Introduction COMSM0106 Mobile and GRPS improves GSM in a number - PDF document

Introduction COMSM0106 – Mobile and • GRPS improves GSM in a number of ways: – increases data transmission speeds (<171.2Kbit/s) Ubiquitous Computing – Increases interoperability with packet-switched data networks e.g. internet – Allows billing by data transaction volume rather than billing by connection time • However, GPRS itself still has some ‘issues’ Mobile Telephony Protocols 3 - – Still quite slow, especially for multimedia and other high bandwidth transmission situations UMTS – Speech quality – Inconsistent user interface across different networks • Note: we will not be covering 3G in as much detail as, e.g. GSM. Dr. Mike Fraser This is because it is remarkably lacking in innovation and uses many of the same conceptual treatments as the original GSM fraser@cs.bris.ac.uk specifications describe COMSM0106 – Mobile and COMSM0106 – Mobile and Ubiquitous Computing Ubiquitous Computing 3G - The Future™ UMTS Services (1) • Universal Mobile Telecommunications System • Teleservices (UMTS) is the generally accepted protocol for – Speech 3G networks – SMS • Bearer services • Defined by the Third Generation Partnership Project (3GPP) – data transfer between points of access • Bearer services can be altered at session or connection • First commercial 3G network: Japan, establishment and during ongoing session or connection 2001(CDMA2000) • Point-to-Point and Point-to-Multipoint • First commercial UMTS network: Norway, 2001 • data rate targets are: • Currently around 130M 3G users worldwide – 144 kbits/s satellite and rural outdoor • EU says operators must cover 80% of the – 384 kbits/s urban outdoor national population by 2005 – 2048 kbits/s indoor and low range outdoor COMSM0106 – Mobile and COMSM0106 – Mobile and Ubiquitous Computing Ubiquitous Computing UMTS Services (2) UMTS Architecture (1) • Bearer services have different QoS parameters for • Three domains: maximum transfer delay, delay variation and bit error – Core Network (CN) rate. Four types: – UMTS Terrestrial Radio Access Network (UTRAN) – User Equipment (UE) – Conversational class (voice, video telephony, video gaming) • The core network provides switching, routing and transit for traffic – Streaming class (multimedia, video on demand, webcast) • Core network also contains the databases and network – Interactive class (web browsing, network gaming, database access) management functions – Background class (email, SMS, downloading) • Virtual Home Environment (VHE) • Compare to GSM: – Network Subsystem – Users are consistently presented with the same personalised – Base Station Subsystem features – Mobile Station – User Interface customisation and services in whatever network • UTRAN provides the air interface for accessing User Equipment or terminal, wherever the user is from the network • Improved network security • Base Station: Node-B • Location-based services • Control equipment: Radio Network Controller (RNC) COMSM0106 – Mobile and COMSM0106 – Mobile and Ubiquitous Computing Ubiquitous Computing 1

UMTS Architecture (2) UMTS Architecture (3) • Circuit switched and packet switched domains • What’s new here compared • Circuit switched: to GSM? On the surface, not – Mobile services Switching Centre (MSC) much, e.g.: – Visitor location register (VLR) – Gateway MSC • RNC (c.f. GSM BSC) • Packet switched: – Serving and Gateway GPRS Support Nodes (SGSN, GGSN • Shared: • Node B (c.f. GSM BTS) – EIR, HLR, VLR, AUC • MSC, VLR and SGSN merge to become a UMTS MSC • In practice, UMTS will • The architecture of Core Network may change when new services are require separate hardware introduced – Number Portability Database (NPDB) enables user to change the network while due to speed, frequency and keeping old phone number operational issues – Gateway Location Register (GLR) used to optimise subscriber handling between network boundaries COMSM0106 – Mobile and COMSM0106 – Mobile and Ubiquitous Computing Ubiquitous Computing ATM Transmission WCDMA (1) • The Asynchronous Transfer Mode (ATM) • Code-Division Multiple- Access (CDMA) : is defined for UMTS core transmission – every communicator will • ATM Adaptation Layer type 2 (AAL2) be allocated the entire handles circuit switched connection (for spectrum all of the time voice) • Opposed to (some) GSM systems which • ATM Adaptation Layer type 5 (AAL5) use TDMA (time), handles packet switched connection (for FDMA (frequency) or data) both COMSM0106 – Mobile and COMSM0106 – Mobile and Ubiquitous Computing Ubiquitous Computing WCDMA (2) Node-B and RNC • Node-B (as per BTS): • Wideband Code-Division Multiple- – Air interface Transmission / Reception Access (WCDMA) is Direct – Modulation / Demodulation Sequence CDMA system – Error Handing – user data is multiplied with quasi- – Power Control random bits derived from WCDMA • RNC (as per BSC): spreading codes – Radio Resource Control • WCDMA has two basic modes of – Admission Control operation – Channel Allocation – Frequency Division Duplex (FDD) – Power Control Settings – Time Division Duplex (TDD) – Handover Control • Different users can simultaneously – Ciphering transmit at different data rates and – Segmentation / Reassembly data rates can even vary in time – Broadcast Signalling • This is where the speed comes in – Open Loop Power Control COMSM0106 – Mobile and COMSM0106 – Mobile and Ubiquitous Computing Ubiquitous Computing 2

User Equipment (1) User Equipment (2) • UMTS mobile station can operate in one of three modes involving packet-switching • The UMTS standard does not restrict User (PS) and circuit switching (CS): PS/CS mode : – Equipment functionality • Station is attached to both the PS domain and CS domain, and is capable of simultaneously operating PS and CS services PS mode : – • Terminals work as air interface counter • Station is attached to the PS domain only • This does not prevent CS-like services to be offered over the PS domain (like Voice over IP) part for Node-B/RAN CS mode : – • Station is attached to the CS domain only and may only operate services of the CS UMTS IC card has same physical characteristics as GSM SIM card. It has several functions: • Most UMTS identity types taken directly • Support of one User Service Identity Module (USIM) application (optionally more that one) from GSM specifications, e.g.: • Support of one or more user profile on the USIM • Update USIM specific information over the air – International Mobile Subscriber Identity (IMSI) • Security functions • User authentication – International Mobile Station Equipment • Secure downloading of new applications Identity (IMEI) COMSM0106 – Mobile and COMSM0106 – Mobile and Ubiquitous Computing Ubiquitous Computing Conclusions • Have now looked at most common protocols for local area-high bandwidth and wide area-low (but improving) bandwidth • Next: last lecture on wireless networking! – Alternative methods for wireless networking – Alternative we missed by looking at WiFi and phones • After that: Sensors and sensorship COMSM0106 – Mobile and Ubiquitous Computing 3