Timing advance

Timing advance

In the GSM cellular mobile phone standard, timing advance value corresponds to the length of time a signal from the mobile phone takes to reach the base station. GSM uses TDMA technology in the radio interface to share a single frequency between several users, assigning sequential timeslots to the individual users sharing a frequency. Each user transmits periodically for less than one-eighth of the time within one of the eight timeslots. Since the users are various distances from the base station and radio waves travel at the finite speed of light, the precise time at which the phone is allowed to transmit a burst of traffic within a timeslot must be adjusted accordingly. Timing Advance (TA) is the variable controlling this adjustment.

Technical Specifications 3GPP TS 05.10 and TS 45.010 describe the TA value adjustment procedures. The TA value is normally between 0 and 63, with each step representing an advance of one symbol period (approximately 3.69 microseconds). With radio waves travelling at about 300,000,000 metres per second (that is 300 metres per microsecond), one TA step then represents a change in round-trip distance (twice the propagation range) of about 1,100 metres. This means that the TA value changes for each 550-metre change in the range between a mobile and the base station.

A continually adjusted TA value avoids interference to and from other users in adjacent timeslots, thereby minimising data loss and maintaining call quality.

Timing Advance is significant for privacy and communications security, as its combination with other variables can allow locating and tracking the mobile phone user.

External links

* [http://www.3gpp.org 3GPP The current standardisation body for GSM with free standards available] .
* [http://www.3gpp.org/ftp/Specs/html-info/0510.htm 3GPP TS 05.10 Radio Subsystem Synchronization] (for Phase 1, Phase 2, R96, R97, R98, R99).
* [http://www.3gpp.org/ftp/Specs/html-info/45010.htm 3GPP TS 45.010 Radio Subsystem Synchronization] (for Rel-4, 5, 6).


Wikimedia Foundation. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • Timing Advance — (TA) ist ein Wert, der im GSM Standard zur Synchronisation zwischen Uplink und Downlink verwendet wird. Der Wert gibt (in Bitdauern von ca. 3,7 μs) den Zeitversatz an, um den eine Mobilstation früher senden muss, damit unter Berücksichtigung …   Deutsch Wikipedia

  • Timing Advance — Eine der goeßeren Gemeinheiten innerhalb GSM ist Timing Advance. Dieser Wert drückt (indirekt) die Länge des Wegs aus, den die Funkwellen vom Telefon zur Basisstation nehmen. Nämlich: Das Zeitschema in GSM ist so eng gewählt, daß das Telefon sein …   Acronyms

  • Timing Advance — Eine der größeren Gemeinheiten innerhalb GSM ist Timing Advance. Dieser Wert drückt (indirekt) die Länge des Wegs aus, den die Funkwellen vom Telefon zur Basisstation nehmen. Nämlich: Das Zeitschema in GSM ist so eng gewählt, daß das Telefon sein …   Acronyms von A bis Z

  • Timing belt — For other belts, see Belt (disambiguation). Timing belt Timi …   Wikipedia

  • advance — [1] The act of changing the ignition timing so that the spark occurs earlier in the cycle. The opposite is retard. [2] It may refer to the device which makes this adjustment. Also see automatic advance centrifugal advance electronic spark advance …   Dictionary of automotive terms

  • Ignition timing — in an internal combustion engine is the process of setting the time that a spark will occur in the combustion chamber (during the power stroke) relative to piston position and crankshaft angular velocity. Setting the correct ignition timing is… …   Wikipedia

  • Time advance — Saltar a navegación, búsqueda Time advance es un sistema de sincronización entre la estación base (BS) y la estación móvil (MS) necesario en las redes celulares que utilizan TDMA como método de acceso al medio y tienen una gran cobertura.… …   Wikipedia Español

  • orifice spark advance control — (OSAC) a device used by Chrysler to apply vacuum advance over a period of time. By limiting the timing advance rate, NOx is reduced …   Dictionary of automotive terms

  • vacuum advance — A mechanism on the side of the distributor that automatically varies the instant at which the spark occurs as a function of intake manifold vacuum. Vacuum advance provides the additional advance that is needed when the engine is operating at part …   Dictionary of automotive terms

  • Variable valve timing — Variable valve timing, or VVT, is a generic term for an automobile piston engine technology. VVT allows the lift or duration or timing (some or all) of the intake or exhaust valves (or both) to be changed while the engine is in operation. Two… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”