ITU-R SG8 Seminar on Tomorrow’s Technological Innovations

Geneva, Switzerland

September 9, 2004

Carl R. Stevenson, Agere SystemsSlide 1

Exploring the Feasibility and Benefits of Additional Uses of Unused TV

Broadcast Spectrum

Carl R. StevensonSr. Manager, Standards & Regulatory Affairs, Agere SystemsChair, IEEE 802.18 Radio Regulatory Technical Advisory GroupChair, IEEE 802.18 SG1 (SG on License-Exempt Use of Unused TV Spectrum)Interim Chair, IEEE 802.22 (pending) Working Group On WRANs4991 Shimerville RoadEmmaus, PA 18049 USAE-mail: carlstevenson@agere.com carl.stevenson@ieee.org

ITU-R SG8 Seminar on Tomorrow’s Technological Innovations

Geneva, Switzerland

September 9, 2004

Carl R. Stevenson, Agere SystemsSlide 2

Introduction

• The goal of this presentation is to:• Acknowledge the importance and value of TV broadcasting• Show that large amounts of the TV broadcast allocations are unused or underused (and why)• Examine the feasibility and benefits of additional uses of that unused TV spectrum• Inform ITU-R SG8 of ongoing studies and standards activities aimed at additional, non-interfering uses of this spectrum• Encourage regulators to consider how such additional , non-interfering uses can provide public benefit and increase the efficiency of spectrum utilization

ITU-R SG8 Seminar on Tomorrow’s Technological Innovations

Geneva, Switzerland

September 9, 2004

Carl R. Stevenson, Agere SystemsSlide 3

Clearly, TV broadcasting is an important and valuable use of

spectrum

• The value of TV broadcasting is not in question• TV broadcasting provides many important benefits:

• News and weather• Entertainment• Educational• Cultural• Other

ITU-R SG8 Seminar on Tomorrow’s Technological Innovations

Geneva, Switzerland

September 9, 2004

Carl R. Stevenson, Agere SystemsSlide 4

However …• Much spectrum allocated for TV is unused/underused

• Particularly in sparsely populated areas, where few TV stations exist• But, even in more densely populated areas, some channels are unused• This is necessary to prevent interference between TV stations• Co-channel separation between TV stations must be large

• Overlapping coverage areas would cause interference• Technical limitations of TV receivers render other channels “off-limits”

• Dynamic range• Adjacent channel rejection• Intermodulation, etc.

• Result: many TV channels are unused over significant geographical areas

ITU-R SG8 Seminar on Tomorrow’s Technological Innovations

Geneva, Switzerland

September 9, 2004

Carl R. Stevenson, Agere SystemsSlide 5

Example 1 – Channel 5 in the Eastern US(graphic courtesy of Shared Spectrum Co. from a contribution to IEEE 802.18 SG1)

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ITU-R SG8 Seminar on Tomorrow’s Technological Innovations

Geneva, Switzerland

September 9, 2004

Carl R. Stevenson, Agere SystemsSlide 6

Example 2 – Channel 54 in the Eastern US(graphic courtesy of Shared Spectrum Co. from a contribution to IEEE 802.18 SG1)

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ITU-R SG8 Seminar on Tomorrow’s Technological Innovations

Geneva, Switzerland

September 9, 2004

Carl R. Stevenson, Agere SystemsSlide 7

Conclusion: there is much unused or underused spectrum in the TV bands

(sometimes referred to as “white space”)

• Could this spectrum be used for other uses, without causing interference to the primary broadcast use?• The answer is “almost certainly so”• The major issues are:

• Must assure non-interference to primary TV use• This is a fundamental requirement

• The availability of “white space” is highly variable• Channel by channel and area by area• Terrain variations and other factors affect availability• In some areas, some TV stations are not active 24/7

• Therefore, systems designed to use this “white space” should:• Intelligently sense environment• Reliably and robustly determine channel availability• Not transmit on channels where interference would result• Be adaptable to changes in incumbent (TV) use• Be technically and economically feasible• Provide a valuable service to justify use of the spectrum

ITU-R SG8 Seminar on Tomorrow’s Technological Innovations

Geneva, Switzerland

September 9, 2004

Carl R. Stevenson, Agere SystemsSlide 8

Can these issues be satisfactorily addressed?

• Initial studies in IEEE 802.18 SG1 show promise• TV signals have unique spectral characteristics• TV transmitters are powerful

• This facilitates Incumbent Profile Detection (“IPD”)• With a limited set of incumbent “signatures” IPD is easier• The nature of TV spectral signatures also makes IPD easier

• Generally high transmission power• Known, unique spectral signatures• TV transmissions are more continuous than intermittent• TV transmitters located at fixed locations • Applies to both analog and digital TV systems

• Cognitive Radio (“CR”) techniques appear to be a promising approach to reliable interference avoidance

ITU-R SG8 Seminar on Tomorrow’s Technological Innovations

Geneva, Switzerland

September 9, 2004

Carl R. Stevenson, Agere SystemsSlide 9

Example 1: Analog TV (NTSC) Spectrum(this slide courtesy of John Notor of Cadence Design Systems, Inc.)

• Power primarily confined to Video and Audio carriers.

• Distinctive double peaked spectrum makes identification by spectrum profiling relatively easy.

• Relatively high narrowband power levels compared to DTV.

ITU-R SG8 Seminar on Tomorrow’s Technological Innovations

Geneva, Switzerland

September 9, 2004

Carl R. Stevenson, Agere SystemsSlide 10

Example 2: Digital TV (ATSC) Spectrum(this slide courtesy of John Notor of Cadence Design Systems, Inc.)

• Power spread over center 5.38 MHz within a TV channnel.

• Pilot tone is a distinctive feature when observed in a narrowband receiver.

• Pilot tone power is 11.3 dB below average power measured in a 6 MHz bandwidth.

ITU-R SG8 Seminar on Tomorrow’s Technological Innovations

Geneva, Switzerland

September 9, 2004

Carl R. Stevenson, Agere SystemsSlide 11

Example of Co-Channel Interference Range Margin From Initial Studies

(this slide courtesy of John Notor of Cadence Design Systems, Inc.)

DTV Service Area

Edge ofDTV

ServiceContour

Limit of CRDTV

SensingCapability

Sensing Margin:48–116 km

CR Range to 23 dB D/U Limit

17.1 < R < 32.4 km(+36 dBm EIRP)

R

D/U Range Margin:15.6–93.3 km

ITU-R SG8 Seminar on Tomorrow’s Technological Innovations

Geneva, Switzerland

September 9, 2004

Carl R. Stevenson, Agere SystemsSlide 12

Are solutions to the issues of sharing this unused spectrum on a strictly non-interfering basis

economically realizable with today’s technology?

• Studies to date indicate “yes”• Ultimate solution still being defined, but key components appear to be:

• Use of Cognitive Radio (“smart radio”) technology• To identify channels that can be used without causing interference• To adapt to changing or intermittent spectrum use by TV stations

• Transmitter Power Control to limit interference range

ITU-R SG8 Seminar on Tomorrow’s Technological Innovations

Geneva, Switzerland

September 9, 2004

Carl R. Stevenson, Agere SystemsSlide 13

Overview of Activities in this Area in the IEEE 802 Standards Committee

• Study group (IEEE 802.18 SG1) chartered under parentage of IEEE 802.18 in November 2003• Efforts of the Study Group to date

• Evaluate candidate applications for standardization in terms of “best and highest use of the spectrum”• Do preliminary studies of interference avoidance methods• Prepare a Project Authorization Request (“PAR”) seeking to form a new standard development Working Group within IEEE 802

•Results to date• PAR approved by Study Group, IEEE 802.18, and the IEEE 802 Executive Committee at the July 2004 IEEE 802 plenary

• Pending final approval by the IEEE-SA Standards Board on September 23, 2004, the first meeting of new WG (IEEE 802.22) is anticipated to be held at the November 2004 IEEE 802 plenary• In the meantime, work continues in the Study Group

ITU-R SG8 Seminar on Tomorrow’s Technological Innovations

Geneva, Switzerland

September 9, 2004

Carl R. Stevenson, Agere SystemsSlide 14

Abstract of the Proposed IEEE 802.22 PARPurpose of the PAR (note as of the time of this presentation this PAR will not yet have gained final approval by the IEEE-SA Standards Board):To gain approval to start a new Working Group to develop a new IEEE 802 StandardProposed title:Standard for Information Technology -Telecommunications and information exchange between systems – Wireless Regional Area Networks (WRAN) - Specific requirements - Part 22: Cognitive Wireless RAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Policies and procedures for operation in the TV BandsScope of the Project:This standard specifies the air interface, including the medium access control layer (MAC) and physical layer (PHY), of fixed point-to-multipoint wireless regional area networks operating in the VHF/UHF TV broadcast bands between 54 MHz and 862 MHz.Purpose of Proposed Project:This standard is intended to enable deployment of interoperable 802 multivendor wireless regional area network products, to facilitate competition in broadband access by providing alternatives to wireline broadband access and extending the deployability of such systems into diverse geographic areas, including sparsely populated rural areas, while preventing harmful interference to incumbent licensed services in the TV broadcast bands.Reason for the standardization project:There is a large, untapped market for broadband wireless access in rural and other unserved/underserved areas where wired infrastructure cannot be economically deployed. Products based on this standard will be able to serve those markets and increase the efficiency of spectrum utilization in spectrum currently allocated to, but unused by, the TV broadcast service.

ITU-R SG8 Seminar on Tomorrow’s Technological Innovations

Geneva, Switzerland

September 9, 2004

Carl R. Stevenson, Agere SystemsSlide 15

Why should regulators consider alternative uses of unused TV broadcast spectrum?

• To promote more efficient use of the spectrum • To enable the provision of additional services to the public• One of the most compelling service candidates appears to be fixed broadband wireless access, particularly in rural and other unserved/underserved areas

• Favorable propagation characteristics for f < 1 GHz• Lower propagation loss• Better foliage/building penetration• Better for NLOS links

• More capable of economically serving widely dispersed users than systems operating at much higher frequencies

ITU-R SG8 Seminar on Tomorrow’s Technological Innovations

Geneva, Switzerland

September 9, 2004

Carl R. Stevenson, Agere SystemsSlide 16

Thank you for your attention!

Any questions?