Iterative Soft-MMSE Detection Aided AFDM and OTFS
Iterative Soft-MMSE Detection Aided AFDM and OTFS
Affine Frequency Division Multiplexing (AFDM) has attracted substantial research interest due to its implementational similarity to Orthogonal Frequency-Division Multiplexing (OFDM), whilst attaining comparable performance to Orthogonal Time Frequency Space (OTFS). Hence, we embark on an in-depth performance characterisation of coded AFDM and of its equivalent OTFS counterpart. Soft-Minimum Mean Square Error (MMSE) reception taking into account a priori probabilities in the weighting matrix is applied in conjunction with Recursive Systematic Convolutional (RSC)- and RSC-Unity Rate Convolutional (URC) coding to AFDM. Iterative decoding convergence analysis is carried out with the aid of the powerful semi-analytical tool of EXtrinsic Information Transfer (EXIT) chart, and its Bit Error Rate (BER) performance is compared to OFDM and to the equivalent OTFS configurations.
As there are no consistent configurations of AFDM and OTFS utilised in the literature to compare their relative performances, two AFDM configurations and three OTFS configurations are considered. The results show that the BER of AFDM is lower than that of the equivalent OTFS configurations at high Energy per bit over Noise power (Eb /N0 ) for small system matrix dimensions, for a low number of iterations, and for high code rates. In all other cases, the BER of AFDM is shown to be similar to that of its equivalent OTFS configurations. Given that the RSC BER performance fails to improve beyond two iterations, this solution is recommended for low-complexity transceivers. By contrast, if the extra complexity of the RSC-URC aided transceiver is affordable, an extra Eb /N0 gain of 1.8 dB may be attained at a BER of 10−5 and a code rate of 0.5.
Affine Frequency Division Multiplexing, Orthogonal Frequency-Division Multiplexing, Orthogonal Time Frequency Space, Recursive Systematic Convolutional Codes, Soft-Minimum Mean Square Error, Unity Rate Convolutional codes
2944-2959
Hawkins, Hugo
5f1b37da-dbc7-4edc-9dc4-046b9ecb836b
Xu, Chao
5710a067-6320-4f5a-8689-7881f6c46252
Yang, Lie-Liang
ae425648-d9a3-4b7d-8abd-b3cfea375bc7
Hanzo, Lajos
66e7266f-3066-4fc0-8391-e000acce71a1
22 October 2025
Hawkins, Hugo
5f1b37da-dbc7-4edc-9dc4-046b9ecb836b
Xu, Chao
5710a067-6320-4f5a-8689-7881f6c46252
Yang, Lie-Liang
ae425648-d9a3-4b7d-8abd-b3cfea375bc7
Hanzo, Lajos
66e7266f-3066-4fc0-8391-e000acce71a1
Hawkins, Hugo, Xu, Chao, Yang, Lie-Liang and Hanzo, Lajos
(2025)
Iterative Soft-MMSE Detection Aided AFDM and OTFS.
IEEE Open Journal of Vehicular Technology, 6, .
(doi:10.1109/OJVT.2025.3623883).
Abstract
Affine Frequency Division Multiplexing (AFDM) has attracted substantial research interest due to its implementational similarity to Orthogonal Frequency-Division Multiplexing (OFDM), whilst attaining comparable performance to Orthogonal Time Frequency Space (OTFS). Hence, we embark on an in-depth performance characterisation of coded AFDM and of its equivalent OTFS counterpart. Soft-Minimum Mean Square Error (MMSE) reception taking into account a priori probabilities in the weighting matrix is applied in conjunction with Recursive Systematic Convolutional (RSC)- and RSC-Unity Rate Convolutional (URC) coding to AFDM. Iterative decoding convergence analysis is carried out with the aid of the powerful semi-analytical tool of EXtrinsic Information Transfer (EXIT) chart, and its Bit Error Rate (BER) performance is compared to OFDM and to the equivalent OTFS configurations.
As there are no consistent configurations of AFDM and OTFS utilised in the literature to compare their relative performances, two AFDM configurations and three OTFS configurations are considered. The results show that the BER of AFDM is lower than that of the equivalent OTFS configurations at high Energy per bit over Noise power (Eb /N0 ) for small system matrix dimensions, for a low number of iterations, and for high code rates. In all other cases, the BER of AFDM is shown to be similar to that of its equivalent OTFS configurations. Given that the RSC BER performance fails to improve beyond two iterations, this solution is recommended for low-complexity transceivers. By contrast, if the extra complexity of the RSC-URC aided transceiver is affordable, an extra Eb /N0 gain of 1.8 dB may be attained at a BER of 10−5 and a code rate of 0.5.
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Iterative Soft-MMSE Detection Aided AFDM and OTFS
- Accepted Manuscript
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Iterative_Soft-MMSE_Detection_Aided_AFDM_and_OTFS
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Accepted/In Press date: 16 October 2025
Published date: 22 October 2025
Keywords:
Affine Frequency Division Multiplexing, Orthogonal Frequency-Division Multiplexing, Orthogonal Time Frequency Space, Recursive Systematic Convolutional Codes, Soft-Minimum Mean Square Error, Unity Rate Convolutional codes
Identifiers
Local EPrints ID: 506882
URI: http://eprints.soton.ac.uk/id/eprint/506882
ISSN: 2644-1330
PURE UUID: 3b720a71-c2d2-45eb-abca-42b74be7429a
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Date deposited: 19 Nov 2025 17:44
Last modified: 20 Nov 2025 03:00
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Contributors
Author:
Hugo Hawkins
Author:
Chao Xu
Author:
Lie-Liang Yang
Author:
Lajos Hanzo
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