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Determination of active spreading codes and their powers

A spread spectrum code and power technology, applied in code division multiplexing systems, electrical components, transmission systems, etc., can solve the problems of reducing the performance of traditional receivers, achieve low runtime complexity, and improve the effect of runtime

Inactive Publication Date: 2009-03-04
TELEFON AB LM ERICSSON (PUBL)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These systems attempt to limit the near-far problem using power control
However, even a small amount of near-far effect can drastically degrade the performance of conventional receivers

Method used

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  • Determination of active spreading codes and their powers
  • Determination of active spreading codes and their powers
  • Determination of active spreading codes and their powers

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Embodiment Construction

[0039] Fig. 1 shows an Orthogonal Variable Spreading Factor (OVSF) used in the present invention for spreading code detection. As described above, spreading codes are used to increase the data rate of the transmitted signal by multiplying the data bits of the signal by a higher frequency spreading code to spread the spectrum of the transmitted signal. These spreading codes are formed from a code tree called an Orthogonal Variable Spreading Factor Tree, where all codes at a given spreading factor SF or at a certain level of the OVSF tree are orthogonal to each other. The use of OVSF codes enables various spreading codes of different lengths to be mutually orthogonal. Therefore, in the OVSF structure, multi-rates can be modeled as multi-codes.

[0040] figure 2 A typical communication system in which the present invention may be employed is shown. Here, a CDMA system includes a number of mobile or subscriber stations (MS 1 ,…, MS K ), which allows multiple users (1,...,K) t...

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Abstract

The present invention relates to a method and a device for detecting active spreading codes for a signal in a communication system and estimating power of the active spreading codes. Further, the present invention ensures efficient interference cancellation. Multiple correlations are performed at a single level of a spreading code tree, the produced output samples are then observed at this level during a defined period, and a decision for the activity and power is met for all existing codes via extracting and processing information from these samples. At the correlation step, unitary fast Walsh Hadamard transformation is performed at practically the highest spreading factor in the system.

Description

technical field [0001] The invention relates to the field of detection and power estimation of effective spreading codes for signals in communication systems. This efficient spreading code detection can be used for interference cancellation purposes in a communication system. More specifically, the present invention relates to a device for detecting an effective spreading code of a signal in a communication system and estimating the power of the effective spreading code, and the present invention relates to an effective spreading code for a signal in a communication system A method of detecting a frequency code and estimating the power of an effective spreading code, wherein the received signal comprises a sequence of data symbols spread in the received signal, and the spreading is performed by the spreading code and / or The spreading factor is defined. Background technique [0002] The world needs wireless communication technology now more than ever because more and more p...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04B1/707
CPCH04B1/70735H04J13/0044H04B2001/70935
Inventor 艾哈迈德·巴斯图格法布里齐奥·托马蒂斯
Owner TELEFON AB LM ERICSSON (PUBL)