B. Stantchev

Technische Universität Dresden, Dresden, Saxony, Germany

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Publications (11)1.16 Total impact

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    Branimir Stantchev, Gerhard Fettweis
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    ABSTRACT: In thispaper an optimum and sub-optimum maximum likelihood (ML) rule for joint frame and carrier frequency o#set estimation are derived, which rely on the transmission of a periodic pattern signal with an arbitrary number of periods and period length, embedded in the random data signal of a single user. Ad-hoc modification of the ML rule yields a robust metric for pattern search in a multi-user signal in a time division multiple access and time division duplex (TDMA/TDD) system, and a receiver with automatic gain control keeping constant average signal power at the synchronizer input. The mean, variance and Cramer-Rao Bound of the frequency o#set estimate as well as the mean and variance of the frame estimate are theoretically evaluated and verified by simulation. The presented material proposes a unified framework for synchronization by periodic pattern signals and provides some new results, which are compared to known references.
    04/2002;
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    ABSTRACT: The paper presents a wireless integrated services communications system for indoor and campus use. Whereas most current indoor wireless systems are distinct solutions for different services, our network, WISCS, covers the entire range from low-rate mobiles to high-speed portables. The system employs a picocellular structure in the 60 GHz band to provide capacity demanded by broadband services. The system concept and the employment of simple transponders connected via an optical fibre to a central base station allow a cost effective implementation. Virtual clustering of different number of cells is applied to allow coexistance of low rate mobile users and high rate portable users in one common system. WISCS uses adaptive modulation to yield an optimised performance in both the mobile and portable environment. The project is carried out at Communications Laboratory at Dresden University of Technology. Research includes new optical devices, flexible, efficient and error protected transmitting schemes, mm-wave circuits, antennas, and protocols. A demonstrator is currently under development.
    04/2002;
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    Branimir Stantchev, Gerhard Fettweis
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    ABSTRACT: The design of a broadband cellular network demands powerful modulation and coding under the tight constraints of affordable modem complexity and low power consumption for the mobile terminal (MT). In order to increase battery life and allow low-cost mobile equipment to be effectively integrated in such a broadband system we propose the use of a low-rate separate signaling channel (SSC) on the physical layer. It has the primary function of power saving and takes on connectivity and mobility control functions as well as synchronization tasks. A new concept of a broadband OFDM-based FTDMA system is presented, incorporating a high rate physical data channel (D-channel) and a SSC. One application of such a concept can be a cellular ATM access network with a dynamic channel allocation wireless MAC protocol. Modem and system design issues are discussed and evaluated by simulation. A new method for calculating the output backoff (OBO) of a power amplifier for an OFDM signal is presented.
    04/2002;
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    Branimir Stantchev, Jens Voigt, Volker Aue, Gerhard P. Fettweis
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    ABSTRACT: In this paper the air interface for an integrated broadband wireless system at 60 GHz is introduced. The system is targeted for accommodating di#erent multimedia services such as voice, video, and high data rates up to 155 Mbit#s ATM at low cost and to allow for some mobility. The paper discusses the di#culties of designing a multiple access scheme and choosing the right modulation techniques for such an integrated system. It is shown that due to the heterogeneity of the di#erent demands regarding bit rate, bit error rate, burstiness, cost, and mobility, amodular system structureisneeded. After the general problem statement of the basic properties and demands, a solution for the air-interface at 60 GHz is derived.
    04/2002;
  • Source
    Branimir Stantchev, Gerhard Fettweis
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    ABSTRACT: We derive a maximum likelihood (ML) rule for one-shot frame synchronization of a random data burst with non-coherent orthogonal M-FSK signaling in a flat fading or AWGN channel. It uses a known frame synchronization pattern and, optionally, channel state information at the receiver. High SNR approximations are developed that are well suited for a low-cost implementation. A burst synchronizer structure is proposed with an ML frame synchronizer as the last processing stage. Simulations reveal the performance gain of the ML rules over conventional correlation rules for a 2-CPFSK modulated separate signaling channel in an OFDM FTDMA broadband cellular system.
    04/2002;
  • B. Stantchev, G. Fettweis
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    ABSTRACT: We analyze the degradation of orthogonal frequency division multiplexing (OFDM) signals from time-variant distortions like carrier and sampling frequency offset, Doppler spread and oscillator phase noise. We propose a novel analytical framework in the discrete-time domain based on the FFT demodulation of a single OFDM symbol and unify previous methods with some new results. Exact definitions of the signal-to-subcarrier-interference ratio (SIR) and the effective signal-to-noise ratio (SNR) are given and evaluated for a HIPERLAN/2 system.
    IEEE Communications Letters 11/2000; · 1.16 Impact Factor
  • Branimir Stantchev, Gerhard Fettweis
    IEEE Communications Letters. 01/2000; 4:312-314.
  • Source
    B. Stantchev, G. Fettweis
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    ABSTRACT: We derive a maximum likelihood (ML) rule for one-shot frame synchronization of a random data burst with non-coherent orthogonal M-FSK signaling in a flat fading or AWGN channel. It uses a known frame synchronization pattern and, optionally, channel state information at the receiver. High SNR approximations are developed that are well suited for a low-cost implementation. A burst synchronizer structure is proposed with an ML frame synchronizer as the last processing stage. Simulations reveal the performance gain of the ML rules over conventional correlation rules for a 2-CPFSK modulated separate signaling channel in an OFDM FTDMA broadband cellular system
    Wireless Communications and Networking Conference, 1999. WCNC. 1999 IEEE; 02/1999
  • Source
    B. Stantchev, G. Fettweis
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    ABSTRACT: A novel burst synchronization scheme suitable for a high rate OFDM/TDMA/TDD (pico)cellular system with a centralized dynamic slot allocation MAC protocol is presented. The physical layer may have an optional low-rate separate signaling channel (SSC) used in the standby mode and implemented on a subset of OFDM subcarriers. A one-shot feedforward synchronization concept for the OFDM-based active transmission mode is designed using the functionality of the SSC and a special periodical OFDM preamble. Joint symbol and frequency synchronization as well as channel estimation can be achieved simultaneously. The synchronizer features low complexity and low processing delay. Simulations verify its robust operation for indoor channel power delay profiles at 5 GHz
    Vehicular Technology Conference, 1998. VTC 98. 48th IEEE; 06/1998
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    B. Stantchev, J. Kuehne, M. Bronzel, G. Fettweis
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    ABSTRACT: Future broadband picocellular networks demand powerful modulation and coding methods under the tight constraints of affordable modem complexity and low power consumption for the mobile terminal (MT). In order to increase battery life and allow low-cost mobile equipment to be effectively integrated in such a broadband system we propose the use of a separate low-rate signaling channel (SSC) on the physical layer. This additional channel has the primary function of power saving. For this purpose it takes on connection and mobility control functions as well as further tasks on broadcasting and synchronization. A new concept of a broadband TDMA system is presented, incorporating OFDM for the physical high rate data channel (D-channel) and CPFSK modulation with non-coherent detection for the low-rate SSC, whereby both channels are separated in frequency. Modem and system design issues are discussed and evaluated by simulation
    Vehicular Technology Conference, 1997, IEEE 47th; 06/1997
  • B. Stantchev, J. Voigt, V. Aue, G. P. Fettweis
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    ABSTRACT: In the framework of the Innovationskolleg “Kommunikationssysteme” sponsored by the German research foundation (DFG) an integrated broadband wireless system at 60 GHz is developed. The system is targeted for accomodating different multimedia services such as voice, video, and high data rates up to 155 Mbit/s ATM at low cost and to allow for some mobility. This paper discusses the difficulties of designing a multiple access scheme and choosing the right modulation techniques for such an integrated system. It is shown that due to the heterogeneity of the different demands of bit rate, bit error rate, burstiness, cost, and mobility, a modular system structure is needed. After the general problem statement of the basic properties and demands, a solution for the air-interface at 60 GHz is derived.
    Wissenschaftliche Zeitschrift der Technischen Universität Dresden. 01/1997; 46(2):60-65.