Anterior cruciate ligament (ACL) injury causes knee joint instability, and affects on sports performance. Therefore, ACL reconstruction is essential to keep their performance high and to prevent osteoarthrosis. It is well known that the outcome of ACL reconstruction is strongly related to the placement and orientation of the bone tunnel. 2-D X-ray radiograph and CT images have been used to evaluate the placement and orientation of the bone tunnel. Quadrant method evaluates the bone tunnel placement based on the Blumensaat's line which has high intensity on 2-D X-ray lateral radiograph. There is problem of invasiveness using X-ray radiograph or CT image. Therefore, we have proposed an MR image based computer-aided surgical planning of ACL reconstruction. The system evaluates the bone tunnel placement and orientation based on Quadrant method. The remained problem of our system is Blumensaat's line is manually determined. This paper proposes that a method to synthesize the pseudo lateral radiograph from MR images, and extract the Blumensaat's line on the synthesized pseudo lateral radiograph. The experimental results showed that the proposed method successfully determined the Blumensaat's line on the pseudo lateral radiograph.

A continuous-switching type array antenna receiver has been proposed in order to reduce the deterioration due to fast-fading channel variations and improve communication performance. The receive antennas are placed in a linear array, and by sequentially switching the elements in the opposite direction to the direction of the train travel, it has been possible to fix the signal receiving point virtually. Through the development of a scale-model experiment of high-speed movement using the prototype antenna, in this paper we show that it is possible through optimized antenna element selection and appropriate signal processing to reduce the fading rate and improve the performance of an OFDM system. A software simulation based on the Worldwide Interoperability for Microwave Access (WiMAX) physical layer parameters was made and data transmitted at RF in a 5 MHz bandwidth with symbol rate appropriately scaled to simulate a range of fading speeds. The receive antenna array consisting of eight elements traverses a track at a virtual speed of 180 km/h and the error rate performances with and without switching are compared.

Anterior cruciate ligament (ACL) injury causes knee joint instability, and effects on sports performance. Therefore, ACL reconstruction is essential to keep their high performance. It is well known that the outcome of ACL reconstruction is strongly related to the placement and orientation of the bone tunnel. Therefore, optimization of tunnel drilling technique is an important factor to obtain satisfactory surgical results. Current procedure relies on arthroscopic evaluation and there is a risk of damaging arteries and ligaments during surgery. The damages may reduce the accuracy and reproducibility of ACL reconstruction. As a postoperative evaluation method, a quadrant method has been used to evaluate the placement and orientation of the bone tunnel in X-ray radiography. This study proposes a computer-aided surgical planning system for evaluating ACL insertion site and orientation using magnetic resonance (MR) images. We first introduce MR image based the quadrant method to determine the ACL insertion site for preoperative patients. It also evaluates the 3-D spatial relationship between the planning femoral drilling hole and arteries around the femoral condyle. This system has been applied to ACL injured patients, it may increase the accuracy and reproducibility of ACL bone tunnel, and it can evaluate a risk of damaging the surrounding arteries and ligaments.

The neonatal cerebral disorders severly languish the quality of life (QOL) of patients and also their families. It is required to detect and cure in their early stage for the sake of decreasing the degree of symptoms. However, it is difficult to evaluate neonatal brain disorders based on morphological analysis because the neonatal brain grows quickly and the brain development progress is different from person to person. Previously, we proposed a method of calculating growth index using Manifold learning. The growth index is effective to evaluate the brain morphological development progress, although, it does not directly correspond to the brain development delay. To evaluate brain development delay, this paper proposes an estimation method of neonatal brain age using Manifold learning, principal component analysis, and multiple regression model. The regression model is trained using a 4-D standard brain, which is constructed using training subjects with growth index. To evaluate the proposed method, we constructed a multiple regression model using 11 normal subjects (revised age: 0-4 month old), and estimated brain age of 4 normal subjects. And, we estimated brain age of 4 abnormal subjects to evaluate the detection accuracy of brain development abnormality. The results showed that the method found the differences of brain development for abnormal subjects.

Recent theoretical and experimental studies indicate that spatial multiplexing (SM) systems have enormous potential for increasing the capacity of corresponding multiple input multiple output (MIMO) channels in rich scattering environments. In this paper, we describe two fast detection algorithms for the standard BLAST receiver. The first algorithm covers the nulling and cancellation (NC) detection interface that applies inflation and deflation recursion to the initialization and iteration stages, respectively. The second algorithm utilizes the QR decomposition (QRD) detection interface that reuses Cholesky decomposition and back substitution, leading to an alternative low complexity detector. Compared with the conventional fastest method, our new algorithms reduce the complexity of the preprocessing by a factor of about 2. Furthermore, they are also implementation friendly by avoiding the recursive permutation and permitting the function reuse.

Recent studies indicate that spatial multiplexing (SM) systems have enormous potential for increasing the capacity of multiple input multiple output (MIMO) channels in rich scattering environments. In this paper, we present two efficient decision feedback equalization (DFE) algorithms for signal detection of SM scheme. The basic idea behind the new proposals is to reduce the complexity by separating the order search and filter generation. Compared with the conventional DFE detectors with optimal and suboptimal ordering rules, the new algorithms are less complex and achieve error performance that closely approximates that of the standard Bell Labs layered space time (BLAST) algorithm

This paper describes the performance of transmit antenna selection for an eigenbeam multiple-input multiple-output with orthogonal frequency division multiplexing (MIMO-OFDM) system as measured in a testbed implemented with field programmable gate array (FPGA); it also targets wireless LANs. For this verification, we employ the determinant-based transmit antenna selection approach based on the estimated instantaneous MIMO channel matrix to reduce the computational complexity. The measured packet error rate (PER) performance confirms that the eigenbeam scheme with three-select-two antenna selection scheme provides a slight degradation in required carrier-to-noise power ratio (C/N), approximately 0.2 dB from the eigenbeam-only scheme, but with significantly lower computational complexity. Furthermore, with regard to the impact of Doppler frequency, we focus on the transmission interval between MIMO channel estimation and data transmission. To suppress the degradation in required C/N to within 1.5 dB, a transmission interval of approximately 15.0 ms is permitted without using the re-estimation procedure in fd= 5 Hz, for eigenbeam 16QAM/MIMO-OFDM with three-select-two antenna selection

This paper proposes a simplified decision-feedback channel tracking scheme for multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems designed for wireless LANs. In the proposed scheme, the channel matrix for each subcarrier is tentatively estimated from a replica matrix of the transmitted signal. A number of the estimated channel matrices, each determined for a different timing, are combined, and the previously estimated channel matrices are replaced by the latest ones. The packet error rate (PER) performances for the proposed scheme are evaluated by computer simulations. Assuming 5 GHz band operation, the proposed scheme keeps the PER degradation at PER=10-2to less than 1 dB when the velocity of transmitter is less than 11.8 km/h. The result represents the proposed channel tracking scheme provides sufficient mobility for wireless LAN systems. We also evaluate the computation complexity of the proposed scheme. The proposed scheme requires less than 1% of the complex multipliers needed by the conventional channel tracking scheme based on Kalman filters.

Recent studies indicate that spatial multiplexing (SM) scheme has enormous potential for increasing the capacity of MIMO channels in rich scattering environments. In this paper, we present a new MMSE decision feedback equalization algorithm for signal detection in SM systems. The new algorithm separates the order search and the filter generation to avoid recursive ordering operations. Compared to the earlier MMSE-DFE detectors with optimal and suboptimal ordering rules, the new algorithm is less complex and achieves a bit error rate performance that closely approximates that of the standard BLAST algorithm.

In this paper, we propose a new algorithm for zero-forcing decision feedback equalization (ZF-DFE) in multiple input multiple output flat Rayleigh fading channel. The basic idea is to separates the layer ordering and the filter construction operations, thus making both operations tractable and efficient. The new layer ordering strategy approximates the optimal ordering rule (VBLAST) from a geometrical perspective, and the filters in proposed ZF-DFE are constructed using a matrix Cholesky decomposition aided QR decomposition. Compared to the conventional ZF-DFE detectors utilizing optimal and suboptimal ordering rules (SQRD), the proposal is complexity efficient. Additionally, the bit error rate performance of the new algorithm significantly approximates that of the optimal ordering ZF-DFE. Thus a practical signal detection scheme for the vector channel is found.

Fairness in the number of effective opportunities for wireless access between the uplink and downlink and that between stations cannot be achieved in wireless packet communications such as wireless LANs due to the packet error caused by packet collisions or received power degradation. In this paper, we propose fair wireless access control with error compensation (FWAC/EC) to achieve fairness over an unstable link. The key features of the proposal are release delay control and packet compensation control. The point of the release delay control is to control the waiting time for attempting a subsequent transmission after an ongoing transmission. The point of the packet compensation control is continuous transmission based on the number of retries. Simulation results show that FWAC/EC achieves fairness in the number of effective opportunities for wireless access between the uplink and downlink and that between stations over an unstable link.

This paper describes the experimental performance of transmit antenna selection in a multiple-input multiple-output with orthogonal frequency division multiplexing (MIMO-OFDM) system as measured in a testbed implemented with field programmable gate array (FPGA); it also targets wireless LANs. In this experimental verification, we employ the determinant-based transmit antenna selection approach based on the estimated instantaneous MIMO channel matrix to reduce the computational complexity. The measured packet error rate (PER) performance confirms that the antenna selection scheme provides an approximately 3.5 dB improvement in the required carrier-to-noise power ratio (CNR) of 16 QAM/MIMO-OFDM. Furthermore, with regard to the impact of Doppler frequency fd, we focus on the transmission interval between the MIMO channel estimation and data transmission. To suppress the degradation in required CNR to within 1.0 dB, a transmission interval of approximately 13.3 ms is permitted without using the re-estimation procedure in fd=5 Hz, QPSK/MIMO-OFDM.

This paper describes the experimental performance of eigenbeam multi-input multi-output with orthogonal frequency division multiplexing (MIMO-OFDM) systems as measured in a testbed implemented with field programmable gate arrays (FPGA). The testbed offers 1/5-scale real time signal processing. Extensive experiments on the testbed confirm the basic operation and performance of eigenbeam MIMO-OFDM with 16QAM. From the PER performance, we confirm that the eigenbeam scheme with permutation matrix and three transmit antennas (Mt= 3) drastically improves the required carrier-to-noise power ratio (CNR) by approximately 5.6 dB over the scheme without eigenbeam with Mt= 2. Furthermore, to determine the impact of Doppler frequency, we focus on the transmission interval between the MIMO channel estimation and data transmission. To suppress the required CNR degradation to within 1.5 dB, it is found that the eigenbeam scheme with permutation matrix and Mt= 3 permits a transmission interval of approximately 15.5 ms when fd= 5 Hz

The mesh topology based on the standard IEEE 802.11 for wireless LANs appears to be a very promising architecture for achieving a ubiquitous wireless Internet access in the future. However, the current IEEE 802.11 protocol is aimed at single-AP (access point) environments and many problems related to the wireless meshed interconnection of APs and mobile terminals (MTs) remain to be solved. Some proposed solutions to build such mesh architectures are based on single-channel ad-hoc oriented schemes in which IEEE 802.11 protocol has been modified. The main problem with this type of schemes, however, lies in the very low performance of the single-channel architecture itself. The task group S of IEEE 802.11 is currently working out standards for IEEE 802.11-compliant mesh architectures in a number of usage scenarios including residential, office and campus/community/public access network but a lot of work remains to be done since the group was established just on last year. In this paper we propose a new multi-radio multi-channel mesh architecture for hot zones which works using a distributed coordination function (DCF)-based technique for interconnecting APs and a simple but effective radio routing mechanism. A major advantage of our proposed scheme is that, putting routing issues aside, it introduces no change into the MAC protocol of IEEE 802.11. Our simulations results obtained in OPNET show the great effectiveness of radio routing for balancing the traffic load within the network as well as interesting results related with the size of packets and the mesh architecture itself that could lead to further research in the future. Moreover, the results show the proposed architecture yields a very good performance in terms of total throughput and transmission delay

The asynchronous transfer mode (ATM) employs header-error control (HEC) to protect the ATM cell header from bit error and/or avoid the misforwarding of ATM cells. However, wireless ATM systems require a more powerful forward-error correction (FEC) scheme to offer acceptable bit-error rate (BER) performance. This paper proposes the utilization of FEC, which makes it possible to discard ATM cells more reliably. Time-division multiple-access (TDMA) is very suitable for wireless ATM systems. In the TDMA scheme, synchronization is very important. This paper also proposes to combine FEC with unique word (UW) detection for improving TDMA synchronization characteristics.

This paper describes the performance of an outage free SDH (synchronous digital hierarchy) interface 256 QAM modem. An outage free DMR (digital microwave radio) is achieved by a high coding gain trellis coded SPORT QAM and super multicarrier modem. A new frame format and its associated circuits connect the outage free modem to the SDH interface. The newly designed VLSI's are key devices for developing the modem. As an overall modem performance, BER (bit error rate) characteristics and equipment signatures are presented. A coding gain of 4.7dB (at a BER of 10/sup /spl minus/4/) is obtained using SPORT 256 QAM and Viterbi decoding. This coding gain is realized by trellis coding as well as by increasing of transmission rate. Roll-off factor is decreased to maintain the same frequency occupation and modulation level as ordinary SDH 256 QAM modem.>

This paper describes the performance of a 256 QAM modem with 400 Mbit / s transmission capacity. A variety of novel techniques are introduced as ways to achieve good performance. Key techniques include 1) an accurate 256 QAM modulator employing a new monolithic multiplier IC, 2) a carrier recovery circuit which satisfies such requirements: good phase jitter performance and no false lock phenomenon, 3) a highly stable high-level decision circuit, and 4) a forward error correcting code. As an overall modem performance, BER characteristics and signatures are presented. The equivalent CNR degradations of 1 dB(at BER of 10-4) and 2 dB (at BER of 10-9)are obtained using a single Lee-error correcting code and a seven-tap baseband transversal equalizer. The residual bit errors are decreased below the order of 10-10. The performance of a 256 QAM multicarrier modem has given prospect for the development of 400 Mbit/s digital microwave radio system.