The fourth and fifth generation wireless mobile systems, commonly known as 4G and 5G, are expected to provide global roaming across different types of wireless and mobile networks, for instance, from satellite to mobile networks and to Wireless Local Area Networks (WLANs). 4G is an all IP-based mobile network using different radio access technologies providing seamless roaming and providing connection always via the best available network . The vision of 4G wireless/mobile systems is the provision of broadband access, seamless global roaming, and Internet/data/voice everywhere, utilizing for each the most “appropriate” always best connected technology . These systems are about integrating terminals, networks, and applications to satisfy increasing user demands (, ). 4G systems are expected to offer a speed of over 100 Mbps in stationary mode and an average of 20 Mbps for mobile stations reducing the download time of graphics and multimedia components by more than 10 times compared to currently available 2 Mbps on 3G systems. The fifth generation communication system is envisioned as the real wireless network, capable of supporting wireless world wide web (wwww) applications in 2010 to 2015 time frame. There are two views of 5G systems: evolutionary and revolutionary. In the evolutionary view the 5G (or beyond 4G) systems will be capable of supporting wwww allowing a highly flexible network such as a Dynamic Adhoc Wireless Network (DAWN). In this view advanced technologies including intelligent antenna and flexible modulation are keys to optimize the adhoc wireless networks. In revolutionary view 5G systems should be an intelligent technology capable of interconnecting the entire world without limits. An example application could be a robot with built-in wireless communication with artificial intelligence. The 4G system is still predominantly a research and development initiative based upon 3G, which is struggling to meet its performance goals. The challenges for development of 4G systems depend upon the evolution of different underlying technologies, standards, and deployment. We present an overall vision of the 4G features, framework, and integration of mobile communication. First we explain the evolutionary process from 2G to 5G in light of used technologies and business demands. Next we discuss the architectural developments for 2G-5G systems, followed by the discussion on standards and services. Finally we address the market demands and discuss the development of terminals for these systems.
2G–5G Networks: Evolution
The first generation of mobile phones was analog systems that emerged in the early 1980s . The second generation of digital mobile phones appeared in the 1990s along with the first digital mobile networks. During the second generation, the mobile telecommunications industry experienced exponential growth in terms of both subscribers and value-added services. Second generation networks allow limited data support in the range of 9.6 kbps to 19.2 kbps. Traditional phone networks are used mainly for voice transmission, and are essentially circuit-switched networks.
2.5G networks, such as General Packet Radio Service (GPRS), are an extension of 2G networks, in that they use circuit switching for voice and packet switching for data transmission resulting in its popularity since packet switching utilizes bandwidth much more efficiently. In this system, each user’s packets compete for available bandwidth, and users are billed only for the amount of data transmitted.
3G networks were proposed to eliminate many problems faced by 2G and 2.5G networks, especially the low speeds and incompatible technologies such as Time Division Multiple Access (TDMA)  and Code Division Multiple Access (CDMA)  in different countries. Expectations for 3G included increased bandwidth; 128 Kbps for mobile stations; and 2 Mbps for fixed applications . In theory, 3G should work over North American as well as European and Asian wireless air interfaces. In reality, the outlook for 3G is not very certain. Part of the problem is that network providers in Europe and North America currently maintain separate standards’ bodies (3GPP for Europe and Asia; 3GPP2 for North America). The standards’ bodies have not resolved the differences in air interface technologies. There is also a concern that in many countries 3G will never be deployed due to its cost and poor performance. Although it is possible that some of the weaknesses at physical layer will still exist in 4G systems, an integration of services at the upper layer is expected.
Key Terms in this Chapter
EDGE: Enhanced Data rates for Global Evolution technology gives GSM and TDMA the capability to handle third generation mobile phone services with speeds up to 384 kbps. Since it uses the TDMA infrastructure, a smooth transition from TDMA based systems such as GSM to EDGE is expected.
DSSS: In Direct Sequence Spread Spectrum, the data stream to be transmitted is divided into small pieces, each of which is allocated a frequency channel. Then the data signal is combined with a higher data rate bit sequence known as “chipping code” that divides the data according to a spreading ratio, thus allowing a resistance from interference during transmission.
1G: Old-fashioned analog mobile phone systems capable of handling very limited or no data at all.
3GPP: Third Generation Partnership Project. 3GPP is an industry body set up to develop a 3G standard based upon wideband CDMA (WCDMA).
DAWN: Advanced technologies including smart antenna and flexible modulation are keys to optimize this wireless version of reconfigurable ad hoc networks.
FHSS: In Frequency Hopping Spread Spectrum, a broad slice of bandwidth spectrum is divided into many possible broadcast frequencies to be used by the transmitted signal.
CDPD: Cellular Digital Packet Data is a wireless standard providing two way data transmission at 19.2 kbps over existing cellular phone systems.
CDMA: Code Division Multiple Access, also known as CDMA-ONE or IS-95, is a spread spectrum communication technology that allows many users to communicate simultaneously using the same frequency spectrum. Communication between users are differentiated by using a unique code for each user. This method allows more users to share the spectrum at the same time than alternative technologies.
3.5G: Interim systems between 3G and 4G allowing a downlink data rate upto 14 Mbps. Sometimes it is also called as High Speed Downlink Packet Access (HSDPA).
Ad-hoc Networks: A self configuring mobile network of routers (and hosts) connected by wireless, in which the nodes may move freely and randomly resulting in a rapid and unpredictable change in network’s wireless topology. It is also called a Mobile Ad-hoc NETwork (MANET).
2.5G: Interim hardware and software mobile solutions between 2G and 3G with voice and data capabilities and data rates ranging from 56 kbps to 170 kbps.
WAP: Wireless Application Protocol defines the use of TCP/IP and Web browsing for mobile systems.
Spread Spectrum: It is a form of wireless communication in which the frequency of the transmitted signal is deliberately varied over a wide range. This results in a higher bandwidth of the signal than the one without varied frequency.
5G: In an evolutionary view, it will be capable of supporting wwww allowing highly flexible dynamic ad hoc wireless networks. In a revolutionary view, this intelligent technology is capable of interconnecting the entire world without limits.
Bluetooth: A wireless networking protocol designed to replace cable network technology for devices within 30 feet. Like IEEE 802.11b, Bluetooth also operates in unlicensed 2.4GHz spectrum, but it only supports data rates up to 1 Mbps.
3GPP2: Third Generation Partnership Project 2. 3GPP2 is an industry standard set up to develop a 3G standard based upon CDMA-2000.
3G: A long awaited digital mobile systems with a maximum data rate of 2 Mbps under stationary conditions and 384 kbps under mobile conditions. This technology is capable of handling streaming video two way voice over IP and Internet connectivity with support for high quality graphics.
UMTS: Universal Mobile Telecommunications System is the third generation mobile telephone standard in Europe that was proposed by ETSI.
WDM: Wavelength Division Multiplexing allows many independent signals to be transmitted simultaneously on one fiber with each signal located at a different wavelength. Routing and detection of these signals require devices that are wavelength selective, allowing for the transmission, recovery, or routing of specific wavelengths in photonic networks.
GPRS: General Packet Radio Service provides data rates upto 115 kbps for wireless Internet and other types of data communications using packet data services.
2G: Second generation voice-centric mobile phones and services with limited data rates ranging from 9.6 kbps to 19.2 kbps.
Mobile Phones: Mobile communication systems that use radio communication and conventional telephone switching to allow communication to and from mobile users.
Photonic Networks: A network of computers made up using photonic devices based on optics. The devices include photonic switches, gateways, and routers.
TDMA: Time Division Multiple Access is a technology for sharing a medium by several users by dividing into different time slots transmitting at the same frequency.
GSM: Global Systems for Mobile Communication is a worldwide standard for digital wireless mobile phone systems. The standard was originated by the European Conference of Postal and Telecommunications Administrations (CEPT) who was responsible for the creation of ETSI. Currently, ETSI is responsible for the development of GSM standard.
WWWW: A World Wide Wireless Web is capable of supporting a comprehensive wireless-based Web application that includes full graphics and multimedia capability at beyond 4G speeds.
WCDMA: Wideband CDMA is a technology for wideband digital radio communications of multimedia and other capacity demanding applications. It is adopted by ITU under the name IMT-2000 direct spread.
4G: Planned evolution of 3G technology that is expected to provide support for data rates up to 100 Mbps allowing high quality and smooth video transmission.
PSTN: Public Switched Telephone Network is a regular voice telephone network.
CDMA-2000: Sometimes also known as IS-136 and IMT-CDMA multicarrier (1X/3X) is an evolution of narrowband radio transmission technology known as CDMA-ONE (also called CDMA or IS-95) to third generation. 1X refers to the use of 1.25 Mhz channel while 3X refers to 5 Mhz channel.