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Space–time (ST) coding combined with orthogonal frequency-division multiplexing (OFDM) is a robust transmission system. However, ST-OFDM system performance may degrade because of the intercarrier interference (ICI) in frequency-selective fading channels. To mitigate the ICI, a parallel cancelation (PC) algorithm is employed and combined with a 2 $\times$ 1 ST code to form an STPC-OFDM system. Further...
In this paper, we propose a tracking mechanism for the residual sampling clocking offset (SCO) with corresponding pilot and auxiliary pilot arrangements for filter bank multi-carrier (FBMC) offset QAM (OQAM) baseband receiver in the 60 GHz band. This work can effectively compensate the non-ideal effects on the high-band subcarriers while using more data subcarrier for increasing bandwidth efficiency...
LoRa™ is low power wide area wireless network (LPWAN) protocol for Internet of Things (IoTs) applications. LPWAN has been enabling technology of large scale wireless sensor networks (WSNs). Effective cost, long range and energy efficiency of LPWANs make them most suitable candidates for smart city applications. These technologies offer novel communication paradigm to address discrete IoT's applications...
This paper presents a 1024-QAM OFDM signal capable WLAN receiver in 65 nm CMOS technology. Thermal noise-based IQ frequency-independent mismatch correction and IQ frequency-dependent mismatch correction with baseband loopback are proposed for the self-calibration in the receiver. By using proposed calibration method, neither received external signal nor RF loopback are necessary and the residual IQ...
IEEE 802.11n/ac wireless local area network (WLAN) supports frame aggregation, called aggregate medium access control (MAC) protocol data unit (A-MPDU), to enhance MAC efficiency by reducing protocol overhead. However, the current channel estimation process conducted only once during the preamble reception is known to be insufficient to ensure robust delivery of long A-MPDU frames in mobile environments...
This paper presents novel techniques to achieve high-rate ultrasonic communications through thick metallic barriers utilizing ultrasound and provides a characterization and analysis of a 7 × 7 MIMO-OFDM acoustic-electric channel array and determines that, due to unique channel properties yielding well-conditioned channel gain matrices, a slowly adaptive crosstalk mitigation structure achieves near-optimal...
Visible light communication (VLC), as a promising alternative to the next generation wireless communication technologies, has drawn extensive research interests. In this paper, a novel hybrid intensity modulated direct detection (IM/DD) communication system is proposed, which integrates the multi-carrier and single-carrier modulation to enhance spectrum efficiency and support different qualities of...
This work presents a novel method we call: Frequency Injection Interfacing (FII), for OFDM communication systems. With FII, an external system or observer can communicate to an OFDM receiver through a frequency encoder that injects additional frequency content into the received signal. Specifically, the null subcarriers at the edges of the OFDM waveform are turned on or off to represent a binary code...
This paper explores new multicarrier signals and systems for 5G; spectrally efficient frequency division multiplexing (SEFDM), in which higher spectral efficiency (SE) compared to conventional orthogonal frequency division multiplexing (OFDM) is achieved by violating the orthogonality of its subcarriers. This work proposes new system and receiver models and then investigates the employment of various...
The existing solutions for multi-user detection in uplink (UL) grant-free sparse code multiple access (SCMA) rely on the prior knowledge of user sparsity, i.e., the number of active users. An alternative solution, which sets the sparsity as a statistically empirical value to get a rough active user set and then eliminates the false detected inactive users with joint message passing algorithm (JMPA),...
This paper considers a K-user single-input-single-output interference channel with inter-symbol interference (ISI), in which the channel coefficients are assumed to be linear time-invariant with finite-length impulse response. The primary finding of this paper is that, with no channel state information at a transmitter (CSIT), the sum-spectral efficiency can be made to scale linearly with K, provided...
Pilot spoofing attack is a serious threat to timedivision duplex (TDD) orthogonal frequency division multiplexing (TDD-OFDM) system. By employing identical pilot tones as a legitimate receiver, an adversary can contaminate the uplink channel estimation between a transceiver pair. To solve this problem, we in this paper propose an independent component analysis (ICA) based channel estimation and identification...
The forthcoming fifth generation of mobile technology (5G) will be designed to satisfy the demands of 2020 and beyond. 5G does not just promise a huge increase in terms of data rates and capacity but it also targets new kind of use cases like Internet of Things or vehicular communications. The currently deployed 4G technology does not provide enough network capabilities to support this wide diversity...
This paper proposes a new physical layer security scheme for multiuser multiple-input multiple-output (MIMO) systems under the presence of a passive eavesdropper. In the proposed scheme, the base station (BS) assumes a nonexistent receiver and its corresponding channel responses arbitrarily. Such a receiver and channels are called the imaginary receiver and the imaginary channels in this paper, respectively...
Recent work has proposed the integer-forcing (IF) linear receiver architecture as a promising alternative to the joint maximum likelihood (ML) receiver. It has been proven that the IF linear receiver can operate very close to the (optimal) performance of the joint ML receiver, but with essentially the same implementation complexity as a zero-forcing (ZF) linear receiver. In this paper, we take the...
Time-interleaved analog-to-digital converters (TIADCs) have recently been suggested for multi-Gigabit systems because of their high sampling rate. In practice, a major bottleneck of using a TI-ADC is mismatch occurring between individual sub-ADCs. In this paper, we derive an approximate bit error rate (BER) expression for high-speed pulse amplitude modulated (PAM) and quadrature amplitude modulated...
Growth in telecommunication world leads to an increase in the importance of efficient usage of frequency spectrum. Increasing number of subscribers and their demands force network operators to use the frequency bands as efficiently as possible. It is necessary to detect and prevent the interference of secondary or unauthorized frequency band occupations. Cyclostationary signal analysis is widely used...
Channel estimation techniques are crucial for reliable communications. This paper is concerned with channel estimation in a filter bank multicarrier spread spectrum (FBMC-SS) system. We explore two channel estimator options: (i) a method that makes use of a periodic preamble and mimics the channel estimation techniques that are widely used in OFDM-based systems; and (ii) a method that stays within...
5G will have to cope with a high degree of heterogeneity in terms of services and requirements. Among these latter, flexible and efficient use of all available non-contiguous spectrums for different network deployment scenarios is one challenge for the future 5G. To maximize spectrum efficiency, the 5G air interface technology will also need to be flexible and capable of mapping various services to...
Vehicle Ad Hoc Networks (VANETs) in Cooperative Intelligent Transport Systems (C-ITS) are based on the exchanges of messages among ITS-Stations (e.g., vehicles and roadside infrastructure) using the wireless G5 Dedicated Short Rate Communication (DSRC) standard to support safety-critical applications. VANETs require the authentication of ITS-stations and messages but the privacy of the drivers of...
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