In conventional preamble based channel estimation in OFDM/offset QAM (OFDM/OQAM) system, both the even index subcarriers and the odd index subcarriers are with identical value selected from { 1 } respectively to avoid inter-carrier interference (ICI), if and only if channel frequency response in neighbor few subcarriers remain invariable. However, it requires larger coherent bandwidth. In this paper, we propose an effective preamble design with ICI cancellation for channel estimation in OFDM/OQAM system. With this structure, we only utilize even (or odd) index of subcarriers as reference signal to avoid ICI, and then the channel information of remaining subcarriers can be estimated by the interpolation approach. Based on the sampling theorem, the mean square error (MSE) performance of the proposed preamble design is analyzed, where channel estimation performance is same for all subcarriers. Simulation and analytical results demonstrate that the proposed preamble design with ICI cancellation method outperforms the conventional one in term of channel estimation accuracy in OFDM/OQAM system.

As an effective method, exponential discriminant analysis (EDA) has been proposed and widely used to solve the so-called small-sample-size (SSS) problem. In this paper, a simple and effective generalization of EDA is presented and named as GEDA. In GEDA, a general exponential function, where the base of exponential function is larger than the Euler number, is used. Due to the property of general exponential function, the distance between samples belonging to different classes is larger than that of EDA, and then the discrimination property is largely emphasized. The experiment results on the Extended Yale and CMU-PIE face databases show that, GEDA gets more advantageous recognition performance compared to EDA.

This article focuses on improving the BiSeNet v2 bilateral branch image segmentation network structure, enhancing its learning ability for spatial details and overall image segmentation accuracy. A modified network called “BiconvNet” is proposed. Firstly, to extract shallow spatial details more effectively, a parallel concatenated strip and dilated (PCSD) convolution module is proposed and used to extract local features and surrounding contextual features in the detail branch. Continuing on, the semantic branch is reconstructed using the lightweight capability of depth separable convolution and high performance of ConvNet, in order to enable more efficient learning of deep advanced semantic features. Finally, fine-tuning is performed on the bilateral guidance aggregation layer of BiSeNet v2, enabling better fusion of the feature maps output by the detail branch and semantic branch. The experimental part discusses the contribution of stripe convolution and different sizes of empty convolution to image segmentation accuracy, and compares them with common convolutions such as Conv2d convolution, CG convolution and CCA convolution. The experiment proves that the PCSD convolution module proposed in this paper has the highest segmentation accuracy in all categories of the Cityscapes dataset compared with common convolutions. BiConvNet achieved a 9.39% accuracy improvement over the BiSeNet v2 network, with only a slight increase of 1.18M in model parameters. A mIoU accuracy of 68.75% was achieved on the validation set. Furthermore, through comparative experiments with commonly used autonomous driving image segmentation algorithms in recent years, BiConvNet demonstrates strong competitive advantages in segmentation accuracy on the Cityscapes and BDD100K datasets.

Infostations serve a demand for multimedia services with high quality and high data rate. The challenge for Infostation system design is how to download as many information bits when a mobile user drives through an Infostation cell. A variable rate TDMA/TDD radio architecture is chosen for study and experimental implementation because of its flexibility in a multi-user environment. A symbol rate and rate compatible punctured convolutional code controlled adaptive transmission scheme is proposed for the Infostation radio design. Data throughput is analyzed for a mobile user passing through an Infostation cell. The analysis indicates that three data rates at 0.25, 1.0 and 2.0 Mbps achieve greater than 85% of the theoretical throughput while simplifying the implementation. The punctured convolutional code is studied to maximize the Infostation throughput. A recommendation is made to use rate 1/2 coding scheme. An efficient rate adaptation algorithm is proposed and it can track the Rayleigh fading channel well and the capacity loss is negligible in various conditions.

We have developed an IP-over-Ethernet-based ultra high-speed multimedia wireless LAN prototype operating in the 60-GHz band. It employs a media-access-control (MAC) protocol based on reservation-based slotted idle signal multiple access (RS-ISMA), which was implemented in the former prototype, for supporting various IP traffic such as real-time AV traffic and best-effort web traffic. The protocol also has a new function called NACK sensing for the efficient retransmission of wireless multicast packets. It was demonstrated that the prototype can provide the world's fastest radio transmission speed of 128 Mbps for two-way communications. We have measured the throughput and latency of the prototype LAN for Ethernet-frame transmission in a point-to-point baseband-connected environment. The measurement showed that the prototype LAN provides a maximum throughput of 30 Mbps, and that the measured throughput agrees with the theoretically predicted throughput. It also showed that the maximum latency, which includes switching and routing latency in the wired part, is below 1 msec.

In our preceding paper, I-ISMA (Idle Signal Multiple Access for Integrated services), a combination of ISMA and time reservation technique, was proposed to transmit an integrated voice and data traffic in third generation wireless communication networks. There, the channel capacity of I-ISMA was evaluated by the static analysis. To fully estimate performance of contention-based channel access protocols, however, we also need dynamic analysis to evaluate stability, delay, etc. Particularly, in systems concerning real-time voice transmission, delay is one of the most important performance measures. A six-mode model to describe an I-ISMA system is set up. With some assumptions for simplification, the dynamic behavior of the system is approximated by a Markov process so that the EPA (Equilibrium Point Analysis), a fluid approximation method, can be applied to the analysis. Then, numerical and simulation results are obtained for some examples. By means of the same analysis method and under the same conditions, the performance of PRMA is evaluated and compared briefly with that of I-ISMA.

Developments in new frequency bands for wireless communications make a broadband channel for new services possible. Great effort has been made researching and developing broadband wireless communication in the 60-GHz millimeter-wave band since the early 1990s. In this paper, we design an ATM (asynchronous transfer mode)-based indoor millimeter-wave wireless local area network (WLAN) that supports multimedia transmissions and focus on the wireless access topic for implementation of wireless ATM. We propose an integrated multimedia transmission protocol, based on the MAC (medium access control) protocol, called RS-ISMA (reservation-based slotted idle signal multiple access). It supports CBR (constant bit rate), VBR (variable bit rate), ABR (available bit rate) and UBR (unspecified bit rate) transmissions and provides QoS (quality of service)-dependent adaptive retransmissions. An RS-ISMA-based prototype full-duplex indoor high-speed WLAN in the 60-GHz band was developed.

The Infostation concept has been proposed to provide convenient and cost effective access to high-speed mobile data services. An efficient IP packet transmission protocol is required to compensate for the high error rate inherent to fading radio channels. In this paper, a novel link layer retransmission scheme is proposed. Using the channel state and fading state estimators, the scheme adjusts the retransmission parameters dynamically in order to achieve the optimum performance under time-varying channel conditions. A theoretical analysis is presented for the case of a random error channel. Furthermore, a simulation tool is developed for evaluating the performance of the scheme in a fading channel with various parameters. The analysis and simulation results show that this new retransmission scheme can provide substantial improvement over traditional schemes. It gives a robust performance in both slow and fast fading conditions. In addition, the algorithm's sensitivity to parameter values and channel characteristics, such as Doppler frequency and fading statistics, is investigated. A unique attribute of this algorithm and performance analysis is that throughput is evaluated in IP packets rather than in physical layer packets.

This paper deals with the method of integration of voice and data in wireless communication systems. By applying the DSV (Data Steal into Voice) technique to D-TDMA (Dynamic Time Division Multiple Access) systems, this paper presents an MAC (Media Access Control) method of integration of voice and data for the systems such as cellular radios and cordless phones. After a brief review of the D-TDMA scheme and the DSV technique, the protocol called D-TDMA/DSV is described. Then, a static analysis to derive the channel capacity and a dynamic analysis to evaluate the throughput and delay performance are presented. An extension of TFA (Transient Fluid Approximation) analysis is employed in the dynamic analysis. With the same system parameters, the capacity of D-TDMA/DSV is compared with that of the traditional D-TDMA. Under the limitation of the blocking probability required for cellular radios, some numerical examples of dynamic analysis are given to show the throughput and delay performance of the system.

Corresponding to the development of B-ISDN, integrated services for data, voice, etc. are imperatively required for the so called third generation wireless communication networks. In this paper, I-ISMA (Idle Signal Multiple Access for Integrated services) is proposed to transmit integrated voice and data traffic from dispersed terminals to a base station. In the system, data packets and the first packets of talkspurts of conversational speeches are transmitted using ISMA protocol over a shared channel while subsequent packets of talkspurts are sent with time reservation technique. The channel capacity of I-ISMA is evaluated and compared with that of PRMA. The region in which I-ISMA has larger capacity than PRMA is figured out. Generally speaking, I-ISMA has larger capacity than PRMA when the duration for transmitting and detecting an idle signal is not too long and the channel is not too congested by the reserved voice transmissions. When we concern real time voice transmission, delay is one of the most important performance measures. Only is a qualitative discussion on delay performance given here. The quantitative evaluation is obtained by the dynamic analysis in our succeeding paper.

A millimeter-wave radio access system has a number of features that makes it appealing as one approach to broadband communications. However, for a millimeter-wave system to come into wide use, it must be miniaturized and the associated costs reduced. We have succeeded in realizing a compact 156 Mbps radio transceiver with a 38 GHz band optimizing RF architecture. We also adopted newly developed three-dimensional laminated MCMs using low cost plastic composite materials. It was confirmed in the initial experiments that this millimeter-wave wireless LAN equipment can cover a sufficient service area for broadband telecommunications in an indoor environment.

In this paper we analyze the characteristics of tapered multimode interference (MMI)-based coherent lightwave combiners, and theoretically confirm that the stable and clear multimode interference images exist in the tapered MMI combiners. We present the output characteristics of 21 tapered MMI-based coherent lightwave combiners under various structures, which are useful to optimally design the combiners. In order to extend the combiner to a multi-port (N1, N > 2) configuration, a new structure with the border shapes of two tangent arcs is proposed, by which we show an output power imbalance of about 0.5 dB between different input ports of an 81 tapered coherent lightwave combiner. Due to the advantages of no end-facet reflection, easy extension to a multi-port configuration, high tolerance for fabrication errors and a compact size, the tapered MMI structure is a good candidate as a coherent lightwave combiner used in large-scale photonic integrated circuits.

This paper proposes the use, in integrated wireless systems, of the Reserved Idle Signal Multiple Access with Collision Resolution (R-ISMA/CR) protocol for applications in future multimedia mobile communications. It is applied to the integrated voice and data wireless system. Moreover, the consideration is made of the integrated voice and the low-bit video wireless system in R-ISMA/CR. To integrate video we employed not only a packed discard for video packets when the video packet delay is more than a threshold value, but also the connection packet (CP) technique for improving the channel utilization. Finally the integration of voice, data, and low-bit-video wireless system in R-ISMA/CR is considered. The performance are evaluated mainly by simulations.

Clustering is known to be an effective means of reducing energy dissipation and prolonging network lifetime in wireless sensor networks (WSNs). Recently, game theory has been used to search for optimal solutions to clustering problems. The residual energy of each node is vital to balance a WSN, but was not used in the previous game-theory-based studies when calculating the final probability of being a cluster head. Furthermore, the node payoffs have also not been expressed in terms of energy consumption. To address these issues, the final probability of being a cluster head is determined by both the equilibrium probability in a game and a node residual energy-dependent exponential function. In the process of computing the equilibrium probability, new payoff definitions related to energy consumption are adopted. In order to further reduce the energy consumption, an assistant method is proposed, in which the candidate nodes with the most residual energy in the close point pairs completely covered by other neighboring sensors are firstly selected and then transmit same sensing data to the corresponding cluster heads. In this paper, we propose an efficient energy-aware clustering protocol based on game theory for WSNs. Although only game-based method can perform well in this paper, the protocol of the cooperation with both two methods exceeds previous by a big margin in terms of network lifetime in a series of experiments.

Traffic classification has recently gained much attention in both academic and industrial research communities. Many machine learning methods have been proposed to tackle this problem and have shown good results. However, when applied to traffic with out-of-sequence packets, the accuracy of existing machine learning approaches decreases dramatically. We observe the main reason is that the out-of-sequence packets change the spatial representation of feature vectors, which means the property of linear mapping relation among features used in machine learning approaches cannot hold any more. To address this problem, this paper proposes an Improved Dynamic Time Warping (IDTW) method, which can align two feature vectors using non-linear alignment. Experimental results on two real traces show that IDTW achieves better classification accuracy in out-of-sequence traffic classification, in comparison to existing machine learning approaches.

Neighborhood preserving embedding is a widely used manifold reduced dimensionality technique. But NPE has to encounter two problems. One problem is that it suffers from the small-sample-size (SSS) problem. Another is that the performance of NPE is seriously sensitive to the neighborhood size k. To overcome the two problems, an exponential neighborhood preserving embedding (ENPE) is proposed in this paper. The main idea of ENPE is that the matrix exponential is introduced to NPE, then the SSS problem is avoided and low sensitivity to the neighborhood size k is gotten. The experiments are conducted on ORL, Georgia Tech and AR face database. The results show that, ENPE shows advantageous performance over other unsupervised methods, such as PCA, LPP, ELPP and NPE. Another is that ENPE is much less sensitive to the neighborhood parameter k contrasted with the unsupervised manifold learning methods LPP, ELPP and NPE.

In this paper, we propose a modified R-ISMA (reserved idle signal multiple access) protocol for a wireless local area network (WLAN) with a hybrid system construction. The protocol can support a basic service area as large as that supported by a centralized system and allows the direct transmission between neighbor stations as in a distributed system without the problem of hidden terminals. Since a polling scheme is used during transmission of information packets, an ARQ (auto repeat request) scheme is easily applied. A dynamic analysis using transient fluid approximation analysys is used for performance evaluation. In the analysis, we use Fritchman channel model to describe a burst error environment. Some numerical examples using a set of practical system parameters are given. It is shown that the system performance is improved compared with a centralized system with R-ISMA.

In this paper, we propose DSVMA (Data Steal into Voice Multiple Access) scheme for integration of voice and data in wireless information networks. By using speech activity detectors and effective downstream control signals, DSVMA enables data terminals to transmit multi-packet messages when voice terminals are in silent periods. The S-G (throughput versus offered load) performance of the DSVMA system and the blocking probabilities of both the second generation systems and the DSVMA systems are evaluated by the static analysis. A dynamic analysis of a system with finite number of terminals is also presented using an approximate Markov analysis method. Some numerical examples are given in the paper. As a result, it is shown that DSVMA can improve the channel utility efficiency of a circuit-switched TDMA (Time Division Multiple Access) wireless communication system and is directly applicable for second generation wireless information systems.

This paper proposes the reserved idle signal multiple access with collision resolution (R-ISMA/CR) protocol, which can maintain stability without being influenced by the retransmission probability. The R-ISMA/CR makes use of the multi-idle signals at the base station and the manipulating counter at the terminals. The performance of this protocol is evaluated by using the maximum throughput analysis and simulations.