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  1. 1. On the Road to UMTS Hongyi Wu Xiaojun Cao Copyright, 2000 © SUNY at Buffalo. (Universal Mobile Telecommunications Service)
  2. 2. Outline <ul><li>Introduction to GSM </li></ul><ul><li>GPRS </li></ul><ul><li>EDGE </li></ul><ul><li>UMTS </li></ul><ul><li>WCDMA </li></ul><ul><li>Summery </li></ul>
  3. 3. What is GSM?? (Global System for Mobile Communications)
  4. 4. GSM Architecture <ul><li>Three broad parts </li></ul><ul><ul><li>Mobile Station (MS): carried by the subscriber </li></ul></ul><ul><ul><li>Base Station Subsystem: control radio link with MS </li></ul></ul><ul><ul><li>Network Subsystem: its main part is MSC </li></ul></ul><ul><li>Interfaces: </li></ul><ul><ul><li>Um Interface : known as air interface or radio link. </li></ul></ul><ul><ul><li>Abis Interface: between BTS and BSC </li></ul></ul><ul><ul><li>A Interface: between BSC and MSC </li></ul></ul>
  5. 5. Mobile Station <ul><li>ME( mobile equipment ) </li></ul><ul><ul><li>the terminal </li></ul></ul><ul><li>SIM (Subscriber identity Module) </li></ul><ul><ul><li>provides personal mobility . </li></ul></ul><ul><ul><li>Can insert the SIM card into another GSM terminal and use </li></ul></ul>
  6. 6. Base Station Subsystem <ul><li>BTS (Base Transceiver Station) </li></ul><ul><ul><li>handle the radio link protocols with the Mobile Station </li></ul></ul><ul><ul><li>many BTSs in a large urban area </li></ul></ul><ul><li>BSC (Base Station Controller) </li></ul><ul><ul><li>manages the radio resources for one or more BTSs </li></ul></ul><ul><ul><li>handles such as: channel setup , frequence hopping and handovers . </li></ul></ul><ul><ul><li>connection between MS and MSC </li></ul></ul>
  7. 7. Network Subsystem <ul><li>MSC (Mobile Services Switching Center) </li></ul><ul><ul><li>acts like a normal switching node of the PSTN or ISDN </li></ul></ul><ul><ul><li>provides the connection to the fixed networks (such as the PSTN or ISDN). </li></ul></ul><ul><li>HLR (Home Location Register ) </li></ul><ul><ul><li>contains information of each subscriber registered in the corresponding GSM network, along with the current location of the mobile. </li></ul></ul><ul><ul><li>logically one HLR per GSM network </li></ul></ul>
  8. 8. Network Subsystem cont. <ul><li>VLR (Visitor Location Register) </li></ul><ul><ul><li>contains selected information from the HLR, necessary for call control and provision of the subscribed services, </li></ul></ul><ul><ul><li>each mobile currently located in the geographical area controlled by the VLR. </li></ul></ul><ul><li>EIR (The Equipment Identity Register) </li></ul><ul><ul><li>a database that contains a list of all valid mobile equipment on the network, </li></ul></ul><ul><li>AuC (The Authentication Center) </li></ul><ul><ul><li>is a protected database:secret key of SIM </li></ul></ul>
  9. 9. GSM Features <ul><li>Multiple access: use TDMA/FDMA to share the limited radio spectrum </li></ul><ul><ul><li>The FDMA part involves the division by frequency of the (maximum) 25 MHz bandwidth into 124 carrier frequencies spaced 200 kHz apart. </li></ul></ul><ul><ul><li>Each of these carrier frequencies is then divided in time, using a TDMA scheme. </li></ul></ul><ul><li>GSM is a digital network </li></ul><ul><ul><li>Based on Circuit-switch </li></ul></ul>
  10. 10. GSM Features cont. <ul><li>SMS: Short Message Service </li></ul><ul><ul><li>is a bi-directional service for short (up to 160 bytes) messages. Messages are transported in a store-and-forward fashion. </li></ul></ul><ul><ul><li>an acknowledgement of receipt is provided to the sender. </li></ul></ul><ul><ul><li>can also be used in a cell-broadcast mode, for sending messages such as traffic updates or news updates. Messages can also be stored in the SIM card for later retrieval </li></ul></ul>
  11. 11. GPRS System (General Packet Radio Service)
  12. 12. GPRS Architecture <ul><li>Introduce two new nodes into GSM network </li></ul><ul><ul><li>SGSN (the Serving GPRS Support Node): </li></ul></ul><ul><ul><ul><li>Keep track of the location of the mobile within its service area and send/receive packets from the mobile , passing them on, or receiving them from the GGSN </li></ul></ul></ul><ul><ul><li>GGSN (Gateway GPRS Support Node): </li></ul></ul><ul><ul><ul><li>convert the GSM packets into other packet protocols (e.g.IP or X.25) and send them out into another network. </li></ul></ul></ul>
  13. 13. GPRS Features <ul><li>Log on to GPRS </li></ul><ul><ul><li>A GPRS-capable terminal communicates with GSM base Stations, but unlike circuit-switched data calls which connects to MSC, GPRS packets are sent sent from the base station to SGSN, SGSN communicates with GGSN. </li></ul></ul><ul><ul><li>Establishes a Packet Data Protocol (PDP) which is logical connection between the mobile and GGSN </li></ul></ul><ul><ul><li>now visible to the outside fixed networks </li></ul></ul>
  14. 14. GPRS Features Cont. <ul><ul><li>SGSN and GGSN use GPRS tunnel protocol (GTP) which operates over the top of TCP/IP to encapsulate the packets </li></ul></ul><ul><ul><li>Tunnels: information may be encrypted and additional data is added to each packet to prevent tampering </li></ul></ul><ul><li>Packed based </li></ul><ul><ul><li>No dial-up, just as with a LAN connection. </li></ul></ul><ul><ul><li>No delay for sending data </li></ul></ul>
  15. 15. GPRS Features Cont. <ul><ul><li>pay for the amount of data they actually communicate, and not the idle time </li></ul></ul><ul><ul><li>users need to confirm their agreement to pay for the delivery of content from the service. This is performed by using WAP (Wireless Application Protocol) </li></ul></ul><ul><ul><li>unsolicited packets may not be charged </li></ul></ul><ul><ul><li>voice and Data Communication at the same time </li></ul></ul><ul><ul><li>can be viewed as a sub-network of the Internet </li></ul></ul>
  16. 16. GPRS Features Cont. <ul><li>Spectrum Efficiency </li></ul><ul><ul><li>users can share the resource (Radio link),it is used only when users are actually sending or receiving data </li></ul></ul><ul><li>Speed: Based on GMSK </li></ul><ul><ul><li>a modulation technique known as Gaussian minimum-shift keying. </li></ul></ul><ul><ul><li>Theoretical Max speeds up to 171.2kbps.(GSM:9.6Kbps) </li></ul></ul>
  17. 17. GPRS Features Cont. <ul><ul><li>a channel that is 200kHz wide, is divided into 8 separate data streams, each carrying maximum 20kbps(14.4kbps typical), GSM only use one channel, GPRS combine up to 8 of these channels. </li></ul></ul><ul><li>complement rather than replace the current data services available through today’s GSM </li></ul><ul><ul><li>doesn't require new radio spectrum </li></ul></ul><ul><ul><li>supports TDMA: also use for IS-136 </li></ul></ul>
  18. 18. GPRS Phrase <ul><li>Phrase 1 </li></ul><ul><ul><li>expectedly to be available commercially in 2001, Point to point GPRS will be supported </li></ul></ul><ul><li>Phrase 2 </li></ul><ul><ul><li>net yet fully defined, but is expected to higher data rates through possible incorporation of techniques such as EDGE, in addition to Point-to-Multipoint support. </li></ul></ul>
  19. 19. EDGE (Enhanced Data Rates for GSM Evolution)
  20. 20. <ul><li>Introduce new methods at the physical layer </li></ul><ul><ul><li>new form of modulation: 8PSK(phrase Shift Keying) </li></ul></ul><ul><ul><ul><li>introduced as a complement to GMSK (Gaussian Filter Minimum Shift Keying) </li></ul></ul></ul><ul><ul><ul><li>8PSK: use 8 phrases to carry signals </li></ul></ul></ul><ul><ul><li>Different ways of encoding </li></ul></ul><ul><ul><ul><li>nine MCS(Module Coding Schemes) have been defined, from 8.8kbps per timeslot(MCS-1 with GMSK modulation) up to 59.2kbps per timeslot(MCS-9 with 8PSK modulation) </li></ul></ul></ul><ul><ul><li>High radio interface data rates (up to 384kbps) </li></ul></ul>EDGE Features
  21. 21. EDGE Features cont. <ul><li>Provides an evolutionary migration path from GPRS to UMTS </li></ul><ul><ul><li>Only one EDGE transceiver unit need to be added to each cell. </li></ul></ul><ul><ul><li>Software upgrades to BSC and Base Stations can be carried out remotely. </li></ul></ul><ul><ul><li>Higher layer protocols (GGSN, SGSN) stay the same </li></ul></ul><ul><ul><li>Can be introduced smoothly in GPRS(doesn’t require any new elements) </li></ul></ul>
  22. 22. EDGE Features cont. <ul><li>EDGE is a technology both for </li></ul><ul><ul><li>HSCSD ( High Speed Circuit Switched Data ) is simply a Circuit Switched Data call in which a single user can take over up to four separate channels at the same time. </li></ul></ul><ul><ul><li>and for GPRS ( General Packet Radio Service ) to meet the demands of wireless multimedia applications. </li></ul></ul><ul><ul><li>Also introduced into existing IS-136 networks </li></ul></ul>
  23. 23. EDGE Features cont. <ul><li>The Data networking for WCDMA will likely be based on EDGE/GPRS infrastructure protocols, Such as GTP( GPRS Tunneling Protocol ) </li></ul><ul><li>As a consequence EDGE is a way to provide 3G services on 2G networks </li></ul>
  24. 24. Scenario for Migration from 2G to 3G
  25. 25. What are 3G Technologies? <ul><li>UMTS (Universal Mobile Telecommunications Service) </li></ul><ul><ul><li>EDGE can co-exist with UMTS </li></ul></ul><ul><ul><ul><li>e.g. Edge provide high speed services for wide-area coverage while UMTS is deployed in urban hot spots. </li></ul></ul></ul><ul><li>Cdma 2000 </li></ul><ul><ul><li>based on the cdma One standard, two air modes: </li></ul></ul><ul><ul><ul><li>one based on the parallel use of 3 contiguous cdmaOne carriers (multi-carrier approach), </li></ul></ul></ul><ul><ul><ul><li>the other one on the use of the corresponding 3 carriers width spreading (direct spread approach) </li></ul></ul></ul>
  26. 26. What are 3G Technologies? Cont. <ul><li>UWC-136 (USA cellular standard) </li></ul><ul><ul><li>based on GPRS and EDGE technologies defined by ETSI for data on overlay of ANSI-136 &quot;classical&quot; networks for voice. Nevertheless, UWC-136 can benefit from the expected standardization of voice over IP (VoIP) on EDGE. D-AMPS operators mainly promote UWC-136. </li></ul></ul>
  27. 27. To be Continued <ul><li>Mr. HongYi Wu will give us More detail about these topics </li></ul>
  28. 28. What does UMTS provide? <ul><li>Circuit- and Packet-Oriented Services </li></ul><ul><li>Seamless Global Roaming </li></ul><ul><li>Capacity and Capability to serve more than 50% population </li></ul><ul><li>A Wide Range of Services </li></ul><ul><ul><li>Voice, low-rate data and high-rate data </li></ul></ul><ul><ul><li>144kb/s, 384kb/s , 2Mb/s </li></ul></ul>
  29. 29. UMTS coverage vs. bit rate Outdoors Vehicle Walk Fixed Indoors 155Mb/s 2.0 0.5 GSM UMTS Broadband Radio
  30. 30. UMTS Hierarchical Cell Structure Satellite Mega-Cell Satellite Mega-Cell Macro-Cell Macro-Cell Micro-Cell Pico-Cell Micro-Cell Pico-Cell Micro-Cell Pico-Cell Micro-Cell Pico-Cell
  31. 31. UTRAN- UMTS Terrestrial Radio Access Network Core Network RNC Node B Node B RNC Node B Node B RNC Node B Node B MH lu lu lu lur lur Uu lub
  32. 32. Frequency Allocation <ul><li>1920-1980 MHz paired with 2110-2170 MHz </li></ul><ul><li>Total 35 MHz unpaired band </li></ul>1920 1980 2010 2025 C C A MSS B A’ 2110 2170 2200 MSS
  33. 33. FDD vs. TDD <ul><li>Both FDD and TDD are available in UMTS </li></ul><ul><li>TDD has been designed for use in high density areas </li></ul><ul><li>The highest bearer rate: </li></ul><ul><ul><li>TDD-2.048Mb/s </li></ul></ul><ul><ul><li>FDD-384kb/s </li></ul></ul>
  34. 34. WCDMA <ul><li>Radio Parameters </li></ul><ul><li>Performance Improvement </li></ul><ul><li>Channels </li></ul><ul><li>Channel Generation </li></ul><ul><li>Power Control </li></ul><ul><li>Handoff </li></ul>
  35. 35. WCDMA Radio Parameters <ul><li>Group 200KHz bands into 4.2-5.0 MHz carriers </li></ul><ul><li>Chip Rate is 4.096 Mchips/sec </li></ul><ul><li>System Capacity of 128 channels per cell provided by 5 MHz bandwidth </li></ul>
  36. 36. WCDMA Performance Improvement <ul><li>Capacity Improvement </li></ul><ul><li>No Frequency Planning </li></ul><ul><li>Multiple Services per Connection </li></ul><ul><li>Frequency Handoff </li></ul><ul><ul><li>HCS </li></ul></ul><ul><ul><li>Hot Spot </li></ul></ul>
  37. 37. HCS & Hot-Spot HCS-Scenario f1 f1 f2 Macro Macro Micro Handoff between layers is alwayse needed f1 f1 f1 f2 Hot-Spot Scenario Hot-Spot Handoff at Hot-Spot is sometimes needed
  38. 38. WCDMA Channels <ul><li>Forward WCDMA Channels </li></ul><ul><ul><li>Pilot Channel </li></ul></ul><ul><ul><li>Sync Channel </li></ul></ul><ul><ul><li>Paging Channel </li></ul></ul><ul><ul><li>Forward Traffic Channel </li></ul></ul><ul><ul><ul><li>Forward Information Channel </li></ul></ul></ul><ul><ul><ul><li>Forward Singal Channel </li></ul></ul></ul>
  39. 39. WCDMA Channels <ul><li>Reverse WCDMA Channels </li></ul><ul><ul><li>Access Channel </li></ul></ul><ul><ul><li>Reverse Traffic Channel </li></ul></ul><ul><ul><ul><li>Reverse Information Channel </li></ul></ul></ul><ul><ul><ul><li>Reverse Signaling Channel </li></ul></ul></ul>
  40. 40. An Example of Channel Generation 16 kbps Convolutional Encoder R=1/2, k=9 Block Interleaver Symbol Repetition 16 ksps 64 ksps Long Code Generator 4.096 Mcps A Forward WCDMA Sync Channel Walsh 128 16 ksps 16 ksps 16 ksps 64 ksps
  41. 41. WCDMA Convolutional Encoder Output Symbols (a1,a2) (b1,b2) … ... Input data a,b,... A (2,1,8) Convolutional Encoder Implemented by LFSR
  42. 42. WCDMA Block Interleaving 1 9 17 25 2 10 18 26 3 11 19 27 4 12 20 28 5 13 21 29 6 14 22 30 7 15 23 31 8 16 24 32 1 ... 17 ... 9 ... 25 ... 5 ... 21 ... 13 ... 29 ...
  43. 43. WCDMA Orthoganal Modulation <ul><li>Walsh Code Generation </li></ul>
  44. 44. CDMA Orthoganal Modulation <ul><li>Modulation </li></ul><ul><ul><li>Take 6 bit from the input stream (C 0 , C 1 , C 2 , C 3 , C 4 , C 5 ) </li></ul></ul><ul><ul><li>Compute MSI (Modulation Symbol Index) </li></ul></ul><ul><ul><li>MSI= C 0 +2 C 1 +4 C 2 +8C 3 +16C 4 +32 C 5 </li></ul></ul><ul><ul><li>Each of the six symbol group is mapped to the row(MSI) of H 128 </li></ul></ul>
  45. 45. WCDMA Direct Sequence Spreading Long Code Seed XOR Long Code 4.096 Mcps <ul><li>Long Code Generation by LFSR </li></ul>1 x x 2 x 32
  46. 46. WCDMA Direct Sequence Spreading 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 1 0 1 0 1 1 1 0 0 1 1 1 1 0 0 1 1 0 1 1 0 0 0 0 0 1 1 1 1 0 0 1 t t t d w (t) C(t) D s (t)
  47. 47. Power Control In WCDMA N: Spread Factor  p : Carrier-to-Interference-Ratio for subscriber P <ul><li>Bit Error Rate and Power </li></ul>
  48. 48. <ul><li>Perfect Power Control </li></ul>Power Control In WCDMA
  49. 49. Power Control In WCDMA <ul><li>Near-Far Problem in CDMA </li></ul><ul><ul><li>Different Performance for Subcriber Links </li></ul></ul><ul><ul><li>A Few Subscribers closest to the BTS may contribute too much multiple Access Interference. </li></ul></ul>
  50. 50. Power Control In WCDMA <ul><li>How to do power control </li></ul><ul><ul><li>Force all users to transmit the minimum amount of power </li></ul></ul><ul><ul><li>Reduce the power transmitted by users closest to the BTS; increase the power transmitted by users farest to the BTS </li></ul></ul>
  51. 51. Power Control In WCDMA <ul><li>Open Loop vs. Close Loop </li></ul><ul><ul><li>Open Loop Power Control </li></ul></ul><ul><ul><li>Subscriber measures the DL power and adjusts its transmission power </li></ul></ul><ul><ul><li>Close Loop Power Control </li></ul></ul><ul><ul><li>BS measures the UL power. MS measures the DL power and reports to the BS. BS instructs the user to raise or lower it transmission power </li></ul></ul>
  52. 52. WCDMA Soft Handoff Active set = BS1 BS1 BS2 Active set = BS1 & BS2 BS2 SS > add threshold BS1 BS2 Active set = BS2 BS1 SS < drop threshold BS1 BS2
  53. 53. Active Research Topics <ul><li>Cellular system architecture </li></ul><ul><li>UMTS air interface </li></ul><ul><li>Power control in CDMA </li></ul><ul><li>Handoff </li></ul><ul><li>Satellite-UMTS traffic </li></ul>
  54. 54. Reference <ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul>
  55. 55. Reference <ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li>S. Dutnall, N. Lobley, A. Clapton, UMTS: The mobile part of broadband communications for the next century IEEE Atm Workshop, Proceedings. p242-252,1998 </li></ul><ul><li>S. Breyer, G. Dega, V. Kumar, L. Szabo, Global view of the UMTS concept Alcatel Telecommunications Review. n 3 1999. p 219-227 </li></ul><ul><li>M. Lee, CDMA Network Security , Prentice-Hall, 1998 </li></ul><ul><li>U. Black, Mobile & Wireless Networks , Prentice-Hall, 1999 </li></ul><ul><li>M. Gallagher, W. Webb, UMTS: The next generation of mobile radio, IEE Review. v 45 n 2 1999. p 59-63 </li></ul>
  56. 56. Reference <ul><li>A. Samukic, UMTS Universal Mobile Telecommunications System:Development of standards for the third generation, IEEE Global Telecommunications Conference & Exhibition. v 4 1998. p 1976-1983 </li></ul><ul><li>N. Prasad, GSM evolution towards third generation UMTS/IMT2000, IEEE International Conference on Personal Wireless Communications 1999, p 50-54 </li></ul><ul><li>A. Samukic, UMTS universal mobile telecommunications system: Development of standards for the third generation, IEEE Transactions on Vehicular Technology. v 47 n 4 Nov 1998. p 1099-1104 </li></ul>