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Excess delay spread detection method for multi-carrier communication systems

A communication unit and communication channel technology, applied in the field of communication systems, can solve problems such as high computational complexity

Inactive Publication Date: 2006-01-11
GOOGLE TECHNOLOGY HOLDINGS LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, for multi-carrier systems, the channel estimation process proposed by the prior art is computationally complex since it involves a Fast Fourier Transform ("FFT") followed by an Inverse Fast Fourier Transform ("IFFT") to extract channel impulse response

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  • Excess delay spread detection method for multi-carrier communication systems
  • Excess delay spread detection method for multi-carrier communication systems
  • Excess delay spread detection method for multi-carrier communication systems

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Embodiment Construction

[0018] Preferred embodiments of the present invention relate to multi-carrier communication systems, such as Orthogonal Frequency Division Multiplexing ("OFDM") and OFDM variants (e.g. Extended OFDM), and may also be used for other types of modulation using cyclic prefixes and / or suffixes method. An exemplary OFDM symbol 10 is illustrated in FIG. 1 with a cyclic prefix and a suffix. Further, the transmitter can use the prior art OFDM synchronization symbol format to transmit a signal with two identical segments, e.g. image 3 as explained in .

[0019] figure 2 Exemplary OFDM transmitter components are illustrated in the form of an IFFT 20 and a parallel-to-serial converter ("PSC") 21 for periodically generating synchronization symbols, as is known in the art. Synchronization symbols include known or unknown data symbols DS 1 -DS x A sequence of , which is sent on double-numbered OFDM subcarriers, also includes empty symbols NS 1 -NS x , which is sent on an unused singl...

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Abstract

A method for detecting a presence of an excess delay spread within a received signal (S42) is provided. First, a quantitative estimation (S44) of a similarity of two segments of the received signal is performed. Thereafter, the presence of the excess delay spread within the received signal based upon the quantitative estimation is determined. In determining the presence of an excess delay spread (S46) , the quantitative estimation can be compared to a detection threshold.

Description

technical field [0001] Generally, the present invention relates to the field of communication systems. More specifically, the present invention relates to methods for detecting the presence of excessive delay spread in a communication system. Background technique [0002] Orthogonal Frequency Division Multiplexing (OFDM) systems generally include a cyclic extension (or guard interval) in each transmitted OFDM symbol. Cyclic extension is intended to eliminate inter-symbol and inter-carrier interference in delay-spread channels. However, if the channel impulse response is longer than the cyclic extension, the portion of the impulse response outside the extension causes self-interference. [0003] Delay spread detection circuits exist in the prior art to estimate delay spread in radio frequency signals. Most existing delay-spread sensors are designed for single-carrier systems. For example, the prior art delay spread estimator disclosed in US Patent No. 5,602,484A1 detects ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04B1/02H03D7/00H04L25/02H04L27/26
CPCH04L1/0023H04L25/0216H04L27/2605H04L1/20H03D7/00H04B1/02H04L27/26
Inventor 桑迪普·穆克他瓦拉姆凯文·鲍姆托马斯·克劳斯
Owner GOOGLE TECHNOLOGY HOLDINGS LLC