What is LTE Rach procedure?

What is LTE Rach procedure?

Random Access Procedure:- 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 syncronise with the network. In LTE a separate channel PRACH ( Physical Random Access Channel) is provided for initial access to the network.

What is CBRA and CFRA in LTE?

As in the case of LTE, the RA procedure can take two distinct forms: Contention-Based Random Access (CBRA) and Contention-Free Random Access (CFRA) procedures as shown below: In CBRA, the UE randomly selects an RA preamble from a pool of preambles shared with other UEs in the cell.

What is prach and Pusch?

The main 5G NR physical channels used for Uplink communication are the Physical uplink shared channel (PUSCH), the physical uplink control channel (PUCCH), and the Physical Random Access Channel (PRACH). Uplink signals such as DM-RS, PT-RS, and SRS are also supported.

What is preamble format in LTE?

When a UE transmit a PRACH Preamble, it transmits with a specific pattern and this specific pattern is called a “Signature”. In each LTE cell, total 64 preamble signatures are available and UE select randomly one of these signatures.

What is RACH root sequence?

The RACH Root. Sequence index indicates the first root sequence number that is to be used by. a UE for preamble generation. 25. This formula is applicable when Ncs unrestricted set and preamble format.

What is Msg1 and Msg2?

Msg1 : Random Access Preamble (RA) Msg2 : Random Access Response (RAR) Msg3 : RRC Connection Request.

What is Pdcch order?

PDCCH Order is a mechanism by which eNB force UE to initiate PRACH. This procedure usually happens when Network and UE briefly lost sync while in connected states and user data is available to be sent out on Network side.

What is Rach root sequence?

What is Pdcch?

The Physical Downlink Control Channel (PDCCH) is primarily used to carry scheduling information to individual UEs, i.e., resource assignments for uplink and downlink data and control information. The PDCCH is located in the first few OFDM symbols of a subframe.

What is Pucch and Pusch in LTE?

The LTE uplink physical layer has a triplet of physical channels; Physical Uplink Shared Channel (PUSCH), Physical Uplink Control Channel (PUCCH) and Physical Random Access Channel (PRACH). The PUSCH is used for transmitting user traffic data in multiplex with Uplink Control Information (UCI), if necessary.

What is preamble sequence?

preamble sequence The set of signals preceding genuine data in a transmission. The term is most commonly used in connection with Ethernet (CSMA/CD) signaling, where each packet is preceded by a sequence of alternate 1s and 0s to allow the receiving system to synchronize its local clock with that of the transmitter.

Why RACH is used in LTE?

Machine-to-machine communication (M2M) is a technology to provide interaction among network devices without human intervention. Due to infrastructure characteristics, LTE networks are highly expected to become the deployment network of M2M devices.

What is RSI collision in LTE?

Source cells that had two or more neighbor cells with equal PCI in the same frequency band between themselves were labeled as having a PCI confusion. Source cells that had neighbor cells with equal RSI in the same frequency band, were labeled as having a RSI collision.

What is MSG2 in LTE?

ii)The second message (MSG2) is RAR, with which the eNB transmits the message to the device if there is no collision. This message includes a temporary cell-radio network temporary identifier (TC-RNTI) and a timing advance (TA) command (i.e., to adjust the device transmit timing).

What is Pdcch and Pdsch?

PDSCH — physical downlink shared channel. The PDSCH carries user data and paging information to the terminal. PDCCH — physical downlink control channel. The PDCCH conveys control information, scheduling decisions for PDSCH reception, and for scheduling grants enabling transmission on the PUSCH.

What is Pdcch format?

What is the Pdcch in LTE?

What is the role of Pdcch channel in LTE?

PDCCH ( Physical downlink Control Channel ) :- This channel carries the control information about the data being transmitted on the current subframe and the information about the resources which UE need to use for the uplink data.

What is root sequence index in LTE?

The Logical Root Sequence Index is the value of RACH_ROOT_SEQUENCE which is the logical index for the Zadoff-Chu sequence used for PRACH preamble generation.

What is PCI and RSI in LTE?

This work focuses on applying supervised techniques for detecting two known LTE network conflicts, namely Physical Cell Identity (PCI) conflicts and Root Sequence Index (RSI) collisions.

What is RA Rnti?

RA-RNTI : It stands for Random Access RNTI. Used for PRACH Response. C-RNTI : It stands for Cell RNTI. Used for the transmission to a specific UE after RACH.

What is LTE Pdcch?

PDCCH is a physical channel that carries downlink control information (DCI) and it has characteristics as described below. Mapped to the first L OFDM symbols in every downlink subframe. Number of the symbols (L) for PDCCH can be 1,2, or 3. ( This ‘L’ value is informed to UE by PCFICH)

How do you decode Pdcch?

The UE finds the PDCCH specific to it by monitoring a set of PDCCH candidates (a set of consecutive CCEs on which a PDCCH could be mapped) in every subframe. The UE uses its Radio Network Temporary Identifier (RNTI) to try and decode candidates. The RNTI is used to demask a PDCCH candidate’s CRC.

What is DCI and Pdcch?

The Downlink Control Information (DCI) is transmitted through the Physical Downlink Control Channel (PDCCH) and includes information about the DL-SCH resource allocation (the set of resource blocks containing the DL-SCH), transport format and information related to the DL-SCH Hybrid Automatic Repeat reQuest (ARQ).

What is PRACH mask index in LTE?

The PRACH mask index identifies which PRACH resources the UE is allowed to use for its access attempt (see 36.32, section 7.3). More specifically, the mask defines in whichPRACH (or PRACHs) within a frame a UE can transmit a Random Access Preamble.

What is pdcch order in LTE?

PDCCH Order is the mechanism. The role of PDCCH Order in normal LTE operation can be illustrated as shown below. (I think the overall description of PDCCH order is much better described in PDCCH Order in LTE at Simpletechpost). You would find statement of PDCCH order in 3GPP as shown below. 36.212 – says

What is the role of pdcch in LTE throughput optimization?

The LTE throughput optimization procedure described in this article requires PDCCH enhancements. The general idea is that the LTE subframe is made up of PDCCH and PDSCH as explained in my article LTE Frame Structure Made Simple. The PDCCH is used for control information while the PDSCH carries the actual data.

What is pdcch order?

In other words, PDCCH Order is a special form of DCI 1A with the fields as described below (NOTE : 36.212 – says “Format 1A is used for random access procedure initiated by a PDCCH order only if format 1A CRC is scrambled with C-RNTI and all the remaining fields are set as follows:”) . Field Nunmber of Bits Value for PDCCH Order

How many CCE for pdcch and phich?

The number of CCE depends on channel BW and number of OFDMA symbols allocated for PDCCH. The table represents the same assuming no quadruplets have been allocated to PHICH and 4×4 MIMO is not used.