Brief History Of Mobile Communication

1. Brief History of Mobile Communication

Communication represents a two-way process in which people not only exchange (encode-decode) information, share ideas, news or feelings, but also they reach a common understanding of content. Due to the necessity of connecting people or places, ways to improve long distance communications was developed using wired and later wireless communications systems, today known as mobile communications. Starting from the idea that it would serve an academic and military purpose and afterwards a civil usage, mobile communications were developed ceaselessly going through several stages until now:

First generation (1G) mobile communication system;

Second generation (2G) mobile communication system;

Third generation (3G) mobile communication system;

Fourth generation (4G) mobile communication system;

1.1 First generation of mobile communications system (1G) was deployed in the Nordic countries in 1981 being entitled Nordic Mobile Telephone (NMT) and was followed by similar systems in the USA in 1983, called  AMPS (Advanced Mobile Phone System) and then, up to mid-1980s it was launched in the UK, Canada, Mexico. It was based on voice transmission using frequencies around 900 MHz and analogue modulation. The initial idea was to provide coverage to large geographical regions and network planning was including a limited number of sites. The network capacity and services have been designed to a very small percentage of the population. A single site was covering a big enough area and often there was no alternative handover when users enter a zone where the signal loss was very high. There could not be provided roaming between the networks of other countries and security was weak because of the interceptions via air interface. Due to the need of improved transmission quality, coverage and system capacity the next generation cellular system was developed. [1]

1.2 Second generation of mobile communications system (2G) also called GSM (Global System for Mobile Communications) is far superior to the first generation. It was launched in Finland in 1991 using digital radio signals. The network quality and capacity was enhanced by release new services such as protection against fraud, data encryption, low rate circuit switched data services, interconnection with ISDN and PSTN.

The first GSM system used the frequency spectrum of 25MHz in the band of 900MHz. Nowadays GSM systems work in the 900MHz and 1.8 GHz bands all over the world, apart from Americas where it functions in the 1.9 GHz band.

Several standards were introduced: FDMA, TDMA, and CDMA. FDMA (Frequency Division Multiple Access) standard splits the available 25MHz band into 124 carrier frequencies of 200 kHz each and then using a TDMA (Time Division Multiple Access) scheme is divided each frequency into 8 timeslots allowing 8 simultaneous calls on the same frequency. CDMA (Code Division Multiple Access) technology uses spread spectrum to break up speech into small, digital sections and encodes them to identify each call. While CDMA splits the call by codes, the TDMA breaks it down by time, in both cases resulting a higher network capacity and absence of interferences. [1]

The GSM networks aforesaid are mostly based on circuit switched technology, providing wireless internet access and reaching data rates of up to 9.6 kbps, but are not suitable for web browsing at high speed. For the purpose of improving the throughput the GSM standard has been extended. [1]

In order the meet the demand for wireless internet access, 2.5G system entitled GPRS (General Packet Radio Service) was introduced and it allows the MS to reach a maximum data speed of 171.2 kbps(?sau 114) theoretically, but with a throughput closer to 40 Kbit/s in practice.

GPRS assures a way to aggregate radio channels for higher data bandwidth and the auxiliary servers off-load packet traffic from current GSM circuits, thus providing an end-to-end mobile data services based on packet switching technology. GPRS services introduce 2 new network components: the Gateway GPRS Support Node (GGSN) and the Serving GPRS Support Node (SGSN).

GGSN – behaves like a gateway/logical interface between the external PDN (Packet Data Networks) such as Internet and other PLMNs. It routes the incoming data packets to the SGSN. GGSN could interface straightly with the HLR (Home Location Register) using the Gc interface. GGSN examines the PDN address of the MS and turn it into adequate IMSI.

SGSN – searches for the location of mobile phones and it is dealing with routing packet traffic to the MS in its service area and from the MS to the Internet. It checks the access to MSs, belonging to a group of BSCs. It also performs the GPRS channel assignment, logical link management, encryption, authentication and charging. [3]

The SGSN via Gn interface is connected to GGSNs belonging to its own PLMNs (Public Land Mobile Network) and to GGSNs via Gp belonging to other PLMNs. Gn and Gp interfaces are alike, but the Gp supports additional security functions that are necessary for inter-PLMN communications.

The following standard is 2.75G known as EDGE (Enhanced Data rates for GSM Evolution or Enhanced GPRS). EDGE is generally considered a 3G technology, establishing new physical level methods, including a new modulation technique (8 PSK) and various ways of encoding data to guard against errors. High-level protocols, such as those used by GGSN and SGSN, remain the same. This method improves the data transmission rate during GSM radio connection, the speed reaches a peak of 384 kbps.

By introducing sophisticated methods for encoding and transmitting data, EDGE offers a much higher transfer rate thus leading to a 3-fold increase in capacity and performance compared to GSM and GPRS. Being an advanced GPRS-to-UMTS technique, EDGE provides PC multimedia communication services before 3G technology to be launched and it also empowers the network provider to make use of the existing radio network equipment to the maximum. [2] [4]

The EDGE standard is the development of GSM towards 3G.

1.3 Third generation of mobile communication system (3G) also entitled UMTS (Universal

Mobile Telecommunications System) represents a significant evolution in services and transfer speed compared to 2G and is a real path for the products development and multimedia capabilities.

The UMTS system, first offered in 2001 was standardized by 3GPP, which globally applies 3G mobile phone system specification based on evolved GSM specifications within the scope of the International Mobile Telecommunications-2000. 3GPP standardization encompasses Radio, Core Network and Service architecture:

The core (switching) network is responsible for performing switching and transmission functions.

The control (service) network supports roaming due to the existence of mobility management features.

The radio access networks provide channel access to mobile users, realizing radio resource management and signaling. [5]

With the blooming of mobile internet, 3G technology opens the door to a spick and span mobile communication world. UMTS is using W-CDMA technology and the available applications comprise wide-area wireless voice phone, mobile Internet access, video calls and mobile TV, all in a mobile environment.

The data rate was improved reaching speeds of 2Mbps or even up to 8Mpbs in special cases. Being a digital signal processing systems that works in the 2 GHz band, it has high-quality multimedia services and operates in different environments. The 3G technology has been standardized to ensure worldwide compatibility and a compatibility of 3rd generation mobile services with 2nd generation networks. UMTS includes both terrestrial and global satellite components.

Worldwide 3G was adopted relatively slow. In some cases, 3G networks do not use the same radio frequencies as 2G, consequently mobile operators have to build entirely new networks and buy licenses for new frequencies which permit high transmission rates.

The terminology of "mobile broadband" was also introduced by 3G technology due to the fact that its speed and capacity became a viable alternative for web browsing and connection to 3G networks using USB modems was increasingly common.

The 3G standard reached popularity due to the massive expansion of the communications market and smartphones, combining the features of a PDA with a classic mobile phone, leading to a large demand for mobile Internet connectivity. The 3G technology is divided in 2 types of services: voice (circuit-switch) and data (packed-switch).

The following standard, 3.5G known as HSDPA (High-Speed Downlink Packet Access), is a communication protocol in HSPA (High-Speed Packet Access) class that is part of the 3G mobile and allows networks based on UMTS have higher data rates and greater capacity. HSDPA+ deployment permits download speeds of up to 42 Mbps using a dual carrier access and allows simultaneous transfer of voice and high-speed digital data.

1.4 Fourth generation of mobile communication system (4G) entitle LTE (Long Term

Evolution) represents the ultimate telecommunications technology available nowadays.

LTE is a standard for mobile wireless communication with high speed data transfer. It is based on GSM / EDGE and UMTS / HSPA network technologies, increasing capacity and speed using a different radio interface and core network improvements.

LTE came with a fast increase in the use of data carried by cellular services which has been called the "data explosion". With the growing demands for higher data transmission speeds and lower latency, the cellular technology required additional improvement.

Having the architecture based on Internet Protocol (IP), LTE supports Web browsing, VoIP, high definition mobile TV, cloud computing, 3D television and other IP-based services well. LTE provides data rates of 100 Mbps for download and 50Mbps for upload. It also has to sustain minimum 200 dynamic users in each 5MHz cell, for example 200 acting calls.

LTE is using the following technologies:

OFDM technology – incorporated into LTE because it permits generous transmission of high data bandwidths whilst still assuring in a great extent the adaptability to reflections and interferences.

MIMO (Multiple Input Multiple Output) takes as an advantage the many signals arising from the multiple reflections which are coming across. Using MIMO, these additional signal paths lead to the increasing of the throughput.

Although LTE is still under development and it is not already deployed all over the world, the 5G technology is undergoing standardization in the meantime.

Bibliography

[1] Evolution of Mobile Communications: from 1G to 4G,

https://eden.dei.uc.pt/~vasco/Papers_files/Mobile_evolution_v1.5.1.pdf, accessed on 05.01.2016.

[2] John Wiley & Sons Ltd, Gsm, Cdmaone And 3G Systems, 2001, in chapter 6, Evolution of GSM and CdmaOne to3G Systems, page 413.

[3]C.S.R. Prabhu, Mobile Computing: A Book of Readings, Universities Press (India) Private Limited 2002, page 13.

[4] Generations of network 1G, 2G, 3G, 4G, 5G,

http://www.slideshare.net/noorec786/generations-of-network-1-g-2g-3g-4g-5g, accessed on 30.03.2016 (chapter 4, page 16)

[5] Chai K Toh, Ad Hoc Mobile Wireless Networks: Protocols and Systems, 2002

List of Abbreviations

MS – Mobile Station

GSM – Global System for Mobile Communications

ISDN – Integrated Services Digital Network

PSTN – Public switched telephone network

GPRS – General Packet Radio Service

GGSN – Gateway GPRS Support Node

SGSN – Serving GPRS Support Node

PLMN – Public Land Mobile Network

UMTS – Universal Mobile Telecommunications System

3GPP – 3rd Generation Partnership Project

W-CDMA – Wide Code Division Multiple Access

LTE – Long Term Evolution