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Microwave and Wireless Components Letters, IEEE

Issue 8 • Date Aug. 2003

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Displaying Results 1 - 23 of 23
  • Guest editorial special issue on 2002 European Conference on Wireless Technology

    Page(s): 293 - 295
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    Freely Available from IEEE
  • Preconditioned astigmatic beam tracing for urban propagation

    Page(s): 296 - 298
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (227 KB) |  | HTML iconHTML  

    In wireless communication network planning, deterministic and statistical propagation tools have been developed. Astigmatic Beam Tracing, a deterministic method based on ray tracing (GO/UTD), can be applied to urban propagation modeling. A numerical code has been applied to a model of urban scenario with increasing complexity. The results of a numerical analysis are discussed to evaluate the relevance of the test case size on the computational charge. View full abstract»

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  • Mixed traffic in UMTS downlink

    Page(s): 299 - 301
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    The traffic being transferred within 3G mobile networks will be composed by different information flows with various constraints on the required QoS (bit rate, delays, etc.). In this scenario, flexibility will be a key point for the success of 3G systems. UMTS (Universal Mobile Telecommunication System) offers both circuit switched and packet switched transfer mode, and within each transfer mode, different QoS can be achieved by properly setting physical parameters such as the spreading factor of the physical channels, the power control scheme, the rate of the FEC protecting code, etc. In this letter, we give an evaluation of the downlink performance of W-CDMA UMTS radio interface when providing access to multimedia services. In particular, we analyze through simulations a typical scenario where voice calls and Web-browsing sessions share the same frequency carrier, the former using the dedicated channels (DCH), the latter being transferred on the downlink shared channel (DSCH). View full abstract»

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  • Implementation of signal processing algorithms for 3G and beyond

    Page(s): 302 - 304
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    For communication systems of third generation and beyond, the algorithmic complexity will increase significantly compared with 2G and 2.5G systems, as we can see from the example of channel estimation. The answer to these demands will consist of transceivers with re-configurable hardware accelerators in advanced CMOS technology. View full abstract»

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  • Free-space optics communication systems: first results from a pilot field-trial in the surrounding area of Milan, Italy

    Page(s): 305 - 307
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    A multiple FSO field-trial has been deployed in the surrounding area of Milan, Italy. After a brief description of the setup we focus our attention on the factors impacting system availability. In particular, we will investigate the effect of visibility and turbulence. View full abstract»

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  • Application of convolutional error correcting codes in ultrawideband M-ary PPM signaling

    Page(s): 308 - 310
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    The interference issues related to ultrawideband (UWB) radio pose tight restrictions on the maximum data rate of UWB radio telecommunication systems. A possible solution is to reduce the required signal to interference ratio (SIR) that gives satisfactory performance to the UWB system. In this letter, we propose coded M-ary UWB radio communication systems. Two classes of convolutional codes, namely, low-rate superorthogonal codes and high-rate punctured codes are considered for this purpose. Simulation results on the bit error rate of the proposed system indicates that the system is capable to work in lower SIR's and therefore supports higher data transmission rates in a real interference environment compared to the previously proposed UWB communication systems. View full abstract»

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  • Efficient WISH in an indoor environment

    Page(s): 311 - 313
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    With the diffusion of wireless connections to Internet, the number of complex operations carried out from mobile users is increasing. To cope with bandwidth limitations and with disconnections, data caching is the most used technique. However for complex operation like dynamic searching a better solution is to take advantage of the multichannel property offered by CDMA protocol. In this case, cached documents can be allocated on distinguished channels in a dynamic way to obtain a better utilization of the radio communication links. We study a particular caching strategy suitable to be integrated with a radio-channel policy. We consider a semantic caching for intranet queries (or intranet searching) that takes advantage of data semantics by caching query answers instead of pages in order to exploit similarities between different queries. In fact, in a WLAN scenario, Internet activity is frequently composed by intranet searching operations characterized by local queries that aim to explore documents stored in a neighbor of the home site. We study benefits from a channel allocation strategy applied to intranet searching with semantic caching. Simulation experiments are carried out by considering an indoor scenario model where mobile clients perform keyword-based queries answered by local Web servers running application we refer to as WISH (Wireless Intranet SearcHing), an intranet searching tool based on semantic caching. The results show a 12% improvement in radio channel usage for 20% of users that share cached documents. View full abstract»

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  • An analysis of wideband direction-of-arrival estimation for closely-spaced sources in the presence of array model errors

    Page(s): 314 - 316
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    This letter presents an analysis of wideband direction-of-arrival (DOA) estimation for closely-spaced sources using arbitrary antenna array taking into account the effect of array model error, which is important issue in practical implementation. Based on this analysis, a new wideband DOA estimation method without array calibration is then developed to deal with the effects of array errors. The performance improvement of the proposed method in the presence of array errors is shown in simulation results. View full abstract»

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  • Site diversity against rain fading in LMDS systems

    Page(s): 317 - 319
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    Local Multipoint Distribution Services (LMDS) system is a fixed cellular radio based point-to-multipoint technology in the microwave band providing broadband services. These systems need very accurate network planning method because of the variable carrier-to-interference ratio (C/I) in the whole service area and high sensitivity for meteorological phenomena especially for precipitation. The effects of a moving rain cell over an LMDS system was analyzed and site diversity as one possible countermeasure technique is demonstrated. The location dependent C/I in the LMDS service area under rainy conditions with and without site diversity technique was calculated applying a rain shower profile. View full abstract»

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  • Code sectoring methods in CDMA-based broadband point-to-multipoint networks

    Page(s): 320 - 322
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (378 KB) |  | HTML iconHTML  

    Code sectoring methods in broadband wireless point-to-multipoint (PMP) networks applying code-division multiple access (CDMA) are discussed in this paper. Interference reduction is the key factor in PMP network design, therefore antenna- and frequency-sectoring solutions are commonly applied. CDMA allows code sectoring strategies, moreover advanced interference suppression techniques (e.g., multiuser detection) can be utilized. The combination of different sectoring schemes and multiuser receivers in a CDMA-based PMP network provides the effective control of interference. In this study different CDMA code sectoring approaches are proposed and downlink interference analyses of a PMP network sector are presented. View full abstract»

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  • The implementation of channel diversity in mobile software radio receivers

    Page(s): 323 - 325
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    A novel channel diversity concept is proposed and demonstrated, which avoids receiving signal deterioration due to multipath fading in mobile receivers. The system is based on coherent superposition of the signals received from several transmitters supplying the same information at different frequencies. Based on a software radio architecture this concept may increase the quality of mobile reception in modern car receivers considerably. Compared with multiantenna-receivers which overcome the multipath fading problem by simultaneously receiving the same program with several antennas, the proposed solution is advantageous, since it requires only a single antenna. View full abstract»

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  • A wireless data link for mobile applications

    Page(s): 326 - 328
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    A short overview is given on wireless high speed data links for local-area-ad-hoc-networks in mobile applications and a multifunctional CDMA-Direct-Sequence Spread-Spectrum communicating platform is investigated which may be used for inter vehicle communication as well as for object detection and ranging in the environment of cars. View full abstract»

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  • Low phase-noise integrated voltage controlled oscillator design using LTCC technology

    Page(s): 329 - 331
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    This paper describes the design and implementation of a highly integrated voltage controlled oscillator (VCO) module based upon Low-Temperature Co-fired Ceramic (LTCC) packaging technology. The circuit is realized by embedding the strip-line resonator and lumped passives inside a multilayer LTCC substrate. Measurement results of a silicon bipolar VCO circuit operating at 2.4 GHz is shown. The constructed module is compact in size and has good phase noise performance. View full abstract»

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  • 40 Gb/s differential traveling wave modulator driver

    Page(s): 332 - 334
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    In this letter a MMIC differential traveling wave driver for 40 Gb/s electro-absorption modulation driver is presented. The driver delivers 2.7 Vp-p or 2.4 V eye amplitude at each output into 50 /spl Omega/ load. The driver has high gain (>20 dB), a 3 dB bandwidth of 45 GHz, and rise/fall times of only 10/9 ps, respectively. The circuit uses a single -5.0 V power supply and consumes 1.8 W of dc power. The driver also features cross-point control and output amplitude control functions. View full abstract»

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  • Resonator size effects on the TFBAR ladder filter performance

    Page(s): 335 - 337
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    Thin-film bulk acoustic resonators with different resonator sizes are simulated and measured. Their effects on ladder filter performance are also presented. Aluminum nitride and platinum are used as piezoelectric material and electrodes, respectively. As the shunt resonator size increases, out-of-band rejection performance has been improved. The 3/2 stage filters that have twice or three times larger resonators reveal 6 dB and 11 dB out-of-band rejection improvements, respectively. View full abstract»

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  • An integrated LTCC laminated waveguide-to-microstrip line T-junction

    Page(s): 338 - 339
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    In this paper, an integrated low-temperature co-fired ceramic (LTCC) laminated waveguide to microstrip line T-junction is proposed and experimentally verified. A multilayer bell-shape probe end comprising multiple parallel metallic pads is used to improve the bandwidth and matching condition. The experimental result shows good correlation with the simulated result. The configuration can also be used as the transition between microstrip line and laminated waveguide. View full abstract»

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  • Digital filtering technique for the FDTD implementation of the anisotropic perfectly matched layer

    Page(s): 340 - 342
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (290 KB) |  | HTML iconHTML  

    A new algorithm is presented for the finite difference time domain (FDTD) implementation of the anisotropic perfectly matched layer (PML) using the digital signal processing. The algorithm is based on modeling the anisotropic PML region as a set of infinite-impulse response (IIR) digital filters. The advantage of the proposed method is that it allows direct FDTD implementation of Maxwell's equations in the PML region. In addition, the formulations are implemented using D and B fields rather than E and H, and this allows the PML to be independent from the material properties of the FDTD computational domains. Numerical tests have been carried out in two dimensions to validate the formulations. View full abstract»

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  • Compressed-width leaky EH1 mode PBG antenna

    Page(s): 343 - 344
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    The recently developed electric-magnetic-electric (EME) microstrip is successfully used to design a compact leaky-mode antenna with fan beam radiation patterns. The EME microstrip consists of composite metals paralleling the electric and magnetic surfaces, where the magnetic surface is made of an array of coupled inductors. The frequency scanning behavior, experimentally and theoretically confirmed by matrix-pencil analyses, indicates that the line width can be reduced by 20%, compared to that of the conventional microstrip with the identical radiation angle of the first higher order (EH/sub 1/) mode at the same frequency. View full abstract»

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  • Extension and validation of a perfectly matched layer formulation for the unconditionally stable D-H FDTD method

    Page(s): 345 - 347
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    In this letter, a modification to the recently proposed unconditionally stable D-H ADI FDTD method is presented that considerably reduces the late-time error induced by the corner cells. The PML boundary is derived from the direct discretization of the modified D-H Maxwell's equations rather than the superposition of uniaxial PML boundaries. An optimal choice of the PML conductivity profile coefficients is proposed. Results show that the reflection error of the PML is limited for increased time step size beyond the Courant-Friedrichs-Lewy stability bound, and maximum reflection errors are 15 to 20 dB lower than the original formulation. View full abstract»

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  • An unsplit formulation of the Berenger's PML absorbing boundary condition for FDTD meshes

    Page(s): 348 - 350
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    An unsplit formulation of the Berenger's perfectly matched layer absorbing boundary condition (PML ABC) for finite-difference time-domain (FDTD) meshes is presented. This unsplit formulation uses the conventional E-H algorithm, but does not require the E and H fields to be split. The proposed formulation is memory-efficient like that of the previous unsplit PML following the theory of Sacks. This unsplit formulation is easy to be implemented, and many useful modification to the Berenger's PML can also be done to it. View full abstract»

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  • Unified method for determining the complex propagation constant of reflecting and nonreflecting transmission lines

    Page(s): 351 - 353
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    In this letter, a unified method for computing the complex propagation constant /spl gamma/ of reflecting and nonreflecting lines is presented. The method uses a new matrix representation of the wave cascade matrix of a line having any characteristic impedance. To overcome the sign ambiguity problem inherent to the classical method some parameters of the fictitious X/sub AM/ matrix are used and determined by the method itself. The success of the new procedure to resolve the sign ambiguity problem lies in the new matrix representation of the wave cascade matrix of a line having any characteristic impedance and in the reliable criterion to determine the a/sub m//c/sub m/ and b/sub m/ parameters of the fictitious X/sub AM/ matrix. View full abstract»

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  • Analysis of sharp metal edge diagonal to the cell cube in FDTD grid

    Page(s): 354 - 356
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    The finite-difference time-domain(FDTD) update equations for sharp metal edges are extended in this paper. New FDTD update equations for sharp metal edges diagonal to cell cube in FDTD grid are presented. Unlike the literature , the edge is assumed to be not parallel to any cell face. A dramatic improvement in computed accuracy was observed when a stripline with two sharp edges diagonal to the cell cube in FDTD grid was analyzed using the new equations. View full abstract»

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  • Proposal of a new folded comb-line filter

    Page(s): 357 - 359
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    We propose a new type of comb-line filter that is suitable for miniaturization utilizing stratifying technology. It consists of a couple of composite resonators. Each resonator is composed of two sections of a microstrip and a coplanar waveguide fabricated on the microstrip ground plane which are connected through a piece of wire at an open end to set up a new folded comb-line filter. The filtering characteristics are investigated through experiments as well as numerical simulations by means of the FD-TD method. It is shown that the filtering characteristics can be much improved by removing part of the barrier in the coplanar-line portion of the resonator to alter the coupling. View full abstract»

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Aims & Scope

The IEEE Microwave and Wireless Components Letters (MWCL) publishes three page papers that focus on microwave theory, techniques and applications as they relate to components, devices, circuits, biological effects, and systems involving the generation, modulation, demodulation, control, transmission, and detection of microwave signals.

Full Aims & Scope