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J-Series Data Radio – User Manual
Introduction
Fundamental to understanding the use of J-Series Ethernet Data Radios in your system is the need for a basic understanding of the different types
of radio network topologies (known as NETWORK TYPES) and the function of each radio within them (known as RADIO TYPES).
The following table provides a brief overview of each:
Network Types:
Point to Point (PTP): One Access Point radio is configured to communicate with a REMOTE radio in PTP mode.
Point to Point via Bridge (PTP/B): As per PTP mode but with additional network range extension using a LinkXtend™ Bridge.
Point to Multipoint (PTMP): One Access Point radio is configured to communicate with multiple REMOTE radio(s) a PTMP network
Point to Multipoint with Bridges (PTMP/B): As per PTMP network but with additional network range extension using a LinkXtend™ Bridge.
Radio Types:
Access Point: Defines the Access Point radio in a network. The function of the Access Point is to provide synchronization of the network and
management of the radio protocol. There is always one Access Point per network.
Remote: A remote radio in the network. The function of a remote is to communication with the Access Point either directly or via one or more
Bridges.
Bridge: A radio that provides network extension between an Access Point or another BRIDGE and additional REMOTES. A BRIDGE is a
device with dual personalities, behaving as a REMOTE to its Access Point for 50% of the time, and then behaving as an Access Point for its
REMOTES for the remaining time.
Each type of network is described in the following diagrams.
Point-to-Point Networks (PTP)
A Point to Point (PTP) network has one Access Point and one Remote radio. The available data bandwidth is shared between the two radios in
each direction. Because a PTP network only has two radios, the over-the-air protocol can be optimized to provide best possible bandwidth, latency
and security.
Each hop is divided into two halves. The Access Point can transmit in the first half and the Remote in the second half. This mode of operation is
called Pseudo Full Duplex due to the shared division of available bandwidth. Due to the well defined nature of channel access in PTP mode, data
collisions due to the Access Point and Remote trying to access the channel at the same time do not occur.
Pseudo Full Duplex has the advantage that it appears to the connected device to be a full duplex cable with a specific bandwidth (i.e: even if
one devices transmits continuously it will not block the other device from sending data). This is useful for applications that expect full duplex
communications or that are not designed to be radio modem friendly. The disadvantage of Pseudo Full Duplex is that the bandwidth is divided
equally for each direction, even if one direction does not use it’s available bandwidth.
Receipt of data (in either Access Point to Remote OR Remote to Access Point directions) is acknowledged by the receiving radio. This provides the
most efficient means of guaranteed data delivery as data does not need to be blindly “re-transmitted” which decreases the available bandwidth. For
more information on data acknowledgements and retransmissions refer to Part D - Features.
It is also possible to create a Point to Point (PTP) network using the Point to Multipoint (PTMP) Network Type and using only one Remote. In the
PTMP mode, system bandwidth is not shared equally, but when additional REMOTE sites are added at a future date, the existing radios will not
need to be re configured making additional Remote site deployment easier.
Part C – Network Types
Part C – Network Types
Содержание JR240
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