Date:
Meeting:
8th May 2002
PPWG
Document Reference:
Paper No:
533572014
PPWG (02-02)/027
Future Use of 18 GHz Band
Author: Peter Gibson, Stratex Networks
Introduction
The 18 GHz band (17.7 – 19.7 GHz) is currently administered exclusively by BT with this
arrangement due to cease from August 2003. The RA will assume total management and
frequency assignment from that date. The band has an ITU allocation of co-primary
between fixed terrestrial and satellite. The diagram kindly provided by BT at the Sept 01
FLCC meeting has been reproduced for reference (next page).
In addition to the other shared services there are at least three different channel
arrangements deployed for terrestrial P-P services in the 18 GHz band. Based on the BT
diagram there are currently two plans used, one for low capacity systems with a T/R split
of 1008 MHz although this is to be confirmed. The other band plan uses the conventional
T/R split of 1010 MHz and is specifically for systems operating with a bandwidth of 27.5/55
MHz. The other low capacity band plan would appear to be obsolete and will contain
legacy links (number to be confirmed by BT) using channel bandwidth of 10/20 MHz.
Future Plans
Work needs to start now on the transitional arrangements for the hand over of the 18 GHz
band. This will involve bi-lateral meetings between BT and RA where more commercially
sensitive information would be discussed. However there also needs to be a general
Industry forum to discuss the future arrangements of the 18 GHz band for P-P terrestrial
services. These discussions should take place simultaneously with the BT/RA bi-lateral
discussions. The aim of both activities is to ensure a smooth transition from BT exclusive
to RA managed with a target date for RA frequency assignments of August 2003. Lessons
can be learned from the take back of the 15 GHz band where the RA announced its use by
January 2002, to date the 15 GHz band is still unavailable. The 18 GHz should not suffer a
similar delay.
The use of two band plans may need further investigation. To initiate discussion the
following issues are raised.
Does it make sense to continue to operate/promote low capacity systems in the 18 GHz
band?
Two factors to consider are, link lengths are reducing in mobile networks and in general
capacities are increasing for both customer access and mobile infrastructure. Other
frequency bands such as 13/15 GHz and 23 GHz and above can support the low capacity
needs of future requirements.
Should the 18 GHz band support lower efficient modulation systems such as 4 state for
PDH and 16 state for SDH?
If the decision is taken to support only the 13.75/27.5/55 MHz bandwidths that are
currently standardised in the relevant ETSI standards then is it also appropriate to restrict
the future use of the band to more spectrally efficient technology?
Date:
Meeting:
8th May 2002
PPWG
Document Reference:
Paper No:
533572014
PPWG (02-02)/027
Proposal
Important decisions need to be taken for the future use of the 18 GHz band. The current
use of the band by BT contradicts several of the RA’s assignment policies and therefore it
is not a given that the current usage will be the same following take back by the RA.
It is also important that Industry is part of any decision making process to ensure that the
RA are made aware of future deployment requirements (networks and technology) to
ensure they are factored into any decisions taken.
Discussions with Industry should start now to ensure that the band is available for
widespread use in August 2003. The proposal would be to initiate discussions through the
PPWG and FLCC groups and request feedback on the future use of the band. These
discussions would culminate in firm RA policy that would become effective in August 2003.
Date:
Meeting:
8th May 2002
PPWG
Document Reference:
Paper No:
pr533572014
MOBILE (not
used)
FSS (Space to Earth) - [Astralink, Spaceway etc]
NGSO FSS
(Teledesic)
EESS
BSS Feeder
Links
MSS
Feeder Links
FIXED SERVICE
Existing BT low-capacity systems
(10/20MHz spaced)
1
17.
7
17.
8
2
17.
9
3
18.
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4
18.
1
5
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New BT low-capacity
systems
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as 38GHz)
High / medium capacity(7BT
systems
SDH
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4
7
18.
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18.
18.
6
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