Evolution of cellular wireless systems from 2G to 5G th October Enrico Buracchini TIM INNOVATION DEPT.

Transcription

1 Evolution of cellular wireless systems from 2G to 5G 6-13 th October 2017 Enrico Buracchini TIM INNOVATION DEPT.

2 Outline- Part I Wireless mobile systems main concepts GSM & GPRS Overview UMTS R99 main characteristics HSDPA: - Rationale, main characteristics and differences vs R99 - R5 UE categories - HSPA evolution hints

3 A wireless mobile system PSTN / ISDN Other Networks IN Control of Radio Stations (BSC/RNC) Radio Access Web, Internet MSC (Switching & MM) Radio Coverage (BTS, Node B)

4 ACCESS TECHNIQUES FOR MOBILE COMMUNICATIONS FDMA (TACS) P T F TDMA (GSM) P F T CDMA (UMTS) P - Power T - Time F - Frequency P T F

5 Cellular System - Frequency Reuse bandwidth Theoretical Cluster

6 Cluster & channel grouping N A B C D A B D A = { 1, 5, 9,...}

7 Frequency reuse concept B A B A B D C D C D A B A B A C D C D C B A B A B D C D C D

8 Choosing The Cluster Size C Q U A L I T Y A P A CI T Y C S

9 Choosing The Cell Size C A C S = CONSTANT P A C CI OS T Y T R

10 Cell Size A B C B C A B A B C B B A A A C C B B B A A C C C B B A A A C C a) b)

11 Antenna solutions for cellular coverage a) b)

12 Planning the cell size and layout a matter of channel/km2 requirements (traffic constraint) tuning the cell size over a single layer adopting overlapping coverage solutions (umbrella cells)

13 GSM/GPRS

14 GSM FREQUENCIES Up 124 channels Down GSM 900 GSM MHz Up 374 channels Down

15 GSM functions - TDMA access technique BURST TRANSMITTED BY TDMA FRAME (4.6 ms) MOBILE 1 MOBILE 2 MOBILE 8 TIME TIME-SLOT: 577 s SIGNAL BURST: 543 s

16 GSM traffic burst structure Tail bits (guard bits) Stealing flag Guard Time Type Number of Bits T 3 Coded Data 57 S 1 Training Seq. 26 S 1 Coded Data GP Bit

17 The GSM system Architecture & Equipment AuC HLR VLR EIR MS BSS PSTN BTS BSC MSC ISDN Other Netws MS Mobile Station BTS Base Transceiver Station BSC Base Station Controller BSS Base Station Subsystem MSC Mobile Switching Center OMC Operations & Maxz intenance Center SM-SC Short Message Service Center OMC SM-SC HLR Home Location Register VLR \ Center EIR Equipment Identity Register

18 PHASE 1 GSM Standard Evolution (I) Basic Services» Telephony» Emergency calls» Short Message Services (Mobile Terminated & Originated)» Group 3 Fax & CS 9.6 kb/s» Call Forwarding & Barring PHASE 2 New Supplementary Services» Call Waiting & Call Hold» Line Identification & Multi-Party Call» Closed User Group & Advice of Charge

19 PHASE 2+ CS & PS Data Services» HSCSD (High Speed Circuit Switched Data)» GPRS (General Packed Radio Service)» EDGE (Enhanced Data rate for the GSM Evolution) Supplementary Services Other GSM Standard Evolution (II)» CCBS (Completion of Call to Busy Subscriber)» USSD (Unstructured Supplementary Service Data)» Specific services support (e.g. SIM Toolkit)» Mobile Number Portability

20 General Packet Radio Service (GPRS) Class A:PS&CS simultaneously Class B: registration to both PS & CS, but no simultaneous usage Class C: registration & usage alternate HLR VLR RRM MSC SGSN GGSN External Data Network BSC BTS Signalling Data Mobility management Authentication Ciphering Routeing Gateway Mobility management Routeing Encapsulation Two (on 4) implemented coding scheme: CS1 & CS2, for a bit rate of 8 kb/s & 12kb/s per slot For a 4 (DL) +1 (UL) terminal, maximum bit 48kb/s (DL): the effective one is around 40kb/s

21 Enhanced Data rate for the GSM Evolution (EDGE) New modulation scheme to increase the data rate per slot: 8 PSK Both CS (ECSD) & PS (EGPRS) ECSD: up to 32 kb/s x slot & peak rate of 64kb/s EGPRS: up to 59.2 kb/s per slot & peak rate of 384 kb/s New terminals (dual-mode EDGE/GSM) & new transceiver in BTSs

22 UMTS R99

23 UMTS core bands assignment ITU IMT-2000 MSS IMT-2000 MSS MHz EUROPE DECT IMT-2000 MSS IMT-2000 MSS MHz

24 UMTS R99 architecture Node B Iub RNC Iucs 3G MSC/VLR PSTN ISDN BTS Node B Iur Iucs Iups Gs HLR Node B RNC Iups 3G SGSN GGSN Packet Data Networks Node B UTRAN Access Network Gn Core Network

25 FDD (WB-CDMA) technique CDMA (UMTS) P T P - Power T - Time F - Frequency F All the users are on the same frequencies and they are distinguished by means of a code

26 Spread spectrum techniques AWGN CAPACITY WITH LIMITED SPECTRUM C=B log 2 (1 + S/N) [C]=bit/s [B]=Hz S/N=signal to noise ratio A given bit rate R can be obtained through Narrow band and high S/N Wide band and low S/N

27 General characteristics of spread spectrum systems Robustness against jammers and fading Low interception probability Multiple access capability Frequency reuse 1

28 DS-CDMA Users sharing the same band are transmitted simultaneously on the same carrier Users are distinguished each other by means of a code and, the mutual interference is reduced during the decoding process In the DS-CDMA technique, the spreading is obtained multiplying the user signal by the signal associated to a code (a PN sequence or an orthogonal sequence)

29 Direct Sequence-CDMA b(t) c(t) BPSK MOD. x(t) j(t) BPSK DEMOD. z(t) c(t) ~ ~ f o z(t)= b(t)c(t) + j(t) z(t)c(t)= b(t)c 2 (t) + j(t)c(t) = b(t) + j(t)c(t) spread interferer

30 Spreading and de-spreading wideband interference Original signal, band Bn S(f) f Spread signal, band Bw f Expanded signal plus broadband interference in the receiver input f Signals after de-spreading f Signals after the reception filter f

31 The rake receiver i n n correlator phase recovery i j e i X n j e n X channel estimat. i correlator phase recovery propagation channel codes generator channel estimat. receiver

32 TDD (TD-CDMA) technique One Time Slot Energy Codes WB-TDMA/CDMA Time frame with 15 time slots

33 Main parameters UTRA/FDD UTRA/TDD Access technique WCDMA Hybrid WCDMA+TDMA Chip rate Carrier spacing Frame duration 3.84 Mcps (SF FDD:4-256, TDD 1-16) MHz 10 ms N. slot per frame 15 BTS synchronization Not required Not required (advisable) Modulation DL: QPSK DL: QPSK UL: Dual-channel QPSK UL: QPSK Coherent receiver Uplink e downlink Multi-rate Variabile SF + Multi-code + Multi-slot (TDD)

34 Soft Handover and Macrodiversity (WCDMA) UE

35 Softer HO Dedicated Data Channel, Dedicated Packet Channel Sector 1 LC=X RNC LC=Y BTS Sector 2 MS receives from both Sectors the same information at the same time LC = Long Code

36 Soft HO Dedicated Data Channel LC=X MS receives from both BTS the same information at the same time LC=Y BTS 1 BTS 2 RNC LC = Long Code

37 Macrodiversity Node B 1 circuit 2 circuit 1 RNC UMSC Node B 2 Frame selection

38 Soft Handover and macrodiversity CPICH Received power CELL A Signal margin CELL C Soft Handover region CELL B Time margin ADD threshold DROP threshold TIME

39 Soft capacity & cell dynamic Cell with radius R and N users N C/I 1/N N+X N We assume that the user density increase: Cell with radius R and (N+X) N users (C/I) 1/(N+X) C/I In the new load situation if we want to stick to the original C/I target we have to reduce the cell radius

40 Capacity: single cell, perfect PC E b I o = CT I/W = C/R I/W C = user signal power R = bit rate W = spreading bandwidth In case of perfect power control I=C(N-1) E b I o C/R W = =. C(N-1)/W R 1 (N-1) (N-1) W =. R 1 E b /I o

41 Exploitation of source activity and sectorization d: source activity factor (for voice, the ideal value is 0.38, actually, a typical assumption is 0.5) G sect : sectorization gain ( for three sectored antenna) N W. R 1 E b /I o. 1. Gsect Site capacity d

42 Capacity: multiple cell Intercell interference is taken into account introducing a factor usually indicated with f or i and defined as: f = (other cell interference)/(intracell interference) N W. R 1 E b /I o. 1.. Gsect 1/(1+f) d f, changes according to the scenario (typical values ); f, is sometimes known as reuse factor of the CDMA system

43 Cell dynamic I 0 Eb N 0 1+ q W Rb 1+ i ms N W 0 + j S = signal power q S NW 0 i = intercell interference to intracell interference ratio j = external interference referred to the thermal noise power m = number of coninuously active users

44 The pole of q is reached when m = m max ) ( b E b N I R W j q m max m b E b N I R W i m 0 0 max + ) ( ) (1 + ) (1 + N I E i m R W j N I E q b b b

45 Example of signal to noise ratio ( q ) versus the load 5 q [db] h W E = 128 b R b I 0 + N 0 = 7 db j = 0

46 W-CDMA Radio Resource Management RRM role Quality of Service control Call Admission Control and Traffic measurement Handover Power control Packet scheduling RNC power control power and load control power control handover control admission and load control packet scheduling 46

47 Admission Control (up-link algorithm) The Admission Control works through a soft limit, introduced to keep the inteference within a given threshold I I TOT I TH Threshold from the cell planning Evaluation of the interference step Interference level I TH Power-based UL noise rise 1 noise rise I TOT I L maximum Noise Rise (evaluated) Load Throughput-based i E b / N 0 i η UL R i (1 f ) W i 47

48 Congestion Control (functional scheme) Events modifying the operative status: resources are re-negotiated by the active calls the modification of the interference conditions the modification of the propagation conditions and power configuration The control is acting on: load congestion control action congestion resolved congestion threshold the interference on the up link the power generated on the down link histeresis time Specific actions on: call admission cell ray BLER radio bearer configuration inter frequency handover reporting period 48

49 Packet scheduling flows Scheduling options Fair throughput (strict RR) Fair resource (time, power, codes) (unfair throughput, depending on the channel status) C/I based: priority to the users experimenting the best channel quality scheduler channel 49 Max C/I: within the Transmission Time Interval, just users experimenting the max values of C/I (high delay for badly served users) Proportional fair resource: uses the control quality estimation and the remaining work

50 Radio Interface - protocol architecture (3gpp ) L3 C-plane RRC U-plane L2/MAC RLC RLC RLC RLC Logical channels L1 MAC Physical Layer Transport channels 50

51 MAC Services and Functions set-up, release of logical channels data transfer service on logical channels allocation/re-allocation of radio resources measurement report Functions Selection of the transport format Handling of priority within one user/between users Scheduling of control messages (broadcast, paging, notification) Multiplexing/de-multiplexing of higher layers PDUs DCH DCH DCH Coding and multiplexing mapping DCH DCH Coding and multiplexing mapping on/from common or dedicated transport channels phy ch phy ch phy ch Contention control on the random access channel 51

52 Retransmission Protocol - services and functions Layer 2 connection set-up and release transparent data transfer unacknowledged data transfer acknowledged data transfer Services of RLC Functions RCLP PDU RCLP PDU RCLP PDU 160 bit 160 bit 160 bit 10ms 10ms 32kbit/s 16kbit/s connection control segmentation and re-assembly error detection/recovery and in-sequence delivery transfer of user data flow control duplicate detection QoS adaptation 52

53 Radio Resource control - services and functions Broadcast of information provided by the Core Network related to the access segment Set-up, maintenance and release of an RRC connection Set-up, maintenance and release of radio bearers on the user plane Assignment, reconfiguration and release of radio resources for the connection Arbitration of radio resource allocation between cells RRC connection mobility functions Quality of Service control and radio resource allocation among the cells Admission and congestion control Control of the MS measurement reporting 53

54 Quality of Service (mapping of the traffic casses on the RABs) CS Domain PS Domain conversational streaming interactive background TM RLC UM RLC TM RLC UM RLC AM RLC AM RLC AM RLC DCH DCH DCH DCH DCH RACH/FACH DCH Real Time traffic Non Real Time traffic 54

55 Radio Access Bearers (RAB) - 3GPP TE MT UTRAN CN EDGE NODE End-to-End Service CN Gateway TE TE/MT Local Bearer Service UMTS Bearer Service External Bearer Service Radio Access Bearer Service CN Bearer Service Each RAB is assigned: the traffic class (e.g. interactive), the max bit rate, the delay, the error rate, the residual error rate, the comm. Domain (CS, PS), the supported application (e.g. voice) Radio Bearer Service UTRA FDD/TDD Service Iu Bearer Service Physical Bearer Service Backbone Bearer Service The RAB is mapped on a Radio Bearer by setting-up the suited parameters for the Physical and Layer 2 protocols 55

56 RAB as function of the service class - 3GPP TS Service class Conversational (e.g. with adaptive encoding) Conversationall (e.g. video call) Peak bit rate [kbit/s] Residual BER Delay sensitivity Transport Channel 4,75 12, Sensitive to delay DCH and Jitter 64; 128; Sensitive to delay DCH and Jitter Domain Circuit Circuit Streaming 57, Sensitive to Jitter DCH Circuit Streaming Sensitive to Jitter DCH Packet Interattive or Background Interattive or Background Moderate DCH sensitivity to delay Moderate HSsensitivity to delay DSCH * Packet Packet * High Speed DL Shared Channel, used with the HSDPA (High Speed Downlink Packet Access) feature, introduced with Release 5 UMTS 56

57 UMTS- HSDPA (R5)

58 HSDPA positioning vs other solutions 10 Mbit/s WLAN (802.11b) HSDPA (UMTS Release 5) 1 Mbit/s UMTS Release kbit/s Velocità bit rate di Trasmissione cell Raggio radius Cella EDGE GPRS 100 m 1000 m 10 km

59 HSDPA rationale to improve data speeds per user High speed download (mails, video and mp3) Video streaming Highly interactive games High speed browsing to improve service latency to improve Network Capacity The HSPA deployment is based on the reuse of 3G network infrastructure: same NodeB (modified) and RNC same Core Network same site/mast/antennas.

60 3GPP HSDPA Rel.5 Introduced in 3GPP Release 5 Main Characteristics vs R99:» Shared packet transmission» Higher order modulation (16QAM)» Shorter TTI (2ms vs 10ms)» Adaptive modulation & coding» Fast Link Adaptation» Fast Hybrid HARQ» Advanced packet scheduling

61 HSDPA the innovative capabilities Single transmission channel shared among several users on the down link Scheduling of the transmission queues performed by the base station; MAC layer partially decentralised Multiplexing over the time domain (TTI - 2 ms) Hybrid techniques (H-ARQ, Hybrid ARQ) for corrupted radio blocks, managed by the B-node Adaptive modulation and coding, based on a channel quality indicator (CQI) transmitted by the mobile Use of 16-QAM modulation to increase the spectral efficiency whenever under good channel conditions Bit rate up to14 Mbit/s.

62 HSDPA: Main characteristics vs UMTS R99

63 Fast Scheduling and CQI the CQI principle Nodo B Mobile 2 Mobile 1 Decision on sheduling and AMC* The CQI (Channel Quality Indicator) is derived by the MS every 2 ms on the basis of the pilot channel (CPICH). It specifies: power, modulation and coding scheme the MS is ready to receive for the subsequent TTI, to maintain a Block Error Rate (BLER) lower than 10% * Adaptive Modulation & Coding 63

64 R5 UE categories UE categories defined on the basis of: 1) Number of codes that can be elaborated per each TTI 2) Maximum bit rate over the entire frame 3) Minimum interval elapsing between two subsequent TTIs 4) Possible modulation schemes (only QPSK, or both QPSK and 16-QAM) 5) Storage dimension for the HARQ, e.g the less powerful class does not accept the Incremental Redundancy at the maximum bit rate. 3GPP TS

65 R5 UE categories and related bit rates Classe class Max. max Num. codes Codici # Minimo minimum intervallo TTI inter-tti interval peak Bit rate bit rate di picco at layer al livello 1 fisico (mbps) [Mbit/s] peak Bit rate bit rate di picco at RLC al livello level RLC (mbps) [Mbit/s] IR al at max peak bit rate bit rate Modulazioni supported modulation supportate ,2 1,1 No QPSK, 16-QAM ,2 1,1 Yes Si QPSK, 16-QAM ,8 1,6 No QPSK, 16-QAM ,8 1,6 Yes Si QPSK, 16-QAM ,6 3,4 No QPSK, 16-QAM ,6 3,4 Yes Si QPSK, 16-QAM ,2 6,7 No QPSK, 16-QAM ,2 6,7 Yes Si QPSK, 16-QAM ,6 No QPSK, 16-QAM ,4 No QPSK, 16-QAM ,9 0,8 No QPSK ,8 1,6 No QPSK 3GPP TS

66 HSPA Evolution hints HSPA Evolution 710 Ericsson White Paper: WP_0710_Ericsson.pdf HSPA+ for Enhanced Broadband Qualcomm WP,

67 Outline- Part II COMING UP SOON NEXT WEEK!!! LTE LTE Advanced 5G overview..stay TUNED

68 Thanks for your kind attention