User's Manual

TS4000 Radio Modem User’s Manual AirNet Packet Protocol 24
Control Description
Slot Time This sets the transmit slot time (see Setting Slot Time).
Min Idle Slots This sets the minimum number of idle slots before a
modem attempts transmission (see Setting Min Idle Slots).
If the minimum number of idle slots is set to zero the
modem randomizes its transmission attempts with the first
slot after the channel becomes idle. For values greater
than zero, the modem waits that many slots before
randomizing its transmission attempts.
Tx Index The transmission index (TI) is the inverse of the probability
of transmitting in an idle slot. An index of 4 corresponds to
a 1/4 or 25% chance of transmitting in an idle slot. The goal
of setting TI is to maximize efficiency on the channel. If TI
is set too low then transmissions collide too often. If TI is
set too high then there is excessive unused channel time in
the system (see Setting Transmission Index).
Min Idle Slots and Tx Index can be set differently for different types of packets.
The following table describes the different packet types.
Type Description
Data Packets These are any packets that carry user data. These include
data packets for all the different types of transfers (i.e.
Individual, Individual w/o ACK, Broadcast). These values
are set on the Packet for Port tab.
ACK Packets These are the acknowledgment packets for the individually
addressed data packets. These values are set on the
Packet for Port tab.
Relay Packets These are any packets that are relayed with the store and
forward relay option. Both data packets and ACK packets
can be relayed.
Selection Description
Disabled No network broadcast packets are relayed.
Enabled All network broadcast packets are relayed.
Selection Description
None No broadcast packets are relayed.
Some The broadcast packets that are relayed is determined by
the broadcast relay addresses control.
All All broadcast packets are relayed.
This control consists of a list of broadcast addresses. Each address in the list is
a group address for which broadcast packets are relayed. The user can use as
few or as many (up to the list size) addresses as desired.
CSMA MAC Setup
Network Broadcast
Packets - Relay All
Group Broadcast Packets -
Relay Activate
Broadcast Relay
Addresses