Advanced Telecommunications,
throughout Rural Africa

GSM Rural Extension | Site Installation

System Topology

RascomStar’s Rural Extension Service is typically
configured to operate as a terrestrial extension
of the mobile operator’s network, in which our
satellite interconnects to, and becomes an integral
part of, the incumbent mobile operator’s
terrestrial network. The Skylinx GSM
Communications System operates as:

Rural Extention

The above diagram shows a global representation
of the network-to-network interconnection.

Rural Extension

Fully integrated rural site

rural extension

VSAT antenna and GSM tower

The satellite system consists of a 1.2m to 2.4m antenna. 3W or 8W transmit amplifier with block up converter. A low noise block receiver amplifier, and one or more 4-channel satellite modems depending on the backhaul capacity required.

The GSM equipment includes the GSM antennas – 1 to 4 x base transceiver station and a base station controller, housed in separate IP66 rated out-door enclosures. In addition, the design provides operation to +55°C ambient temperature.

The satellite modem used at a rural site is called the baseband unit. The baseband unit is an all-weather, outdoor unit with the integrated functionality of five modems – one signalling modem and four traffic modems. Several baseband units can be combined at any rural site to match traffic capacity.

Network Architecture

RascomStar provides a fully integrated GSM service solution comprising of a seamless integration of satellite and GSM technologies functioning as an extension of the local Mobile Network Operators network.

The value proposition for the GSM subscriber is:

A completely standard GSM cell-phone and Sim card can be used.

Direct access to the MNO network in a rural location using standard dialing numbers[no special dialing codes or prefixes required].

Re-charge of pre-pay credit can be done as normal with standard MNO recharge cards.

All standard MNO services are available – Voices, SMS, USSD and Data [Edge @ 2.7 G] plus the designated MNO service codes for technical support from the MNO.

In summary, the Rascomstar GSM service solution is entirely seamless for the local subscriber in a rural location.

An extension GSM network connected via satellite
with its own GSM core components, such as
Mobile Switching Centre, Call Manager
Home Location Register[HLR], Visitor Location Register[VLR],
Serving GPRS Support Node [SSGN] and
Media Gateway

An extension to an existing terrestrial GSM
mobile network operator by using only a
satellite protocol translation core to
interconnect between the satellite network
and the existing terrestrial network utilizing
the mobile operator GSM core components
all communicating over standard E1/MAP or
SS7 over IP (SS7oIP / SIGTRAN) protocols.

The benefits for the MNO/GSM Operator are:-

Provision of the rural GSM site is entirely managed by Rascomstar.

All rural GSM service delivery, operations and maintenance up to the MNO core network interconnect are managed by Rascomstar and their service partners

All Rural Extention GSM Service technical support and development is provided by Rascomstar and their technology partners.

All Internationally Approved GSM technical standards are fully maintained in the Rural Extension GSM Service design and operation

It is physically interconnected with the mobile switching centre through:

– SS7 signalling link for all voice and short messaging service

– SGSN to GGSN IP link for Edge data

The platform logs all the KPIs key performance indicators from the OMCR.

Remote GSM Terminal Site | Includes:

One GSM tower (20 to 40m)

One integrated solar system with solar panels, solar controller and batteries to power all the telecom equipment on a 24/7 basis

One VSAT satellite antenna with transmit and receive capability

One intelligent Skylinx unit able to link the traffic from the base transceiver station to the satellite

1 to 4 rugged base transceiver [BTS] units service depending on the planned traffic capacity, equipped with Omni or sector GSM antennas

GSM Installation Sequence


Base Transceiver Station:

Single or Dual TRX GSM 2.5/2.75G BTS with integrated or external booster amplifiers

Up to 6 TRX per site with BTS, BSC, RT-BBU packaging choices

Sector or Omni antennas

Base Station Converter:

Referred to as “Satellite-Base Station Controller” performing the following functions
– GSM protocols to SIP / RTP and other protocol conversions for suitable transport over the satellite, including local switching functionality (Proxy/VLR).

Satellite Network:

Outdoor operation ‘Skylinx’ quad modems for voice and data transmission – up to 12 baseband units with packaging choices and transcoder scaling

VSAT Satellite antenna with Block Up Convertor [BUC] and Low Noise Block [LNB]