Reduced complexity channel estimation for wireless communication systems

A wireless communication system, channel estimation technology, applied in channel estimation, transmission system, baseband system, etc.

Inactive Publication Date: 2010-05-26
QUALCOMM INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

As described in detail below, depending on the number of assigned subbands used for pilot transmission and the impulse response of the channel, signal processing can be computationally intensive and require a large number of complex multiplication operations

Method used

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  • Reduced complexity channel estimation for wireless communication systems
  • Reduced complexity channel estimation for wireless communication systems
  • Reduced complexity channel estimation for wireless communication systems

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Embodiment Construction

[0024] The channel estimation techniques described here can be used in any communication system with multiple subbands. For simplicity, these techniques are described specifically for OFDM systems.

[0025] figure 1 A subband structure 100 that may be used in an OFDM system is shown. The overall system bandwidth of the OFDM system is W MHz, and OFDM is used to divide this bandwidth into N orthogonal subbands. The bandwidth of each subband is W / N MHz. In a typical OFDM system, only M of the total N subbands are used for data transmission, where M

[0026] For OFDM, the data to be transmitted on each subband is first modulated (ie, symbol mapped) using the particular modulation method selected for that su...

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Abstract

Techniques to derive a channel estimate using substantially fewer number of complex multiplications than with a brute-force method to derive the same channel estimate. In one method, an intermediate vector B is initially derived based on K sub-vectors of a vector H for a channel frequency response estimate and at least two DFT sub-matrices for a DFT matrix W , where K > 1. An intermediate matrix for A the DFT matrix W is also obtained. A least square channel impulse response estimate is then derived based on the intermediate vector B and the intermediate matrix A . In one implementation, the intermediate vector B is obtained by first computing DFTs of a matrix HTXL , which is formed based on the vector H, to provide a matrix GLXL. Inner products between the columns of a base DFT sub-matrixW1 and the rows of the matrix GLXL are then computed to obtain the entries of the intermediate vector B .

Description

[0001] Cross References to Related Applications [0002] This application claims the benefit of US Provisional Patent Application No. 60 / 427,896, filed November 19, 2002, which is hereby incorporated by reference in its entirety. technical field [0003] The present invention relates generally to data communications, and more particularly to techniques for performing channel estimation with reduced complexity. Background technique [0004] Wireless communication systems are widely used to provide various types of communication, such as voice, packet data, and so on. These systems may be multiple access systems capable of supporting communication with multiple users by pooling available system resources. Examples of such multiple-access systems include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, and Orthogonal Frequency Division Multiple Access (OFDMA) systems. [0005] Orthogonal Frequency Division Multiplexing (OFDM) effecti...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L27/22H04L25/02H04L27/26
CPCH04L25/0242H04L25/0208H04L27/2601H04L25/0204H04B7/2612H04B7/2621H04L27/223
Inventor 阿南德·苏布拉马尼亚姆塔梅尔·卡多斯
Owner QUALCOMM INC
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