This paper proposes a probabilistic amplitude shaping (PAS) scheme with systematic cascaded staircase and Hamming codes (CSHC). The integration of low-complexity concatenated codes within PAS and the use of the SIHO decoder are enabled by applying the inter-bit independence assumption. This ensures compatibility with high throughput transmission. In addition, the use of a reduced test pattern set in the SIHO decoder reduces the test pattern cardinality by 34.37%. The proposed scheme is experimentally demonstrated by self-homodyne coherent transmission over a 22.5 km 7-core fiber, with 21 wavelength division multiplexing (WDM) channels in the C-band is demonstrated. The total rate of the WDM-space division multiplexing (SDM) system is 21.77 Tbit/s. The experimental results show that the proposed PAS scheme with CSHC provides a gain of more than 8 dB in the back-to-back (BtB) scenario at the pre-FEC BER of 2.88E-2. Moreover, an average gain of 7.26 dB is achieved at the same threshold in WDM-SDM transmission.

Multi-sources Direction of Arrival (DOA) estimation based on Unmanned Aerial Vehicle (UAV) draws much attention for its flexibility and practicability. Meanwhile, the UAV collaborative technology can be used to guarantee the spatial Degree of Freedom (DOF), but it is always puzzled by the imprecise array structure and the strict demand of Radio Frequency (RF) chains calibration. The random amplitude and phase differences among the units deeply disturb the DOA estimation. To handle this random problem, a unique UAV network is designed, and a fourth-order cumulant-based multi-sources DOA estimation algorithm is proposed in this letter. The network consists of one main unit with two antennas and several assistant units with one antenna, the main unit provides the effective amplitude and phase information and the assistant units are used to ensure the spatial DOF. Therefore, both the array structure information and RF chain calibration of assistant units are not needed. The simulation results verify that the proposed algorithm is effective for multi-sources DOA estimation even with random amplitude and phase differences among the units.

Semantic segmentation, aiming to assign a categorical label to each pixel in an image, has drawn a lot of attention and has made significant achievements in recent years. However semantic segmentation remains a challenging problem caused by occlusion due to the lack of view information. In practice, the result of pixel assignment is greatly influenced by the scene information, especially in complex occlusion areas. One way to address the pixel assignment problem of occlusion areas is to train a feature representation that is extracted with enough scene information. To this end, we present light robust features(LRFs) through light field(LF), which contains all the light information of the scene. In addition, LRF consists of two components: 1)light color features(LCFs) and 2)light spatial features(LSFs). On the one hand, LCF is the expert in exploring the comprehensive RGB characteristic of LF images. When training LCF, we adopt a ResNet based feature extraction module. Moreover, a cross-entropy loss is deployed in LCF network. On the other hand, we design a LSF feature extraction module, which has a similar architecture to a robust depth estimation network. The difference between LCF and LSF is that LSF represents the depth characteristic of LF images. Finally, by combining LCF and LSF through pyramid-pooling and conditional random field(CRF) module, LRF can alleviate the influence of the occlusion, even in scenes of multi scales and complex categories. Experiments are conducted on the LF Semantic Segmentation data sets. We show that LRF produces competitive performance compared with state-of-the- art approaches.

Industrial IoT faces adversity in radio environment due to harsh physical condition and interference from co-located wireless systems. To mitigate these challenges, channel hopping is leveraged in a number of standards, including IEEE 802.15.4- 2015. The baseline version of the channel hopping described in this standard does not guarantee the best performance, especially in terms of network stability and latency. This paper illustrates the problem by means of a test-bed, and then proposes a channel blacklisting algorithm, which makes use of the channel quality statistics as they are stored in the Cloud. Claims of improvement are corroborated by the results obtained through simulation.

A demonstration of 6TiSCH Industrial IoT network handling network resource management and data collection and analytics.

Service diversity is expected in the upcoming fifth-generation (5G) cellular networks, which poses great challenges to the underlying waveforms to accommodate heterogeneous service requirements in a flexible way. By dividing the bandwidth into several subbands, each having a different numerology, this paper reports a field trial in time division duplex downlink conducted on a configurable test bed in a real-world environment for the performance evaluations of orthogonal frequency-division multiplexing (OFDM)-based 5G waveform candidates, i.e., cyclically prefixed OFDM (CP-OFDM), windowing OFDM (W-OFDM), and filtered OFDM (f-OFDM), in the presence of mixed numerologies. Field trial results confirm the feasibility of mixed numerologies and reveal the impact of several important system parameters, e.g., guard bandwidth, data bandwidth, signal-to-noise ratio (SNR), and transmit power. The results also suggest that f-OFDM outperforms CP-OFDM and W-OFDM in terms of both the spectrum efficiency and robustness in a high SNR regime, and the gain increases with a higher inter-numerology out-of-band interference. In some specific scenarios, ideal spectrum utilization can be realized by f-OFDM which completely removes the guard band.

The wavelength of synthetic aperture lidar (SAL) is very short; vibration of millimeter magnitude will significantly change the phase of echo signal and lead to the defocus of imaging in azimuth direction, so vibration estimation is a key step of SAL imaging. The existing Space Correlation Algorithm (SCA) used to estimate vibration of SAL is only suitable for the condition of narrow azimuth beam and high signal-noise ratio (SNR). Based on division of inner view field by two detectors along track, a new data obtaining model of SAL is established in this paper. Furthermore, a new vibration estimation method is proposed. Simulations validate that the vibration of SAL can be accurately estimated in the condition of wide azimuth beam and low SNR with the proposed method, meanwhile, good imaging result is obtained.

As the popularity of wireless communication increases rapidly, the unlicensed Industrial Scientific and Medical (ISM) band becomes crowded. Interference avoidance thus becomes an important issue when designing wireless communication in the unlicensed ISM band. As shown in related works, channel hopping with blacklisting is a promising mechanism addressing interference in 802.15.4e time slotted channel hopping (TSCH) networks. However, the blacklisting mechanism changes the number of channels used, and thus requiring the frequency hopping sequence (FHS) be regenerated. A time-random channel selection mechanism avoids regeneration overhead; however, it breaks close-to-optimality property of the default FHSs, which in turns leads to high probability of interference. In this paper, we propose a new algorithm that generates FHSs in presence of interference without regeneration overhead, and at the same time maintains the optimality property. With the new proposed mechanism, we can generate FHSs with one designed original sequence. Analysis and simulation results show that optimal/near optimal properties are achieved by these new FHSs.

This paper presents the design of a robust beamforming scheme for a two-way relay network, composed of one multi-antenna relay and two single-antenna terminals, with the consideration of channel estimation errors. Given the assumption that the channel estimation error is within a certain range, we aim to minimize the transmit power at the multi-antenna relay and guarantee that the signal to interference and noise ratios (SINRs) at the two terminals are larger than a predefined value. Such a robust beamforming matrix design problem is formulated as a non-convex optimization problem, which is then converted into a semi-definite programming (SDP) problem by the S-procedure and rank one relaxation. The robust beamforming matrix is then derived from a principle eigenvector based rank-one reconstruction algorithm. We further propose a hybrid approach based on the best-effort principle to improve the outage probability performance, which is defined as the probability that one of two resulting terminal SINRs is less than the predefined value. Simulation results are presented to show that the robust design leads to better outage performance than the traditional non-robust approaches.

Fairness is an important design criterion for medium access control protocol in multihop wireless networks. It is a complex problem due to its many dimensions that include consideration of location-dependent contention, spatial reuse of channels, and desire to achieve fully distributed scheduling in the wireless communication systems. This paper presents a localized and fully distributed algorithm with fair scheduling in multihop wireless networks. The proposed algorithm incorporates start time fair queuing (STFQ) into the distributed coordination function (DCF) in IEEE 802.11. Our algorithm accounts for the services that have already been received by the sender to adjust the backoff timer to ensure that every flow gets a fair service. We propose a simple data structure that every node (sender or receiver) needs to maintain and an update mechanism that achieves fairness. We illustrate through simulations that the proposed algorithm achieves the desired fairness.

Traditional CAD systems are also called single user CAD as single users exclusively operate these systems. This paper demonstrates a novel method that implements cooperative geometry editing between a number of users on traditional CAD systems. In the proposed implementation, a single user CAD, where participants run their own CAD processes in local computers or workstations, can simultaneously share and coedit a design model with other single users in different sites through a client server architecture. Information packages pertaining to the creation and modification of a shared CAD model is also broadcast among the participants. Because there is no need for frequent image upgrades, which in turn results in high latencies and a very disappointing interaction behavior, the amount of data that has to be manipulated in this proposed system is dramatically reduced. This is due to the fact that after an initial model download, only the changes of the model are transmitted.