What happens when RACH fail?
What happens when RACH fail?
A RACH Response (RAR) with respect to the RACH Preamble transmitted in step 1) is received. If the RACH Response reception fails, the Preamble Transmission counter value is increased by 1, and a back-off time is applied if necessary, and the process returns back to step 1).
What is CBRA and CFRA?
In CBRA, the UE randomly selects an RA preamble from a pool of preambles shared with other UEs in the cell. In CFRA, the UE uses a dedicated preamble provided by the network specifically to this UE via RRC signaling or PDCCH order.
What is group A and group B preamble?
The preambles in Random Access Preamble group A are the preambles (0 to sizeOfRAPreamblesGroupA – 1) and, if it exists, the preambles in Random Access Preamble group B are (the preambles sizeOfRA-PreamblesGroupA to numberOfRA-Preambles – 1) from the set of 64 preambles.
What is Rach attempt?
A random-access channel (RACH) is a shared channel used by wireless terminals to access the mobile network (TDMA/FDMA, and CDMA based network) for call set-up and bursty data transmission.
What is RACH failure LTE?
If the UE does not receive a response within the random access window or fails to verify the response, the response fails. In this case, if the number of random access attempts is smaller than the upper limit, the UE retries random access. Otherwise, random access fails.
What is RACH used for?
A random-access channel (RACH) is a shared channel used by wireless terminals to access the mobile network (TDMA/FDMA, and CDMA based network) for call set-up and bursty data transmission. Whenever mobile wants to make an MO (Mobile Originating) call it schedules the RACH.
What is the Rach procedure in LTE?
In order to be synchronized with the network, RACH procedure is used.Suppose a UE wants to access the network, so first it will try to attach or synchronize with the network. In LTE a separate channel PRACH (Physical Random Access Channel) is provided for initial access to the network.
What is the use of Prach channel in LTE?
LTE PRACH Channel-Physical Random Access Channel. This channel is used to carry random access preambles used for initiation of random access procedure. The basic structure is mentioned in the figure. As shown a random access preamble includes a CP, a sequence and a guard time. This carries the random access preamble.
What is the purpose of Rach transport channel?
This channel is used to carry random access preambles used for initiation of random access procedure. The basic structure is mentioned in the figure. As shown a random access preamble includes a CP, a sequence and a guard time. This carries the random access preamble. The RACH transport channel is mapped to this.
What is a random access preamble in LTE?
As shown a random access preamble includes a CP, a sequence and a guard time. This carries the random access preamble. The RACH transport channel is mapped to this. • There are 4 different RA (random access) preamble formats defined in LTE FDD specifications.
