Wireless communication - Essay Example

The focus of this paper is to investigate the development of cellular phone systems since the inception of 1G, 2G, and 3G to the most recent 4G technologies. The paper also discusses the comparisons of the various techniques in terms of standards, data rates, multiplexing technology and core network among others. Unlike other previous forms of communication, wireless communication networks have increasingly gained popularity especially with the recent mode like 3G and 4G which have continuously improved data transfer and communication efficiency. Recent advances in technology have led to efficient satisfaction of the needs of consumers while ensuring that life is easier. The second generation GSM and its evolutional stages of GPRS and EDGE and third generation UMTS are discussed in detail to pave way in understanding the 4G technology. Wireless communication: 1G-4G cellular communication systems 1.0. Introduction Cellular mobile telephone systems development and deployment was triggered by the operational limitations of standard mobile telephone systems (Brand and Aghavami, 1). These limitations include limited capacity for service, inefficient utilization of spectrum and poor service performance. The communication of mobile phone occurs through a temporary distinct radio channel in order to communicate to the cell site. The cell site is contains several channels and each mobile talks to it through only one of the channels. The channels are characterized by a pair of frequencies which are used during the communication. The forward link transmits from the cell site to the users while the reverse link receives calls from users. The radio signal transmitted in early mobiles dissipated with distance and mobiles had to stay close to the base station in order to secure effective communications. According to Brand and Aghvami (1), moving mobile users were not sufficiently offered with an effective means of communication. Mobile radio service has its operations in a closed network with no access to the telephone system unlike the mobile telephone service that allowed interconnection to the telephone network. Traditionally, the mobile service structure included a single powerful transmitter that was located at a high spot to broadcast signals within a radius of up to about 50 km and the mobile telephones were attached to the transmitter (Brand and Aghvami, 2). Conversely, the introduction of cellular telephone system architecture involves placing numerous low-power transmitters within the entire coverage area and each covers a small area called the cell and using varying channels or conversions. The cellular telephone system allows a user to travel while making a phone call with no interruptions since they can use more than one base station. The application of the cellular concept in mobile telephone systems overcame interference problems and improved the efficiency of communication since the cells size was equivalent to the density and demand of subscribers in a particular area and was flexible to accommodate growing population’s demand and user density. Interference is overcame since a cluster can be reused in other cells while conversations can be handed off from one cell to the other and phone services maintained constantly as one moves between cells through handoff (Brand and Aghvami, 2). Cellular phone systems is characterized by four generations which are first generation or 1G, second generation or 2G, third generation or 3G and fourth generation or 4G. This paper explores cellular mobile system generations in terms of their capabilities, date of introduction, and comparison of inherent features. 2.0. First generation or 1G cellular phone systems The 1G cellular phone systems are characterized by the use of analog frequency modulation to facilitate the transmission of speech, frequency shift keying or FSK for signaling while FDMA or frequency Division Multiple Access for the sharing of assigned spectrum (Patil, Karhe and Aher, 614). The most popular 1G cellular phone systems developed around the world are the United States’ AMPS or Advanced Mobile phone service, the United Kingdom’s Total Access Communication System or TACS, Scandinavia’s Nordic Mobile Telephone, the Nippon Telephone and Telegraph or NTT and C450 (Patil, Karhe and Aher, 614). All 1G cellular phone systems utilize full duplex transmission where one frequency channel is from one base station or BS to the mobile station, MS while the other is from the MS to the BS (Brand and Aghvami, 2). The full duplex transmission signifies that in a two way connection, the two channels are used with the uplink and downlink channels being separated from each other by 45 MHz for AMPS and TACS, 10 MHz for C450 and NMT 450, and 55MHz for NTT. The separation distance was selected owing to its ability to utilize cheap extremely selective duplexers. The control channels named Forward Control Channels or FCC are used for transmission downlink while Reverse Control Channels, RCC, are utilized for uplink signal transmission (Godara, 1). 2.1. Date of introduction The introduction of the first generation cellular wireless mobile phones was established in America in 1978, Australia 1987 and Israel 1986 (Brand and Aghvami, 24). The introduction of 1G mobile communication was very significant given that the resulting mobile telephone service made use of smaller and lighter microprocessors, and technologically advanced mobile systems. By the end of 1990, 1G cellular phone systems was characterized by a market growth of up to 20 million subscribers. 2.2. Capabilities of 1G cellular wireless phone systems According to Patil, Karhe and Aher (614), first generation cellular networks were introduced with the intention of voice transmission. These networks were slow and transmitted less than one kilobit per second or kbps. For the 1G systems, cellular networks involves the division of a geographical area into small cells and each phone comprises of a serial number that is 32 bit while its Programmable Read Only Memory, PROM has a 10 digitphone number (Patil, Karhe and Aher, 614). The size of the cells is crucial for frequency reuse in the adjacent cells thereby providing constant coverage. The 1G cellular phone systems utilize frequency division duplexing or FDD/FDMA while the only standards used are Common Air Interface or CAI like Analog Voice Communications through Frequency Modulation, FM and Digital control channels for signaling. Since the 1G cellular mobile systems use analog technology, speech is transmitted in analog signals which raises security issues. For a person with an all-band radio receiver, the conversation in between analog cellular phones can be listened to or the all-band radio receiver can be used to steal airtime by connecting it to a computer which records the serial number and subscriber’s phone numbers (Brand and Aghvami, 24). The security issues and the slow data transmission rates led to the development of second generation systems. 3.0. Second generation or 2G cellular phones systems 3.1. Date of implementation Patil, Karhe and Aher (614) reveal that the second generation or 2G cellular phone system design was implemented in 1991 to make use of Time Division Multiple Access, TDMA or Code Division Multiple Access, CDMA access schemes and utilize digital transmission of data. The 2G cellular phone systems were intended for voice transmission that also supported fax and email services. The transmission rate was very low and was around 8-9 kbps but which was much higher than that of the 1G system (Patil, Karhe and Aher, 615). The main 2G system are North American dual-mode cellular system Interim Standard 54 or IS-54 and later became IS-136, North American IS-95 systems, Japanese Personal Digital Cellular or PDC and the European Global Systems for Mobile Communications or GSM and Digital Cellular System, DCS 1800 from Europe (Godara, 16). Except for the North American IS-95 or CdmaOne that uses CDMA and FDD, all other 2G cellular systems make use of TDMA and FDD systems. Godara points out that, in its capacity, the 2G wireless cellular systems have provided great improvements to the quality of voice and also established a basis on which value-added services in the coming days will be laid (16). 3.2. Capabilities of 2G wireless cellular systems 3.2.1. Global Systems for Mobile communications or GSM The GSM network involves communication between a mobile station or MS and a BSS or base station system. GSM communication occurs through air or radio interface (Godara, 17). The two main elements constituting the Mobile station are SIM or subscriber identity module smart card and ME or the mobile equipment. The radio link in GSM uses both FDMA and TDMA technology. The voice and slow circuit switched data services by GSM are upheld through BSS core network or CN to a user within the same network. The original GSM speed was 9.6 kbps which later became 14.4 kbits/s. however, GSM of 0.3 Gaussian minimum shift keying or GMSK modulation has 270.833kbps data rate (Patil, Karhe and Aher, 615). Today, GSM includes numerous forms of data services and teleservices. Examples of teleservices are emergency calling, teletext, videotext and facsimile. The most common data services are communication from one computer to the other and packet switched traffic. GSM is uniquely characterized by SIM which is distinct for each subscriber. 3.2.2. Interim standard 136(IS-136) or North American Digital cellular, NADC This standard supports time slotted users for each 30 KHz and utilizes time division multiple access and FDMA. For each time slot, there is one digital traffic channel or DTC that accommodates the user’s digitized speech and data (Patil, Karhe and Aher, 615). A time slot also has three supervisory channels responsible for transmitting control information. The rate of data is 46.6kbps in a channel of 60MHz bandwidth while the differential quardrature phase shift keying technique or DQPSK of modulation is used. This phase offered elevate signaling rate and included of point-to-point broadcast and short messages, addressing of groups and others (Patil, Karhe and Aher, 615). 3.2.3. Personal Digital cellular systems Established in Japan, PDC systems, like the IS-54, operated under TDMA technique with each frequency channel comprising of three time slots and 20ms time duration (Godara, 18). During operation, the PDC standard can support three users for full rate speech or six users at half rate speech. The technique uses ?/4 DQPSK or ?/4 Differential Quardrature Phase Shift Keying (Godara, 18). 3.2.4. Interim standard-95 or code division multiple access digital cellular system The multiple access technique used here takes up the same frequency band as AMPS and the forward link and reverse link separation is by 45 MHz. The modulation of signals in IS-95 is through binary phase shift keying or BPSK (Brand and Aghvami, 25). Despite 2G standard cellular phones being efficient in the provision of voice data transmission, their applications at internet browsing applications operate at very low speeds which means 2G standards are inefficient for high speed electronic mail or e-mail and this means they should be modified to 2.5G standard (Patil, Karhe and Aher, 615). 2G circuit switched standards include high-speed circuit-switched data or HSCSD, MLS or mobile Location services and wireless application protocols, WAP. A 2.5G standard uses General Packet Radio Service or GPRS where WAP which allows the compression of web pages for view by users (Patil, Karhe and Aher, 615). 4.0. Third generation or 3G cellular phone systems or mobile broadband data 4.1. Date of introduction 3G technologies were introduced in 2001 which was the beginning of the 21st century as a result of 3G global partnership projects for wideband CDMA standard or 3GPP and 3GPP2or 3G global partnership projects for wideband CDMA-2000 (Godara, 20). 4.2. Capabilities of 3G cellular phone systems 3G technologies were intended at overcoming 2G’s limited data capabilities and introduce multimedia facilities to 2G phones (Patil, Karhe and Aher, 617). 3G systems are aimed at delivering seamless network that offers to the user numerous attractive services such as Voice, multimedia, data and video services irrespective of where the user is situated within the network (Brand and Aghvami, 32). The seamless networks in 3G support global roaming while ensuring that data and multimedia applications are available at high speed of local area 2Megabits per second, and 144kbps while on the move. The International Telecommunication Union or ITU body is responsible for defining 3G technologies and the main 3G standards are direct spread or International mobile telecommunication or IMT-2000 CDMA direct spread (Wideband Code Division Multiple Access, WDCMA or Universal Mobile Telecommunication System or UMTS); IMT-2000 CDMA multi-carrier or CDMA-2000, and IMT-2000 CDMA TDD or UMTS Terrestrial Radio Access, UTRA TDD and Time Division or TD-Synchronous CDMA, TDSCDMA (Brand and Aghvami, 36; Patil, Karhe and Aher, 617). 3G systems have the capacity to provide continued mobile telecommunications coverage from anywhere on the surface of the earth. Video conferencing is one attractive service of 3G systems where long distance parties engage in face to face communications and this service has been very crucial especially for business environment (Godora, 21). 4.2.1. 3GPP or 3G partnership project for wideband CDMA standard The operation of 3GPP is founded on backward compatibility with GSM and PDC. The three main standards involved in 3GPP are WCDMA, TD-SDMA and EDGE or enhanced data for GSM evolution (Patil, Karhe and Aher, 617). WCDMA or UMTS utilizes FDD and TDD or time division duplexing and is GSM backward compatible. The forward link has up to 5GHz bandwidth while the rate of data transfer is 2Mbps. Compared to GSM, UMTS is about six times spectral efficient. The TD-SCDMA is also GSM compatible and offers channel data rate of 2.227 Mbps while the channel has a bandwidth of 1.6MHz (Brand and Aghvami, 38). TDD is the only duplexing techniques uses in TD-SCDMA. The TD-SCDMA standard offers internet services in non-real time, email, facsimile and web surfing characterized by higher downloading speed compared to the uploading speeds (Patil, Karhe and Aher, 617). EDGE is more advanced than WCDMA and TD-SCDMA and is also referred to as advanced GPRS. UMTS terrestrial radio or UTRA standard consists of several hierarchical layers where the higher layers utilize W-CDMA and users have full access to allocated bandwidth (Godara, 21). The macro layer offers 144kbps data rates while lower layers offer data rates of 384kbps and 2Mbps through FDD. 4.2.2. 3GPP2 or 3G partnership project for CDMA-2000 standard This 3G technology is compatible to 2G IS-95 and 2.5G technique. 3G-CDMA 2000 1XRTTor 1X Real Time Transfer, or radio transmission technology refers to one radio channel with 1.25MHz bandwidth and 2Mbps data rate. 5.0. Fourth generation or 4G systems 5.1. Date of implementation and capabilities. This standard was implemented in 2010 and offers higher channel capacity, fully Internet Protocol or IP-based data and multimedia of up to hundreds of megabits. 4G is a single standard that offers advanced features like High Definition or HD mobile TV and mobile ultra-broadband access to the internet (Patil, Karhe and Aher, 618). The orthogonal frequency division multiplexing or OFDM, Software Defined Radio or SDR and MIMO or multiple input multiple output technologies are used (Brand and Aghvami, 40). Unlike FDM, OFDM has the subcarriers situated orthogonal to each other as a way of interference reduction and frequency selective fading reduction to avoid affecting the signal under transmission. Since the orthogonal placement of subcarriers eliminates cross-talk in the channel, no intercarrier guard bands are needed (Patil, Karhe and Aher, 618). Patil, Karhe and Aher assert that the efficiency of the spectrum is improved in 4G given that FFT or Fast Fourier Transforms are used in the conversion of signals in the time domain to signals in the frequency domain which also reduced computational time (617). MIMO system utilizes equal number of antennas at the transmitter and receiver as a way of enhancing bit error rate or BER and the rate of data in order to sustain the capacity of the system. The Software defined radio technology makes use of a generic hardware platform to run radio functionality as a software module which makes it interoperable, flexible, re-configurable and connective (Brand and Aghvami, 46). However, this standard is complex and suffers insufficiency of Analog to digital converters, ADC. Since 4G offers high rates of data, at least 200Mbps, the users are promised speedy communication with faultless handoffs which guarantee efficient communication over wireless link. 6.0. Comparison between inherent features of each Cellular technology 1G 2G 3G 4G First implementation 1981 1991 2001 2010 Services Analog speech Digital short message and voice High capabilities of data rates up to 2Mbps IP-based multimedia, data up to hundreds of megabits Available standards AMPS, NMT, NTT and others TDMA, GSM, CDMA WCDMA and CDMA-2000 One standard Rate of data transfer N/A 14.4kbps 2Mbps More than 200Mbps Multiplexing technology FDMA TDMA and CDMA CDMA OFMA foundation network PSTN PSTN Packet switched Internet 7.0. Conclusion The paper offered a comprehensive review of the development milestones for cellular communication systems from first generation to the fourth generation. The evaluation reveals that the growth rate of mobile technologies was very swift with the 1G mobile technologies commencing the concept of cellular networks and laying a firm foundation for the succeeding cellular technologies and only provided fundamental services for speech given that it utilized analog cellular systems. The second generation or 2G cellular network comprised of cellular standards that did improve transmission security and quality of voice as well as provide a basis on which data transmission value added services were to be founded. The third generation systems that were invented in the 21st century did offer the user with a seamless network for data, voice, video and multimedia services irrespective of their location in the network whether fixed, cellular, cordless or satellite among others. Since 3G utilizes packet switched programmable networks, both voice and packet services can be integrated while global roaming is supported at high speed media and data applications. The development of 4G has led to the increased data rates higher than 200Mbps which facilitates faultless handoffs around every geographical area which then translate s to efficient communication and secure connection. Appendix 1G First Generation cellular phone systems 2G Second Generation cellular phone systems 3G Third Generation cellular phone systems 4G Fourth Generation Cellular Phone Systems 3GPP 3G global partnership projects for wideband CDMA standard 3GPP2 3G global partnership projects for wideband CDMA-2000 standard A ADC Analog Digital Converters AMPS Advanced Mobile Phone Service B BER Bit Error Rate BS Base station BSS Base Station System C CDMA Code Division Multiple Access CIA Common Air Interface CN Core Network D DCS Digital Cellular Systems DQPSK Differential Quardrature Phase Shift Keying DTC Digital Traffic Channel EDGE Enhanced Data for GSM Evolution F FCC Forward Control Channels FDMA frequency Division Multiple Access FDD Frequency Division Duplexing FFT Fast Fourier Transform G GMSK Gaussian Minimum Shift Keying GSM Global Systems for Mobile Communications H HD High definition HSCSD High Speed Circuit-Switched Data I IMT International Mobile Telecommunication IS Interim Standard ITU International Telecommunication Union K Kbps Kilobits per second M Mbps Megabits per second ME Mobile Equipment MHz MegaHertz MIMO Multiple Input Multiple Output MLS Mobile Location Services MS Mobile Station N NMT Nordic Mobile Telephone NTT Nippon Telephone Telegraph O OFDM Orthogonal Frequency Division Multiplexing P PDC Personal Digital Cellular PROM Programmable Read Only Memory R RCC Reverse Control Channels RTT Real Time Transfer S SDR Software Define Radio SIM Subscriber Identity Module T TACS Total Access Communication System TDD Time Division Duplexing TDMA Time Division Multiple Access TDSCDMA Time Division Synchronous Code Division Multiple Access U UMTS Universal Mobile Telecommunication System UTRA UMTS Terrestrial Radio Access W WAP Wireless Application Protocol WDCMA Wideband Code Division Multiple Access Works cited Brand, Alex and Aghavami, Hamid. Multilple Access protocols for mobile communications: GPRS, UMTS and Beyond. John Willey & Sons: England. 2002. Print. Godara, Lal. Handbook of Antennas in wireless communications. United States of America: Taylor & Francis. 2010. Print. Patil, C., Karhe, R. And Aher, M. Review on generations in mobile cellular technology. International Journal of emerging technology and advanced Engineering. 2(10):614-619. Read More