1. Outline of ISDB-T Transmission System Interval Adding 1.1 Features of ISDB-T and Technical 4.2 Quadrature Modulation Baseline

ISDB-T technical seminar(2007) in Brazil Preface

Transmission system of ISDB-T is most feature of ISDB-T. Different from Section 3 another DTTB standard, ATSC and DVB-T. For examples, (1)One segment service within same bandwidth, (2)High Transmission system performances for mobile/portable reception, (3)Robustness against multi- path and impulse noise, etc. These features re mainly led from ISDB-T June, 2007 transmission system. Digital Broadcasting Expert Group (DiBEG) So, it is very important to study the structure of ISDB-T transmission system for understanding the background of the features of ISDB-T. Japan This seminar document is prepared according ARIB STD-B31. But ,as Yasuo TAKAHASHI described in seminar #2, SBTVD-T 01 is almost same as B31. Therefore, it is useful for Brazilian engineer to know this section. (Toshiba)

In this section, mainly the principle of channel coding and OFDM Modulation technology are presented.

1 2 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

Contents

1. Outline of ISDB-T transmission 4. OFDM modulation system 4.1 OFDM modulation and Guard 1. Outline of ISDB-T transmission system interval adding 1.1 Features of ISDB-T and technical 4.2 Quadrature modulation baseline

1.2 Block diagrams of transmission 5. Outline of ISDB-TSB system 5.1 outline of ISDB-TSB transmission system 1.3 transmission parameter 1.1 Features of ISDB-T and technical baseline 5.2 Consecutive transmission system 2. Principle of segment construction and hierarchical transmission 5.3 example of consecutive transmission station 1.2 Block diagrams of transmission system 3. Transmission coding 3.1 Channel coding 1.3 transmission parameter 3.2 Mapping and Interleaving

3 4 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group Requirement for transmission system →Solutions Features of ISDB-T transmission system

High-Quality, -HDTV 1CH or SDTV 3CH within 6MHz band. Multi-Channels -Robustness against multi-path

Multimedia-Service Japanese Requirements for DTTB -Integrated Service(Video/Audio/Data) Technical Specification

-High quality Data Service Flexible/Versatile OFDM Robustness, SFN -Bi-directional Service

Efficient Spectrum Segment Structure Extensible, Partial Reception Single Frequency Network(SFN) utilization

Time Interleaving Mobile Reception, Indoor Reception Mobile and handheld -Robustness against mobile/portable reception service -fixed/mobile/portable service within same band --- Layer Transmission Technology TMCC Flexible, Versatile

Commonality of - Commonality for BS/Cable/Terrestrial receiver Broadcasting. 5 6 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

ISDB-T system Segmented Structure and Partial Reception

Band Segmented OFDM : Orthogonal Frequency Division (Example; 1seg + 12 seg) Multiplexing Layer A Layer B (LDTV,Audio,Data) Features (HDTV or Multi- 6MHz SDTV with Data)) • Modulation: DQPSK, 13segments 13 Segments QPSK, 16QAM, 64QAM (6MHz bandwidth) frequency 1 segment 429KHz • 1HDTV or N SDTV/channel

• Net data rate: 23.42Mbps (6MHz) QPSK constellation Difference of required C/N 64QAM constellation • Single Frequency Network Between 64QAM and QPSK is about 12 dB • Mobile reception *13 segments are divided into layers, maximum number of layers is 3. (time interleaving) Frequency *Any number of segment for each layers can be selected (totally 13 segment) *Transmission parameter sets of each layer can be set independently (In above example, modulation index of each layer are different) 7 8 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group Feature of ISDB-T transmission system

Byte -> Bits Energy Delay Bits -> Byte Byte Byte -> Bits Convolutional dispersal adjust- interleaving coding 1. Efficient frequency utilization MSB first ment MSB first MSB first (1)Adopt OFDM transmission system; SFN operation TS Outer Division MPEG-2 TS Energy Delay Byte Convolutional code of TS into Byte -> Bits Bits -> Byte Byte -> Bits (2)Adopt hierarchical transmission; service for different type of reception in one adjust- coding multiplexer re-multiple (204,188) hierarchi- MSB first dispersal ment MSB first interleaving MSB first frequency channel xer cal levels

Byte -> Bits Energy Delay Bits -> Byte Byte Byte -> Bits Convolutional 2. Mobile/ handheld service in one transmission standard adjust- coding MSB first dispersal ment MSB first interleaving MSB first (1)Time interleave; Improve mobile reception quality Carrier modulation (2)Partial reception; handheld service in same channel Bit interleaving Mapping

Carrier modulation 3. Robustness against interference Guard- Bit interleaving Mapping IFFT interval levels frame structure (1) Adopt concatenated error correction with plural interleave - addition

(2)Time interleave; very effective for impulse noise (urban noise) Carrier modulation Time interleaving OFDM Bit interleaving Mapping Frequency interleaving Combining of hierarchical 4. Flexibility for several type of service/ reception style 5. Commonality of TV/audio transmission standard Pilot signals 6. Auxiliary (AC) channel can be used for transmission network TMCC signal management Transmission system blockdiagram( B31 Fig.3-2) 9 10 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

Equation for calculating bit rate Parameters of ISDB-T (6MHz Bandwidth) STEP 1: calculate the bit rate of one(1) segment ISDB-T is composed 13 segments, so, to calculate transmission bit rate, ISDB-T mode Mode 1 (2k) Mode 2 (4k) Mode 3 (8k) at first, calculate the bit rate of one(1) segment, and multiply number of Segment of each layer. Then lead total bit rate of each layer Number of OFDM segment 13 (1) reed-Solomon coding rate; (188/204), fixed value Useful bandwidth 5.575MHz 5.573MHz 5.572MHz (2) r: convolutional coding rate( depends on coding rate) Carrier spacing 3.968kHz 1.984kHz 0.992kHz (3) M: modulation index(bit/ symbol); QPSK=2, 16QAM=4 , 64QAM=6 Total carriers 1405 2809 4992 (4) Ts/(Ts+Tg); ratio of total symbol length and effective symbol length Modulation QPSK , 16QAM , 64QAM , DQPSK (5) (effective data carrier)/(total carrier) =96/108 – fixed value for mode 1, 2, 3 Number of symbols / frame 204 (note) total carrier; including pilot carrier, TMCC, and scattered pilot symbol Active symbol duration 252μ ss504μ 1.008ms (6)Nf : Number of carrier in one segment; mode 1=108,mode 2=216, mode 3=432 Guard interval duration 1/4 , 1/8 , 1/16 , 1/32 of active symbol duration (7) fd: carrier spacing = effective symbol transmission speed Inner code Convolutional code (1/2 , 2/3 , 3/4 , 5/6 , 7/8) mode 1=(6/14)/108*103 kHz=3.9682540kHz, mode 2= (1/2) of mode 1 Outer code RS (204,188) mode 3=(1/4) of mode 1 Time interleave 0 ～ 0.5s (note) (6/14)*103 kHz = bandwidth of one(1) segment Useful bit rate 3.651Mbps ～ 23.234Mbps 11 12 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group Example Mode 3, guard interval ratio=1/16, modulation=QPSK, coding rate(r)=2/3

Bit rate of 1 segment=0.9920635 *432 * (16/17) * 2 * (2/3) * (188/204) =440.56 kbps 2. Segment construction and Hierarchical Transmission fd Nf Ts/(Ts+Tg) Mr RS coding rate

STEP 2 : multiply number of segment (Nseg)

Example 1 : 1 layer fixed reception, mode 3, guard interval ratio=1/16, Modulation =64QAM, coding rate(r)=3/4 Number of segment 2.1 Concept and feature of hierarchical transmission system

Bit rate of 1 segment=0.9920635 *432 * (16/17) * 6 * (3/4) * (188/204) * 13 =19.329 Mbps 2.2 The rules of hierarchical transmission

Example 2 : 2 layer ,1 segment for portable, 12 segment for fixed 2.3 Segment construction and hierarchical transmission Layer A: Nseg=1, mode 3, Tg/Ts=1/16, M=2(QPSK), r=2/3 Bit rate of A layer=0.9920635 *432 * (16/17) * 2 * (2/3) * (188/204) * 1 =440.56 kbps Relating clause of ARIB standard; B31 clause 3.2 Layer B: Nseg=12, mode 3, Tg/Ts=1/16, M=6(64QAM), r=3/4 Bit rate of A layer=0.9920635 *432 * (16/17) * 6 * (3/4) * (188/204) * 12 =17.842 Mbps

13 14 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

Blockdiagram of ISDB-T Transmission coding 2.1 Concept and feature of hierarchical transmission system

TS Hierarchical transmission is the feature of ISDB-T, this concept is not in DVB-T TS RS Divide Energy Delay Byte Convolutional system. The concept of hierarchical transmission system is shown in figure.2-1after. RE-MUX Coding To Dispersal Adjust Interleave Coding Hierarchy The transmission parameters can be assigned as each service ID. This transmission system is called “hierarchical transmission” For example, the service which should be strong against interference such as noise should be assigned to QPSK layer, other service is assigned to 64QAM layer. In this case, service of QPSK layer could be received under serious receiving Bit Combine Frequency Time OFDM Mapping Interleave Hierarchy Interleave Interleave Framing condition such as handheld reception. In case of DVB-T system, for handheld reception service, another frequency should Pilot/TMCC/AC be prepared separately. But, in ISDB-T system, different reception service can be achieved within one frequency channel by making use of this transmission system.,

OFDM signal Add Quad. D/A TSP’s are divided into plural layers at Re-multiplexer, and re-arranged in each layer. IFFT Guard interval MOD Conv. After re-arranged, these TSP’s are combined to 1 transport stream and feed to OFDM modulator. (see figure. 2-2)

These functions are presented in this section 15 16 DiBEG DiBEG -16- Digital Broadcasting Experts Group Digital Broadcasting Experts Group Fig.2-1 Image of hierarchical transmission

Transmission capacity is not Fig. 2-2 Blockdiagram of TS re-multiplexer high, but interference level is low Combine each hierarchy, and re-arrange TSP’s Divide TSP’s into TS input PID A layer A layer each hierarchy buffer extract buffer MUX

B layer B layer Path of QPSK layer DE- buffer

buffer MUX MUX MUX TS re-multiplex output C layer C layer Path of 64 QAM layer buffer buffer INF１ MUX

TS input PCR ２ INF select TS input INF３ PSI-SI buffer Packet which path through the QPSK layer TS input INF４ Transmission capacity is high, but Packet which path through the 64 QAM layer interference level is high

Interference such as noise 17 18 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

Fig. 2-3 Image of multiple layer transmission 2.2 The rules of hierarchical transmission Example of 2 programs into 3 layers (a) The strongest hierarchy layer should be able to be demodulated and decoded alone . TV Reason; to be able to demodulate and decode, PCR and minimum required PSI program #1-V #1-A #2-A MUX should be transmitted by strongest layer. (see Fig.2-4) #1 Layer A #1-A (b) Transmission delay difference between hierarchy should be compensated at the transmission side. The compensated transport stream is called “Multi-frame pattern” #1-D ISDB-T M Image of Multi-frame pattern is shown in Fig. 2-5 later Re multi- #1-D #2-D U X (c) Multi-frame pattern should be completed within 1 OFDM frame. #2-V plexer Layer B TV program #2-A (d) The number of packet in 1 segment should be integer in any combination of transmission parameter and coding rate. #2 #1-V #2-V #2-D Reason; minimum unit of hierarchical transmission is the segment. Layer C (e) Even though the information transmission speed is different because of its transmission parameters, the clock rate of TS at the output of receiver RS decoder should be constant( for TV, clock rate is 4fs). To adjust the clock rate, Null packets are inserted. See details in fig. 2-6 later.

19 20 DiBEG DiBEG -20- Digital Broadcasting Experts Group Digital Broadcasting Experts Group Fig. 2-5 Concept of hierarchical transmission(1/2) Fig. 2-4 Concept of hierarchical transmission (delay adjustment of each layers) Time axis (strongest layer should be recovered alone) Transmit TS A-1 B-1 B-2 A-2 B-3 B-4 A-3 B-5 B-6 A-4 B-7 Transmit A-1 B-1 B-2 A-2 B-3 B-4 A-3 B-5 B-6 A-4 B-7 TSP（RS Transmission in A-1 A-2 A-3 A-4 input） layer A The B layer packets are Received layer A-1 A-2 A-3 interfered and broken A TS Received TSP Transmission in （RS output） A-1 B-1 B-2 A-2 B-3 B-4 A-3 B-5 B-6 A-4 B-7 layer B B-1 B-2 B-3 B-4 B-5 B-6 B-7

Recovered TSP’s Received layer B TS B-1 B-2 B-3 B-4 B-5 B-6

Layer A + layer B(order is A-1 …………A-2 A-3 A-4 different from transmission side B-1 A-1 B-2 B-3 A-2 B-4 B-5 A-3 B-6 (operation of S1 in Fig.2-7) As shown above, Transmission delay of each layer is different according TSP’s of layer A should include PCR and minimum to each layer transmission parameter set. As a result, because of its required PSI which are necessary to recover TSP transmission parameter set. Therefore, order of TSPof receiver side is 21 different from transmitter side 22 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

Fig. 2-5 Concept of hierarchical transmission(2/2) Fig. 2-6 Concept of hierarchical transmission (delay adjustment of each layers) Time axis (How to adjust constant clock rate)

Transmit TS A-1 B-1 B-2 A-2 B-3 B-4 A-3 B-5 B-6 A-4 B-7 Transmit TS A-1 null null A-2 null null A-3 null null A-4 null null (RS coder input) Transmission in A-1 A-2 A-3 A-4 layer A Null packets are not Received layer transmitted A-1 A-2 A-3 A TS Transmission in transmission A-1 A-2 A-3 A-4 layer B B-1 B-2 B-3 B-4 B-5 B-6

Received layer Delay B TS B-1 B-2 B-3 B-4 B-5 B-6 adjustment Received TS A-1 null null A-2 null null A-3 null null Layer A + layer (RS decoder output) A-1 B-1 B-2 A-2 B-3 B-4 A-3 B-5 B-6 (operation of S1 in Fig.2-7) Packet output timing (operation of S2 in Fig.2-7) As shown above, delay adjustment is inserted at transmitter side. At the output portion of receiver RS decoder, TS is read by same clock rate of As a result, same order of TSP is recovered in receiver side. transmit TS (for TV, clock rate is 4fs). At the timing of head packet, packet does Not decoded yet, in this case, RS decoder feeds null packet. If decoded, RS decoder 23 feeds decoded packet. 24 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group Figure 2-7 Model receiver for multi-frame reproducing 2.3 Segment construction and hierarchical transmission Differential demodulation Frequency/time FFT Synchronous de-interleaving Segment of ISDB-T is the concept for hierarchical transmission. The segment is demodulation TS decided as follows considering the rule shown in clause 2.2 reproduction section S3 Hierarchical S2 (1) Number of TSP in one OFDM frame is integer for all cases of transmission level A TS buffer S4 S1 TS parameter set. Number of TSP is shown in Table 2-1. De- Hierarchical puncturing buffer

Null TSP reproduction Viterbi (2) For easy tuning operation of receiver, bandwidth of 1 segment is set to 6/14 Hierarchical decoding level C S2 MHz. Division into Division De- Hierarchical Combining of TS buffer hierarchical levels hierarchical levels puncturing buffer TS (3) Number of multi-frame pattern is proportional to number of set of hierarchy.

Null TSP reproduction For this reason, number of hierarchy is limited as many as 3.

S1; select the layer. If all data of 1 packet has been input to buffer, S1 select the buffer and send data to next stage

S2; select TS/Null packet, according to TS buffer status

25 26 DiBEG DiBEG -26- Digital Broadcasting Experts Group Digital Broadcasting Experts Group

Table 2-1 Number of TSP in one OFDM frame

(mode 1) 3. Channel coding coding rate 1/2 2/3 3/4 5/6 7/8 modulation DQPSK／QPSK 12 16 18 20 21 16QAM 24 32 36 40 42 64QAM 36 48 54 60 63

(note1) number of TSP/segment (note 2) in case of mode 2 , number of TSP is twice , and in case of mode 3, four times Relating clause of ARIB standard; B31 clause 3.3 – clause 3.11

27 28 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group Blockdiagram of ISDB-T Transmission coding Outer coder (Reed-Solomon coding)

A shortened Reed-Solomon code (204,188) is used in every TSP as an outer code. The TS shortened Reed-Solomon (204,188) code is generated by adding 51-byte 00HEX at the TS RS Divide Energy Delay Byte Convolutional beginning of the input of the data bytes of Reed-Solomon (255,239) code, and then To RE-MUX Coding Dispersal Adjust Interleave Coding removing these 51 bytes. Hierarchy The GF (28) element is used as the Reed-Solomon code element. The following primitive polynomial p (x) is used to define GF (28): p (x) = x8 + x4 + x3 + x2 + 1 Note also that the following polynomial g (x) is used to generate (204,188) shortened Reed-Solomon code: g (x) = (x - λ0) (x - λ1) (x - λ2) ---- (x - λ15) provided that λ = 02 HEX Bit Combine Frequency Time OFDM Mapping Interleave Hierarchy Interleave Interleave Framing Sync. Data (a) MPEG-2 TSP 1 byte Pilot/TMCC/AC (187 bytes)

Sync. Data Parity 1 byte (187 bytes) 16 byte OFDM signal Add Quad. D/A IFFT Guard interval MOD Conv. (b) TSP error-protected by RS code (transmission TSP)

MPEG2 TSP and Transmission TSP(B31, Fig. 3-6) These functions are presented in this section 29 30 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

Inner coding

Energy Dispersal G = 171 Octal 1 Output X Energy dispersal is conducted at each hierarchical layer using a circuit, shown in Fig. 3-8, that is generated by a PRBS (Pseudo Random Bit Sequence). All signals other than the Data input synchronization byte in each of the transmission TSPs at different hierarchical layers are D D D D D D EXCLUSIVE ORed using PRBSs, on a bit-by-bit basis.

g(x) = X15 + X14 + 1 Output Y G 2 = 133 Octal

+ Fig. 3-10: Coding Circuit of a Convolutional Code with Constraint Length k of 7 and a Coding Rate of 1/2 D D D D D D D D D D D D D D D Coding rate Puncturing pattern Transmission-signal sequence

123456789101112131415 X : 1 1/2 X1, Y1 Y : 1 X : 1 0 output 2/3 X1, Y1, Y2 Y : 1 1 X : 1 0 1 3/4 X1, Y1, Y2, X3 Y : 1 1 0 PRBS-Generating Polynomial and Circuit (B31,Fig. 3-8) X : 1 0 1 0 1 5/6 X1, Y1, Y2, X3 Y4, X5 Y : 1 1 0 1 0 X : 1 0 0 0 1 0 1 7/8 Y : 1 1 1 1 0 1 0 X1, Y1, Y2, Y3, Y4, X5, Y6, X7

31 Table 3-8: Inner-Code Coding Rates and Transmission-Signal Sequence 32 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group Puncturing Pattern Example of input C/N vs BER characteristics

Mode;1 GI=1/8, 64QAM, I=0, RS;OFF Convolutional X out(1 bit) data input(1 bit) output（x bits） 1.00E+00 Coding Puncture (K=7) Y out(1 bit) 1.00E-01

coding Number of Number of Puncturing Output of no correction rate input bits output bits pattern puncturing 1.00E-02 1/2 1 2 X:1 X1, Y1 FEC=7/8 FEC= Y:1 (2) 1.00E-03 FEC= BER FEC= 2/3 2 4 X: 10 X1, Y1, Y2 FEC=5/6 FEC= Y: 11 (3) 1.00E-04 3/4 3 6 X: 101 X1, Y1, Y2 ,Y3 FEC=3/4 Y: 110 (4)

1.00E-05 5/6 5 10 X: 10101 X1, Y1, Y2 ,Y3 ,Y4, Y5 Y: 11010 (6) 7/8 7 14 X: 1000101 X1, Y1, Y2 ,Y3 ,Y4, Y5,Y6,Y7 1.00E-06 0 5 10 15 20 25 30 35 40 Y: 1111010 (8) 33 C/N[dB] 34 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

Effect of interleave Kind of interleave and these effect

Interleave is one of important technology in transmission system. Error correction system is most effective when the characteristics of noise is random. Convolu- RS Byte Bit Time Frequency The purpose of interleave is to randomize the burst error occurred in transmission path tional Mapping coder interleaveﾞ interleaveﾞ interleaveﾞ interleave coding Burst error; FEC does not work well Random error; FEC works well Byte interleave ×××× × × × × Byte interleave is located between outer coder and inner coder. Randomize the burst error of Viterbi decoder output

Bit interleave Bit interleave is located between convolutional coding and mapping. Randomize the symbol error before Viterbi decoding transmitter before interleave transmitter after interleave Burst error occurs at Time interleave interleave transmission path Time interleave is located at the output of maping(modulation). And randomize the burst error of time domain which is mainly caused by impulse noise, fading of mobile reception, etc. ×××× × × × × Frequency interleave receiver after de-interleave receiver before de-interleave Frequency interleave is located at the output of time interleave. Randomize the burst error of de-interleave frequency domain which is mainly caused by multi-path , carrier interference, etc. 35 36 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group Bit interleave Byte interleave (B31, clause 3.9.3)

The 204-byte transmission TSP, which is error-protected by means of RS code and Bit interleave circuit is different according to carrier modulation. Following diagram is energy-dispersed, undergoes convolutional byte interleaving. Interleaving must be 12 a example of 16QAM. bytes in depth. Note, however, that the byte next to the synchronization byte must b*0 pass through a reference path that causes no delay. b*1 16QAM I b0,b1,b2,b3,b11・・ 40 bits delay S/ Mapping b*2 80bits delay 0 P Q b*3 120 bits delay 1 17 bytes 2 17×2 bytes bC0 b80 b40 b00 b00 bX0 bY0 bZ0 3 bC1 b81 b41 b01 b41 b01 bX1 bY1 17×3 bytes bC2 b82 b42 b02 b82 b42 b02 bX2 Switching between paths every byte bC3 b83 b43 b03 bC3 b83 b43 b03

11 17×3 bytes FIFO shift register ４０ carriers ４０ carriers Without bit interleave; With bit interleave; 37 burst error errors are randomized 38 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

Relation between OFDM frame and interleave Effect of time interleave

no time interleave With time interleave time Transmitting frequency Receiving delay delay 203N 203N 203N 203N 203N 203N +1 +2 +3 +4 +5 +N Transmitter

Time interleave side time time

field strength varied

Error symbol N+1 N+2 N+3 N+4 N+5 2N receiver side 1 2 3 4 5 N frequency (After de-interleave) N=1404(mode 1) 2808(mode 2) Frequency interleave 5616(mode 3) Burst error Error randomized 39 40 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group 3-2. What is the merit of Time- Interleave? (2/2) •How much improved by using Time- Interleave 0 Intradata-segment time 0 Following graph shows degradation by impulse noise, which is dedicated by 1 interleaving section 1 Mackenzie Presbyterian University measured in Autumn , 2005 2 No. 0 2 0 50 100 150 200 250 300 350 400 450 500 : : 16 nc -1 c-1 14 n 0 Intradata-segment time 0 12 DVB-T interleaving section : 10 n -1 No. 1 -1 8 (7dB improved!) c c Switched Switched 6 0 Intradata-segment time 0 every IFFT every IFFT interleaving section : 4 sample clock sample clock 2 nc -1 No. 2 c-1 0 ISDB-T -2 ATSC 0 Intradata-segment time 0 -4 interleaving section : : -6 nc -1 No. 12 c-1 -8 C/Neq [dB] (Carrie to Equivalent Gaussia Equivalent to (Carrie [dB] C/Neq -10

-12 Time interleaver blockdiagram(B31, 3.11.1) Pulse Width [µs] ATSC Latest Generation - 19.39Mbps-8 VSB 2/3 ATSC Previous Generation - 19.39Mbps-8 VSB 2/3 DVB Latest Generation - 19.3Mbps-64QAM 8k 3/4 1/16 DVB Previous Generation - 19.3Mbps-64QAM 8k 3/4 1/16 ISDB Latest Generation - 19.3Mbps - 64QAM 8k 3/4 1/16 0,2s ISDB Previous Generation - 19.3Mbps - 64QAM 8k 3/4 1/16 0,2s

7dB improved Transmitter power reduced to 1/5 !! 41 42 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

Table 3-12: Time Interleaving Lengths and Delay Adjustment Values

0 Ixm0 symbol buffer Mode 1 Mode 2 Mode 3 Numbe Numbe Numbe 1 Number Number Number r of r of r of Ixm1 symbol buffer of delayed of delayed of delayed Provided that mi = (i × 5) mod 96 delay- delay- delay- Length frames in Length frames in Length frames in adjust adjust adjust 2 (I) transmiss (I) transmiss (I) transmiss Ixm2 symbol buffer ment ment ment ion and ion and ion and symbol symbol symbol reception reception reception s s s nc-1 nc is 96, 192, and 384 Ixm symbol buffer in modes 1, 2, and 3, respectively. 0 0 0 0 0 0 0 0 0 nc-1 4 28 2 2 14 1 1 109 1 8 56 4 4 28 2 2 14 1 16 112 8 8 56 4 4 28 2 Fig. 3-23: Configuration of the Intra-segment Time Interleaving Section (Notification)

43 44 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group Effect of frequency interleave Frequency characteristics distortion caused by multi-path Frequency This drawing shows the effect of multi-path. As shown, received interleave signal level is varied in frequency domain.

Envelope of Reciprocal of combined wave delay time Multi-path

x x Multi- x x x x x x x x x path

Direct path In-band Frequency Received frequency de-interleave x ; error Vector diagram signal Frequency characteristics

As shown above, function of frequency interleave is to disperse the error caused by multi-path 45 46 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

The input signal must be 2 bits per symbol and QPSK-mapped to output multi-bit I- and Q-axes data. To conduct mapping, the 120-bit delay element shown in Fig. 3-14 is inserted into the mapping input for bit interleaving. Figs. 3-14 and 3-15 show the system diagram and mapping constellation,

respectively. T

b0 Partial-reception portion Intrasegment carrier Intrasegment carrier I rotation randomizing S/P QPSK Differentially 120-bit retardation mapping b0,b1,⋅⋅⋅ element Q modulated portion b1 OFDM- Segment Intersegment Intrasegment carrier Intrasegment carrier frame 120-bit delay division interleaving rotation randomizing Fig. 3-14: QPSK Modulationelement System Diagram formation Q (level corresponding to b1) (1,0) (b0,b1)=(0,0) Intersegment Intrasegment carrier Intrasegment carrier +1 Synchronously interleaving rotation randomizing modulated portion I (level corresponding to b0) -1 +1 Configuration of frequency interleaving section (1,1) -1 (0,1)

Fig. 3-15: QPSK Constellation

Mapping . 47 48 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group The input signal must be 4 bits per symbol and 16QAM-mapped to output multi-bit I- and Q- axes data. To conduct mapping, the delay elements shown in Fig. 3-16 are inserted into b1 to b3 Required C/N (dB) (note) for bit interleaving. Figs. 3-16 and 3-17 show the system diagram and mapping constellation, respectively. t Coding rate b0

b1 40-bit retardation element 16QAM I Modulation 1/2 2/3 3/4 5/6 7/8 S/P b2 80-bit retardation mapping b0,b1,b2,b3⋅⋅⋅ element b3 Q 120-bit retardation 40-bitelement delay QPSK 4.9 6.6 7.5 8.5 9.1 element Fig. 3-16: 16QAM Modulation80-bit delay System Diagram element 120-bit delay Q (Level correspondingelement to b1, b3) DQPSK 6.2 7.7 8.7 9.6 10.4 (1,0,0,0) (1,0,1,0)( 0,0,1,0) (b0,b1,b2,b3) = (0,0,0,0) +3 16QAM 11.5 13.5 14.6 15.6 16.2 (1,0,0,1) (1,0,1,1)( 0,0,1,1) (0,0,0,1) +1 I (Level corresponding -3 -1 +1 +3 to b0, b2) 64QAM 16.5 18.7 20.1 21.3 22.0 -1 (1,1,0,1) (1,1,1,1)( 0,1,1,1) (0,1,0,1)

-3 -4 (1,1,0,0) (1,1,1,0)( 0,1,1,0) (0,1,0,0) (note) after Viterbi decoding, BER is as much as 2*10

Fig. 3-17: 16QAM Constellation Note: these data are simulation data at early stage,

Mapping . but recently, receiver LSI shows more good data. 49 50 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

Input C/N vs BER characteristics

Mode; 1, GI=1/8 FEC=3/4, RS=OFF 4. OFDM modulation 1.00E+00

1.00E-01 (1) IFFT 1.00E-02 (2) Pilot signal QPSK 1.00E-03 64QAM DQPSK (3) AC BER 16QAM 64QAM (4) TMCC 1.00E-04 １６ＱＡＭ (5) Guard interval

1.00E-05ＤＱＰＳＫ (6) Quad. Modulation and RF format

1.00E-06ＱＰＳＫ Relating clause of ARIB standard; B31 clause 3.12 – clause 3.15 0 5 10 15 20 25 30 35 40 51 52 C/N[dB] DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group Blockdiagram of ISDB-T Transmission coding Nyquist separation and orthogonal FDM

Fourier transform and inverse FFT TS TS RS Divide Energy Delay Byte Convolutional RE-MUX Coding To Dispersal Adjust Interleave Coding amplitude Hierarchy

frequency T

Bit Combine Frequency Time OFDM Mapping Interleave Hierarchy Interleave Interleave Framing Nyquist bandwidth time １／Ｔ

Pilot/TMCC/AC Orthogonal division

OFDM signal multiplex Add Quad. D/A IFFT Guard interval MOD Conv.

These functions are presented in this section At the adjacent carrier position ,all other 53 carrier energy is zero. 54 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

OFDM signal generation by IFFT IFFT output and frequency allocation

Symbol length = T f=3/T Q axis x f=2/T x x f=2/T I axis x x x f=1/T f=1/T x x x Sample point f=0

x; Sample point to generate sine wave of f=1/T cycle Symbol length=T

Sample point to generate sine wave of f=2/T cycle IFFT output

55 Freq. separation=1/T 56 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

Time axis Frequency axis TV signal spectrum carrier #1

+ + carrier #2

+ + analog Digital; OFDM +

carrier #k +

+ + =

OFDM signal

Frequency

GI Effective symbol Example of OFDM signal waveform OFDM symbol 57 58 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

OFDM frame structure (DQPSK, mode 1) OFDM frame structure (QPSK, 16QAM, 64QAM, mode 1) Carrier number Carrier number 0 1 2 107 0 1 2 3 4 5 6 7 8 9 10 11 12 107

S0,0 S1,0 S95,0 0 SP S0,0 S1,0 S2,0 S3,0 S4,0 S5,0 S6,0 S7,0 S8,0 S9,0 S10,0 SP S95,0

S0,1 S1,1 S95,1 1 S0,1 S1,1 S2,1 SP S3,1 S4,1 S5,1 S6,1 S7,1 S8,1 S9,1 S10,1 S11,1 S95,1 S S S 0,2 1,2 95,2 2 S0,2 S1,2 S2,2 S3,2 S4,2 S5,2 SP S6,2 S7,2 S9,2 S9,2 S10,2 S11,2 S95,2

S0,3 S1,3 S95,3 3 S0,3 S1,3 S2,3 S3,3 S4,3 S5,3 S5,3 S6,3 S7,3 SP S9,3 S10,3 S11,3 S95,3 4 S S S S S S S S S S S S S0,4 S1,4 S95,4 SP 0,4 2,4 2,4 3,4 4,4 5,4 6,4 7,4 8,4 9,4 10,4 SP 95,4

SP S95,5 S0,5 S1,5 S95,5

S95,6 S0,6 S1,6 S95,6 S95,7

S0,7 S1,7 S95,7 CP TMCC TMCC AC (AC1) AC (AC1, AC2) AC (AC1, OFDM-symbol number OFDM-symbol OFDM-symbol number OFDM-symbol

200 SP

201 S0,201 S1,201 S2,201 SP S3,201 S4,201 S5,201 S6,201 S7,201 S8,201 S95,201

202 S0,202 S1,202 S2,202 S3,202 S5,201 S5,202 SP S6,202 S7,202 S8,202 S95,202

203 S0,203 S1,203 S2,203 S3,203 S4,203 S5,203 S6,203 S7,203 S8,203 SP S95,203 S0,203 S1,203 S95,203 203 76 543210 59 60 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group Effect of scattered pilot (SP) signal

Frequency characteristics distortion caused by multi-path Scattered pilot (SP) is used to Compensate the frequency distortion This drawing shows the effect of multi-path. As shown, received caused by multi-path signal level is varied in frequency domain. frequency Estimation of transmission characteristics by SP Envelope of Reciprocal of combined wave delay time frequency

Multi- path

Direct path In-band Received frequency

Vector diagram signal Frequency characteristics time

TMCC Scattered pilot (SP) AC(Auxiary Channel) 61 62 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

What is AC? Example of AC, TMCC (mode 1, QPSK,16QAM, 64QAM) AC; (Auxiliary Channel) AC is a channel designed to convey additional information on modulating signal- (a) AC and TMCC Carrier Arrangements in Mode 1 transmission control. AC’s additional information is transmitted by modulating the pilot carrier of a Segment 11 9 7 5 3 1 0 2 4 6 8 10 12 No. type similar to CP through DBPSK. The reference for differential modulation is provided at the first frame symbol, and takes the signal point that corresponds to AC1_ 1 10 53 61 11 20 74 35 76 4 40 8 7 98 the Wi value stipulated in Section 3.13.1. AC1_ 2 28 83 100 101 40 100 79 97 89 89 64 89 101 Details of AC is specified in ARIB STD-B31 reference TMCC 1 70 25 17 86 44 47 49 31 83 61 85 101 23 Recently, new utilization of AC has been proposed, that is, the transmission network management information can be carried to relay station by using AC. Details will be explained in seminar #9

In DVB-T system, CP is inserted for carrier synchronization instead of AC, but CP cannot carry any information. This is the feature of AC

63 64 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group TMCC; transmission management and configuration control signal Guard interval A guard interval, the latter part of the IFFT (Inverse Fast Fourier Transform) data The TMCC signal is used to convey information on how the receiver is to perform output for the specified duration, is added without any modification to the beginning demodulation of information such as the hierarchical configuration and the OFDM- of the effective symbol. This operation is shown in Fig. 3-33. segment transmission parameters.

IFFT output data IFFT output data

Guard Guard Table 3-20: Bit Assignment Effective symbol Effective symbol t interval interval

B0 Reference for differential demodulation

B1 – B16 Synchronizing signal (w0 = 0011010111101110, w1 = 1100101000010001)

B17 – B19 Segment type identification (differential: 111;synchronous: 000) switch B – B TMCC information (102 bits) I axis 1 effective I axis 20 121 Symbol delay B122 – B203 Parity bit See details of TMCC information in 3.15.6 of ARIB STD-B31 IFFT

Q axis Q axis

65 66 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

Performances under multi-path condition Effect of guard interval Time Axis •Performances of each DTTB systems Transmitted OFDM symbol Following graph shows degradation by single multi-path, which is dedicated by Mackenzie Presbyterian University measured in Autumn , 2005

(a) GI Effective Symbol GI Effective Symbol -300 -250 -200 -150 -100 -50 0 50 100 150 200 250 300 -2

2 GI Effective Symbol GI Effective Symbol (b) 4

td 6 ISDB-T

12 FFT Window 14 (a) : Direct wave from transmitter, (b) : reflected wave (multi-path wave) 16 ATSC

Desired to Undesired (D/U) [dB] [dB] (D/U) Undesired to Desired 18

GI: Guard Interval , td: delay time of multi-path, (c) FFT window of receiver 20

24 FFT window of receiver cuts a signal with Ts (effective symbol ) length, this signal is D e la y S p re a d (µ s ) A TS C Latest G eneration - 19.39M bps - 8V S B 2/3 ATSC Previous Generation - 19.39M bps - 8VSB 2/3 fed to FFT to demodulate OFDM signal. If FFT window can be set within the interval DVB -T Latest Generation - 19.76M bps - 64QAM 8k 3/4 1/16 DVB-T Previous Generation - 19.76M bps - 64QAM 8k 3/4 1/16 of “transmitted OFDM symbol”, Inter Symbol Interference (ICI) is not occurred. ISDB-T Latest Generation - 19.3M bps - 64QAM 8k 3/4 1/16 0,2s ISDB-T Previous Generation - 19.3M bps - 64QAM 8k 3/4 1/16 0,2s As a result, if multi-path delay time is no longer than GI, multi-path interference is As shown above, within guard interval length (+/- 63 us), ISDB-T work well almost almost compensated. 0dB D/U ratio. In addition, newest ISDB-T demodulator LSI adopt adaptive 67 compensation technology, so, widen the low D/U area up to 250us 68 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group Quad. modulation

8 MHz IF I signal Interpolation 5. ISDB-TSB transmission system multiplyer 37.15MHz FIR IF output SAW X ADD D/A filter

Q signal Interpolation 1. Outline of ISDB-TSB transmission system multiplyer FIR Lo. 2. Consecutive transmission system OSC 3. Example of consecutive transmitter station sin/cos gen. 8 MHz digital processing 32MHz digital processing Analog processing

(1) interpolation/FIR; convert from 8MHz sampling to 32 MHz sampling Relating clause of ARIB standard; B31 clause 3.12 – clause 3.15 (2) Quad. Mod.; multiply I and Q data and add, 32 MHz digital signal process. The output is 8MHz OFDM signal with 32MHz sampling (3) Analog circuit; up convert to 37.15 MHz IF and SAW filter. 69 70 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

ISDB-T transmission and partial reception 1. ISDB-TSB transmission system SB

(1) What is ISDB-TSB ISDB-TSB transmission system is unique in ISDB-T family. This transmission system has ISDB-T ISDB-T been standardized for narrow band ISDB-T transmission system, which is focused to SB audio and data service, therefore, called ISDB-TSB. Layer Layer B Layer A Example of A (2) Commonality with ISDB-T DTTB spectrum (a) Same segment transmission construction. But ,considering narrow band reception, Data segment only 1 segment and 3 segment transmission systems are standardized (b) Adopt same transmission parameters as ISDB-T. Channel coding & Segmented OFDM framing (c) Commonality of 1 segment receiver with ISDB-T partial reception Spectrum (3) Efficient use of frequency resource

(a) Consecutive transmission system. This system is unique for ISDB-TSB, this Partial 430kHz 430kHz transmission system is to transmit plural channel without guard band reception Partial (b) To achieve consecutive transmission, phase compensation technology at reception transmitter side is adopted 3-Segment receiver 1-Segment receiver 8192 FFT [mode 3]) (1024 FFT [mode3]) 71 72 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group Transmission parameters (continued) Transmission parameters

Mode 1 2 3 Mode 1 2 3 Segment(s) 1 or 3 Symbol duration 252μs 504μs 1.008ms Bandwidth 430kHz or 1.3MHz Guard interval 1/4 ～ 1/32 of symbol duration Carrier spacing 3.97kHz 1.98kHz 0.99kHz Symbols/frame 204 Total carriers 109 / 325 217 / 649 433 / 1297 ～～～ Data carriers 96 / 288 192 / 576 384 / 1152 Frame duration 53 64ms 106 129ms 212 257ms TMCC,AC,CP, Convolutional code 13 / 37 25 / 73 49 / 145 Inner code SP carriers (1/2, 2/3, 3/4, 5/6, 7/8) Modulation QPSK, 16QAM, 64QAM, DQPSK Outer code (204,188) RS code Interleaving Time and Frequency

73 74 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

Example of information bit-rate(TS rate) Spectrum utilization (1) 1segment 3segment note Broadcasting frequency bands are looked upon as a sequence QPSK, r=1/2,Tg=1/4 280kbps 0.84Mbps Minimum rate of segments,which have a bandwidth of one fourteenth of a TV QPSK, r=1/ 2,Tg=1/16 330kbps 0.99Mbps channel. BST-OFDM scheme provides followings. QPSK, r=2/3,Tg=1/16 440kbps 1.32Mbps

16QAM, r=1/2.Tg=1/16 660kbps 1.98Mbps -DTV uses 13 segments, remaining one ; guard band, -DSB uses 1 or 3 segments 64QAM,r=7/8,Tg=1/32 1.87Mbps 5.20Mbps Maximum rate -1-segment reception of 13 segment-TV signal by DSB receiver Bandwidth 430kbps 1.3Mbps -Consecutive-segment transmission without guard bands The information bit rates do not depend on transmission mode1,2 or 3, They depend on modulation ,coding rate and guard interval -systematic frequency re-packing towards total digital age 75 76 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group Frequency allocation of consecutive transmission Spectrum utilization (2) Concept of sub-channel Consecutive-segment Transmission of DSB channels 1/7 MHz Sub-channel- bandwidth=1/7 MHz Allocation of sub-channel Transmission from single transmitter keeping OFDM -condition Conventional allocation

3/7MHz Guard bands Example of allocation ISDB-TSB allocation with guard band … …

guard band guard band 1.3MHz 430kHz 430kHz 1.3MHz

ISDB-TSB allocation for consecutive Frequency utilization efficiency will be improved up to 150%. transmission 77 78 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

Why is the phase compensation of segment necessary Image of consecutive transmission and reception for consecutive transmission ?

A transmitter studioB Frequency allocation for 5 one segment Consecutive A B C D E f studio Segment channel consecutive transmission C Transmission A B C D MUX studioD MOD/PA Frequency Center of IFFT studio spectrum receiver Select channel D at receiver side D

Select required channel A B C D Center of FFT The center of IFFT and FFT is different , as a result, each carrier of received OFDM signal rotate during Guard interval period. (see next page) Audio/dada OFDM tuner/ This phase rotation is compensated at the trans- decoder DEM filter mitter side.

（digital terrestrial audio receiver) channel select 79 80 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group Phase rotation in every symbol Relationship between IFFT and FFT Tg=1/4*TS for consecutive transmission…… Center of FFT …… F =4/Ts Rotate 2*pai in F=2/Ts every symbol F=1/Ts FFT F=(4N+2)/Ts F=0 carrier Rotate 3*pai/2 F=(4N+1)/Ts F=-1/Ts in every symbol … F =3/Ts F=-2/Ts IFFT F=2/Ts Rotate pai in carrier F=1/Ts F =2/Ts every symbol Center of IFFT F=0 F=-1/Ts F=-2/Ts Rotate pai/2 in … F =1/Ts every symbol F=-(4N+1)/Ts Tg Ts F=(4N+1)/Ts

During guard interval (Tg) period, phase rotation (=2*N*pai*Tg/TS) occurs. (note) F=0 means the frequency Consequently, each carrier seems to rotate in every symbol period. 81 which is the center of FFT and IFFT 82 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

Phase of Each carrier in consecutive transmission Example of phase compensation F =(4N+2)/Ts Frequency slot No. Frequency slot No. Tg=(1/4)*Ts After phase compensation In every symbol, phase rotate pai Phase of each Without phase Center frequency Phase carrier at the compensation of FFT compensation at front end of transmitter side guard interval Pai rotate at the next symbol Center frequency of IFFT Receiver With phase No phase Transmitter side rotation side compensation Tg Ts

In case of consecutive transmission, center frequency of IFFT and FFT is different. Therefore, during guard interval, each carrier phase rotate according to above figure. In this example, center frequency of FFT is equal to F=(4N+2)/Ts of IFFT. Therefore, if Tg To avoid such phase rotation at receiver FFT, phase compensation is done at is equal to (1/4)*Ts, at the front end of every symbol rotate pai. transmitter side. 83 84 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group Phase compensation in every symbol ISDB-TSB studio & transmitter system for

Upper adjusent channel format consecutive transmission system

1 segment 3 segment

Service MUX (Consecutive Audio Audio transmitter MTX ENC GI mode 1 mode 2 mode 3 mode 1 mode 2 mode 3 station) U/C 1/32 -3/8 -3/4 -1/2 -6/8 -2/4 0 Authoring Data & terminal server 1/16 -3/4 -1/2 0 -2/4 0 0 segment combine PA 1 RE- FEC 1/8 -1/2 0 0 0 0 0 (broadcaster studio) MUX ENC …… …… 1/4 0 0 0 0 0 0 OFDM MOD 1/32 -6/8 -2/4 0 -1/8 -1/4 -1/2 Audio Audio Service MUX MTX ENC 1/16 -2/4 0 0 -1/4 -1/2 0 RE- FEC 3 MUX ENC 1/8 0 0 0 -1/2 0 0 Authoring Data terminal server 1/4 0 0 0 0 0 0 (broadcaster studio) TS interface Number of segment pf received channel 85 86 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group

Details of ISDB-TSB transmitter block diagram

System controller (SCS)

Broadcaster studio PA

SW END of Seminar #3

RE- FEC segment combine MUX ENC OFDM … … U/C Broadcaster MOD studio

SW Thank you for your attention RE- FEC (OFDM MUX ENC MOD) IF signal

Test signal Sync. signal Monitor GEN. GEN.

After RE-MUX , frame and clock of each channel are synchronized 87 88 DiBEG DiBEG Digital Broadcasting Experts Group Digital Broadcasting Experts Group