Technology Trends In Rural Communications

1
Technology Trends In Rural Communications

• Sami Mohamed Sharif
• Electrical and Electronic Engineering Department,
  University of Khartoum, Sudan

2
The Changes Introduced by Telecommunication

• Telecommunications enables a whole range of
  commercial functions to be carried out quickly
  and easily
• Telecommunications makes it possible to obtain
  and to distribute information of all sorts
• Telecommunications brings the ability to carry
  out all sorts of transactions electronically
• Tourism is a commercial area, which is just not
  feasible without adequate telecommunications
• Education opportunities can be greatly expanded
  by tele-education or distance learning,
  techniques
• Telemedicine is an active and expanding field

3
Rural Telecommunication Systems 1

• range from very basic pay telephones, to digital
  wireless cellular telephones and sophisticated
  community Internet systems
• tools
• wooden telephone poles and copper telephone
  lines,
• analogue radio transmitters and receivers,
• low earth orbit satellite systems (LEOS),
• digital point-to-point microwave transmitters,
• towers and receivers,
• wireless local loops,
• fiber optic cables,
• local infrared light transmission and reception
  devices.
• rapid spread of rural "telecentres"

4
Rural Telecommunication Systems 2

• rural telecommunication systems are best
  described by their uses, which enable rural
  people and their organizations to communicate and
  share information
• Within communities and villages
• Horizontally to other communities and villages
• Vertically to friends, relatives, peers, and
  government and non-governmental organizations
  (NGOs) in urban and international contexts

5
Telecommunications Environment

• Telecommunication technologies have changed
  dramatically in the past decades
• technological innovations
• Wireless technologies
• Digital Compression
• VSATs
• Voice Messaging
• Store-and-forward data

6
Delivery of Telecommunication Services 1

• the practical and economically viable way to
  deliver telecommunication services in the rural
  and remote areas of developing countries is by
  providing a group of lines that provide access to
  the telecommunication services at a convenient
  central location within each rural community
• "universal access" to telecommunication services
  is an appropriate goal in the rural and remote
  areas of developing countries

7
Delivery of Telecommunication Services 2

• The location at which the services are provided
  is often called a "public call office" (PCO)
• provides sufficient lines to fully meet the need
  for both incoming and outgoing calls
• should provide appropriate value added services
  to meet the needs of the community
• messenger service upon receipt of incoming calls,
  
• voice messaging (a "virtual" telephone line),
• sending and receiving faxes, and
• public e-mail.
• facility, or appropriate portions of it, should
  be available at all hours of the day and night,
  not only during normal business hours

8
Delivery of Telecommunication Services 3

• The location at which advanced services such as
  these are offered is often called a "community
  teleservice center" (CTSC), or "multipurpose
  community telecaster" (MCT).
• a gradual and orderly process of evolution from
  PCO to MCT is normal and desirable
• The PCO/MCT constitutes a small and growing local
  commercial operation, providing some local
  employment

9
Principles for Providing Telecommunications

• Telecommunications is inherently a commercial
  enterprise, and a potentially profitable one
• Five key "principles" have been defined, which,
  taken together, have been found by experience to
  provide the appropriate framework for creating a
  profitable, and hence sustainable
• these principles address the rural and remote
  areas of a country in total

10
Technology Selection 1

• two main factors
• The geographical location, its remoteness from
  the switching center
• The voice, video, and data traffic volume and the
  capital and operational costs
• The technology options available are
• Terrestrial Line/Cables,
• Multi Access Rural Radio,
• Wireless Local Loop and
• Satellite

11
Technology Selection 2

• Locations that are closer to the switching
  centers
• can easily be covered by terrestrial and cellular
  system
• cellular technologies
• should cover sparsely populated users
  cost-efficiently using lower frequency bands
• Most popular used cellular technologies are
• CDMA-450,
• PHS,
• GMS-400, and
• the third generation cellular technology,
  IMT-2000

12
Technology Selection 3

• The places, which are within a distance between 5
  to 25 kms from the switching center
• best be covered by microwave systems like Multi
  Access Rural Radio and Wireless Local Loop.
• Narrow Band Packet Radio is a low-cost solution
  for rural connectivity.

13
Technology Selection 4

• Locations at distances beyond 25 kms from the
  nearest switching centers and those in hilly
  areas
• best be covered through satellite-based system.
• VSAT (Very Small Aperture Satellite) is a
  cost-effective solution.

14
Narrow Band Packet Radio Technology 1

• VHF and UHF radio systems have being used from a
  long time for voice communications in rural
  areas, due to their
• low cost and
• ease of installation solution.
• in many countries, amateur radio clubs use
  narrowband packet radio systems to access the
  Internet in a wireless and inexpensive manner,
  benefiting from the volume production of radios
  specially designed for this purpose

15
Narrow Band Packet Radio Technology 2

• A packet radio network consists of
• a transceiver,
• a terminal node controller (TNC),
• an antenna and
• a power source as a basic repeater configuration.
  
• The radio transceiver used in packet radio is the
  same as that used in voice communication.
• Instead of a voice grade modem,
• packet radio uses the terminal node controller to
  adapt the signals between the personal computer
  (PC) and the transceiver,
• to perform packet assembly and disassembly (PAD)
  as defined in the Amateur Packet-Radio Link-Layer
  Protocol (AX.25).
• Several manufacturers now produce TNCs at prices
  ranging from approximately SD 150,000 to SD
  1,000,000.

16
Narrow Band Packet Radio Technology 3

• Keep it Short Simple (KISS) is a second mode of
  TNC
• leaves the PAD functions to software residing in
  the PC
• main features of this mode are
• It allows the use of protocols such as
  transmission control protocol/Internet protocol
  (TCP/IP)
• It is possible to establish packet radio
  connection to a server in serial line Internet
  protocol (SLIP) mode, and therefore use Internet
  browsers such as Netscape Navigator
• The programming and operation of the TNC is quite
  simple
• The bandwidth limitations of packet radio
  networks are inherent to the low frequencies
  employed and the channels allocated

17
CDMA450 Technology 1

• A trial is currently (4Q 2000) underway to
  demonstrate the use of CDMA technology in and
  around the 450 MHz band.
• identified as cdma450
• the use of frequencies in the 400 MHz band,
  rather than 850 MHz or 1900 MHz, provides wider
  coverage from each base station
• CDMA450 covers the same area as a CDMA system at
  850 MHz using approximately half the number of
  cell sites.
• In applications where very extensive coverage is
  required, a software adjustment to timing
  parameters permits a range of up to 180 km under
  favorable conditions.

18
CDMA450 Technology 2

• These improvements will allow operators that
  serve rural areas to provide improved services
  for their subscribers. For example,
• services that support medical care,
• offer internet access
• with the potential for educational services and
• global market access for local small businesses

19
Personal Handy Phone (PHP) Technology 1

• The use of TDMA-based point-to-point (PTP) or
  point-to-multipoint (PMP) radio systems with
  wireless local loop tails I
• a fairly recent phenomenon, having been
  introduced in rural areas over the past three to
  four years.
• the substitution of wireless systems for copper
  cables in the local loop helps reduce the
  maintenance costs associated with physical plant
  in rural areas.
• the implementation of point-to-point and
  point-to-multipoint systems with one of two
  wireless local loop technologies
• Personal Handy phone System (PHS) and
• Digital Enhanced Cordless Telephone (DECT).
• These technologies have been standardized on
  either national or regional bases, the former in
  Japan, and the latter in Europe.

20
Personal Handy Phone (PHP) Technology 2

• The available reports described
• the implementation of integrated
  point-to-multipoint/wireless local loop (WLL)
  systems using PHS technology as the WLL
  component.
• the systems provide a completely wireless
  implementation between the local exchange and the
  subscriber telephone over very long distances.
• PHS was originally designed
• to offer enhanced wireless telephony services
  with limited mobility in urban and suburban areas
• In recent years, it has been deployed as a fixed
  wireless local loop solution.

21
Personal Handy Phone (PHP) Technology 3

• The main features of PMP/PHS-WLL are as follows
• end-to-end wireless access solution
• large service area of up to 540 km in a chain of
  repeaters
• flexible system capacity expandable to 1,400
  subscribers per base station
• high-quality service using 32 kbit/s ADPCM
  -robust against natural disasters
• low implementation and maintenance cost
• solar cells are available for repeater (80 W) and
  cell stations (40 W).

22
GMS400 Technology 1

• The European Telecommunications Standards
  Institute (ETSI) has established a regional
  standard for the implementation of the Global
  System for Mobiles (GSM) in the 400 MHz band.
• The use of frequencies in the 400 MHz band,
  rather than the 900/1800 MHz bands, enables a
  wider area to be covered by each base station.
  Wide area coverage is better suited to low
  density rural populations spread over a wide
  area.
• According to information submitted to the ITU by
  Ericsson,
• GSM 400 covers the same area as GSM 900 using
  approximately half the number of cell sites.
• A typical cell in the 400 MHz band has a 40 km
  radius when using 2-watt mobile phone units.
• Using higher gain or directional antennas, or
  with mobile phones of a higher power class, a
  longer range can be achieved depending on the
  geography and propagation conditions.

23
GMS400 Technology 2

• GSM 400 systems are expected to have the
  capabilities to extend the range of both voice
  and high-speed data coverage in comparison to
  existing GSM systems.
• The specifications for GSM 400 include
• support for GSM Phase 2 features such as General
  Packet Radio Service (GPRS),
• Enhanced Data for GSM Evolution (EDGE).
• GPRS is the first implementation of packet
  switching within GSM, allowing users to send and
  receive data at rates up to 115 kbit/s.

24
IMT-2000 Technology 3

• The ITU envisioned IMT-2000 with a number of
  features that would lower equipment costs by
• Specifying a highly modular design enabling
  incremental network investment
• Establishing well-defined radio and network
  interfaces to allow full interoperability of
  equipment from different manufacturers
• Creating a global market to realize economies of
  scale. In addition, there have been a number of
  steps taken specifically for the benefit of
  developing countries

25
IMT-2000 Technology 1

• The cellular base stations of the IMT-2000
  systems
• operating around 2 GHz provide a radius of
  coverage somewhat comparable to other digital
  cellular systems in the 1800-1900 MHz range.
• Supporting the evolution of first and second
  generation systems and recognizing that the cost
  to cover sparsely populated rural areas would be
  less expensive with larger cell sizes, WRC-2000
  identified additional spectrum for IMT-2000 under
  1 GHz, Region 1 (862-960), Region 2
  (806-892/928-960), Region 3 (610-960) MHz
  (Resolution 224 WRC-2000).

26
IMT-2000 Technology 2

• WRC-2000 approved the use of High Altitude
  Platforms (HAPS), at an altitude of 20 to 50 km,
  as base stations within the terrestrial component
  of IMT-2000 in the 2 GHz bands (Resolution 221).
• HAPS, as they are known, can potentially be used
  to provide service to a large footprint together
  with a dense coverage.
• The resolution specifies operating parameters to
  ensure that
• such base stations do not cause cochannel
  interference in neighboring countries,
• the development of appropriate regulatory
  provisions for coordination with the countries
• There are many opportunities for the application
  of IMT-2000 technologies to improve universal
  access in rural, remote, and underdeveloped areas
  of developing countries

27
VSAT Technology 1

• Very Small Aperture Terminals (VSATs) are playing
  a growing role in the provision of telephony,
  distance education, and data services in remote
  areas.
• VSATs are small satellite communication earth
  stations, typically less than 5-6 m in diameter.
• They can be installed directly at the user
  premises and left unattended.
• Due to falling equipment prices and the large
  footprint offered by communications satellites,
• VSATs are being deployed in areas where
  terrestrial telecommunication infrastructure is
  either uneconomical or too difficult to install.

28
VSAT Technology 2

• Prices for VSATs have fallen rapidly over the
  past decade, allowing manufacturers to expand
  sales of VSAT systems into low-end applications
  such as rural telephony.
• In addition to remote terminals, many VSAT
  network configurations employ a Master Hub,
  consisting of
• a large earth station antenna,
• network management facilities and
• associated systems.

29
VoIP Technology 1

• It is technologically possible, using available
  products, to establish an access network in rural
  and remote areas using routing technology rather
  than circuit-switched local exchanges.
• When combined with wireless technology in the
  local loop, such a network may provide an
  affordable solution for rural areas, particularly
  when the primary services delivered over the
  network will employ multimedia.

30
VoIP Technology 2

• Router-based local access networks using TCP/IP
  in the network and transport layers (OSI layers 3
  and 4) can be interconnected with the public
  switched telephone network using gateways that
  comply with ITU-T Recommendation H.323.
• Routers have been installed with wireless access
  technology in rural areas of developing
  countries, typically for the provision of
  Internet access in schools and businesses where
  wireline infrastructure is unavailable.