What Is HARQ In LTE?

What is HARQ RTT timer?

HARQ RTT Timer specifies the minimum amount of subframe(s) duration from the time new transmission is received and before the UE can expect a retransmission of the same packet.

This timer is fixed and not configured by RRC.

For FDD the HARQ RTT Timer is set to 8 subframes..

What is LTE prach?

PRACHPhysical Random Access Channel is the Physical Random Access Channel and is used by UEs to request an uplink allocation from the base station. In the frequency domain, PRACH spans 6 resource blocks of spectrum. The frequency location of PRACH is determined by upper layers. …

How does DRX work?

DRX is a mechanism in which UE gets into sleep mode for a certain period of time and wake up for another period of time. It sounds good.

What is msg3 buffer?

What is msg3 buffer? When msg3 is transmitted during initial attach it will be moved to HARQ buffer to handle the retransmission. So msg3 buffer is used to store when UE has msg3. Also MSG3 buffers is sent on SRB0 in initial time.

What is Harq in 5g?

A technique referred to as Hybrid Automatic Repeat ReQuest (HARQ) is employed for error detection and correction. In a standard Automatic Repeat ReQuest (ARQ) method, error detection bits are added to data to be transmitted. In Hybrid ARQ, error correction bits are also added.

What is HARQ ACK codebook?

Number of HARQ Bits : 1 bit per CBG(Codeblock Group). In this case, Usually 1 TB carries multiple CBG, so multiple bits are allocated for one TB. < Case 5 > Condition : HARQ-ACK-codebook=semi-static.

What is incremental redundancy?

Incremental redundancy (IR) transmits increments of redundant bits after errors are observed. IR adaptively changes an effective data rate based on the results of actual transmissions.

How does ARQ correct error?

Automatic repeat request (ARQ), also known as automatic repeat query, is an error-control method for data transmission that uses acknowledgements (messages sent by the receiver indicating that it has correctly received a packet) and timeouts (specified periods of time allowed to elapse before an acknowledgment is to be …

What is difference between ARQ and HARQ?

The HARQ is the use of conventional ARQ along with an Error Correction technique called ‘Soft Combining’, which no longer discards the received bad data (with error). With the ‘Soft Combining’ data packets that are not properly decoded are not discarded anymore.

What is redundancy version in LTE?

The redundancy version tells the UE, about amount of redundancy added into the codeword while turbo encoding. There can be 4 different redundancy versions in LTE corresponding to new transmission, 1st, 2nd or 3rd re-transmission. Number of bits = 2.

What is HARQ ACK?

Hybrid automatic repeat request (hybrid ARQ or HARQ) is a combination of high-rate forward error correction (FEC) and automatic repeat request (ARQ) error-control. In standard ARQ, redundant bits are added to data to be transmitted using an error-detecting (ED) code such as a cyclic redundancy check (CRC).

What is LTE Pucch?

PUCCHPhysical Uplink Control Channel is the Physical Uplink Control Channel and carries uplink control information including channel quality info, acknowledgements, and scheduling requests.

Which protocol is responsible for HARQ and scheduling?

Finally, the Medium Access Control (MAC) sublayer provides Hybrid-ARQ (HARQ) and is responsible for the functionality that is required for medium access, such as scheduling operation and random access. The overall PDCP/RLC/MAC architecture for downlink and uplink is shown in Figs. 3.1 and 3.2, respectively.

What is DRX switch?

DRX is a technique that allows the mobile station to power down significant amounts of its internal circuitry for a high percentage of the time when it is in the idle mode. The period of time when the mobile station will be powered down is commonly called the “Sleep mode”.