ict in agriculture - Commonwealth Telecommunications Organisation

SECTION 1 — OVERVIEW OF ICT IN AGRICULTURE: OPPORTUNITIES, ACCESS, AND CROSS-CUTTING THEMES 23
BOX 2.3: Balancing Quality and Service in Reaching Rural
Areas: Fixed-line versus Wireless Backhaul
Even though wireless is accepted as an economical
option for delivering “last mile” connectivity, backhaul
traffic is usually carried via fiber-optic networks because
of their high capacity. Connectivity is often limited by the
limited penetration of the fixed-line backhaul that supports
it. The delivery of connectivity to rural areas lacking
fixed-line backhaul involves balancing concerns about
ICT access, connection quality, and the expenditures
and delays entailed in rolling out fixed lines and supporting
infrastructure. The benefits of wireless backhaul
technology are worth considering in such cases.
Wireless backhaul is increasingly recognized as an
option for combating the expenditures involved in providing
fixed-line rural connectivity. Wireless network
backhaul solutions can take the form of point-to-point
or point-to-multipoint wireless Ethernet bridges or wireless
mesh networks. They can use licensed or unlicensed
microwave links (see Unlicensed Wireless Use).
With throughput from as low as 10 Mbps up to GigE
full duplex (with gigabit wireless), a licensed microwave
link or wireless bridge can provide sufficient capacity for
many rural applications. Because it is compatible with
mobile phone standards (GSM, CDMA), the WiMAX
standard offers opportunities for rolling out affordable
wireless rural backhaul. Advocates of the technology are
optimistic about its potential for linking wireless fixedlocation
base stations to the core network.
Source: Authors.
Note: Mbps = megabit per second; GigE = Gigabit Ethernet; GSM =
Global System for Mobile Communication; CMDA = Code Division Multiple
Access (CDMA) 2000, a wireless air interface standard; WiMAX =
Worldwide Interoperability for Microwave Access.
made up of telephone lines, fiber-optic cables, microwave
transmission links, mobile networks, communications satellites,
and undersea telephone cables.
The difference between the two kinds of networks lies in
their switching mechanisms. Under circuit switching, the
connection is established on a predetermined, dedicated,
and exclusive communication path for the whole length of
the communication session. Consequently, PSTN connectivity
is costly. In packet-switching protocols, such as IP, the
communicated data are broken into sequentially numbered
packets, each of which is transmitted to the destination via
an independent path, and then the packets are reassembled.
In packet-switching, the potential for congestion, packet loss,
ECONOMIC AND SECTOR WORK
and delay can mar the quality of the connection. A comparison
between traditional fixed-line telephone services and voice
over IP (VoIP) clearly demonstrates the difference between
the two types of networks. NGNs completely separate the
packet-switched transport (connectivity) layer and the service
layer, enabling any available fixed-line carriage infrastructure
to be used efficiently for any service.
Domestic Backbone and Rural Backhaul Connectivity
As end users’ demand for additional bandwidth grows, insufficient
domestic backbone can pose a considerable challenge
to the roll-out of fixed-line broadband services. In the
mobile sector, insufficient backhaul capacity is becoming a
limitation, particularly with the increase of rural 3G data use.
Government interventions in support of rural backhaul solutions
have included the introduction of public-private funding
mechanisms (as in Korea and Chile; see box 2.4), construction
subsidies (as in Canada), and the rollout of fiber-optic
networks connecting public institutions (Rossotto et al. 2010).
Complementary regulations can be used to ensure competitive
conditions in the provision of domestic backbone and rural
backhaul. The policy tools for supporting domestic backbone
rollout and rural backhaul connectivity include infrastructure
sharing, 10 functional separation, 11 and cross-ownership restrictions,
allowing for interplatform competition12 ( Dartey 2009).
Local Loop or “Last Mile” Connectivity
The delivery of network access in the “last mile” is the most
costly and challenging element of rural deployments. The
technology options for delivering wired local loop broadband
connectivity include the rollout of xDSL, 13 cable, and fiber to
the home infrastructure. Wireless options include the rollout
of mobile (2G, 3G, 4G), 14 wireless broadband (WiMAX, Wi-Fi,
10 “Infrastructure sharing” is a mechanism for reducing capital
expenditures and operating expenditures. Passive infrastructure
sharing consists of colocating competitors. Active infrastructure
sharing consists of sharing the network base station controllers,
both circuit-switched and packet-oriented domains, mobile services
switching center, GPRS support node, and so on.
11 In “functional separation,” an incumbent operator is required to
establish separate divisions for managing fixed-line services and
providing wholesale services to retail competitors.
12 Cross-ownership restrictions prevent operators, such as telephony
operators, to control competitive network infrastructure,
such as cable television networks. For example, restrictions may
be placed on the simultaneous control of telephony and cable
television network infrastructures in a specified area.
13 xDSL refers to all digital subscriber line (DSL) technologies.
14 2G mobile wireless has basic functionality: voice and short messaging
service (SMS); 3G has advanced functionality: general
packet radio service; and 4G has broadband functionality: longterm
evolution (LTE).