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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....
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...
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...
Maximum-likelihood (ML) receivers are optimum receivers for MIMO systems, but their complexity grows exponentially with the modulation order of the codeword and the number of spatial layers. The Reduced Complexity ML (R-ML) receivers based on low complexity adaptation of the max-log MAP detector and reduction of searching space are a good compromise to satisfy complexity-performance trade-off. In...
We consider the performance of a low complexity Vertical Bell Laboratories Layered Space Time system with a maximum ratio combining receiver (LC-VBLAST) in an uplink massive multiple-input-multiple-output (MIMO) deployment with single antenna users. This receiver is known to give a similar error rate performance to zero forcing (ZF) for simple systems while reducing complexity. In this paper, we show...
We propose a differential encoding scheme and several differential decoding schemes for asynchronous multiuser MIMO systems based on orthogonal space-time block codes (OSTBCs) where neither the transmitters nor the receiver has knowledge of the channel. We derive novel low complexity differential decoders by performing interference cancelation in time and employing different decoding methods. The...
Spectrally Efficient Frequency Division Multiplexing (SEFDM) is a non-orthogonal multi-carrier communication technique that can pack more sub-carriers than Orthogonal Frequency Division Multiplexing (OFDM) for a given bandwidth. In this paper, we propose a hybrid soft Iterative Detection (ID) together with Fixed Sphere Decoding (FSD) for QAM modulation schemes from 4QAM to 16QAM. In terms of 4QAM,...
It is widely accepted that SC-FDE (Single Carrier with Frequency Domain Equalization) schemes are preferable for the uplink of broadband wireless systems since these signals have lower PAPR (Peak to Average Power Ratio) than OFDM (Orthogonal Frequency Division Multiplexing) signals. However, when we want to employ power-efficient grossly nonlinear amplifiers, as in satellite communications, the SC...
Research on fifth generation (5G) radio access technology (RAT) is ramping up, with the goal of significantly improving user data rates and latency compared to previous RAT generations. While energy efficiency (EE) of the user equipment (UE) was not a key optimization parameter for the current wireless standards, it is anticipated to become a distinguishing factor for 5G. In this paper, we analyze...
Future wireless communications should be designed efficiently to support multi-mode operations for different types of applications, such as machine-to-machine, video streaming, web browsing and voice. In the physical layer multi-mode operation could include the coexistence of single carrier and multicarrier modulations. To reduce overall complexity and power consumption, it is highly desirable to...
In this paper, chirp spread spectrum (CSS) based modulation schemes for capsule endoscopy applications are proposed. The On-Off-Keying (OOK) technique has been conventionally used for the capsule endoscopy applications, but it is known to be susceptible to narrow-band interference such as TV signals. In order to enhance robustness to interferences, we propose two CSS based modulation schemes which...
This paper is concerned with a simplified hard decision feedback equalizer (S-HDFE) for single carrier modulation with cyclic prefix. In this paper, we focus on the coded system in which the feedback symbols are reproduced from hard decisions of channel decoding results. Cholesky decomposition is the key technique for simplifying the feedback filter calculation of S-HDFE. With the same matched filter...
In this paper we study the performance and complexity tradeoff of filtered multitone modulation (FMT) in statistically representative indoor radio channels. We consider two design approaches. The first one is based on the use of long prototype pulses with high sub-channel frequency confinement. The second one follows an orthogonal design with minimal length pulses (down to the length of one transmitted...
In this paper, the performance of an ultra-wideband (UWB) communication system employing orthogonal pulse position modulation (PPM) and non-orthogonal pulse position modulation (NPPM) is considered. Time hopping (TH) is used to decrease the effect of multiuser interference. It is shown that for a large number of users, NPPM provides better bit error rate (BER) performance than PPM. We also determine...
Future wireless communication systems being characterized by tight frequency reuse, adaptive modulation and coding schemes and diversified data services will be interference limited by the interfering signals of diverse rates and strengths. Frequency reuse factor of 1 being proposed for the next generation mobile systems will lead to 1 or 2 dominant interferers. We propose in this paper a low complexity...
We propose resource allocation algorithms based on the auction method for uplink OFDMA cellular networks. We consider cellular systems that employ the traditional static frequency reuse as well as the next-generation systems that aim to achieve a universal frequency reuse via base-station coordination. Our algorithms are designed for finite input alphabets and also account for non-ideal practical...
In this paper, we study the iterative detection problem for a coded system with multi-ary modulation. We show that, with iterative linear minimum-mean-square-error (LMMSE) detection, superposition coded modulation (SCM) can provide performance superior to that with other traditional signaling schemes used in trellis coded modulation (TCM) and bit-interleaved coded modulation (BICM). This finding provides...
Due to small sideband power leakage, filter bank multicarrier techniques are considered as interesting alternatives to traditional OFDMs for spectrum pooling cognitive radio. In this paper, we propose an oversampled filter bank multicarrier system for cognitive radio. The increased spacing between adjacent subcarriers in the oversampled filter bank multicarrier system largely reduce the intercarrier...
In this paper, an energy efficient adaptive modulation scheme is proposed for a wireless cognitive radio ad hoc network, where each node is equipped with cognitive radio and the network is an OFDMA system operating on time slots. In each slot, the users with new traffic demand will sense the spectrum and locate the available subcarrier set. Then they choose subcarriers with favorable channel condition...
Spectrum sensing in the context of wireless microphone (WM) signals is considered in this paper. The spectrum sensing algorithm developed in this study makes use of the property that the bandwidth of the WM signal is narrow compared with the bandwidth of a digital television (DTV) channel. As a result, the power of the WM signal is highly concentrated in the frequency domain and there are apparent...
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