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A Scalable LDPC Coding Scheme for Adaptive HARQ Techniques

Madeira, J. ; Viana, J. ; Guerreiro, J. ; Dinis, R.

A Scalable LDPC Coding Scheme for Adaptive HARQ Techniques, Proc IEEE 95th Vehicular Technology Conference: VTC2022-Spring, Helsinki, Finland, Vol. , pp. - , June, 2022.

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Abstract
In wireless communication systems, the achievable
data rates are always dependent on the characteristics of the
wireless channel. Although a system is designed for an expected
channel link quality, the channel may deteriorate for certain
periods of time due to the changing nature of the propagation
environment. A weak channel may lead to transmission errors,
which can be corrected by employing Hybrid Automatic Repeat
Requests (HARQ). In particular, type II HARQ protocols have
become an appealing option since they only involve the transmission of additional parity bits, instead of repeating the original
transmission. These additional parity bits can be obtained by
puncturing a low rate channel code. However, finding an optimum
pattern of puncturing for a specific code is non-trivial. In this
work, we propose a retransmission scheme that considers various
Low-Density Parity-Check (LDPC) codes of different rates that
can be concatenated to perform the encoding and decoding
operations, resulting in a lower encoding overhead for successful
transmissions, while maintaining efficient decoding. We show that
this technique can maintain high throughput and goodput, and
a low outage probability, even when the received signal power
is suddenly reduced due to the loss of the Line-of-sight (LOS)
component.