What This Book Is About 3
to 802.11b/g/n and bandwidths rated up to 1300 Mbps on the 5 GHz band,
plus up to 450 Mbps on 2.4 GHz. In addition to these four Wi-Fi standards,
other related wireless network technologies have to share the same 2.4 GHz
ISM band. Bluetooth, for example, uses 2.4 GHz. Bluetooth supports a very
short range of up to 10 m and relatively low bandwidth of 1 Mbps. It is used in
low-power network devices such as medical devices, wireless keyboards and
mouses, and handhelds. Other than 5 and 2.4 GHz ISM bands, many other
bands are used for machine-to-machine wireless connectivity solutions. Some
of the most used ISM bands around the world are 315 and 915 MHz in the
United States; 187, 230, 433, and 868 MHz in Europe; 426, 429, 449, 950, and
1200 MHz in Japan; and 223, 230, 315, and 433 MHz in China. These devices
are generally deployed in cost-sensitive consumer products such as garage
door openers, remote keyless entry, toys, and remote controllers. Mobile cel-
lular networks also consume a significant amount of spectral resources due
mainly to the number of active users at a given time. Initial forms of cellular
networks were used to deliver voice-only data through analog modulation;
hence, the sound quality was poor and the speed of transfer was only at
9.6 Kbps. With the advance of 2G networks, the transmission quality had im-
proved by introducing the concept of digital modulation. 2.5G is a transition
between 2G and 3G. In 2.5G, the most popular services, like Short Message
Service (SMS), General Packet Radio Service (GPRS), Enhanced Data for GSM
(Global System for Mobile Communication) Evolution (EDGE), and more,
had been introduced. Shortly after the introduction of 2.5G systems, the 3G
generation of mobile telecommunication standards had emerged. It allows
simultaneous use of speech and data services and offers data rates of up to
2 Mbps, which provide services like video calls, mobile TV, mobile Internet,
and downloading. There are many technologies that fall under 3G, like Wide-
band Code Division Multiple Access (WCDMA) and High Speed Package
Access (HSPA). In telecommunications, 4G is the fourth generation of cellular
wireless standards. It is a successor to the 3G and 2G families of standards. In
2008, the ITU-R (International Telecommunication Union Radiocommunica-
tion Sector) organization specified the IMT-Advanced (International Mobile
Telecommunications Advanced) requirements for 4G standards, setting data
transfer requirements for 4G service at 100 Mbit/s for high-mobility commu-
nication, such as from trains and cars, and 1 Gbit/s for low-mobility commu-
nication stationary users. A 4G system is expected to provide a comprehensive
and secure all-(Internet Protocol) IP-based mobile broadband solution to lap-
top computers, wireless modems, smartphones, and other mobile devices.
New services such as ultra-broadband Internet access, IP telephony, gaming
services, and streamed multimedia may be provided to users. Early 4G tech-
nologies such as mobile WiMAX and Long-term Evolution (LTE) have been
aroundfor a while. The current versions of these technologies did not fulfill the
original ITU-R requirements of data rates approximately up to 1 Gbit/s for 4G
systems. Another wireless communication field is GPS. All satellites broad-
cast at the same two frequencies, 1.57542 GHz (L1 signal) and 1.2276 GHz