Hybrid Automatic Repeat Query (HARQ) is an error correction technique that has become an integral part of most current broadband wireless standards such as IEEE 802.16 and 3GPP-LTE (Long Term Evolution). Although extensive studies have been made on the performance of HARQ, they usually assume perfect channel state information at the receiver. This paper addresses the performance of incremental ...

Packet services are dominant in future broadband wireless communications, where hybrid automatic repeat request (HARQ) is used for error control [1]. HARQ schemes combine error detection and forward error correction to make more efficient use of the channel. In type I HARQ, all the necessary parity bits are sent with each transmission. However, type II HARQ sends only the error detection parity...

A new hybrid automatic repeat request (HARQ)with variable spreading factor (VSF) suitable for multicarrier code division multiple access (MC-CDMA) is presented. A HARQ based on incremental redundancy strategy is considered. The throughput of MC-CDMA HARQ is a function of the frequency diversity gain, the coding gain and the intercode interference. To effectively exploit the frequency diversity ...

Presented paper describes and analyses HARQ (Hybrid Automatic Repeat Request) and pure ARQ schemes. We focus on selected HARQ techniques applied to IP protocol and also to LMS channel. The efficiency of HARQ scheme is compared with GBN schemes using different lengths of IP packets. We show that usage of smaller packets and hybrid schemes leads to an improved throughput. Differences between pure...

Reliability of data transmission is a fundamental problem in wireless communications. Fading in wireless channels causes the signal strength to vary at the receiver and this results in loss of data packets. To improve the reliability, automatic repeat request (ARQ) schemes were introduced. However these ARQ schemes suffer from a reduction in the throughput. To address the throughput reduction, ...

Recently orthogonal frequency division multiplexing (OFDM) has gained a lot of attention in mobile radio communications because of its ability to allow high data rate transmission in a severe frequency selective fading channel. Rate compatible punctured turbo coded hybrid ARQ (RCPT HARQ) has been found to give improved throughput performance in a DS-CDMA system. However the extent to which the ...

Skype, one of the popular VoIP applications, has its own redundancy mechanism to mitigate the impact of packet loss at the expense of additional bandwidth usage. However, the benefit of voice quality improvement through redundancy is reduced greatly in the case of consecutive loss of Skype packets. When Skype is running over wireless networks, the high likelihood of having consecutive packet lo...

Abstract MC-CDMA, a multicarrier modulation scheme based on code division multiple access (CDMA) is the most likely candidate for the next generation of mobile radio communications. Rate compatible punctured turbo coded hybrid ARQ (RCPT HARQ) has been found to give improved throughput performance in a DS-CDMA system. In this paper, we apply RCPT HARQ to an MC-CDMA system and evaluate by compute...

In this paper, we propose a cross-layer design which combines adaptive modulation and coding (AMC) at the physical layer with a hybrid automatic repeat request (HARQ) protocol at the data link layer to minimize the packet error rate (PER) and maximize the spectral efficiency. By using Markov model to predict the channel condition of next frame according to the second order statistics characteri...

Cooperative hybrid ARQ (HARQ) protocols have been widely studied in recent years and they were shown to provide higher efficiency than cooperative protocols. This paper proposes a joint design within which the HARQ protocol collaborates with the link adaptation functionality and the cooperative transmission scheme in order to adapt the behavior of the HARQ protocol to the QoS requirements of th...