WCDMA FDD Mode Transmitter. Dr. Chih-Peng Li ( 李 )

Transcription

1 WCDMA FDD Mode Transmitter Dr. Chih-Peng Li ( 李 )

2 Table of Contents Traditional Sequential ASIC Design Flow Introduction to WCDMA Transmitter Specifications WCDMA Network Architecture Physical Layer General Description Multiplexing and Channel Coding (MCC) WCDMA Uplink Physical Layer WCDMA Downlink Physical Layer

3 References 3GPP Technical Specification (Release 999, 5 Series) WCDMA for UMTS Radio Access For Third Generation Mobile Communications -- by Harri Holma and Antti Toskala, Artech House, Wireless Communications - Principles & Practice -- by Theodore S. Rappaport, Prentice Hall, nd Edition, Dec. 3, 3

4 Traditional Sequential ASIC Design Flow 4

5 Traditional Sequential ASIC Design Flow Specification System Models Architecture Design RTL Design Functional Verification RTL Design Logical Synthesis Timing Verification P & R Physical Verification Logic synthesis Physical Design Prototype Build & Test 5 Prototype

6 WCDMA Network Architecture 6

7 Network Elements in a WCDMA PLMN Uu Iu Node B USIM RNC MSC/VLR GMSC PLMN, PSTN ISDN, etc. Node B Cu Iub Iur HLR Node B ME RNC SGSN GGSN Internet Node B UE UTRAN Core Network External Networks PLMN: Public Land Mobile Network. One PLMN is operated by a single operator. 7

8 User Equipment (UE) The UE consists of two parts: The Mobile Equipment (ME) is the radio terminal used for radio communication over the Uu interface. The UMTS Subscriber Identity Module (USIM) is a smartcard that holds the subscriber identity, performs authentication algorithms, and stores authentication and encryption keys and some subscription information that is needed at the terminal. UTRAN consists of two distinct elements: The Node B converts the data flow between the Iub and Uu interfaces. It also participates in radio resource management. The Radio Network Controller (RNC) owns and controls the radio resources in its domain (the Node Bs connected to it). RNC is the service access point for all services UTRAN provides the core network (CN). 8

9 9 WCDMA System Architecture UMTS system utilizes the same well-known architecture that has been used by all main nd generation systems. The network elements are grouped into: The Radio Access Network (RAN, UMTS Terrestrial RAN = UTRAN) that handles all radio-related functionality. The Core Network (CN) which is responsible for switching and routing calls and data connections to external networks. Both User Equipment (UE) and UTRAN consist of completely new protocols, which is based on the new WCDMA radio technology. The definition of CN is adopted from GSM.

10 Main Elements of the GSM Core Network HLR (Home Location Register) is a database located in the user s home system that stores the master copy of the user s service profile. The service profile consists of, for example, information on allowed services, forbidden roaming areas, and Supplementary Service information such as status of call forwarding and the call forwarding number. It is created when a new user subscribes to the system. HLR stores the UE location on the level of MSC/VLR and/or SGSN.

11 Main Elements of the GSM Core Network MSC/VLR (Mobile Services Switching Center / Visitor Location Register) is the switch (MSC) and database (VLR) that serves the UE in its current location for circuit switched services. The MSC function is used to switch the CS transactions. The VLR function holds a copy of the visiting user s service profile, as well as more precise information on the UE s location within the serving system.

12 Main Elements of the GSM Core Network GMSC (Gateway MSC) is the switch at the point where UMTS PLMN is connected to external CS networks. All incoming and outgoing circuit switched connections go through GMSC. SGSN (Serving GPRS (General Packet Radio Service) Support Node) functionality is similar to that of MSC/VLR, but is typically used for Packet Switched (PS) services. GGSN (Gateway GPRS Support Node) functionality is close to that of GMSC but is in relation to PS services.

13 Interfaces Cu Interface: this is the electrical interface between the USIM smartcard and the ME. The interface follows a standard format for smartcards. Uu Interface: this is the WCDMA radio interface, which is the subject of the main part of WCDMA technology. This is also the most important open interface in UMTS. Iu Interface: this connects UTRAN to the CN. Iur Interface: the open Iur interface allows soft handover between RNCs from different manufacturers. Iub Interface: the Iub connects a Node B and an RNC. UMTS is the first commercial mobile telephony system where the Controller-Base Station interface is standardized as a fully open interface. 3

14 WCDMA Physical Layer General Description (3GPP TS 5.) 4

15 Elements of A Digital Communications System From Other Sources Information Bits Source Bits Channel Bits Format Digital Input m i Digital Output mˆ i Source Encoding Encryption Channel Encoding Bit Stream Interleaving Multiplexing Modulation (t) s i Synchronization ˆ ( t) s i Frequency Spreading Digital Waveform Multiple Access TX RF PA C H A N N E L Format Source Decoding Decryption Channel Decoding Deinterleaving Demultiplexing Demodulation Frequency Despreading Multiple Access RX RF IF Information Sink Source Bits Optional Essential Channel Bits To Other Destinations 5

16 3GPP (Radio Access Network) RAN Specifications TS 5. Physical Layer general description Describes the contents of the layer documents (TS 5. series); where to find information; a general description of layer. TS 5. Physical channels and mapping of transport channels onto physical channels (FDD) Establishes the characteristics of the layer- transport channels and physical channels in the FDD mode, and specifies: Transport channels Physical channels and their structure Relative timing between different physical channels in the same link, and relative timing between uplink and downlink; Mapping of transport channels onto the physical channels. 6

17 3GPP (Radio Access Network) RAN Specifications TS 5. TS 5.3 Multiplexing and Channel Coding (FDD) Spreading and Modulation (FDD) Describes multiplexing, channel coding, and interleaving in the FDD mode and specifies: Coding and multiplexing of transport channels; Channel coding alternatives; Coding for layer control information; Different interleavers; Rate matching; Physical channel segmentation and mapping; Establishes the characteristics of the spreading and modulation in the FDD mode, and specifies: Spreading; Generation of channelization and scrambling codes; Generation of random access preamble codes; Generation of synchronization codes; Modulation; 7

18 3GPP (Radio Access Network) RAN Specifications TS 5.4 Physical Layer Procedures (FDD) Establishes the characteristics of the physical layer procedures in the FDD mode, and specifies: Cell search procedures; Power control procedures; Random access procedure. TS 5.5 Physical Layer Measurements (FDD) Establishes the characteristics of the physical layer measurements in the FDD mode, and specifies: The measurements performance by layer ; Reporting of measurements to higher layers and network; Handover measurements and idle-mode measurements. 8

19 General Protocol Architecture Radio interface means the Uu point between User Equipment (UE) and network. The radio interface is composed of Layers, and 3. Layer 3 Radio Resource Control (RRC) Layer Control / Measurements Medium Access Control Logical channels Transport channels Layer Physical layer 9

20 General Protocol Architecture The circles between different layer/sub-layers indicate service access points (SAPs). The physical layer offers different transport channels to MAC. A transport channel is characterized by how the information is transferred over the radio interface. MAC offers different logical channels to the radio link control (RLC) sub-layer of Layer. A logical channel is characterized by the type of information transferred.

21 Transport Channels Transport channels are services offered by Layer to the higher layers. A transport channel is defined by how and with what characteristics data is transferred over the air interface. Two groups of transport channels: Dedicated Transport Channels Common Transport Channels

22 Dedicated Transport Channels Transport channels DCH Dedicated Channel (only one type) Common Transport Channels divided between all or a group of users in a cell (no soft handover, but some of them can have fast power control) BCH: Broadcast Channel FACH: Forward Access Channel PCH: Paging Channel RACH: Random Access Channel CPCH: Common Packet Channel DSCH: DL Shared Channel

23 Dedicated Transport Channels There exists only one type of dedicated transport channel, the Dedicated Channel (DCH) The Dedicated Channel (DCH) is a downlink or uplink transport channel. The DCH is transmitted over the entire cell or over only a part of the cell using e.g. beam-forming antennas. DCH carries both the service data, such as speech frames, and higher layer control information, such as handover commands or measurement reports from the terminal. Possibility of fast rate change (every ms) Support of fast power control and soft handover. 3

24 Common Transport Channel Broadcast Channel (BCH) -- mandatory BCH is a downlink transport channel that is used to broadcast system and cell specific information. BCH is always transmitted over the entire cell. The most typical data needed in every network is the available random access codes and access slots in the cell, or the types of transmit diversity. BCH is transmitted with relatively high power. Single transport format a low and fixed data rate for the UTRA broadcast channel to support low-end terminals. 4

25 Common Transport Channel Paging Channel (PCH) -- mandatory PCH is a downlink transport channel. PCH is always transmitted over the entire cell. PCH carries data relevant to the paging procedure, that is, when the network wants to initiate communication with the terminal. The identical paging message can be transmitted in a single cell or in up to a few hundreds of cells, depending on the system configuration. 5

26 Common Transport Channel Random Access Channel (RACH) -- mandatory RACH is an uplink transport channel. RACH is intended to be used to carry control information from the terminal, such as requests to set up a connection. RACH can also be used to send small amounts of packet data from the terminal to the network. The RACH is always received from the entire cell. The RACH is characterized by a collision risk. RACH is transmitted using open loop power control. 6

27 7 Common Transport Channel Forward Access Channel (FACH) -- mandatory FACH is a downlink transport channel. FACH is transmitted over the entire cell or over only a part of the cell using e.g. beam-forming antennas. FACH can carry control information; for example, after a random access message has been received by the base station. FACH can also transmit packet data. FACH does not use fast power control. FACH can be transmitted using slow power control. There can be more than one FACH in a cell. The messages transmitted need to include in-band identification information.

28 Common Transport Channel Common Packet Channel (CPCH) -- optional CPCH is an uplink transport channel. CPCH is an extension to the RACH channel that is intended to carry packet-based user data. CPCH is associated with a dedicated channel on the downlink which provides power control and CPCH Control Commands (e.g. Emergency Stop) for the uplink CPCH. The CPCH is characterised by initial collision risk and by being transmitted using inner loop power control. CPCH may last several frames. 8

29 Common Transport Channel Downlink Shared Channel (DSCH) -- optional DSCH is a downlink transport channel shared by several UEs to carry dedicated user data and/or control information. The DSCH is always associated with one or several downlink DCH. The DSCH is transmitted over the entire cell or over only a part of the cell using e.g. beam-forming antennas. DSCH supports fast power control as well as variable bit rate on a frame-by-frame basis. 9

30 Transport Channels DCH Mapping of Transport Channels onto Physical Channels Physical Channels Dedicated Physical Data Channel (DPDCH) Dedicated Physical Control Channel (DPCCH) RACH CPCH BCH FACH PCH DSCH Unmapped Physical Random Access Channel (PRACH) Physical Common Packet Channel (PCPCH) Primary Common Control Physical Channel (P-CCPCH) Secondary Common Control Physical Channel (S-CCPCH) Physical Downlink Shared Channel (PDSCH) Common Pilot Channel (CPICH) Synchronization Channel (SCH) Acquisition Indicator Channel (AICH) Access Preamble Acquisition Indicator Channel (AP-AICH) Paging Indicator Channel (PICH) CPCH Status Indicator Channel (CSICH) Collision-Detection/Channel-Assignment Indicator Channel 3 (CD/CA-ICH)

31 Multiplexing and Channel Coding ( 3GPP TS 5. ) 3

32 UL Multiplexing and Channel Coding 3

33 DL Multiplexing and Channel Coding 33

34 CRC-attachment CRC-Attachment For error detection g CRC4 (D) = D 4 + D 3 + D 6 + D 5 + D + g CRC6 (D) = D 6 + D + D 5 + g CRC (D) = D + D + D 3 + D + D + g CRC8 (D) = D 8 + D 7 + D 4 + D 3 + D + TrBk TrBk 34

35 35 Channel Coding Usage of coding scheme and coding rate Type of TrCH BCH PCH RACH CPCH, DCH, DSCH, FACH Coding scheme Convolutional coding Turbo coding No coding Coding rate / /3, / /3

36 WCDMA Uplink Physical Layer ( 3GPP TS 5. & 5.3 ) 36

37 Configuration Radio frame Overview A radio frame is a processing unit which consists of 5 slots. The length of a radio frame corresponds to 384 chips. Time slot A time slot is a unit which consists of fields containing bits. The length of a slot corresponds to 56 chips. Spreading Modulation: QPSK. Data Modulation: BPSK. Spreading Two-level spreading processes 37

38 Spreading (cont.) Channelization operation OVSF codes. Overview Transform every data symbol into a number of chips. Increase the bandwidth of the signal. The number of chips per data symbol is called the Spreading Factor. Data symbols on I- and Q-branches are independently multiplied with an OVSF code. Scrambling operation Long or short Gold codes. Applied to the spread signals. Randomize the codes Spread signal is further multiplied by complex-valued scrambling 38

39 Uplink Physical Channels Dedicated Uplink Physical Channels Uplink Dedicated Physical Data Channel (UL DPDCH) Uplink Dedicated Physical Control Channel (UL DPCCH) Common Uplink Physical Channels Physical Random Access Channel (PRACH) Physical Common Packet Channel (PCPCH) 39

40 Dedicated Uplink Physical Channels UL Dedicated Physical Data Channel (UL DPDCH) Carry the DCH transport channel (generated at Layer and above). There may be zero, one, or several uplink DPDCHs on each radio link. UL Dedicated Physical Control Channel (UL DPCCH) Carry control information generated at Layer One and only one UL DPCCH on each radio link. 4

41 4 Frame Structure for UL DPDCH/DPCCH DPDCH Data N data bits T slot = 56 chips, N data = * k bits (k=,,,6) DPCCH Pilot N pilot bits TFCI N TFCI bits FBI N FBI bits TPC N TPC bits T slot = 56 chips, bits One Power Control Period Slot # Slot # Slot #i Slot #4 radio frame: T f = ms = 384 chips

42 UL DPDCH The parameter k determines the number of bits per uplink DPDCH slot. It is related to the spreading factor SF of the DPDCH as SF = 56/ k. The DPDCH spreading factor ranges from 56 down to 4. Slot Format #i Channel Bit Rate (kbps) Channel Symbol Rate (ksps) SF Bits/ Frame Bits/ Slot N data

43 43 UL DPCCH - Layer Control Information The spreading factor of the uplink DPCCH is always equal to 56, i.e. there are bits per uplink DPCCH slot. Slot Form at #i A B A B A 5B Channel Bit Rate (kbps) Channel Symbol Rate (ksps) SF Bits/ Frame Bits/ Slot N pilot N TPC N TFCI N FBI Transmitted slots per radio frame

44 UL DPCCH - Layer Control Information Pilot Bits. Support channel estimation for coherent detection. Frame Synchronization Word (FSW) can be sued to confirm frame synchronizaton. Transmit Power Control (TPC) command. Inner loop power control commands. Feedback Information (FBI). Support of close loop transmit diversity. Site Selection Diversity Transmission (SSDT) Transport-Format Combination Indicator (TFCI) optional TFCI informs the receiver about the instantaneous transport format combination of the transport channels. 44

45 45 Pilot Bit Patterns with N pilot =3,4,5,6 Slot # Bit # N pilot = 6 N pilot = 5 N pilot = 4 N pilot = 3 Shadowed column is defined as FSW (Frame Synchronization Word).

46 46 Pilot Bit Patterns with N pilot =7,8 Shadowed column is defined as FSW (Frame Synchronization Word). Slot # Bit # N pilot = 8 N pilot = 7

47 47 Spreading of UL DPCH c d, β d DPDCH DPDCH 3 c d,3 β d Σ I c d,5 β d DPDCH 5 S lon g,n or S short,n I+jQ c d, β d DPDCH c d,4 β d DPDCH 4 DPDCH 6 c d,6 β d Σ Q DPCCH c c β c j One and only one UL DPCCH. Up to six parallel DPDCHs.

48 48 Spreading of UL DPCH The binary DPCCH and DPDCHs to be spread are represented by real-valued sequences, i.e. the binary value "" is mapped to the real value +, while the binary value "" is mapped to the real value. The DPCCH is spread to the chip rate by the channelization code c c, while the n:th DPDCH called DPDCHn is spread to the chip rate by the channelization code c d,n. One DPCCH and up to six parallel DPDCHs can be transmitted simultaneously, i.e. n 6.

49 Channelization Codes Each CDMA channel is distinguished via a unique spreading code. These spreading codes should have low crosscorrelation values. In 3GPP W-CDMA, orthogonal variable spreading factor (OVSF) codes are used. Preserve the orthogonality between a user s different physical channels. Scrambling is used on top of spreading. 49

50 Code-tree for Generation of Orthogonal Variable Spreading Factor (OVSF) Codes 5 C ch,4, =(,,,) C ch,, = (,) C ch,4, = (,,-,-) C ch,, = () C ch,4, = (,-,,-) C ch,, = (,-) C ch,4,3 = (,-,-,) SF = SF = SF = 4 The channelization codes are uniquely described as C ch,sf,k, where SF is the spreading factor of the code and k is the code number, k SF-.

51 5 Generation of Channelization Codes C ch,, = = =,,,,,,,,,,,, ch ch ch ch ch ch C C C C C C ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) = ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,3,,,,,,, : : : n n ch n n ch n n ch n n ch n ch n ch n ch n ch n ch n ch n ch n ch n n ch n n ch n ch n ch n ch n ch C C C C C C C C C C C C C C C C C C

52 5 OVSF Code Allocation for UL DPCH DPCCH is always spread by c c = C ch,56, When there is only one DPDCH DPDCH is spread by c d, = C ch,sf,k (k= SF / 4) When there are more than one DPDCH All DPDCHs have SF=4 DPDCH n is spread by the the code c d,n = C ch,4,k k = if n {, }, k = 3 if n {3, 4} and k = if n {5, 6}

53 Gain of UL DPCH After channelization, the real-valued spread signals are weighted by gain factors, c for DPCCH and d for all DPDCHs. At every instant in time, at least one of the values c and d has the amplitude.. The -values are quantized into 4 bit words. After the weighting, the stream of real-valued chips on the I- and Q-branches are then summed and treated as a complex-valued stream of chips. This complex-valued signal is then scrambled by the complexvalued scrambling code S dpch,n. 53

54 Gain of UL DPCH Signaling values for β c and β d 54 Quantized amplitude ratios β c and β d Switch off

55 Configuration of Uplink Scrambling Sequence Generator 55 x c long,,n MSB LSB y c long,,n

56 Uplink Long Scrambling Codes Two elementary codes: c long,,n and c long,,n. c long,,n and c long,,n are constructed from position wise modulo sum of 384 chip segments of two binary m-sequences, x and y. x and y are originated from two generator polynomials of degree 5. x sequence: generator polynomial: X 5 +X 3 + y sequence: generator polynomial: y 5 +y 3 +y +y+ The sequence c long,,n is a chip shifted version of the sequence c long,,n. c long,,n and c long,,n are Gold codes. 56

57 Uplink Long Scrambling Codes For code number, n n=[n 3 n ], with n being the LSB Let x n (i)andy(i) denote the i -th chip of the sequence x n and y. Initial conditions x n ()=n, x n ()=n,, x n ()=n, x n (3)=n 3, x n (4)= y()=y()= =y(3)= y(4)= 57

58 58 Uplink Long Scrambling Codes Recursive formulation, i=,, 5-7 x n (i+5) =x n (i+3) + x n (i) modulo y(i+5) = y(i+3)+y(i+) +y(i+)+y(i) modulo Gold sequence z n z n (i ) = x n (i ) + y (i ) modulo, i =,,,, 5 - Z n ( i) + if zn( i) = = for i =,,, if zn( i) = 5.

59 59 Uplink Long Scrambling Codes c long,,n (i ) = Z n (i ), i =,,,, 5 - c long,,n is a chip shifted version of the sequence c long,,n c long,,n (i ) = Z n ((i ) modulo ( 5 )), i =,,,, 5 - C i i i) = c long,, n( i) + j( ) clong, n( ) long, n(,

60 Uplink Short Scrambling Sequence Generator for 55 Chip Sequence d(i) mod mod n addition multiplication mod b(i) mod 4 + z n (i) Mapper c short,,n (i) c short,,n (i) a(i) mod

61 Uplink Short Scrambling Codes Two elementary codes: c short,,n and c short,,n 56 chips Generation From the family of periodically extended S() codes The n:th quaternary S() sequence z n (i ), n 67775, is obtained by modulo 4 addition of three sequences One quaternary sequence a (i ) Two binary sequences b (i ) and d (i ) 6

62 6 Uplink Short Scrambling Codes z n (i ) = a(i ) + b(i ) + d (i ) modulo 4 (i =.. 54) Given a code number n =[n 3 n n ] quaternary sequence a (i ): g (x)= x 8 +x 5 +3x 3 +x +x+ Initial conditions a () = n + modulo 4 a (i) = n i modulo 4, i =,,, 7, Recursive formulation a (i) = 3a (i-3) + a (i-5) + 3a (i-6) + a (i-7) + 3a (i-8) modulo 4, i = 8, 9,, 54

63 63 Uplink Short Scrambling Codes Binary sequence b(i): g (x)= x 8 +x 7 +x 5 +x+ Initial conditions B (i ) = n 8+i modulo, i =,,, 7, Recursive formulation b (i) = b (i-) + b (i-3) + b (i-7) + b (i-8) modulo, i = 8, 9,, 54

64 64 Uplink Short Scrambling Codes Binary sequence d (i ): g (x)= x 8 +x 7 +x 5 +x 4 + Initial conditions d (i ) = n 6+i modulo, i =,,, 7 Recursive formulation d (i ) = d (i-) + d (i-3) + d (i-4) + d (i-8) modulo, i = 8, 9,, 54 z n (i) = a (i) + b (i) + d (i) modulo 4 (i =.. 54)

65 65 Uplink Short Scrambling Codes z n (i) is extended to length 56 chips z n (55) = z n () Mapping C short, n is C short, n z n (i) c short,,n (i) c short,,n (i) i ( i) = cshort,, n( i mod56) + j( ) cshort,, n i mod56

66 Uplink Modulation The modulation chip rate is 3.84 Mcps. The complex-valued chip sequence generated by the spreading process is QPSK modulated. cos(ωt) Complex-valued chip sequence from spreading operations S Split real & imag. parts Re{S} Im{S} Pulseshaping Pulseshaping -sin(ωt) 66

67 Uplink Transmitter Functional Block C I DPDCH D I D Q DPCCH C ch C 56, Gain Control Antipodal Conv. >+, >- C Q Antipodal Conv. >+, > Pulse Shaping Filter Root Nyquist, r=. Pulse Shaping Filter Root Nyquist, r=. Acosω c t + + Asinω c t S T Channel Model -Complex Gaussian -Multipath Rayleigh -UMTS Channel S T C I 67

68 WCDMA Downlink Physical Layer ( 3GPP TS 5. & 5.3 ) 68

69 Table of Contents Introduction Dedicated Downlink Physical Channels Downlink Dedicated Physical Channel (DL DPCH) Common Downlink Physical Channels Common Pilot Channel (CPICH) Timing Relationship Spreading Modulation 69

70 7 Introduction CCPCH, PICH Downlink DPCH AICH, CPICH Idle MS On-line MS SCH Power-on MS

71 Downlink Transmit Diversity Open loop transmit diversity: STTD and TSTD Closed loop transmit diversity BS Physical channel type Open loop mode Closed loop TSTD STTD Mode P-CCPCH SCH S-CCPCH DPCH PICH PDSCH AICH CSICH AP-AICH - - CD/CA-ICH - - DL-DPCCH for CPCH - 7

72 Space Time Block Coding Based Transmit Antenna Diversity (STTD) The STTD encoding is optional in UTRAN. STTD support is mandatory at the UE. STTD encoding is applied on blocks of 4 consecutive channel bits. b b b b 3 Antenna b b b b 3 Channel bits -b b 3 b -b Antenna 7 STTD encoded channel bits for antenna and antenna.

73 Time Switched Transmit Diversity for SCH (TSTD) 73 TSTD can be applied to TSTD. TSTD for the SCH is optional in UTRAN, while TSTD support is mandatory in the UE. Primary SCH Secondary SCH ac p ac s i, 56 chips Slot # Slot # Slot #4 56 chips ac p ac s i, ac s i,4 One ms SCH radio frame Slot # Slot # Slot # Slot #4 ac p Antenna ac p (Tx OFF) ac p ac p ac s i, (Tx OFF) ac s i, ac s i,4 Antenna (Tx OFF) ac p (Tx OFF) (Tx OFF) (Tx OFF) ac s i, (Tx OFF) (Tx OFF)

74 74 Closed Loop Mode Transmit Diversity Spread/scramble w CPICH Ant DPCCH DPDCH DPCH Ant w CPICH w w Weight Generation 3GPP TS 5.4 V3.9. Sect. 7 Determine FBI message from Uplink DPCCH

75 Closed Loop Mode Transmit Diversity The spread complex valued signal is fed to both TX antenna branches, and weighted with antenna specific weight factors w and w, where w i = a i + jb i. The weight factors (phase adjustments in closed loop mode and phase/amplitude adjustments in closed loop mode ) are determined by the UE, and signalled to the UTRAN access point (=cell transceiver) using the D sub-field of the FBI field of uplink DPCCH. For the closed loop mode different (orthogonal) dedicated pilot symbols in the DPCCH are sent on the different antennas. For closed loop mode the same dedicated pilot symbols in the DPCCH are sent on both antennas. 75

76 Number of Feedback Information in Closed Loop Transmit Diversity 76 Summary of number of feedback information bits per slot, N FBD, feedback command length in slots, N W, feedback command rate, feedback bit rate, number of phase bits, N ph, per signalling word, number of amplitude bits, N po, per signalling word and amount of constellation rotation at UE for the two closed loop modes. Closed loop mode N FBD N W Update rate Feedback bit rate N po N ph Constellation rotation 5 Hz 5 bps π/ 4 5 Hz 5 bps 3 N/A

77 Determination of Feedback Information in Closed Loop Mode Transmit Diversity The UE uses the CPICH to separately estimate the channels seen from each antenna. Once every slot, the UE computes the phase adjustment, φ, and for mode the amplitude adjustment that should be applied at the UTRAN access point to maximise the UE received power. The UE feeds back to the UTRAN access point the information on which phase/power settings to use. Feedback Signalling Message (FSM) bits are transmitted in the portion of FBI field of uplink DPCCH slot(s) assigned to closed loop mode transmit diversity, the FBI D field. Each message is of length N W = N po +N ph bits. 77

78 78 Closed Loop Mode The UE uses the CPICH transmitted both from antenna and antenna to calculate the phase adjustment to be applied at UTRAN access point to maximise the UE received power. In each slot, UE calculates the optimum phase adjustment, φ, for antenna, which is then quantized into having two possible values as follows: π, if π / < φ φr ( i) 3π / φq =, otherwise where, i =,,4,6,8,,,4 φr ( i) = π /, i =,3,5,7,9,,3 If φ Q =, a command '' is sent to UTRAN using the FSM ph field. If φ Q = π, command '' is sent to UTRAN using the FSM ph field.

79 79 Closed Loop Mode In closed loop mode there are 6 possible combinations of phase and power adjustment. FSM po Power_ant Power_ant FSM po subfield of signalling message FSM ph subfield of signalling message FSM ph Phase difference between antennas (radians) π -3π/4 -π/ -π/4 π/4 π/ 3π/4

80 Downlink Dedicated Physical Channels (DPCH) There is only one type of downlink dedicated physical channel, the Downlink Dedicated Physical Channel (DL DPCH). Within one downlink DPCH, dedicated data generated at Layer and above, i.e. the dedicated transport channel (DCH), is transmitted in time-multiplex with control information generated at Layer (known pilot bits, TPC commands, and an optional TFCI). 8

81 8 Frame Structure of DL DPCH DPDCH DPCCH DPDCH DPCCH Data N data bits TPC N TPC bits TFCI N TFCI bits T slot = 56 chips, * k bits (k=..7) Data N data bits Pilot N pilot bits Slot # Slot # Slot #i Slot #4 One radio frame, T f = ms

82 8 Parameters Each frame= 5 slots = ms Each slot= 56 chips DL DPCH Each slot= one power-control period. SF = 5/ k (e.g., SF=5, 56,...,4) Two basic types With TFCI (for several simultaneous services) Without TFCI (fixed-rate services) It is the UTRAN that determines if a TFCI should be transmitted and it is mandatory for all UEs to support the use of TFCI in the downlink.

83 83 DL DPCH Fields (table is not completed) A B A B A B A B B A N Pilot N TFCI N TPC N Data N Data Transmitted slots per radio frame N Tr DPCCH Bits/Slot DPDCH Bits/Slot Bits / Slot SF Channel Symbol Rate (ksps) Channe Bit Rate (kbps) Slot Format #i

84 84 DL DPCH Pilot Bit Patterns Slot # Symbol # N pilot = 6 (*3) N pilot = 8 (*) N pilot = 4 (*) N pilot =

85 DL DPCH Multi-Code Transmission DPDCH DPDCH Condition: Transmission Power TPC TFCI Pilot Physical Channel Total bit rate to be transmitted exceeds the maximum bit rate Transmission Power Physical Channel Multicode transmission is mapped onto several parallel downlink DPCHs using the same spreading factor. Transmission Power One Slot (56 chips) Physical Channel L 85 Layer control information is transmitted only on the first DL DPCH.

86 86 Frame Structure: Common Pilot Channel (CPICH) Pre-defined symbol sequence T slot = 56 chips, bits = symbols Slot # Slot # Slot #i Slot #4 radio frame: T f = ms

87 Common Pilot Channel The CPICH is a fixed rate (3 kbps, SF=56) downlink physical channel that carries a pre-defined bit/symbol sequence. In case transmit diversity (open or closed loop) is used on any downlink channel in the cell, the CPICH shall be transmitted from both antennas using the same channelization and scrambling code. There are two types of Common pilot channels: The Primary CPICH. The Secondary CPICH. 87

88 Transmit Diversity of CPICH Modulation pattern for Common Pilot Channel (with A = +j) Antenna A A A A A A A A A A A A A A A A A A A A A A A A Antenna -A -A A A -A -A A A -A A -A -A A A -A -A A A -A -A A A -A -A slot #4 slot # slot # Frame#i Frame Boundary Frame#i+ In case of no transmit diversity, the symbol sequence of Antenna is used. 88

89 89 The Primary CPICH The Primary Common Pilot Channel (P-CPICH) has the following characteristics: The same channelization code is always used for the P-CPICH; The P-CPICH is scrambled by the primary scrambling code; There is one and only one P-CPICH per cell; The P-CPICH is broadcast over the entire cell. The Primary CPICH is a phase reference for the following downlink channels: SCH, Primary CCPCH, AICH, PICH AP- AICH, CD/CA-ICH, CSICH, DL-DPCCH for CPCH and the S-CCPCH. By default, the Primary CPICH is also a phase reference for downlink DPCH and any associated PDSCH. The Primary CPICH is always a phase reference for a downlink physical channel using closed loop TX diversity.

90 Secondary Common Pilot Channel (S-CPICH) A Secondary Common Pilot Channel (S-CPICH) has the following characteristics: An arbitrary channelization code of SF=56 is used for the S-CPICH; A S-CPICH is scrambled by either the primary or a secondary scrambling code; There may be zero, one, or several S-CPICHs per cell; A S-CPICH may be transmitted over the entire cell or only over a part of the cell; A Secondary CPICH may be a phase reference for a downlink DPCH. The Secondary CPICH can be a phase reference for a downlink physical channel using open loop TX diversity, instead of the Primary CPICH being a phase reference. 9

91 Downlink Phase Reference Physical Channel Type Primary-CPICH Secondary-CPICH Dedicated Pilot P-CCPCH SCH S-CCPCH DPCH PICH PDSCH* AICH CSICH DL-DPCCH for CPCH Note *: the same phase reference as with the associated DPCH shall be used. 9

92 Timing Relationship between Physical Channels Primary SCH Secondary SCH Any CPICH P-CCPCH Radio frame with (SFN modulo ) = Radio frame with (SFN modulo ) = k:th S-CCPCH τ S-CCPCH,k τ PICH PICH for k:th S-CCPCH AICH access slots # # # #3 #4 #5 #6 #7 #8 #9 # # # #3 #4 Any PDSCH n:th DPCH τ DPCH,n ms 9 ms

93 Spreading for All Downlink Physical Channels Except Synchronization Channel (SCH) I Any downlink physical channel except SCH S C ch,sf,m I+jQ S dl,n S P Q j 93

94 94 Spreading and Modulation for SCH and P- CCPCH Different downlink Physical channels (point S in Figure of previous page.) G G Σ P-SCH Σ G P S-SCH G S

95 95 Downlink Scrambling Codes 89 codes are chosen from a total of 8 - scrambling codes, numbered,,64 These chosen scrambling codes are divided into 5 sets, each set has One primary scrambling code Code number, n=6*i (i= 5) 5 secondary scrambling codes Code number, n=6*i+k (k= 5)

96 Downlink Scrambling Codes 5 primary scrambling codes Further divided into 64 scrambling code groups Each group consisting of 8 primary scrambling codes The j:th scrambling code group consists of primary scrambling codes 6*8*j+6*k (j=..63 & k=..7) Each cell is allocated one and only one primary scrambling code. The primary CCPCH, primary CPICH, PICH, AICH, AP- AICH, CD/CA-ICH, CSICH and S-CCPCH carrying PCH are always transmitted using the primary scrambling code. The other downlink physical channels can be transmitted with either the primary scrambling code or a secondary scrambling code from the set associated with the primary scrambling code of the cell. 96

97 97 Configuration of Downlink Scrambling Code Generator I Q

98 98 Downlink Scrambling Codes Constructed by combining two real sequences Each is constructed as the position wise modulo sum of two binary m-sequences, x and y Generator polynomials is of degree chip segments ( ms radio frame) Gold sequences x sequence: generator polynomial +X 7 +X 8 Initial: x ()=, x()= x()=...= x (6)= x (7)= x(i+8) =x(i+7) + x(i) modulo, i=,, 8 -, y sequence: generator polynomial +y 5 +y 7 + y +y 8 Initial: y()=y()= =y(6)= y(7)= y(i+8) = y(i+)+y(i+7)+y(i+5)+y(i) modulo, i=,, 8 -

99 99 Downlink Scrambling Codes The nth Gold code sequence z n is z n (i) = x((i+n) modulo ( 8 - )) + y(i) modulo, i=,, 8 - Mapping Z n ( i) + if z n ( i) = = for i =,,, if z n ( i) = 8 The n:th complex scrambling code sequence S dl,n is defined as: S dl,n (i) = Z n (i) + j Z n ((i+37) modulo ( 8 -)), i=,,,

100 Downlink Modulation In the downlink, the complex-valued chip sequence generated by the spreading process is QPSK modulated: cos(ωt) Complex-valued chip sequence from summing operations T Split real & imag. parts Re{T} Im{T} Pulseshaping Pulseshaping -sin(ωt)

101 Downlink Transmitter Functional Block C I C ch Gain Control DPDCH/ DPCCH D I D Q C ch j + Antipodal Conv. >+, >- C Q + Antipodal Conv. >+, >- + Other User Signals Pulse Shaping Filter Root Nyquist, r=. Pulse Shaping Filter Root Nyquist, r=. + + S T Channel Model -Complex Gaussian -Multipath Rayleigh -UMTS Channel S T C I