a key, etc. With the upgrade of the software, the number of parameters that need to be queried is increasing, and the software functions of the monitoring unit are gradually turning from single to diversified, and gradually improving to meet higher requirements and standards.