Bandwidth efficient QAM schemes for Rayleigh fading channels

Webb, William; Hanzo, Lajos; Steele, R.

doi:10.1049/ip-i-2.1991.0023

Cited by 150 publications

(106 citation statements)

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“…Moreover, the differential encoding applied to the ring-amplitudes in (31) is the same as in classic DAPSK [3]- [5], which is given by Γ n = γ n−1 Γ n−1 . The L A -level transmitted ring-amplitude and data-carrying ringamplitude are given by Γ n = α µn √ β and γ n−1 = αǎ, respectively.…”

Section: A Differential and Absolute Amplitude Encodingmentioning

confidence: 99%

“…Proposition 5: An optimized diversity product for a DSTM scheme using PSK also results in an optimized diversity product 3 for its star QAM counterpart of DSTM using DASK/ASK.…”

Section: B Maximum-likelihood Differential Detection (Ml-dd)mentioning

confidence: 99%

“…In Single-Input Single-Output (SISO) channels, Differential Phase Shift Keying (DPSK) [1], [2], Differential Amplitude Phase Shift Keying (DAPSK) [3]- [5] and Absolute-amplitude Differential Phase Shift Keying (ADPSK) [4]- [6] constitute low-complexity alternatives to coherent PSK/QAM schemes. In Multiple-Input Multiple-Output (MIMO) channels, Differential Space-Time Modulation (DSTM) that dispenses with high-complexity channel estimation has also attracted substantial research interests.…”

Section: Introductionmentioning

confidence: 99%

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Single-RF Index Shift Keying Aided Differential Space–Time Block Coding

Rajashekar

Ishikawa

et al. 2018

IEEE Trans. Signal Process.

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Abstract-We propose a new single-RF Differential Space-Time Block Coding using Index Shift Keying (DSTBC-ISK), which is the first in the family of Differential Space-Time Modulation (DSTM) schemes that can simultaneously achieve the following three imperative objectives of (1) forming a finite-cardinality transmit-signals set under the matrix multiplications of differential encoding; (2) retaining a single-stream ML detection complexity that does not grow with the constellation size; (3) offering a beneficial transmit diversity gain over the recently developed Differential Spatial Modulation (DSM). In order to make a fair comparison, we also conceive a low-complexity single-stream detector for DSM, which does not impose any performance loss in comparison to the existing solutions in open literature. Furthermore, in order to improve the performance of finitecardinality DSTM schemes at higher throughputs, we propose to generalize both Differential Amplitude Shift Keying (DASK) and Amplitude Shift Keying (ASK), which form the generic multilevel-ring star QAM constellation that subsumes the existing two/four-level-ring DASK solutions as special cases. Although the DASK approach has been popularly used in DSTM schemes, we demonstrate that our generalized ASK technique achieves a higher capacity and a better performance in channel coding assisted systems. Moreover, since the employment of star QAM constellations imposes the ring-amplitude dependent signal power problem for detection, we further develop bespoke MaximumLikelihood (ML), Minimum Mean Squared Error (MMSE) and Least Square (LS) detectors for DSTM using DASK/ASK, which exhibit different performance versus complexity tradeoffs. Our simulation results demonstrate that the proposed DSTBC-ISK is capable of achieving substantial diversity gains over DSM without eroding its low transceiver complexity.

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Section: A Differential and Absolute Amplitude Encodingmentioning

confidence: 99%

“…Proposition 5: An optimized diversity product for a DSTM scheme using PSK also results in an optimized diversity product 3 for its star QAM counterpart of DSTM using DASK/ASK.…”

Section: B Maximum-likelihood Differential Detection (Ml-dd)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Single-RF Index Shift Keying Aided Differential Space–Time Block Coding

Rajashekar

Ishikawa

et al. 2018

IEEE Trans. Signal Process.

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“…For this reason, typically Star QAM constellations are preferred for DQAM design. Furthermore, the classic Differential Amplitude Phase Shift Keying (DAPSK) was proposed by Webb et al [4] in 1991, where differential encoding was invoked for both the Star QAM ring-amplitude and phase. In 2000, Fischer et al [2] carried out the capacity comparison of ADPSK, of DAPSK and of their twisted-constellationbased counterparts both in AWGN channels and in quasi-static fading channels.…”

Section: Introductionmentioning

confidence: 99%

“…The performance of the CDD aided DAPSK was compared to that of the coherent QAM in [5]- [7], where the DAPSK was shown to be particularly advantageous, when its coherent QAM counterpart suffered from a realistic channel estimation error. However, it was observed in [4] that the performance of CDD aided DAPSK degrades and eventually an error floor is formed in Rayleigh fading channels, when the Doppler frequency is increased. In order to further improve the CDD's performance, the classic Decision-Feedback Differential Detection (DFDD) that was originally proposed for DPSK in [8], [9] was further developed for DAPSK in [10]- [12].…”

Section: Introductionmentioning

confidence: 99%

Multiple-Symbol Differential Sphere Detection and Decision-Feedback Differential Detection Conceived for Differential QAM

Hanzo

2016

IEEE Trans. Veh. Technol.

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Abstract-Multiple-Symbol Differential Sphere Detection (MS-DSD) relies on the knowledge of channel correlation. More explicitly, for Differential PSK (DPSK), the transmitted symbols' phases form a unitary matrix, which can be separated from the channel's correlation matrix by the classic Multiple-Symbol Differential Detection (MSDD), so that a lower triangular matrix extracted from the inverted channel correlation matrix is utilized for the MSDSD's sphere decoding. However, for Differential QAM (DQAM), the transmitted symbols' amplitudes cannot form a unitary matrix, which implies that the MSDD's channel correlation matrix becomes amplitude-dependent and remains unknown, unless all the data-carrying symbol amplitudes are detected. In order to tackle this open problem, in this paper, we propose to determine the MSDD's non-constant amplitudedependent channel correlation matrix with the aid of a sphere decoder, so that the classic MSDSD algorithms that were originally conceived for DPSK may also be invoked for DQAM detection. As a result, our simulation results demonstrate that the MSDSD aided DQAM schemes substantially outperform their DPSK counterparts. However, the price paid is that the detection complexity of MSDSD is also significantly increased. In order to mitigate this, we then propose a reduced-complexity MSDSD search strategy specifically conceived for DQAM constellations, which separately map bits to their ring-amplitude index and phase index. Furthermore, the classic Decision-Feedback Differential Detection (DFDD) conceived for DQAM relies on a constant channel correlation matrix, which implies that these DFDD solutions are sub-optimal and they are not equivalent to the optimum MSDD operating in decision-feedback mode. With the advent for solving the open problem of MSDSD aided DQAM, we further propose to improve the conventional DFDD aided DQAM solutions in this paper.

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