an initial study on the convergence of dvb-h and dtmb in the physical layer feng yang, jian song,...

An Initial Study on the Convergence of DVB-H and DTMB

in the Physical Layer

Feng Yang, Jian Song, Changyong Pan,Hui Yang, Kewu Peng, Jun Wang,

Zhixing Yang Dept. EE Tsinghua University

[email protected]

23.08.2007 ChinaCom2007 ShangHai 2

Brief Introduction of MING-T

MING-T = Multistandard Integrated Network convergence for Global Mobile and Broadcast Technologies

Main Objectives of the Project—…— Incorporate both DVB-H and DTMB into the multi-

standard framework.— ...

from project management handbook

Convergence of DVB-H and DTMB


Brief Introduction of MING-T (Cont’d)

— Prototype using two demodulators

— However, single chip is more attractive!

Tuner Tuner

DVB-Hdemodulator

DTMBdemodulator

DVB-HDriver/API

DTMBDriver/API

Middlewave

ESG Player

Laptop/PDA

Receiver


Comparisons of DTMB & DVB-H

Randomization

—Similarities The same PRBS, the same initial state

—Differences Sync byte: DVB (untouched) DTMB (Randomized) Reset: DVB (every 8 TS) DTMB (every signal frame)


Comparisons of DTMB & DVB-H (Cont’d)

Forward Error Correcting (FEC) coding—DVB-H : RS + Convolutional code

RS(204,188) derived from RS(255,239) Convolutional codes : 1/2, 2/3, 3/4, 5/6, 7/8

—DTMB : BCH + LDPC BCH(762,752) derived from BCH(1023,1013) LDPC with 3 code rates as the inner code



Interleaving —Convolutional interleaving

DTMB: B=52 M=240/720 DVB-H: B=12 M=17

1×M

2×M

3×M

…………………………………………

(B-1)×M

0 0

11

2 2

B-1

3 3

B-1

1×M

2×M

3×M

(B-1)×M

B-1 B-1

00

Interleaving Deinterleaving

…………………………………………

B-2

B-3

B-4 B-4

B-3

B-2



Interleaving —Block interleaving

DVB-H in-depth interleaver (8k)

DTMB frequency interleaver (4k)



Frame Structure

—C-OFDM : Process in Frequency domain—Parameter refresh : 1ms; Signal lock : 100ms

—TDS-OFDM : Process in Time/Frequency domain—Channel estimation : 0.56 ms; Signal lock : 5ms

PN Data PN Data

Signal Frame 500μsTDS-OFDM

Copy

CP Data+Pilot CP Data+Pilot

Copy

OFDM Symbol

C-OFDM



Summary —TDS-OFDM vs C-OFDM, Using PN brings

Higher spectrum efficiency Faster channel synchronization

—BCH+LDPC vs RS+Convolutional code for better coding gain, therefore, lower Eb/N0 required for the same BER

Larger coverage Better availability

—Long time-domain interleaver Better immunization to impulsive noise


Receiver Algorithms & Convergence Considerations

Synchronization—Correlation approach

DTMB: correlating with the known PN sequence DVB-H: guard interval correlation (pre-FFT syn.)

DownConverter

ADCCorrelator&memory of bigger size

RF

Channel estimation& equalization

?

Synchronization

?

Block De-interleaver

? ...

ConvolutionalDe-interleaver

?

FEC Decoder

De-scrambler

TS


Receiver Algorithms & Convergence Considerations (Cont’d)

Channel estimation & equalization—DVB-H: 8k FFT—DTMB: 8k FFT (channel estimation)

3780 FFT (equalization)

Correlator&memory of bigger size

RF


8K FFT3780 FFT

Synchronization

?


? ...

ConvolutionalDe-interleaverTS

DownConverter

ADC

?

FEC Decoder

De-scrambler



De-interleaving—Convolutional de-interleaver

DTMB: B=52, M=720 DVB-H: B=12, M=17

—Block de-interleaver DVB-H: 8K DTMB: 4K

Correlator&memory of bigger size

RF


8K FFT3780 FFT

Synchronization

8K


B=52M=720

...

ConvolutionalDe-interleaverTS

DownConverter

ADC

?

FEC Decoder

De-scrambler



FEC decoder—DVB-H

Convolutional code: Viterbi Algorithm (VA) RS code: syndrome computation, key-equation solver,

Chien search and error evaluator—DTMB (LDPC)

Hard-decision : Bit-Flipping (BF) Soft-decision : Sum-Product Algorithm (SPA)

FEC Decoder

LDPC Dec.(DTMB)

VA+

RS Dec.(DVB-H)

Thank you for your attention!

Email:[email protected]

an initial study on the convergence of dvb-h and dtmb in the physical layer feng yang, jian song,...

Documents

dtmb slide

fft dtmb

ts dtmb

block deinterleaver

dtmb frequency interleaver

known pn sequence dvbh

signal frame slide

inner code slide