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Traffic safety and efficiency are the most important motivations for the rapid development of vehicular ad hoc network (VANET) technology. VANET is considered to provide the unified platform and solutions for the intelligent transportation system (ITS). In this paper, a novel method named spectrum penetration is proposed to improve the throughput of multi-channel MAC for VANET. Meanwhile, it can overcome...
In mobile edge computing systems, mobile devices can offload compute-intensive tasks to a nearby \emph{cloudlet}, so as to save energy and extend battery life. Unlike a fully-fledged cloud, a cloudlet is a small-scale datacenter deployed at a wireless access point, and thus is highly constrained by both radio and compute resources. We show in this paper that separately optimizing the allocation of...
Massive MIMO systems, where base stations are equipped with hundreds of antennas, are an attractive way to handle the rapid growth of data traffic. As the number of users increases, the initial access and handover in contemporary networks will be flooded by user collisions. In this work, we propose a random access procedure that resolves collisions and also performs timing, channel, and power estimation...
In this paper, a novel impulsive noise (IN) cancel- lation scheme based on structured compressed sensing (SCS) for multiple input multiple output orthogonal frequency division multiplexing (MIMO-OFDM) power line communication systems is proposed. The SCS theory is introduced to IN recovery for the first time in this paper to the best of the authors' knowledge, and the gap of lack of research on the...
The combination of singular value decomposition (SVD)-based beamforming and filter bank multicarrier with offset quadrature amplitude modulation (FBMC/OQAM) has not been successful to date. The difficulty of this combination is that, the beamformers may change dramatically between adjacent subchannels, therefore destroy the orthogonality of FBMC/OQAM real-valued symbols, under frequency selective...
This paper studies a full-duplex filter-and-forward (FD-FF) relay system in frequency-selective channels. Conventionally, the loop-back signal at the FD relay is treated as harmful self- interference and needs to be significantly suppressed via both analog- and digital-domain cancellation. However, the performance of the conventional self-interference cancellation approach is fundamentally limited...
In practice, wireless nodes may have different mobility and/or different scattering environment leading to disparity in coherence time and/or coherence bandwidth. Coherence diversity, as a novel source of gain, exploits fading condition disparity of different nodes to provide gain. Downlink transmission for two wireless nodes is considered in three scenarios of fading conditions disparity: in coherence...
Due to their lack of assessment mechanisms of link quality in VANET environments, routing protocols do not deal efficiently with highly volatile links. One way to fill this gap would be to anticipate links breakages with new route computation. Currently available link quality indicators are not sufficiently responsive to consider forecasting. In this paper we present a novel predictive link quality...
This paper proposes a new paradigm of shared spectrum access between cellular wireless communications (CWC) and radio astronomy systems (RAS). Traditionally, most spectrum chunks are separately allocated to CWC and RAS, with a few shared spectrum without guaranteed spectrum access for RAS. Furthermore, RAS sites are generally set up at remote locations, protected by radio quiet zones. In view of growths...
New waveform candidates are being investigated for the fifth generation wireless systems. Among the promising candidates, generalized frequency division multiplexing (GFDM) offers the flexibility to address a wide range of requirements (e.g. low latency, coarse synchronization, etc.). Due to the non- orthogonality of GFDM, the transmit signal subjects to inter-symbol and inter-carrier interference...
This paper proposes a novel and simple orthogonal faster than Nyquist (OFTN) data transmission and detection approach for a single input multiple output (SIMO) system. It is assumed that the signal having a bandwidth is transmitted through a wireless channel having multipath components. Under this assumption, the current paper provides novel OFTN transmission and symbol-by-symbol detection approach...
Sparse channel estimation (SCE) in orthogonal frequency division multiplexing (OFDM) systems with large number of virtual sub-carriers and regularly spaced pilots is studied in this paper. Such OFDM systems are present in wireless standards like long term evolution (LTE). We numerically evaluate the performance of popular compressive sensing (CS) algorithms and shows that low complexity CS algorithms...
In this paper, we present an innovative back-channel wireless communication concept. The proposed back- channel communication enables ultra-low power (ULP) devices that are neither WiFi (IEEE 802.11a/g/n) nor Bluetooth Low Energy (BLE) compliant to receive messages from both WiFi and BLE transmitters. This allows communication between heterogeneous devices beyond the boundary of WiFi and BLE standards...
Visible light communications (VLC) technology has recently emerged as a complementary technology to the indoor radio frequency (RF) networks. While the backhauling of the indoor RF networks has been supported by fiber optics, the backhauling of the VLC network is still an open research problem. Power line communications (PLC) has been considered as a possible solution for the VLC networks due to its...
This paper reports an experimental investigation of using orthogonal frequency division multiplexing (OFDM) on orbital-angular momentum (OAM) channels when there is intersymbol interference (ISI) caused by multipath effects. The impulse response measurement indicates that due to the divergence of OAM beams, channels of larger OAM number are more affected by the ISI caused the reflections from surrounding...
This paper studies the physical-layer benefits of low latency operation in long-term evolution (LTE) networks. Latency reduction can be achieved by reducing the transmission time interval (TTI) from 1ms to the duration of only a few orthogonal frequency-division multiplexing symbols. The TTI shortening potentially enables faster link adaptation, thereby enhancing system performance. However, enabling...
In this paper, we investigate the coexistence problem between Wi-Fi and a pre-standard form of LTE over unlicensed bands, namely, LTE-Unlicensed (LTE-U). We address two coexistence problems. First, the different access mechanisms for Wi-Fi and LTE-U can lead to an increase in the collision rate and higher latency for both systems. We propose a modified Wi-Fi operation mode, whereby Wi-Fi stations...
Cloud radio access network (CRAN) is a promising candidate for the next-generation wireless communication systems. In CRAN, remote radio heads (RRHs) are deployed to serve users in a target area, which are connected to a central processor (CP) via limited-capacity links termed the fronthaul. In practice, the large amount of information transferred between each RRH and the CP for centralized processing...
A new FFT-based trellis receiver for multicarrier signals with nonorthogonal frequency spacing (spectrally efficient frequency division multiplexing, SEFDM) is proposed. It is based on FFT and max-log-MAP algorithm, which is adapted to work with frequency samples of received signal. The iterative version of demodulator is also developed. The performance of proposed iterative QPSK-SEFDM demodulation...
This paper investigates the energy efficient resource allocation for OFDM relay networks, where K users receive information via L helping relays. For such a system, an optimization problem is formulated to maximize the system energy efficiency (EE) by jointly optimizing the relay selection, subcarriers assignment and power allocation under the proportional rate constraints and available power constraint...
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