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In this paper, the newly proposed designed antenna with low profile has overcome physical problems of the existing antenna for the aircraft or vehicles, and have performance suitable for wideband characteristics. The proposed antenna was designed with a half-wavelength hemispherical structure by applying the self-complementary principle and image theory. The size of antenna is 400 mm(diameter) × 200 mm(height). As a result, and the radiation patterns are similar to monopole antenna. Next, the structure of a redesigned rectangular a half-wavelength loop antenna for easy of fabrication. This antenna has a size of 196 mm(width) × 156.3 mm(height) × 158.7 mm(length). The radiation patterns are similar to the monopole antenna of a half-wavelength hemispherical structure. Finally, we newly proposed a low-profile wideband antenna to ensure a low-profile structure, while retaining the wideband characteristics. The low-profile wideband antenna has a size of 315 mm (width) × 110 mm(height) × 295 mm(length). The radiation patterns of the antenna are similar to those described earlier. Therefore, it is a new type of low profile and ultra wide band(100:1) antenna suitable for mounting the aircraft or vehicles.

In this paper, we propose the SNR weighted LLR combining method in uplink mmWave multi-beams environment. Until now, the mmWave band has been considered as a candidate for new radio band for 5G mobile communication system. Because the mmWave band has good directivity, we can make sharp beam by applying beamforming technology using a plurality of antenna elements. The BS can have the antenna configuration for 3D beamforming and the UE can have the antenna configuration for circularly-switched beamforming for multi-beams communication. In the above situation, the uplink beam forms wider than the downlink beam and the transmitted signal energy of UE is distributed widely throughout the receive antennas of BS. Therefore, we propose the SNR weighted uplink LLR combining method for effective uplink performance in the above situation. Through the link-level simulation, we show the effect on the SNR weighted LLR combining of the uplink receiving beams and compare the coded BER performance of the suggested method with that of no weighted LLR combining method.

This paper presents architecture of the PTN-OTN integrated switch fabric module which supports 3.2 terabit switching capabilities in optical-circuit-packet converged transport network systems. The switch fabric module supports not only PTN-OTN converged switching function between integrated line cards that support PTN and OTN traffics, but also provides system timing synchronization function to each line cards and mate switch fabric cards.

Generally in OFDM system, we intentionally set the FFT start point offset for the purpose of preventing from ICI in the perspective of implementation, but it will bring phase rotation that can not be compensated by simple LS channel estimation. Therefore, in this paper, we showed that uncoded BER performances were enhanced by the phase compensation method when we used the FFT start point offset in the presence of received time synchronization errors.

In this paper, several methods of carrier frequency offset (CFO) estimation for IEEE 802.16m WirelessMAN-Advanced are suggested and their performances are verified. Fractional part of CFO can be measured using time-domain repetition, and two types of repetition can be utilizable in IEEE 802.16m: the cyclic prefix and PA-preamble. Comparing the CFO measurement performance of the two methods by computer simulation, effective method of CFO measurement in IEEE 802.16m system is suggested.

The Schmidl and Cox (SC) packet detector uses the ratio of the power of a received packet and the power of its own packet delayed by the periodicity of preamble. If the ratio exceeds a ratio threshold (T) with a non-zero value less than one, the SC packet detector declares that a packet is detected. However, it can make a false detection when there is a DC offset during no packet. This paper has proposed the modified SC packet detector with two limiters to increase the probability of correct packet detection even if there is a DC offset.

The decision-directed blind equalization algorithm is often used due to its simplicity and good convergence property when the eye pattern is open. However, in a channel where the eye pattern is closed, the decision-directed algorithm is not guaranteed to converge. Hence, a modified decision-directed algorithm using a hyperbolic tangent function for zero-memory nonlinear function has been proposed and applied to avoid this problem by Filho et al. But application of this algorithm includes the calculation of hyperbolic tangent function and its derivative or a look-up table which may need a large amount of memory due to channel variations. To reduce the computational and/or hardware complexity of Filho's algorithm, in this paper, an improved method for the decision-directed algorithm is proposed. It is shown that the proposed scheme, when it is combined with decision-directed algorithm, reduces the computational complexity drastically while it retains the convergence and steady-state performance of the Filho's algorithm.

In this paper, we analyzed the available frame synchronization error ranges through the uncoded BER (bit error rate) performance in the condition of 64-QAM digital modulation in Mobile-WiMAX system.

This paper finds the optimum input bit size of FFT engine in WiBro system through the uncoded-BER performances of computer simulation.

Due to the development and proliferation of ubiquitous technologies and services, various sensor network applications are being appeared on the stage. The needs for algorithms requiring complex signal processing with a high-performance processor such as digital signal processor are also increased. However, it is difficult to use such processor for the low-power sensor network operating with a battery because of power consumption. This paper proposes and implements hardware and software architecture of the hybrid-type sensor module composed of a low-power sensor module and a high-performance sensor module for the complicated signal processing in the wireless sensor node. Although this approach needs some additional hardware, it results in some improvements in operation time supporting complex algorithms for target detection in the sensor networks.

GPON Extender is required to extend transmission reach in GPON. In this paper, we propose simple activation techniques and a burst reset controller for the extender, and discuss experimental results of the Extender with CWDM links.

There are some leakage radiations from human body depending on incoming signals to it. As there are many noises in the frequency band spanning several MHz, human body communication (HBC), which is a technique to transfer various information through the human body as a communication channel, requires a limitation of frequencies and data rates to support a reliable network that can cope with interference from adjacent users and electrical devices. This paper proposes a frequency selective baseband transmission (FSBT) for HBC. FSBT requires no RF/IF components or overhearing in sleep mode as a service based on Touch-And-Play (TAP). The proposed HBC system supports high reliability, low power consumption, and low cost through FSBT. We achieved a biterror rate of 10–6 at 2 Mbps without forward error correction and verified the functions of the prototypes to transfer streaming data or image files between ultra-mobile PCs, or an ultra-mobile PC and printer.

Due to the proliferation of technologies and services related with wireless sensor network, various sensor network applications are being appeared on the stage and a lot of sensor network testing technologies are being studied. However, most of testing systems or testbeds have objective for test and evaluation of sensor network protocols. For testing sensors and evaluating signal processing algorithms, it is necessary to develop a testbed for those purposes and especially, for monitoring the high speed sensing data. This paper proposes and implements a wireless sensor network testbed for controlling sensors, getting and managing the real-time sensing data on the remote sites.

In this paper, a new cell-averaging constant false alarm rate (CA-CFAR) detector based on minimum selected cell in sub-reference windows (SRW) is proposed. It takes the minimum cells in sub-reference sliding windows for rejecting some strong interferences or alleviating the clutter-edge effect surrounding the test cell, and then it uses the general cell-averaging technique to detect the target. Under Swerling II target fluctuating model, the analytic expressions of PFA, PD and the average detection threshold (ADT) of the proposed CFAR detector are derived. By the performance comparison with other schemes through the simulation, it is found that the detection performance of minimum selected cell averaging (MSCA)-CFAR has a similar performance to that of OS-CFAR in nonhomogeneous background with strong interfering target.

In this paper, we propose a GAS-CP-CDMA(cyclic-prefix code division multiple access system that uses Sequences with good autocorrelation property) and analyze the uplink signal-to-noise ratio performance of that system. Phase-shifted sequences are used for differentiating users. The signals of the GAS-CP-CDMA system experience no (or very little) interferences from co-cell signals because of the good autocorrelation property, but user signals of adjacent cells may yield interferences. The frequency reuse factor in the ordinary CDMA system is around 0.6 and the interference from adjacent cells is about 40 percent of the total interference in the conventional CDMA system. Our numerical analysis shows that the frequency reuse factor and user capacity versus signal-to-noise ratio of the GAS-CP-CDMA system are improved comparing to the conventional CDMA system. The uplink user capacity of the proposed system can be increased up to about twice of that of the conventional CDMA system.

In this paper, we propose a preamble pattern for upstream cable modem and develop the synchronization and channel equalization schemes suitable for the proposed preamble pattern. The proposed preamble consists of the concatenation of the oversample constant amplitude zero autocorrelation code (CAZAC) sequences of length 32. Not only provides relatively good frame detection performance due to the good auto correlation properties of CAZAC sequence, the proposed preamble pattern can be easily employed in initial automatic frequency control due to the repeated structure.

This paper proposes an efficient AGC scheme before mobile synchronization only using the existing hard-ware engine for AGC scheme after synchronization.

The upstream of digital cable modem is a burst mode transmission system, where a burst contains the preamble and data. In this paper, we consider algorithms for the symbol timing, carrier frequency- and phase-offset recovery for the upstream cable modem, that are compliant to DOCSIS 2.0. Several algorithms are tested and verified to find the best algorithm for each of the three recovery blocks, respectively. To fit to the DOCSIS specification, Oerder & Meyr's is chosen for the timing recovery algorithm, Mengali & Morelli's is chosen for the carrier frequency-offset recovery algorithm and Cartwright's is chosen for blind carrier phase recovery. We decide the optimal preamble length for these algorithms and check the error variance. Finally, we show the error performance of the entire system.

This paper presents a new location based service (LBS) that can be provided in digital multimedia broadcasting (DMB) transmission system economically and effectively. We propose a point of interest (POI) protocol compatible to transport protocol experts group (TPEG) and introduce the POI data server and the verification platform implemented by using the proposed protocol. As a filed result, the stability and effectiveness of proposed protocol is verified.

In this paper, we propose keep-alive algorithm based periodic ranging code group (PRCG), in which the periodic ranging code is divided into groups and the AP (access point) performs this algorithm when the periodic ranging code arrives at AP in WiBro (wireless broadband Internet) system. In order to increase the radio bandwidth resource efficiency in this system, we propose keep-alive algorithm for finding abnormal AT (access terminal). From the numerical results, our proposed PRCG algorithm can support more radio resource efficiency compared to message-driven keep-alive algorithm.

OFDM systems are very sensitive to the phase noise. The phase noise in OFDM has two side effects: common phase error (CPE) and intercarrier interference (ICI). Especially, the rotation of constellation caused by CPE may be fatal in coherent schemes. This paper suggests an equalizer coupled with a phase tracking algorithm to combat frequency selectivity and to correct CPE. Computer simulations prove that CPE can be reduced by the phase tracking loop with low complexity.

This paper studies an automatic gain control (AGC) algorithm used in mobile cellular systems. The AGC design includes the determination of the precision of quantizer and a circuit to keep the input power of quantizer constant to minimize the quantization noise generated from the analog-to-digital conversion process. The proposed algorithm illustrates the method to determine the required precision of quantizer and to set the design parameters of the AGC in a mobile cellular system. The validity of the proposed algorithm is verified by computer simulation.

This paper describes a method to implement mobile number portability (MNP) in Korea. The MNP system consists of two function blocks, one the call processing system and the other the subscriber management system. The hardware structure and processing method of the system are presented in this paper. The call processing system uses the QoR method and consists of intelligent network exchanges and local number portability database (L-NPDB) system. The subscriber management system consists of the interconnection system of master-NPCDB (NP customer database, M-NPCDB), local-NPCDB, M-NPDB and L-NPDB. The master database is interconnected to the local database through a dedicated line and can process any MNP service in real time. The presented MNP structure in this paper has been implemented in Korea and the result is quite successful.

The general frame structure of current orthogonal frequency division multiplexing (OFDM) systems is based on the reservation-based time division multiple access (TDMA). The TDMA frame consists of a number of bursts, which are the transmission formats of the physical layer. Since the OFDM/TDMA uses broad bandwidth consisting of a large number of narrow bands, even the size assignment for the smallest burst is so large that a good throughput cannot be expected where a fine granularity is required. In this paper, we suggest an idea to obtain fine granularity effectively and to improve the system throughput greatly.

This paper proposes an algorithm to combat the performance degradation of an IEEE 802.11a orthogonal frequency division multiplexing (OFDM) system under the time-varying channel conditions by supplementing the conventional channel estimation method that uses a preamble. Packets in wireless local area network (WLAN) systems consist of preamble symbols for channel estimation and data symbols for traffic transmission. There are some pilots inserted within each data symbol to correct the phase error due to the frequency offset remaining even after the automatic frequency control (AFC) The proposed algorithm utilizes the pilots and requires a small amount of additional hardware. The validity of the proposed algorithm is verified by computer simulation.

Unlike in the IS-95 based synchronous CDMA system, each base station (BS) operates asynchronously and use Gold code sequence in the 3GPP asynchronous WCDMA system. Therefore, for soft handover (SHO) case, the searching time for all active set members of BS becomes very long. In order to maintain good link quality during the handover execution, it is very important to reduce the handover search time for the target BS. In this paper, we propose an efficient searcher architecture and algorithm to reduce handover search time for asynchronous WCDMA system. We introduce double dwell serial searcher architecture with dual scrambling code generators and search algorithm, which reduce search time in handover environment with small increase of hardware complexity. Average search time performance of proposed scheme is analyzed for soft handover environment. And the real threshold values of search mode and verification mode are investigated. The results analyzed in this paper may be applied to the designing of the user equipment (UE) multi-path searcher of 3GPP WCDMA system.

As the demand of down link high speed data packet service such as wireless Internet increases, the standardization for high speed downlink packet access (HSDPA) in wideband code division multiple access (WCDMA) system is in progress. HSDPA adopts adaptive modulation and coding (AMC) scheme, which changes the modulation level (for example, M-PSK, where M=4, 16, etc.) and channel coding rate adaptively to wireless channel conditions to maximize throughput. To adopt AMC, the receiver should measure the signal energy to interference power spectral density ratio (SIR) as the channel quality for feedback to the transmitter. The SIR estimation method, which has been used for the conventional voice services, was un-biased and had no problem in case of low power, low data rate, and low cell loading (i.e., single code transmission). However, the bias error of the conventional method increases as the transmitter has higher power, higher data rate, and more full loading (i.e., multi-code transmission), which are typical of the HSDPA service environment. To solve this problem, this paper proposes and verifies the validity of a SIR estimation method using the symbol patterns which are conventionally used to separate the pilot signals of transmit antennas. This paper also shows the method is always un-biased even with the HSDPA service environments.

A multiprotocol label-switching paradigm of integrating layer 3 routing with layer-2 technology such as ATM etc. has been proposed as an alternative to today's router architecture. When MPLS is applied to an ATM-LSR, a VC merging function that merges pluralities of ingress streams into one single stream is required to support scalability of MPLS networks. We will present the VC merging card that is implemented using a field programmable gate array (FPGA), and a high performance SAR device. The card provides not only high flexibility in the MPLS networks but also noble management method of connection setup and termination for multipoint-to-point connection essential to the VC merging function.

In this paper, we present an efficient architecture of turbo decoder for IMT2000 system. We introduce a base 2 logarithmic maximum a-posteriori algorithm (log/sub 2/MAP) whose architecture is simpler than that of the conventional natural logarithmic MAP algorithm (log/sub e/MAP). With log/sub 2/MAP, we obtain a '2 function' which is simpler than the 'E function' used by log/sub e/MAP. In order to implement the architecture of the 2 function, we use approximated binary logarithmic algorithm (ABLA) which has been usefully adopted in DSP. Using ABLA, we can reduce the RAM size from 1 kbytes to 96 bytes, which can be implemented using combinational logic gates. Also, we design the simple normalization module by making all the branch metrics to have positive values. We introduce reverse interleaver and deinterleaver to calculate forward and reverse state metric simultaneously. Using our architecture, we obtained BER of 9.79/spl times/10/sup -7/ at Eb/No of 2 dB and 5th iterations for constraint length K=4, code rate R=1/2, jumping window of 512 bits and interleaver size of 1144 bits, i.e. data rate of 57.6 kbps.

Doppler filter bank (DFB) is the heart of pulsed Doppler radars. It provides the residue clutter elimination and coherent integration. With the improvement of digital signal processors (DSPs), the implementation using them is becoming more common. Generally, for the DFB to process the input data in real time, the parallel processing concept using multiple DSPs is used. This paper presents the implementation of a programmable DFB using ADSP21060s. By analyzing the transfer rate of the data received during coherent processing interval (CPI) and formulating the time required to compute the algorithm, the total processing time and the number of ADSP21060s to implement the DFB are estimated.

Bolt degradation has become a major issue in the nuclear industry since the 1980s due to failure during operation. This paper presents a method of detecting the existence and size of a small crack in a root between two crests in threads using ultrasound. The key idea is from the fact that the Rayleigh wave propagates slowly along a crack from the tip to the opening and is reflected from the opening mouth. When there exists a crack, a small delayed pulse due to the Rayleigh wave is detected between large regularly spaced pulses from the thread. The delay time is the same as the propagation delay time of the slow Rayleigh wave and is proportional to the size of the crack. The slow Rayleigh wave is efficiently detected by a pulse shaping technique based on a modified least squares method.

This paper proposes an improved power control method, changing the target bit energy per noise spectral density (Eb/No) threshold with adaptive up and down step sizes in variable fading environments. We carry out computer simulations and hardware experiments for verification of the method. The new method results in better frame error rate (FER) and Eb/No performance than the existing ones.

This paper presents the effects of an algorithm for controlling the base station's received target signal-to-interference ratio (SIR) according to the quality of the received frames on the capacity enhancement. It is proved that the algorithm presented has a smaller mean of the actual SIR received at the antenna than the existing method which applies the fixed target SIR needed for the worst case to all the users at every time instant. It is also shown that the capacity of the system can be further increased by optimizing the system parameters in the algorithm.

An analytic model for the algorithm controlling base station's received target signal-to-interference ratio (SIR) to maintain a pre-set frame error rate (FER) is derived. It is shown that the model can be used to find the optimum control step size for various wireless environments. The numerical results based on the analytic model are similar to the simulation results. As the probability of the assumed discrete speed change increases, the average target SIR increases but the optimum control step size decreases.

This paper presents some channel estimation methods adequate for the space time transmit diversity (STTD) receiver that coherently demodulates signals from each path of two transmit antennas. The STTD mode receiver estimates the channel information of each antenna path from the received common pilot channel (CPICH) signals with known orthogonal patterns transmitted by two antennas at the base station. The conventional channel estimation methods using a pilot filter result in serious inter-antenna interference caused by imperfect orthogonal processing of signals between the two antennas. Another drawback is the inter-symbol interference caused by lack of orthogonality between two symbols Which is the basic premise of the STTD decoding algorithm. This paper analyzes the effects of the inter-symbol interference and proposes some robust channel estimation methods to reduce the effects of the inter-symbol interference; This paper also compares the performance of the proposed channel estimation methods in various fading channel environments through the effective signal to interference ratio (SIR) and the bit error rate (BER).

This paper describes an analysis of repeater effects in a CDMA system. The use of repeaters is very cost-effective when the service providers want to overcome coverage holes and enlarge the coverage area. But the repeater acts as a new source of interference to the neighboring cells. It may have an influence on wireless networks and could result in lowering of quality. Therefore this paper analyzes the effect on wireless networks by a repeater in positive and negative aspect.