Timing acquisition of frequency-hopped ultra-wideband OFDM system

Paavo Hahtola

Research output: ThesisMaster's thesisTheses

Abstract

In this thesis, the timing acquisition of a frequency-hopped (FH) ultra-wideband (UWB) orthogonal frequency division multiplexing (OFDM) system is studied. A scenario in which the time-frequency code (TFC) is deterministic but unknown to the receiver is addressed. Acquisition time and the training data overhead should be kept to a minimum. This makes timing acquisition in the FH system a challenging task. First, the FH-OFDM technique is presented and the stages in timing synchronization of a general wireless communication system are introduced. Existing methods for decision variable generation, detection of the presence of the signal, and determination of the TFC are reviewed. Signal design for synchronization and timing synchronization requirements are discussed. After presentation of the target system model’s characteristics, simulation goals and assumptions are specified and simulation results are provided and analyzed. First, simulations are run for an additive white Gaussian noise (AWGN) channel, and then the effects of a frequency-selective fading channel are studied. Data-aided methods for decision variable generation are addressed. Differential correlation is chosen as the basis for the timing acquisition scheme, due to its good tolerance for multipath fading and lower complexity. The probability of detecting the presence of the signal is simulated for different training symbol structures and parameters. A method for determining the TFC is developed, and its performance is simulated for different numbers of subbands and training symbols. The method uses an exclusionary strategy in which the initial list of possible TFCs is shortened iteratively on the basis of results from testing of different subbands for the presence of the signal. The simulation results indicate the detector parameters and preamble structure that are feasible for the target system. The results imply that the differential-correlation-based detector performs well in both AWGN and fading channels and that it is very reliable even at low signal-to-noise ratios (SNR), of 0–5 dB. The TFC determination method developed is demonstrated to be able to determine the correct TFC efficiently even from a set of 30–60 possible TFCs by using a relatively small number of training symbols. As a conclusion, it is suggested that a differential-correlation-based detector with correlation length equal to correlation distance and a search step size of ¼ or ½ symbols should be used. The preamble should contain a number of training symbols of at least twice the length of the TFC.
Original languageEnglish
QualificationMaster Degree
Awarding Institution
  • University of Oulu
Place of PublicationOulu
Publisher
Publication statusPublished - 2007
MoE publication typeG2 Master's thesis, polytechnic Master's thesis

Fingerprint

Ultra-wideband (UWB)
Orthogonal frequency division multiplexing
Synchronization
Detectors
Fading channels
Frequency selective fading
Multipath fading
Signal to noise ratio
Communication systems
Testing

Keywords

  • Synchronization: timing offset: differential correlation: training signal: multi-carrier modulation

Cite this

Hahtola, P. (2007). Timing acquisition of frequency-hopped ultra-wideband OFDM system. Oulu: University of Oulu.
Hahtola, Paavo. / Timing acquisition of frequency-hopped ultra-wideband OFDM system. Oulu : University of Oulu, 2007. 76 p.
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title = "Timing acquisition of frequency-hopped ultra-wideband OFDM system",
abstract = "In this thesis, the timing acquisition of a frequency-hopped (FH) ultra-wideband (UWB) orthogonal frequency division multiplexing (OFDM) system is studied. A scenario in which the time-frequency code (TFC) is deterministic but unknown to the receiver is addressed. Acquisition time and the training data overhead should be kept to a minimum. This makes timing acquisition in the FH system a challenging task. First, the FH-OFDM technique is presented and the stages in timing synchronization of a general wireless communication system are introduced. Existing methods for decision variable generation, detection of the presence of the signal, and determination of the TFC are reviewed. Signal design for synchronization and timing synchronization requirements are discussed. After presentation of the target system model’s characteristics, simulation goals and assumptions are specified and simulation results are provided and analyzed. First, simulations are run for an additive white Gaussian noise (AWGN) channel, and then the effects of a frequency-selective fading channel are studied. Data-aided methods for decision variable generation are addressed. Differential correlation is chosen as the basis for the timing acquisition scheme, due to its good tolerance for multipath fading and lower complexity. The probability of detecting the presence of the signal is simulated for different training symbol structures and parameters. A method for determining the TFC is developed, and its performance is simulated for different numbers of subbands and training symbols. The method uses an exclusionary strategy in which the initial list of possible TFCs is shortened iteratively on the basis of results from testing of different subbands for the presence of the signal. The simulation results indicate the detector parameters and preamble structure that are feasible for the target system. The results imply that the differential-correlation-based detector performs well in both AWGN and fading channels and that it is very reliable even at low signal-to-noise ratios (SNR), of 0–5 dB. The TFC determination method developed is demonstrated to be able to determine the correct TFC efficiently even from a set of 30–60 possible TFCs by using a relatively small number of training symbols. As a conclusion, it is suggested that a differential-correlation-based detector with correlation length equal to correlation distance and a search step size of ¼ or ½ symbols should be used. The preamble should contain a number of training symbols of at least twice the length of the TFC.",
keywords = "Synchronization: timing offset: differential correlation: training signal: multi-carrier modulation",
author = "Paavo Hahtola",
note = "CA2: TK703 OH: diplomity{\"o} Department of Electrical and Information Engineering: Degree Programme in Telecommunications PGN: 76",
year = "2007",
language = "English",
publisher = "University of Oulu",
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Hahtola, P 2007, 'Timing acquisition of frequency-hopped ultra-wideband OFDM system', Master Degree, University of Oulu, Oulu.

Timing acquisition of frequency-hopped ultra-wideband OFDM system. / Hahtola, Paavo.

Oulu : University of Oulu, 2007. 76 p.

Research output: ThesisMaster's thesisTheses

TY - THES

T1 - Timing acquisition of frequency-hopped ultra-wideband OFDM system

AU - Hahtola, Paavo

N1 - CA2: TK703 OH: diplomityö Department of Electrical and Information Engineering: Degree Programme in Telecommunications PGN: 76

PY - 2007

Y1 - 2007

N2 - In this thesis, the timing acquisition of a frequency-hopped (FH) ultra-wideband (UWB) orthogonal frequency division multiplexing (OFDM) system is studied. A scenario in which the time-frequency code (TFC) is deterministic but unknown to the receiver is addressed. Acquisition time and the training data overhead should be kept to a minimum. This makes timing acquisition in the FH system a challenging task. First, the FH-OFDM technique is presented and the stages in timing synchronization of a general wireless communication system are introduced. Existing methods for decision variable generation, detection of the presence of the signal, and determination of the TFC are reviewed. Signal design for synchronization and timing synchronization requirements are discussed. After presentation of the target system model’s characteristics, simulation goals and assumptions are specified and simulation results are provided and analyzed. First, simulations are run for an additive white Gaussian noise (AWGN) channel, and then the effects of a frequency-selective fading channel are studied. Data-aided methods for decision variable generation are addressed. Differential correlation is chosen as the basis for the timing acquisition scheme, due to its good tolerance for multipath fading and lower complexity. The probability of detecting the presence of the signal is simulated for different training symbol structures and parameters. A method for determining the TFC is developed, and its performance is simulated for different numbers of subbands and training symbols. The method uses an exclusionary strategy in which the initial list of possible TFCs is shortened iteratively on the basis of results from testing of different subbands for the presence of the signal. The simulation results indicate the detector parameters and preamble structure that are feasible for the target system. The results imply that the differential-correlation-based detector performs well in both AWGN and fading channels and that it is very reliable even at low signal-to-noise ratios (SNR), of 0–5 dB. The TFC determination method developed is demonstrated to be able to determine the correct TFC efficiently even from a set of 30–60 possible TFCs by using a relatively small number of training symbols. As a conclusion, it is suggested that a differential-correlation-based detector with correlation length equal to correlation distance and a search step size of ¼ or ½ symbols should be used. The preamble should contain a number of training symbols of at least twice the length of the TFC.

AB - In this thesis, the timing acquisition of a frequency-hopped (FH) ultra-wideband (UWB) orthogonal frequency division multiplexing (OFDM) system is studied. A scenario in which the time-frequency code (TFC) is deterministic but unknown to the receiver is addressed. Acquisition time and the training data overhead should be kept to a minimum. This makes timing acquisition in the FH system a challenging task. First, the FH-OFDM technique is presented and the stages in timing synchronization of a general wireless communication system are introduced. Existing methods for decision variable generation, detection of the presence of the signal, and determination of the TFC are reviewed. Signal design for synchronization and timing synchronization requirements are discussed. After presentation of the target system model’s characteristics, simulation goals and assumptions are specified and simulation results are provided and analyzed. First, simulations are run for an additive white Gaussian noise (AWGN) channel, and then the effects of a frequency-selective fading channel are studied. Data-aided methods for decision variable generation are addressed. Differential correlation is chosen as the basis for the timing acquisition scheme, due to its good tolerance for multipath fading and lower complexity. The probability of detecting the presence of the signal is simulated for different training symbol structures and parameters. A method for determining the TFC is developed, and its performance is simulated for different numbers of subbands and training symbols. The method uses an exclusionary strategy in which the initial list of possible TFCs is shortened iteratively on the basis of results from testing of different subbands for the presence of the signal. The simulation results indicate the detector parameters and preamble structure that are feasible for the target system. The results imply that the differential-correlation-based detector performs well in both AWGN and fading channels and that it is very reliable even at low signal-to-noise ratios (SNR), of 0–5 dB. The TFC determination method developed is demonstrated to be able to determine the correct TFC efficiently even from a set of 30–60 possible TFCs by using a relatively small number of training symbols. As a conclusion, it is suggested that a differential-correlation-based detector with correlation length equal to correlation distance and a search step size of ¼ or ½ symbols should be used. The preamble should contain a number of training symbols of at least twice the length of the TFC.

KW - Synchronization: timing offset: differential correlation: training signal: multi-carrier modulation

M3 - Master's thesis

PB - University of Oulu

CY - Oulu

ER -

Hahtola P. Timing acquisition of frequency-hopped ultra-wideband OFDM system. Oulu: University of Oulu, 2007. 76 p.