Microwave Oscillator Phase Noise Requirement for TD-SCDM A Wireless Communication Systems

In time division synchronous code division multiple access （TD-SCDMA） wireless communication systems, QPSK or 8PSK has been employed to support high data rate services and high efficiency in available bandwidth. The performance of such systems is affected by the phase noise of the microwave local oscillator. The phase noise model of synthesizer and the RF transceiver model for the phase noise effect are proposed for applications of TD-SCDMA systems. The relationship between the power spectral density （PSD） and root mean square （RMS） phase error is given. Then, the error vector magnitude （EVM） performance is analytically evaluated by using the single side band （SSB） phase noise. Theoretical results show agreement with those obtained by measurement data and therefore can be used to derive the TD-SCDMA system performance.     

Compact CMOS Baluns for the 4–10 GHz Band Applications

In this paper, we proposed two baluns, a compact balun and a compact balun with imbalance compensation; both are implemented using the one-poly six-metal (1P6M) 0.18 μ m CMOS process. Both baluns have good performance from 4 to 10 GHz, and consume less silicon area due to their compact structure. The self-resonant frequency is increased by properly selecting metal layer for each spiral winding. The compact balun has a magnitude imbalance of 1 dB and a phase imbalance of 4.6 degree from 4 to 10 GHz. With the imbalance compensation, the balun has a magnitude imbalance of 0.6 dB and a phase imbalance of 1.1 degree from 4–10 GHz. Much better results have been achieved for the compact balun with our proposed imbalance compensation method. Both baluns can be used to perform both single-ended/differential and differential/single-ended conversions in different configurations.     

Research on the Handover of a Novel Cellular Architecture in Wireless Personal Communication Systems

1　IntroductionHandoverbetweencellsisplayinganimportantroleincellularcommunicationsystems[1～ 1 2 ] .Thehandoverprocedureanditseffectivenessareseriouslylimitedbythecellulararchitectureasaresultofmar ketplanning .Basedonthehexagonalcellulararchi tecture,manyhandoverprocedureshavebeendis cussedandevaluated ,andmostoftheimprovementproposedonthemleadstotheintroductionofsector ingcellularorlayeredcellularmodel.Otherwise ,abetterhandoverprocedureisessentialinmaintainingacallinprogressbutitreflectshi…     

A Methodology for Bit Error Rate Prediction in Chaos-based Communication Systems

This paper is devoted to the derivation of an exact analytical expression of the bit error rate for chaos-based DS-CDMA systems. For the studied transmission system, we suppose that synchronization is achieved perfectly, coherent reception is considered, and an Additive White Gaussian Noise channel (AWGN) is assumed. In the first part of the paper, performance of a mono-user system with different chaotic sequences is evaluated and compared in terms of the error probability. This comparison is realized thanks to the probability density function of the bit energy of a chaotic sequence. The bit error rate can be easily derived by numerical integration. In some particular cases, for certain chaotic sequences with known probability density function of bit energy, we propose an analytical expression of the bit error. In the second part of the paper, the performance of a chaos-based DS-CDMA system is evaluated in the multi-user case. A general conclusion is that probability density function of chaos bit energy, for a given spreading factor, can give a clear idea about how to choose a “good” chaotic sequence for improving the performance of the chaos-based CDMA system.     

Compact Efficient Feed-Horn at 30–38 GHz for a Multi-beam Radio Telescope

The requirements for a feed suitable for a radio telescope multi-beam focal plane array are considered. A smooth-walled spline-profile horn covering the 30–38 GHz frequency band to be used in a multi-beam receiving array of a radio telescope has been optimized, manufactured and tested. The achieved cross-section aperture size of the horn allows us to provide a neighboring beam spacing equal or less than 2HPBW for the RATAN-600 radio telescope. The measured sidelobe levels of the radiation pattern is less than −30dB/−24dB/−26dB in H/E/45⁰-planes, cross-polarization levels better than −20 dB, an input return loss better than −18 dB and the −3dB/−10dB-beamwidths are of the order of 40o/ 80o over the frequency band. Mutual-coupling of adjacent horns is less than −38 dB.     

Joint Downlink Scheduling and Radio Resource Allocation for User-Individual QoS in Adaptive OFDMA Wireless Communication Systems

1Introduction Futurewirelessandmobilecommunicationsystems areexpectedtoofferhigherdatarates,tosupporta largenumberofsubscribersandtoensurethefulfillment ofQualityofService(QoS)requirements,giventhe limitedavailabilityoffrequencyspectrumandtimevary ingchan…     

H ∞ Control with Limited Communication for Networked Control Systems

In this paper, the H _∞ control problem is studied for discrete time systems with limited communication network. The communication limitation includes signal quantization, random packet loss, which appear typically in a network environment. The random packet loss is modeled as a two-state Markov chain. Both the packet-loss dependent and independent H _∞ controllers are designed. The packet-loss dependent controller is applicable only to the network with accessible packet-loss information. However, the packet-loss independent controller is applicable to networks both with and without accessible packet-loss information. Finally, an example is provided to demonstrate the effectiveness and applicability of the proposed design approach.     

Batch Private Keys Generation for RSA in Security Communication Systems

RSA public key cryptosystem is extensively used in information security systems.However, key generation for RSA cryptosystem requires multiplicative inversion over finite field, which has higher computational complexity, compared with either multiplication in common sense or modular multiplication over fnite field. In order to improve the performance of key generation, we propose a batch private keys generation method in this paper. The method derives efficiency from cutting down multiplicative inversions over finite field. Theoretical analysis shows that the speed of batch private keys generation for s users is faster than that of s times solo private key generation. It is suitable for applications in those systems with large amount of users.     

Design of 95 GHz, 2 MW Gyrotron for Communication and Security Applications

The design and the numerical simulation of the 95 GHz, 2 MW gyrotron for various kinds of communication, sensing and security applications is presented. The gyrotron is designed for the TE_24,8 operating mode. Various in-house developed and commercially available computer codes are used for the design purpose. A 4.25 MW electron gun is designed for the 2 MW of output power. The mode selection, cold cavity and the beam–wave interaction analysis are discussed for the design of weakly tapered open resonator type of interaction cavity. The parametric analysis of the interaction cavity and the electron gun is also presented.     

Performance of Layered Steered Space–Time Codes in Wireless Systems

Layered Steered Space–Time Codes (LSSTC) is a recently proposed multiple-input multiple-output (MIMO) system that combines the benefits of vertical Bell Labs space–time (VBLAST) scheme, space–time block codes (STBC) and beamforming. In this paper, we derive the error performance and capacity of a single-user LSSTC system. The analysis is general enough to any layer ordering and modulation schemes used. In addition, the derived analysis is general for any LSSTC structure in which layers may have different number of antenna arrays and may be assigned power according to any power allocation. Furthermore, we analytically investigate the tradeoff between the main parameters of the LSSTC system, i.e., diversity, multiplexing and beamforming. Our results give recursive expressions for the probability of error for LSSTC which showed nearly perfect match to the simulation results. Results have also revealed the possibility of designing an adaptive system in which it was shown that combining beamforming, STBC, and VBLAST has better performance than VBLAST at high SNR range.     

Signal Processing by Generalized Receiver in?DS-CDMA Wireless Communication Systems with?Frequency-Selective Channels

The generalized receiver (GR) based on a generalized approach to signal processing (GASP) in noise is investigated in a direct-sequence code-division multiple access (DS-CDMA) wireless communication system with frequency-selective channels. We consider four avenues: linear equalization with finite impulse response (FIR) beamforming filters; channel estimation and spatially correlation; optimal combining; and partial cancellation. We investigate the GR with simple linear equalization and FIR beamforming filters. Numerical results and simulation show that the GR with FIR beamforming filters surpasses in performance the optimum infinite impulse response beamforming filters with conventional receivers, and can closely approach the performance of GR with infinite impulse response beamforming filters. Channel estimation errors are taken into consideration so that DS-CDMA wireless communication system performance will not be degraded under practical channel estimation. GR takes an estimation error of a maximum likelihood (ML) multiple-input multiple-output (MIMO) channel estimation and GR spatially correlation into account in computation of minimum mean square error (MMSE) and log-likelihood ratio (LLR) of each coded bit. The symbol error rate (SER) performance of DS-CDMA employing GR with a quadrature sub-branch hybrid selection/maximal-ratio combining (HS/MRC) scheme for 1-D modulations in Rayleigh fading is obtained and compared with that of conventional HS/MRC receivers. Procedure of selecting a partial cancelation factor (PCF) for the first stage of a hard-decision partial parallel interference cancellation (PPIC) of the GR employed in DS-CDMA wireless communication system is proposed. A range of optimal PCFs is derived based on the Price’s theorem. Computer simulation results show superiority in bit error rate (BER) performance that is very close to that potentially achieved and surpasses the BER performance of the real PCF for DS-CDMA systems discussed in literature.     

Development of a Submillimeter Double-Ridged Waveguide Ortho-Mode Transducer (OMT) for the 385–500 GHz Band

We present design and evaluations of a submillimeter double-ridged waveguide ortho-mode transducer (OMT) for ALMA Band 8 (385–500 GHz) cartridge receiver. The measured transmission loss of the OMT at 4 K was 0.4–0.5 dB according to noise measurements with an SIS mixer. The polarization isolation was measured to be larger than 29 dB from quasioptical measurements. The OMT consists of a Bϕifot junction and a double-ridged guide. A robust design with allowable mechanical errors of 20 μm has been demonstrated.     

Model Scenarios for Direction-Selective Adaptive Antennas in Cellular Mobile Communication Systems – Scanning the Literature

Intelligent antennas offer the possibility of greatly increasing the capacity of cellular mobile radio systems. We give a comprehensive overview of the literature concerning model scenarios for applications of direction-selective intelligent antennas. Measurement campaigns and simplified models are described that have been derived from these measurements or from physical considerations. Furthermore, directional fading simulators are reviewed which are essential for testing of smart antenna systems.     

New CRLH-Based Planar Slotted Antennas with Helical Inductors for Wireless Communication Systems,RF-Circuits and Microwave Devices at UHF–SHF Bands

Two novel planar slotted-antennas (PSAs) are presented that exhibit good radiation characteristics at the UHF–SHF bands. The proposed antennas are constructed using metamaterial unit-cells constituted from capacitive slots etched in the radiating patch and grounded spiral shaped inductive stubs. The proposed PSA design is fabricated on a commercially available dielectric substrate, i.e. Rogers RO4003 with permittivity of 3.38 and thickness of 1.6 mm. The first PSA comprising five symmetrical unit-cells of slot–inductor–slot configuration operates over a wide bandwidth extending from 1 to 4.2 GHz with a peak gain of 1.5 dBi and efficiency of 35 % at 2 GHz. The second PSA consists of ten asymmetrical unit-cells of slot–inductor configuration on the same size of substrate as the first PSA, enhances the antenna gain by 2 dB and efficiency by 25 % and operates over 0.75–4.5 GHz. The asymmetrical unit-cell effectively increases the aperture size of the antenna without comprising its size. The electrical size of the antenna is 0.083λ₀ × 0.033λ₀ × 0.005λ₀, where free-space wavelength (λ₀) is 1 GHz.     

Compact,Isolation Enhanced,Band-Notched SWB–MIMO Antenna Suited for Wireless Personal Communications

Herein, a Conductor Backed Co-Planar Waveguide fed, compact, slotted Multiple–Input–Multiple–Output or MIMO antenna having Super Wideband (SWB) response and tunable band-notching feature is presented. In addition, an improved method for cut-off frequency prediction of the antenna is formulated. A super wide frequency response from 01.21 to 34.0 GHz and notches at Wireless Local Area Networks or WLAN bands (04.92–05.83 GHz) and Worldwide Inter-operability for Microwave Access or WiMAX bands (03.30 GHz–03.70 GHz) are obtained. By fine tuning the dimensions of the Split Ring Resonator Structure introduced in the radiating element, band-notched characteristics centered at 05.50 GHz WLAN band is obtained. A second band notch having centre frequency at 03.50 GHz for the WiMAX band is obtained by the introduction of a Spiral Microstrip Defected Structure in the feeding segment. The antenna is 20?×?36?×?1 mm³ in dimension. Acceptable gain all through the functional bandwidth, excepting the notched bands makes the MIMO antenna a novel contender for SWB operations particularly for Wireless Personal Communications.

     

A 1 V power amplifier for 81–86 GHz E-band

The design and layout of a two stage SiGe E-band power amplifier using a stacked transformer for output power combination is presented. In EM-simulations with ADS Momentum, at E-band frequencies, the power combiner consisting of two individual single turn transformers performs significantly better than a single 2:1 transformer with two turns on the secondary side. Imbalances in the stacked transformer structure are reduced with tuning capacitors for maximum gain and output power. At 84 GHz the simulated loss of the stacked transformer is as low as 1.35 dB, superseding the performance of an also presented alternative power combiner. The power combination allows for a low supply voltage of 1 V, which is beneficial since the supply can then be shared between the power amplifier and the transceiver, thereby eliminating the need of a separate voltage regulator. To improve the gain of the two-stage amplifier it employs a capacitive cross-coupling technique not yet seen in mm-wave SiGe PAs. Capacitive cross-coupling is an effective technique for gain enhancement but is also sensitive to process variations as shown by Monte Carlo simulations. To mitigate this two alternative designs are presented with the cross coupling capacitors implemented either with diode coupled transistors or with varactors. The PA is designed in a SiGe process with f _T  = 200 GHz and achieves a power gain of 12 dB, a saturated output power of 16 dBm and a 14 % peak PAE. Excluding decoupling capacitors it occupies a die area of 0.034 mm².     

Indoor Radio Propagation and Interference in 2.4 GHz Wireless Sensor Networks: Measurements and Analysis

In wireless sensor networks (WSNs), the performance and lifetime are significantly affected by the indoor propagation and the interference from other technologies using the 2.4 GHz band. Next to an overview of the propagation and coexistence issues in the literature, we present a model for analysing these effects in WSNs. We also present our measurements results on the indoor propagation, the interference of the microwave oven (MWO) and their impact on the performance of the WSN. The propagation measurements reveal significant influence of the multipath: changing a node position with a few centimetres or changing the communication channel can lead up to 30 dB difference in the received power. The power leakage of MWO has been observed around $-$ 20 dBm at 1 m distances to the oven. This leads to extra retries of the 802.15.4 messages which matches our simulation results: the packet success ratio at first try decreases to 30–40 %, which increases the average active time of the sensor, closely located to the MWO. We observe that the ON–OFF pattern of the MWO could be exploited by WSNs to improve the performance.     

Multiuser Detection in SDMA–OFDM Wireless Communication System Using Complex Multilayer Perceptron Neural Network

The space division multiple access–orthogonal frequency division multiplexing (SDMA–OFDM) wireless system has become very popular owing high spectral efficiency and high load capability. The optimal maximum likelihood multiuser detection (MUD) technique suffers from high computational complexity. On the other hand the linear minimum mean square error (MMSE) MUD techniques yields poor performance and also fails to detect users in overload scenario, where the number of users are more than that of number of receiving antennas. By contrast, the differential evolution algorithm (DEA) aided minimum symbol error rate (MSER) MUD can sustain in overload scenario as it can directly minimizes probability of error rather than mean square error. However, all these classical techniques are still complex as these do channel estimation and multiuser detection sequentially. In this paper, complex multi layer perceptron (CMLP) neural network model is suggested for MUD in SDMA–OFDM system as it do both channel approximation and MUD simultaneously. Simulation results prove that the CMLP aided MUD performs better than the MMSE and MSER techniques in terms of enhanced bit error rate performance with low computational complexity.     

Optimization of the UTC-PD Epitaxy for Photomixing at 340 GHz

We present a method to optimize the epitaxial layer structure of an InGaAs/InP uni-traveling-carrier photo-diode (UTC-PD) for continuous THz-wave generation. The design approach used is general in that it can be applied for any target frequency while this study focuses on 340 GHz. The photodiode epitaxy is modeled and optimized using a TCAD software implementing the hydrodynamic semiconductor equations. This physical device model was found to be in good agreement with reported experimental results. It is shown that the UTC-PD can generate ~1 mW at 340 GHz by choosing the optimum absorption layer and collection layer thicknesses.