Baseband Signal Vs Bandpass Signal 2

UEC Tokyo

IEEE The 2009 Int. Conf. Advanced Tech. for Communications

A New Concept of Baseband Radio

Yoshio KARASAWA

Advanced Wireless Communication research Center (AWCC) University of Electro-Communications (UEC Tokyo) UEC Tokyo

Presentation Topics

1. Baseband Signal vs Bandpass Signal 2. Wireless Baseband Transmission (WBT) 3. Experiment on Baseband Radio Adapting to Environmental Change 4. Radio Signal Processing Adaptive Array for Terrestrial Digital TV Signal under Multipath Environment UEC Tokyo

Wireless Transmission Scheme

Information Information

Coding Decoding Antenna Antenna Mod. (Tx) Propagation (Rx) Demod.

Carrier (radiowave) Multiple access UEC Tokyo

Wireless Baseband Transmission

Information Information

Coding Decoding Antenna Antenna (Tx) Propagation (Rx)

Carrier-less UWB-Impulse Radio (wireless impulse transmission) Wireless waveform transmission UEC Tokyo Data Transmission Scheme Information Carrier Modulated signal (a)

Information Extreme of Carrier modulated signal

(b)

It is equivalently a wireless baseband signal.

Baseband signal (complex signal) I += Q tsjtsts )()()(

time

= tsFfS )}({)( freq. 0

RF = tsts )}(Re{)( Band-pass signal (real signal) = I π − Qc π ctftstfts )2sin()()2cos()(

time

freq.

-fc 0 fc UEC Tokyo

Wireless transmission signal - time domain: real - freq. domain: complex Baseband signal - time domain: complex B B - freq. domain: complex freq.

B -fc 0 fc

freq. (b) RF signal transmission

-B/2 0 B/2 B B (a) Baseband signal freq.

-B/2 0 B/2 (c) Baseband signal transmission UEC Tokyo

The First Step: Wireless Baseband Transmission (WBT) UEC Tokyo

? UEC Tokyo Wireless Transmission Scheme

(a) Tx Data 1 0 1 0 0 1 1 1

(b) Manchester Coding

T0/2 Power Manchester coding Tx data (DC component is excluded.) Data transmission rate: 1/2

-2 -1 0 1 2 freq.

Frequency f (x 1/T0) UEC Tokyo

Transmission Discorn Antenna (freq: 100MHz to 500MHz) Experiment UEC Tokyo

Generated Signal to be Transmitted (after Manchester Coding) UEC Tokyo

Transmitted Amplitude

Received Amplitude UEC Tokyo

Data Detection

Received signal

after Manchester decoding

Error-free detection can be confirmed. UEC Tokyo

BER Characteristics of WBT UEC Tokyo

Result

Possibility of WBT has been demonstrated.

Positive feature of WBT

GHz frequency signal can carry Gbit data.

Antenna size of (10cm)3 can realize 2.5Gbps transmission. (confirmed)

Antenna size of (1cm)3 can realize 25Gbps transmission. (estimated) Problem to be solved Baseband Radio

There is an substantial interference problem like UWB-IR due to wide frequency band occupation. Accordingly, this scheme restricts application fields very strictly. UEC Tokyo

The Second Step: Baseband Radio UEC Tokyo

Three Radios Adaptive Communication

Baseband Radio Radio signal is directly generated based on digital signal processing without up conversion

Software-Defined Cognitive Radio Radio Available resources are All functions are realized utilized flexibly based on software based on environment programming recognition UEC Tokyo

Cognitive Radio (CR)

“cognitive” Recognition, Process of Understanding

Cognitive Radio (CR)

¾ Access method Adaptive radio system which can change ¾ Modulation scheme its system parameters autonomously, ¾ Frequency based on environmental sensing and ¾ Data rate intelligent judgement

Ultimate Efficient Use of Radio Frequencies Avoiding Radio Congestion UEC Tokyo

Baseband Radio

with Software-Defined Radio(*) and Cognitive Radio(**) functions

*) Kaleidoscopic change of configuration (reconfigurable) **) Recognition of radio encironment (intelligent) UEC Tokyo Cognitive Radio avoiding Radio Traffic Congestion based on Recognition of Radio Environment Change

Other primary service band but not used now Used in the primary service CNR Channel Available characteristics frequency band to be used in CR

CNR threshold

frequency UEC Tokyo Baseband Radio with Cognitive Radio Function

Time-varying usable frequency bands

Freq. f f 0 L1 fH1 fL2 fH2 L3 fH3

Environment Recognition

Time-varying Transmission Coding & Propagation Demod & Data Modulation Environment Decoding UEC Tokyo

Creation of Transmission Signal

Frequency band to be used in this communication

0 fmax Data allocation in the data block: a All null

Data to be K /2 Kb transmitted b Re{IFFT(a)} Signal to be transmitted

Baseband OFDM UEC Tokyo Baseband OFDM

Data to be transmitted Block a 0 0

0KB/2 KB

b = Re {IFFT (a)} Block b

DAC

Block b Signal is directly transmitted from the antenna without up conversion. UEC Tokyo

Basic Experimental Configuration and Procedure

Experiment procedure Discorn Discorn 1 Environment recognition antenna antenna 2 Channel sounding (using pilot signal) 3 Coding and Pre-distortion 4 Data transmission DAC ADC 5 Signal detection and analysis (FG) (DSO)

Performance of DAC & ADC PC Sampling rate of DAC in FG 250MHｚ Tx data Rx data Resolution of DAC 14bit Sampling rate of ADC DSO: Digital storage oscilloscope in DSO 250MHｚ FG: Function Generator Resolution of ADC 8bit UEC Tokyo Pre-Distortion

Channel characteristics Pre-distorted measured by pilot signal Tx signal CNR gain Threshold level Reference level

f1 f2 frequency f1 f2 frequency

Received signal without distortion CNR Wanted CNR

f 1 f2 frequency UEC Tokyo

Full range channel monitoring -60 10dB -80 Discorn Discorn antenna antenna -100

-120 FG DSO -140

-160 PC 相対利得[dB]

-180Relative power Tx data (full -200 range -220 pilot 0 20 40 60 80 100 120 signal) 周波数[MHz] Frequency (MHz) Allocated transmission frequency range UEC Tokyo

-60 -80 Pilot Signal Detection -100 -120 -140 -160 -180 相対利得[dB] -200 Discorn Discorn -220 antenna antenna

-240(10dB/div) Relative power 0 20 40 60 80 100 120 周波数[MHz] Frequency (MHz) FG DSO

0.1 16QAM

0.05 PC

0 Tx pilot -0.05 signal

-0.1

-0.1 -0.05 0 0.05 0.1 0.15 UEC Tokyo Pre-Distorted Tx Signal Based on the Pilot Signal Detection 20 0 -20 -40 -60 -80 -100 Discorn Discorn

相対利得[dB] -120 -140 antenna antenna -160

-180 (10 dB/dv) Relative power 0 20 40 60 80 100 120 周波数[MHz] Frequency (MHz) FG DSO

10 PC 5 Tx 0 pilot -5 signal -10

-15

-20 -25 -20 -15 -10 -5 0 5 10 15 20 25 UEC Tokyo Received signal after pre-distortion -60 -80 -100 -120 Discorn Discorn -140 -160 antenna antenna -180 相対利得[dB] -200 -220

Relative power (10 dB/div) FG DSO -240 0 20 40 60 80 100 120 周波数[MHz] Frequency (MHz)

0.04 PC Tx 0.02 pilot signal

0 Successful transmission of 16QAM

-0.02 based on “Baseband Radio” can be demonstrated!!

-0.04 -0.04 -0.02 0 0.02 0.04 UEC Tokyo Evolution of Wireless Terminal

Software-Defined Radio Hardware Technology Cognitive Radio All necessary functions Importance of RF circuit Environment recognition are created by software technologies is kept avoiding frequency programing forever. congection - Wideband antenna - Antenna array (MIMO) Digital Analogue - Tunable RF filter - Other RF circuits DAC/ADC

Wireless terminal Baseband Radio

Transmission signals are directly created by digital signal processing UEC Tokyo

Antenna Diversity based on Radio Signal Processing for Terrestrial Digital TV UEC Tokyo Terrestrial Digital TV Service in Japan

for In-house reception (12-segment HDTV) for mobile terminal (1-segment) (Existing analogue TV will be terminated in July, 2011 in Japan)

For reception in a vehicle, space diversity is indispensable. UEC Tokyo

Specification of Digital TV (ISDB-T)

Bandwidth 5.572 MHz

OFDM symbol period (Ts)1,008μs Guard Interval (TGI)126 μs The number of subcarriers 5,616 The number of segments 13 Primary Modulation 64QAM (HDTV) QPSK (1-seg.) TV channel 27ch（NHK-G）、 Carrier frequency 557.142857MHz UEC Tokyo Total Recording Radio Tower Radio signal Video signal

汎用パソコン PC DVD (Radio signal recording: Total recording) (Contents recording)

Recording of radio signal (IF signal) directly to HDD in PC Continuous recording of 200MB/s (=100MS/s) can be done. UEC Tokyo

Adaptive Array based on Radio Signal Processing

“Radio Signal Processing” which processes IF signal directly without demodulation and detection.

Application of this scheme to the maximal ratio combining diversity scheme with subband signal processing for mobile reception of terrestrial digital TV broadcasting signal . UEC Tokyo Baseband Signal Processing and Radio Signal Processing

Band-pass signal (real-domain signal)

freq.

-fc 0 fc Baseband signal (complex-domain signal) freq. 0 Baseband Signal Processing

freq.

-fc 0 fc Radio Signal Processing UEC Tokyo Radio Signal Processing Adaptive Array

IF signal TV tuner IF IF signal signal IF-to-BB Radio conversion ADC Signal and Processing De- modulation

Local Adaptive digital signal processing Oscillator using RF or IF signals before Demodulation and Detection UEC Tokyo

IF signal for antenna A1 (real-domain signal) Radio Signal Processing (OFDM block Extracted symbol-by-symbol base)

t = 0 t = TB FFT Signal band: S +(f) f = -fs/2 f = fs/2

A4 - 0Hz Frequency domain Copy & Paste SB-MRC analysis (frequency-inverted and complex conjugated) 0 0 0 IFFT

Combined signal- UEC Tokyo Maximal-Ratio Combining with Subband Signal Processing

Divide signal frequency band Group m into M small groups

A1 1 2 m M

A2 1 2 m M The validity of the scheme A3 1 2 m M has been confirmed A4 1 2 m M through field experiments (off-line proc.)

R(m) R(m): Correlation matrix

Obtaining the largest Eigen value wm and its Eigenvector UEC Tokyo

Antenna Antenna ＃２ Antenna ＃３＃１ Antenna ＃４ UEC Tokyo

Demonstration of MRC reception based on Radio Signal Processing

(omitted) UEC Tokyo

Diversity Effects (Analyzed based on RSP)

1 Single Service area improvement antenna 0.8 reception

0.6 2-element Diversity CNR improvement

0.4 Cumulative probability Cumulative 4-element Cumulative probability 0.2 Diversity

0 0 5 10 15 20 25 30 CNRCNR (dB) UEC Tokyo

The Three Radios, again Adaptive Communication

Baseband Radio Radio signal is directly generated or analyzed as if it is baseband signal

Software-Defined Cognitive Radio Radio Available resources are All functions are realized utilized flexibly based on software based on environment programming recognition