Multi-User Detection Based on Expectation Propagation for the Non-Coherent SIMO Multiple Access Channel

We propose a novel joint activity, channel and data estimation (JACDE) scheme for multiple-input multiple-output (MIMO) systems. The contribution aims to allow significant overhead reduction of MIMO systems by enabling grant-free access, while maintaining moderate throughput per user. To that end, we extend the conventional MIMO transmission framework so as to incorporate activity detection capability without resorting to spreading informative data symbols, in contrast with related work which typically relies on signal spreading. Our method leverages a Bayesian message passing scheme based on Gaussian approximation, which jointly performs active user detection (AUD), channel estimation (CE), and multi-user detection (MUD), incorporating also a well-structured low-coherence pilot design based on frame theory, which mitigates pilot contamination, and finally complemented with a detector empowered by bilinear message passing. The efficacy of the resulting JACDEbased grant-free access scheme in the cell-free MIMO system setup compliant with fifth generation (5G) new radio (NR) orthogonal frequency-division multiplexing (OFDM) signaling is demonstrated by simulation results. The results are shown to outperform the current state-of-the-art and approach the performance of an idealized (genie-aided) scheme in which user activity and channel coefficients are perfectly known.

Section: Discussionmentioning

confidence: 99%

Grant-Free Access via Bilinear Inference for Cell-Free MIMO With Low-Coherence Pilots

Iimori

Takahashi

Ishibashi

et al. 2021

“…Non-coherent signal recovery promises to reduce the access latency caused by the need to acquire explicit CSI before data decoding [8], [50]. This is specifically appealing for short packet communications such as in MTC.…”

Section: A Non-coherent Decoding Of Mtdsmentioning

confidence: 99%

Joint Coherent and Non-Coherent Detection and Decoding Techniques for Heterogeneous Networks

Marata

López

Djelouat

et al. 2023

Cellular networks that are traditionally designed for human-type communication (HTC) have the potential to provide cost effective connectivity to machine-type communication (MTC). However, MTC is characterized by unprecedented traffic in cellular networks, thus posing a challenge to its successful incorporation. In this work, we propose a unified framework for amicable coexistence of MTC and HTC. We consider a heterogeneous network where machine-type devices coexist with enhanced mobile broadband (eMBB) devices and propose transceiver techniques that promote efficient signal recovery from these devices. For this, we present an eMBB pilot and MTC data generation strategy that facilitates joint coherent decoding of eMBB data and non-coherent decoding of MTC data. Furthermore, we assess the feasibility of coexistence using receiver operating characteristics, outage probability, and normalized mean square error (NMSE). Our numerical results reveal that a harmonious coexistence of the heterogeneous services can be achieved with properly configured average signal-to-noise ratios and pilot length.

“…Taking into account the focus on scalability, which at the receiver side translates to controlling complexity, two suitable candidate methods to be applied for OS-QSM demodulation are the generalized approximate message-passing (GAMP) algorithm [44]- [46], and the iterative shrinkage thresholding algorithm (ISTA) [35], [36], both of which possess quadratic complexity on the size 2T n T of the signal vector u. It is wellknown, however, that the GAMP algorithm relies on the particular structure of measurement matrix and the independence of the received signal, which in the case of QSM cannot be generally assumed, as a direct consequence of the utilization of STBCs in the dispersion matrices.…”

Section: A Sparse Formulation Of Qsm Receiversmentioning

confidence: 99%

Scalable Quadrature Spatial Modulation

Rou

Abreu

Iimori

et al. 2022

We consider quadrature spatial modulation (QSM) schemes, which achieve high spectral efficiency (SE) via the dispersion of a relatively small number P of M -ary modulated symbols over a large number of combinations of nT transmit antennas and T transmit instances. In particular, we design a new space-time block code (STBC)-based scalable QSM scheme combining high SE with maximum diversity and optimum coding gains. Deriving a closed-form expression for the optimum SE, we show that scaling the size T with nT not only is required to achieve SE optimality, but also results in further gains in bit error rate (BER) performance. Building on the latter optimal parameterization, a fully optimized scalable QSM (OS-QSM) transmitter design is then obtained by introducing a new dispersion matrix index selection algorithm that ensures even utilization of spatial-temporal resources. Finally, a new greedy boxed iterative shrinkage thresholding algorithm (GB-ISTA) QSM receiver is proposed, which exploits the inherent sparsity of QSM signals and while detecting spatially and digitally modulated bits in a greedy fashion. The resulting low complexity of the new receiver, which is linear on nT , enables the utilization of OS-QSM in systems of previously prohibitive dimensions.