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Reduced complexity channel estimation for wireless communication systems

A technology of wireless communication system and channel estimation, applied in the direction of channel estimation, transmission system, baseband system, etc.

Inactive Publication Date: 2005-12-28
QUALCOMM INC
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  • 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

Examples

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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<N. These M available subbands are also called data subbands. The remaining N-M subbands are not used for data transmission and are used as guard subbands to allow the OFDM system to meet the spectral mask requirements. The M available subbands include subbands F to F+M-1.

[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 are provided that are able to use a substantially smaller number of complex multiplication operations to obtain the same channel estimate than the brute force approach to obtaining the channel estimate. In one approach, an intermediate vector B is first derived (418) based on K subvectors of vector H for channel frequency response estimation and at least two DFT submatrices of DFT matrix W, where K>1. An intermediate matrix A of the DFT matrix is ​​also obtained (420). A least squares channel impulse response estimate is then derived based on intermediate vector B and intermediate matrix A (422). In one implementation, the intermediate vector B is first computed based on the DFT of the matrix HTxL formed by the vector H to provide the matrix GLxL. The inner product between the columns of the basic DFT submatrix W1 and the rows of the matrix GL×L is then computed to obtain the terms 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 Applications(China)
IPC IPC(8): H04L25/02H04L27/22H04L27/26
CPCH04L25/0242H04L27/2601H04L25/0204H04B7/2612H04B7/2621H04L27/223
Inventor 阿南德·苏布拉马尼亚姆塔梅尔·卡多斯
Owner QUALCOMM INC
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