Cellular Phones as Embedded Systems

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I. INTRODUCTION
A. Market development
In the 1990s wireless technologies developed in a way that can best
be described as 'unbelievable'. Consequently, the number of mobile
subscribers has grown over 100-fold in the last ten years, as shown
in Figure 1. Currently, there are over one billion subscribers globally
and the number is growing at a healthy pace. Current scenarios
predict another 400 million subscribers by 2005, leading to a
total of some 1.6 billion subscribers. Continuing with scenarios for
mobile voice, there is also a big opportunity in the growth of mobile
traffic as fixed voice calls are increasingly being replaced by mobile
calls. By 2008, there is a good chance that the current number of
global mobile subscriptions will double.


B. Cellular generations
Radio systems continue to develop from the current second generation
(2G) and evolved 2G systems toward higher data rates and
better mobility. While the third-generation ([1]-[6]) cellular system
is being rolled out and the first terminals have reached the
shops in Japan and Europe, standardization work continues
towards even higher data rates. Several access methods complement
3G, e.g. the wireless local area network for high-speed hot
spot data connection and Bluetooth for short-range radio connection.
Furthermore, discussions and research on the next-generation
cellular system, 4G, have already started [7]. 4G is expected
to enable versatile mobile broadband services by providing wide
coverage, ultra-high bit-rate radio access. In the multiradio environment,
the services are required to be radio-agnostic. This is
best achieved by utilizing the Internet protocol (IP) convergence as
the unified connection layer


C. Digital convergence
The digital industry is experiencing rapid convergence of parts of
consumer electronics, communication, information technology,
media and entertainment industries. The convergence enables
people to create, share, and consume digital content using interoperable
devices. The cellular phone, the main device that people
always carry with them, is the key platform for the mobile convergence
applications, e.g. web browsing, imaging, and high bitrate
video streaming. Mobility means that the mobile Internet will
bring us new features to facilitate the way we live and work


II. TODAY’S CELLULAR PHONE
Cellular phones are extremely complex embedded systems where
all functional blocks are custom-made for mobility. The combination
of miniaturization and functionality is unprecedented compared
to other consumer products. A block diagram of today’s typical
classic category triple-band cellular phone is shown in Figure
3. The engine consists of three main chips: one for RF, one for
baseband, and one for mixed-signal and energy management. The
chips are either proprietary designs or based on available chip
sets. The product includes a total of 345 parts. The characteristics
of the cellular phone shown in Figure 3 are represented in Table I.

III. ARCHITECTURE CHALLENGES FOR WIRELESS
ACCESS
New implementation architectures enable the adoption of new
technologies. The new technologies, then, bring improvements in
product requirements, such as performance, miniaturization,
power consumption, reliability and cost. Several successful
development phases in the past laid the foundation for improvements
also in the future.