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1880 results about "Hybrid automatic repeat request" patented technology

Hybrid automatic repeat request (hybrid ARQ or HARQ) is a combination of high-rate forward error-correcting coding and 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). Receivers detecting a corrupted message will request a new message from the sender. In Hybrid ARQ, the original data is encoded with a forward error correction (FEC) code, and the parity bits are either immediately sent along with the message or only transmitted upon request when a receiver detects an erroneous message. The ED code may be omitted when a code is used that can perform both forward error correction (FEC) in addition to error detection, such as a Reed–Solomon code. The FEC code is chosen to correct an expected subset of all errors that may occur, while the ARQ method is used as a fall-back to correct errors that are uncorrectable using only the redundancy sent in the initial transmission. As a result, hybrid ARQ performs better than ordinary ARQ in poor signal conditions, but in its simplest form this comes at the expense of significantly lower throughput in good signal conditions. There is typically a signal quality cross-over point below which simple hybrid ARQ is better, and above which basic ARQ is better.

Hybrid automatic repeat request transmission method based on polarization code

The invention discloses a hybrid automatic repeat request transmission method based on a polarization code. The hybrid automatic repeat request transmission method based on the polarization code comprises the following steps: after a coding bit sequence obtained after polarization coding is carried out to a sent information bit sequence is punched via a sending end, sending into a channel to be transmitted; decoding a received signal by a receiving end for CRC (cyclic redundancy check); if the received signal passes the check, feeding back an ACK (acknowledgement character) signal to the sending end, and otherwise, sending a NACK (negative acknowledgement) signal; if the sending end receives the NACK signal, sending one part of uncoded information bits to a receiving end again; according to the coding bit received for the first time and a newly-received information bit, decoding again by the receiving end; if a decoding result still does not pass the CRC, sending the other part of uncoded information bits to the receiving end again by the sending end; according to the coding bit received for the first time, the information bit received in the previous time and the newly-received information bit, decoding again by the receiving end; continuously executing the process; and finishing one whole transmission process until the sending end receives the ACK signal or the number of sending times reaches a preset maximum value.
Owner:BEIJING UNIV OF POSTS & TELECOMM

HARQ (Hybrid Automatic Repeat Request) signal transmitting method and device and receiving method and device based on polar codes

ActiveCN105743621AIncrease the probability of correct decodingLower the average number of sendsError prevention/detection by using return channelError correction/detection using linear codesCommunications systemComputer science
The embodiment of the invention provides an HARQ (Hybrid Automatic Repeat Request) signal transmitting method and device and receiving method and device based on polar codes. When transmitting is carried out at a time, when it is judged that there are surplus data blocks, one data block is selected out from the surplus data blocks as an initial transmitting information sequence; the combination of first sub-sequences and second sub-sequences corresponding to negative acknowledge signals in a first retransmitting control queue is determined as a retransmitting information sequence, wherein the first sub-sequences and the second sub-sequences are stored in a transmitting cache queue; the initial transmitting information sequence and the retransmitting information sequence are determined as to-be-transmitted information sequences; one first sub-sequence of the determined to-be-transmitted information sequences is stored in the transmitting cache sequence; polar coding is carried out to the to-be-transmitted information sequences; and the to-be-transmitted information sequences are transmitted. The accurate decoding probability of the information sequences failed to be transmitted for former M times is improved; therefore, the throughput of the communication system is improved; the average transmitting and receiving times before the accurate decoding is carried out to the to-be-transmitted information sequences is reduced; and therefore, the transmission delay of the communication is reduced.
Owner:BEIJING UNIV OF POSTS & TELECOMM
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