This paper first presents an active integrated antenna configuration designed for broadband mobile wireless access systems using the 25-GHz band. This active integrated antenna comprises a microstrip antenna array and RF front-end circuits adopting spatial power combining schemes for reduced power consumption of the power amplifiers. Furthermore, the antenna and RF circuits are integrated into each side of a thick copper backing plate and both are connected through microstrip line /slot transitions. The developed active integrated antenna achieves the output power of 14.6 dBm and a noise figure of less than 5 dB. The wireless system using the developed active integrated antenna achieves a 6-dB improvement in the packet error rate compared to that using a passive antenna with the same array design as the active integrated antenna. Furthermore, we obtained the first license of the active integrated antenna for commercial use in high-speed wireless communication systems in Japan.

In this paper, we propose a blind adaptive channel identification and equalization algorithm with phase offset compensation for single-input multiple-output (SIMO) channel. It is based on the one-step forward multichannel linear prediction error method and can be implemented by an RLS algorithm. Phase offset problem is inherent part of any second-order statistics-based blind identification and equalization. To solve this problem, we use a blind adaptive algorithm called the constant modulus derotator (CMD) algorithm based on constant modulus algorithm (CMA). Moreover, unlike many known subspace (SS) methods or cross relation (CR) methods, our proposed algorithms do not require channel order estimation. Therefore, our algorithms are robust to channel order mismatch.

To accommodate best-effort multimedia Internet protocol (IP) connections in mobile environments, we introduced new criteria for TCP-friendliness and developed a control algorithm for the transient response and stability in the packet transmission rate. We improved the maximum throughput and QoS guaranteed congestion control algorithm (MAQS) by using these two solutions, and solved the following problems that Reno and conventional congestion control algorithms have: (1) network congestion cannot be avoided when the round-trip time (RTT) is short and the holding time is long, (2) the packet transmission rate of a long-RTT connection is small when it is multiplexed with short-RTT connections, (3) the packet transmission rate cannot be adjusted quickly when the channel capacity changes according to hand-off.

In this paper, a simple subcarrier selection combining technique is proposed for orthogonal frequency-division multiplexing (OFDM) systems with multiple receive antennas. The subcarrier-based selection algorithm is developed in the frequency domain to achieve an optimal selection combining gain for OFDM systems, instead of the antenna-based selection algorithms in the time domain or frequency domain. The proposed technique selects an optimal subcarrier with a maximum channel gain among all the receive antennas with the same subcarrier position, based on the estimated channel frequency response during the training period. Hardware complexity for the proposed technique is minimal since it requires single front-end with multiple receive antennas and single baseband demodulator. It is shown by computer simulation that a significant gain can be achieved by the proposed technique over the conventional selection combining technique for OFDM systems in practical situations.

We experimentally demonstrated a remote antenna system based on a millimeter-wave (MMW) over fiber scheme for 622-Mbps broadband fixed wireless access systems. In this system, the format of the RF signal is based on a four-carrier signal in which each carrier is modulated by using 64-QAM, to reduce the complexity of the RF system in comparison with the single-carrier QAM system using many more signal-points than 64. The remote antenna system based on the IF-over-fiber scheme was also experimentally demonstrated, as well as the MMW over fiber scheme for comparison. From the experimental results, we found that the remote antenna system based on the MMW over fiber scheme is effective not only from the viewpoints of miniaturization of the remote antenna station and ability to provide a stable millimeter-wave frequency, but also from the viewpoint of link performances such as allowable dynamic range and power penalty, even though the scheme's E/O and O/E devices have a higher cost.

One of the most basic characteristics of the image is accompanied by its blur. It was 1962 that I had discovered for the first time in the world that the blur was a Gaussian type. In this paper the outline is described about historical details concerning this circumstances.

A novel RF CMOS high Q-value active inductor is proposed in this work by using simple cascode RC feedback compensation technique. The performance of this active inductor has maximum Q-value about 1.2E6, inductance value from 3.5 nH to 4.5 nH and 3E-5Ω of minimum total equivalent loss, in the range of 1.2 GHz to 2 GHz.

We present low-cost millimeter-wave (MMW) photonic techniques for implementing gigabit/s wireless links. A passive mode-locked laser consisting of a Fabry-Perot laser and a single-mode fiber is used to generate 120-GHz optical MMW signals. We modulated these MMW signals by controlling the bias voltage of the photodiode. The MMW generation and modulation methods do not need expensive photonic components or high-power drivers. A link employing these low-cost photonic techniques achieved 1.25-Gbit/s wireless data transmission.

An optical FM system using an optical FM LD (laser diode) and an optical frequency discriminator (OFD), in which a nonlinear compensation scheme based on the interaction between its nonlinearities can minimize intermodulation distortion. This paper theoretically investigates the minimization influence for 3rd plus 5th order intermodulation distortion power for an optical FM radio-on-fiber system. The carrier to noise-plus-distortion power ratio (CNDR) is theoretically analyzed in employing the OFD whose transmission characteristic is controlled by a phase shifter. The results show that the designed receiver can achieve higher CNDR in the application of multicarrier transmission.

This paper proposes an efficient random access channel (RACH) transmission method that utilizes soft-combined consecutively retransmitted message data packets according to the Quality of Service (QoS) requirements for broadband multi-carrier/DS-CDMA (MC/DS-CDMA) in the reverse link. In the proposed scheme, the relative transmission power of a message from that of a successfully detected preamble for non-real time (NRT) type traffic data is significantly reduced by soft-combining several retransmitted message data packets thanks to time diversity since the delay requirement is relaxed. Meanwhile, for real time (RT) type traffic data, the relative transmission power of the message from that of the detected preamble is increased in order to reduce the packet error rate with a limited number of retransmissions. Simulation results elucidate that the total required average received signal energy per bit-to-background noise power spectrum density ratio (Eb/N0) for error-free transmission with time diversity for NRT type traffic data is reduced by more than 2 dB compared to that for conventional RACH without the relative transmission power control for a wide rage of fading maximum Doppler frequencies.

This paper presents laboratory experimental results on the throughput performance when key techniques such as adaptive modulation and channel coding (AMC) and hybrid automatic repeat request (ARQ) with packet combining are employed by an implemented transceiver based on the High-Speed Downlink Packet Access (HSDPA) air interface in a multipath fading channel. In AMC operation, we applied four modulation and coding schemes (MCSs): MCS1 (QPSK data modulation with the channel coding rate of R = 1/2, hereafter simply referred to as QPSK with R = 1/2), MCS2 (QPSK with R = 3/4), MCS3 (16 QAM with R = 1/2), and MCS4 (16 QAM with R = 3/4). The results elucidate that a peak average throughput above 5.0 Mbps is achieved at the average received signal energy per chip-to-background noise power spectrum density ratio (Ec/N0) of more than approximately 20 dB in a one-path fading channel; nevertheless, the achievable peak throughput becomes approximately 2.9 (2.6) Mbps due to severe multipath interference (MPI) in a two-path fading channel where the average signal power of the second path is 6 (3) dB lower than that of the first path, assuming nine-code-channel multiplexing with the fading maximum Doppler frequency of fD = 5 Hz. Furthermore, we clarify that although the throughput performance employing Type-II hybrid ARQ (i.e., Incremental redundancy) is almost the same as that employing Type-I hybrid ARQ with packet combining (i.e., Chase combining) in a two-path fading channel, Incremental redundancy exhibits superiority over Chase combing in a one-path fading channel for a high Doppler frequency channel such as fD = 80 Hz.

A "rooted" plane triangulation is a plane triangulation with one designated vertex r and one designated edge incident to r on the outer face. In this paper we give a simple algorithm to generate all connected rooted plane triangulations with at most m edges. The algorithm uses O(m) space and generates such triangulations in O(1) time per triangulation without duplications. The algorithm does not output entire triangulations but the difference from the previous triangulation. By modifying the algorithm we can generate all connected (non-rooted) plane triangulations with at most m edges in O(m3) time per triangulation.

The present paper introduces a new approach to the construction of a class of ternary sequences having a zero-correlation zone. The cross-correlation function of each pair of the proposed sequences is zero for phase shifts within the zero-correlation zone, and the auto-correlation function of each proposed sequence is zero for phase shifts within the zero-correlation zone, except for zero-shift. The proposed sequence set has a zero-correlation zone for periodic, aperiodic, and odd correlation functions. As such, the proposed sequence can be used as a finite-length sequence with a zero-correlation zone. A set of the proposed sequences can be constructed for any set of Hadamard sequences of length n. The constructed sequence set consists of 2n ternary sequences, and the length of each sequence is (n+1)2m+2 for a non-negative integer m. The periodic correlation function, the aperiodic correlation function, and the odd correlation function of the proposed sequences have a zero-correlation zone from -(2m+1-1) to (2m+1-1). The member size of the proposed sequence set is of the theoretical upper bound of the member size of a sequence having a zero-correlation zone. The ratio of the number of non-zero elements to the the sequence length of the proposed sequence is also .

We propose a new resource management scheme, Distributed Channel Allocation Protocol (DCAP), for multimedia Ad hoc Wireless LANs (AWLANs). This scheme implements a Quality-of-Service (QoS) providing distributed resource management on the Orthogonal Frequency Division Multiplexing-Code Division Multiple Access (OFDM-CDMA) channel architecture. According to the performance evaluation results for MPEG traffic sources, DCAP can be a good choice of resource management scheme for AWLANs supporting multimedia services on the Broadband Wireless Access (BWA)-type physical layer.

A frequency-tuning method in the microwave region, which maintains a high unloaded Q-factor, was demonstrated using a double-sapphire-loaded cavity which operates on the Whispering Gallery mode, WGH9,1,0. Two adjacent nominally identical sapphire cylinders were positioned in a copper cavity and tuned by changing their relative coupling. A frequency tuning range of 85 MHz and a maximum unloaded Q-factor of 1.3 105 was experimentally measured at room temperature. This is only 13% less than the single resonator Q-factor, which is a small compromise to pay for the increased tuning capacity.

This Letter presents a fast codeword search algorithm based on ordered Hadamard transform. Before encoding, the ordered Hadamard transform is performed offline on all codewords. During the encoding process, the ordered Hadamard transform is first performed on the input vector, and then a new inequality based on characteristic values of transformed vectors is used to reject the unlikely transformed codewords. Experimental results show that the algorithm outperforms many newly presented algorithms in the case of high dimensionality, especially for high-detail images.

This paper proposes an ROF ubiquitous antenna architecture for the wireless CDMA system. The proposed system separates each component of independent signals passing through the multipath in radio and optical links, which are gathered at passive double star link, by using RAKE reception and the macrodiversity effect is obtained. Theoretical analysis shows that the proposed system improves BER performance by 22 dB and reduces the transmission power and its control range by 19 dB.

A decentralized estimation system usually contains a number of remotely located local sensors that can pre-process observed signal and convey the processed data to a fusion center that makes a final estimation. The local sensors are linked to the data fusion center by transmission channels. When the observation (or estimate of parameter) is quantized at the peripheral sensors and an assumption of conditionally independent sensor data is made, due to potential communication constraints on the channels, the problem of quantization design and bandwidth allocation among the channels linking local sensors to the fusion center is studied in this letter.

A novel optical modulation scheme is proposed for synthesizing a pair of dual-mode optical BPSK signals with an orthogonal phase relationship via a LiNbO3 Mach-Zehnder modulator (MZM) with dual RF signal inputs and a carrier suppression feature, which enables the generation of a crosstalk-free QPSK signal at the photodetection stage. With this method, one can compensate the drawback, that is bandwidth broadening, in our previously proposed method where a dual-mode optical QPSK signal is generated on the basis of narrow-angle modulated QPSK signal injection into a double-sideband suppressed carrier MZM device. We have carried out experiments for 60 GHz performance demonstration of this QPSK signal generation mechanism, and the results indicate the effectiveness of the present scheme.

The emerging multimedia applications for future mobile communication systems typically require highly diversified Quality of Service (QoS). However, due to the time and location dependent fluctuating nature of radio resources in the radio link, it is very difficult to maintain a constant level of QoS with the current end-to-end QoS control only. Therefore, wireless-aware QoS is the key issue for achieving better end-end QoS. In this paper, a new wireless QoS scheme for a joint CDMA/NC-PRMA cellular system are proposed considering QoS prioritization mechanism, users' diversified requirements and the harmonization with IP-QoS. Two wireless QoS-aware resource allocation algorithms are proposed to support QoS prioritization while achieving high radio resource utilization. By introducing a set of new QoS resource request parameters (minimum, average and maximum requirements), the algorithms can assign radio resource in a more flexible way than the conventional fixed resource allocation. Computer simulations indicate that the proposed QoS algorithms exhibit superior performance with respect to packet dropping probability for realtime application users, and improve transmission rate for non-realtime application users, which evince the effectiveness of the proposed wireless QoS algorithms.