Planning 71-76-81-86 Ghz Bands Millimetre

Planning of the 71-76 GHz and 81-86 GHz Bands for Millimetre Wave High Capacity Fixed Link Technology

December 2006 Spectrum Planning Discussion Paper SPP 2006-11

© Commonwealth of Australia [2006] This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without prior written permission from the Commonwealth. Requests and inquiries concerning reproduction and rights should be addressed to the Manager, Communications and Publishing, Australian Communications and Media Authority, PO Box 13112 Law Courts, Melbourne Vic 8010.

Published by the Australian Communications and Media Authority Canberra Central Office Melbourne Central Office Sydney Central Office Purple Building, Benjamin Offices Level 44, Melbourne Central Tower Level 15, Tower 1 Darling Park Chan Street, Belconnen 360 Elizabeth Street, Melbourne 201 Sussex Street, Sydney PO Box 78, PO Box 13112 Law Courts PO Box Q500 Belconnen ACT 2616 Melbourne Vic 8010 Queen Victoria Building NSW 1230

Tel: 02 6219 5555 Tel: 03 9963 6800 Tel: 02 9334 7700, 1800 226 667 Fax: 02 6219 5200 Fax: 03 9963 6899 Fax: 02 9334 7799

TTY: 03 9963 6948

Australian Communications and Media Authority i

Purpose

The purpose of this paper is to invite comment on the proposed use of the 71-76 GHz and 81-86 GHz bands for wireless point-to-point services including carriage of broadband wireless technology.

Issue for comment

ACMA seeks comment on:

• whether the proposed coordination arrangements are appropriate for the proposed spectrum use including whether the proposed database recording method, and self-coordination, arrangements are appropriate;

• which licensing methodology is preferred; and • any other relevant matters that should be considered.

Comments on the proposals contained in this paper may be forwarded to:

Manager Spectrum Engineering Section Australian Communications and Media Authority PO Box 78 Belconnen ACT 2616 Fax: 02 6219 5254 Email: [email protected]

Comments should arrive at ACMA by close of business on 28 February 2007.

Enquiries may be directed to Snezana Krusevac on 02 6219 5582 or Email: [email protected]

Publication of submissions

In general, ACMA publishes all submissions it receives.

ACMA prefers to receive submissions which are not claimed to be confidential. However, ACMA accepts that a submitter may sometimes wish to provide information in confidence. In these circumstances, submitters are asked to identify the material over which confidentiality is claimed and provide a written explanation for confidentiality claims.

ACMA will consider each claim for confidentiality on a case by case basis. If ACMA accepts a confidentiality claim, it will not publish the confidential information unless required by law to do so.

When can ACMA be required by law to release information?

Any submissions provided to ACMA may be released under the Freedom of Information Act 1982. ACMA may also be required to release submissions for other reasons including for the purpose of parliamentary processes or where otherwise required by law (for example a court subpoena). While ACMA seeks to consult submitters of confidential information before that information is provided to another body or agency, ACMA cannot guarantee that confidential information will not be released through these or other legal means.

Australian Communications and Media Authority ii

Contents 1. INTRODUCTION ..................................................................................................................... 1

2. SYSTEM OVERVIEW ............................................................................................................. 2

3. CURRENT TECHNOLOGY .................................................................................................... 6

4. PROPAGATION AT 70 AND 80 GHz..................................................................................... 9 4.1 ATTENUATION............................................................................................................. 9 4.2. RANGE AVAILIBITY ................................................................................................ 12

5. SURVEY OF OVERSEAS REGULATORY ARRANGEMENTS........................................ 14

6. INTERNATIONAL AND AUSTRALIAN FREQUENCY ALLOCATION ......................... 18 6.1 CURRENT SPERCTRUM PLAN ARRANGEMENT AND USAGE......................... 18 6.2 SUMMARY OF SERVICES ALLOCATION AND USAGE WITHIN THE 71-76 GHz AND 81-86 GHz BANDS................................................................................................... 19 6.3 SHARING BETWEEN FIXED AND OTHER SERVICES......................................... 20

7. INTERFERENCE RISK ANALYSIS ..................................................................................... 22 7.1 INTER-LINK INTERFERNCE ANALYSIS AS RECOMMENDED BY WIRELESS COMMUNICATION ASSOCIATION............................................................................... 22 7.2 THE INTERFERENCE RISK TO RADIO-ASTRONOMY RECEIVERS ................. 27 7.3 THE INTERFERENCE RISK FROM VEHICLE RADAR OPERATING IN THE 76 – 77 GHz BAND .................................................................................................................... 29 7.4 CHANNEL PLANNING AND GUARD BANDS ....................................................... 31

8. TECHNICAL STANDARDS AND HUMAN EXPOSURE LIMITS .................................... 33 8.1 TECHNICAL STANDARDS ....................................................................................... 33 8.2 HUMAN EXPOSURE LIMITS .................................................................................... 33

9. LICENSING CONSIDERATIONS......................................................................................... 35 9.1 OVERSEAS LICENSING ARRANGEMENTS........................................................... 35 9.2 LICENSING OPTIONS IN AUSTRALIA ................................................................... 36

10. DISCUSSION AND RECOMMENDATIONS .................................................................. 38 10.1 DISCUSSION ............................................................................................................. 38 10.2 RECOMMENDATIONS ............................................................................................ 39

REFERENCES................................................................................................................................. 40

Australian Communications and Media Authority iii

1. INTRODUCTION

The use of broadband wireless technology to provide access to the internet and other high-speed networks is attractive to operators because of its low construction cost, quick deployment, and flexibility in providing access to a range of services.

The broadband wireless technology known as millimetre-wave, pencil beam or gigabit-wireless spectrum is designed to operate in the spectrum of 71-76 GHz and 81-86 GHz. This high capacity point-to-point fixed link technology provides up to 10 GHz of bandwidth and enables a transmission rate of a several Gbps even with a relatively simple modulation scheme such as amplitude modulation. With a more spectrally efficient modulation scheme such as 4-level FSK (Frequency Shift Keying), full duplex data rates of 10 Gbps can be reached. With direct data conversion and low cost diplexers, relatively simple and thus cost efficient radio architectures can be realised.

A significant difference between fixed wireless point-to-point systems operating in the 71-76 GHz and 81-86 GHz bands, relative to fixed wireless point-to-point systems operating in lower-frequency bands, is the availability of antennas with narrower radiation pattern (beamwidth). Thus, millimetre wave technology could provide minimal interference to other adjacent links except those lying directly along the intended path. As a consequence, there is potential to relax the technical criteria for spectral re-use and concentrate on rules governing the spatial extent of the transmitted beam. Simply put, operations in the band might be parcelled geographically more than spectrally.

Atmospheric absorption varies significantly with frequency. At conventional microwave frequencies up to 20 GHz, atmospheric absorption is reasonably low, until rising to a peak around 60 GHz, where absorption by oxygen molecules results in an attenuation of 15 dB/km, seriously limiting radio transmission distances. After this peak, a large frequency window opens, where the attenuation drops to less than 1 dB/km (effectively negligible) before rising again due to other molecular effects. Thus, the spectrum band from around 70 GHz to around 120 GHz exhibits low atmospheric attenuation and is relatively unused.

In summary, the propagation characteristics at the 71-76 GHz and 81-86 GHz bands allow for high capacity broadband transmission and is useful for communication paths of up to 3 km using simple and relatively cheap technology while providing carrier class performance.

Australian Communications and Media Authority 1

2. SYSTEM OVERVIEW

The range of applications for services using the 71-76 and 81-86 GHz bands is wide and evolving quickly. It includes voice, data, and entertainment services of many kinds. Each user may require a different mix of services. Traffic flow may be unidirectional, asymmetrical, or symmetrical, and this balance will change with time and application. These radio systems compete with other wired and wireless delivery means for “first mile” connections to wired services. Use of radio or wireless techniques could be beneficial in a number of ways, including rapid deployment and relatively low establishment costs.

Fibre

Metropolitan Area

Networks

POP (Point of Presence) Fibre Hotel

Fibre

Figure 1. Typical Deployment


Potential Applications

� Fibre (Backbone) POP Access � Redundant Access - Network Diversity

� Enterprise Campus Connectivity

� Local Area Network (LAN) Extension

� Local Loop

� Metropolitan Area Network (MAN)

� Wide Area Network (WAN) Access

� Central Office Bypass

� Storage Access

� Wireless Backhaul

� High Definition Video

Network recovery In the case of fibre breakage, the temporary service restoration could be delivered more rapidly by the means of radio backup. The major advantage of this technique is its shorter set-up time in comparison with the time needed to restore the original fibre link.

Broken Fibre

~1.5 km

POP (Network Point of Presence) – Fibre

Figure 2: Network recovery


Campus LAN Further extension of fibre-optic communication networks with gigabit wireless LANs and private networks is possible. Furthermore, high-speed (gigabit) access will be maintained within the wireless part of network as well as in the rest of fibre-optic communication network, but without problems and expenses connected with fibre installation.

Fibre Telephone Central Office

POP (Point of presence) Fibre Hotel

Figure 3: Campus LAN


Storage access Machine to machine connectivity for the storage area networks could be easily established, with excellent data security and high availability.

Fibre

~1.5 km

Desktops Remote Data Storage

Server

Figure 4: Storage access

Wireless backhaul Wireless broadband technology with its possibility of very high data rate can be used for third generation (3G) cellular or WiMAX backhaul in dense urban environments. Additionally, portable and temporary links for high definition video or high definition television (HDTV) transport can be built by applying this technology.

WiMax

Point-to-Multi-point WiMax Point-to-Point

WiFi Hot-Spots

Access Points

Cell Phones

Cell Tower Backhaul

WiFi Backhaul

WiMax Backhaul

Figure 5: Wireless backhaul


3. CURRENT TECHNOLOGY

GigaBeam GigaBeam Company provides multi-gigabit wireless communication solutions for the “entire last mile". They manufacture, lease, install, and service high-speed point-to-point wireless communication access system. GigaBeam was instrumental in opening up the 71-76 GHz and 8186 GHz bands in the USA.

Features of the GigaBeam products:

• Antennas: flatplate and parabolic designs, ranging from 12 inches to 24 inches across (depending on network design requirements)

• Speeds: from 1.25 Gbps to 10 Gbps • Redundancy: simplex single links to full-duplex auto-failover systems • Security: multiple encryption levels and network encryption reliance • Protocols: supporting virtually any protocol, just like a fibre splice

Loea Corporation Loea Corporation is a designer and manufacturer of ultra broadband fixed wireless telecommunication equipment operating in the upper millimetre wave spectrum from 71-86 GHz. Loea claims to have been the first company to demonstrate a 71-86 GHz radio system in 2001 and first to achieve certification of a 71-86 GHz transceiver from the FCC in 2005.

Features of the L2500 Transceiver:

Upper millimetre-wave spectrum operation

• Beamwidth - 0.4 degree • Antenna gain 51 dBi • On-off keying (OOK) modulation scheme • Optical carrier level 12 (OC-12)– 622 Mbps – full duplex • Gigabit Ethernet– 1.25 Gbps – full duplex • Duplex data rates up to 1.5 Gbps

OSI Layer 1 (Physical Layer) Operation

• Compatible with most switches, routers and encryption devices

Weather performance

• 99.999% weather availability at approximately 1 km • 99.9% weather availability at approximately 3 km

Power

• Transmitter output power at antenna port > 10 mW


E-band corporation E-band corporation designs and manufactures multi-gigabit capacity wireless communication systems based on 71-86 GHz millimeter-wave radio technology. The use of MMIC (Monolithic Microwave Integrated Circuit) technology enables manufacturing of high performance wireless systems with 1 to 10 Gbps throughput over distances of several kilometers and availability up to 99.999%. MMIC technology used in E-band communications products is provided by Northrop Grumman Corporation.

E-link product features: • Carrier-grade availability

• Full Duplex data-rate from 1.25 Gbps to 10 Gbps

• Path length from 1 to 10 km (1 - 6 Miles)

• MMIC to deliver more reliability and reproducibility in increased volumes

• High security level

• Protocol independent, just like fibre optics

Rayawave Rayawave is a company that manufactures millimetre-wave RF components and designs wireless systems architecture and antennas for 70/80 GHz outdoor links as well as 60 GHz indoor and outdoor links.

Their wireless systems design is based on “Convolution Lossless Feeding” technique that enables deployment at distances up to 5 km and at availability of 99.999% or better.

Endwave Endwave Corporation designs and manufactures RF modules that enable the transmission, reception and processing of extremely high-frequency signals (1-100 GHz) in wireless telecommunications networks. Their transmitter and receiver modules for point-to-point radio subsystems are based on MMIC technology.

Northrop-Grumman (Velocium) Velocium Products is a business unit of Northrop Grumman Space Technology. Their production line encompasses a broad range of products based on MMIC technology for microwave and millimetre-wave applications. They manufacture amplifiers, mixers and other complementary components covering DC to 100 GHz frequency band. In addition, Velocium manufactures the following products for 70/80 GHz links:

• Low Noise Amplifiers

• Power amplifiers


• Mixers

• Multipliers and switches

Intel Intel is a merchant supplier of chips, MMICs and RF sub-assemblies. They are working on CMOS MMICs for up to 100 GHz.


4. PROPAGATION AT 70 AND 80 GHz

4.1 ATTENUATION

Free Space Path Loss The free space path loss model is used to predict received signal strength when the transmitter and receiver have a clear, unobstructed line-of-sight path between them. Free space path loss LdB at distance d and frequency f can be calculated by using the following equation

L = 92.4 + 20log f + 20log ddB GHz km (1)

Under stable, well-mixed atmospheric conditions free space attenuation is about ~130 dB/km within the 71-76 GHz band and ~131 dB/km within the 81-86 GHz band.

Atmospheric attenuation Atmospheric attenuation varies significantly with frequency [1] as shown in Figure 6. At lower microwave frequencies (up to 20 GHz), atmospheric attenuation is reasonably low at a few tenths of dB/km. A large peak is seen around 60 GHz where absorption by oxygen molecules seriously limits radio transmission distances. After this peak, however, a large window opens up where attenuation drops to 0.5 dB/km. After 100 GHz, atmospheric attenuation generally increases as there are numerous molecular effects including O2 and H2O absorption at higher frequencies. It can be seen that the spectrum from around 70 GHz to 100 GHz exhibits low atmospheric attenuation. Therefore, the band is suitable for wireless communication.

Figure 6: Atmospheric attenuation vs. frequency


Rain attenuation Radio propagation within the millimetre band (30 – 300 GHz) is characterised by very high rain attenuation [2]. This will impose limitation on the link distances.

When an electromagnetic wave propagates through a rain cell, it encounters a great amount of water droplets with different radii. The cumulative effect of attenuation suffered by an electromagnetic wave penetrating a rain cell is considered here.

Figure 7. depicts the rain attenuation as a function of frequency and rain rate [2]. While, the rain-attenuation as a function of rain fall rate for the 71-76 and 81-86 GHz bands is presented in Figure 8. For the case of very severe (tropical) rainfalls (100 mm/hr), the attenuation can reach up to 30 dB/km, but this generally occurs only in short bursts. Such severe weather tends to fall in small, dense clusters within a larger, lower intensity rain cloud, and is usually associated with a severe weather event that moves quickly across the link path. Therefore, rain outages tend to be short term and are only problematic on longer-distance transmission.

Figure 7: Rain attenuation vs. frequency


0 10 20 30 40 50 60 70 80 90 100 0

5

10

15

20

25

30

35

Rain Rate [mm/h]

Rai

n A

ttenu

atio

n [d

B/k

m]

71 GHz Horizontal pol. 86 GHz Horizontal pol. 71 GHz Vertical pol. 86 GHz Vertical pol.

Figure 8. Rain Attenuation versus Rain Rate for 70/80 GHz links

10 20 30 40 50 60 70 80 90 100 2.25

2.3

2.35

2.4

2.45

2.5

2.55

2.6

2.65

2.7

2.75

Rain Rate [mm/h]

Dia

mat

er o

f Rai

n C

ell [

km]

Figure 9. Estimated Rain Cell Diameter versus Rain Rate

In addition, the rain cell diameter is calculated for different rain rates in Figure 9, which will be required for the interference analysis.

Clouds of ice crystals and snow do not cause appreciable attenuation, even if the rate of fall exceeds 125 mm/h. This is due to the much-reduced loss of ice compared to water. Similar effect on the propagation results from dust, sand and other path impairments. For example, thick fog at a density of 0.1 g/m3 (about 50 m visibility) has just 0.4 dB/km attenuation at 70/80 GHz [3].


E

N

Foliage and Vegetation Loss The foliage losses at millimetre wave frequencies are significant. In fact, the foliage loss may be a limiting propagation impairment in some cases. An empirical relationship has been developed [4], which can predict the loss. For the case where foliage depth is less than 400 m, the loss is given by

0.3 0.6= 0.2 f RLdB (2)

where f is frequency in MHz, and R is depth of foliage in metres.

This relationship is applicable for frequencies in the range 200 MHz-95 GHz. For example, the foliage loss at 70 GHz for a penetration of 10 m (which is about equivalent to a large tree or two in tandem) is about 50 dB.

Penetration Loss When millimetre-waves are propagated through various materials, they are more or less strongly attenuated. Since, the point-to-point links considered in this report are designed for direct line-ofsight applications in an outdoor environment a detailed analysis of penetration loss is not considered necessary.

4.2. RANGE AVAILIBITY The International Telecommunication Union (ITU) and other bodies have collected decades of rain data from around the world, so rainfall characteristics are well-understood [5]. With such information, it is possible to predict the levels of weather outage on longer links. In Table 1, the maximum link distances for 99.9%, 99.99 % and 99.999% availability for different regions of Australia, according to notation at Figure 10, is given.

E

F

K M N

P

Figure 10. Map of Australia showing ITU standard rain zone


Rain Zone

Availability

E F K M N P

99.9% 3800 m 3200 m 2700 m 2500 m 2200 m 1800 m

99.99 % 1950 m 1600 m 1350 m 1200 m 900 m 800 m

99.999% 1200 m 950 m 820 m 700 m 550 m 480 m

Table 1 – Typical Range and Availability of 70/80 GHz links

In addition, the link distance as a function of rain rate for different antenna dish diameters is presented in Figure 11 [7].

Figure 11. Link range versus rain rate for various antenna dish diameters [6]


5. SURVEY OF OVERSEAS REGULATORY ARRANGEMENTS

International Telecommunication Union According to the ITU Radio Regulations, the 71-76 GHz and 81-86 GHz bands are available for fixed and mobile services (among others) in all three ITU regions. There are however no specific recommendations regarding the use of these bands or sharing arrangements with other services.

United States of America The Federal Communication Commission (FCC) is the United States government agency responsible for regulating non-government interstate and international communications by radio, television, wire, satellite and cable.

In October 2003, FCC allocated the 71-76 GHz, 81-86 GHz and 92-95 GHz bands to both Federal Government and non-federal Government users on a co-primary basis, except the 94-94.1 GHz portion, which is allocated for exclusive Federal Government use [7].

In general, the 71-76 GHz, 81-86 GHz and 92-95 GHz bands are licensed on a non-exclusive basis. This new concept, called light licensing, comprises of registering each path on the date in a database. In that way, the licensees will generally be provided interference protection on a link-bylink basis, with the priority being set based on the date of link registration.

In addition, the 92.0-94.0 GHz and 94.1-95.0 GHz bands can be used as unlicensed bands, but for indoor applications.

The FCC divided the 71-76 GHz and 81-86 GHz bands into four unpaired 1.25 GHz segments (eight in total), without mandating specific channels within the “soft” segments and these segments may be aggregated without limit.

Technical recommendations can be summarised as follows:

• Antenna shall have a minimum antenna gain of 43 dBi and a maximum 1.2 degree half-power beamwidth

• The maximum transmit power spectral density shall be 150 mW/100 MHz

• Previously registered links are protected to 1.0 dB of degradation for a baseband signal-tonoise (S/N) ratio for analog modulation. Also, a 1.0 dB receiver threshold-to-interference (T/I) ratio degradation limit for digital systems is adopted.

• The FCC shortened the traditional 18-months construction requirement to 12 months.


Canada Canada has adopted the same bands, with the same technical specifications and licensing regimens as the USA [8].

Europe The European Radiocommunications Office (ERO) was established in May 1991 as permanent office of the European Conference of Postal and Telecommunication Administration (CEPT) to provide support to the European Communications Committee (ECC) on radio and telecommunication matters. It represents 47 European spectrum regulators.

ECC/REC (05) 07 [9] defines the channel arrangements for the 71-76 GHz and 81-86 GHz bands. Within each 5 GHz bandwidth, nineteen 250 MHz channels are defined, with a 125 MHz guard band at the bottom and top of each 5 GHz band. Aggregation of any number of channels, from 1 to 19, is permitted. Furthermore, the specified channels may be used for either time division duplex (TDD) or frequency division duplex (FDD) systems within the single band, or in combination with other bands.

The technical requirements for millimetre wave equipment operated in the fixed service in the 7176 GHz and 81-86 GHz bands are described in [10], and can be summarised as:

• The antenna gain shall be a minimum of 43 dBi;

• The maximum EIRP shall be equal +45 dBW;

• The maximum total output power at antenna port shall not exceed 30 dBm;

• The maximum radio frequency tolerance shall not exceed ±150 ppm.

Final allocations of frequencies and definition of licensing regimes in Europe is developed by national administrations. There is no simple position, despite all national administrations expressing full support for the ECC process.

Estonia, Lithuania and Finland have released the bands 71-76 GHz and 81-86 GHz on a fully-licensed basis. Switzerland has released the 71-76 GHz and 81-86 GHz bands on a conventional, fully-licensed basis due to sharing with military. The Czech Republic and Slovenia have released the bands 71-76 and 81-86 GHz on a lightly-licensed basis.

Germany and Denmark have not released any bands yet, but have said that they consider opening on lightly-licensed basis. France is reserving its position, pending the outcome of various ECC decisions.


United Kingdom Ofcom regulates UK communication industries and spectrum usage. It has responsibilities across television, radio, telecommunications and wireless services.

In November 2006, Ofcom released a document to open the 71-76 GHz and 81-86 GHz bands for point-to-point broadband fixed wireless systems on a light licensed basis [11].

The Ofcom recommendation can be summarised as:

• Flexible Band Plan is adopted, where a 4.75 GHz block is available in both 71-76 and 81-86 GHz bands, with a 125 MHz guard band at the top and the bottom of each 5 GHz band to ensure adjacent band compatibility;

• The band will be open on non-exclusive national licence basis. The licence term will be indefinite with a 5 year notice period for revocation;

• Light licensing arrangement with e-enabled link registration process is adopted. The online facility will not perform detailed link budget and assignment calculation. It is expected that the licenses would carry out this functions themselves or employ the services of a third party to advise them in relation to interference management;

• Links will be self-coordinated i.e. coordinating between links will be the responsibility of the licence holder. In cases where coordination is not possible, then the earlier registered link will have priority. If an interference case results, then the later link will be removed from the register;

• The maximum EIRP for the 71-76 and 81-86 GHz bands shall be equal +55 dBW;

• The maximum total output power at antenna port shall not exceed 0 dBW;

• In order to give as much control as possible to the market, interference criteria will not be specified by Ofcom. Instead the licensees will have the responsibility to assess the interference potential to existing links. This together with the ability to self coordinate gives the licensees the freedom to plan and negotiate with other users of the band based on their specific systems.


Summary

FCC Ofcom ERO

Power spectral density limit

150 mW/100MHz

Max EIRP for spectrum band

+55 dBW

Max EIRP for spectrum band

+45 dBW

Max transmit power limit (at antenna port)

+30 dBm

Max transmit power limit (at antenna port)

+30 dBm

Minimum antenna gain

43 dBi

Minimum antenna gain

43 dBi

NA Maximum radio frequency tolerance

±150 ppm

Non-exclusive nationwide licences

Non-exclusive national licences

NA Link registration – First-in time standard

E-enable link registration – with first in time priority

Table 2. Overview of the arrangements for 71-76 and 81-86 GHz links in the USA, UK and Europe


6. INTERNATIONAL AND AUSTRALIAN FREQUENCY ALLOCATION

6.1 CURRENT SPERCTRUM PLAN ARRANGEMENT AND USAGE Band [GHz] International (Region 1,2, and 3) Australia

71-74 FIXED FIXED-SATELITE (Space-to-Earth) MOBILE MOBILE-SATELITE (Space-to-Earth)

FIXED FIXED-SATELITE (Space-to-Earth) MOBILE MOBILE-SATELITE (Space-to-Earth)

AUS62 74-76 FIXED

FIXED-SATELITE (Space-to-Earth) MOBILE BROADCASTING BROADCASTING-SATELITE Space-research (Space-to-Earth)

559A, 561

FIXED FIXED-SATELITE (Space-to-Earth) MOBILE BROADCASTING BROADCASTING-SATELITE Space-research (Space-to-Earth)

559A, 561, AUS62

81-84 FIXED FIXED-SATELITE (Earth-to-space) MOBILE MOBILE-SATELITE (Earth-to-space) RADIO-ASTRONOMY Space-research (Earth-to-space)

149, 560A

FIXED FIXED-SATELITE (Earth-to-space) MOBILE MOBILE-SATELITE (Earth-to-space) RADIO-ASTRONOMY Space-research (Earth-to-space)

149, 560A, AUS62 84-86 FIXED

FIXED-SATELITE (Earth-to-space) MOBILE RADIO-ASTRONOMY

149

FIXED FIXED-SATELITE (Earth-to-space) MOBILE RADIO-ASTRONOMY

149 Table 3. Extract from the Australian Radiofrequency Spectrum Plan Table of Allocations

The 71-76 GHz and 81-86 GHz bands cover four bands of spectrum allocations as shown in the Table 3. In the Australian Radiofrequency Spectrum Plan (ARSP) fixed and mobile services are allocated to all four bands on a primary basis.


6.2 SUMMARY OF SERVICES ALLOCATION AND USAGE WITHIN THE 71-76 GHZ AND 81-86 GHZ BANDS

Fixed and Mobile services

All four bands (defined in the spectrum plan) within the 71-76 GHz and 81-86 GHz bands have allocations for Fixed and Mobile services.

Fixed-satellite service Bands within the 71-76 GHz spectrum bands have allocations for space-to-Earth fixed-satellite services. While bands within the 81-86 GHz band have allocations for Earth-to-space fixed-satellite services.

Mobile-satellite service The 71-74 GHz band has allocation for space-to-Earth mobile-satellite services. While the 81-84 GHz band has allocation for Earth-to-space mobile-satellite services.

Broadcasting and Broadcasting-satellite

The 74-76 GHz band is also allocated for broadcasting and broadcasting-satellite services.

Radio Astronomy Radio Astronomy (81-84 GHz and 84-86 GHz bands) is based on the reception of the radio waves of cosmic origin. Particular attention should be taken to assure adequate protection of the specific band 85.05-85.42 GHz within the band 81-86 GHz, as it is on the list of the most important astrophysical spectral lines [12].

Space research service The bands 74-76 GHz and 81-84 GHz have allocations for the space research service (space-to-Earth), but on the secondary basis.

Table 4. Service allocations within the 71-76 GHz and 81-86 GHz bands


6.3 SHARING BETWEEN FIXED AND OTHER SERVICES

Radio Astronomy Service According to International footnote 149, it is advised that steps be taken to protect radio astronomy observations from harmful interference when planning allocations of other services to the 81-84 GHz and 84-86 GHz bands. In the next section, notification zones are recommended to protect radioastronomy services of the Paul Wild and Mopra observatories as they operate in the 81-84 GHz and 84-86 GHz bands [13].

Mobile Service There is a limited potential for outdoor mobile applications in the 71-74 GHz and 81-84 GHz bands because of high attenuation and line-of-sight propagation in these bands. Interference from 70/80 GHz point-to-point links to mobile services is highly unlikely due to the use of narrow beamwidth antennas that are proposed for these applications.

Broadcasting and Broadcasting-Satellite Services The 74-76 GHz band is also allocated for the broadcasting and broadcasting satellite services. However, there are no current plans to use this band in Australia for broadcasting proposes and future proposals along those lines would seem unlikely due to the high atmospheric losses.

Space Research Service The Australian Space Research Institute is a non-profit organisation, and it has been founded in order to develop and advance Australian space science and technology. From the available projects data of the Australian Space Research Institute, there is no indication that the 71-76 and 81-86 GHz bands might be used for purposes of the space research in the near future.

Fixed-Satellite Service In Australia, fixed-satellite services are primarily delivered within C-band (3.4-4.2 GHz for downlink and 5.85—6.65 GHz for uplink) and Ku-band (11.45-12.75 GHz downlink and 14-14.5 GHz for uplink), and as such their operations will not be affected by fixed point-to-point services in 70/80 GHz band. On the other hand, advance notice of the VINASAT-3B2 satellite that will possibly use the 71-75 GHz band has been submitted to the ITU by the Vietnam Posts and Telecommunications Group (VNPT). The coverage area of this satellite includes Australia. However, the first Vietnamese satellite VINASAT-1 is only planned to be launched in 2008, and there is no available date for the launching VINASAT-3B2, but it is not expected to be in the near future. Therefore, it is not possible to provide a detailed interference analysis at this stage.


Mobile-Satellite Service No evidence of demand for the use of the 71-76 and 81-86 GHz bands for mobile-satellite services is known to ACMA at this stage, and it seems unlikely that these bands would be considered for mobile-satellite services due the high atmospheric losses.

Amateur and Amateur-Satellite Service International footnote 559A, allocated the band 75.5-76 GHz to the amateur and amateur-satellite services on a primary basis until the year 2006. The band 81-81.5 GHz is also allocated to the amateur and amateur-satellite services on a secondary basis until 2006.

In Australia, the conditions of amateur operation are defined by the Radiocommunications Licence Conditions (Amateur Licence) Determination No. 1 of 1997 (Amateur LCD) [14]. Although amateur licence conditions were recently updated in October 2005, the bands 71-76 GHz and 8186 GHz are not within the permitted amateur bands. Therefore, the amateur and amateur-satellite services are excluded from further consideration about interference that might be caused by the possible introduction of 71-76 or 81-86 GHz fixed point-to-point links.

Defence use Potential future defence interest in the use of 71-74 GHz, 74-76 GHz and 81-84 GHz bands is indicated by footnote AUS62 [13]. The Department of Defence has been consulted regarding their potential interest in these bands.

In summary, except for Radioastronomy services that is proposed to be protected by the notification zone, as it will be defined in Section 7.2, ACMA is not aware of any other existing systems that might be affected by deployment of fixed links in these bands.


7. INTERFERENCE RISK ANALYSIS

7.1 INTER-LINK INTERFERNCE ANALYSIS AS RECOMMENDED BY WIRELESS COMMUNICATION ASSOCIATION

The focus in this section is on unchannelised coordination with the worst-case assumptions, i.e. cochannel interference coordination.

The primary source of interference for narrow-beam 70/80 GHz links is line-of-sight power directed into the main lobe or a sidelobe of a victim receive antenna. Other effects such as multipath and atmospheric stratification are not significant for operation in this band due to the extremely narrow beams in which the radiation propagates.

In [15], the interference analysis is based on threshold-to-interference (T/I) ratio. It is recommended that successful path coordination should guarantee that interference could never cause carrier-to-interference (C/I) level to be less than the manufacturer recommended T/I level (Figure 12), except in special cases (such as very short link path lengths) where the service availability of the affected receiver will always remain acceptable despite the interference.

Unfaded RF Receive level

C/I 10-6 BER Static Threshold

C/N Unfaded Inference Level IUF

Thermal Noise Level T/I

6 dB Objective for 1dB Threshold

Rain Faded Interference level IF

Figure 12. Signal level diagram relating receiver carrier, threshold, and noise floor levels with faded and unfaded interference objectives levels [15]

The advantages of using T/I-based criteria are that the difference in thresholds, due to bit rate, modulation technique (transmission efficiency), coding gain and noise figure, are all taken into account, and that the absolute level of allowable interference can be easily determined by subtracting the T/I ratio from the static threshold (defined for bit-error-rate equal to 10-6) of particular digital receiver.


Adaptive Transmit Power Control

Heavy rain limits the opportunity for full implementation of point-to-point systems in terms of installation distances and frequency usage (Section 4.1). One possible solution to overcome the rain attenuation problem is the use of an Adaptive Transmit Power Control (ATPC) system incorporated in the front-end of the radio-unit. For the 70/80 GHz Bands, guidelines for ATPC system are proposed in [15], and the maximum ATPC dynamic range is (0, EIRPdBW=23) [15]. Therefore, it is very important that the ATPC system is taken into consideration for the purposes of the interference analyses. Analysis steps to determine interference for several possible scenarios

In order to determine possible interference in the proximity of the observed receiver, the following steps are recommended by Wireless Communication Association in [15].

1. All links placed within the radius of 100km around the midpoint of a proposed link should be included for possible interference assessment, while those beyond this radius may be eliminated.

2. The clear-air interference calculations are based on the worst-case from each registered transmitter in the area into each proposed receiver including the atmospheric loss of the area; nominally it is 0.4 dB/km. The worst-case assumption is the case when the desired signal is fully rain-faded and the interferer signal has no rain fading. Cases that show interference 6 dB below the receiver thermal noise power may be eliminated from further consideration.

3. For some link geometries, paths may be near enough in azimuth that they are affected by the same rain cell and thus have correlated rain fading1. The range of azimuth can be calculated as (Figure 13)

rθ = 2arctan( )d (3)

d

angle θ r

Rain cell

Figure 13. Included angle to assume rain fading

A rain event consists of small “volume cells” of intense rain rate within much larger “debris regions” with a lower rain rate. The dimensions of these areas are inversely related to rain rate. In the debris region, rain rate tends to be approximately log-normally distributed with a low median. In one example, the median rate was only 0.7 mm/h, whereas volume cells within the region had rates as high as 32 mm/h. Thus a conservative model for interference assumes that when the worst

1 Data on the spatial correlation of the rain event is scant. However, a rudimentary model can be based on work published in [16].


case rain fade of the desired signal occurs, any interfering signal travels only through the debris region and experiences a low rain rate fade.

The following examples are given to facilitate determination of the possible worst-case scenario under different weather conditions. The criterion (4) has to be satisfied in the following cases:

C / I ≥ T / IActual Required (4)

1. The victim link carrier level to reach the static threshold

2. The victim link ATPC (Adaptive Transmit Power Control) to begin to increase the transmitter power

3. The interfering link ATPC to reach maximum power

Example 1

Approximately Collinear Desired and Interfering Propagation Paths

A B

D

C

Rain

Figure 14. Rain fading geometry – ATPC power increase at A does not increase interference at D

If the interference path from interfering transmitter to victim receiver is within the included angle θ, as illustrated in Fig. 13, then the interference at D from transmitter A under clear-air conditions is the highest that will occur. Under clear-air conditions, transmitter A will be using its reduced ATPC power.


Example 2

Interference Entering Victim Antenna Near Boresight Direction

A D

C

B

Rain

Figure 15. Rain fading geometry – desired signal fading equal to interference signal fading

A rain cell that affects the desired signal path (C-D link) attenuates the desired signal, and attenuates the interference signal by an equal amount.

A D

C

B

Rain

Figure 16. Rain fading geometry – desired signal fades less than interfering signal

A rain cell that occurs beyond the desired link may attenuate the interference signal while not affecting the desired signal.

Therefore, the interference level and C/I ratio that are calculated under clear-air conditions are worst–case values that will not be degraded by the rain.


Example 3

Desired and Interference Propagation Paths within a Rain Cell

A D

C

B Rain

Figure 17. Rain fading geometry – equal rate-of-fading of interference and desired signals

In this case, C/I analysis is recommended. Based on the minimum 2km rain cell diameter, the analysis is recommended when the interfering link, the victim link, and the path of inference are located within 1km of the victim receiver. For example, the calculation is done for 9dB/km of the rain attenuation, and it seems that the lighter rain regime could be more critical causing the link to fail [15].


7.2 THE INTERFERENCE RISK TO RADIO-ASTRONOMY RECEIVERS

The Paul Wild and Mopra observatories operate in the band 75-115 GHz. Part of the band, 76-86 GHz is protected with the ITU footnote 149. But, only 81-86 GHz band is potentially subject to interference from the high capacity fixed point-to-point links. Hence the protection of the radio astronomy services within the band 81-86 GHz will be the focus of analysis in this section.

Location Latitude/Longitude Frequency band

(GHz)

Spectral power

flux-density

(dB(W/(m2⋅Hz)))

Paul Wild Observatory Narrabri

30°18’52.0”S

149°32’56.3”E 75-115 -2222

Mopra Observatory

Coonabarabran 31°16’4.5”S

149°5’58.7”E 75-115 -2222

Table 5: Radio astronomy observatories, their locations, geographic co-ordinates, operating frequency bands and protection requirements

In [18], notification zones are defined for apparatus licensed services around radio astronomy facilities. The purpose was to prescribe a process for notification of prospective frequency assignment to apparatus licensed services that might impede or degrade the operation of radio astronomy facilities. However, considering that the 81-86 GHz band is not taken into consideration in [18] it is necessary to calculate the notification zone radius for the 81-86 GHz band that would be adequate to avoid possible interference arising from the use of the fixed point-to-point links in the 71-76 and 81-86 GHz bands.

Based on the Recommendation ITU-R RA.1031-1 [19], transmission loss can be calculated as

( ) = P +G +G − P (p)L pb t t r r

In this analysis, transmission loss comprises free-space propagation loss and atmospheric absorption loss.

2 Spectral power flux density is determined based on the Recommendation ITU-R RA.769 [17] for the 81-86 GHz band.


Pt - transmitting power level (dBW) 0dBW

Gt - gain (dBi) of the transmitting antenna in the direction of the radio astronomy antenna 50dBi3

Gr - gain (dBi) of the receiving antenna in the direction of the transmitter

0dBi4

Pr(p) – maximum permissible interference power (dBW) in the 81-86GHz band to be exceed for no more than p% of time at the

receiver input -130dBW5

Atmospheric absorption 0.5dB/km

Notification zone radius 25km

Table 6: Input parameters for the notification zone radius calculations

3 Antenna gain is taken as typical from the manufacturer’s product specification lists (Section 3).

4 Based on the Recommendation ITU-R RA.769 [17], for the assessment of interference to radioastronomy from transmitter used for terrestrial radiocommunications, a value of 0 dBi is adopted for the gain of the radioastronomy antenna in the direction of the horizon.

5 Many radioastronomy measurements can tolerate levels of interference from a shared service which exceed these thresholds for 10% of the time. Maximum permissible interference power is found from spectral power flux density [19] for the 81-86 GHz band.


7.3 THE INTERFERENCE RISK FROM VEHICLE RADAR OPERATING IN THE 76 – 77 GHZ BAND

In this section, we will discuss interference risk from the out-of-band and spurious emissions from vehicle radar operating in the 76 GHz to 77 GHz range on fixed wireless point-to-point link operating in the 71-76 and 81-86 GHz band.

Firstly, we define out-of-band emissions and spurious emissions. Out-of-band emissions are residual emissions related to the intentional emissions radiated by the antennas on the frequencies immediately outside the permitted range of frequencies which may result from the modulation process. Spurious emissions are emissions radiated by the antenna or the transmitter cabinet on a frequency, or frequencies, outside the permitted range of frequencies occupied by the transmitter. Spurious emissions include harmonic emissions, parasitic emissions, intermodulation products, but exclude out-of-band emissions

While there is no specific requirement for the minimal level of spurious and out-of-band emissions from the vehicular radar operating in the 76-77 GHz band that has been specified by the ACMA, for the purposes of the interference risk analysis, the FCC and ETSI recommended levels [20,21] will be used. The ACMA may consider including such requirements, or impose more rigorous ones, within a future revision of the low interference potential device (LIPD) class licence to minimize the risk of interference in adjacent spectrum.

The recommendations for vehicle radar system operation within the band 76-77 GHz are defined in the FCC report and order [21]. It is specified that the power density of any emission outside the operating band shall be considered to consist solely of spurious emissions. Furthermore, the limits for radiated emissions outside the operating band and between 40 GHz and 200 GHz, measured at a distance of 3 m from the exterior surface of the radiating structure, shall not exceed the limits given in the Table 7 [21].

Type of vehicle mounted sensors Power density limit [pW/cm2]

forward-looking sensors 600

side-looking or rear-looking sensors 300

Table 7: FCC limits for spurious emissions

The requirements for vehicle radar operation in the frequency range between 76 GHz to 77 GHz are also specified by ETSI [21]. It is defined that the mean power spectral density radiated outside the 76 GHz to 77 GHz band shall not exceed the values shown in Table 8 [21].

Frequency range [GHz] Maximum mean power spectral density (dBm/MHz)

73.5 -76 0

77 – 79.5 0

Table 8: ETSI limits for out of band radiation


In addition, the effective radiated power spectral density of any radiated spurious emission shall not exceed the values given in Table 9 [21].

Frequency range [GHz] Limit value for spurious radiation (dBm/MHz)

40 – 100 -30

Table 9: ETSI limit for radiated spurious emissions

The interference risk from the vehicular radars can be reduced by implementing antennas with narrow-beam radiation pattern for vehicle radar as well as for the link. However, the above limits will apply only for the fundamental frequency band, for vehicle radar in the 76-77 GHz band. Furthermore, the radars will operate while vehicle are travelling uphill, downhill, and around curves, so specifying beam-width limits will not stop the radar beam from illuminating off road objects.

As a worst case scenario, the link budget calculation is presented in Table 10 when the interferer is the vehicle radar. The interference analysis is based on the Wireless Communication Association recommendation [15] also presented in Section 7.1, when the out-of-band emissions are restricted as in Table 8.

Parameter Link Interferer-to-link

Carrier frequency [GHz] 75.75 75.75

EIRP [dBm] 536 24

Bandwidth [MHz] 250 250

NF [dB] 8

Noise power [dBm] -81.8

Rain attenuation [dB/km] 9

Path length [km] 1.5 1

Received antenna gain [dBi] 50 50

Received power [dBm] -38.0 -56.0

Received C/(N+I) [dB] 18.0

Required SINR [dB] 14

Required T/I [dB] 19.9

Link margin -1.9

Table 10: Interference Risk 6 The value is chosen as the maximum transmitter output level which does not need to employ ATPC based on the WCA recommendation [15]


The interference analysis is based upon a comparison of C/(N+I) in service with manufacturer-specified T/I limits for a digital receiver. The static threshold of a digital receiver, T, is defined as the manually faded (with attenuators) receive carrier level that produces a bit-error-rate (BER) of 10-6. Values of T/I are roughly 6 dB greater then the theoretical threshold values of C/N under the assumption that the interferer is a (worst case) thermal-noise like interference with a bandwidth less or equal to that of the desired signal. Theoretical C/N requirement for some common schemes include OOK or BPSK (C/N=13 dB), QPSK (13.5), 4FSK (17.5 dB) and 16QAM (20.9 dB), and hence T/I is taken to be 19.9 dB.

Based on the interference link analysis illustrated in Table 10, if the link is partially affected by light rain, the received carrier to interference-plus-noise ratio C/(N+I) may fall 1.9 dB below the required level causing the link to fail. Although, the interference to a link is likely to be restricted to very short periods of time from an individual vehicle, with increasing traffic flow of vehicles equipped with automotive radar operating in the 76-77 GHz band, the link availability of wireless point-to-point link operating in the 71-76 and 81-86 GHz band might be significantly degraded.

The interference risk from vehicular radar can be reduced in several ways. Firstly, by the implementation of automatic transmit power control (ATPC). In such a way, the ATPC system could provide protection against rain outage, and in the particular case illustrated in Table 10, protection against harmful vehicle radar interference.

Secondly, the implementation of guard bands will provide greater opportunity for the natural roll off of emissions outside the band. It is the implementation of these guard bands as proposed by ETSI and Ofcom [10,11] that might explain why interference from vehicular radar is not discussed.

7.4 CHANNEL PLANNING AND GUARD BANDS

In this section, we will discuss potential interference to and from adjacent bands and propose a solution to minimise the risk of interference to and from fixed point-to-point and other services in the millimetre band.

Firstly, in the previous section, the potential interference risk from the spurious and out-of-band emissions from vehicular radar operating in the 76-77 GHz band has been discussed. Although, the minimum level of spurious and out-of-band emissions was not specified by ACMA, the out-ofband emissions are implicitly restricted by defining transmitter “99% power” emission bandwidth [22]. Namely, the occupied bandwidth is defined as the band which leaves 0.5% of the signal power above and 0.5% of the signal power below the bandwidth limits. In such a way, the band contains 99% of the signal power.

By applying the transmitter “99% power” emission bandwidth and taking into account that the maximum permissible EIRP emitted by the vehicle radar within the 76-77 GHz band is 25 W, the emissions in the 125 MHz adjacent bands may achieve the significant level given in Table 8, also recommended by the ETSI [21].

Secondly the adjacent 86-92 GHz band is allocated to the Radio Astronomy, Earth-Exploration Satellite and Space Research Services. It has been proposed in this paper to protect the radio astronomy service through the application of notification zones. While the Earth-Exploration Satellite and Space Research Services are allocated in the Australian Radiofrequency Spectrum


Plan, there are as yet no other regulatory arrangements or channel plans or assignments in the band. Nevertheless, all emissions are prohibited by footnote 340 [13] and care should be taken when planning services in the adjacent bands due to out-of-band and spurious emissions.

Additionally, the 77-81 GHz band (the ‘79 GHz range band’) has been designated for use by automotive short range radars in ECC decision [25]. Although, the equipment shall be designed to operate with a maximum mean power density of -3 dBm/MHz (and peak power of 55 dBm EIRP) and vehicles shall be equipped with 79 GHz automotive radar from 2013, adequate planning of services in the adjacent bands may improve the level of radio spectrum efficiency.

Therefore, the minimum interference environment for the operation of the fixed point-to-point 70/80 GHz links might be achieved by introducing a 125 MHz guard band at the top and bottom of each 5 GHz band. The positions of the guard bands should be in line with the CEPT [9] and Ofcom arrangements [11].

Finally, a channel plan should not be defined in the 71.125-75.875 GHz and 81.125-85.875 GHz bands. It is proposed that by not insisting on using a specific channel plan, equipment with a variety of modulation schemes may be utilised encouraging further technological development.


8. TECHNICAL STANDARDS AND HUMAN EXPOSURE LIMITS

8.1 TECHNICAL STANDARDS

The Institute of Electrical and Electronics Engineers – Standards Association (IEEE-SA) has not issued any particular standards for operation within the 71-76 GHz and 81-86 GHz bands. However, the IEEE 802.18 Radio Regulatory Technical Advisory group has commenced work towards such standards based on FCC WT Docket No. 02-146 [23].

8.2 HUMAN EXPOSURE LIMITS

Power density limitation for general safety requirements are specified in Radio Protection Standards issued by the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA).

In frequency range above 6 GHz and up to 300 GHz, basic restrictions are provided on both instantaneous and time averaged incident power flux density (Table 11.) to prevent excessive heating in tissue at or near the body surface and to protect against effects associated with extremely high level pulsed fields.

Exposure category

Frequency range

Time averaged power flux density [W/m2]

Instantaneous power flux density [W/m2]

Occupational 6-300 GHz 50 50 000

General public 6-300 GHz 10 10 000

Table 11. Basic restriction for time averaged and instantaneous incident power flux density

The maximum power flux density expected in the radiating near field can be estimated using the following equation

4P ⎡ W ⎤Surface power denisty = 2A ⎢⎣m ⎥⎦

where P denotes the net power delivered to the antenna in [W], and A denotes the physical area of the aperture in [m2].

Considering the practical dimensions of the antennas discussed in Section 3, the smallest antenna aperture area which will produce the maximum surface power density, for a 30 cm diameter dish is


500 cm2. Then the maximum power delivered to the antenna which satisfies the general public exposure level can be calculated as follows

500 ⋅10−4

P = 10 ⋅ W = 125mW 4

The calculated value is lower than the maximum transmit power of 1 W (30 dBm) recommended by overseas regulatory bodies (FCC, ECC and Ofcom) [7,10,11]. When considering possible regulatory arrangements for the use of this equipment in Australia, the need for proper care should be noted during the link installation process to meet the occupational and general public exposure criterion.


9. LICENSING CONSIDERATIONS

9.1 OVERSEAS LICENSING ARRANGEMENTS

The unique characteristics of the links operating in the 71-76 GHz and 81-86 GHz bands provide an opportunity to utilise more flexible licensing arrangements and several different approaches have been taken overseas.

Flexible Licensing Approach (USA and possibly Canada) The FCC has adopted a flexible and innovative regulatory framework for the 71-76 GHz and 8186 GHz bands. Rights with regard to specific links are established based upon the date and time of link registration. Therefore, a first-in-time criterion is adopted in order to protect the first-in-time registered or incumbent links.

Furthermore, all licensees are required to obtain and submit an interference analysis to a third party manager as a part of link registration. The aim is to minimise the adverse economic impact on licensees, including those that are small entities. In adopting the interference-analysis requirements, the cost and benefits of imposing an interference analysis requirement are considered, especially for small entities. In an FCC survey, it was found that the cost of performing such analyses would be relatively small, particularly when compared with the benefits of preventing harmful interference to existing operations for all licensees. Three database managers, FFI, Micronet and Comsearch use distinct but centralised databases, offering the choice to the user community while ensuring a centralised format for available link information.

Light Licensing Approach (UK, possibly Germany and some other European countries) The deployment under a licence exempt basis could result in unacceptable interference and would be unlikely to lead to optimal use of the spectrum, particularly considering the high availability applications proposed to be used in the bands.

On the other hand, the potential for interference is likely to be small in the bands due to the ‘pencil beam’ signal characteristics of the fixed wireless systems. Therefore, a simple mechanism which enables individual 70/80 GHz links to gain protection from interference can be accomplished by the implementation of a centralised database with a registration system with a first come first served data and time record essentially forming the basis for protection.

Fully Licensed Approach (Finland, Switzerland and Estonia) The 71-76 and 81-86 GHz bands are fully licensed. The coordination is necessary to ensure that services neither suffer from, nor cause, interference.


9.2 LICENSING OPTIONS IN AUSTRALIA

The Radiocommunications Act 1992 requires that the operation of all radiocommunications devices must be authorised under one of three licence types: apparatus, class or spectrum licences.

Apparatus licensing Traditionally, apparatus licences are issued to authorise the operation of fixed point-to-point services in the microwave bands. Apparatus licences are usually issued ‘over the counter’, and require payment of an annual tax as well as an administrative charge. Apparatus licensing for point-to-point services also involves detailed frequency coordination.

This framework serves to minimise interference between fixed service users and recovers economic revenue for the use of the public resource commensurate with spectrum denied to others.

An annual tax is applicable for each apparatus licence. The tax is based on several factors: the bandwidth access ($ per kHz), the spectrum location and the geographic location. Apparatus licences also attract an issue charge (to cover the cost of frequency assignment and administration), and a renewal charge in subsequent years. In the case of high capacity fixed links the issue charge could, based on the existing fee schedule, work out to several (tens of) thousands of dollars per link. However, the tax component for some apparatus licences is set at a fixed amount. Fixed annual fees apply for fixed point-to-point services in both the 5.8 GHz and 58 GHz bands.

The point-to-point (5.8 GHz band) licensing option authorises the operation of a pair of point-topoint stations one of two 20 MHz channels centred on 5.745 and 5.785 GHz. These apparatus licences are issued with a “no interference, no protection from interference” condition as the channels lie within a band designated for industrial, scientific and medical use. However, in the event of interference between the stations licensed by this option, normal licence data precedence applies. The annual licence fee under this option is currently $30.07 per link.

The point-to-point (58 GHz band) licensing option authorises the operation of fixed point-to-point links in the 57.2-58.2 GHz band. Detailed frequency coordination by ACMA is not required in this band. Apparatus licences are required to record device location. Licences in this band are endorsed with a condition of no interference/no protection with respect to other licensees in the band. The annual licence fee under this option is currently $180.00 per link.

Class licensing Radiocommunications devices authorised to operate under the Radiocommunications (Low Interference Potential Devices) LIPD Class License 2000 are typically low power transmitters providing short-range communications that do not require individual coordination for interference management purposes. In such a way, 60 GHz fixed point-to-point services may be operated under the LIPD class licence as date communication transmitters.

Devices operated under the LIPD class licence are not afforded protection from interference caused by other radiocommunications devices or services. In general, it is not expected that these millimetre wave high capacity links will suffer significant interference. However, an individual low interference potential device may experience, from other radiocommunications devices,


interference arising from the particular circumstances of the device’s operation. This has an impact on the reliability level for services.

Should interference occur, the onus is on the user of a low interference potential device to take measures to resolve that interference, for example, by re-tuning or ceasing to operate the device.

Class licences do not have to be applied for, and no licence fees are payable, but at the cost of a potentially lower level of service reliability.

Spectrum licensing Spectrum licences are a tradeable and technology-neutral spectrum access right for a fixed nonrenewable term. Instead of authorising the use of a specific device, spectrum licences authorise the use of spectrum space and give licensees the freedom to deploy any device from any site within their spectrum space, provided that the device is compatible with the core conditions of the licence and the technical framework for the bands.

Although fixed wireless services operate under a spectrum licence in the 3.425-3.4425 GHz and 3.475-3.4925 GHz bands, the deployment of the fixed point-to-point 70/80 GHz links under a spectrum licence option might significantly reduce spectrum efficiency as the potentially very high link capacity and spatially very high re-use factor would need to be subdivided into lots. The existing spectrum licence geographic grid is not well-suited to the short distances covered by these links. This restricts the potential gains of spectrum licensing through market trading. Additionally, the associated cost of the wide bandwidth utilisation under the spectrum licence may result in inefficient usage of the available spectrum.

In summary, the optimisation of interference management frameworks for microwave fixed services and high level of radio spectrum efficiency could not be achieved under spectrum licensing for the fixed point-to-point 70/80 GHz links, and hence this option is not recommended.


10. DISCUSSION AND RECOMMENDATIONS

10.1 DISCUSSION

The introduction of regulatory arrangements supporting the use of the 71-76 and 81-86 GHz bands would facilitate the use of a range of new high bandwidth short range services. However the use of traditional coordinated bandwidth based fee and licence structure would unnecessarily hinder deployment of these new services.

There are number of factors that have a bearing on potential licensing structures in the 71-76 and 81-86 GHz bands.

Utilisation of an antenna with very narrow beamwidth, with its inherent spectral efficiency and the ability to deploy links without the need for detailed frequency planning suggest that the traditional bandwidth based fee structure might not be appropriate for these bands.

The type of licence and access cost for these bands under the proposed management framework would be influenced by a number of factors:

• The nature of propagation in the millimetre wave bands and the possibility of employing highly directional “pencil beam” signal characteristics mean that applications can be implemented with minimal interference concerns, allowing a potentially highly efficient reuse of the spectrum. Thus, reducing co-ordination requirements.

• The availability of wide bandwidths supporting large capacity data rates, with sufficient bandwidth for terrestrial links to compete with or complement fibre optic based access networks.

• Operating path lengths of 1-3 km with high (>99.9%) availability.

• Availability of RADCOM database for the self-coordination purposes. The RADCOM database would hold and make available the relevant information required to enable licensees to plan and self-coordinate links in the 71-76 and 81-86 GHz bands. The RADCOM database would also serve as the reference point for the data and time a link is registered, thereby establishing the time priority of links. Further issues associated with the RADCOM database implementation for the purposes of the 71-76 and 81-86 GHz band link registration might require further investigation.

• The degree to which the ACMA would become involved in any interference mediation.


10.2 RECOMMENDATIONS

1. The 71-76 and 81-86 GHz bands should be opened for the point-to-point fixed service in Australia with no explicit channel plan, but with 125 MHz guard band at the top and bottom of each 5 GHz band.

2. A licensing framework based on a link registration system should be adopted recognising the value and high spectrum reuse potential of the bands.

3. The RADCOM database should be the basis for the registration system.

4. To encourage commercial development and efficient use of the 71-76 and 81-86 GHz bands, a fixed fee approach, similar to that applied for 58 GHz point-to-point links, should be adopted for the licence fee determination.

5. To avoid spectrum hoarding made possible by the low fee structure, a rollout obligation should be attached to licences and a 12 month time limit for achieving the rollout goal might be proposed. A similar arrangement was implemented for apparatus licences intended for broadband wireless access in the 1900-1920 MHz and 2010-2025 MHz bands [24]. The FCC recommended a similar arrangement based on a construction period of 12 months, commencing on the date of link registration, for fixed point-to-point 71-76 and 8186 GHz band wireless links [7].


REFERENCES

[1] ITU-R P.676-6, “Attenuation by Atmospheric Gases”, 2005.

[2] ITU-R P.838-3, “Specific Attenuation model for Rain for Use in Prediction Methods”, 2005.

[3] ITU-R P.840-3, “Attenuation Due to Clouds and Fog”, 1999.

[4] CCIR Report 236-2, Foliage loss

[5] ITU-R P-837-4, “Characteristics of Precipitation for Propagation Modelling” 2003.

[6] ELVA-Link, “PPC Series Wireless Series Link”, May 2004.

[7] FCC 03-248, “Allocation and Service Rules for the 71-76GHz, 81-86GHz and 92-95GHz Bands”, federal Communication Commission, Nov. 2003.

[8] DGTP-001-05,”Consultation on a renewed spectrum Policy Framework for Canada and Continued Advancement in Spectrum Managements”, Sep. 2005.

[9] CEPT/ECC/REC (05) 07: “Radio frequency channel arrangements for fixed Services Systems operating in the bands 71-76 GHz and 81-86 GHz”, Oct. 2005.

[10] ETSI TS 102 524 v1.1.1 “Fixed Radio Systems; radio equipment and antennas for use in Point-to-Point Millimetre wave applications in the Fixed Services (mmwFS) frequency bands 71 GHz to 76 GHz and 81 GHz to 86 GHz”, July 2006.

[11] Ofcom “Making Spectrum Available for the 71-78 GHz and 81-86 GHz Bands”, Nov. 2006.

[12] ITU-R RA.314-10, “Preferred frequency bands for radio astronomical measurements ”, 2003.

[13] “Australian radiofrequency spectrum plan”, Australian Communication Authority, Jan. 2005.

[14] ACMA, Radiocommunications Licence Conditions (Amateur Licence) Determination No. 1 of 1997, http://www.acma.gov.au/acmainterwr/aca_home/legislation/radcomm/acts/consolidations/r adam_1of97.pdf

[15] WCA-PCG-7080-1, “Path Coordination Guide for the 71-76 and 81-86 GHz Millimetre Wave Bands”, WCA+60 Committee, version 1.0, June 2004

[16] Crane, Robert K., “Electromagnetic Wave Propagation through Rain” Wiley Interscience, 1996.

[17] ITU-R RA-769-1, “Protection Criteria used for Radioastronomical measurements”, 1995.

[18] RALI MS 31 ACMA, “Notification zones for Apparatus Licensed Services around Radio Astronomy Facilities”, Aug. 2006.

[19] ITU-R RA-1031-1, “Protection of the radioastronomy service in frequency bands shared with other services”, 1995.


[20] Vehicle Radar System (47 C.F.R. Section 15.253), FCC REPORT AND ORDER December 15, 1995.

[21] ETSI EN 302 091-1 v1.3.3, “”Part 1: Technical characteristics and test methods for radar equipment operating in the 76 GHz to 77 GHz range, May 2006.

[22] AS/NZS 4268:2003, “Radio equipment and system – Short range devices – Limits and methods of measurements”, Australian/ New Zealand Standard, Dec. 2003.

[23] Allocations and Service Rules for the 71-76 GHz, 81-86 GHz, and 92-95 GHz Bands and Loea Communications Corporation Petition for Rulemaking, Notice of Proposed Rulemaking (NPRM), FCC 02-180, 67 Fed. Reg. 59036 (2002).

[24] RALI FX 19, “Frequency Coordination and Licensing procedures for apparatus licensed Broadband Wireless Access services in 1900-1920 and 2010-2025 MHz bands”, Apr. 2005.

[25] The ECC decisions ECC/DEC(04)10 (24 GHz SRR) and ECC/DEC(04)03 (79 GHz SRR) are available in the Internet: ERO-homepage


Documents

Planning 71-76-81-86 Ghz Bands Millimetre