Optimal Combining Schemes for MIMO Systems with Hybrid ARQ

Jang, E.W.; Lee, Jung Won; Lou, Hui‐Ling; Cioffi, J.M.

doi:10.1109/isit.2007.4557560

Cited by 24 publications

(37 citation statements)

References 3 publications

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“…Actually, the soft information Mas (t) jk (S) for each bit can be calculated by other ways. For example, in the LLR combining scheme [6], log-likelihood-probability-ratio for each bit is used. If the likelihood probability is invoked as a form of bit-level BPA, the conventional LLR combining is demonstrated to be equivalent to the proposed DS combining scheme with details as below.…”

Section: Mas (T)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…In [4,5], authors developed effective HARQ strategies at the transmitter in order to improve the system reliability. Contrariwise, both [6,7] discussed combining algorithms at the receiver.Three linear combining schemes [8], selection combining (SC), equal-gain combining (EGC), and maximal ratio combining (MRC), entail various trade-offs between performance and complexity, and comparatively MRC is deemed to be superior to the others by outputting the maximum signal-to-noise (SNR) ratio in SISO systems. Jang et al [6] proposed an optimal combining scheme for MIMO systems with HARQ, which can be used in both symbol-level and bit-level.…”

mentioning

confidence: 99%

“…Jang et al [6] proposed an optimal combining scheme for MIMO systems with HARQ, which can be used in both symbol-level and bit-level. However, the complexity imposed in [6] increases exponentially with the number of both bits per symbol and transmit antennas [7] proposed an improved LLR combining scheme, invoking a new LLR calculation method. The traditional combining schemes are developed on the basis of Bayesian theory.…”

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confidence: 99%

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DSC and universal bit-level combining for HARQ systems

Xia

Long

2011

J Wireless Com Network

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This paper proposes a Dempster -Shafer theory based combining scheme for single-input single-output (SISO) systems with hybrid automatic retransmission request (HARQ), referred to as DSC, in which two methods for soft information calculations are developed for equiprobable (EP) and non-equiprobable (NEP) sources, respectively. One is based on the distance from the received signal to the decision candidate set consisting of adjacent constellation points when the source bits are equiprobable, and the corresponding DSC is regarded as DSC-D. The other is based on the posterior probability of the transmitted signals when the priori probability for the NEP source bits is available, and the corresponding DSC is regarded as DSC-APP. For the diverse EP and NEP source cases, both DSCD and DSC-APP are superior to maximal ratio combining, the so-called optimal combining scheme for SISO systems. Moreover, the robustness of the proposed DSC is illustrated by the simulations performed in Rayleigh channel and AWGN channel, respectively. The results show that the proposed DSC is insensitive to and especially applicable to the fading channels. In addition, a DS detection-aided bit-level DS combining scheme is proposed for multiple-input multiple-output-HARQ systems. The bit-level DS combining is deduced to be a universal scheme, and the traditional log-likelihood-ratio combining is a special case when the likelihood probability is used as bit-level soft information.Keywords: Basic probability assignment (BPA), Bit-level combining, Dempster -Shafer (D -S) evidence theory, Hybrid automatic retransmission request (HARQ), Multiple-input multiple-output (MIMO), Maximum-ratio combining (MRC) I IntroductionA concern in packet data communication systems is how to control the transmission errors caused by the channel noise and interferences so that packets can be transmitted reliably. Automatic retransmission request (ARQ), as a fundamental approach, is intended to ensure an extremely low packet error rate. The efficiency of the system can be improved if the ARQ is combined with a forward-error-correcting (FEC) code, referred to as HARQ, which includes Chase combining [1] and incremental redundancy (IR) [2]. There are many HARQ strategies: including separating the HARQ process into HARQ sub-processes that operate over an isolated pairing of a transmitter and receiver antenna [3]; the constellation rearrangement technique [4] and the bit rearrangement scheme [5] that can provide a kind of diversity for performance improvement. In [4,5], authors developed effective HARQ strategies at the transmitter in order to improve the system reliability. Contrariwise, both [6,7] discussed combining algorithms at the receiver.Three linear combining schemes [8], selection combining (SC), equal-gain combining (EGC), and maximal ratio combining (MRC), entail various trade-offs between performance and complexity, and comparatively MRC is deemed to be superior to the others by outputting the maximum signal-to-noise (SNR) ratio in SISO systems. Jang e...

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Section: Mas (T)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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DSC and universal bit-level combining for HARQ systems

Xia

Long

2011

J Wireless Com Network

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“…In [14], we proposed a near ML block detection with recursive QR packet combining and M-algorithm for single-user (SU)-MIMO. We showed that the recursive QR packet combining can significantly increase the throughput performance of SU-MIMO HARQ compared to the bit-level log likelihood ratio (LLR) packet combining [15]. Since a single channel encoder is assumed in [15], the received signal always consists of either new packet or retransmitted packet.…”

Section: Introductionmentioning

confidence: 99%

Recursive QR packet combining for uplink single-carrier multi-user MIMO HARQ using near ML detection

Yamamoto

Adachi

Sun

et al. 2012

2012 8th International Wireless Communications and Mobile Computing Conference (IWCMC)

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Abstract-QR decomposition based near maximum likelihood (ML) block detection significantly improves the transmission performance of uplink single-carrier (SC) multi-user multipleinput multiple-output (MU-MIMO). Hybrid automatic repeat request (HARQ) is an indispensable error control technique for high quality packet data transmission. The achievable diversity gain of HARQ depends on the packet combining strategy. In uplink MU-MIMO HARQ, received signal may consist of new packets and retransmitted packets as retransmission for each user acts independently. In this paper, a recursive QR packet combining scheme suitable for uplink SC MU-MIMO HARQ is proposed, which takes into account the number of retransmissions for each user in the detection order. The proposed scheme helps reduce the computational complexity and storage requirement significantly. Moreover, it improves the packet error rate (PER) performance significantly over the conventional bit-level log likelihood ratio (LLR) packet combining, as shown by our computer simulation results.

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