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A non-orthogonal multicarrier signal, termed spectrally efficient frequency division multiplexing (SEFDM), is investigated in this work. It improves spectral efficiency by compressing sub-carrier spacing below the symbol rate at the cost of self-created inter carrier interference (ICI). Sphere decoding (SD) is an efficient method to recover signals approaching maximum likelihood (ML) performance....
This paper presents a recursive oblique projector using the Gram-Schmidt process. The recursive construction of oblique projectors allows a receiver to prevail interference and noise environment in direct-sequence code-division multiple-access (DS/CDMA) system. When the number of the interfering users in the system increases or decreases, the oblique projector is recursively updated by the proposed...
This paper presents pilot symbol aided channel estimation in Filter Bank Multicarrier (FBMC). FBMC has been employed widespread in communication applications because of its good spectral behaviors. Unlike Orthogonal Frequency Division Multiplexing, FBMC structure avoids imaginary interference. So that auxiliary symbols are employed and decrease peak to power ratio and improve achievable capacity....
Although the base station processing and the majority of the protocols of the wireless systems are standardized by 3GPP, the receiver architecture and implementation remain vendor-dependent. The receiver design should fulfill computational efficiency requirements, and be evaluated in practical simulators or emulators that are compliant with real-world wireless standards. In this paper, we provide...
In discrete multitone (DMT) modulation systems, the channel duration can be longer than the cyclic prefix, yielding both inter-block and inter-carrier interference. In order to avoid these effects, time-domain equalization (TEQ) techniques are usually employed before DMT demodulation. This letter introduces a modification of the iterative minimum delay spread (MDS) method proposed by Lopez-Valcarce...
The emerging 5G mobile communication standard aims to increase the throughput and, in the same time, to considerably increase the number of users serviced concurrently (Internet of Things). The key direction for achieving these requirements is to heavily extend the use of the spatial degrees of freedom, especially in the multi-user scenarios. Multi-User Massive MIMO (MU-MIMO) is one of the key technologies...
In this work, we propose a beam selection scheme that exploits the geometric sparsity of the multi-user (MU) massive multiple input and multiple output (MIMO) channel, using its beamspace representation. Assuming knowledge of the beamspace channel, the beamspace precoder consists in selecting and weighting the beams steered to the users, in order to maximize the signal-to-interference-and-noise ratio...
Noncoherent multi-user detection schemes in combination with subspace projection were shown to be an attractive approach in multi-user massive MIMO systems. Up to now, the subspace projection has been performed via a singular value decomposition (SVD) of the receive matrix and nulling the non-signal dimensions. In this paper, we employ an alternative approach to the subspace estimation step, namely...
In the ultra dense network (UDN), user-centric virtual cell (VC) has been proposed to weaken the traditional concept of base station centric cell, where each user is served by several transmit points (TPs). The overlapped VCs in UDN will result in severe inter-VC interference and degrade the system throughput. Merging overlapped VCs can transform the serious inter-VC interference into intra-VC interference,...
This paper presents a low-complexity two-dimensional (2D) detection strategy for shingled magnetic recording (SMR) media. The detection strategy involves the use of multi-level 2D BCJR detector along-track for inter-symbol interference (ISI) cancellation and regular BCJR detector across tracks for inter-track interference (ITI) cancellation. This is applied in a multi-track two dimensional magnetic...
OFDM suffers from high spectrum sidelobes and lacks the ability to support an important feature of 5G and future wireless communications: flexible numerology. To overcome these shortcomings, we consider in this paper filtered OFDM (F-OFDM) as a candidate solution, which is able to provide greater flexibility and adaptability than traditional CP-OFDM. We propose filters constructed by filter banks...
Using OMP algorithm for time-delay detecting and apply BEM based on comb-type pilot for channel estimation is the most commonly used method for sparse time-frequency doubly-selective channels, but the channel estimation performance will decrease sharply when the number of channel paths is large, and this method need to obtain the channel sparsity as prior information in advance. In this paper, a novel...
In this paper, we jointly perform the cell selection and activation (CSA) to maximize the network energy efficiency (EE) under users' long-term rate constraints for green communications in ultra-dense heterogeneous networks (UD-HetNets). The finally formulated problem is in a mixed-integer fractional form and hard to tackle. We first transform it into a parametric subtractive form, by which we reach...
Automotive industry will be greatly benefited by the advent of 5G Networking and the huge boost in performance and coverage it will support. Road safety and traffic efficiency services will be significantly upgraded through seamlessly interconnected devices, while latency decrease will most likely allow autonomous driving to become a commodity, available to everyone. This technology will have a huge...
In this work, we study a practical resource allocation (RA) scheme that considers heterogeneous services in OFDMA femtocell networks. Heterogeneous services include guarantees of the minimum data-rate for delay-sensitive (DS) users and the fairness for delay-tolerant (DT) users. The RA problem is formulated to maximize the total throughput of all femtocells while satisfying the constraints of cross-tier...
We consider the problem of minimizing the total transmission power for a OFDM network where mutual interference exists among cells, with the power and load constraints for each base station (BS) and the rate demand constraint for every user. To solve the power minimization problem, we develop a distributed resource allocation and power control algorithm with low complexity. The complexity of the proposed...
The adjacent cell interference (ACI) issue faced when applying multiple user superposition transmission (MUST) scheme to uplink transmission in cellular networks is considered in this article. To dealing with ACI we proposed a novel MUST scheme called interference fusion multiple access (IFMA). In our scheme transmission rate of superimposed ACI is reduced via compute-and-forward framework. As a result...
This paper aims to evaluate the system level performance of the newly proposed non-orthogonal multiple access scheme sparse code multiple access (SCMA) with uplink grant-free transmissions for 5G massive machine-type communication (mMTC) scenario. The challenge lies in the modeling and abstraction of physical layer actions as the link-to-system interface, including the features of overloading, grant-free...
The compressive sensing-based random access may get impacted largely by other cell interference (OCI), which may shatter the sparsity of the received signal model unless the signature space assignment among interfering cells is carefully handled. In this paper, we investigate the performance of multi-sequence spreading-based random access (MSRA) scheme under multi-cell environment. In particular,...
Massive Machine Type Communication (mMTC) is one key usage scenario in future 5G. To fulfill the massive connection requirement in mMTC, and reduce the signaling overhead, a novel grant free Random Non-Orthogonal Multiple Access (RNOMA) scheme is proposed in this paper, inspired by the concept of conventional NOMA. In RNOMA, one physical resource area is reserved and divided into orthogonal resource...
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