Time division multiple access (TDMA) is a channel access method for shared medium (usually radio) networks. It allows several users to share the same frequency channel by dividing the signal into different timeslots. The users transmit in rapid succession, one after the other, each using his own timeslot. This allows multiple stations to share the same transmission medium (e.g. radio frequency channel) while using only the part of its bandwidth they require. TDMA is used in the digital 2G cellular systems such as Global System for Mobile Communications (GSM), IS-136, Personal Digital Cellular (PDC) and iDEN, and in the Digital Enhanced Cordless Telecommunications (DECT) standard for portable phones. It is also used extensively in satellite systems, and combat-net radio systems. For usage of Dynamic TDMA packet mode communication, see below. In communications, a channel access method is used to share a communications channel or physical communications medium between multiple users. ... This article or section does not cite its references or sources. ... 2G (or 2-G) is short for second-generation wireless telephone technology. ... This article or section is not written in the formal tone expected of an encyclopedia article. ... The Global System for Mobile Communications, GSM (original acronym: Groupe Spécial Mobile) is the most popular standard for mobile phones in the world. ... IS-54 and IS-136 are second-generation (2G) mobile phone systems, known as Digital AMPS (D-AMPS). ... Personal Digital Cellular (PDC) is a 2G mobile phone standard developed and used exclusively in Japan. ... The title of this article is incorrect because of technical limitations. ... DECT or Digital Enhanced (formerly European) Cordless Telecommunications is an ETSI standard for digital portable phones, commonly used for domestic or corporate purposes. ... A portable phone or cordless phone is a wireless telephone which is associated with a fixed telephone landline (POTS) and can only be operated close to (typically less than 100 metres of) its base station, such as in and around the house. ... MILSTAR:A communication satellite A satellite is any object that orbits another object (which is known as its primary). ... In telecommunication, a combat-net radio (CNR) is a radio operating in a network that (a) provides a half-duplex circuit and (b) uses either a single radio frequency or a discrete set of radio frequencies when in a frequency hopping mode. ...

TDMA frame structure showing a data stream divided into frames and those frames divided into timeslots.

TDMA is a type of Time-division multiplexing, with the special point that instead of having one transmitter connected to one receiver, there are multiple transmitters. In the case of the uplink from a mobile phone to a base station this becomes particularly difficult because the mobile phone can move around and vary the timing advance required to make its transmission match the gap in transmission from its peers. This is a diagram of TDMA framing and timeslot structure; The diagram was drawn by me and I hereby donate the copy on Wikipedia to the Wikipedia project. ... This is a diagram of TDMA framing and timeslot structure; The diagram was drawn by me and I hereby donate the copy on Wikipedia to the Wikipedia project. ... Time-division multiplexing (TDM) is a type of digital or (rarely) analog multiplexing in which two or more signals or bit streams are transferred apparently simultaneously as sub-channels in one communication channel, but physically are taking turns on the channel. ... Antenna tower of Crystal Palace transmitter, London A transmitter (sometimes abbreviated XMTR) is an electronic device which with the aid of an antenna propagates an electromagnetic signal such as radio, television, or other telecommunications. ... In radio terminology, a receiver is an electronic circuit that receives a radio signal from an antenna and decodes the signal for use as sound, pictures, navigational-position information, etc. ... This article deals with Uplink in the telecommunications terminology. ... Two GSM mobile phone base stations disguised as trees in Dublin, Ireland. ...

TDMA features

• Shares single carrier frequency with multiple users
• Non-continuous transmission makes handoff simpler
• Slots can be assigned on demand in dynamic TDMA
• Less stringent power control than CDMA due to reduced intra cell interference
• Higher synchronization overhead than CDMA
• Advanced equalization is necessary for high data rates
• Cell breathing (borrowing resources from adjacent cells) is more complicated than in CDMA
• Frequency/slot allocation complexity
• Pulsating power envelop: Interference with other devices

General Information Generically (as a multiplexing scheme), code division multiple access (CDMA) is any use of any form of spread spectrum by multiple transmitters to send to the same receiver on the same frequency channel at the same time without harmful interference. ...

TDMA in 2G cellular systems

In the GSM system, the synchronization of the mobile phones is achieved by sending timing advance commands from the base station which instructs the mobile phone to transmit earlier and by how much. This compensates for propagation delay as the speed of radio waves is the same as light (finite). The mobile phone is not allowed to transmit for its entire timeslot, but there is a guard interval at the end of each timeslot. As the transmission moves into the guard period, the mobile network adjusts the timing advance to synchronize the transmission. 0G refers to pre-cellular mobile telephony technology. ... Push-to-Talk (PTT), also known as Press-to-Transmit, is a method of conversing on half-duplex communication lines, including two-way radio, using a momentary button to switch from voice reception mode to transmit mode. ... The Mobile Telephone System (MTS) was one of the earliest mobile telephone standards. ... The Improved Mobile Telephone Service (IMTS) is a pre-cellular VHF/UHF radio system that links to the PSTN. IMTS was the radiotelephone equivalent of land dial phone service. ... The Advanced Mobile Telephone System was a 0G method of radio communication, mainly used in Japanese portable radio systems. ... OLT (Norwegian for Offentlig Landmobil Telefoni, Public Land Mobile Telephony), was the first land mobile telephone network in Norway. ... MTD (Swedish abbreviation for Mobilelefonisystem D, or Mobile telephony system D) was a manual mobile phone system for the 450 MHz frequency band. ... Autotel (also called PALM, or Public Automated Land Mobile) is a radiotelephone service which was the missing link between earlier MTS/IMTS and later cellular telephone services. ... ARP (Autoradiopuhelin, Car Radio Phone in English) was the first commercially operated public mobile phone network in Finland. ... 1G (or 1-G) is short for first-generation wireless telephone technology, cellphones. ... For other meanings of the abbreviation, see: NMT. NMT (Nordisk MobilTelefoni or Nordiska MobilTelefoni-gruppen, Nordic Mobile Telephone in English) is a mobile phone system that was specified by the Nordic telecommunications administrations (PTTs) starting in 1970, and opened for service in 1981 as a response to the increasing congestion... Advanced Mobile Phone System (AMPS) is the analog mobile phone system standard developed by Bell Labs, and officially introduced in the Americas in 1984. ... hicap is a mobile techonology which has a consumer interface with a wide variety of industry references. ... Cellular Digital Packet Data (CDPD) uses unused bandwidth normally used by AMPS mobile phones between 800 and 900 MHz to transfer data. ... Cingular Interactive Truck at Ground Zero on 9/11/2001 Mobitex Network Design Mobitex is an OSI based open standard, national public access wireless data network first introduced in 1991 by carriers RAM Mobile Data and in Canada 1990 by Rogers Cantel. ... DataTac is a wireless data network technology originally developed by Motorola and deployed in the United States as the ARDIS network. ... 2G (or 2-G) is short for second-generation wireless telephone technology. ... The Global System for Mobile Communications, GSM (original acronym: Groupe Spécial Mobile) is the most popular standard for mobile phones in the world. ... Iden is also a village in East Sussex, England iDEN Base Radio at a Cell Site Integrated Digital Enhanced Network (iDEN) is a mobile telecommunications technology, developed by Motorola, which provides its users the benefits of a trunked radio and a cellular telephone. ... IS-54 and IS-136 are second-generation (2G) mobile phone systems, known as Digital AMPS (D-AMPS). ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Personal Digital Cellular (PDC) is a 2G mobile phone standard developed and used exclusively in Japan. ... Circuit Switched Data, often known as CSD, is the original form of data transmission developed for the GSM mobile phone system. ... The Personal Handy-phone System (PHS), also marketed as the Personal Access System (PAS), is a mobile network system operating in the 1880-1930 MHz frequency band. ... [[General Packet Radio Services (GPRS)]] is a mobile data service avaiBold textlable to users of GSM and IS-136 mobile phones. ... High-Speed Circuit-Switched Data (HSCSD), is a development of Circuit Switched Data, the original data transmission mechanism of the GSM mobile phone system. ... Wideband Integrated Dispatch Enhanced Network, or WiDEN, is a software upgrade developed by Motorola for its iDEN enhanced specialized mobile radio (or ESMR) wireless telephony protocol. ... CDMA2000 is a family of third-generation (3G) mobile telecommunications standards that use CDMA, a multiple access scheme for digital radio, to send voice, data, and signalling data (such as a dialed telephone number) between mobile phones and cell sites. ... Enhanced Data rates for GSM Evolution (EDGE) or Enhanced GPRS (EGPRS), is a digital mobile phone technology that allows for increased data transmission rate and improved data transmission reliability. ... 3G (or 3-G) is short for third-generation technology. ... W-CDMA (Wideband Code Division Multiple Access) is a type of 3G cellular network. ... Universal Mobile Telecommunications System (UMTS) is one of the third-generation (3G) mobile phone technologies. ... FOMA, officially short for Freedom of Mobile Multimedia Access, is the brand name for the 3G services being offered by Japanese mobile phone operator NTT DoCoMo. ... UMTS-TDD is a mobile data network standard built upon the UMTS 3G cellular mobile phone standard, using a TD-CDMA air interface and Time Division Duplexing to duplex spectrum between the up-link and down-link. ... 1x Evolution-Data Optimized, abbreviated as EV-DO or 1xEV-DO and often EVDO, is a wireless radio broadband data standard adopted by many CDMA mobile phone service providers in United States, South Korea, Japan, the Czech Republic, Russia, Latvia, Romania, Portugal, Brazil, Israel, Australia, Canada, New Zealand, Venezuela, Angola... TD-SCDMA (Time Division-Synchronous Code Division Multiple Access) is a 3G mobile telecommunications standard, being pursued in the Peoples Republic of China by the Chinese Academy of Telecommunications Technology (CATT), Datang and Siemens AG, in an attempt to develop home-grown technology and not be dependent on Western... The Generic Access Network (GAN), was formerly known as Unlicensed Mobile Access (UMA) until it was adopted by the 3GPP in April 2005. ... High-Speed Downlink Packet Access (HSDPA) (Sometimes known as High-Speed Downlink Protocol Access) is a 3G mobile telephony protocol in the HSPA family, which provides a smooth evolutionary path for UMTS-based networks allowing for higher data transfer speeds. ... High-Speed Uplink Packet Access (HSUPA) is a data access protocol for mobile phone networks with extremely high upload speeds up to 5. ... High Speed OFDM Packet Access (HSOPA) is part of 3gpps Long Term Evolution (LTE) upgrade path for 3G systems. ... 4G (or 4-G) is short for fourth-generation. ... Ultra Mobile Broadband is the brand name to describe the advanced technologies and services that will be supported by the CDMA2000 1xEV-DO Revision C (Rev. ... Cellular frequencies - the general term which unites radio frequencies utilized by cellular networks to provide service to their subscribers. ... Personal Communications Service or PCS is the name for the 1900-MHz radio band used for digital mobile phone services in Canada and the United States. ... The purpose of the guard interval is to introduce immunity to echoes and reflections while using COFDM coding. ...

Initial synchronization of a phone requires even more care. Before a mobile transmits there is no way to actually know the offset required. For this reason, an entire timeslot has to be dedicated to mobiles attempting to contact the network (known as the RACH in GSM). The mobile attempts to broadcast at the beginning of the timeslot, as received from the network. If the mobile is located next to the base station, there will be no time delay and this will succeed. If, however, the mobile phone is at just less than 35km from the base station, the time delay will mean the mobile's broadcast arrives at the very end of the timeslot. In that case, the mobile will be instructed to broadcast its messages starting nearly a whole timeslot earlier than would be expected otherwise. Finally, if the mobile is beyond the 35 km cell range in GSM, then the RACH will arrive in a neighboring timeslot and be ignored. It is this feature, rather than limitations of power which limits the range of a GSM cell to 35 kilometers when no special extension techniques are used. By changing the synchronization between the uplink and downlink at the base station, however, this limitation can be overcome. Random Access Channel (RACH) is used in mobile phones or other wireless device on a TDMA-based network when it needs to get the attention of a base station in order to initially synchronize its transmission with the base station. ...

In radio systems, TDMA is almost always used alongside Frequency-division multiple access (FDMA) and Frequency division duplex (FDD); the combination is referred to as FDMA/TDMA/FDD. This is the case in both GSM and IS-136 for example. The exceptions to this rule include WCDMA-TDD which combines FDMA/CDMA/TDMA and TDD instead. This article is in need of attention from an expert on the subject. ... Duplex is the having of two principal elements or parts. ... TDD can stand for several things: telecommunications device for the deaf time division duplex test driven development The airport code for Trinidad, Bolivia This page concerning a three letter acronym is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...

A major advantage of TDMA is that the radio part of the mobile only needs to listen and broadcast for its own timeslot. For the rest of the time, the mobile can carry out measurements on the network, detecting surrounding transmitters on different frequencies. This allows safe inter frequency handovers, something which is difficult in CDMA systems, not supported at all in IS-95 and supported through complex system additions in Universal Mobile Telecommunications System (UMTS). This in turn allows for co-existence of microcell layers with macrocell layers. But, CDMA supports "soft hand-off" which allows a mobile phone to be in communication with up to 6 base stations simultaneously, a type of "same-frequency handover". The incoming packets are compared for quality, and the best one is selected. This enables CDMA to perform in areas where TDMA calls would be dropped. To meet Wikipedias quality standards, this article or section may require cleanup. ... Universal Mobile Telecommunications System (UMTS) is one of the third-generation (3G) mobile phone technologies. ... Microcell Telecommunications is a Canadian wireless PCS telecommunications service provider. ...

A disadvantage of TDMA systems is that they create interference at a frequency which is directly connected to the timeslot length. This is the irritating buzz which can sometimes be heard if a GSM phone is left next to a radio or speakers. Another disadvantage is that the "dead time" between timeslots limits the potential bandwidth of a TDMA channel. This is why early efforts to incorporate timeslots into UMTS failed, leaving UMTS as a purely CDMA technology. The only country to continue pursuing TD-SCDMA (time division synchronous CDMA) is mainland China, perhaps because the government does not want to pay patent royalties to Qualcomm of the USA or licensing fees to the mainly European UMTS consortium. General Information Generically (as a multiplexing scheme), code division multiple access (CDMA) is any use of any form of spread spectrum by multiple transmitters to send to the same receiver on the same frequency channel at the same time without harmful interference. ...

Dynamic TDMA

In dynamic time division multiple access, a scheduling algorithm dynamically reserves a variable number of timeslots in each frame to variable bit-rate data streams, based on the traffic demand of each data stream. Dynamic TDMA is used in In computer science, a scheduling algorithm is the method by which threads or processes are given access to system resources, usually processor time. ...

• HIPERLAN/2 broadband radio access network.
• IEEE 802.16a WiMax
• Bluetooth
• The Packet radio multiple access (PRMA) method for combined circuit switched voice communication and packet data.
• TD-SCDMA

HIPERLAN is a WLAN standard. ... The IEEE 802. ... Bluetooth logo Bluetooth is an industrial specification for wireless personal area networks (PANs). ... TD-SCDMA (Time Division-Synchronous Code Division Multiple Access) is a 3G mobile telecommunications standard, being pursued in the Peoples Republic of China by the Chinese Academy of Telecommunications Technology (CATT), Datang and Siemens AG, in an attempt to develop home-grown technology and not be dependent on Western...

See also

• Channel access methods
• Time-division multiplex (TDM)
• Duplex (telecommunications) (FDD,TDD)