User's Manual

Teklogix 9150 Wireless Gateway User Manual 99
Chapter 5: Base Station Configuration
Overview
5.1 Overview
The 9150 Wireless Gateway can function as either a wired or wireless Base Station,
or as a Remote Radio Module (RRM), using a radio link and Psion Teklogix propri-
etary protocols to facilitate communications with the terminals (see also “Radio Pro-
tocols” on page 7).
As a wired base station, the 9150 can communicate with both wireless base stations
and terminals using either Adaptive Polling/Contention or Wlan Protocols (see page
11), and is connected to the network controller over a network.
As a wireless base station, the 9150 communicates with the wired base station and
mobile terminals using the Wlan Protocol.
As an RRM, the operation and timing of the 9150’s radio link to the terminals is
directly controlled by a network controller that uses a timeplexing radio protocol
(see “Timeplexing And Cellular Switching”, below). It is connected to the network
controller over a network.
Timeplexing And Cellular Switching
There are two methods of operating on the radio link. The first method is called
cellular switching. It is similar in concept to cellular telephone systems. Here,
each base station uses a different radio channel. The terminals monitor the radio link
and automatically switch to the channel with best radio reception. This cellular
switching capability is transparent to the host.
The second method is called timeplexing. Here, all Remote Radio Module (RRM)
bases at the site use the same channel. Over a UDP/IP network, a network controller,
or the 9150 as a mini-controller, coordinates the polling sequence so that the RRMs
do not transmit simultaneously. This timeplexing capability is also transparent to the
host. Timeplexing is suited for sites with low transaction rates.
Cellular switching and timeplexing can be combined within one Teklogix system:
a site may operate on two or more channels, with several grouped timeplexed bases
using each channel, and cellular switching between the channels.
In all of these cases, the operator may move freely throughout the site without loss
of communication. The Teklogix system handles channel-switching and handovers
between bases without alerting the user.