We propose a new cognitive radio network architecture using the IP multimedia subsystem (IMS) functionality. We implement the cognitive radio network entities standardized in IEEE 1900.4 on the IMS that exchanges RAN and terminal context information between the networks and the terminals to make optimum and immediate reconfiguration decisions. In our proposed architecture, RAN context information is obtained from cellular networks which are directly connected to the IMS. The presence management functions of the IMS are applied to exchange those information in a “push” manner, which enables immediate notification of changes in wireless environment. We evaluate the performance of the proposed context information exchange method, by comparing with the cases that adequate and immediate RAN context information is not available. The evaluation results show that the proposed framework gives 10–30% superior performance than the conventional cognitive radio networks.

In cognitive radio systems using TV white space, it is desirable to secure a control channel to exchange the wireless network control information and to secure minimum frequency resource for secondary user communications if TV white space is unavailable. In order to satisfy these requirements, this paper proposes guard band utilization, which aggregates the multiple guard bands between digital TV signals and uses them for a control channel and/or a communication channel. To investigate the feasibility of the proposed scheme, this paper evaluates the performance degradation of the digital TV signals when the guard band is used. Furthermore, it discusses the permissible transmitting power and occupied bandwidth of the guard band signals to avoid the harmful interference to the digital TV signals.

In order to realize a future seamless high-speed road-vehicle communication system, we have proposed using code division multiplexing (CDM) radio transmission scheme by using cyclic shifted-and-extended (CSE) codes as spread codes. As the CSE codes are generated by cyclically shifting and extending a conventionally used code, the number of codes generated from a code is limited to the length of the shift interval and the tolerable period of delayed waves also depends on the length. In this paper, based on CSE codes, we propose a method to minimize the length of the shift interval and a cancellation technique with a simple calculation in order to eliminate the interference from delayed waves caused by the reduction of the length of shift interval. The concept and the BER performances in AWGN, two-paths, and multi-path fading environments are described in this paper. As a result, the maximum transmission rate of CSE-based-CDM transmission per one-code using the newly proposed transmission scheme is 3 times as large as that using conventional CSE codes and DQPSK-CDM transmission scheme.

This paper proposes a prioritized aggregation method that supports compressed video transmission on millimeter wave wireless personal area network (mmWave WPAN) systems. Frame aggregation is an effective means to improve system efficiency and throughput for wide band systems such as mmWave WPAN. It is required by the applications that the mmWave WPAN systems should provide Gbps or multiGbps transmission capability. The proposed scheme targets not only transmission efficiency but also support of compressed video transmission which currently is very popular. The proposal combines MAC layer aggregation with PHY layer skew modulation to facilitate the video transmission in a way that more important data is better protected. Simulation results show that the average peak signal to noise ratio (PSNR) performance is improved by 5 dB compared to conventional method, while the Gbps transmission requirement is fulfilled.

Accessing a geo-location database is one of the approaches for a secondary user (SU) to obtain the list of available channels for its operation. Channel availability is calculated based on information stored in the geo-location database and information submitted by the SU so that primary users (PU) are protected from harmful interference. The available channel checking process is modeled as a number of intersection tests between the protected contours of PUs and the operation area of the SU regarding to all potential channels. Existing studies indicated that these intersection tests consume time and introduce overhead to the database, especially when the contours or the operation areas are represented by n-polygons and the number of vertices n is a large number. This paper presents a novel method of determining available channels which reduces the number of intersection tests. By submitting SU's preferred channels or the number of channels to be checked to the database, the calculation time and database's load will be reduced significantly. This paper also presents analysis and simulation results of the database workload and the average number of channels obtained per query on different query methods. Suitable query method can be selected based on the number of similar channels in neighbor areas and the maximum number of intersection tests.

In this paper, we newly developed a small-size software radio terminal that can realize global positioning service (GPS) navigation system, vehicle information and communication system (VICS), electronic toll collection system (ETC), AM/FM radio broadcasting services on middle wave (MW) and very high frequency (VHF) bands, FM multiplex broadcasting system, and several modulation schemes such as BPSK, ASK, QPSK, GMSK, and π/4QPSK by downloading software to realize each system from wired and wireless networks. The developed terminal realizes simultaneous multiple services when users would like to use several radio communication services in the driving situation by using our proposed multitask algorithm. The developed terminal has a size of 17.5 cm wide, 19.0 cm deep, and 5 cm high and worked at DC-12.0 V and around 2 A. The size and electrical power consumption are quite small and low and acceptable for consumers such as car drivers. In this paper, we introduce the configuration and proposed key technologies in our developed terminal and measure the software configuration time.

This paper addresses thecurrent research and recent trends of image communications research that fall into the theme of intelligent communications in two parts --Intelligent Image Coding and Communications with Realistic Sensations. In Part , the theme of intelligent image coding and the particular example of encoding of human facial images using an intelligence-based approach is presented. A classification of the different generations--five generations--of image coding systems is first given. First and second generations are the direct wave-form coding and the statistical encoding methods. The third and fourth generations are the use of model-based anaylsis-synthesis and recognition/reconstruction methods, respectively. The fifth generation is the full intelligent coding system that can understand the semantics, intention, motives and other factors in an image. The progress in the model-based analysis-synthesis approach to image coding is reviewed and the particular example of its application to the encoding of human facial images is examined. In this example, the methods of modeling human face, the extraction of feature points and the tracing of motion in a facial image, as well as the analysis and synthesis of facial expressions are discussed. In Part , the current research in the new paradigm of telecommunication--Communications with Realistic Sensations is introduced. The progress in the research of a Virtual Space Teleconference System as an example of this new paradigm is presented. The possibility of delivering a very high level of sensation realism to a receiver is made real by recent advances in computer graphics and computer animation techniques, in stereoscopic display techniques that enable life-size images to be displayed on a wide screen and in computer human interface technologies, particularly, for recording human hand, head and eye positions. Progress of these technologies in the context of the research on the Virtual Space Teleconference System are discussed. The research on how to communicate and manipulate 3-D objects in a such an environment is examined.

In this paper we propose a new reconfigurable signal processing platform for SDR, having capability to change its processing parameters dynamically. On our proposed platform, while the wiring and processing scheme remain fixed, processing parameters and connections between processing modules together with the associated dataflow can be changed. We also demonstrate that our proposed signal processing platform has the new ability of easily composing new signal processing models dynamically, simultaneously with other tasks, and attaining high efficiency of logic usage.

A channel-hopping medium access control (MAC) protocol is proposed for cognitive operation of the 802.16d Mesh networks. The proposal mainly includes a channel-hopping algorithm of channel accessing for control messages transmission and reception, an algorithm of bandwidth allocation in cognitive operation, a cognition-enhanced frame structure, a method of spectrum sensing results reporting, and a method of incumbent detection. Compared to other studies, the channel-hopping algorithm for control messages transmission and reception requires no extra common control channels and operation of mesh clusters, thus it is more cost-effective and simpler in operation. Analysis shows that with this algorithm a Mesh node with any available channels has fair opportunities to receive beacon and network configuration information. Numerical results show that, compared to the mesh cluster method, the proposed channel-hopping algorithm has gain, e.g., as high as 3 times, in getting the data scheduling control messages received by one-hop neighbors, thus it has advantages in minimizing bandwidth allocation collisions. The algorithm of bandwidth allocation details the three-way handshake framework for bandwidth application and grant that is defined in 802.16d Mesh standard, and it enables dynamical resource allocations in cognitive operations. The feasibility of the channel-hopping MAC protocol is confirmed by simulations. And simulation results show that with the parameters set, a normalized aggregate saturation throughput of about 70% is achievable.

The feasibility of a dynamic zone configuration technique has been investigated. To make it easy to implement this technique in wireless communication systems, a simplified method for determining a suitable weight vector by using the least squares (LS) methods was developed. Simulations showed that the developed system is more effective than the present omni-directional zone system. Moreover, combining dynamic zone configuration technique with dynamic channel assignment strategy reduced blocking rate, forced call termination ratio, and required transmission power.

We propose new nulling vectors for the subcarrier grouping based low-complexity detection scheme of V-BLAST (vertical Bell Laboratories layered space-time) coded MIMO-OFDM. In each subcarrier group, the center subcarrier uses the conventional ZF-DFE (zero-forcing decision-feedback- equalization) algorithm and the non-center subcarriers use the reduced-complexity ZF-DFE with the new nulling vectors. The subcarrier grouping based detection scheme, ZF-DFE-SG, can significantly reduce the detection complexity compared with ZF-DFE-EX which exhaustively applies the conventional ZF-DFE at each subcarrier independently. The performance loss is very small. We conduct the simulations for channel coded V-BLAST OFDM system under estimated channel frequency responses. It is shown the complexity can be reduced by 80.6% with only 1.0 dB performance loss for a 44 system.

This paper proposes a hybrid multiband (MB) ultra wideband (UWB) system with direct sequence (DS) spreading. The theoretical error analysis for the DS-MB-UWB multiple access system with Rake receiver in the presence of multipath and narrowband interference is developed. The developed theoretical framework models the multiple access interference (MAI), multipath interference (MI) and narrowband interference for the designed UWB system. It is shown that the system error performance corresponding to the combining effects of these interference can be accurately modeled and calculated. Monte Carlo simulation results are provided to validate the accuracy of the model. Additionally, it is found that narrowband interference can be mitigated effectively in the multiband UWB system by suppressing the particular UWB sub-band co-existing with the interfering narrowband signal. A typical improvement of 5 dB can be achieved with 75% sub-band power suppression. On the other hand, suppression of UWB sub-band is also found to decrease frequency diversity, thus facilitating the increase of MAI. In this paper, the developed model is utilized to determine the parameters that optimize the UWB system performance by minimizing the effective interference.

In an AMS/OFDM system, base station is in control of the modulation level of each subcarriers, and then, adaptive modulated packet is transmitted from the base station to the mobile station. In this case, the mobile station is required the modulation level information (MLI) to demodulate the received packet. The MLI is generally transmitted as a data symbol, therefore, the throughput is degraded. Moreover, it is necessary to have some transmission delay times and the processing time to make an adaptive modulation command (AMC) using feedback information (FBI). With the FBI delay and processing time, the system performance might be degraded. To reduce these problems, in this paper, we propose a differential modulated pilot symbol assisted adaptive OFDM for reducing the MLI with predicted FBI.

This paper describes a color segmentation method which is essential for automatic diagnosis of stained images. This method is applicable to the variance of input images using a three-layered neural network model. In this network, a back-propagation algorithm was used for learning, and the training data sets of RGB values were selected between the dark and bright images of normal mammary glands. Features of both normal mammary glands and breast cancer tissues stained with hematoxylin-eosin (HE) staining were segmented into three colors. Segmented results indicate that this network model can successfully extract features at various brightness levels and magnifications as long as HE staining is used. Thus, this color segmentation method can accommodate change in brightness levels as well as hue values of input images. Moreover, this method is effective to the variance of scaling and rotation of extracting targets.

During these years we have been focusing on developing ultra high-data-rate wireless access systems. One of such kind of systems is called DPC-OF/TDMA [2]-[4] (dynamic parameter controlled orthogonal frequency and time division multiple access) which targets at data rates beyond 100 Mbps. In order to support higher data rates, e.g., several hundreds of mega bps or even giga bps, it is necessary to evolve DPC-OF/TDMA on MIMO-OFDM (multiple-input multiple-output orthogonal frequency division multiplexing) platform. In this paper, we propose two MIMO-OFDM evolution schemes for DPC-OF/TDMA: M1 scheme and M2 scheme. M1 scheme is based on the combination of V-BLAST (vertical Bell laboratories layered space-time architecture) and OFDM. It invests all transmit antennas on multiplexing while exploits no diversity in the transmitter. M2 scheme is based on multi-layer space-time block coded OFDM (multi-layer STBC OFDM). This scheme achieves a good compromise between multiplexing and diversity in the transmitter. We conduct exhaustive simulations for 44, 46, 48, 66, 68, and 88 systems. We are assured that both evolution schemes are very promising in supporting several hundreds of mega bps data rates. Moreover, we find that each evolution scheme has its own prevailing area. When the receive diversity order is limited, M2 scheme has better performance since it embeds transmit diversity; as the receive diversity order increases, the performance gap between the two schemes shrinks and finally M1 scheme prevails in performance. Therefore, the proper choice depends on the system configuration, i.e., how many transmit and receive antennas are used.

A method to synthesize facial caricatures with non-planar expression is proposed. Several methods have been already proposed to synthesize facial caricatures automatically, but they mainly synthesize plane facial caricatures which look somewhat monotonous. In order to generate expressive facial caricature, the image should be expressed in non-planar style, expressing the depth of the face by shading and highlighting. In this paper, a new method to express such non-planar effect in facial caricatures is proposed by blending the grayscale information of the real face image into the plane caricature. Some methods also have been proposed to generate non-planar facial caricature, but the proposed method can adjust the degree of non-planar expression by interactive evolutionary computing, so that the obtained expression is satisfied by the user based on his/her subjective criteria. Since the color of the face looks changed, when the grayscale information of the natural face image is mixed, the color information of the skin area are also set by interactive evolutionary computing. Experimental results show the high performance of the proposed method.

We have proposed two types of software download methods for software radio (SR) based intelligent transport systems (ITS): (1) broadcasting-type software download method and (2) communication-type software download method. In this paper, we study their feasibility of their employment in a newly developed prototype. We give tangible examples of method (1) using the vehicle information and communication system (VICS) and method (2) using the dedicated short range communication (DSRC) system. We describe the download formats and procedures for both methods and use the experimental prototype to evaluate the basic software download time and configuration time. Moreover we also propose architecture of SR-based multimode terminal that can reduce download time and utilize over-the-air software download services by VICS and DSRC links.

IEEE 802.15.3c has been standardized for wireless personal area networks (WPANs) to realize high-speed wireless communications with 1 Gbps throughput. In this paper we introduce a 802.15.3c WPAN prototype. The introduced 802.15.3c WPAN prototype applies the enhanced MAC functions of data separation on hybrid multiple access, long frame size, aggregation, block acknowledgment, and timing operation, which can realize Gbps throughput in IEEE 802.15.3c. Moreover, the experiment performance studies on the prototype show that around 1.6 Gbps throughput can be successfully achieved and video streaming applications can be accommodated. Also, our studies provide the useful information of MAC capacity for developing the 802.15.3c devices.

This paper proposes an autonomous relay access algorithm that provides an intelligent wireless network structure for inter-vehicle communication systems. The proposed algorithm introduces a special classification among mobile terminals and assigns terminals to one of several terminal groups, which are adaptively and autonomously constructed according to traffic conditions. The proposed algorithm uses the terminal groups to conduct relay access transmission among terminals, and achieves a high rate of successful inter-terminal transmission. Computer simulation confirms that the proposed algorithm can achieve a lower blocking probability than that without a relay access scheme.