Leaky coaxial cable (LCX) is widely used for wireless communication systems as an antenna for a linear-cell, which covers long and shallow areas. Since one LCX is usually utilized as one antenna, more than one LCX is required to configure a multi-input multi-output (MIMO) system. It means it is costly and space-consuming. To resolve these problems, we proposed a novel MIMO method for LCX. In this paper, we propose the method to utilize one composite cable, which consists of a pair of LCXs with different radiation characteristics, to configure a 4 × 4 MIMO channel. The measurement results confirmed that the proposed composite cable can realize a good channel condition for 4 × 4 MIMO transmission even if it is put in an anechoic chamber where no reflection path exists. On the other hand, the results also confirmed that it has good channel condition even if the spacing between a pair of LCX is as small as 2cm for the 5GHz band. Therefore the proposed system can reduce the space requirement for MIMO deployment for wireless application over linear-cell environments to cope with the high rapid increase of consumer electronics devices.

This paper studies a multi-satellite multi-beam system with single frequency reuse which applies the MIMO (Multi Input Multi Output) technique. To improve the spectral efficiency of satellite systems in support of broadband communications, MIMO is the one of the most important approaches. Since it was difficult to achieve high spectral efficiency by simply combining a multi-beam system with single frequency reuse and a multiple satellite system, this paper newly proposes a pre- coding technique that takes account of the frequency offsets caused by the multiple satellites. We then evaluate our proposal by a cumulative distribution function (CDF) related to channel capacity and show the improvement of the spectral efficiency compared to the conventional satellite systems.

Leaky coaxial cables (LCX) have been widely used as antennas to form linear service areas for radio communication systems. Such services of linear cells have been deployed inside tunnels, along railways, and so on. Usually, one LCX is utilized as one antenna. Therefore it requires more than one LCX to configure an multi-input multi-output (MIMO) system. In this paper, we propose a MIMO system using single LCX, which can be utilized as two antennas. When different RF transmit signals are fed to each end of the proposed cable, single LCX can work as two antennas. To confirm the feasibility of the proposed MIMO system, we conduct experiments to measure the characteristics of 2 × 2 MIMO channel using single LCX. The results confirm that our proposed 2×2 MIMO channel using single LCX can realize a good channel condition for MIMO transmission even within a highly correlated propagation condition. The proposed MIMO system using LCX will release the space requirement and reduce the cost of system for configuration of LCX MIMO system especially with large number of LCXs. It benefits the design and configuration of LCX-MIMO system for many scenarios of linear-cell.

The aim of this study is to develop a methodology for evaluating public anxiety arising from disaster events and to clarify the nature of crisis communication between the government and citizens. Preparing for catastrophes that may happen in the future is an important issue in risk management. In the Great East Japan Earthquake, Twitter was used widely as a means of sharing information about the disaster. This paper proposes a methodology for measuring anxiety by determining semantic orientations of risk assessments and clarifying the contents and structures of crisis communication systems by referencing the corpus of government announcements and Twitter during the week after the Great East Japan Earthquake. Objectivity of this paper has been ensured by applying natural language processing and text mining techniques based on corpus linguistics.

The aim of this study is to develop a computational framework for analyzing the framing of news coverage for controversial public issues by comparing the coverage from ideologically distant news media sources. Because news media sources play a key role in the formation of public opinion, their coverage also plays a major role in the dynamics of the public debates. It can be hypothesized that the public interactions of political players may be treated differently in the media based on the editorial perspective of the media sources in question and the positions that the political players occupy in the political arena. However, the question arises, how can these differences be measured? Using corpus extraction techniques, SPARQL queries, and ontology engineering, this study compares the positions that key political players occupy in discourse spaces that are modeled by two ideologically distant news media sources based on the same controversial public issue.

In this study, the authors develop a model of the generating process on peeling/falling (P/F) of protective covering concrete as a counting process. The model is able to consider a time-independent factor (random event) and a time-dependent factor (deterioration event) of P/F process. In detail, the random event is presented by the homogeneous Poisson process, the deterioration event is presented by the non-homogeneous Poisson process where arrival rates are changed with time. Then, a mixed Poisson deterioration process is formulated by both the homogeneous and the non-homogeneous Poisson process. Lastly, the appropriateness of the proposed model is discussed empirically, by applying it to actual inspection data. By estimating the mixed Poisson deterioration model, it is possible to predict the generating process on P/L of protective covering concrete. The proposed model is able to represent three things at the same time. Firstly, the number of P/F concrete increases if an inspection interval increases. Secondly, the model formulates the deterioration event that the number of P/F concrete increases with accelerating speed if an inspection interval increases, which is unable to be presented by homogeneous Poisson model. Lastly, the model stands for the random event that is generated even if the service life is small, which is unable to be presented by non-homogeneous Poisson model. Moreover, the model makes possible to classify observed data stochastically by the generating factor which is the random event or the deterioration event.

During the operation of multiuser multiple-input-multiple output (MU-MIMO) algorithms, some antennas of BS or UEs may neither transmit nor receive signals due to the long distance or unexpected damages. Therefore, the BS cannot obtain the channel state information (CSI) from/to these antennas. Without these CSI, the performance of algorithm is degraded. We call this effect as `broken antenna effect (BAE)'. To cope with this issue, this paper proposes a process to regularize the channel matrix by replacing the missing CSI with zero(s) and setting nonzero values to diagonal elements. Then, it is confirmed through computer simulation that the proposed method can adjust the number of transmitting parallel streams according to the number of `broken' antennas, and provide MU-MIMO transmission with maximum diversity order without any change of the precoding process.

This paper introduces Direct Spectrum Division Transmission combined with a novel phase compensation method that offers improve frequency utilization efficiency. The proposed method divides a single-carrier modulated signal into multiple sub-spectra in the transmitter (Tx) side and assigns each sub-spectrum to an unused frequency slot. It combines them in the receiver (RX) side without phase distortion. To prevent phase discontinuity after spectrum combination due to propagation delay, we propose a novel phase compensator that estimates the phase difference between sub-spectra to compensate Rx sub-spectra; no specific frame pattern is required. A simulation shows that the degradation in required C/N is negligible. The results confirm that the proposed method realizes highly accurate phase compensation.

This paper analyzes the disclosure policies of critical infrastructures under the threat of terrorism by use of subjective game theory. A terror risk of critical infrastructures depends on terrorists' motive to attack them. Therefore, it is expected that the proper implementation of protection and disclosure about critical infrastructures can contribute to the reduction of terror risk. To analyze the disclosure policies, this paper introduces a virtual figure of the government named “naive government”. Countries which do not have continuous relationships with terror groups have not regarded the threat of terrorism as their actual risk which threatens their society. It is often the case where the government and the citizens share common knowledge that the government does not take any countermeasures against terror attacks. This paper refers to such a government figure as “naive government”. Under the common knowledge of naive government, this paper analyzes the disclosure policies about 1) the government's warning level, and 2) the implementation of protective countermeasure against terror attacks. It is shown that both of the disclosure policies are effective with respect to the reduction of terror risk. In addition, it is shown that the latter disclosure policy is superior to the former policy.

In this paper, we consider a multi-attribute tender for project procurement, where the contractor is selected on the basis of price and quality. We analyze the tendering behavior of potential contractors in multi-attribute tenders and show that social surplus is maximized through competitive bidding with consumer-surplus-based quasi-linear scoring rules. We consider the case in which the aim of the government is to achieve socially efficient levels of quality that maximize social surplus and simultaneously improve the expected utility for the government. In order to achieve this aim, the introduction of the optimal lower limit of the bidding score is important. In addition, we analyze a price-only tender and describe the optimal ceiling price in a price-only tender as a special case of a multi-attribute tender.

In this paper, the contract schemes for construction projects in the developing countries are formulated in the form of an incomplete contract model, whereby the double moral hazard issues driven by the owners as well as contractors are investigated. The effort levels of the owners and the contractors are supposed to be unverifiable and mutually complementary with respect to costs risk reduction. It is shown that the moral hazard by the owner, who transfers the excessive cost overrun caused by the owner's indulgence to the contractor, may trigger the moral hazard by the contractor; thus, the moral hazard issues by the owner may lead to the overall inefficiency of the project. In this paper, the optimal risk allocation scheme between the owner in the developing countries and the contractor, which can deter the double moral hazard issues and enhance the project efficiency, is theoretically investigated.

This paper analyzes the government's disclosure strategies for critical infrastructure against potential terror attacks. Any event that disrupts the functioning of critical infrastructure such as power plants, airports, and water management systems will have a major impact on the society. As such, it is very important for the government to protect such infrastructure from threats by establishing proper disclosure strategies. The government usually finds it difficult to accurately assess the terror risk because the government does not have sufficient information about the terrorists' capabilities and motives. Therefore, implementation of an anti-terrorism policy depends on the government's subjective decision. Considering this, the paper formulates the game between the government and the terrorists as a subjective game. It is found that the government's disclosure of the implementation of counter-terrorism measures increases the government's subjective utility, but does not necessarily lead to an increment in the government's objective utility.

This paper proposes a new Variable Polarization Frequency Division Multiplexing (VPFDM) demodulator for Ku broadband mobile satellite communications. VPFDM allows each user to utilize multi-carrier frequency slots of the Vertical and Horizontal polarizations simultaneously. Since the VPFDM demodulator cancels cross-polarization interference by using signal processing, the user station can use a simple antenna that does not track polarization. In this paper, we introduce a new VPFDM demodulator with adaptive multi-carrier modulation (AMCM); it can vary the modulation level carrier by carrier to enhance frequency and power efficiency. We then propose a noise and frequency offset tolerant AFC that is the key to the success of AMCM. Finally, simulation results show its excellent performance.

One of the core techniques for the Pavement Management Systems (PMS) is the deterioration hazard model. The hazard models stochastically forecast the deterioration progresses of pavement based on its historical performance indicators over time. This paper introduces a class of hazard models, which consider the heterogeneity factors by a local mixing mechanism. Special attention is paid to the formulation of transition probability of condition state, which is subjected to follow Markov chain. The paper further introduces optimization approach for selecting best repair strategy based on discounted life cycle cost analysis. The application of the model targets to minimize exposing risks to road administrators. The usefulness and practicability of the model are examined through life cycle costs evaluation with real data of Vietnamese highway system.

In this paper, a theoretical model is developed to analyze the effect of the performance specification scheme in a public procurement problem on the contractors' incentives for technological development and for moral hazard. Considering the variety of technical needs in construction projects, we have pointed out that the performance specification fosters the matching the technical needs of each work with a contractor endowed with the relevant professional expertise who can deal with those needs most efficiently. We have proven that such a matching mechanism motivates contractors to develop new technologies. Moreover, we have pointed out that the role of performance tests in alleviating the contractors' moral hazard for excess cost saving by adopting unreliable new technology.

The aim of this study is to develop a computational method of discourse analysis based on corpus semantics. The objective is to achieve an accurate understanding of the debate content through the topic extraction and semantic similarity from the public debate minute corpus by using a multi-method which includes TFIDF, T-VSM, and MDS. The main issue of public debate and the inconsistency level between participants’ utterance could be described by using the method. The methodology presented in this study is applied to a case example. Finally, the applicability of the proposed methodology to practical debates is discussed.

This paper proposes a methodology for the valuation of menlal damage caused hy a flood disaster using the Contingent Valuation Method (CVM) and analysis of covariance struchlre5. The unobserved mental discomfort or the victims of a Rood disaster is expressed quantitatively as a structural concept. which is used as the explanatory variable of the victims’ utility function in order to meawre their tnental damage. The structural concept of the mental damage, which is consider.

This paper analyzes moral hazard problems in PPP (Private-Public-Partnership) projects. Moral hazard is classified into two types: the Special Purpose Company’s (SPC) and the bank’s moral hazard. In a regular tender process, the SPC’s moral hazard cannot be deterred. A reserve tender system can do it better in deterring the SPC’s moral hazard, though at the same time it might induce the bank’s moral hazard. Furthermore, the SPC’s moral hazard is triggered once the bank’s moral hazard occurs. The paper concludes that the bank’s monitoring is valid for the deterrence of the moral hazard of the SPC and the bank.

To develop large capacity high quality mobile satellite communication systems in the future, a multi-beam that can cope with extremely high levels of frequency reuse must be used. We describe a novel resource allocation scheme that enables systems to contend with ever-changing user distribution and inter-beam interference conditions. The proposed scheme simultaneously controls various kinds of radio resources, such as transmission power, frequency bandwidth, and modulation parameters. It adapts them to each user depending on the radio propagation environment. Our performance evaluations demonstrate that the scheme can satisfactorily allocate multi-beam satellite resources to greatly increase communication capacity and still improve the communication quality, thus ensuring QoS under various user distribution and traffic conditions.

This paper formulates a subjective trust game in order to investigate the trust formation processes between a truster and a trustee, who have different cognitive schemes. Furthermore, as the institutional designs to build a trust relationship between them, alternative forms of third party reviews, i.e., (1) a single reviewer, (2) multiple reviewers, (3) multiple reviewers with interpreters, are presented. Especially, an optimal composition of reviewers in the third party is examined for the mechanism of checks and balances among the members to be worked well.

In this paper, we analyze the economic benefit of the deposit and the subsidy policy for infrastructure PFI (Private Finance Initiative) projects. One of the most substantial characteristics of PFI projects related to infrastructure facilities is existence of the external benefits. The objective of the SPC (Special Purpose Company) is to maximize the profit generated from the project. Therefore, with considering the external benefit of the PFI project related to infrastructure facilities, a private sector may have incentive to liquidate a valuable project in terms of social welfare. In this paper, we argue that the deposit policy and the subsidy policy implemented by the government play a role in giving an incentive to continue a valuable project. This paper shows that the policy which is a combination of deposit and subsidy policy payment can improve the efficiency of a PFI project with external benefits under the condition that the external benefit of project is uncertain.

To realize advanced broadband mobile satellite communications, this paper proposes a new wireless access approach named variable polarization frequency division multiplexing (VPFDM); it assigns the resources created by dual polarization states as well as frequency bandwidth to customers. The most significant problem in using dual polarization is cross-polarization interference. For satellite communications, when existing terminals and/or satellites employs asynchronous frequency conversion of V/H polarizations, received signals undergo a mixture of frequency offsets. Aiming to overcome this satellite-specific problem, we propose a novel VPFDM modem that can handle multi-carrier multi-rate dual polarization signals. The results of simulations and experiments show that the proposed modem is applicable to satellite communications.

To obtain large capacity, high quality future mobile satellite communication systems, we must use a multi-beam that has extremely high levels of frequency reuse. This paper describes a novel resource allocation scheme for multi-beam satellite communication systems that can dynamically offer maximum communication capacity without compromising quality. The scheme optimizes the frequency bandwidth, satellite transmission power, modulation level, and coding rate to each beam to deal with the ever-changing user distribution and inter-beam interference conditions. First, to minimize interference, we clarified the optimal constraint conditions when all clusters share the same bandwidth, while consuming the system bandwidth. We then used them as constraints in the optimization algorithm that allocates resources to each beam. Second, to manage the various needed resources and adapt them to the beam gain and interference levels at user locations, we propose two schemes for allocating resources within a beam. As a result, although both schemes were able to accommodate the same number of users, the fixed power with adaptive modulation secured a more stable communication quality. This means that our scheme can satisfactorily allocate multi-beam satellite resources, while increasing communication capacity and improving quality

We propose a simple configuration, low coupling gap-filler that can re-transmit signals at the same frequency in which they were received to enhance service areas for next-generation satellite communication networks. To suppress coupling between the receiving and transmitting antennas, this gap-filler uses two transmitting antennas that form a null in the direction of the receiving antenna by controlling the amplitude and phase of one transmitting antenna. Results of simulations and field experiments show that the proposed on-frequency gap-filler is feasible and can greatly suppress coupling

Referendums in which imperfectly informed individuals are called to vote for or against a public project can result in inefficient outcomes, as compared to the outcomes that would arise with completely informed individuals. In this paper, an incomplete information game is presented to investigate the influence of interest groups' voices on individuals' judgments. It is shown that in the case individuals' judgments on the credibility of the groups' voices are based on the groups' efforts, a limited number of interest groups utilize their voices in strategic fashions and try to prevent a referendum outcome containing the majority will. Alternative institutional designs are introduced to overcome this inefficiency, and some problems regarding the referendum processes are discussed.

In this paper, a three-period model with debt overhang is proposed to analyze the mechanism that a risk-neutral firm calls for earthquake insurance. If the firm needs to make an additional investment to continue operation due to an earthquake, the firm must procure liquidity assets immediately. However, the firm may confront debt-overhang problem, which mean that the firm cannot procure for the additional investment. This paper shows earthquake insurance can alleviate such a debt-overhang problem.

This paper investigates an economic methodology for project evaluation, which explicitly incorporates evaluation costs and the option value of flexibility in decisions. The traditional cost-benefit analysis is fundamentally based upon a 'now or never principle', and fails to evaluate the option value derived by reserving decisions to wait for more concrete information. In this paper, the real option model is formulated to determine the optimal timing strategy for project evaluation and implementation. The optimal solutions of the model can be obtained by solving the integral equation models. This paper is concluded by illustrating numerical examples to demonstrate the availability of the methodology.

This paper describes a compensation technique for the gain/phase imbalance of quadrature demodulators for direct conversion receivers. In this compensation method, the power measurements for the imbalance estimation can be done in less than ten symbol periods of the test signals. This means that our compensation method does not need as many iterative cycles using the least mean square method or discrete Fourier transformation required by previous methods. Experimental results show that the differences between the estimated and actual values are small: the gain imbalance was less than 0.35 dB, and the phase imbalance was less than 1.2/spl deg/.

This paper presents a new automatic-frequency control (AFC) configuration capable of removing a large amount of frequency offset (up to about +/- 0.625 fs, where fs means symbol rate of signals). The new configuration consists of an AFC that removes frequency offsets between +/- 0.125 fs and another MC that detects the frequency offset range coarsely between +/- 0.625 fs. First, the principle of the new AFC configuration is described. The performance of the new AFC configuration is confirmed via computer simulation. It is shown that the proposed configuration can accommodate wide range frequency offsets as u ell as reduce the acquisition time.

Individuals are faced with two types of uncertainty when they are expected to vote the best alternative for a certain project: one is whether the individuals' interests are common upon the government's interest and the other is whether the project is better or worse for them. In this paper, an incomplete information game is formulated to investigate communication processes between a government and an individual. The model describes how the individual is motivated to believe what the government says. Alternative message systems are presented in order to encourage the individual to trust the government. It is shown that the information systems to verify whether the individual's interests are common upon the government's interests can induce the individual to make a rational choice of the project alternatives.

This study investigates an influence of catastrophic damage caused by natural disaster on international market. In case a large country in the world economy is damaged, fiscal policies for recovery from disaster vary rates of return in international capital market and consequently affect consumption and investment behavior of households even undamaged countries. This study formulates an overlapping-generation-model, which contains two counties, to investigate international externality in dynamic reconstruction process and strategic tax policies adopted by two national governments in the market where source-based taxation rule is applied. The government of the damaged country is motivated to discount tax rates on capital income in order to attract international capital, causing outflow of capital from the undamaged country. The study further investigates the tax-subsidy policies by the government of the undamaged country to mitigate the negative externality, and refers to possibility of tax competition.

In this paper, a bargaining game model with two-sided outside options is presented to investigate the resolution mechanism of disputes under FIDIC Conditions of Contract, Red Book. Most disputes in construction contacts stem from disaccord in contractual interpretation. When a dispute arises, each party has two options between agreement and arbitration. Under FIDIC, either party has the right of calling in the arbitrators and the arbitral award binds the parties. While the mechanism of the dispute resolution process involves a complicated negotiation process, we focus on the mechanism of dispute resolution on the claim, which the contractor asserts, and propose a model by which we analyze the criteria for the choice between agreement and arbitration in the process.

In this paper, the risk sharing rules an investigated to characterize the contractual structure of the project contracts. The authors exclusively focus upon the GCW and the FIDIC forms, which can be regarded as typical examples of incomplete contract forms. Risks involved in construction works are classified into exogenous and endogenous ones. The paper claims that dear differences in both contract forms in coping with endogenous risks can be found, while there are no essential differences in dealing with exogenous ones. The paper concludes by summarizing the remaining research issues to be scrutinized in the future.

A bi-directional multimedia satellite communication system has been proposed to support high-speed Internet access. This system utilizes a low-cost user earth station with an ultra-small antenna for easy installation. Since this system utilizes ultra-small antennas, it employs the low-power spread spectrum (SS) scheme in the access link to keep the off-axis equivalent isotropic radiation power below the limit. For efficient use of transponders and frequency, SS signals are superposed on the high-speed TDM forward link signal. To demodulate access link signals under this condition, two novel technologies are introduced. They are the adaptive interference cancellation technique, and the parallel and staggered operation SS demodulation technique. This paper describes system configuration, the new technologies and the results of a system performance evaluation in an experiment. The results of the evaluation demonstrate that superposed transmission over the forward link and low-power access link signals is feasible.

The paper investigates the roles of public assistance for PFI (Private Finance Initiative) projects. In order to realize PFI projects, it is sometimes necessary for the public sectors to induce the private sectors to participate in the projects by giving financial assistance The guaranties-of-liabilities are the basic means for public sectors to share part of the financial risks with project companies. A guaranty-of-liabilities model is presented to investigate the efficient risk sharing schemes between the private and public sectors.

This paper focuses upon the optimal repairing rules of public systems under demand uncertainty. An optimal impulse control model is formulated to determine the optimal sequence of impulse timing: and the recovery policy to minimize the present values of expected life cycle costs. The optimal repairing rules can be formulated as a set of adaptive state-dependent rules. The repairing rules can be applied based upon updated observations about service levels of systems. A numerical example illustrates how adaptive rules can be calculated in a given demand environment.

Recent progress on application of interactions between optical near-field and nanoscale materials and atoms is reviewed. Photochemical vapor deposition of Zn dots and lines with the size of sub-100 nm has been realized by using an ultraviolet optical near field. Deposition of nanoscale ZnO is also revealed. Manipulation of atoms is then described to control the thermal motion of atoms in high vacuum. Experimental and theoretical results of manipulation by using optical near field generated on a prism surface, hollow fiber, and fiber probe are presented. Finally, quantum theoretical treatment of optical near field is given.

This paper presents a very low power consumption one-chip baseband large-scale integrated circuit (LSIC) for personal communication terminals. It comprises a /spl pi//4-shift QPSK modem, an adaptive differential pulse code modulation (ADPCM) codec, a time division multiple access time division duplex (TDMA-TDD) controller and a link access procedure for a digital cordless (LAPDC: Layer-2 protocol) controller. The developed LSIC meets all the specifications of the personal handy-phone system (PHS) standard. By employing a novel coherent demodulator and an ADPCM codec with a click noise suppressor, a higher quality voice transmission has been achieved in a fading environment. In addition, it has 61-kb/s data transmission capability to achieve wireless multimedia services based on PHS. Moreover, the novel circuit configurations of the modem, the ADPCM codec, the TDMA-TDD controller, and the LAPDC controller achieve significant power reduction of the baseband circuits (57.4 mW) of personal communication terminals. It enables very low power consumption wireless multimedia terminals to be achieved based on the PHS common air interface.

Diversity combining methods for mobile satellite communication systems employing convolutional encoding and soft-decision Viterbi decoding are evaluated. Computer simulation clarifies that the pre-Viterbi-decoding maximal ratio combining method has better performance than other methods in Rician fading channels. The simulation results agree with the Pe (bit error probability) performance derived from the numerical analysis for slow fading using the approximate Pe performance of Viterbi decoding in AWGN (additive white Gaussian noise) channels and the probability density function of Rician fading. Applying this diversity method to the multi-beam mobile satellite communication systems, a satellite beam diversity reception scheme is proposed. A computer simulation result shows that the proposed scheme decreases the packet error rate of the control signals to less than 1/100 around the satellite beam boundary.>

This paper proposes a full digital modem employing a reverse-modulation type carrier recovery scheme for offset type modulation schemes. The full digital modem employs a wave forming filter for reverse-modulation of offset type modulated signals to increase the extracted carrier signal-to-noise ratio. The proposed modem achieves both high speed carrier acquisition and low carrier slipping rate simultaneously which other methods cannot achieve. Computer simulation results show that the proposed modem applied to OQPSK systems achieves a low carrier slipping rate performance of less than 1.0*10/sup -7/ event/symbol at an Eb/No of 4 dB with negligible bit error rate degradation. The proposed modem can be implemented in all-digital circuits and suitable for LSI implementation.>

A DCF (dual carrier filter) reverse-modulation-type carrier recovery circuit is proposed to achieve a low carrier skipping rate and satisfactory phase tracking performance for coherent detection of PSK (phase shift keying) signals in fast Rician fading channels. The proposed scheme employs both narrow and wide bandwidth carrier filters simultaneously for the reverse-modulation-type carrier recovery circuit. It is clarified by computer simulation that the Pe performance of a QPSK (quadriphase shift keying) modem employing the proposed scheme shows an improvement of 1.5 dB in required E/sub s//N/sub O/ at Pe=10/sup 4/ (after Viterbi decoding (R=7/8, K=7), C/M (direct-to-multipath signal power ratio)=10 dB, interleaving size=64*64), compared with conventional coherent detection employing the reverse modulation tank-limiter scheme or the Costas loop scheme.>

A DCF (dual carrier filter) reverse-modulation-type carrier recovery circuit is proposed to achieve a low carrier skipping rate and satisfactory phase tracking performance for coherent detection of PSK (phase shift keying) signals in fast Rician fading channels. The proposed scheme employs both narrow and wide bandwidth carrier filters simultaneously for the reverse-modulation-type carrier recovery circuit. It is clarified by computer simulation that the Pe performance of a QPSK (quadriphase shift keying) modem employing the proposed scheme shows an improvement of 1.5 dB in required E/sub s//N/sub O/ at Pe=10/sup 4/ (after Viterbi decoding (R=7/8, K=7), C/M (direct-to-multipath signal power ratio)=10 dB, interleaving size=64*64), compared with conventional coherent detection employing the reverse modulation tank-limiter scheme or the Costas loop scheme. >