UMTS 3rd generation networks solution Tomasz Kaczmarczyk, DOTR Ericpol Telecom Sp. z o.o. Tomasz.Kaczmarczyk@ericpol.pl Tel.: +48 663 426 806 GSM Overview 1 2
Agenda UMTS basis Radio Interface Power control mechanisms UMTS handover types UMTS security mechanisms Agenda 3 3 UMTS basis 4 4
Cellular networks evolution GSM GPRS UMTS NMT CSD EDGE HSPA HSCSD UWC-136 HSPA+ JTACS TACS AMPS EV-DO D-AMPS cdmaone CDMA2000 IS-136 (TDMA) IS-95A IS-2000 IS-95B - 1G - 2G - 2,5G - 2,75G - 3,9G - 3G - 3,5G - network migration - network evolution LTE 5 5 3G (UMTS) general assumptions common initial spectrum worldwide (1.8-2.2 GHz band) wide range of services (voice, data, multimedia, internet) data rates up to 2 Mb/s (CS, PS modes) global seamless roaming and service delivery enhanced security and performance integration of multiple radio (cellular, cordless, wireless) and satellite systems QoS mechanisms 6 6
Time Division Duplex UTRA Unpaired Band: TD-CDMA 1900-1920 MHz and 2010-2025 MHz Mobile Satellite Service: 2x 30 MHz Uplink: 1980-2010 MHz Downlink: 2170-2200 MHz 1900 1950 2000 2050 2100 2150 2200 TDD FDD MSS FDD MSS TDD f MHz UTRA Paired Band: WCDMA Uplink: 1920-1980 MHz Downlink: 2110-2170 MHz Frequency Division Duplex: 2x 60 MHz UMTS spectrum for Europe 7 7 WCDMA channels allocation (Poland) 8 Operator FDD channels TDD channels Era (PTC) Plus (Polkomtel) Orange (PTK Centertel) Play (P4) 1935.3-1950.1 MHz (Uplink) 2125.3-2140.1 MHz (Downlink) 1950.1-1964.9 MHz (Uplink) 2140.1-2154.9 MHz (Downlink) 1920.5-1935.3 MHz (Uplink) 2110.5-2125.3 MHz (Downlink) 1964.9-1979.7 MHz (Uplink) 2154.9-2169.7 MHz (Downlink) 1910.1-1915.1 MHz 1905.1-1910.1 MHz 1915.1-1920.1 MHz 1900.1-1905.1 MHz 1900,1 MHz 1920,5 MHz C B A D D D D A A A B B B C C C 1920,1 MHz 1979,7 MHz 8
GSM/UMTS network R99 9 PSTN PSTN SS BSS (GERAN) PLMN PLMN GMSC VLR MSC BSC/TRC BTS BTS ISDN ISDN HLR AUC EIR UTRAN INTERNET INTERNET GGSN SGSN 9 GSM/UMTS network R4 PSTN PSTN SS MGW MGW BSS (GERAN) PLMN PLMN ISDN ISDN MSS MSS BSC/TRC BTS BTS HLR AUC EIR UTRAN INTERNET INTERNET GGSN SGSN 10 10
GSM/UMTS network R5 PSTN PSTN SS MGW MGW BSS (GERAN) PLMN PLMN ISDN ISDN MSS MSS BSC/TRC BTS BTS HSS (HLR & AuC) EIR IMS UTRAN INTERNET INTERNET GGSN SGSN 11 11 GSM/UMTS network R6 PSTN PSTN SS MGW MGW BSS (GERAN) PLMN PLMN ISDN ISDN MSS MSS BSC/TRC BTS BTS IMS HSS (HLR & AuC) EIR AAA UTRAN WLAN INTERNET INTERNET GGSN SGSN 12 12
GSM/UMTS network R8 13 PSTN PSTN SS MGW MGW BSS (GERAN) PLMN PLMN ISDN ISDN MSS MSS BSC/TRC BTS BTS HSS (HLR & AuC) EIR IMS AAA UTRAN INTERNET INTERNET GGSN SGSN enb enb WLAN w ramach Europejskiego S-GW Funduszu Społecznego PDN-GW E-UTRAN 13 UTRAN architecture UTRAN Iub Iu-CS MSC Iu-CS Iur RNS Iu-PS Uu Iu-PS SGSN Iub UE RNS 14 14
Radio Interface 15 15 TACS AMPS NMT 1G systems: time Channel 1 No synchronization in time needed Channel 2 Channel 3 Channel 4 Continuous transmission and reception Channel 5 One (frequency) physical channel per subscriber frequency FDMA Frequency Division Multiple Access 16 16
D-AMPS (TDMA + FDMA) GSM (TDMA + FDMA) 2G systems: time Synchronization in time needed One freq. channel TS 1 TS 2 TS 3 TS 4 TS 5 Discontinuous transmission and reception One (Time Slot) physical channel per subscriber frequency TDMA Time Division Multiple Access 17 17 WCDMA 5 MHz CDMA2000 3,75 MHz IS-95 1,25 MHz 3G systems: time FDD or TDD for UMTS One coded Continuous reception and transmission channel Channel Channel 8 9 Channel Channel 6 7 Channel Channel 4 5 Channel Channel 2 3 User 1 Large bandwidth Users separation through different codes frequency (W)CDMA (Wideband) Code Division Multiple Access 18 18
Spreading concept time domain The user information bits are spread into a number of chips Chip rate = 3,84 Mchip/s Bandwidth = 5 MHz d(t) 1 1 1 0 Original user data 960 kbit/s XOR c(t) Chip-by-chip multiplication C4,2 SF=4 e(t) = Spread signal 19 19 WCDMA features WCDMA advantages: Wideband transmission less sensitive to selective frequency interference and fading Power density decreased good jamming resistance information transfer below (wideband) background noise Easier radio network planning frequency reuse = 1 Soft/Softer handover less power used in one cell WCDMA disadvantages: Fast power control mechanism necessary Soft handover a few cells resources reserved for one call 20 20
UTRAN radio signal processing step 1) Channelization transformation of each data symbol into multiple chips OVSF Orthogonal Variable Spreading Factor step 2) Scrambling information individualization and signals transmission features improvement Gold codes Short codes Data (physical channel) Spreading code Scrambling code Filtration, Modulation, Signal shaping Data (physical channel) Spreading code Scrambling code Receiving, Demodulation, Amplifying 21 21 Channelization codes 22 Increase bandwidth 3,84 Mcp/s Spreading Factor (code length): 4-256 chips uplink 4-512 chips - downlink Managed by Allow to: UPLINK - Separate physical channels (different services) from the same terminal (up to 3 channelization codes used by UE) DOWNLINK - Separate connection to different terminals from one (one channelization code per UE) Physical channels can be spread with different SF-factor codes the higher SF the lower physical channel amplification E C E b I I lg 0 [ db ] = [ db ] + 10 ( SF ) 0 22
OVSF codes tree C4,0 (1,1,1,1) C2,0 (1,1) C4,1 (1,1,-1,-1) C1,0 (1) C4,2 (1,-1,1,-1) C2,1 (1,-1) C4,3 (1,-1,-1,1) 23 C8,0 (1,1,1,1,1,1,1,1) C16,0 (1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1) C16,1 (1,1,1,1,1,1,1,1,-1,-1,-1,-1,-1,-1,-1,-1) C16,2 (1,1,1,1,-1,-1,-1,-1,1,1,1,1,-1,-1,-1,-1) C8,1 (1,1,1,1,-1,-1,-1,-1) C16,3 (1,1,1,1,-1,-1,-1,-1,-1,-1,-1,-1,1,1,1,1) C16,4 (1,1,-1,-1,1,1,-1,-1,1,1,-1,-1,1,1,-1,-1) C8,2 (1,1,-1,-1,1,1,-1,-1) C16,5 (1,1,-1,-1,1,1,-1,-1,-1,-1,1,1,-1,-1,1,1) C16,6 (1,1,-1,-1,-1,-1,1,1,1,1,-1,-1,-1,-1,1,1) C8,3 (1,1,-1,-1,-1,-1,1,1) C16,7 (1,1,-1,-1,-1,-1,1,1,-1,-1,1,1,1,1,-1,-1) C16,8 (1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1) C8,4 (1,-1,1,-1,1,-1,1,-1) C16,9 (1,-1,1,-1,1,-1,1,-1,-1,1,-1,1,-1,1,-1,1) C16,10 (1,-1,1,-1,-1,1,-1,1,1,-1,1,-1,-1,1,-1,1) C8,5 (1,-1,1,-1,-1,1,-1,1) C16,11 (1,-1,1,-1,-1,1,-1,1,-1,1,-1,1,1,-1,1,-1) C16,12 (1,-1,-1,1,1,-1,-1,1,1,-1,-1,1,1,-1,-1,1) C8,6 (1,-1,-1,1,1,-1,-1,1) C16,13 (1,-1,-1,1,1,-1,-1,1,-1,1,1,-1,-1,1,1,-1) 23 Orthogonal codes usage example 24 1 1 1 0 User data Channelization code C4,2 Coded signal wrong code right code C4,1 C4,2 Decoded signal Integrator???? Result 1 0 1 1 24
Orthogonal codes usage example Multiuser spreading - Downlink 25 0 0 1 0 A User data B 1 1 0 0 C4,2 C4,1 XOR Composite spread signal Received signal C4,2 C4,1 Despreading Integrator 0 0 1 0 Result 1 0 0 1 25 Scrambling codes (pseudo-noise codes) Gold codes (long codes): Code length 38400 chips (10 ms 1 frame) Number of codes available: Downlink 8192 codes (512 sets with 16 codes) 1 primary + 15 secondary codes per set Uplink 16777232 codes Allow to separate: UPLINK - Separate terminals for transmission toward DOWNLINK - Separate for transmission toward UE 26 26
WCDMA codes usage example 27 Cell 1 Cell 2 Ccu1 + Csbs1 Ccu1 + Csbs2 BS 1 UE 1 UE 3 BS 2 Cc + Csu1 Cc + Csu3 Ccu2 + Csbs1 Ccu2 + Csbs2 Cc + Csu2 Cc + Csu4 UE 2 Ccu channelization code for user Csbs - Cell scrambling code Csu - Scrambling code for user Cc Channelization code UE 4 27 Power control mechanisms 28 28
Power control 29 The key goals of power control are to: Provide each UE with sufficient signal quality regardless of the link condition or distance to the BTS Compensate for channel degradation such as fast fading and attenuation Optimize power consumption and hence battery life in the UE Minimize interferences by limited power radiation in radio interface Power control in a WCDMA system is crucial for its successful operation 29 Near-far effect 30 Rx level 1/2/3 Tx level 1 Tx level 2 Tx level 3 UE 1 UE 2 UE 3 Without power control: Tx level 1 = Tx level 2 = Tx level 3 Rx level 1 < Rx level 2 < Rx level 3 With power control: Tx level 1 > Tx level 2 > Tx level 3 Rx level 1 = Rx level 2 = Rx level 3 30
Power control mechanisms 31 Open loop (UL) Open loop (DL) Outer loop (DL) Outer loop (UL) Inner loop (DL) Inner loop (UL) (closed loop) (closed loop) 31 Open loop power control 32 Uplink Open loop aim: Ensure new connections are established causing minimum interferences with minimum power (UE energy save) Downlink Open loop aim: Maximizing cell capacity by minimizing the power used to setup a connection Mechanism is used for establishing the power required for: Access Preamble (and first RACH message RRC Connection Request) Initial dedicated channels power (DPCCH,DPDCH) - downlink Initial dedicated channels power (DPCCH,DPDCH) - uplink 32
Open Loop for Access Preamble - uplink 1. UE measures Pilot channel 2. UE reads Pilot channel power from Broadcast channels 3. Transmission at calculated power 4. Power is ramped up until response on AICH is achieved P_PRACH = Loss + RTWP + SIR_TARGET_RACH 10logSF CPICH BCCH PRACH AICH 33 33 Open Loop for DPDCH/DPCCH 34 1. UE calculates the initial power value for DPDCH channel 1. calculates the initial power value for DPDCH channel and sends it to the NodeB 2. The power is ramped up until a response is heard or a certain maximum power is reached 2. The power is ramped up until a response is heard or a certain maximum power is reached 3. Response from NodeB is send on DPDCH downlink (Radio Link synchronization) 3. Response from UE is send on DPDCH uplink (Radio Link synchronization) DPDCH DPDCH 34
Outer loop power control Outer loop aim: To keep appropriate QoS for the service by monitoring BLER (checking CRC for TB received by UE/ downlink/uplink) Signal quality is estimated on BLER basis: (by MAC layer) if BLER to bad increase reference SIR_target for Inner loop else decrease reference SIR_target for Inner loop SIR_target parameter is calculated as QoS reference value. 35 35 Outer Loop mechanisms 36 interference 1. Check BLER and 2. calculate new SIR_target SIR_target BLER Level required by application (e.g. 10^-6) T1 T2 T3 T4 T5 Time T1 T2 T3 T4 T5 Time Traffic Traffic 36
Inner loop power control Uplink Inner loop aim: Maintain all connections at a sufficiently good quality level Reduce the total amount of radiated power in the network interferences reduced and battery life increased Downlink Inner loop aim: Minimize the transmission power of the RBS, decrease interferences and increase cell capacity Mechanism is used for controlling the signal power when UE moves toward/away from the RBS. Power control commands are fast enough (1500 times per second) to compensate Raleigh fading. Measurements are done on Pilot bits and temporary SIR is calculated (by physical layer) 37 37 Inner Loop mechanism downlink example 38 SIR_temp_dl 1. UE checks received DPDCH power from NodeB SIR_target 2. UE calculates SIR_temp and compare to SIR_target 3. UE sends increase or decrease feedback T1 T2 Time Traffic 38
UMTS handover types 39 39 WCDMA handover types Handover Cell Change Soft/Softer Hard Intermode Intra-frequency Inter-frequency Inter-RAT Inter-frequency, Intermode and Inter-RAT handovers require Compressed mode 40 40
Handover causes Bad uplink/downlink signal quality Distance Traffic load Higher priority calls setup Change of service Directed retry The is in charge of management of handovers 41 41 Hard handover 42 f1, SUE f2, SSC1 NodeB 1 f2, SSC2 f1, SUE NodeB 2 f1, f2 uplink/downlink frequencies SUE, SSC1, SSC2 Scrambling codes 42
Soft handover f1, SUE f1, SUE 43 Cell sets: Active Monitored Detected f2, SSC1 NodeB 1 f2, SSC2 Macrodiversity NodeB 2 f1, f2 uplink/downlink frequencies SUE, SSC1, SSC2 Scrambling codes 43 Softer handover f2, SSC1 f2, SSC2 44 f1, SUE f1, SUE f1, f2 uplink/downlink frequencies SUE, SSC1, SSC2 Scrambling codes 44
SSDT power control UE on uplink DPCCH chooses NodeB from which to get traffic NodeB 2 NodeB 1 NodeB 3 45 45 SRNS Relocation procedure 46 MSC Iu Iu S S Iur 1 2 Iub Iub Iub NodeB 1 NodeB 2 NodeB 3 NodeB 4 NodeB 5 46
UMTS security mechanisms 47 47 UMTS network access security mechanisms 48 MSC SGSN HLR Temporary ID numbers usage Authentication and Key Agreement Ciphering Data integrity check 48
UMTS authentication vector Key Mng Field AMF Sequence nr SQN Random nr RAND Secret key K f1 f2 f3 f4 f5 MAC XRES CK IK AK AUTN = {SQN AMF MAC} SQN AV = {RAND XRES CK IK AUTN} XOR 49 SQN 49 5 8 Authentication and Key Agreement 50 MSC/VLR HLR/AuC 1 4 2 3 6 8 7 50
Ciphering CK COUNT-C DIRECTION BEARER f8 Ciphering sequence LENGTH Original sequence DIRECTION = 0 CK COUNT-C DIRECTION BEARER f8 Ciphering sequence LENGTH XOR XOR Ciphered sequence 51 51 Data integrity IK COUNT-I DIRECTION FRESH f9 MAC-I Message 52 DIRECTION = 0 IK COUNT-I DIRECTION FRESH f9 XMAC-I Message XMAC-I and MAC-I compare MAC-I 52
Any questions? 53 53 Thank you for your attention. Tomasz Kaczmarczyk, DOTR Ericpol Telecom Sp. z o.o. Tomasz.Kaczmarczyk@ericpol.pl Mobile: +48 663 426 806 54 54
55