Introduction Environmental monitoring departments, as the technical departments of the national environmental protection system, are an important foundation for environmental management. With the increasing environmental awareness of citizens, more and more people are concerned about the quality of their environment and demand transparency in environmental protection work; higher-level authorities also require a large quantity, variety, and rapid update of information. All of this raises a crucial question for environmental monitoring departments: how to establish a practical, comprehensive, and flexible environmental data collection system to meet the needs of all parties for environmental monitoring information? The rapid development of GPRS/CDMA/EDGE wireless networks provides an excellent solution for environmental monitoring. Introduction to GPRS/CDMA/EDGE Wireless Networks : GPRS (General Packet Radio Service) is essentially an intermediate technology for the transition from second-generation mobile communication technology (GSM) to third-generation mobile communication (3G). It was first proposed by BT Cellnet in the UK in 1993 and is one of the contents of the GSM Phase 2+ (1997) specification. Fundamentally, it is still a mobile packet data service based on GSM, providing users with mobile packet IP or X.25 connections. GPRS is a new network superimposed on the existing GSM network. It involves adding hardware and upgrading the original software to form a new logical network entity. GPRS provides users with end-to-end, wide-area wireless IP connectivity. In simple terms, GPRS is a high-speed wireless data transmission technology based on packet switching. Users can use GPRS while on the move to access various high-speed data services, including sending and receiving emails, browsing the Internet, and instant messaging. CDMA Introduction: CDMA (Code Division Multiple Access) is a new wireless communication technology developed from spread spectrum communication technology. The principle of CDMA technology is based on spread spectrum technology. The information data with a certain signal bandwidth is modulated with a high-speed pseudo-random code with a bandwidth much larger than the signal bandwidth, thus expanding the bandwidth of the original data signal. This is then carrier-modulated and transmitted. The receiving end uses the exact same pseudo-random code to perform correlation processing with the received bandwidth signal, converting the wideband signal back into the narrowband signal of the original information data—a process known as despreading—to achieve data transmission. The standardization of CDMA technology has gone through several stages. IS95 was the first standard released in the CDMAONE series. The first CDMA standard to achieve widespread global adoption was IS95A, which supported 8K coded voice services. When the ITU solicited candidate technologies for third-generation mobile communication from various countries, the US TR45 standards committee, having just achieved commercial success with IS95, did not focus much on third-generation standard research, but instead worked on completing the IS95B standard. At the ITU's request, the third-generation standard CDMA2000 was proposed that year, namely CDMA2000 1X and 3X (1X representing a carrier bandwidth twice that of IS95A, and 3X representing a carrier bandwidth three times that of IS95A). 3X was further divided into downlink direct spread spectrum and three-carrier methods. Later, the direct spread spectrum portion of CDMA2000 was merged with WCDMA, so the current CDMA2000 actually only includes CDMA2000 1X and the three-carrier 3X method. CDMA 1X refers to the first phase of CDMA 2000 (speed higher than IS95, lower than 2 Mbit/s), supporting data transmission at 308 kbit/s, introducing packet switching in the network portion, and supporting mobile IP services. It is a new bearer service developed on the existing CDMA IS95 system, aiming to provide CDMA users with packet IP data services. The GPRS system uses the existing GSM wireless network. GPRS and GSM share the same base stations and spectrum resources, only requiring some hardware and software upgrades on the existing GSM network. Therefore, upgrading from GSM to GPRS is very easy, and China Mobile, leveraging its existing GSM network, has very wide GPRS coverage. Currently, China Mobile's GPRS network covers all provinces, municipalities, and autonomous regions nationwide, spanning over 240 cities. CDMA is based on spread spectrum technology and occupies the entirely new 800MHz frequency band (GSM occupies the 900MHz band), so it cannot be directly upgraded on existing GSM equipment. Currently, China Unicom has optimized and upgraded its CDMA network through the second phase of construction, upgrading it from IS95 to CDMA1X; simultaneously, it has built a wireless data network covering 31 provinces (autonomous regions and municipalities) nationwide. EDGE Introduction: EDGE stands for Enhanced Data rate for GSM Evolution. This technology primarily enables broadband services, allowing networks using the 800, 900, 1800, and 1900MHz frequency bands to provide some functions of third-generation mobile communication networks, and significantly improves the standardized services currently provided on GSM and TDMA/136. This technology can provide 384kbps wide-area data communication services and approximately 2Mbps local-area data communication services, thus fully meeting the bandwidth requirements of future wireless multimedia applications. The concept of EDGE was first proposed to ETSI by Ericsson in 1997. In the same year, ETSI approved the feasibility study for EDGE, paving the way for its future development. Although EDGE still uses GSM carrier bandwidth and time slot structure, it can also be used with other cellular communication systems. EDGE can be considered an effective universal radio interface technology that provides high bit rates and thus facilitates the evolution of cellular mobile systems towards third-generation functionality. Based on this, the Unified Wireless Communications Forum (UWCC) evaluated EDGE technology for TDMA/136 and approved it in January 1998. EDGE provides a transitional solution from GPRS to third-generation mobile communication, allowing existing network operators to maximize the use of existing wireless network equipment and provide users with personal multimedia communication services before the commercialization of third-generation mobile networks. Because EDGE is a transitional technology between existing second-generation and third-generation mobile networks, it is sometimes referred to as a "2.5G" technology. EDGE also makes full use of existing GSM resources, protecting investments in GSM, and most existing equipment can continue to be used in EDGE. EDGE offers three service sets: EGPRS: maximum speed ≥384kbps (48kbps/BP); T-ECSD: transparent enhanced circuit-switched service, maximum speed ≥32kbps/BP; NT-ECSD: non-transparent enhanced circuit-switched service, maximum speed ≥28.8kbps. Introduction to Wireless Network-Based Environmental Protection Monitoring Systems In environmental protection systems, real-time monitoring of numerous pollution emission points is often required, and most monitoring data needs to be sent to the backend server of the management center for processing in real time. Due to the dispersed and wide distribution of monitoring points, and the fact that most are located in harsh environments, transmitting data via telephone lines is often inefficient. Data transmission via GPRS/CDMA/EDGE wireless networks has become one of the communication methods chosen by environmental protection departments. Pollution source monitoring equipment can simultaneously send collected pollution data and alarm information to multiple environmental monitoring departments via GPRS/CDMA/EDGE wireless networks, enabling timely management of polluting units or individuals and greatly improving the work efficiency of environmental protection departments. System Components The wireless network environmental protection monitoring system mainly consists of three parts: the environmental monitoring terminal system, the wireless data transmission network platform, and the environmental monitoring management center system. The environmental monitoring terminal system comprises various water pollution monitors, air pollution monitors, noise pollution monitors, and wireless transmission terminal equipment. The wireless data transmission network platform utilizes current domestic public wireless networks such as GPRS, CDMA1X, or EDGE. The environmental monitoring management center system includes a network communication server, a real-time database server, and a user control interface. Physical Connection Structure The environmental monitoring terminal equipment is physically connected to the wireless transmission terminal via RS232/RS485/RS422/TTL or Ethernet interfaces. The environmental monitoring management center accesses the IP network via ISP (Internet Service Provider) leased lines/fiber optics/wireless connections. Working Principle ** Active Data Reporting Method:** The environmental monitoring terminal system collects real-time information on water, air, and noise through a physical interface and transmits it to a wireless transmission terminal. The wireless transmission terminal encapsulates the monitoring information into TCP/IP packets and sends them to multiple designated environmental monitoring and management center IP addresses. Upon receiving the monitoring information, the environmental monitoring and management center stores it in a database and displays the monitoring station status in real-time on its software interface. **Center-Based Interaction Method:** The environmental monitoring and management center uses user application software to issue data collection commands to the online environmental monitoring terminal equipment for data collection and control. Remote control is possible for exceeding emission standards and malicious emissions. The active data reporting method and the center-based interaction method can coexist in the application, enabling the entire system to perform telemetry, remote signaling, and remote control functions. ** System Advantages :** Low investment, convenient and quick networking, multiple environmental monitoring departments can simultaneously monitor monitoring stations, good data real-time performance, and simple system maintenance. **Application Areas: ** Emission control of industrial waste, sewage treatment plants, urban environmental pollution control, and nearshore marine pollution control.