Random Access Channel
Encyclopedia
Random Access Channel (RACH) is used in mobile phone
s 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.
Random Access Channel is a shared channel that is used by Wireless Access terminals to Access the Access Network(TDMA/FDMA,and CDMA based network) especially for initial Access and Bursty data transmission.
A key feature of a Random Access Channel is that messages are not scheduled (compared to for example a "Dedicated Channel" in UMTS, that is assigned exclusively to one user at a time). There is no certainty, that only a single device makes a connection attempt at one time, and collisions can result.
Mobile phone
A mobile phone is a device which can make and receive telephone calls over a radio link whilst moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile network operator...
s or other wireless device on a TDMA-based network
Time division multiple access
Time division multiple access is a channel access method for shared medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots. The users transmit in rapid succession, one after the other, each using its own time slot. This...
when it needs to get the attention of a base station
Base station
The term base station can be used in the context of land surveying and wireless communications.- Land surveying :In the context of external land surveying, a base station is a GPS receiver at an accurately-known fixed location which is used to derive correction information for nearby portable GPS...
in order to initially synchronize its transmission with the base station.
Random Access Channel is a shared channel that is used by Wireless Access terminals to Access the Access Network(TDMA/FDMA,and CDMA based network) especially for initial Access and Bursty data transmission.
A key feature of a Random Access Channel is that messages are not scheduled (compared to for example a "Dedicated Channel" in UMTS, that is assigned exclusively to one user at a time). There is no certainty, that only a single device makes a connection attempt at one time, and collisions can result.