PHONE SYSTEM MOVING VEHICLES BY USING VSAT

Principal components.
In moving vehicle telephone system using VSAT is
principal components that are supporting the implementation of the system
telecommunication. In this case there are basic components of
Telephone System Moving Vehicles (STKB) and the main components of
VSAT itself.

Principal components STKB.
There are three main components of this system support, namely:
- Mobile units (units that move) in this case the customer aircraft as
car (car mounted), portable telephone (portable) and mobile phones
(handheld).
- Radio Base Station (radio base station) / RBS / Cell Site is
liaison between the unit moved to the central (Mobile Switching
Center / MSC).
- Mobile Switching Center / MSC (mobile telephone) has the function
such as public telephone / Public Service Telephone Network (PSTN) that is
carry out the functions:
1. Giver direction (Routing)
2. Control (Controlling)
3. Signaling (Signaling)
4. Giver of charge (Charging)
and other functions such as movement (hand off) and the exploration
(roaming).
MSC is the coordinator of all the cells in one service area and as
link between cellular systems with public telephone network (PSTN).

Principal components VSAT.
VSAT network consists of three main components, namely: satellite (using
satellite Palapa B1), Main Station or Station Controller Axis (HUB
station) and Micro Earth Station (SBM / VSAT).
Micro Earth Station (SBM / VSAT) consists of two units: Unit of Foreign Buildings
(REPEAT / Outdoor Unit) and Unit In Building (UDG / Indoor Unit) of each
associated with the Inter-Facility Liaison (PAF / Interfacility Link).
REPEAT form a parabolic antenna with a diameter of 1.8 meters and RF unit
an antenna attached to it. UDG and physical form is a
PC-like box. SBM / VSAT is installed at the user location.


Judging from its physical form, no other Axis station is a station
traditional earth who have satellite dishes with a diameter of 10 feet.
Pancarnya 400 watts of power, almost 100 times the power transmit owned SBM / VSAT.
In broad outline the components of the shaft station are:
1. Packed Switch / Network Control System.
2. IF subsystem at HUB station.
3. RF subsystem.


Shaft station (HUB station) serves as a control network works
communication systems SBM / VSAT are:
- Writing an address
- Monitoring the transponder and host relationships
- Monitor and control the data path through the network

- Controlling access to the satellite.

Wireless Communication System using VSAT.
Mobile communications system using VSAT requires a
geostationary satellites. In systems using VSAT, satellite
used to work in the Ku-band frequencies (14/12 GHz) or C-band (6 / 4 GHz).
Satellite relationship is only used to connect the MSC with the Remote
Switching Unit (RSU). This relationship brings traffic control network
form of data and provide a sound relationship between the remote switching
MSC. Thus, customers do not have aircraft large power and
aircraft used handheld.

Customers moving operating at 800 MHz to communicate with RBS
nearby. Calls then forwarded to the mobile switching through connections
satellite. Mobile switches go back through the PSTN to the destination.
Transmit power SBM / VSAT only 5 watts. With a relatively small power and
small diameter of the antenna which also does not allow signal
emitted from one SBM SBM acceptable goal. Therefore
signal amplifier is required. In this case conducted by the shaft station (HUB
station).
So how inter SBM basically done through two beam
namely from the SBM to the station axis (first broadcast) and from the station to the axis
SBM destination (second stream). For a one-time broadcast takes
0.25 seconds, because the beam is twice the time required 0.5 seconds. With
Thus SKSBM communication network via a delay (delay inherent)
is approximately 0.5 seconds. This is when used for communication
Voice will feel slow and allow to happen collisions
sound.

STKB network.
In each service area a few RBS is connected to a Remote
Switching Unit (RSU). RSU connected to the MSC via a satellite connections
and connected with PSTN telephone exchange with terrestrial connections
(cables). With this RSU happened some reduction MSC functions,
functions such as hand-off between RBS is handled by one RSU and to
call to PSTN subscribers in the area around RBS directly forwarded to
central PSTN connected to the RSU - not through the MSC.

Satellite Access Method.
To streamline the use of satellite capacity used access method
-DAMA MCPC (Multiple Channel Per Carrier - Demand Assignment Multiple Access)
for voice connections and Slotted ALOHA for network control channel. Each
RSU can build communication with other RSU or MSC with some
carrier.

MCPC, DAMA.
Multiple access on request (Demand Assignment Multiple Access)
enables the delivery of information when the recipient needs it
(ask). In other words, the information can be pool, while
others can also be accessed when needed.

ALOHA.
Random access TDMA, or ALOHA is another method of discipline major TDMA
(Gbr.3.4) which simply fill in a transmit data buffer and
then send it randomly. The earth station will wait for
certain period until the same information is sent back
(retransmitted) and there is expected to clean the canal to catch
transmission (delivery).


ALOHA allows the emptying of a buffer from the transmitter only at the
certain, if not so then the system is relatively simple
will be complicated; it would still work well if still unmanageable
properly and not overloaded.