WiBA New System Concept for DTT

Erik Stare, Teracom

Dr. Jordi J. Giménez, UPV

Dr. Peter Klenner, Panasonic Europe Ltd

Background 1

• 1992: First IBC in Amsterdam

– Scandinavian HD-DIVINE project

– Performed the world’s first HW demo of HDTV over DTT (OFDM)

– Slogan: ”One Big Step for Television”

– Enormously successful (”Digital terrestrial breakthrough steals show”)

• Triggered the creation of DVB in 1993

• The rest is history…

Background 2

• Situation today:

• Painful process to migrate to new broadcast standards

• Difficult to justify a new “DVB-T3” standard without radically improved performance & functionality

• Uncertain spectrum situation

• A small step is not enough…

• Is a “giant leap” possible?

Traditional frequency planning

-400 -300 -200 -100 0 100 200 300 400

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km

km

reuse-7

NOTE:Reuse is requiredalso with SFN at content borders!(e.g. reuse-4)

Only a fraction of the UHF channels are used from a given site

Shannon’s law and required power

• Capacity is proportional to SNR (power) in dB

• Required power increases exponentially with capacity

• High capacity also means high sensitivity to interference

Frequency

Power [W] (drawn to scale)

UHF1 UHF2 UHF3 UHF4 UHF5 UHF6 UHF7 UHF8 UHF24 UHF25 UHF26 UHF27 UHF28

DVB-T2

Mux 1

…

2500

DVB-T2

Mux 2

DVB-T2

Mux 6

No power

…

Required TX power for traditional DTTExtremely unbalanced RF power across UHF channels –

very bad from efficiency point of view!

• Bad for capacity• Bad for power

Earlier studies:Higher capacity and

lower power consumptionwith a lower reuse factor!

What about reuse-1?

Frequency

Power [W] (drawn to scale)

UHF1 UHF2 UHF3 UHF4 UHF5 UHF6 UHF7 UHF8 UHF9 UHF10

WiB…

UHF24 UHF25 UHF26 UHF27 UHF28

DVB-T2

Mux 6

DVB-T2

Mux 2DVB-T2

Mux 1 …

2500

50

17 dB difference

per RF channel

Factor 50!

WiB - Spreading the power equally over all frequencies

(reuse-1)

About 90% less total TX power by using all frequencies

Basic principles of WiB

• Wideband– Wideband transmission as a single WiB signal

• Covering potentially the whole 224 MHz UHF band (28 UHF channels)

– Reception with a ”Narrow-wide” (32 MHz) tuner• Allows for high service bit rates also with robust transmission mode

– Tuner frequency-hopping around the whole UHF band• Wideband frequency diversity

• Reuse-1– Adjacent TXs use the same frequencies

– Very challenging interference situation (e.g. C/I = 0 dB)

• Robust transmission mode required– e.g. QPSK, req. C/N close to 0 dB

• Interference Cancellation– Removes unwanted interference

WiB = ”WideBand reuse-1”

• High basic robustness (close to C/I=0 dB)

• Rejection via RX antenna

‒ Rooftop: Directional antenna

Antenna discrimination 16 dB (ITU)

‒ Mobile: Dynamic beamforming

• Interference cancellation

TX1

TX2

TX3

RX

SFN 1

SFN 2

SFN 3

RX

How to handle interference

TX1

TX2

TX3

RX

N=1

C3=1

C2=2

C1=4

N=1

C3=1

C2=2

Demodulated

and

cancelled

N=1

C3=1

Demodulated

and

cancelled

Demodulated

Required C/N = 0 dB (linear 1)

TX1

TX2

RX

Cancellation

of TX2

Interference cancellation

All TXs are synchronised (similar to SFN) but with different content and pilots

Receiver complexity

• A receiver is not expected to demodulate the 200-300 Mbps “supermux” as a whole– A receiver rather extracts a selected service and

demodulates only the associated part of the signal

• What we do have:– Factor 4 increase in sampling frequency and FFT size

due to wider tuner bandwidth

– Additional complexity for frequency-hopping tuner (e.g. TFS) is low

– Additional complexity for Interference Cancellation• but rather limited thanks to all TXs being synchronized

Network performance simulations

Time correlation type Best TX Wanted TX

Inter/Intra site (C) 3.41 bps/Hz 1.55 bps/Hz

Intra-site (U1) 3.38 bps/Hz 1.37 bps/Hz

No correlation (U2) 4.07 bps/Hz 1.60 bps/Hz

• Effective TX antenna height 250 m

• 60 km TX separation

• 1 kW ERP per UHF channel (17 dB lower than today)

• Propagation according to ITU-R P.1546

• Standard deviation: 5.5 dB (shadow fading) + 2.0 dB (frequency-dependent fading)

• Spatial correlation model

• Three different time correlation models (C, U1, U2)

• Directional RX antenna at 10 m (11 dBd gain, max 16 dB discrimination)

• Best TX case: The best TX is chosen irrespective of content

• Wanted TX case: A particular TX (with desired content) is required

• Interference cancellation of up to 2 TX signals

• Spectral efficiency calculated as average (normalized) Shannon capacity (95%

probability, 99% of time) in the worst point

DVB-T2 today: about 1 bps/Hz

System performance simulations• Network performance simulations have treated interference as noise

• At 1 bps/Hz no tolerance for noise at C/I=0 dB (Req. C/N=∞)

• However, possible to take into account the constellation of the interferer in the demodulation

• Allows QPSK demodulation (1 bps/Hz) at C/N=6 dB (instead of infinity) with 0 dB QPSK interferer

Potential for significant performance increase of network simulations

Statistical Multiplexing• With WiB statmuxing may be performed over a statmux pool

consisting of (up to) the capacity of the entire WiB signal (e.g. 200-300 Mbps within 470-694 MHz)

• Allows for close-to-ideal stamuxing also of UHD services

Time

Capacity

[Mbps]

TV service #4

TV service #3

TV service #2

TV service #1

PSI/SI, CA, bootloading etc

Reduced costs

• Capital Expenditures (CAPEX)– Single wideband TX

• Required total output power about half of one existing DTT TX

– No need for combiners - only a single wideband RF filter

– Lower equipment volume/weight• May allow mast positioning of the TX no RF feeder needed

– Lower performance requirements on TXs (linearity etc), due to robust transmission

– Drastically reduced need for cooling and backup power

• Operational Expenditures (OPEX)– >90% lower fundamental energy consumption

– Reduced maintenance need (less equipment, less sensitive, longer lifetime)

– No need for frequency planning and frequency changes

Combiner room today

Introduction scenarios

• Dedicated band approach

• Interleaved approach

Introduction scenarios -Dedicated band approach

DTT 470-862 MHz

DTT 470-790 MHz

DTT 470-694 MHz

DTT

800 MHz band

700 MHz band

WiB

800 MHz band

800 MHz band

WiB 470-694 MHz 700 MHz band 800 MHz band

700 MHz band

• International agreement on sub-band for WiB introduction

• Co-ordinated transition

• In the long term the whole 470-694 MHz band may be used for WiB

time

Introduction scenarios -Interleaved approach

UHF1 UHF2 UHF3 UHF4 UHF5 UHF6 UHF7 UHF8 UHF9 UHF10

…UHF24 UHF25 UHF26 UHF27 UHF28

UHF1 UHF2 UHF3 UHF4 UHF5 UHF6 UHF7 UHF8 UHF9 UHF10

…UHF24 UHF25 UHF26 UHF27 UHF28

Wanted

TX2

Interfering

TX1

T2 T2T2

T2 T2 T2

Power

• WiB is introduced ”interleaved” with existing DVB services

• WiB is transmitted with low power and, if necessary, with opposite

polarisation to minimise disturbance

Extension of the basic WiB concept(examples)

• Cross-polar MIMO (H + V polarisation on the same frequency)

– May further double the WiB capacity

– Could be backwards-compatible with legacy RX antennas• Sufficient separation via RX antenna polarization discrimination (16 dB)

• LDM-based combination of broadcast and unicast (mobile

telecom) in the same spectrum

– Transmission on the same time/frequency (e.g. on the same ”resource block”)

with controlled power difference

– Separated in the receiver by interference cancellation

Instead of this prolonged tug of war…

DTT spectrum Mobile Telecom spectrum

… why not this Win-Win peace project?

DTT

Mobile Telecom

Same spectrum(100% of time, 100% of frequency)

Mobile Telecom receivers firstdemodulate and cancel DTT

Mobile Telecom signals are”invisible” for DTT receivers

Controlled leveldistance

Separated viaInterferenceCancellation

A WiB VisionSame system/standard for broadcast and unicast

5G New Radio - Broadcast

5G New Radio - Unicast

Same system/standard

WiB gain summary

• Increased spectral efficiency

• Radically reduced network cost

• Unconstrained use of local services

• Close-to-ideal statmux gain (video coding)

– also for U-HDTV

• High speed mobile reception of all “roof-top” services

• Commercially acceptable introduction/migration scenarios

• Converged win-win solution with mobile telecom

Big enough leap?

Thank you for your attention!

For more information about WiB:

www.teracom.se/wib

WiB@IBC: 8.A50

(Progira Radio Communication booth)