COBHAM Sailor 250 FleetBroadband, Training Manual, Page: 17 / 270

7
SAILOR FleetBroadBand
Training Manual
1
Under ideal conditions the most powerful FleetBroadband can
transmit and receive at a data rate of 492 kb/s before subtracting
signalling overheads.
Each of the FleetBroadband will have different capabilities. Sharing
capacity efficiently among different populations of system classes
with different capabilities and in different link conditions across
the satellite coverage requires considerable flexibility in managing
channel capacity. There are a number of capabilities shared by all
the current three FleetBroadband classes.
A FleetBroadband system can transmit bursts of up to 200 kHz in
bandwidth and can receive one or two carriers at a time (typically
one) also within a 200 kHz band.
The frequency tuning of a FleetBroadband transmitter and receiver
operate independently.
FleetBroadband can transmit and receive simultaneously.
FleetBroadband receive continuous forward transmissions but
transmit in 5 msec. or 20 msec. bursts in the return direction.
FleetBroadband transmit either intermittently or up to a 100% duty
cycle.
Once the FleetBroadband has acquired the global beam carrier
all subsequent FleetBroadband receive or transmit tuning is
commanded by the RNS.
FleetBroadband can support multiple traffic connections
simultaneously.
Different FleetBroadband classes have different capabilities in
terms of numbers of connections that they can support. As far
as the RNS QoS (Quality of Service)management is concerned
these connections are managed no differently to connections from
separate FleetBroadband’s.
At present the network supports
no more than one circuit
switched call per unit.
Up to eleven simultaneous IP connections are supported
(FleetBroadband class permitting).
1.3.2 Subscription and Quality of Service (QoS)
When a traffic connection is initiated the BGAN Core Network
checks that the user has subscribed to the service that they have
requested. For IP services, the subscription dictates which IP
networks the user is permitted to access via BGAN (e.g. corporate
VPNs). For each of these networks the subscription sets the
maximum quality of service (bit rate, traffic class etc.) that the
user is permitted to request when initiating a packet session to
that network. The QoS (Quality of Service) parameters supported
in BGAN follow the UMTS Release 4 as specified by the UMTS
standardisation body, 3GPP.
The subscription sets the maximum QoS for an IP connection but a
user may choose to connect using a lower value. E.g. a subscriber
can use a variable bit rate connection even if the subscription to
the IP network permits a guaranteed bit rate but not vice versa.