Flexible Subcarrier Allocation for Interleaved Frequency Division Multiple Access

Shao, Yulin; Liew, Soung Chang

doi:10.1109/twc.2020.3008484

Cited by 19 publications

(19 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our companion paper [8] shows that when numbers of subcarriers requested by all end nodes are powers of 2, subcarrier allocation in IFDMA is no less efficient than in LFDMA and that full loading is possible. The main result is embodied in Proposition 1 below, which states that, provided the sum of the numbers of subcarriers requested by all end nodes do not exceed M , there exists a subcarrier allocation scheme that can satisfy the IFDMA evenly-spacedsubcarrier constraint.…”

Section: A Subcarrier Allocationmentioning

confidence: 99%

“…Proposition 1 (full loading is possible despite evenly-spaced-subcarrier constraint [8]). Consider an IFDMA system with M = 2 m subcarriers.…”

Section: A Subcarrier Allocationmentioning

confidence: 99%

“…The detector works 4 We note that the schematic of Fig. 4 also gives an interpretation as to why the bit-reversal subcarrier allocation algorithm works (see Section II or [8]). In the algorithm, a user is first allocated a set of "bins" with contiguous indexes.…”

Section: B Ifdma Detector Designmentioning

confidence: 99%

“…The bit-reversal subcarrier allocation scheme addresses Constraint 1. The details of the scheme, its variants, and their implications for resource allocation are treated comprehensively in our companion paper [8]. The main focus on this paper is on the transceiver designs.…”

mentioning

confidence: 99%

See 3 more Smart Citations

New Transceiver Designs for Interleaved Frequency Division Multiple Access

Liew

Shao

2019

Preprint

Self Cite

View full text Add to dashboard Cite

This paper puts forth a class of new transceiver designs for interleaved frequency division multiple access (IFDMA) systems. These transceivers are significantly less complex than conventional IFDMA transceiver. The simple new designs are founded on a key observation that multiplexing and demultiplexing of IFDMA data streams of different sizes are coincident with the IFFTs and FFTs of different sizes embedded within the Cooley-Tukey recursive FFT decomposition scheme. For flexible resource allocation, this paper puts forth a new IFDMA resource allocation framework called Multi-IFDMA, in which a user can be allocated multiple IFDMA streams. Our new transceivers are unified designs in that they can be used in conventional IFDMA as well as multi-IFDMA systems. Two other wellknown multiple-access schemes are localized FDMA (LFDMA) and orthogonal FDMA (OFDMA).In terms of flexibility in resource allocation, Multi-IFDMA, LFDMA, and OFDMA are on an equal footing. With our new transceiver designs, however, IFDMA has the following advantages (besides other known advantages not due to our new transceiver designs): 1) IFDMA/Multi-IFDMA transceivers are significantly less complex than LFDMA transceivers; in addition, IFDMA/Multi-IFDMA has better Peak-to-Average Power Ratio (PAPR) than LFDMA; 2) IFDMA/Multi-IFDMA transceivers and OFDMA transceivers are comparable in complexity; but IFDMA/Multi-IFDMA has significantly better PAPR than OFDMA.

show abstract

Section: A Subcarrier Allocationmentioning

confidence: 99%

“…Proposition 1 (full loading is possible despite evenly-spaced-subcarrier constraint [8]). Consider an IFDMA system with M = 2 m subcarriers.…”

Section: A Subcarrier Allocationmentioning

confidence: 99%

Section: B Ifdma Detector Designmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

New Transceiver Designs for Interleaved Frequency Division Multiple Access

Liew

Shao

2019

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…Distributed data aggregation in MAC for function computation can be realized in a digital fashion via traditional multiple-access technologies [18], [19] (e.g., TDMA, CDMA, OFDMA). Specifically, the values to be transmitted from the edge devices are first digitized and then transmitted over orthogonal links to the fusion center.…”

Section: Introductionmentioning

confidence: 99%

Bayesian Over-The-Air Computation

Shao¹,

Gündüz²,

Liew³

2021

Preprint

Self Cite

View full text Add to dashboard Cite

Analog over-the-air computation (OAC) is an efficient solution to a class of uplink data aggregation tasks over a multiple-access channel (MAC), wherein the receiver, dubbed the fusion center, aims to reconstruct a function of the data distributed at edge devices rather than the individual data themselves. Existing OAC relies exclusively on the maximum likelihood (ML) estimation at the fusion center to recover the arithmetic sum of the transmitted signals from different devices. ML estimation, however, is much susceptible to noise. In particular, in the misaligned OAC where there are channel misalignments among transmitted signals, ML estimation suffers from severe error propagation and noise enhancement. To address these challenges, this paper puts forth a Bayesian approach for OAC by letting each edge device transmit two pieces of prior information to the fusion center. Three OAC systems are studied: the aligned OAC with perfectly-aligned signals; the synchronous OAC with misaligned channel gains among the received signals; and the asynchronous OAC with both channelgain and time misalignments. Using the prior information, we devise linear minimum mean squared error (LMMSE) estimators and a sum-product maximum a posteriori (SP-MAP) estimator for the three OAC systems. Numerical results verify that, 1) For the aligned and synchronous OAC, our LMMSE estimator significantly outperforms the ML estimator. In the low signalto-noise ratio (SNR) regime, the LMMSE estimator reduces the mean squared error (MSE) by at least 6 dB; in the high SNR regime, the LMMSE estimator lowers the error floor on the MSE by 86.4%; 2) For the asynchronous OAC, our LMMSE and SP-MAP estimators are on an equal footing in terms of the MSE performance, and are significantly better than the ML estimator. On the other hand, in terms of the computational complexity, the SP-MAP estimator is much more efficient than the LMMSE estimator.

show abstract

Intersymbol interference resilient interleaving architecture for multi‐stream interleaved frequency division multiple access system

Kumar¹,

Stuwart

2022

Int J Communication

View full text Add to dashboard Cite

A multi-stream cyclic interleaving architecture for an interleaved frequency division multiple access (IFDMA) system is proposed. The proposed scheme exploits the full benefits of maximal length sequence (m-sequence), in contrast to single data stream transmission scheme proposed in earlier works, thereby allowing simultaneous transmission of multiple data streams by each user. The cyclic spreading allows the separation of multiple data streams for each user in addition to intersymbol interference (ISI) minimization. The assignment of orthogonal subcarriers to each user compensates multiuser interference (MUI). The increase in the number of data stream transmission improves the data rate of the system. The proposed scheme employs maximal ratio combining (MRC) to maximize the instantaneous signal-to-noise ratio (SNR) of the multipath signal. The performances of the proposed interleaving scheme are compared with the minimum mean square error frequency domain equalization (MMSE-FDE)-based conventional interleaving scheme. Despite the simultaneous transmission of multiple data streams, the proposed scheme retains the performance of single data stream transmission.

show abstract

Flexible Subcarrier Allocation for Interleaved Frequency Division Multiple Access

Cited by 19 publications

References 14 publications

New Transceiver Designs for Interleaved Frequency Division Multiple Access

New Transceiver Designs for Interleaved Frequency Division Multiple Access

Bayesian Over-The-Air Computation

Intersymbol interference resilient interleaving architecture for multi‐stream interleaved frequency division multiple access system

Contact Info

Product

Resources

About