WiB A New System Concept for DTT Erik Stare, Teracom Dr. Jordi J. - - PowerPoint PPT Presentation

WiB

A 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

100 200 300 400

• 300
• 200
• 100

100 200 300

1

2 3 4 5 6 7

1

2 3 4 5 6 7

1

2 3 4 5 6 7

1

2 3 4 5 6 7

1

2 3 4 5 6 7

1

2 3 4 5 6 7

1

2 3 4 5 6 7 km km

reuse-7 NOTE: Reuse is required also 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 DTT

Extremely 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 consumption with 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 2 DVB-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

• f 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 T2 T2 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 first demodulate and cancel DTT Mobile Telecom signals are ”invisible” for DTT receivers Controlled level distance Separated via Interference Cancellation

A WiB Vision

Same 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)