Smartphones support an increasing number of ways to connect to other phones, the mobile phone networks, desktop computers and the internet. We have provided a brief description of the major connectivity technologies in use below.
2G is short for second-generation wireless telephone technology. The main differentiator to previous mobile telephone systems, retroactively dubbed 1G, is that the radio signals that 1G networks use are analogue, while 2G networks are digital.
2G technologies can be divided into TDMA-based and CDMA-based standards. The main 2G standards are:
2.5G is a stepping stone between 2G and 3G cellular wireless technologies. The term 2.5G, invented for marketing purposes, is used to describe 2G-systems that have implemented a packet switched domain (such as GPRS) in addition to the circuit switched (CSD) domain. 2.5G provides some of the benefits of 3G (e.g. it is packet-switched) and can use some of the existing 2G infrastructure in GSM and CDMA networks. Some protocols, such as EDGE for GSM and CDMA2000 1x-RTT for CDMA, can qualify as "3G" services (because they have a data rate of above 144 Kbps), but are considered by most to be 2.5G services (or 2.75G which sounds even more sophisticated) because they are several times slower than "true" 3G services.
3G is short for third-generation technology for mobile phone networks. 3G provides the ability to transfer both voice data (a telephone call) and non-voice data (such as downloading information, exchanging email, and instant messaging) at much greater data speeds than the 2 and 2.5G technologies (up to 384kps for mobile devices).
Bluetooth is an industrial specification for wireless Personal Area Networks (PANs), also known as IEEE 802.15.1. Bluetooth provides a way to connect and exchange information between devices like personal digital assistants (PDAs), mobile phones, laptops, PCs, printers and digital cameras via a secure, low-cost, globally available short range radio frequency.
Listed below are the standard Bluetooth profiles usually implemented on a mobile phone (although not all handsets may include these profiles and some include more):
Other standard Bluetooth profiles include (not all of these profiles are relevant to mobile handsets):
Code Division Multiple Access is a mobile digital radio technology that transmits streams of bits and whose channels are divided using codes (PN sequences). CDMA permits many radios to share the same frequency channel. Unlike TDMA (time division multiple access), a different technique used in GSM and D-AMPS, all radios can be active all the time, because network capacity does not directly limit the number of active radios. Since larger numbers of phones can be served by smaller numbers of cell sites, CDMA-based standards have a significant economic advantage over TDMA and FDMA based standards.
CDMA2000 is a family of third-generation (3G) mobile telecommunications standards that use CDMA to send voice data, and signalling data between mobile phones and cell sites. It is the second generation of CDMA digital cellular. CDMA2000 is an incompatible competitor of the other major 3G standard, UMTS.
Circuit Switched Data is the original form of data transmission developed for the GSM mobile phone network. A circuit switching network is one that establishes a dedicated channel between nodes and terminals before the users may communicate, like a voice call.
CSD can be thought of as equivalent to a dialup modem connection, with a data transmission speed of 9.6 Kbits/sec (Computer modems on normal phone lines now generally operate at 56 Kbits/sec). CSD requires the phone to make a special connection to the network before it can transfer data (like making a voice call) which can take up to 30 seconds. Once connected, the data is sent or received via the connection and the user is billed for the time spent online.
EDGE is short for Enhanced Data rates for GSM Evolution. EDGE is a digital mobile phone technology which acts as a bolt-on enhancement to 2G and 2.5G GPRS networks. EDGE is a superset of GPRS and can function on any network with GPRS deployed on it, provided the carrier implements the necessary upgrades. EDGE can carry data at speeds of up to 236.8 Kbps and therefore meets the ITU's requirement for a 3G network.
Frequency Division Multiple Access is a technology used by mobile phone networks. In FDMA, a given RF bandwidth is divided into smaller frequency bands called subdivisions. Each subdivision has its own carrier frequency. A control mechanism is used to ensure that two or more earth stations do not transmit in the same subdivision at the same time. Essentially, the control mechanism designates a receiving station for each of the subdivisions.
General Packet Radio Service is a mobile data (packet switched) service available on the GSM mobile phone network. On a packet switching network, packets (individual blocks of data) are individually routed between nodes over data links which might be shared by many other nodes. An analogy for a packet switched network is the postal service with packets being sent and received from multiple sources and recipients.
With a GPRS connection, the phone is "always connected" and can transfer data immediately. Users are billed for the amount of data transferred rather than for the time spent connected to the GPRS network. GPRS is often described as "2.5G", with data downloaded at higher speeds than CSD at around 32-48 Kbps.
The Global System for Mobile Communications is the most popular standard for mobile phones in the world. GSM is used by over 1.8 billion people across more than 210 countries. The ubiquity of the GSM standard makes international roaming very common between mobile phone operators, enabling subscribers to use their phones in many parts of the world. GSM is considered a second generation (2G) mobile phone system and is an open standard. As the GSM standard developed (GPRS, EDGE), it retained backward compatibility with the original GSM phones.
Mobile phones connect to GSM by searching for cells in the immediate vicinity (cellular network). GSM networks operate in four different radio frequencies; 850, 900, 1800 and 1950MHz. Most GSM networks operate in the 900 MHz or 1800 MHz bands. Some countries in the Americas use the 850 MHz and 1900 MHz bands because the 900 and 1800 MHz frequency bands were already allocated.
Most new GSM phones are either tri-band (supporting 3 of the 4 GSM frequencies) or quad-band (supporting all of the frequencies). Older phones tended to be either single or dual-band only which limits the areas in which the phone can roam.
High-Speed Circuit-Switched Data is an enhancement to Circuit Switched Data (CSD) and provides increased data throughput at up to 57.6 Kbps.
Integrated Digital Enhanced Network is a mobile communications technology, developed by Motorola, which provides its users the benefits of a trunk radio and a cellular telephone. iDEN places more users in a given spectral space, compared to analogue cellular systems, by using TDMA. Up to six communication channels share a 25 kHz space. Some competing technologies place only one channel in 12.5 kHz.
The Infrared Data Association defines physical specifications communications protocol standards for the short range exchange of data over infrared light. IrDA is a very short-range example of free-space optical communication and IrDA interfaces are commonly used in palmtop computers and mobile phones. The IrDA specifications include IrPHY, IrLAP, IrLMP, IrCOMM, Tiny TP, IrOBEX, and IrLAN. IrDA has now produced another standard, Infrared Financial Messaging (IrFM) for making payments also known as "Point & Pay." For devices to communicate via IrDA, the Infrared ports on each device must have a direct line of sight to each other and be within the operating range (which varies according to the power of the infrared signal).
Personal Digital Cellular is a 2G mobile phone standard developed and used exclusively in Japan. The services include voice, call waiting, voice mail, three-way calling, call forwarding, data service (up to 9.6 Kbps CSD), and packet-switched wireless data (up to 28.8 Kbps PDC-P).
Compared to GSM, PDC's weak broadcast strength allows small, portable phones with light batteries at the expense of substandard voice quality and problems maintaining the connection, particularly in enclosed spaces like elevators.
Time Division Multiple Access is a technology used in mobile phone networks (GSM, PDC and iDEN). It allows several users to share the same frequency by dividing it into different timeslots. The users transmit in rapid succession, one after the other, each using their own timeslot. This allows multiple users to share the same transmission medium (usually the same radio carrier frequency) without transmitting simultaneously and confusing the signal.
Universal Mobile Telecommunications System (UMTS) is a third-generation (3G) mobile phone technology. It uses W-CDMA (Wideband code division multiple access) as the underlying standard, and is the European/Japanese answer to the ITU IMT-2000 requirements for 3G Cellular radio systems.
To differentiate UMTS from competing network technologies, UMTS is sometimes marketed as 3GSM, emphasizing the combination of the 3G nature of the technology and the GSM standard which it was designed to succeed. UMTS supports up to 1920 kbit/s data transfer rates, although currently users can expect performance up to 384 Kbps although Japan is preparing upgrades for transfer rates of up to 3 Mbps. However, this is still much greater than the 14.4 Kbps of a single GSM error-corrected CSD channel or multiple 14.4 Kbps channels in HSCSD and, in competition to other network technologies such as CDMA-2000, PHS or WLAN, offers access to the World Wide Web and other data services on mobile devices.
Wireless Fidelity or Wi-Fi as it is more commonly known describes the underlying technology of wireless local area networks (WLAN) based on the IEEE 802.11 specifications. A person with a Wi-Fi device, such as a computer, telephone, or personal digital assistant (PDA) can connect to the Internet when in proximity of an access point. The region covered by one or several access points is called a hotspot. Hotspots can range from a single room to large metropolitan areas, such as Philadelphia and San Francisco, where citywide hotspots have been created to allow free internet access for all. Wi-Fi also allows connectivity in peer-to-peer mode, which enables devices to connect directly with each other. This connectivity mode is useful in consumer electronics and gaming applications.
IEEE 802.11, the Wi-Fi standard, denotes a set of WLAN standards developed by working group 11 of the IEEE LAN/MAN Standards Committee. The 802.11 family currently includes six over-the-air modulation techniques that all use the same protocol. The most popular (and prolific) techniques are those defined by the b, a, and g amendments to the original standard.
The 802.11b and 802.11g standards use the 2.4 gigahertz (GHz) band. Because of this choice of frequency band, 802.11b and 802.11g equipment can incur interference from microwave ovens, cordless telephones, Bluetooth devices, and other appliances using this same band. The 802.11a standard uses the 5 GHz band, and is therefore not affected by products operating on the 2.4 GHz band but generally operates over much shorter distances.
| Standard | Release date | Op. Freq | Data Rate (Typical) | Data Rate (Max) | Range (Indoors) |
|---|---|---|---|---|---|
| 802.11b | 1999 | 2.4GHz | 6.5 Mbps | 11 Mbps | 30 metres |
| 802.11a | 1999 | 5GHz | 25 Mbps | 54 Mbps | 10 metres |
| 802.11g | 2003 | 2.4GHz | 25 Mbps | 54 Mbps | 30 metres |
Note: 802.11a is incompatible with both 802.11b and 802.11g and vice versa as they operate on different frequencies whilst 802.11b and 802.11g are compatible with each other. Therefore in terms of implementation an 802.11a adapter can only operate on an 802.11a network whilst an 802.11b or 802.11g card can operate on either an 802.11b or an 802.11g network (although not faster than the network or card, whichever is slowest - i.e. An 802.11g card on an 802.11b network can only operate at the 802.11b maximum of 11 Mbps or slower).