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Saarbrücken, 06.07.2004 Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Albrecht Kunz Hochschule für Technik und Wirtschaft des Saarlandes.

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Präsentation zum Thema: "Saarbrücken, 06.07.2004 Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Albrecht Kunz Hochschule für Technik und Wirtschaft des Saarlandes."—  Präsentation transkript:

1 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Albrecht Kunz Hochschule für Technik und Wirtschaft des Saarlandes Saarbrücken, 04. Juli 2005 UMTS Air Interface Overview

2 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik All-IP Based Multimedia Terminals The Ultimate Goal If I would have had a mobile multimedia terminal, I could: - look an the e-map where I am - send an for some help - call my wife and kids and send them a picture of this beautiful location - get the latest news from the stockmarket while waiting. It would be great However I dont have a tool like that and Im lost. Im in trouble

3 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Keller Support of push service23.974

4 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Keller Support of push service GPP Technical Specification Groups

5 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Overview Motivation UMTS key characteristics CDMA Basics Multipath reception / Rake receiver TX/RX baseband processing Transport & physical channels Frame structure Handover Power control

6 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik UMTS Key Characteristics

7 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Quality of Service (QoS) - End to End delay «Hi ! How are you ?» «Hi ! How... T small delays (10-20 ms) are not annoying for users delay < 200 to 400 ms, the effectiveness of the interaction is lower but can be still acceptable delay is > 400 ms, interactive voice communication is quite difficult

8 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Digitaltechnik.ppt : 8 UMTS Terrestrial Radio Access (UTRA) TDD modeFDD mode Frequency Division Duplex based on Alpha Concept (DS-CDMA) Time Division Duplex based on Delta Concept (TD-CDMA)

9 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Air Interface Characteristics time Frequency time Frequency TDD mode FDD mode Energy, Code

10 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik UMTS frequency bands ' 1 2 UMTS TDD (1900MHz-1920MHz,2010MHz-2025MHz) UMTS uplink (FDD) (1920MHz-1980MHz) UMTS downlink (FDD) (2110MHz-2170MHz) [MHz] 44 4 UMTS Satellite (1980MHz-2010MHz, 2170MHz-2010MHz)

11 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Frequency reuse R=7R=3R=4 R=1

12 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Multiple Access P t f P t f P t f FDMATDMACDMA

13 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Despreading P t f P t f

14 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Multipath Propagation Environment Propagation Environment h(t, ) Channel Impulse response

15 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Channel model

16 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Rake receiver

17 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik UMTS – Prinzip der Bandspreiztechnik Verwendung orthogonaler Spreizcodes, um die Nutzer in der Zelle zu separieren

18 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Verwendete Modulationsart ist QPSK (downlink, d.h. Kommunikation von der Basisstation zur Mobilstation Codes unterschiedlicher Spreizfaktoren (Spreading Factor, SF) können verwendet werden Die okkupierte Bandbreite ist nach dem Spreizen SF-mal so groß Die spektrale Leistungsdichte wird durch den Spreizvorgang auf 1/SF reduziert Verwendung orthogonaler Spreizcodes: Spreizvorgang

19 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Anwendung eines Korrelators oder Matched Filters: Korrelator: Integration von SF Chips, bei Verwendung des richtigen Codes (phasensynchron zum Sender) tritt Korrelationsspitze auf Matched filter mit Entspreizsequenz (-t): Korrelationsspitze tritt auf bei vollständiger Überlappung von gesendeter Spreizsequenz und multiplizierter Entspreizsequenz Gleichheit der Sequenzen => +1*+1=1 und –1*-1=1 maximales Integrationsergebnis (Korrelationsspitze) ! Unterschiedliche Codes führen zu Nebenzipfeln, da die Codes nicht vollständig orthogonal sind (Bsp: siehe Gold-Codes) Entspreizvorgang: Entspreizen durch Multiplikation mit der gleichen Spreizfunktion, mit der gesendet wurde

20 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Digitaltechnik.ppt : 20 Maximal LFSR Sequences = M-Sequences There are LFSRs with L memory elements and characteristic polynomial Q(x) that produce sequences with maximum period of length 2 L -1. The sequences are called maximal LFSR sequences or m-sequences. The characteristic polynomials are called primitive polynomials. Tables of primitive polynomials exist (e.g. in Peterson/Weldon,Error Correcting Codes,1972). Example: Degree 8 Q(x): 561 octal

21 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Digitaltechnik.ppt : 21 Correlation Properties of M-Sequences The out of phase values of the PACF of m-sequences (after mapping to a bipolar sequence) are all -1: Example: m-sequence of length 15

22 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Digitaltechnik.ppt : 22 Decimation of M-Sequences Definition (decimation): Given a m-sequence b n, generate a new sequence c n by taking every q-th element form b n. Then c n is said to be a decimation by q of b n. If b n is generated by m a (x) with roots a i then c n is generated by m a q (x) with roots a i q. If gcd(q, N) = 1 then c n is also a m-sequence. Example: N = 31 is prime therefore all decimations give m-sequences (some of which may be identical !!)

23 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Digitaltechnik.ppt : 23 Crosscorrelation Properties of Gold-Sequences If L is not 0 mod 4 then pairs of m-sequences exist with three-valued crosscorrelation functions (CCF) these three values are: -1, -t(L), t(L)-2 its called preferred pair !

24 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Digitaltechnik.ppt : 24 Construction of Gold Codes A set of Gold codes of length N is generated based on a preferred pair of m-sequences of the same length. The second m-sequence is generated from the first by decimation with the factor t(L). The set size is N+2 = 2 L +1. N different sequences in the set are generated by the binary addition of sequence 1 with all cyclic shifts of sequence 2. The original sequences are added to the set giving a set size of N+2. initial value determines output sequence LFSR for m-sequence 2 LFSR for m-sequence 1 Gold code

25 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Digitaltechnik.ppt : 25 Correlation properties of Gold Codes Gold codes have three valued out of phase periodic autocorrelation function and even periodic crosscorrelation function: g 1 (x) = x 5 + x and g 2 (x) = x 5 + x 4 + x 2 + x + 1 Example: Gold Codes of length N=31, L = 5, with Generator polynomials The three out of phase correlation values are -1, -9 and 7

26 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Digitaltechnik.ppt : 26 Gold Codes of Length Segments of length of Gold codes of length are used in the WCDMA system (DL DPDCH/DPCCH). Example: Generator polynomials: g 1 (x) = x 18 + x 5 + x 2 + x + 1 = m 1 (x) g 2 (x) = x 18 + x 17 + x 13 + x 12 + x 9 + x 8 + x 6 + x + 1 = m 1025 (x) The second sequence is generated by decimating the first sequence with factor 2 (L+2)/2 +1 = 1025.

27 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Digitaltechnik.ppt : 27 Orthogonal Gold-Codes For many Gold-Codes or Gold like codes of length 2 L -1 the crosscorrelation value at phase 0 is -1. If these codes are suitably extended by one chip the crosscorrelation value at phase 0 is 0. Therefore the codes are orthogonal !! g 1 (x) = x 8 + x 6 + x 5 + x and g 2 (x) = x 8 + x 4 + x 3 + x Original codes have length 255. Orthogonal codes have length 256 by addition of the chip -1. Out of phase correlation properties change due to the extension bit. Example: L = 8

28 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Digitaltechnik.ppt : 28 Correlation Properties of Gold like Codes of length 255

29 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Digitaltechnik.ppt : 29 Correlation Properties of Orthogonal Gold-Codes of Length 256 =0 --> orthogonal !

30 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Downlink scrambling code generator InIn QnQn X Y

31 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Digitaltechnik.ppt : 31 spreading /modulation for downlink DPCH -chiprate 3.84 Mcps - pulse-shaping Root-Raised Cosine (RRC) with a= QPSK modulation p(t) IQ Mux DPDCH/DPCCH cos( t) p(t) sin( t) c ch c scramb 16*2 K kbps3.84 Mcps

32 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik spreading /modulation for uplink DPCH -chiprate 3.84 Mcps - pulse-shaping Root-Raised Cosine (RRC) with a= Dual BPSK modulation *G Anpassungsfaktor

33 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik RRC Impulse Response

34 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Transport / Logical Channels Physical Channels BCH FACH PCH RACH CPCH DCH DSCH Common Pilot Channel Primary Common Control Physical Channel Secondary Common Control Physical Channel Physical Random Access Channel Physical Common Packet Channel Dedicated Physical Data Channel Dedicated Physical Control Channel Synchronization Channel Physical Downlink Shared Channel Page Indication Channel Acquisition Indication Channel Mapping of Transport Channels

35 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Structure of Uplink Dedicated Channels slot #0slot #1slot #islot #14 frame #0frame #1frame #iframe #71 T f =10 ms T super =720 ms DPDCH Data1 N data bits DPCCH Pilot N TFCI bits TFCI N TFCI bits T s =2560 chips, 10*2 k bits, k=0..7 FBI N FBI bits TPC N TPC bits

36 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Structure of Downlink Dedicated Channels slot #0slot #1slot #islot #14 frame #0frame #1frame #iframe #71 T f =10 ms T super =720 ms Pilot N pilot bits TFCI N TFCI bits TPC N TPC bits Data1 N data bits Data2 N data bits T s =2560 chips, 10*2 k bits, k=0..7 DPCCHDPDCH DPCCH

37 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Multicode Downlink Transmission PilotTFCITPC DPCH 1 Data1Data2 Transmission Power DPCH 2 Data1Data2 DPCH n Data1Data2

38 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Multicode Uplink Transmission DPCCH PilotTFCIFBITPC DPDCH 1 Data DPDCH n Data DPDCH 2 Data

39 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik coding and multiplexing of Transport Channels (TC) The output after inner (intra-frame ) interleaving is typically mapped to one DPDCH. Only for highest bit rates the output is mapped to several DPDCHs (multi-code transmission)

40 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Convolutional coder

41 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Random Access Transmission 10 ms, chips Message P1P1 PjPj P0P0 Preamble 4096 chips

42 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik RACH Message Part slot #0slot #1slot #islot #14 T s =2560 chips, 10*2 k bits, k=0..3 T RACH =10 ms Data Control Pilot N TFCI bits TFCI N TFCI bits Data N data bits

43 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Acquisition Indication Channel AS #0AS #1AS #iAS #14 2*T f =20 ms 4096 chips 1024 chips AIempty

44 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Timing relationrelationship between preambles, AICH message One accessslot p-a p-m p-p Pre- amble Pre- amble Message part Acq. Ind. AICH access slots RXat UE PRACH access slots TXat UE

45 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Common Pilot Channel Pre-defined symbol sequence N TFCI bits T s =2560 chips, 10*2 k bits, k=0..7 slot #0slot #1slot #islot #14 frame #0frame #1frame #iframe #71 T f =10 ms T super =720 ms

46 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Primary Common Pilot Channel Characteristics of the primary common pilot channel –The same channelization code is always used –Scrambled by the primary scrambling code –One per cell –Broadcast over entire cell The primary common pilot channel is the phase reference for SCH, P-CCPCH, AICH, PICH and the default phase reference for all other downlink physical channels.

47 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Secondary Common Pilot Channels Characteristics of the secondary common pilot channel –usage of an arbitrary channelization code of SF=256 –scrambled by either the primary or secondary scrambling code –zero, one or several per cell –may be transmitted over only a part of the cell A secondary common pilot channel may be the phase reference for the secondary CCPCH and the downlink DPCH

48 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Synchronization Channel ac p ac s i,0 Slot #0 256 chips 2560 chips ac p ac s i,1 Slot #1 ac p ac s i,14 Slot #14 1 frame, 10 ms, chips Primary SCH Secondary SCH

49 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Physical Downlink Shared Channel slot #0slot #1slot #islot #14 frame #0frame #1frame #iframe #71 T f =10 ms T super =720 ms Data N data bits T s =2560 chips, 20*2 k bits, k=0..6

50 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Power control (1) Outer loop (closed loop) - adjust SIR target for inner loop Inner loop (closed loop) -SIR controlled -user oriented -for fast Power Control Open loop for RACH

51 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Power control (2)

52 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Power control - inner loop adjust TX power of BS and MS to reduce near-far effect Example (DL): MS estimates received power S RX of DPCCH after Rake combining MS estimates downlink interference I DL SIR est = S RX / I DL generate transmit power control (TPC) command according to SIR est > SIR target,DL ----> TPC = down SIR est TPC = up BS increases power by D TPC dBs

53 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Power control - TPC generation BS: all base stations in the active set send TPC commands based on a quality measurement BS: threshold for TPC is controlled in the outer loop by the network node MS: power up if TPC bits received of all BS indicate an upward step MS: power down if TPC bits received of at least one BS indicate downward step

54 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Power control - open loop (1) Control RACH TX power uses –pathloss –SIR target broadcast by BCCH –Uplink interference level broadcast by BCCH –transmit power of CCPCH

55 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Handover concept SNR estimation[dB] Time Active set hysteresis threshold Replace B with C Remove A A A connected Active set replace hyteresis Replace C with B B C Add B to active set

56 Saarbrücken, Standardisierung UMTS Dienste FB E - Telekommunikationselektronik TPC evaluation 32 SIR Target


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