Subblock processing in MMSE-FDE under fast fading environments

Frequency domain equalization (FDE) has been studied for reducing inter-symbol interference (ISI) caused by frequency selective fading in single carrier systems. When a high-mobility terminal exists in the system, the channel state may change within a DFT block. Then, the ISI reduction performance of FDE degrades since cyclicity of the channel matrix is lost. We propose to divide a received data block into multiple subblocks to decrease the channel transition within the DFT block in fast fading environments. Also, to satisfy periodicity of the received signal in each subblock, we introduce a pseudo cyclic prefix technique. The results of numerical analysis show that the proposed method can effectively decrease the error floor in fast fading environments.     

Metathesis copolymerization of chlorine-containing acetylenes with NBE catalyzed by MoCl5-n-Bu4Sn

Summary In the copolymerizations of 1-chloro-1-octyne (ClOc) and 1-chloro-2-phenylacetylene (ClPA) with norbornene (NBE) by MoCl₅-n-Bu₄Sn in toluene at-20°C, both comonomers were consumed simultaneously. The GPC curves of the copolymerization products were unimodal and identical irrespective of the RI and UV (290 nm) detectors. The¹³C NMR spectra of the products exhibited the presence of cross-propagating sequences. From these results, it is concluded that the copolymerization products are copolymers and not mixtures of homopolymers. The monomer reactivity ratios were: r_ClOc=0.69, r_NBE=6.4; r_ClPA=1.0, r_NBE=3.1. The more electron-donating the ring substituent of CiPA, the more reactive the ClPA in copolymerization with NBE.     

An implementation of a CMA adaptive array for high speed GMSKtransmission in mobile communications

The hardware implementation of an adaptive array as a technique for compensating multipath fading in mobile communications is described. The number of the antenna elements is four. The target communication system is modulated by 256 kbps Gaussian-filtered minimum shift keying (MSK) and has a time-division multiplexing (TDM) architecture with 24 time slots. Based on the digital beamforming concept, all of the signals and the array weights are digital-signal processed. The constant modulus algorithm (CMA) is employed for weight optimizing. In an additive white Gaussian noise channel, this system has 5.6-dB gain in an energy-per-bit-to-noise-density ratio at a bit error rate (BER) of 1.0×10^-3, compared with a single antenna system. The result of the basic field test shows that the gain at a BER of 1.0×10^-3 reaches 22.3 dB in a nonselective, slow Rayleigh fading channel given a 5 Hz maximum Doppler shift     

Development of 12 T-10 Al-stabilized Nb3Sn conductor for TMC-II

The Al-stabilized Nb3Sn strand has been successfully fabricated and Jcvalue of 400 A/mm²at 12 T is obtained on condition that Nb3Sn is reacted at 625°C for 200 hr. Overall residual resistivity of this strand is lowered to 77 % of that of the Cu-stabilized Nb3Sn strand (TMC-I)^1,2at 12 T by Al-stabilizer. The 12 T-10 kA cable-in-conduit conductor, fabricated by this strands, is charged up to 20 kA at 8.7 T without appearance of normal zone. From these experimental results, this conductor satisfies almost the specification of the present target conductor (TMC-II)³.     

BER performance of CMA adaptive array for high-speed GMSK mobilecommunication-a description of measurements in central Tokyo

This paper describes the performance of an adaptive array as a countermeasure to multipath fading for a 256 kbps Gaussian-filtered minimum shift keying (GMSK) mobile communication system operating in the 1.5 GHz band. An adaptive array having four antenna elements is implemented using the digital beam forming concept. The constant modulus algorithm (CMA) is employed for the adaptation process to ease the implementation. Measurements in central Tokyo of the bit error rate (BER) performance and an array pattern arising in the multipath environment are presented. Analysis of the array pattern confirms that the array succeeds in directing nulls to the delayed signals. BER performance shows an improvement in E_b/N₀, compared with that of a single antenna system, of 17.5 to 22 dB at a BER of 1.0×10^-2 in a frequency-selective fading channel