Work and Life in the Mobile Society/Technology/Standards

When Motorola and Bell operated the first commercial mobile telephone service MTS in the US in 1946, nobody had expected that the mobile technology would boom so rapidly during the past 60 years. Nowadays, people would rather carry one simple fancy device during travel, such as iPhone, for talking, web surfing, business meeting, and mobile working than carrying a laptop, a PDA, a phone, and a pager.

What happened in the mobile society? The key technology improvement is the communication standard. Mobile technology has experienced five generations since it was first introduced. The overall trend of the technical standard is to make it faster, have more bandwidth, and to be more unified.

Historical Development
Pre cellular system is the predecessor to the first generation of cellular telephones, hence it is sometimes referred to as 0G. Technologies used in pre cellular systems included the Push to Talk (PTT or manual), Mobile Telephone System (MTS), Improved Mobile Telephone Service (IMTS), and Advanced Mobile Telephone System (AMTS) systems.

First generation system was first introduced in US during 1980’s. It was implemented through analog signal and was considered as luxury goods for seldom people at that time. The standards of 1G includes NMT (Nordic Mobile Telephone), AMPS (Advanced Mobile Phone System), TACS (Total Access Communications System), C-450, Radiocom 2000, and RTMI. Theses standards were launched and used by different countries in Europe and North American. In Asia, the most advanced standards were launched in Japan, such as TZ-801, TZ-802, TZ-803, and JTACS standard.

Second generation standard was first commercially launched on GSM by Radiolinja in Finland in 1991. It was the first digitally encrypted standard, and was significantly more efficient on the spectrum allowing for far greater mobile phone penetration levels. Furthermore, 2G introduced data services for mobile, starting with SMS text messages. 2G technologies can be divided into TDMA-based and CDMA-based standards depending on the type of multiplexing used. The main TDMA-based 2G standards include GSM, mainly in Europe; PDC, exclusively in Japan; and iDEN, proprietary network used in North American. The CDMA-based standard IS-95, used in the Americas and parts of Asia.

Second and half generation mobile system is a standard between 2G and 3G mobile technology. It improves from circuit switched domain to packet switched domain. It is not necessarily faster then 2G because bundling of timeslots is used for circuit switched data services (HSCSD) as well. The 2G standard includes GPRS, HSCSD, and WiDEN.

2.75 generation mobile technology, usually known as Enhanced Data rates for GSM Evolution (EDGE), Enhanced GPRS (EGPRS), or IMT Single Carrier (IMT-SC), is an extension of GSM standard. It allows improved data transmission rates by switching to more sophisticated methods of coding, within existing GSM timeslots. It is very close to the 3G technology.

Third generation technology has been discussed for many years. It is first introduced by ITU (International Telecommunication Union) in 1985 and was first launched in 2001. 3G standard enable wider range of more advanced services with greater network capacity through improved spectral efficiency. Services include wide-area wireless voice telephony, audio and video signals all in a mobile environment. The data transmission rate in 3G is up to 14.4Mbit/s on the downlink and 5.8Mbit/s on the uplink. The most accepted standards of 3G are W-CDMA, CDMA2000, and TD-SCDMA.

Three and half generation refers to the mobile standard of High Speed Downlink Packet Access (HSDPA). It provides variable spreading factor and fast power control. Instead, it delivers the improved downlink performance using adaptive modulation and coding (AMC), fast packet scheduling at the base station, and fast retransmissions from the base station, known as hybrid automatic repeat-request (HARQ).

3.75 generation extended the mobile technology from 3.5G by improving the High Speed Uplink Packet Access (HSUPA). It allows up-link speeds up to 5.76Mbps. HSUPA uses a packet scheduler, but operates on a request-grant principle where the users request a permission to send data and the scheduler decides when and how many users will be allowed to do so. However, HSUPA also allows a self-initiated transmission mode from the users, denoted non-scheduled mode. The non-scheduled mode can, for example, be used for VoIP services which can provides the very short delay time and constant bandwidth requirement.

The fourth generation mobile technology is supposed to provide such a comprehensive solution with higher data rates than any of the previous generations. Although there is no formal definition for 4G yet, the objectives of 4G is quite clear. It includes a fully IP-based integrated system, so that it can support up to 100Mbps and 1Gbps speeds as ADLS network, for both indoors and outdoors, stable and highly mobile environment. Many companies have launched their pre-4G standards such as WiMAX, Flash-OFDM, 3GPP Long Term Evolution, UMB, and IEEE 802.20.