RADIO FREQUENCY CHANNEL ARRANGEMENTS FOR FIXED SERVICE SYSTEMS OPERATING IN THE BANDS 71-76 GHz AND 81 - 86 GHz

Recommendation approved by the Working Group "Spectrum Engineering" (WGSE)

INTRODUCTION

The millimetre wave spectrum above 70 GHz is of increasing interest to service providers and systems designers because of the wide bandwidth available for carrying communications at this frequency range. These wide bandwidths are valuable in supporting applications such as extremely-high-speed data transmission. Because of the unique nature of the propagation in the millimetre bands and possibility to employ highly directional (pencil-sized) beams, multiple services and applications can be implemented without interference concerns, thus ensuring highly efficient re-use of the frequency band.

The use of the 71-76 GHz and/or 81 -86 GHz bands provides an inviting opportunity to cope with the future market demands for increasingly high bandwidth access, in particular for Internet-bases applications. Fixed radio links may be deployed much quicker and in certain cases are more cost efficient than the wired networks, and as such the millimetre waves provide sufficient bandwidth for terrestrial fixed links to compete or complement the fiber optic based access networks. The competing FSO (Free space optics) systems are also emerging as a possible solution that on short distances can support broadband capabilities (1-10 Gbit/s) with reasonable availability and reliability.

In the proposed scenario of using the 71 - 76 GHz and/or 81 - 86 GHz band for fixed services, it appears possible to implement very high capacity (up to 10 Gbit/s) links with some 1-2 km hop lengths (line-of-sight conditions); these systems would allow a rapid and effective deployment of broadband capacity in areas where fibre optic cables are not available or are not cost-effective.

The main features of operating fixed radio systems in this region of spectrum may be summed up as follows:

• Availability of wide bandwidths, allowing for the low cost of traffic in terms of bit/sec/Hertz/Euro;

• Possibility of multiple channel frequency re-use, thanks to the unique propagation conditions, highly directional pencil-sized beams; this will also enable implementation of multiple services and applications without interference concerns, obviating the need for coordination;

• Radio links are much easier to install comparing to alternative wire-bound solutions like fiber optical links;

• Ability to ensure high security because of low possibility of interference/capture of signals.

Use of the spectrum above 70 GHz is the only viable solution for fixed links to achieve the above objectives. The lower FS band at around 52 GHz (28/56 MHz channels) has similar propagation conditions but does not provide sufficient space for truly wide band links.

Therefore the bands 71 - 76 GHz and 81 - 86 GHz may be considered suitable for high speed data FS links.

It should be noted that the bands 71 - 76 GHz and 81 - 86 GHz are used in some countries by other services or applications than FS civil links. In particular the bands 71-74 GHz and 81 - 84 GHz have been identified as NATO Type 3 bands, i.e. for possible military use in NATO Europe. This should be taken into account by administrations wishing to use whole or parts of the frequency bands 71 - 76 GHz and/or 81 - 86 GHz for civil FS links.

RADIO-FREQUENCY CHANNEL ARRANGEMENTS IN THE BAND 71 - 76 GHz

Let fr be the reference frequency of 71000 MHz, n be the centre frequency of a radio-frequency channel in the band 71 - 76 GHz, n be the channel number,

then the centre frequencies of individual channels with 250 MHz separation are expressed by the following relationship:

fn = fr + 250·n MHz

where: n = 1, 2, 3, ..., 19

Note, that the specified channels may be used to form either TDD or FDD systems within the single band, or in combination with other band specified in this recommendation.

Calculated parameters according to ITU-R Rec. 746

TABLE A1.1

XS Separation between centre frequencies of adjacent channels Z1S Separation between the lower band edge and the centre frequency of the first channel Z2S Separation between centre frequencies of the final channel and the upper band edge

RADIO-FREQUENCY CHANNEL ARRANGEMENTS IN THE BAND 81 - 86 GHz

Let fr be the reference frequency of 81000 MHz, n be the centre frequency of a radio-frequency channel in the band 81 - 86 GHz, n be the channel number,

then the centre frequencies of individual channels with 250 MHz separation are expressed by the following relationship:

fn = fr + 250·n MHz

where: n = 1, 2, 3, ..., 19

Note, that the specified channels may be used to form either TDD or FDD systems within the single band, or in combination with other band specified in this recommendation.

Calculated parameters according to ITU-R Rec. 746

TABLE A2.1

XS Separation between centre frequencies of adjacent channels Z1S Separation between the lower band edge and the centre frequency of the first channel Z2S Separation between centre frequencies of the final channel and the upper band edge

EXAMPLES OF PAIRING AND AGGREGATING CHANNELS IN FREQUENCY BANDS 71 -76 / 81 - 86 GHz

The principle of using the channels from within the bands 71 - 76 GHz and 81 - 86 GHz in a single duplex FDD arrangement is described in the Fig. A3.1.

Fig. A3.1. Combining the channels from 71 - 76 / 81 - 86 GHz bands into a single FDD arrangement with duplex separation of 10 GHz

The principle of duplex channels within a single band 71 - 76 GHz or 81 - 86 GHz with duplex separation of less than 5 GHz is shown in Fig. A3.2.

Fig. A3.2. Combining the channels from single 71 -76 GHz or 81 - 86 GHz band into an FDD arrangement with duplex separation of less than 5 GHz

When the wider channels are needed, e.g. for very high bitrate and high system gain applications (e.g. employing FSK modulation), then a flexible number of consecutive 250 MHz channels may be aggregated into FDD channels, as illustrated in Fig. A3.3 for duplex separation of 10 GHz or in Fig. A3.4 for duplex separation of less than 5 GHz.

Figure A3.3: Example of aggregating multiple 250 MHz channels, possibly alongside with original 250 MHz wide channels

Figure A3.4: Example of aggregating multiple 250 MHz channels, possibly alongside with original 250 MHz wide channels within the single band 71 - 76 or 81 - 86 GHz

ECC/REC/(05)07

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PRELIMINARY EXAMPLES OF FS TECHNICAL PARAMETERS CONSIDERED IN FREQUENCY BANDS 71 - 76 / 81 - 86 GHz

This annex provides examples of the key FS radio system parameters, which may be used by administrations as a guidance for interference evaluation and calculations for frequency sharing with other services in frequency bands 71 - 76 GHz and 81 - 86 GHz. These parameters should not be understood as regulatory limits.

The following tables set out the basic parameters for FS system, suited to transmit 1Gbit/s payload but exploiting different number of 250 MHz channels in 71 - 76 GHz frequency band and/or in 81 - 86 GHz frequency band, according to the arrangements given in Annexes 1-3 of this recommendation.

Table A4.1: Parameters for 1Gb/s FS link using one 250 MHz channel

Table A4.2: Parameters for 1Gb/s FS link using two aggregated 250 MHz channels

Table A4.3: Parameters for 1Gb/s FS link using five aggregated 250 MHz channels