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时间:2010-07-20 23:38来源:蓝天飞行翻译 作者:admin
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10.4.3.2 C channel power management
10.4.3.2.1 The GES calculates the initial EIRP of the C
channel according to the value derived from the worst case
link budget.
10.4.3.2.2 The GESs can be assigned power budgets
consistent with performance requirements of the channels
Attachment A to Part I Annex 10 - Aeronautical Telecomnunicatioits
operating to the satellite. Once this power budget is fully
utilized, the GI3 management rejects further channeldcall
requests until sufficient power has been released to be
assigned to the new requests or until the log-on request LIDU
indicates AES in distress. The C channel power can be
controlled for example in accordance with the following power
control decision table:
for the 21 000 biWs, rate lI2 FEC channel, if the
average number of errors per 2 560 channel bits
(before decoding) is:
greater than 172: increase EIRP by 2 dB
between 11 9 and 172: increase EIRP by 1 dB
between 76 and 119: leave EIRP unchanged
between 44 and 76: decrease EIRP by 1 dB
less than 44: decrease EIRP by 2 dB.
Note.- These values correspond to the input bit error
rates to a rate 112 fiterbi decoder as spec@ed for the
C channel that provide an output bit error rate of lu3
(nominal) to 10"' (1 dB above nominal), with a margin of
1.5 dB.
10.4.4 GES PRE-EMPTION MANAGEMENT
10.4.4.1 Voice versus voice pw-emption
The pwpose of this capability at the GES is to make resources
available for a higher precedence voice call if there are no
additional resources available at the GES and lower precedence
voice calls are being serviced. The GES management,
upon receipt of a request from circuit-mode services for a
channel unit for a voice call, checks if the precedence of the
new request for voice call set-up is higher than any call
already in progress. If the precedence of new call request is
higher than any one call-in-progress, the GES management
then ruthlessly preempts the lowest precedence call in
progress to make resources available for the higher precedence
call. If there are more than one call at the lowest precedence
in progress at a given time then it is at the discretion of the
GES operator to pre-empt a call. One option could be to preempt
the call which has been in progress for the longest time.
However, a higher precedence voice call does not pre-empt an
operational P channel to make resources available for setting
up a higher precedence voice call because doing so will be
detrimental to data transmissions from the AES.
10.4.5 GES SYSTEM BROADCAST
10.4.5.1 System table b d c a s r
10.4.5.1.1 This facility at the GES allows the GES to
update the system table informatio~ stored in an AES. The
system table updates are transmind to AESs as complete or
partial sequences.
10.4.5.1.2 The initial search data in the system table
contains satelliteheam-identifying P,,, channel frequencies for
all satellites. Any changes to the system table are made
centrally by the satellite system provider and are disseminated
to all GESs within all the satellite service areas provided by
the satellite system provider, as required. The revision number
for a system table is unique to each satellite service area.
10.4.5.1.3 The complete sequence is transmitted by the
designated GES on the satellitelbeam-identifying P,, channel
and it comprises all broadcast LIDUs headed by a broadcast
index LIDU. The partial sequence comprises of one or more
broadcast LIDUs headed by a broadcast index LIDU. The
partial sequence contains the most recent updates only. The
broadcast index LIDU identifies the presence of individual
LIDU series within both the complete and partial sequences.
Each GES broadcasts a partial sequence on all its operational
P channels. Each satellite service area has its own system table
broadcast information.
10.4.5.1.4 The system table complete and partial sequence
broadcast rates may be reduced due to high P channel loading.
This may delay the initiation of the log-on procedure at the
AES. It is recommended that the GES management monitor
such broadcast rates and provide further P channel capacity to
maintain these rates at acceptable levels.
10.5 Considerations for GES services
10.4.4.2 Data versus voice pm-emption
The purpose of this capability at the GES is to make resources
available to set up an additional P channel for higher
precedence data traffic when there are no additional resources
available at the GES to set up an additional P channel, and
lower precedence voice calls are being serviced and transmission
of additional data traffic on the already operational P
 
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