Optimization of Wireless Data Transmission System Based on GPRS

Transcription

1 Optimization of Wireless Data Transmission System Based on GPRS Abstract Huiying Shao, Huan Tong, Pei Wang Xingtai Polytechnic College, Xingtai , China In information era, rapid development of communication technology makes daily communication modes of human beings much more diverse and convenient and GPRS undoubtedly provides huge aid to communication business development. Nowadays, GPRS is widely applied in various fields, wireless data transmission system based on GPRS also plays an extremely important role in various fields, and people increasingly concern on performance level of wireless data transmission system based on GPRS as well because of application of various electronic equipment in increasingly complicated people's living environment. Therefore, this paper analyzed the concept, technical characteristics and real-time property of GPRS network technology, discussed the performance optimization design scheme of wireless data transmission system based on GPRS from system structure design, networking scheme design and system transport layer protocol design on this basis and made thorough analysis of key technology of security optimization design of the system, hoping to make a contribution to further performance optimization and improvement of wireless data transmission system based on GPRS. Keywords: GPRS Data Transmission System, General Packet Radio Service (GPRS), Transmission Control Protocol / Internet Protocol (TCP/IP), Point to Point Protocol (PPP). 1. RESEARCH BACKGROUND 1.1 Research overview In recent years, the birth of computer has made the science and technology develop very fast and increasing scientific and technical level also has made China really enter information era. Communication modes of human beings become more and more diverse, from mobile phone to Internet to communication satellite, and our communication becomes more and more convenient thanks to these communication tools. GPRS network technology is the key to realizing the functions of these communication tools. Although there are more and more various data transmission modes, people change their focus to wireless data transmission mode because of geographical limitations, laying line and other difficulties of wire data transmission modes (Hu et al., 2017). Throughout the development history of wireless communication system, speaking of communication modes of Chinese communication system, microwave communication mode, short-wave communication mode and satellite communication mode have successively appeared, and communication systems developed according to these communication modes have advantages and disadvantages. Short-wave and microwave communication modes have the limit of transmission distance and are easily disturbed by surrounding electromagnetic environment and they are more commonly applied in radio and television field; satellite communication mode realizes communication by satellite, costing a lot and limiting its development to some extent (Lu and Li, 2017). With the rise of Internet, GPRS network technology also emerges, and nowadays, mobile communication mode based on GPRS network technology has become the most common and broadest communication means, has wide network coverage and is easier to use, making mobile communication system have far-reaching influence on people s production and living and greatly promoting the development of human civilization (Guo, 2017). 1.2 Research purpose The research purpose of this paper is to find out the best design method, optimize the system performance, overall improve the security, reliability and real-time property of wireless data transmission system, and thus promote the development of China s communication field through discussion on design scheme of wireless data transmission system based on GPRS. Therefore, this paper discussed the concept, characteristics and real-time property of GPRS network technology, built GPRS network delay analysis model, analyzed the optimization design methods 658

2 of structure, networking scheme and transport layer protocol of wireless data transmission system based on GPRS on this basis, and set forth the key technology of optimization design of such system. 2. OVERVIEW OF GPRS NETWORK TECHNOLOGY 2.1 Concept of GPRS network technology GPRS, also known as general packet radio service, is a packet radio switching technology, realizes its function as the core of GSM system, and is to provide users with wide-area and end-to-end wireless IP connection service (Zhao, 2017). GPRS uses the same radio modulation standard, band, burst structure, TMDA frame structure and frequency hopping rules as those of GSM, and its packet data channel is exactly similar to circuit switching service channel so that used base station subsystem can conduct complete GPRS coverage. GPRS network technology can allow users to send, transmit and receive data under end-to-end packet retransmission mode, so to speak, GPRS network technology is a high-efficiency and low-cost data service and particularly applicable to frequent, discontinuous and burst remote data transmission (Tan et al., 2017). 2.2 Characteristics of GPRS network technology GPRS network technology mainly includes the following characteristics. Firstly, wireless data transmission system based on GPRS can carry out 24-hour uninterrupted service. After the system starts, GPRS network will automatically attach GPRS DTU, GPRS data transmission unit, establish corresponding communication link with data center and then can receive data from and send data to equipment. Its real-time property far exceeds that of SMS communication. Secondly, access time of GPRS network technology is very short and its packet switching access time is less than 1s and it can carry out real-time quick connection, thus improving operation efficiency of some services. Thirdly, wireless data transmission system based on GPRS uses charge by traffic. Although it can provide users with 24-hour uninterrupted data reception and transmission service, there is no charge if no data traffic and the charge is calculated and collected according to quantity of reception and transmission of data packet, so that its service cost is far less than cost of WAP service. Fourthly, GPRS network technology has high transmission rate, according to theoretical analysis, GPRS network technology can realize the data transmission rate of 171.2kb/s, but during actual operation process, its actual rate is mainly decided by network settings of operators. According to relevant data statistics, actual transmission rate of GPRS network in China stabilizes 40-60kb/s. Fifthly, GPRS network technology has a wide coverage, wireless data transmission system based on GPRS takes GSM network as basis, carries out packet switching of data through transformation of functional entity and base station of GSM network and can extend the coverage of GPRS network. Sixthly, the networking of GPRS network technology is quite convenient, flexible and simple and needs neither the line erection compared with wired network nor antenna erection compared with wire general network, effectively avoiding approval procedures. Seventhly, communication links built by GPRS network do not need maintenance and are usually maintained by professional operators, for example, communication links for mobile GPRS data service are responsible by Mobile Company, greatly reducing maintenance cost. Eighthly, wireless data transmission system based on GPRS has lightning protection function. This is due to little transmitted power of data transmission unit (GPRS DTU) of GPRS network, and besides, its antenna is short and need not be erected overhead, effectively solving the lightning stroke problem during data transmission process and improving the system security (Wang, 2017). 2.3 Real-time property analysis of GPRS network technology Real-time property analysis of GPRS network directly decides the system usability, so it is very necessary to analyze the real-time property of GPRS network technology. When GPRS transmits data, delay mainly includes air interface delay and network transmission delay. Network transmission delay is decided by transmission delay of fixed transmission network, its transmission speed approaches the speed of light and delay is fixed and can be ignored (Han and Ma, 2016). Air interface delay is main factor affecting real-time property of GPRS network technology and has complex causes of formation, mainly being decided by medium access control protocol and radio link control protocol, which are also known as MAC protocol and RLC protocol respectively. MAC protocol uses Aloha random contention protocol, when GPRS network accesses successfully, different users can reuse and share the same channel, and in case of data transmission error in wireless channel, RLC protocol will retransmit data (Cui et al., 2016). Transmission delay of GPRS network mainly consists of two parts, i.e., from BSS to SGSN, and from SGSN to GGSN. Total delay of GPRS network can be expressed by calculation formula, namely, T total=t 1+T 2+T 3+T 4+T 5+T 6+T 7, where, T 1 represents random access delay, T 2 represents allowable queuing delay, T 3 represents allowable sending delay, T 4 represents the delay of switching to special channel, T 5 represents 659

3 waiting delay when data transmission starts, T 6 represents random data transmission and T 7 represents processing delay (Qi et al., 2016). Because of the limitation of space, this paper only listed the calculation formulas of random access delay and allowable queuing delay. Calculation formula of random access delay is T 1=(L-1)Tc+Td, where, L represents average times when the system sends access request, Tc is related to terminal unit of the system and usually takes 100 ms, and Td represents the time interval produced for the system enters random access request. 1 Calculation formula of allowable queuing delay is T 2=Tb+Pmd1/(2 Umd(1-pmd1)), Umd1 = and Pmd1 = 1, where, Tb represents the BTM processing time. Umd1 (4 framelength) 3. PERFORMANCE OPTIMIZATION DESIGN OF WIRELESS DATA TRANSMISSION SYSTEM BASED ON GPRS 3.1 System structure optimization design In wireless data transmission system based on GPRS, data acquisition equipment can acquire data and transmit data to GPRS DTU via wireless, RS232, USB or RS485 interfaces, GPRS DTU will make these data IP packet when receiving data acquired by data acquisition equipment and then transmit to GPRS network via GPRS air interface, and GPRS network transmits these data to data center via gateway and route (Hou, 2016). Control commands or corresponding data sent by data center can be transmitted to data acquisition equipment via GPRS network. Figure 1 shows the schematic diagram of wireless data transmission system based on GPRS. Figure 1. Schematic Diagram of Wireless Data Transmission System Based on GPRS In Figure 1, data acquisition equipment of the system mainly includes various sensors and cameras. GPRS DTU, GPRS data transmission unit, consists of GPRS transmitting and receiving module, WatchDog circuit, embedded MPU, power module, interface circuit, etc. This system has one data center and multiple data terminals, hence, to realize the connection of data center with multiple data terminals, GPRS DTU of each data terminal shall have matching equipment number (Ma et al., 2016). In addition, port number, APN access mode, IP address and other information of data center shall be clarified, so when install GPRS DTU of data terminal, set the parameter configuration of the equipment in advance. Function of GPRS DTU attaching network mainly includes auto-login, auto check, auto redial, auto dynamic registration of IP address, auto registration of SIM card number, heartbeat packet transmission, etc. of GPRS network. Wireless data transmission system based on GPRS carries out the data packing and unpacking via TCP/IP, and because of complex loading of TCP/IP stack, GPRS DTU of the system selects embedded MPU (Xie et al., 2016). WatchDog circuit of the system can avoid the crash of terminal system and interrupt hardware due to no data reception to realize the auto reboot when the system has crash and other abnormal conditions. Data center of the system consists of main host, database server, networking device, RADIUS server, etc., and its functions are auto access of GPRS network, auto data reception, processing and transmission, auto reception and response of heartbeat packet, database maintenance, as well as authentication of user identity and auto management of other securities of the system. Data center shall have application layer design according to different users of the system (Zhang et al., 2015). 3.2 System networking scheme optimization design System networking scheme optimization design shall be confirmed according to actual needs and application environment of different industries and there are four system networking schemes generally. The first networking scheme is that the data center of the system is connected via Internet public network or ADSL special line and IP or IP+DNS of public network provides resolution services. Apply to the operators for ADSL broadband services 660

4 in advance if using this networking scheme. generally speaking, directly connect the data terminal with data center if public network of data center has static IP, so this scheme is stable, while the stability of IP+DNS resolution scheme is decided by DNS and this scheme is suitable for small-scale application. The second networking scheme is main and ancillary GPRS-DTU scheme and carries out the data analysis by using dynamic IP of Mobile intranet and Mobile DNS. This scheme is suitable for small-scale application only and has poor real-time property and stability, so it is not recommended. The third networking scheme is main and ancillary GPRS-DTU scheme and carries out the data analysis and transmission by using static IP of private APN network. This scheme has the features of no DNS resolution, less middle links, strong stability and reasonable cost performance, so it is recommended. The fourth networking scheme is that system data center is private APN network and all points are static intranet IPs. This scheme can greatly improve the system stability and security and has high comprehensive performance compared with the first three schemes, and it is the best networking scheme if the fund allows. 3.3 System transport layer protocol design Transport layer protocol design of wireless data transmission system based on GPRS can adopt TCP and UDP. TCP has high reliability, strict connection establishment and disconnection procedures, and sliding windows, TCP verification mechanism, retransmission after timeout, and other control mechanisms at the time of message transmission. UCP guarantees reliable system connection via upper layer protocol, has simple design and transmits data faster than TCP, but GPRS network has packet loss sometimes, the system can use TCP can be used in consideration of reliability and UDP in consideration of real-time property (Yang et al., 2014). 4. SECURITY OPTIMIZATION DESIGN OF WIRELESS DATA TRANSMISSION SYSTEM BASED ON GPRS To improve the security of wireless data transmission system based on GPRS, the security optimization design is carried out in two aspects, database and Internet and GPRS. 4.1 Security optimization design of system database There are three security optimization design measures of system database, firstly, use SQL database as data engine; secondly, improve the system security by graduation authorization management; thirdly, improve the system security by perfecting data backup and firewall functions. 4.2 Security optimization design of system Internet and GPRS If using the first scheme, set the system data center in Internet network and out of GPRS subnet and ensure that main host has IP of public network. If using the later three schemes, set the system data center in GPRS subnet and ensure that main host has IP of Mobile intranet. Main host in above schemes has the same functions of general network server and owns two characteristics, that is, firstly, the server client object of main host is known; secondly, main host serves the user servers of GPRS subnet. The following optimization solutions for improvement of system security can be put forward combining two characteristics. Figure 2 shows the schematic diagram of data security technology solution based on GPRS wireless data transmission system. Figure 2. Schematic Diagram of Data Security Technology Solution Based on GPRS Wireless Data Transmission System According to Figure 2, we can see that the optimization solutions mainly include IP filter, ID and password verification, data security encryption channel and access process tracking. 661

5 5. CONCLUSION In conclusion, through analyzing characteristics and real-time property of GPRS network technology of wireless data transmission system based on GPRS, this paper proposed four optimization design schemes and discussed their applicability and security performance optimization design solutions on this basis, hoping to make a contribution to further performance improvement of wireless data transmission system based on GPRS. REFERENCES Cui T.S., Sun J.W., Lv X.C., Zheng T., Meng X.Y., Li X.Y., Lin S. (2016). The irrigation system based on GPRS, The Agricultural Mechanization Research, 38 (10), Guo C., Li J.M., Zhu P., Zhang H.W., Gao W.G. (2017). Design of data transmission system based on FPGA+W5100, Electronic devices, 40 (02), Han J., Ma S. (2016). Design of GPRS data transmission system based on SIM800C, World of electronic products, 23 (11), Hou Y.L. (2016). Design of water regime monitoring system based on GPRS, Automation and instrumentation, (06), Hu J.K., Tang H.C., Fu J., Ran S.S. (2017). Wireless remote meter reading system for gas meter based on GPRS network, Electronic Science and technology, 04 (05), Lu Z., Li J.H. (2017). Design of agricultural irrigation water quality monitoring system based on wireless sensing equipment network, Agricultural Mechanization Research, 39 (07), Ma C.S., Wang X.M., Xu L.P. (2016). The design of separator nrf24l01 wireless data transmission system based on color, Science and Technology Innovation Herald, 13 (02), Qi R.L., Li Y.Y, Jin G.F., Zhang Q.H. (2016). Image transmission and optimization of granary pests based on multi thread parallel technology, Journal of Henan University of Technology (NATURAL SCIENCE EDITION), 37 (03), Tan S.Y., Ma X., Dong W.H., Lu F.Y., Li B.X. (2017). Wireless transmission system of rice seedling tray image based on embedded machine vision, Chinese Journal of agricultural mechanization, 48 (04), Wang W.H. (2017). Design of data acquisition and transmission system based on ZigBee technology, Journal of Wuhan Polytechnic, 16 (01), Xie X.Z., Hu Q., Tang S., Ma B. (2016). A cross layer energy optimized image wireless transmission method, Journal of Chongqing University of Posts and Telecommunications (NATURAL SCIENCE EDITION), 28 (02), Xu C.Y., Qi Z.Y. (2014). Research on cab signal communication system based on wireless MESH network, Railway communication signal, 50 (05), Yang M.Y., He Y., Xu Y.L., Xu Z.G. (2014). Research and development of wireless real time communication system based on closed proprietary network, Computer measurement and control, 22 (01), Zhang F., Liu H.M., Zhang Y.K., Wang J., Qiu Z.M. (2015). Design and implementation of image data transmission system based on WMSNs, Sensor and microsystem, 34 (04), Zhao P. (2017). Software design of remote monitoring and control system based on GPRS, New communication of China, 19 (07),