MPM-1000A Operator Manual
1000-7075 Rev E
8-7
Accurate Terminal and Satellite parameters are required to compute accurate path
losses and to predict an accurate total C/No value for a link. Accurate Terminal
parameters and settings are required so that a Terminal commanded to transmit at a
given power level implements exactly that power level. This is important, not only for
closing the link, but also to meet the total power constraint at the Terminal and at the
Satellite. The power level, along with the Terminal Antenna aperture, affects the
spreading needed to meet the EIRP density requirement.
8.5 Network Operation with Wideband Global Satellite
The Wideband Global Satellite (WGS) carries a combined X-band/Ka-band payload.
Transponder channels in the X-band are 47 MHz, 50 MHz and 125 MHz wide, while
transponders in the Ka-band are 125 MHz wide. Each transponder channel is
partitioned into a discrete number of sub-channels, each of which is 2.6 MHz wide. For
example, a 125 MHz transponder contains 48 sub-channels. The WGS provides a
channelize-
switch (hereafter referred to as the “channelized”) that allows uplink
bandwidth to be in-band and cross-band connected in sub-channel increments on the
downlink. Reference 5 describes the channelized properties of the WGS.
The WGS also provides a mix of different beam footprint configurations to
accommodate the vagaries of theatre geographic deployments. In the X-band, both
earth-coverage and shapeable spot-beams are supported. In the Ka-band, both area-
coverage and narrow-coverage spot-beams are supported. A network operating over
the WGS may consist of nodes that are operating within the X-band and/or the Ka-band
and that are deployed within one or more beams.
Sub-channels can be Multicast (fan-out) or combined (fan-in). In the Multicast case, a
sub-channel in any uplink can be simultaneously switched into multiple sub-channels. In
the fan-in case, multiple sub-channels from two or more uplink channels can be
combined into a single sub-channel on the downlink. The fan-in capability is limited only
by the additive noise considerations of bandwidth combining the uplink sub-channels.
As with the basic channelized functionality, channel segments being fanned-out or
fanned-in can be any multiple of the basic 2.6 MHz sub-channel size up to the size of an
entire channel.
The NCW resource scheduler supports the following WGS Channelized configurations:
a. Up to 63 non-contiguous bandwidth segments of variable bandwidth per network.
b. Single beam network configuration with no fanned-in or fanned-out bandwidth
segments. (Note that fan-in and fan-out are not required in a single beam
configuration due to the assumption that all terminals within the beam can tune to
any bandwidth segment.
c. Multiple beam network configurations (including X-band/Ka-band cross-banded
operation) with the following bandwidth segment restrictions and allowances:
1) A network can support a maximum of 19 beams.
2) One and only one fully fanned-out group of bandwidth segments must be
established from every beam that provides connectivity into all other beams
including itself. Furthermore, if the NC and the alternate NCs are operating in
