Technical Frequency Assignment Criteria
Fixed Point-to-Point Radio Services with Digital Modulation Operating in the Frequency Range 55.78 to 57 GHz
Version 1.0 (June 2003)
|
|
Technical Frequency Assignment CriteriaFixed Point-to-Point Radio Services with Digital Modulation Operating in the Frequency Range 55.78 to 57 GHz Version 1.0 (June 2003) |
RA
408 is also available as a 
PDF File (155KB)
Foreword
It is required by the Wireless Telegraphy Acts, 1949 and 1998 that no radio apparatus shall be installed or used in the United Kingdom, except under the authority of a licence granted by the Secretary of State. It is a condition of such a licence that the performance of the radio equipment meets certain minimum standards laid down in the UK Radio Interface Requirement 2000 (UK RIR 2000). Compliance will have been notified in accordance with the R&TTE (Radio Equipment and Telecommunications Terminal Equipment) Directive.
This document details the frequency assignment criteria and principles that will be employed by Radiocommunications Agency (RA) in the selection of frequencies for use by compliant fixed terrestrial (point-to-point) digital radio equipment operating in the band or frequency range specified.
These assignment criteria are subject to updating and amendment, and intending operators/manufacturers should consult the latest version of this document complete with any amendments. Single copies of this document are available free from the RA library at the address below:
Radiocommunications
Agency
Library Services
Wyndham House
189 Marsh Wall
London E14 9SX.
Switchboard
and 24 hour enquiry service:
Telephone: 020 7211 0211
Library
and Publicity:
Telephone: 020 7211 0502/0505
Fax: 020 7211 0507
This document outlines the frequency assignment criteria and principles that will be employed by RA in the selection of frequencies for use by fixed terrestrial (point-to-point) digital radio services operating in the frequency range 55.78 to 57.0 GHz.
The channel plan shall be in accordance with that given in Section 5.
This document takes account of the equipment standard EN 300 407 V1.3.1. RA will currently license the following classes of equipment:
| Class 2 – | equipment performances
based on typically 4-state modulation schemes (e.g.: 4-FSK, 4-PSK or equivalent); |
|
Class 3 – |
equipment performances
based on typically 8-state modulation schemes (e.g.: 8-PSK or equivalent); |
|
Class 4 – |
equipment performance
based on typically 16 or 32-state modulation schemes |
The Foreword of this document states that the establishment, use or installation of transmitting or receiving apparatus is subject to the issue of a licence by the Secretary of State. The licensee must ensure that equipment conforms with and is maintained to the standards referenced in UK RIR 2000.
Minimum link length policy does not apply to links operating in the 55 GHz band.
2. Transmitting and Receiving Installations
The transmitting and receiving installations shall conform to Sections 2.2 and 2.3 below. The installations shall be implemented in accordance with good engineering practice.
The antenna installation at the licensed premises shall be such that the antenna pattern will not exceed the CO-polar and cross-polar Radiation Pattern Envelopes (RPEs) given in UK RIR 2000 with the zero degree datum being the boresight path between the two stations.
The allocated plane of polarisation of emissions for radio links in this frequency band will be vertical. Operators who elect to use horizontal polarisation must inform and obtain approval from the RA assignment engineer.
The antenna alignment surface shall be aligned as precisely as possible. Misalignment shall be no greater than 3°.
2.4 Equivalent Isotropically Radiated Power (EIRP)
The assigned value of EIRP will be stated in the licence and must not be exceeded although a tolerance of ±3 dB on this assigned value will be allowed in practice. Under no circumstance is the EIRP to exceed 30 dBW.
3. Principles of Assignment and EIRP Derivation
A normal frequency assignment for a single or multi-section bi-directional link shall comprise a pair of radio frequencies of corresponding channel number; one from each of the low and high frequency groups.
3.1.1 Normal Assignment Flow Diagram
Annex C shows a flow diagram for the normal assignment process.
In the case of a multi-section link the direction of transmission of the two frequencies shall alternate for successive repeater sections so that the transmitter frequency assigned to any station shall be taken from only one of the frequency groups in the lower or upper half of the band.
The frequency difference between a pair of corresponding go and return frequencies in the 55.78 to 57 GHz band shall be 616 MHz.
3.4 Parallel Links Operating over the Same Path
In assessing the interference potential between parallel links operating over the same path, it is assumed that the wanted and interfering signals suffer correlated fading. Therefore, protection from interference is derived from frequency separation and cross-polar discrimination (if any). To be classed as operating over the same path, the stations located at the sites at each end of the links must be within 10 m of each other in the horizontal plane and within 2 m in the vertical plane.
Table 1 lists the minimum frequency separations for like systems operating under these conditions. For mixed capacity systems, the appropriate minimum separations are derived by the sum of half of the individual minimum separations given. The assignment software identifies available channels that meet the minimum frequency separation criteria, in accordance with the channel plan defined in Section 5.
|
Spectrum Efficiency Class |
Minimum
Capacity (Mbit/s)
|
Minimum
separation between carriers on a parallel route operating over the same
path (MHz)
|
|
2
|
2
|
3.5
|
|
2
|
2
x 2
|
3.5
|
|
2
|
8
|
7
|
|
2
|
2
x 8
|
14
|
|
2
|
34
|
28
|
|
3
|
51
|
28
|
|
4
|
8
|
3.5
|
|
4
|
2
x 8
|
7
|
|
4
|
34
|
14
|
|
4
|
51
|
14
|
|
4
|
140/155
|
56
|
|
Table
1: Frequency Separations
|
In assigning frequencies for links which are in the same geographical area, due consideration shall be taken of the antenna discrimination. When available, data derived from a manufacturer’s guaranteed RPE will be used. Otherwise the appropriate RPE, specified in UK RIR 2000, will be assumed.
RA will normally assume that each hop has a clearance from obstructions of not less than 0.577F between the transmitting and receiving antennas, at the two stations, under conditions corresponding to values of the ratio K greater than 0.7.
F : First Fresnel Zone Clearance
K : Ratio of effective earth radius to real earth radius
Obstructed paths will be allowed where their need is clearly demonstrated, with an EIRP increased up to a maximum of 6 dB above the normal assignment level providing that the maximum limit of 30 dBW is not exceeded. Above this level operators will be expected to accept the possibility of lower link availability. The following conditions will apply:
a) the higher power needed for this operation does not unnecessarily sterilise the surrounding area and block further normal assignments;
b) the increase in EIRP will only be allowed if the obstruction cannot be overcome by increasing the antenna height;
c) higher performance antennas (if available) should be used to minimise the sterilisation of surrounding areas, considering the higher than normal EIRP associated with this type of operation;
d) the increased EIRP will only be allowed on link availabilities 99.90% and 99.99%.
Details of the assignment process modifications to deal with operation over an obstructed path are given in Annex E.
The median path loss between two stations is equal to the free-space-path-loss (FSPL) plus the atmospheric gaseous absorption:
| FSPL = 92.45 + 20log(d) + 20log(f) | |
| Median path loss (dB) = FSPL + gaseous absorption. | |
| where: | d = distance between the stations in km; |
| f = frequency of operation in GHz; | |
| gaseous absorption – see Section 3.7.2. |
The link budget shall include contributions from gaseous absorption in addition to the basic FSPL. Gaseous absorption is based on oxygen and water vapour data obtained from ITU-R Rec. P.676-4. Since there is a large variation in gaseous absorption values in this band, these values shall be calculated at the centre frequency of the channel under consideration and based on ground level air temperature of 15°C and water vapour density of 10g/m3 (See ITU-R Rec. P.836-1, Figure 4).
Availabilities greater that 99.99% are to be agreed with RA on a case-by-case basis.
NOTE: Throughout this document, availability will be taken to mean propagation availability.
|
Spectrum
Efficiency Class
|
Capacity
(Mbit/s) in
Bandwidth (MHz) |
Receiver
Median Signal Level
|
||||||||
|
2
|
2
in 3.5
|
-110
dBW + M
|
||||||||
|
2
|
2
x 2 in 3.5
|
-107
dBW + M
|
||||||||
|
2
|
8
in 7
|
-104
dBW + M
|
||||||||
|
2
|
2
x 8 in 14
|
-101
dBW + M
|
||||||||
|
2
|
34
in 28
|
-98
dBW + M
|
||||||||
|
3
|
51
in 28
|
-95
dBW + M
|
||||||||
|
4
|
8
in 3.5
|
-100
dBW + M
|
||||||||
|
4
|
2
x 8 in 7
|
-97
dBW + M
|
||||||||
|
4
|
34
in 14
|
-94
dBW + M
|
||||||||
|
4
|
51
in 14
|
-93
dBW + M
|
||||||||
|
4
|
140/155
in 56
|
-90
dBW + M
|
||||||||
|
||||||||||
|
Table
2: Receiver Median Signal Levels
|
RA will in general examine applications for the use of radio links on the assumption that the median signal level of the receiver input is detailed as per Table 2. A transmitter power shall be assigned accordingly.
The figures in Table 2 are derived using the methodology shown in Annex A.
Fade margins are calculated according to Recommendation ITU-R P.530-7 §2.3 and §2.4 for clear-air and hydrometeor (rain) fading respectively. Note that the Recommendation refers to clear-air fading as due to “multipath and related factors”; the more general term “clear-air” is used here.
Fade margin is calculated by apportioning the overall permissible unavailability between clear-air and rain fading. The assignment software utilises the equations for clear-air and rain fading given in P.530-7 §2.3 and §2.4 respectively to iterate for the value of fade for which the sum of the individual (clear-air and rain) unavailabilities equals the required overall unavailability. It is assumed that rain and total atmospheric fades are unlikely to occur simultaneously. For cases where the ratio of outage times for rain and clear-air exceeds 40 only the dominant method is calculated.
The fade margin required for clear-air effects depends on frequency, path length, radio-climatic factors and the service availability required. The fade exceeded for a given percentage of an average year is calculated according to Recommendation ITU-R P.530-7 §2.3.
The rain fade margin for a given availability depends on the path length, frequency, polarisation and geographic location. UK rain rates exceeded for 0.01% of an average year are shown in Annex F at the centre of each 100-km grid square. This rain-rate data is obtained from UK meteorological records.
The rain fade is derived as follows:
mm/hr, is used to calculate the fade.
,
for the rain intensity, ,
of interest is calculated for the required frequency and polarisation using
equation 1 of ITU-R Rec. P.838-1:
Values of the regression
coefficients, 
and
, are given in Table 3 below for both
horizontal (H) and vertical (V) polarisations. These have been
derived by interpolation between the values in Table 1 of ITU-R Rec. P.838-1,
for the highest frequency in the band:
|
Frequency
|
 |
 |
 |
 |
|
57
GHz
|
0.654
|
0.591
|
0.839
|
0.836
|
|
Table
3. Regression Coefficients
|
The path reduction
term, 
,
is given in ITU-R Rec. P.530-7 as:
 |
|
| where: |  |
The effective path
length,
, is found
by multiplying the actual physical path length, 
,
by the reduction term, ,
found above.
The path attenuation exceeded for 0.01% of time is given by equation 37 of ITU-R Rec. P.530-7:
|
|
| where: |  |
The attenuation,
,
exceeded for other time percentages, 
,
(over the range 0.001% to 1%) may be deduced from equation 38 of ITU-R Rec.
P.530-7:
Links whose calculated fade is less than 10 dB will be allocated a fade margin of 10 dB.
3.11 Equivalent Isotroically Radiated Power Calculation
The licence schedule will detail the assigned EIRP for each transmitting station. This is based on the following calculation:
EIRP = Rx median signal level + Rx station losses - Rx antenna gain + path loss
Where the Rx (Receiver) median signal level is defined in Table 2. The maximum CO-polar gain figure for the receiving antenna is used.
The link to be assigned is co-ordinated with all other links in the same frequency band within a co-ordination zone radius of 70 km around each site. The size of the co-ordination zone may be reviewed from time to time as operational experience is gathered. Interference to and from the proposed link is assessed taking into account the path profile between the two stations. Use is made of antenna radiation patterns to obtain the gain of antennas in the direction of unwanted signals.
The two conditions considered in the evaluation of interference from each single-entry interference source are:
a) the median unwanted signal must be at least equal to the wanted to unwanted (W/U) ratio below the faded wanted signal;
b) the enhanced unwanted signal must be at least equal to the W/U below the median wanted signal.
If either of the above two conditions are not met and an alternative frequency cannot be ascertained then the link will not be assigned.
The procedures followed are in line with ITU-R Rec. P452-7 and outlined in the flow diagram shown in Annex D.
The interference limits are derived as follows:
Interference limit = Receiver Sensitivity Level (RSL) for a Bit Error Rate (BER) of 10-6 - W/U ratio.
4.3 CO and Adjacent Channel Limits
The maximum CO-channel and adjacent channel interference limits, at the receiver input, from a single unwanted source are shown in Tables 4 and 5. W/U ratios for single-entry interferers relating to mixed capacity digital systems are shown in the matrices in Annex B.
The adjacent channel interference limits given in Table 5 do not apply to links operating on a parallel path over the same hop. Under these circumstances fading is assumed correlated with interference protection offered by frequency discrimination.
|
Spectrum
Efficiency Class
|
Capacity
(Mbit/s) in Bandwidth (MHz)
|
W/U Ratio
(dB)
|
Interference
Limit (dBW)
|
|
2
|
2
in 3.5
|
27
|
-137
|
|
2
|
2
x 2 in 3.5
|
27
|
-134
|
|
2
|
8
in 7
|
27
|
-131
|
|
2
|
2
x 8 in 14
|
27
|
-128
|
|
2
|
34
in 28
|
27
|
-125 |
|
3
|
51
in 28
|
34
|
-129
|
|
4
|
8
in 3.5
|
34
|
-134
|
|
4
|
2
x 8 in 7
|
34
|
-131
|
|
4
|
34
in 14
|
34
|
-128
|
|
4
|
51
in 14
|
34
|
-127
|
|
4
|
140/155
in 56
|
34
|
-
124
|
|
Table
4: Single Entry CO-Channel Interference Limits
|
|
Spectrum
Efficiency Class
|
Capacity
(Mbit/s) in Bandwidth (MHz)
|
W/U Ratio
(dB)
|
Interference
Limit (dBW)
|
|
2
|
2
in 3.5
|
3
|
-113
|
|
2
|
2
x 2 in 3.5
|
6
|
-113
|
|
2
|
8
in 7
|
6
|
-110
|
|
2
|
2
x 8 in 14
|
6
|
-107
|
|
2
|
34
in 28
|
6
|
-104
|
|
3
|
51
in 28
|
5
|
-100
|
|
4
|
8
in 3.5
|
5
|
-105
|
|
4
|
2
x 8 in 7
|
5
|
-102
|
|
4
|
34
in 14
|
5
|
-99
|
|
4
|
51
in 14
|
5
|
-98
|
|
4
|
140/155
in 56
|
5
|
-
95.5
|
|
Table
5: Single Entry Adjacent Channel Interference Limits
|
Multiple Interferers
In Tables 4 and 5, as well as in Annex B, the single-entry digital W/U ratios include allowances for multiple interferers. The allowances are 4 dB for CO-channel interferers and 6 dB for adjacent channel interferers independent of bit-rate.
5.1 Derivation of Radio Frequency Channels for the Band 55.78 to 57.0 GHz
The channel arrangements based on a 14 MHz raster and extracted from CEPT Recommendation T/R 12-12 are as shown below:
| Let: | fo be the reference frequency of 55.814 GHz for the 55.78 to 57 GHz band. | ||
| fn be the centre frequency of the radio-frequency channel in the lower half of the band. | |||
| f'n be the centre frequency of the radio-frequency channel in the upper half of the band. | |||
| Tx/Rx separation | = 616 MHz | ||
| Separation band | = 112 MHz | ||
|
Individual channel frequencies are expressed by the following relationships with FO and fn in MHz: |
|||
|
a)
|
For systems with a carrier spacing of 56 MHz: | ||
| Lower half of the band: | fn = (FO + 56n) MHz | ||
| Upper half of the band: | f'n = (FO + 616 + 56n) MHz | where n = 1,2,3,...9 | |
|
b)
|
For systems with a carrier spacing of 28 MHz: | ||
| Lower half of the band: | fn = (FO + 14 + 28n) MHz | ||
| Upper half of the band: | f'n = (FO + 630 + 28n) MHz | where n = 1,2,3,...18 | |
|
c)
|
For systems with a carrier spacing of 14 MHz: | ||
| Lower half of the band: | fn = (FO + 21 + 14n) MHz | ||
| Upper half of the band: | f'n = (FO + 637 + 14n) MHz | where n = 1,2,3,... 36 | |
|
d)
|
For systems with a carrier spacing of 7 MHz: | ||
| Lower half of the band: | fn = (FO + 24.5 + 7n) MHz | ||
| Upper half of the band: | f'n = (FO + 640.5 + 7n) MHz | where n = 1,2,3,...72 | |
|
e)
|
For systems with a carrier spacing of 3.5 MHz: | ||
| Lower half of the band: | fn = (FO + 26.25 + 3.5n) MHz | ||
| Upper half of the band: | f'n = (FO + 642.25 + 3.5n) MHz | where n = 1,2,3,...144 | |
Annex A: Receiver Input Levels and Interference Levels
Tables A.1 to A.3 give examples of receiver input levels and maximum permitted interference levels for digital systems operating in the frequency band 55.78 to 57.0 GHz.
|
Channel
Bandwidth (MHz)
|
3.5
|
3.5
|
7
|
14
|
28
|
||||||||
|
Minimum
Bit Rate (Mbit/s)
|
2
|
2
x 2
|
8
|
2
x 8
|
34
|
||||||||
|
Assumed
Modulation
|
4-PSK
|
4-PSK
|
4-PSK
|
4-PSK
|
4-PSK
|
||||||||
|
Thermal
Noise KT (dBW/Hz)
|
-204
|
-204
|
-204
|
-204
|
-204
|
||||||||
|
Receiver
Bandwidth B (dBHz)
|
60.5
|
63.5
|
66.5
|
69.5
|
72.5
|
||||||||
|
Receiver
Noise KTB (dBW)
|
-143.5
|
-140.5
|
-137.5
|
-134.5
|
-131.5
|
||||||||
|
Noise
Figure (dB) (NOTE 3)
|
13
|
13
|
13
|
13
|
13
|
||||||||
|
S/N
for BER = 10-6 without
Coding Gain (dB) (NOTE 4) |
13.5
|
13.5
|
13.5
|
13.5
|
13.5
|
||||||||
|
S/N
for BER = 10-6 with Coding Gain (dB) (NOTE 4)
|
-
|
-
|
-
|
-
|
-
|
||||||||
|
Fixed
System Losses (dB)
(NOTE 2) |
6
|
6
|
6
|
6
|
6
|
||||||||
|
Interference
Margin (dB)
|
1
|
1
|
1
|
1
|
1
|
||||||||
|
Receiver
Sensitivity Level for BER = 10-6 (dBW)
|
-110
|
-107
|
-104
|
-101
|
-98
|
||||||||
|
Median
Receiver Input Level (dBW) (NOTE 1)
|
-110+ M
|
-107+ M
|
-104+ M
|
-101+ M
|
-98+ M
|
||||||||
|
Planned
CO-Channel Interference Limit (dBW)
|
-137
|
-134
|
-131
|
-128
|
-125
|
||||||||
|
|||||||||||||
|
Table
A.1: Example Noise Budget and Interference Calculations for Class
2 Digital System
|
|
Channel
Bandwidth (MHz)
|
7
|
3.5
|
28
|
||||||||
|
Minimum
Bit Rate (Mbit/s)
|
2
x 8
|
8
|
51
|
||||||||
|
Assumed
Modulation
|
16-QAM
|
16-QAM
|
8-PSK
|
||||||||
|
Thermal
Noise KT (dBW/Hz)
|
-204
|
-204
|
-204
|
||||||||
|
Receiver
Bandwidth B (dBHz)
|
66.5
|
63.5
|
70.2
|
||||||||
|
Receiver
Noise KTB (dBW)
|
-137.5
|
-140.5
|
-133.8
|
||||||||
|
Noise
Figure (dB) (NOTE 3)
|
13
|
13
|
13
|
||||||||
|
S/N
for BER = 10-6 without Coding Gain (dB) (NOTE 4)
|
20.5
|
20.5
|
18.8
|
||||||||
|
S/N
for BER = 10-6 with Coding Gain (dB)(NOTE 4)
|
-
|
-
|
-
|
||||||||
|
Fixed
System Losses (dB)
(NOTE 2) |
6
|
6
|
6
|
||||||||
|
Interference
Margin (dB)
|
1
|
1
|
1
|
||||||||
|
Receiver
Sensitivity Level for
BER = 10-6 (dBW) |
-97
|
-100
|
-95
|
||||||||
|
Median
Receiver Input Level (dBW)
(NOTE 1) |
-97 + M
|
-100 + M
|
-95 + M
|
||||||||
|
Planned
CO-Channel
Interference Limit (dBW) |
-124
|
-127
|
-122
|
||||||||
|
|||||||||||
|
Table
A.2: Example Noise Budget and Interference Calculations for Classes
3 and 4
Digital Systems |
|
Channel
Bandwidth (MHz)
|
14
|
14
|
56
|
||||||||
|
Minimum
Bit Rate (Mbit/s)
|
34
|
51
|
140/155
|
||||||||
|
Assumed
Modulation
|
16-QAM
|
16-QAM
|
16-QAM
|
||||||||
|
Thermal
Noise KT (dBW/Hz)
|
-204
|
-204
|
-204
|
||||||||
|
Receiver
Bandwidth B (dBHz)
|
69.5
|
71.5
|
77.4
|
||||||||
|
Receiver
Noise KTB (dBW)
|
-134.5
|
-132.5
|
-126.6
|
||||||||
|
Noise
Figure (dB) (NOTE 3)
|
13
|
12
|
12
|
||||||||
|
S/N
for BER = 10-6 without Coding Gain (dB) (NOTE 4)
|
20.5
|
20.5
|
-
|
||||||||
|
S/N
for BER = 10-6 with Coding Gain (dB) (NOTE 4)
|
-
|
-
|
17.6
|
||||||||
|
Fixed
System Losses (dB) (NOTE 2)
|
6
|
6
|
6
|
||||||||
|
Interference
Margin (dB)
|
1
|
1
|
1
|
||||||||
|
Receiver
Sensitivity Level for BER = 10-6 (dBW)
|
-94
|
-93
|
-90
|
||||||||
|
Median
Receiver Input Level (dBW) (NOTE 1)
|
-94 + M
|
-93 + M
|
-90 + M
|
||||||||
|
Planned
CO-Channel Interference Limit (dBW)
|
-121
|
-120
|
-117
|
||||||||
|
|||||||||||
|
Table
A.3: Example Noise Budget and Interference Calculations for Class
4 Digital Systems
|
Annex B: Wanted to Unwanted Levels
Tables B1 to B11 give the W/U ratios for all licensable channel bandwidths up to three times and, in a minority of cases, beyond three times the mean value of the sum of the wanted and unwanted channel spacing.
The figures in Tables B1 to B11 have been derived on the following basis:
CO-channel and adjacent channel W/U ratios for like with like systems have been linked to Tables 4 and 5 and therefore to the appropriate equipment standard. W/U ratios for all other combinations have been derived using RA's Net Filter Discrimination (NFD) spreadsheet. However, where the established W/U ratios, defined in earlier assignment criteria, are lower than those obtained using the filter discrimination methodology, those values have been retained.
Important Note:
When the wanted and unwanted channels of digital systems are not equal, Step 1 in the W/U tables is equal to 1/2 the narrowest bandwidth. Thereafter the step sizes are equivalent to the narrowest bandwidth. When the wanted and unwanted channels are the same size, all step sizes are equal to the channel width of these systems. Shaded steps indicate a W/U ratio of -40 dB.
Click [here] to view Tables B1 to B11
Annex C: Normal Assignment Process – Flow Diagram
Click [here] to view Flow Diagram
Annex D: High-Level Flow Diagram for Recommendation ITU-R P.452
Click [here] to view Flow Diagram
Annex E: UK Rain Rates in mm/hr for 99.99% Availability by National Grid Square
Click [here] to view
|
|
|
|
|
|
|
|
|
|
|
|
| RA
408 June 2003 |
 |