Wide-area and Personal-area Communications 23
Chapter 3
wireless-enabled products, and Developing Practical Wireless Applications explores in some
detail the existing and emerging new wireless technologies, coupled with the myriad of
applications that occupy and impress upon our personal and working environments.
In the following sections we appraise the generations of more established wireless
technologies and it will naturally provide a complete picture of the historical genera-
tion of wide- and personal-area, whilst molding a comparable impression of the over-
lap created between them. It is becoming more evident that manufacturers integrate
new wireless technology into cellular phones, notebooks and so on, resulting in the
overlap of wide-area and personal-area communications (see Figure 3.4). It is this
overlap that bestows the mobility and freedom characteristics of our personal and
working environments.
Generations of Wireless Technology
Undoubtedly, many of us have witnessed the emergence of generations of wide-area
technologies each depicting the advancement of applications and digital capability.
Regularly we read in the technology news, the relentless press releases announcing
faster and better applications that now rely on 3G technology (more about this later).
Perhaps the label of old seems somewhat inappropriate, as the more established gen-
erations of the wide-area era are growing at a phenomenal rate. The depiction of
wide-area communications helps us understand clearly where the respective technol-
ogies lie within the realm of personal-area emerging technologies, as we have concep-
tualized in Figure 3.5 (data rate vs. distance).
First Generation (1G)
First generation (or 1G) cellular telecommunications were only capable of supporting
voice traffic. Whats more, they were very susceptible to interference and offered no
security (eavesdroppers with basic radio equipment could listen in on conversations).
It has been reported that data traffic could occur, although “ideal” network conditions
were required, perhaps something similar to, the wind blowing in your hair and the sun
shinning on your face! 1G was introduced in the early 1980s and was based upon an
analog system comprising Frequency Modulation (FM), Frequency Division Duplex
(FDD) and Frequency Division Multiple Access (FDMA). Combining these primary
methods of radio transmission and reception, several variants of the first cellular tech-
nologies emerged to include the Advanced Mobile Phone Standard (AMPS), Total Access
Communication System (TACS) and the Nordic Mobile Telephony (NMT); these variants
24 Developing Practical Wireless Applications
were widely based in North America, Japan and Europe and became the most popular
and first commercially available cellular systems.
Understanding how FDMA works
FDMA offers a radio spectrum that is divided into channels, where typically each
channel is 30kHz; there is also a separate control channel, which is used to manage
and coordinate voice channel assignment. The reference to a channel within the
FDMA rationale is in fact two 30kHz channels: one for each direction, known as
uplink (or reverse channel) and downlink (or forward channel). This two-way strategy
is known as FDD and typically you will come across 1G technology being referred to
as FDMA/FDD. FDMA/FDD is a narrowband telecommunications system, which
implies that the available spectrum is divided into narrow radio channels, along with
a channel separator that is used to separate the uplink and downlink communication
pathway (primarily to reduce the likelihood of interference). When a cellular phone
initiates a call, a frequency channel is reserved for the duration of that call; frequency
modulation is then used to modulate voice data within the reserved frequency band.
Figure 3.5
The conceptual
presentation of
data rates versus
distance
illustrating the
placement of wide-
and personal-area
wireless
technologies.

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