Understanding mobile technology
Posted 24 March 2005 - 08:13 PM
Types of networks and where they are used
GSM 900 (transmitting on the 900 MHz frequency band) is Europe's main digital network. It's also used in the Asia-Pacific region.
GSM 1800 (transmitting on the 1800 MHz frequency band) is also used in Europe and Asia, but has not been as widely adopted as GSM 900.
GSM 1900 (transmitting on the 1900 MHz frequency band) is the GSM system used mainly in the Americas and Canada.
TDMA is a digital standard used primarily in the US, but also in Latin America, New Zealand, parts of Russia and the Asia-Pacific region.
CDMA is the most common and most recent digital cellular technology in North America.
AMPS is used mainly in the US. It's also used in Latin America, Australia, New Zealand, parts of Russia and the Asia-Pacific region.
ETACS is used in Europe and the Asia-Pacific region.
NMT is used in Scandinavia and some European countries, as well as parts of Russia, the Middle East and Asia.
Definitions - GSM, TDMA, CDMA, Cellular, PDC, GPRS, WCDMA, PCS, 3G, ITU
Short for 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. By the end of 1997, the GSM service was available in more than 100 countries. It has become the de facto standard in Europe and Asia.
Considered the most advanced digital cellular technology, GSM networks are leaders in many typically "digital" services including Short Message Service (SMS), Over the air (OTA) configuration and GSM positioning. Thanks to its technology and presence both in the Americas and the rest of the world, GSM is well positioned for global roaming. Many new GSM phones are called "global phones", because they can be used in virtually any country. The SIM card ("Subscriber Identification Module") is also a unique and essential component of GSM phones.
Technically, GSM was based on the TDMA protocol.
Short for Time Division Multiple Access, TDMA is a technology for delivering digital wireless service using time-division multiplexing (TDM). It works by dividing a radio frequency into time slots, 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.
One of the oldest digital cellular technologies, TDMA is used mostly in North America. It is considered the least advanced digital technology, partly because of its lack of flexibility compared with other digital cellular technologies.
Short for Code-Division Multiple Access, this is a digital cellular technology that uses spread-spectrum techniques. Unlike competing systems that use TDMA, such as GSM, CDMA does not assign a specific frequency to each user. Instead, every channel uses the full available spectrum.
Individual conversations are encoded with a pseudo-random digital sequence. What differentiates CDMA from other phone technologies is that it carries many conversations by sending all communications in groups of bits mixed together, and tagging each group belonging to a specific communication with a different code. Each communication can therefore be reassembled in the correct order at the other end, using the unique codes attached to particular groups of bits.
Refers to communications systems, especially the Advance Mobile Phone Service (AMPS), that divide a geographic region into sections called cells. The purpose of this division is to make the most efficient use of a limited number of transmission frequencies. Each connection, or conversation, requires its own dedicated frequency, and the total number of available frequencies is about 1,000.
To support more than 1,000 simultaneous conversations, cellular systems allocate a set number of frequencies to each cell. Two cells can use the same frequency for different conversations, provided the cells are not adjacent.
Personal Digital Cellular (PDC) is one of the world's three main digital wireless standards, ranking alongside GSM and TDMA. Although all users are currently in Japan, operators in other regions of the world are actively considering PDC. Although PDC is currently only used in Japan, it is the world's second-largest digital standard, with over 48 million subscribers by July 2000. As with GSM, PDC is based on TDMA technology.
GPRS (General Packet Radio Service) is a step between GSM and 3G cellular networks. GPRS offers faster data transmission (9.6Kbits to 115Kbits) via a GSM network. This new technology enables users to make telephone calls and transmit data at the same time. (For example, if you have a GPRS mobile phone, you will be able to make calls and receive email messages simultaneously.) The main benefits of GPRS are that it reserves radio resources only when there is data to send, and reduces reliance on traditional circuit-switched network elements.
Short for wideband CDMA, this is a high-speed 3G mobile wireless technology that can offer higher data speeds than CDMA. WCDMA can reach speeds of up to 2 Mbps for voice, video, data and image transmission. WCDMA was adopted as a standard by the ITU under the name "IMT-2000 direct spread."
Short for Personal Communications Service, PCS is the U.S. Federal Communications Commission (FCC) term used to describe a set of digital cellular technologies being deployed in the U.S. PCS works over CDMA (also called IS-95), GSM and North American TDMA (also called IS-136) air interfaces. Three of the most important distinguishing features of PCS systems are:
* They are completely digital.
* They operate in the 1900 MHz frequency range.
* They can be used internationally. PCS is a second-generation mobile communications technology.
3G is an ITU specification for the third generation (analogue cellular was the first generation, digital PCS the second) of mobile communications technology. 3G promises increased bandwidth of up to 384 Kbps when a device is stationary or moving at pedestrian speed, 128 Kbps in a car and 2 Mbps in fixed applications. 3G will work over wireless air interfaces such as GSM, TDMA and CDMA. The new EDGE air interface has been developed specifically to meet the bandwidth needs of 3G.
Short for International Telecommunication Union. The ITU is an intergovernmental organisation through which public and private organisations 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 standardisation functions were formerly performed by a group within the ITU called the CCITT, but since a 1992 reorganisation the CCITT no longer exists as a separate body.
Enhanced data for global evolution (EDGE) is a high-speed mobile data standard, intended to enable second-generation global system for mobile communication (GSM) and time division multiple access (TDMA) networks to transmit data at up to 384 kilobits per second (Kbps). As it was initially developed just for GSM systems, it has also been called GSM384. Ericsson intended the technology for those network operators who failed to win spectrum auctions for third-generation networks to allow high-speed data transmission.
EDGE provides speed enhancements by changing the type of modulation used and making a better use of the carrier currently used, for example the 200kHz carrier in GSM systems. EDGE also provides an evolutionary path to third-generation IMT-2000-compliant systems, such as universal mobile telephone systems (UMTS), by implementing some of the changes expected in the later implementation in third-generation systems.
Short for High-Speed Downlink Packet Access
HSDPA's incremental UMTS network upgrade aims to increase user peak data rates and quality-of-service and improve spectral efficiency - much like EDGE and 1XRTT have done for 2G. Although UMTS enables streaming video, broadband Internet access and video conferencing, HSDPA offers peak downlink data rates of up to 14 Mbps - dramatically more than the 384 kbps that is typical of today's UMTS and the highest data rate of any available mobile WAN technology.
HSPDA works by moving important processing functions closer to the air interface. Although current UMTS networks perform network scheduling and retransmission in the radio network controller, HSDPA moves these functions to the base station (called Node B in UMTS systems), allowing scheduling priority to take account of channel quality and terminal capabilities. Retransmission also benefits from hybrid automatic retransmission request in which retransmissions are combined with prior signal transmissions to improve overall reception. HSDPA adds a channel-sharing mechanism that allows several users to share the high-speed air interface channel and other technological advances such as adaptive modulation and coding, quadrature amplitude modulation and channel quality feedback. These enhancements allow HSDPA to roughly double the total throughput capacity of a network.
Posted 24 March 2005 - 10:01 PM
And, in the beginning GSM was short for "Groupe Speciale Mobile" a French SIG, who had the project to develop a widely available mobile digital network
Edited by Lynott, 16 August 2009 - 11:18 PM.
My (Sony)Ericsson collection
Something for my collection? You know where to get some special (Sony)Ericssons? Let me know!
Posted 24 March 2005 - 10:07 PM
Posted 05 April 2005 - 11:21 AM
UMTS offers teleservices (like speech or SMS) and bearer services, which provide the capability for information transfer between access points. It is possible to negotiate and renegotiate the characteristics of a bearer service at session or connection establishment and during ongoing session or connection. Both connection oriented and connectionless services are offered for Point-to-Point and Point-to-Multipoint communication.
Bearer services have different QoS parameters for maximum transfer delay, delay variation and bit error rate. Offered data rate targets are:
# 144 kbits/s satellite and rural outdoor
# 384 kbits/s urban outdoor
# 2048 kbits/s indoor and low range outdoor
UMTS network services have different QoS classes for four types of traffic:
# Conversational class (voice, video telephony, video gaming)
# Streaming class (multimedia, video on demand, webcast)
# Interactive class (web browsing, network gaming, database access)
# Background class (email, SMS, downloading)
QoS = Quality of Service
I have added some more info to the original thread also
Posted 12 February 2007 - 01:55 AM
btw, there should be a GSM 850, mainly used in Canada
i live in canada, if u take a GSM 900/1800/1900 phone to canada, u WILL receive strong signal outside, but once u go in a buliding , or something else, no signal.
Posted 15 February 2007 - 09:35 PM
As for CSD, and HSCSD, they stand for Circuit Switched Data and High Speed Circuit Switched Data, respectively. Intended to be used as a wireless form of dial-up internet access, CSD runs at 9.6kbps, with HSCSD allocating up to 4 GSM channels to allow 28.8kbps. Most operators only support CSD as it puts less of a burden on their networks. Also, they typically use airtime in place of data usage as their form of billing.
As for this post, it is my first here on these forums, and was done via an EDGE connection through a W810i. I like this place
Posted 27 June 2007 - 02:19 PM
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