The following diagram illustrate major
components in two-way radio system. The diagram shows a typical wide
here for description for each
Typical Network Component
In a typical
configuration, a wide area radio network consists of 3 major
Note that the
above configuration applies to a wide area radio network. For a
single site radio network, typically there is no centralized
switching system. Its ‘switching’ or commonly known as controller
resides in the same physical location as Base Station. Thus, a
single-site radio network consists of:
Base station or site repeater (which includes site controller)
as: Subscribers Unit, Radio Unit, Mobile Station, Portable Radio,
Mobile Radio, Fixed-Station Radio
This is a
device for the user to communicate and interface to the network. For
end-users, they will mostly see these devices more often than the
radio infrastructure itself. Thus, the ergonomics and performance of
radio terminal (i.e. size, weight, battery life, user interface and
ease of use) plays important role for end-user’s acceptance of radio
radio terminal can be classified into:
This is the
device that users can carry while in the move. Since users carry
this device most of the time, the ergonomics of portable radio (i.e.
size and weight) is one of important factors for users. However,
size, weight and battery life are, among others, factors that limit
the performance of radio unit. Portable radios usually have lower
power output compared to mobile or fixed-station radio due to the
above limitation factors. Thus, the range of portable radio is
typically smaller than mobile or fixed-station radio. In many cases,
portable radio with higher power comes with bigger form factors.
Usually there will be a trade-off between the size of portable and
power output. Either you can have smaller form factor radio but
lower power or higher power but bigger form factor.
This is the
device that permanently installed in a vehicle or a car. The size
and weight of this mobile radio is bigger than portable radio but it
usually does not really matter to user because mobile radio is
permanently fixed into the vehicle (i.e. users do not have to
‘carry’ a mobile radio). Typically, mobile radio has higher power
output than portable radio due to its form factor which facilitate
more components to produce higher power as well as it does not have
issue with battery life (it uses vehicle battery for its power).
Thus, the range of a mobile radio is usually greater than portable
This device is
usually installed in a fixed location such as a branch office or a
field post. Typically, a fixed-station radio is a mobile radio with
a power supply, external microphone or speaker and better antenna
system (such as directional antenna). Thus, the range of
fixed-station radio is greater than mobile and portable radio.
Base Station or Repeater
as: Site repeater, RF Repeater, Site
This is a
network component that provides RF coverage in a radio network. In
typical configuration, a base station can consist of RF Repeater(s),
Controller(s), antenna distribution system (i.e. duplexer, combiner,
etc) and Power Supply.
traditional Two-way Radio world, the term Base Station is
also known as a fixed station that receives a signal but do not
re-broadcast the signal to other radio users in the system. This
configuration allows an operator, commonly known as the dispatcher,
sitting in the office to communicate with the radio terminals in the
field. The term Repeater is used referring to a transceiver
that receive a signal and re-transmit it at the same time. The
primary purpose of repeaters is to extend coverage. The main
difference between base station and repeater is that a repeater
repeats a signal that it receives, a base station doesn’t.
term of Base Station and Repeaters are often mixed referring to
network component that provides RF coverage.
In one radio
network, there can be multiple base stations or repeaters to provide
necessary coverage. In a wide area configuration, these base
stations are connected to a central switch that manages the entire
network. The connection from the base stations to switch is called a
Switching System or Controller
as: Central controller, central switch, Mobile Switching Office (MSO)
This is a
network component that manages the entire network. The switching
system, for example, manages the traffic in and out and route the
communication to and from base stations. Switching system is the
brain of the network without which the network will not be able to
handle wide area network calls.
configuration, a switching system can consist of multiple devices or
equipments. Each equipment handles specific function. For example,
one equipment handles the routing of the calls while the other
handles interaction with base stations. More often than not, these
devices or equipments are placed in rack(s) or cabinet(s). Depending
on the complexity of the network, the switching system can have from
one to tens of racks.
Mobile Switching Office (MSO)
as: Switching system, Controller, Central controller, central switch
This refers to
physical location where all of network switching or controller is
placed. This term is derived from cellular network for a common term
to refer to its switching system. Since the switching system is
located in one physical location, the “generic” term is Mobile
Switching Office (MSO) with an “office” word added to emphasize a
location that accommodates various equipment of the switch.
radio, this term is sometimes also used to refer to the radio
switching system, especially for radio network with complex
switching system. A digital trunked radio system like
example, has an architecture similar to a cellular system. Its
switching system is as complex as the cellular system. Thus, the
iDEN switching system sometimes refers to iDEN MSO.
This is a
facility to connect base station(s) to its switching system.
Depending on the technology and products, site link can be E1,
partial E1, microwave, 4W, fiber-optic network and any other means
to connect base station to its switching with necessary bandwidth
and performance. In many radio network installations, site link(s)
can be leased from a telecom provider (i.e. E1 line) or owned by the
organization (i.e. microwave). Leased line will typically incur a
monthly recurring cost but has lower maintenance cost while
privately owned link will need a higher capital expenditure to buy
the equipment and maintenance expenses but organizations do not to
need to pay monthly subscription like leased line.
several discussions on the use of satellite as site link. The long
delay of satellite link is one of the main factors that need to be
considered for two-way radio network implementation, especially for
group call type of communication. The use of satellite link for
two-way radio is discussed in the
This is a
device connected to the base station / repeater to propagate the
Radio Frequency (RF) energy. Antenna system plays an important role
to determine the efficiency of converting electrical energy into RF
energy. Thus, determine the area of coverage.
several antenna configurations to meet various condition and
antenna parameters are:
This is the range of the band that the antenna will operate in (i.e.
806-870 MHz). This only means that the antenna will operate within
this band. It usually does not necessarily mean that the antenna
will operate over the entire band.
The maximum frequency separation that this antenna will operate
within the frequency band.
Antenna gain is proportional to the product of directivity and the
antenna’s efficiency. Directivity is a measure of how an antenna
focuses energy. Antenna’s efficiency accounts for loss associated
with antenna. Gain is achieved in an antenna by re-directing energy
from some directions into the desired directions. The higher the
gain of the antenna, the further the coverage obtained. However, a
higher gain antenna typically means higher cost.
In Two-Way Radio, there are usually uni-directional antenna or
omni-directional antenna. The names reflect the radiation pattern
produced by each type of antenna.
Look for the specs with
input power rating of the antenna is greater than the RF power
output rating of the transmitter(s).
Standing Wave Ratio):
A high VSWR
(Voltage Standing Wave Ratio) implies a large amount of reflected
power. This means that the amount of forward power is less.
Therefore, the higher the VSWR, the less efficient the antenna.
This refers to the physical length of the antenna. A long
antenna is cumbersome to ship, store or install.
areas, the load of the wind on the antenna must be taken into
Dispatcher or Console System
This is a
network sub-system where an operator, commonly known as dispatcher,
interface with the network to monitor users’ activities and
communicate with users in the field. The dispatcher acts as the
central focus of the most two-way radio system and usually has more
powerful features to allow the dispatcher operator to effectively
monitor and manage the users in the field. The dispatcher is usually
located at organization’s control center (also known as: Command and
Control room or Monitor room).
two-way radio system, console or dispatcher system has various
buttons and LEDs to facilitate monitoring and managing various talk
group. In a modern two-way radio system, these buttons and LEDs are
replaced with Personal Computer equipped with specialized Digital
Sound Processing (DSP) card and other specialized equipment to
facilitate monitoring and managing users effectively. Many
dispatcher and console system has a Graphical User Interface (GUI)
for ease of use.
Network Management System
This is a
network sub-system to monitor and manage all related components in
the entire network. Depending on the products, Network Management
System can vary in term of functionalities and performance. An
industry standard for network management which follows the Open
System Interconnection (OSI) reference model will have, at least,
the following functional management known as FCAPS:
Performance management, and
In modern two-way
radio system, the Network Management System uses computerized
system, such as Personal Computer with specialized hardware and
software to perform the function. The use of Personal Computer with
Graphical User Interface (GUI) will make it easier for network
manager to monitor and manage the network.
Area of Coverage
coverage indicates the area where the radio terminals have usable
signal (uplink and downlink) to use the radio network. The usable
signal means an acceptable signal level that allows user to
communicate. A term that is mostly used in area of coverage is
coverage reliability. A 95% coverage reliability means that there is
95% chance that user will have the acceptable signal level in
particular area of coverage. The higher the number, the better the
coverage but it usually comes with higher cost due to the need to
build more base station or repeater sites.