PROJECT: GPRS WIRELESS SYSTEMS (TSKS03) Name : Susmita Saha Pnr : 910619-T282 Email : [email protected] Assignment 2016 Wireless Systems (ISY) Linköping University (Li.U), SE-581 83 Linköping, Sweden 1 Table of Contents Acronyms ................................................................................................................................................ 3 1. Introduction .................................................................................................................................... 4 2. History of GPRS ............................................................................................................................... 4 3. GPRS Characteristics ....................................................................................................................... 4 4. GSM Architecture ............................................................................................................................ 4 5. GPRS Description ............................................................................................................................ 6 6. GPRS Architecture ........................................................................................................................... 6 7. GPRS modulation ............................................................................................................................ 8 8. GPRS performance categories ........................................................................................................ 8 9. Error correction and coding scheme ............................................................................................... 9 10. Services offered by GPRS .......................................................................................................... 10 11. Advantages ................................................................................................................................ 11 12. Drawbacks ................................................................................................................................. 11 13. Conclusion ................................................................................................................................. 11 14. References ................................................................................................................................ 12 2 Acronyms GPRS- General Packet Radio Service. GSM- Global systems for mobile communications. SGSN- Serving GPRS Support Node. GGSN- Gateway GPRS support node. MS- Mobile station. PDP- Packet data protocol. BSS- Base Station subsystem. NSS- Network station subsystem. RSS- Radio station subsystem. GSS- Gateway subsystem. BTS- Base transceiver station. BSC- Base station controller. MSC- Mobile switching centre. HLR- Home location register. VLR- Visitor location register. EIR- Equipment identity register. AUC- Authentication centre. PCU- Packet control unit. BG- Border gateway. CG- Charging gateway. DNS- Domain name server. PSTN- Public switch telephone network. PLMN- Public land mobile network. CKSN- Cipher key sequence number. PDN- Packet data network. IN- Intelligent Network. GMSC- Gateway mobile switching centre. SMSC- Short message service centre. ETSI- European Telecommunications standards institute. SIM- Subscriber identity module. NMS- Network management system. OSS- Operation station subsystem. OMC- Operation and maintenance centre. OMCR- Operation and maintenance centre for radio. OMCS- Operation and maintenance centre for switch. ETSI- European Telecommunications Standards Institute. 3GPP- 3rd Generation Partnership Project. TDMA- Time division multiple access. CDMA- Code division multiple access. 3 1. Introduction The report is about the General Packet Radio Service (GPRS) which is a packet oriented technology for GSM (Global systems for mobile communications) mobile communication network. GPRS is mentioned as 2.5G because it offers the services which are the middle of 2G (second generation) and 3G (third generation). For providing the end-to-end packet switched services the GPRS reuses the existing GSM infrastructure. GPRS makes sending and receiving small bus of data possible through a mobile phone. GPRS technology allows for higher data rates compared to the GSM cellular network. This technology allows the user to check their mail and download the large volume of data on a mobile phone. GPRS standards were established by the ETSI (European Telecommunications Standards Institute), but now it is controlled by the 3GPP (3rd Generation Partnership Project). 2. History of GPRS In 1994, ETSI was initiated for GPRS standardization. In 1997, GPRS specifications were certified by ETSI and was completed in 1999. In 1999, cellular network started GPRS technology into their configuration but it became available in 2001. 3. GPRS Characteristics The characteristics of GPRS are given below [5]: GPRS uses packet-switched network. GPRS uses GSM architecture and GPRS support nodes. GPRS enables voice and data flow through the network. GPRS has dynamic time slot allocation. GPRS is faster than GSM and Code division multiple access (CDMA). 4. GSM Architecture The full form of GSM is Global systems for mobile communications, which is the voice technology under second generation (2G). For GSM architecture first entity is required as MS (mobile station). The next part as per the GSM architecture requires is BSS (Base Station subsystem); the BSS part is required to be attached with NSS (Network station subsystem). Both the BSS and NSS part are managed by the entity called NMS (Network management system), which is also known as OSS (operation station subsystem) or OMC (Operation and maintenance centre). So, GSM architecture requires four basic entities. The first entity MS is connected with BSS. The BSS consists of BTS (Base transceiver station) and BSC (Base station controller). BTS is controlled by BSC. GSM architecture requires NSS as well. The 4 main unit of NSS part is MSC (Mobile switching centre), which works as a controller of BSC. MSC has a part which is known as SMSC (Short message service centre) and databases are HLR (Home location register), VLR (Visitor location register), EIR (Equipment identity register), AUC (Authentication centre), IN (Intelligent network), other connectivity is PSTN (Public switch telephone network) and MSC is connected with GMSC (Gateway mobile switching centre) also. OMC is divided into two parts, which are OMCR (Operation and maintenance centre for radio) and OMCS (Operation and maintenance centre for switch). OMCR manages the radio part known as BSS part and NSS part is managed by OMCS. OMC is worked as network management and operation station subsystem. Figure 1: GSM architecture [8] The MS is required to attach the BSS part with the air interface (Um). It means antennas receive signals and forward those signals to the BTS. The full form of BTS is Base transceiver station; that means a unit that can transmit as well as receive. BTS manages or controls all the calls from the MS to BTS and BTS forwards these calls to BSC. The mobile station signals are received by BTS. All BTS in a particular area is managed by BSC. All the signals of BSC forwards to MSC. Switching part is managed by MSC unit. All the switching functionalities, the authentication, verification as well as security purpose are managed by mobile switching part. HLR has a functionality that stores the permanent location of the users. Handover or changing location are saved in VLR. EIR has divided in three lists users: white list users, grey list users and black list users. White list users are the normal users- those who are communicating. Grey list users are the service denied users. Black list is the total number of users, who are blocked by the networks. So, EIR checks the list whether the users are available in white list, grey list or black list. In SIM (Subscriber identity module) there exists a key store and same key store is also in the AUC database. If the SIM wants to communicate with the network, AUC matches the key. If key matches then only the user can call. IN is worked as billing section for the prepaid connection. Post-paid bills are generated by MSC. GMSC is required to connect number of MSCs (Mobile switching centres) together. GMSC is used for international calls. SMSC (Short message service centre) basically deals with short messages. Every messages is stored first in SMSC databases and then 5 it is forwarded to the receiver. If users require to call then it passes through the MSC and if users require to message then it needs to pass through the SMSC. PSTN (Public switch telephone network) stands for landline connectivity. It connects MS to landline. 5. GPRS Description GPRS packet technology means transmission of packets through air and this packet contains two kinds of data. They are: Data Information and Control information. Control information provides source and destination address to pass the data. Control information chooses the route from source to destination address and data information contains the data which must be decrypted at the destination address. Control information also contains error correction bits to control the errors. A GPRS packet can be divided into three parts- the first part in header, last part is trailer, the middle part is payload. Header represents the start of the packet, trailer represents the end of the packet, in between there is a payload with data which can