XStream
‐
PKG
‐
T™
Telephone
RF
Modem
–
Product
Manual
v5.x00
[2006.02.24]
4.3.2.
Multi-Streaming Mode
Characteristics
: Enables exclusive connections [Definition is in Theory of Operation section.]
Supports the passing of large data streams (> 256 bytes) from multiple
remote modems to a base modem (If a complete data stream from a remote
modem is less than 256 bytes, data can be sent from several remotes to a
base location without enabling this mode and latencies will be much less.)
Transmissions never acknowledged (ACK) by receiving modem(s)
Required Parameter Values (TX Modem)
: MD = 1 (Base), MD = 2 (Remote), RN > 0, RR > 0,
MY
≠
0xFFFF
Recommended Use
: Use this mode in point-to-multipoint networks where remote modems
initiate communications and require exclusive (uninterrupted) connections to the base modem.
Table
4
‐
05.
Sample
Network
Profile
Modem
Parameter Settings
(assume default values for parameters not listed)
Base
ATMD 1
[configure modem as Multi-Stream Base] *
Remotes
ATMD 2
[configure modem as Multi-Stream Remote] *
*
When
Multi
‐
Streaming
is
enabled,
the
following
parameters
are
consequently
modified
(if
they
have
not
already
been
modified
from
their
default
states):
RR,
RN,
MY,
CD,
AT
and
BT.
[refer
to
Table
4
‐
06]
Theory of Operation
When in Multi-Streaming Mode, all remote modems can initiate communications with the base
modem at the same time, but only one remote is granted an exclusive connection. After an
exclusive connection begins, data is transferred exclusively between two modems without
interruption from any other modems in the network.
An exclusive connection is a bi-directional connection that can only be established when in Multi-
Streaming Mode. An exclusive connection is immune to other remote modems interrupting the
connection and interleaving data (The interleaved data potentially renders the base modem
unable to discern from which remote modem the data was transmitted).
When an exclusive connection is granted to a single remote, the other remotes are notified that
the connection exists. The notification causes the remote modems to postpone transmissions
until the base modem sends notification that the exclusive connection has ended.
Figure
4
‐
07.
Sample
Connection
Sequence
Diagram
CRP
=
Connection
Request
Packet
CGP
=
Connection
Grant
Packet
DRP
=
Disconnect
Request
Packet
(not
shown
in
diagram
–
applicable
when
remote
connection
is
disconnected
using
the
pin
sleep
I/O
line.
DGP
=
Disconnect
Grant
Packet
ACK
=
Acknowledgement
of
reception.
Base
modem
=
The
central
transmitting/receiving
modem
in
a
network
of
modems
that
maintains
communications
with
remote
modems.
Remote
modem
=
An
modem
in
a
network
of
modems
that
sends
data
to
and
receives
data
from
a
base
modem.
Payload
=
Data
contained
inside
the
RF
Data
of
the
RF
Packet
that
originates
from
a
host to be transmitted over the air
In the connection sequence above, an exclusive connection is first granted to “Remote m”. The
CGP (Connection Grant Packet) is broadcast to all remote modems in the network to
communicate the base in engaged in an exclusive connection. Upon receipt of the CGP
notification, remote modems will wait for a DGP (Disconnect Grant Packet) before attempting
again to send data to the base modem.
©
2006
MaxStream,
Inc.,
Confidential
and
Proprietary
34
