Nowadays, network technology plays a significant role in the science and business area. Scientists innovate and develop some new technologies to fit businesses’ needs and to satisfy people’s demands. Thus, the hot topics of the network technology that are going to be illustrated in this paper are 3G and 4G technologies and beyond (5G). First of all, we have to know what 3G is. 3G means the third generation of wireless technology including several features, which are “enhanced roaming, broadband data services with video and multimedia, superior voice quality, up to 2M bit/sec and data always-on ([1], p.2318). In other words, 3G is a standard, common consensus with the features, developed and innovated by researchers and developers. In 2005, 3G is getting ready to live up to its performance in computer networking (WCDMA *1, WLAN *2 and Bluetooth *3) and mobile devices area (cell phone and GPS *5). The question is that 3G is not fully arrived yet; why people begin the discussion of 4G and even 5G. Is 4G the evolution or revolution from 3G? “There is no such thing as 4G; there’s just what’s beyond 3G, said Ronny Haraldsvik, vice president of marketing and global communications for Flarion Technologies ([8], p.43). Mikko A. Uusitalo, WWRF *6 chairman and head of international cooperation at Nokia Research Center, points out, “4G is a research item for next-generation wide-area cellular radio, where you have 1G, 2G, 3G and then 4G [and 5G] is the clear follow-up to that ([11], p. 36). From these points of view, we can clearly understand that 4G does not really exist yet. Generally speaking, 4G is an evolution not only to move beyond the limitations and problems of 3G, but also to enhance the quality of services, to increase the bandwidth and to reduce the cost of the resource [7]. Therefore, in the following sections, I focus on the time-line of the G evolution, the differences between 3G and 4G, 4G working principle, and 5G (completed wireless communication with almost no limitation; somehow people called it REAL wireless world).
Time-line from 1G to 4G and beyond:
Before discussing the deeper technical concepts, I want to show you how 4G develop from 1G. The first generation, 1G wireless mobile communication systems, was introduced in the early 1980s and completed in the early 1990s. 1G wireless was analog and supported the first generation of analog cell phones with the speeds up to 2.4kbps. The second generation, 2G system, fielded in the late 1980s and finished in the late 1990s, was planned mainly for voice transmission with digital signal and the speeds up to 64kbps. The third generation, 3G wireless system, was developed in the late 1990s and might be well-done in the late 2000s. 3G is not only provided the transmission speeds from 125kbps to 2Mbps, but also included many services, such as global roaming, superior voice quality and data always add–on. The fourth generation (4G) is a conceptual framework and a discussion point to address future needs of a high speed wireless network that can transmit multimedia and data to and interface with wire-line backbone network perfectly just raised in 2002. The speeds of 4G can theoretically be promised up to 1Gbps. The beyond will be 5G with incredible transmission speed with no limitation for access and zone size.
The main distinguishing factors between 3G and 4G will be data rates, services, transmission ways, access technology to the Internet, the compatibility to interface with wire-line backbone network, quality of service and security. According to the article, “WCDMA and WLAN for 3G and beyond, Harri Honkasalo, the director of IPR for Nokia Corporation, states that “4G should support at least 100 Mbps peak rates in full-mobility wide area coverage and 1Gbps in low-mobility local area coverage ([7], p. 18). The speeds of 3G can be up to 2Mbps, which is much slower than the speeds of 4G. For the service, 3G marketing is difficult to roam globally and interoperate across networks, yet 4G will be a global standard that provides global mobility and service portability so that service provider will no longer be limited by single-system [3]. In other words, 4G should be able to provided very smooth global roaming ubiquitously with lower cost. Furthermore, 3G is based on a wide-area concept applying circuit and packet switching for transmission with limited access technology, such as WCDMA, CDMA and TD-SDMA [2][4][5]. However, the 4G standard will base on broadband IP-based *8 entirely applying packet switching method of transmission with seamlessly access convergence [3][4][6][9]. It means that 4G integrated all access technologies, services and applications can unlimitedly be run through wireless backbone over wire-line backbone using IP address. In the other words, 4G will bring us almost perfect real world wireless or called “WWWW: World Wide Wireless Web ([1], p. 2321). The most interesting questions are how researchers and developers make 4G such a powerful standard and how 4G is manipulated and implemented. Therefore, next section is focused on what technologies are used in 4G demonstrating its working theories.
How 4G works (working principle):
In the 4G wireless networks, each node will be assigned a 4G-IP address (based on IPv6), which will be formed by a permanent “home IP address and a dynamic “care-of address that represents its actual location [1]. When a device (computer) in the Internet wants to communicate with another device (cell phone) in the wireless network, the computer will send a packet to the 4G-IP address of the cell phone targeting on its home address. Then a directory server on the cell phone’s home network will forward this packet to the cell phone’s care-of address through a tunnel, mobile IP; moreover, the directory server will also inform the computer that the cell phone’s care-of address (real location), so next packets can be sent to the cell phone directly. The idea is that the 4G-IP address (IPv6) can carry more information than the IP address (IPv4) that we use right now. IPv6 means Internet Protocol Version 6 including 128 bits, which is 4 times more than 32bits IP address in IPv4. 32 bits IP address looks like this 216.37.129.9 or 11011000.00100101.10000001.00001001 (32 bits). However, the IP address in IPv6 version will be 4 times of IPv4; it looks like 216.37.129.9, 79.23.178.229, 65.198.2.10, 192.168.5.120. It includes 4 sets of IPv4 address defined in different functions and usages. In previous example for the case, the first set of the IP address (216.37.129.9) can be defined to be the “home address purpose. It just likes the normal IP address that we use for addressing in the Internet and network. The second set of the IP address (79.23.178.229) can be declared as the “care-of address. It is the address set up for the communication from cell phones to computers. After these addresses from cell and PC established a link, care-of address will instead of home address; it means that communication channel will switch from the first set to the second set of the IPv6 address. The third set of the IP address (65.198.2.10) can be signed as a tunnel (mobile IP address). It is the communication channel to wire-line network and wireless network. An agent, a directory sever, between the cell phones and PC will use this mobile IP address to establish a channel to cell phones. Then, the last set of IP address (192.168.5.120) can be local network address for virtual private network (VPN) sharing purpose. In this rich data IP address, software can use them to distinguish different services and to communicate and combine with other network areas, such as computer (PC) and cell phones’ network in the case of the example. In addition, the table bellow is a basic comparison of IPv6 and IPv4 showing that how IPv6 richer than IPv4 in data containing capacity. Moreover, in 4G wireless network, not only has it IPv6 transmission protocol, but also be supported by OFDM, MC-CDMA, LAS-CDMA, UWB *7 and Network-LMDS.
OFDM stands for Orthogonal Frequency Division Multiplexing, transmitting large amounts of digital data over a radio wave. OFDM works by splitting the radio signal into multiple smaller sub-signals that are then transmitted simultaneously at different frequencies to the receiver. In the other words, OFDM is a digital modulation technology in which in one time symbol waveform, more than thousands of orthogonal waves are multiplexed for increasing signal strength. This is good for high bandwidth digital data transition. The picture bellow is another example to explain how OFDM works for signal enhancement. In this case, people might have a question about how radio wave targeted the correct destination. In OFDM, two wireless devices will establish a connection tunnel before they start their communication. Therefore, after making a connection between a certain target, the radio signal will split into many smaller sub-signals with accurate direction to the target; that is why the red lines in the bellow picture have the same direction to their destination (a laptop).
MS-CDMA stands for Multi-Carrier Code Division Multiple Access, which is actually OFDM with a CDMA overlay. The users are multiplexed with orthogonal codes to distinguish users in MS-CDMA and single-carrier CDMA systems. It allows flexible system design between cellular system and signal cell system. However, in MC-CDMA, each user can be allocated several codes, where the data is spread in time or frequency.
LAS-CDMA, Large Area Synchronized Code Division Multiple Access, is developed by LinkAir Communication, a patented 4G wireless technology. “Las-CDMA enables high-speed data and increases voice capacity and the latest innovative solution, Code-Division Duplex (CDD), merges the highly spectral efficient LAS-CDMA technology with the superior data transmission characteristics of Time-Division Duplex (TDD). This resulting combination makes CDD to be the most spectrally efficient, high-capacity duplex system available today ([1], p. 2319). In the 4G area, LAS-CDMA is played as a global transmission protocol (“World Cell) as showing in the following picture, Zone size ([12], p.30). It means that if the distance is too far to two wireless devices, they have to use this protocol with IPv6 to establish their connection.
In 4G technologies, UWB *7 radio can help solve the multi-path fading issues by using very short electrical pulses to across all frequencies at once. However, UWB can only be used indoor or underground because of its low-power requirement. Thus, UWB has to be used with OFDM, which can transmit large among of digital data with multi-path algorithm; OFDM running outdoor, UWB running indoor to ensure signal strength purpose. In the 4G wireless technology, UWB will be played as “Pico Cell for very limited distance in the buildings.
The Network-LMDS, Local Multipoint distribution system, is the broadband wireless technology used to carry voice, data, Internet and video services in 25GHz and higher spectrum. Its broadcast method consisted simultaneous voice, data, Internet, and video traffic can be the solution of signal fading issue in local area. Therefore, Network-LMDS can be played as Micro Cell and Macro Cell in the 4G technology to be the main transmission protocol for the wireless devices, showing as the picture below.
The idea of the complementation of IPv6, OFDM, MC-CDMA, LAS-CDMA, UWB and Network-LMDS can be arranged in different zone size. IPv6 can be designed for running in the all area because it is basic protocol for address issue. LAS-CDMA can be designed for the global area as zone 1, world cell. OFDM and MC-CDMA can be designed for running in the wide area (Zone 3), called Macro cell. Network-LMDS is in Zone 2, Micro cell, and UWB is in Zone 1, Pico cell [12]. Based on above transmission protocol, we knew that each of them has its drawback(s) in somewhere; although the complementation with all of them, it is not perfect yet to implement 4G’s great idea. Academic research and experiments are still required for further developing of 4G in the following few to 10 years.
5G (Real wireless world) (completed WWWW: World Wide Wireless Web):
The idea of WWWW, World Wide Wireless Web, is started from 4G technologies. The following evolution will based on 4G and completed its idea to form a REAL wireless world. Thus, 5G should make an important difference and add more services and benefit to the world over 4G; 5G should be a more intelligent technology that interconnects the entire world without limits.
Conclusion:
Nowadays, wireless technology is getting popular and important in the network and the Internet field. In this paper, I briefly introduced the history background of 1G to 5G, compared the differences of 3G and 4G, and illustrated how 4G may work for more convenient and powerful in the future. 4G just right started from 2002 and there are many standards and technologies, which are still in developing process. Therefore, no one can really sure what the future 4G will look like and what services it will offer to people. However, we can get the general idea about 4G from academic research; 4G is the evolution based on 3G’s limitation and it will fulfill the idea of WWWW, World Wide Wireless Web, offering more services and smooth global roaming with inexpensive cost.
Summary:
The first generation, 1G wireless mobile communication systems, was analog and the speeds up to 2.4kbps introduced in the early 1980s and completed in the early 1990s. The second generation, 2G system, fielded in the late 1980s and finished in the late 1990s, was digital signal for voice and the speeds up to 64kbps. The third generation, 3G wireless system, was provided the transmission speeds from 125kbps to 2Mbps developed in the late 1990s and might be well-done in the late 2000s. The fourth generation (4G) does not really exist yet. Basically speaking, 4G is an evolution to move beyond the limitations and problems of 3G. The speeds of 4G can theoretically be promised up to 1Gbps. The beyond will be 5G with incredible transmission speed with no limitation for access and zone size.
The differences between 3G and 4G are data rate (speeds), service, for example global roaming, interface with wire-line Internet, QoS and security. 4G will be supported by IPv6, OFDM, MC-CDMA, LAS-CDMA, UWB and Network-LMDS. They can be arranged in different zone size. IPv6 can be designed for running in the widest zone, called World cell. OFDM, MC-CDMA and LAS-CDMA can be designed for running in the wide area, called Macro cell. Network-LMDS is in Micro cell, and UWB is in Pico cell. In the 4G wireless networks, each node will be assigned a 4G-IP address (based on IPv6, 128 bits), which will be formed by a permanent “home IP address (32 bits) and a dynamic “care-of address (32 bits) that represents its actual location. The care-of address will be informed to other devices by directory server for directly transmit purpose using mobile IP interface with wire-line network and wireless network.
5G will be the completed version of WWWW, World Wide Wireless Web, to form a real wireless world with no more limitation with access and zone issue.
Glossaries:
<1> WCDMA: Wide-band Code-Division Multiple Access, a 3G technology that increases data transmission rates in GSM systems by using the CDMA air interface instead of TDMA. WCDMA is based on CDMA and is the technology used in UMTS.
<2> WLAN: Wireless Local-Area Network. A type of local-area network that uses high frequency radio waves rather than wires to communicate between nodes.
<3> Bluetooth: A short-range radio technology aimed at simplifying communications among Internet devices and between devices and the Internet.
<4> GIS: Geographic Information Systems, tools used to gather, transform, manipulate, analyze, and produce information related to the surface of the Earth. The data may exist as maps and 3D virtual models.
<5> GPS: Global Positioning System, a worldwide MEO satellite navigational system formed by 24 satellites orbiting the Earth and their corresponding receives on the Earth.
<6> WWRF: Wireless World Research Forum, to formulate strategic visions on future research directions in the mobile and wireless area; to generate, identify and promote technical trends for mobile and wireless systems technologies; to enable global R&D collaboration.
<7> UWB: Ultra Wide Band, a wireless communication technology that can currently transmit data at speeds between 40 to 60 mbps and eventually up to 1Gbps. UWB transmits ultra-low power radio signals with very short electrical pulses (1/1000th of a nanosecond) across all frequencies at once. UWB is very difficult to detect because of low power requirements; hence, difficult to regulate. It can be used indoors and underground unlike GPS.
<8> Broadband: A type of data transmission in which a single medium (wire) can carry several channels at once. Cable TV, for example, uses broadband transmission. In contrast, base-band transmission allows only one signal at a time.
<9> ATM: Asynchronous Transfer Mode, a high speed transmission protocol in which data blocks are broken down into small cells that are transmitted individually and possibly via different routes in a manner similar to packet switching. ATM is a form of data transmission, which allows voice, video and data to be sent on the same network.
<10> GSM: Global System for Mobile Communications, one of the leading digital cellular systems. GSM uses narrowband TDMA, which allows eight simultaneous calls on the same radio frequency. GSM was first introduced in 1991. As of the end of 1997, GSM service was available in more than 100 countries and has become the de facto standard in Europe and Asia.
<11> GPRS: General Packet Radio Service, a standard for wireless communications which runs at speeds up to 115Kbps, compared with current GSM system’s 9.6Kbps. GPRS, which supports a wide range of bandwidths, is an efficient use of limited bandwidth and is particularly suited for sending and receiving small bursts of data, such as email and web browsing, as well as large volumes of data.
<12> UMTS: Universal Mobile Telecommunications System, a 3G mobile technology that will deliver broadband information at speeds up to 2Mbps. Besides voice and data, UMTS will deliver audio and video to wireless devices anywhere in the world through fixed wireless and satellite systems.
<13> ITU: International Telecommunication Union, an international organization through which public and private organizations develop telecommunications. The ITU was founded in 1865 and became a United Nations Agency in 1947. it is responsible for adopting international treaties, regulations and standards governing telecommunications. The standardization functions were formerly performed by a group with the ITU called CCITT, but after 1992 reorganization the CCITT no longer exists.
<14> TDMA: Time Division Multiple Access, a technology for delivering digital wireless service using time-division multiplexing (TDM). TDMA works by dividing a radio frequency into time slots and then allocating slots to multiple calls. In this way, a single frequency can support multiple, simultaneous data channels. TDMA is used by the GSM digital cellular system.