Comtech EF Data CDM-570/L Vipersat Parameter Editor - Manual (Page 51)

Chapter 2 - Using Parameter Editor 2-35
Vipersat
addressable within a network which, in turn, is defined by the network ID
number assigned to the modem/router.
In an STDMA group, the allocation of bandwidth is shared among the associ-
ated remotes. Depending on the number of remotes in a network, a Hub may
have multiple burst controllers, each with its own set of remotes. This is accom-
plished by assigning a unique Group ID number to each controller and its
remotes.
Note: The STDMA group number and the network ID are independent. There
can be multiple STDMA groups within a single network.
Slot Data Length
This parameter is active for the Hub modem only.
The Slot Data Length fields specify the data length, in milliseconds, for each of
the remotes in the STDMA group, and represents the amount of data that can be
transmitted or received in one spin of the STDMA cycle. This is the amount of
time that the remote is provided in the cycle to send data.
Depending on the Allocation Method that is chosen for the Hub STDMA
controller, the appearance of this parameter will vary:
• Fixed – Slot Length
• Dynamic Slot – Slot Minimum, Slot Nominal
• Dynamic Cycle – Slot Minimum, Slot Maximum
• GIR – Slot Minimum
• Entry Channel – Slot Minimum, Slot Maximum
Stats Collection
Active for Hub modems only.
The burst controller monitors statistics in the received ACK from each remote.
The statistics report the fill status of the STDMA buffers. The burst controller
builds a table of the group and calculates the relative buffer fill for each remote.
It then calculates the length of the data slot for each remote based on the Mini-
mum Slot size plus a percentage of the available bandwidth. Idle remotes would
receive a data slot equal to the Minimum Slot size.
In the Dynamic Slot mode, the dynamic range of STDMA is a function of the
difference between the Nominal Slot size and the Minimum Slot size parame-
ters. The speed with which STDMA reacts to changes in dynamic load is a func-
tion of the Stats Collection parameter and the Burst Map Rate parameter.
NOTE