channel
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Satellite channel characteristics may have an effect on the way
transport protocols, such as the Transmission Control Protocol ...
... Pos81], behave. When protocols, such as TCP, perform poorly,
channel utilization is low. While the performance of a transport
protocol is important, it is not the only consideration when
...
... satellite leaves the ground station's sight, another satellite
appears on the horizon and the channel is switched to it. The
propagation delay to a LEO orbit ranges from several milliseconds
...
... effects such as rain attenuation. For mobile applications,
satellite channels are especially susceptible to multi-path
distortion and shadowing (e.g., blockage by buildings). Typical
bit ...
... transponders. Traditional C band transponder bandwidth is
typically 36 MHz to accommodate one color television channel (or
1200 voice channels ...
... channel (or
1200 voice channels). Ku band transponders are typically around
50 MHz. Furthermore, one satellite may carry a few dozen
...
... Although satellites have certain disadvantages when compared to fiber
channels (e.g., cannot be easily repaired, rain fades, etc.), they
also have certain advantages over terrestrial links. First,
...
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Satellite channels have several characteristics that differ from most
terrestrial channels. These characteristics may degrade the
...
... Satellite channels have several characteristics that differ from most
terrestrial channels. These characteristics may degrade the
performance of TCP ...
...
Due to the propagation delay of some satellite channels (e.g.,
approximately 250 ms over a geosynchronous satellite) it may take
...
... protocol should have "in flight" (data that has been transmitted,
but not yet acknowledged) at any one time to fully utilize the
available channel capacity. The delay used in this equation is
the RTT and the bandwidth ...
... traffic via the satellite
channel. Another common situation arises when both the incoming
and outgoing traffic are sent using a satellite link ...
... transmitter required to provide a high bandwidth
back channel. This asymmetry may have an impact on TCP
performance ...
...
Most satellite channels only exhibit a subset of the above
characteristics. Furthermore, satellite networks are not the only
...
...
It is recommended that those utilizing satellite channels in their
networks should use the following two non-TCP ...
... The data link layer protocol employed over a satellite channel can
have a large impact on performance of higher layer protocols ...
... DF) bit. If the packet is too large to be forwarded without being
fragmented to a given channel along the network path, the gateway
...
... sender
and receiver. Satellite delays can aggravate this problem (consider
the case when the channel between G1 and G2 is a satellite link).
However, in practice, Path MTU Discovery ...
... BER and segment size is likely to vary
depending on the error characteristics of the given channel. This
relationship deserves further study, however with the use of good
forward error correction ...
...
Therefore, for TCP to operate efficiently, the channel
characteristics should be such that nearly all loss is due to network
...
... the available capacity of the link. These mechanisms may also be
needed to fully utilize fast terrestrial channels. Furthermore,
these mechanisms do not fundamentally hurt performance in a shared
...
... start and congestion control algorithms can force poor
utilization of the available channel bandwidth when using long-delay
satellite networks ...
... start takes more real time over GSO satellites than on typical
terrestrial channels. This holds for congestion avoidance, as well
[All97 ...
... bandwidth. This is especially true over long-delay satellite
channels because of the large amount of time required for the sender
to obtain feedback from the receiver ...
... Therefore, using the maximum window size of 65,535 bytes and a
geosynchronous satellite channel RTT of 560 ms [Kru95] the maximum
...
... T1 rate (approximately 192,000 bytes/second) GSO satellite
channels. However, TCP has been extended to support larger windows
[JBB92 ...
... slow start algorithm can be time consuming over satellite
channels. When SACKs are employed, the sender is generally able to
determine which segments ...
... networks containing satellite channels. Those mechanisms marked
"Required' have been defined by the IETF as required for hosts ...
... Research into improving the efficiency of TCP over satellite channels
is ongoing and will be summarized in a planned memo along with other
considerations, such as satellite network ...
... link layers can provide secure
communication over satellite channels. However, this still leaves
traffic vulnerable to eavesdropping on networks ...