New Solution for Vehicle-mounted GPS/GPRS/CDMA System

With the continuous deepening of my country's economic reform and the gradual establishment of a market economy system, various transportation undertakings such as highway construction and road transportation are developing by leaps and bounds. In order to achieve a series of goals such as further managing the transportation market and ensuring transportation safety, transportation departments at all levels are actively promoting "intelligent transportation": that is, a new type of information-based, intelligent, and socialized transportation formed by transforming traditional transportation systems through the use of advanced information, communication, control and other high-tech technologies.

After installing the vehicle-mounted GPS satellite positioning system on long-distance buses, tourist buses, and dangerous goods transport vehicles, the central monitoring system can monitor the vehicles in real time, which has a positive auxiliary management role in supervising the drivers' speeding and fatigue driving, and improving the level of transportation production organization; at the same time, the monitoring center can implement the alarm function for long-distance operating vehicles that are in speeding, breaking down, etc., thereby reducing the incidence of traffic accidents and improving transportation safety production. At present, the vehicle-mounted GPS system has been recognized by relevant management departments and enterprises and is being actively promoted and applied.

Longren Research Institute is a high-tech research institute specializing in VOIP and wireless data communications. The institute has launched a series of GPRS wireless communication products to the market. In combination with the latest vehicle-mounted GPS technology, it has launched a new generation of full-IP network vehicle-mounted GPS monitoring and transmission system. The innovative use of GPRS TCP/IP data communication plus SMS backup has replaced the past communication method that relied entirely on SMS to transmit data, and has a high overall performance-price ratio.

Analysis of existing vehicle-mounted GPS text messaging system

Figure 1 Schematic diagram of existing vehicle-mounted GPS SMS system

The existing vehicle-mounted GPS SMS system communication is mainly implemented by GSM SMS, and its typical applications are as follows:

1. Technical features of existing GPS SMS solutions

The vehicle-mounted GPS information machine collects and processes the vehicle's location information collected in real time by the GPS device.

The vehicle-mounted GPS information device sends the processed information to the corresponding SP or designated mobile phone number of the transportation management monitoring center via SMS at a regular interval.

The transportation management monitoring center receives the corresponding vehicle GPS information through SP or designated mobile phone number.

In special cases, the operation management monitoring center can directly send text messages through SP or designated mobile phone numbers to control the vehicle GPS system, such as warning or forced shutdown.

2. Disadvantages of existing GPS SMS solutions

Uncertain transmission time: Because text messages are transmitted using channel command time slots and there is no dedicated data channel, data transmission delays or losses are likely to occur when the command time slot is busy.

The channel capacity is limited: a text message can transmit a maximum of 140 valid bytes, which cannot fully and timely reflect the real-time information of the vehicle.

Communication costs are expensive: basically calculated based on the total number of messages sent and received.

Poor scalability: With SMS as the main communication link, due to the link bandwidth, it is impossible to further expand other data transmission services in the future, such as image monitoring during vehicle operation.

Although the vehicle-mounted GPS monitoring system is conducive to the transportation department to realize intelligent traffic management, the overall performance of the current SMS method is poor, which hinders the full promotion of the system.

GPRS Development Status and Technical Analysis

GPRS (General Packet Radio Service) is a new packet switching data application service developed on the existing GSM network. GPRS is the mainstream technology and important milestone in the evolution of global mobile communication network technology to the third generation mobile communication (3G), and is known as 2.5 generation mobile communication. Compared with the traditional GSM circuit dial-up exchange, GPRS has a qualitative leap in resource utilization efficiency, exchange capacity and performance. GPRS abandons the traditional exclusive circuit exchange mode and adopts packet exchange technology. Each user can occupy multiple wireless channels at the same time, and the same wireless channel can be shared by multiple users, effectively utilizing channel resources, and the bandwidth can reach up to 171.2Kb/s. At present, China Mobile's GPRS coverage has reached almost 100% in central cities and more than 80% in remote areas. The actual application bandwidth is about 20-40Kb/s, which is particularly suitable for various medium and low-speed burst communication needs in industries such as financial transactions and remote monitoring, and completely replaces the traditional wired MODEM, X.25, data transmission radio, SMS and other communication methods in the past.

GPRS uses TCP/IP protocol and is very easy to integrate with existing INTERNET technology and application platforms. It will combine various IP technologies and services with mobile communication technology to provide customers with various high-speed and high-quality mobile vehicle data communication services.

Figure 2 GPRS network structure diagram

Advantages of GPRS data transmission

(1) Mobile communications: GPRS wireless communications have broken the fixed location limitations of past wired communications. Data transmission points can be increased or decreased at any time according to business needs, greatly expanding the scope of communications.

(2) Low cost: The GPRS network charges customers based on the data traffic of the data packets they send and receive, rather than charging based on the number of text messages as SMS does, which greatly reduces the cost of communication. For example, for the GPS monitoring system, the communication fee for the same service is about 1/5 to 1/8 of the past, which has strong cost competitiveness and marketability. Currently, China Mobile has also launched a preferential policy of 900 yuan per year without data usage.

(3) Always online: The client stays connected to the network at all times. Even when there is no data transmission, the client still maintains a connection between the network and the client.

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(4) Fast login: The connection time is very fast. As soon as the GPRS wireless terminal is turned on, it has established a connection with the GPRS network. Each time you log in to the network, you only need an activation process, which usually takes only 1 to 3 seconds.

(5) High-speed transmission: Since the GPRS network adopts advanced packet switching technology, the theoretical maximum data transmission rate can reach 171.2 kb/s. In actual use, it can generally reach 20 to 40 kb/s.

(6) Flexible networking: China Mobile's GPRS network has a wide coverage area and can roam across the country without any additional charges. It is particularly suitable for small and medium-sized users to build their own cross-regional data network in a short period of time at a low cost.

(7) Channel guarantee: GPRS communication links are maintained by professional operators such as China Mobile. In the event of a communication link interruption, they can be repaired in a timely manner, eliminating the worries of communication link maintenance.

(8) Lightning protection: GPRS uses a low-power short antenna and does not require a large antenna to be installed outdoors, thus overcoming the problem that wired transmission equipment and radio stations are easily damaged and communication interrupted by lightning strikes.

GPRS Wireless Data Communication Product Introduction

GPRS/CDMA dedicated data terminal is a new type of wireless mobile communication network equipment that integrates data collection, analysis and processing functions, GPRSMODEM transmission functions and TCP/IP network functions. It implements the complete PPP protocol and upper layer TCP/IP protocol, so that non-IP systems can access the Internet and Intranet through simple serial port communication.

Figure 3 Schematic diagram of the internal functions of a GPRS/CDMA dedicated data terminal

Key features:

Data analysis and processing: Calculation and processing can be performed according to the requirements of business data collection equipment; such as weighted average calculation of GPS positioning information, etc.

Wireless IP transmission function: The GPRS/CDMA dedicated data terminal has a complete TCP/IP protocol stack embedded in it, which can encapsulate data into IP frames and then transmit them to the GPRS network through the wireless module. Most traditional data terminal devices (such as GPS devices) generally do not have IP functions, but can easily connect to the Internet through the GPRS/CDMA dedicated data terminal.

SMS backup function: Use the GSM network SMS channel as a backup link for the GPRS network link. When the GPRS network link fails, it can automatically switch to the SMS backup link, effectively ensuring the reliable transmission of key information.

Friendly management interface: Configuration management is carried out through the embedded Web Server, which is very intuitive, simple and convenient to operate. It supports remote maintenance and can realize remote configuration, remote upgrade and restart according to management authority.

Figure 4 Friendly product configuration interface

New GPRS Solution for Vehicle-mounted GPS System

After an in-depth analysis of the existing vehicle-mounted GPS SMS system, we believe that a convenient, cost-effective, always-online, and stable communication method can effectively solve the huge cost of vehicle-mounted GPS monitoring systems in communication transmission, and is a necessary means for the widespread promotion of vehicle-mounted GPS monitoring systems in the transportation industry. China Mobile's GPRS network is a new communication method that meets this demand. At the same time, using the original SMS as a backup link can fully guarantee the real-time and reliability of GPS monitoring system data transmission, and at the same time, there is a qualitative leap in performance and price. Its networking method is as follows:

Figure 5 Schematic diagram of the new GPRS solution for vehicle-mounted GPS system

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1. Main features

Low communication cost: The communication characteristics of the vehicle-mounted GPS monitoring system are bursty, but the data volume is small, which is very advantageous to the GPRS that uses traffic-based metering. Taking a GPS information transmission as an example, the minimum cost of using short messages is 0.10 yuan per message. Using GPRS, the cost is reduced to 1 to 2 cents, which is reduced by more than 80%, which is very cost-effective.

High data transmission efficiency: GPRS is a new type of mobile data communication service that provides high-speed wireless IP services to mobile users. The location information collected by the GPS device is analyzed and processed, and then encapsulated in IP messages for transmission. Its maximum data transmission efficiency is >90%.

Strong and favorable security measures: The GPRS network adopts GSM's multiple physical channel encryption methods. At the same time, at the application layer, it also provides security measures such as central dedicated line access and dedicated APN, which can fully meet the security scalability requirements of the transportation management system.

Strong scalability: New monitoring content can be added on GPRS according to future business needs, such as image transmission, etc.

Optional SMS backup: In the case of GPRS failure, the traditional SMS backup method can be used to ensure the transmission of key information.

2. Data Center Introduction

The operation management monitoring center is connected to the Internet. The GPRS network is connected to the Internet through the mobile bureau GGSN, thereby realizing the networking communication between the GPS monitoring system and the data center.

The monitoring center can be connected to the Internet using ADSL, PSTN, dedicated line and other communication modes. Users can flexibly choose according to their needs and cost issues.

3. Introduction to vehicle-mounted GPS system

The vehicle-mounted GPS system includes a GPS locator and a GPRS/CDMA dedicated data terminal. The GPS locator and the GPRS/CDMA dedicated data terminal are connected via a serial port.

GPS instruments collect location coordinate information through satellite positioning systems;

The GPS instrument transmits the location information to the GPRS/CDMA dedicated data terminal through the serial port;

GPRS/CDMA dedicated data terminal completes the analysis and processing of coordinate information;

The GPRS/CDMA dedicated data terminal sends the processed serial port data to the GPRS network in the form of TCP/UDP data frames.

Table 1 Comparison table of GPRS solutions for vehicle-mounted GPS systems and other methods

To sum up, we believe that the new GPRS solution of vehicle-mounted GPS system will be gradually promoted and implemented in current traffic management, and will create good social and economic benefits.