Fourteen characteristics of "GPRS", an intelligent mobile data communication service

(1) GPRS uses packet switching technology to efficiently transmit high-speed or low-speed data and signaling, optimizing the utilization of network resources and wireless resources.

(2) The new GPRS radio channel is defined and the allocation method is very flexible: Each TDMA frame can be assigned 1-8 radio interface time slots. Timeslots can be shared by active users, and the uplink and downlink allocations are independent.

(3) Support medium and high-rate data transmission, and provide data transmission rate (per user) of 9.05-171.2Kbit/s. GPRS uses a different channel coding scheme than GSM, and defines four coding schemes: CS-1, CS-2, CS-3, and CS-4.

(4) GPRS network access speed is fast, providing a seamless connection with existing data networks.

(5) GPRS supports the application based on standard data communication protocols, and can interconnect with lP network and X.25 network. Supports specific point-to-point and point-to-multipoint services for specific applications such as telematics. GPRS also allows Short Message Service (SMS) to be transmitted over the GPRS wireless channel.

(6) GPRS is designed so that it can support intermittent burst data transmission, and it can support occasional large-scale data transmission. It supports four different Quality of Service (QOS) levels. GPRS can restore the retransmission of data in 0.5-ls. GPRS charging is generally based on the amount of data transmission.

(7) In the GSM Public Land Mobile Network (PLMN), GPRS introduces two new network nodes: one is a GPRS Service Support Node (SGSN), and it is a Mobile Switching (Mobile Switching). The Center, MSC) is at the same hierarchical level and tracks the storage unit of a single mobile station (MS) to implement security functions and access control. The SGSN is connected to the base station system through frame relay; the other is the GPRS gateway support node ( Gateway GPRS Support Node, GGSN). The GGSN supports interworking with external packet switching networks and is connected via an IP-based GPRS backbone network with the SGSN.

(8) The security features of GPRS are the same as the existing GSM security features. Identity authentication and encryption are performed by the SGSN. The algorithm, key and standard of the password setting program are the same as those in the current GSM, but the cryptographic algorithm used by GPRS is optimized for packet data transmission. The GPRS mobile device (ME) can access the GPRS service through a Subscriber Identity Module (SIM) regardless of whether the SIM has GPRS functionality.

(9) Cell selection may be performed automatically by an MS, or the base station system instructs the MS to select a particular cell. The MS informs the network when it reselects another cell or group of cells (ie, a routing area).

(10) In order to access the GPRS service, the MS will first perform a GPRS access procedure to inform the network of its existence. A logical link is established between the MS and the SGSN so that the MS can perform the following operations: receiving GPRS based SMS, paging via SGSN, GPRS data arrival notification.

(11) In order to send and receive GPRS data, the MS activates the packet data address it wants to use. This operation allows the MS to be identified by the corresponding GGSN so that it can start interworking with external data networks.

(12) User data is transmitted transparently between the MS and the external data network. The method used is encapsulation and tunneling: Data packets are packed with specific GPRS protocol information and transmitted between the MS and the GGSN. This transparent transmission method reduces the need for GPRS PLMN interpretation of external data protocols, and it is easy to introduce new interworking protocols in the future. User data can be compressed and protected by retransmission protocols, so data transmission is efficient and reliable.

(13) GPRS can implement charging functions based on data traffic, service types, and QoS levels. The charging method is more reasonable and users can use it more conveniently.

(14) The core network layer of GPRS adopts IP technology. The bottom layer can use a variety of transmission technologies, and it is convenient to realize seamless connection with the rapidly developing IP network.