US 7,352,829 B2 · Data-aided channel estimation

Abstract

Forming a channel estimate for a communications channel in a communication system, which a receiver that receives over the communications channel signals including pilot symbols, control symbols, and a set of data symbols. A pilot-only based channel estimate is calculated using the pilot symbols in a first pass through a portion of the control channel. Then pseudo pilot symbols are generated on a basis of a control channel, and then are used to refine the pilot-only based channel estimate. A set of data symbols is then weighted using the refined channel estimate, and the weighted set of symbols is output to a decoder stage.

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Claims20

Dependent claims

A method for forming a channel estimate for a communications channel in a communication system, the communication system having a receiver that receives over the communications channel signals including pilot symbols, control symbols, and a set of data symbols, the method comprising:

a) calculating a pilot-only based channel estimate using the pilot symbols in a first pass through a portion of a control channel;
b) generating pseudo pilot symbols on a basis of a control channel using the pilot-only based channel estimate;
c) using the pseudo pilot symbols to refine the pilot-only based channel estimate;
d) weighting the set of data symbols using the refined channel estimate;
and
e) outputting the weighted set of symbols to a decoder stage.

3 more elements

Dependencies are inferred from the claim text.

Description4,558 words

Summary1,348 words

#The present invention relates to third generation CDMA mobile systems, and more particularly to data-aided channel estimation of third-generation CDMA signals.

#Third generation code division multiple access (CDMA) mobile systems, such as Universal Mobile Telecommunication System 3GPP (3rd Generation Partnership Program) Wideband CDMA include on the uplink channel pilot symbols which are used by the receiver for channel estimation and other demodulation functions.

#FIG. 7 illustrates a block diagram of a conventional channel estimation receiver 700 that uses only pilot symbols to produce a channel estimate. For the lth finger, pilot symbols of the nth slot are extracted from the received descrambled and despread data channel (DPCCH) signal, and the functional section 701 computes a new slot average. This new slot average is filtered in the functional section 701 by a weighted mean square error (WMSA) non-causal channel estimation filter to produce a pilot-only based channel estimate ĉi,l. The estimates from the WMSA filter are further linearly interpolated at the control channel (DPCCH) symbol rate. The channel estimate is then input to complex conjugator 702 which calculates and outputs a complex conjugate of the pilot-only based channel estimate ĉ*i,l. Simultaneously, data on the data channel is delayed in delay 704 by D1 slots (to account for the non-causal WMSA filter delay) and channel-corrected, that is, multiplied in multiplier 703 by the complex conjugate of the pilot-only based channel estimate ĉ*i,l. While this pilot-only based channel estimation receiver 700 is simple, it has disadvantages in that there is poor channel estimate quality in adverse channels, thereby forcing the transmitter to increase either transmit power or coding gain at the expense of the information data rate.

Brief description of the drawings8 figures

#The foregoing and other features of the present invention will be more readily apparent from the following detailed description and drawings of illustrative embodiments of the invention, in which:

#FIG. 1 illustrates an overview of the data-aided channel estimation receiver according to a schematic embodiment of the present invention;

#FIGS. 2A and 2B illustrate a frame structure for uplink data and control channels;

Detailed description2,992 words

#By way of overview, the present invention provides a method resulting in an improved channel estimate that enhances system error-rate performance and system capacity, as measured by a reduction in information-bit-energy to noise-spectral-density ratio (Eb/N0) required to meet a specified block error rate (BLER). The method forms the channel estimate by operating on raw demodulator output, thereby not requiring a large amount of memory. The channel estimation method also results in low latency.

#The present invention is described by first providing an overview of the data-aided channel estimation receiver of the present invention, then an overview of the uplink of wideband CDMA, a list of the notation used throughout the specification, followed by conventional channel estimation, which then provides a basis for channel estimation according to the present invention. The details of three embodiments of the channel estimation according to the present invention are described first by referring to the block diagram of FIG. 3, and then with reference to the flowcharts of FIGS. 4-6, respectively.

#A. Data-Aided Channel Estimation Receiver Overview

Facts

Application

10/755,971Filed 12 Jan 2004

Published

US 2005/0152478 A114 Jul 2005

Granted

1 Apr 2008

Term ended

31 Mar 2026

Estimated · how

20 years from earliest known nonprovisional domestic filing plus recorded patent term adjustment, including 809 days of adjustment. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification3 codes

H04L 25/0236
With extension to other symbols: using estimation of the other symbols
H04L 25/0232
With extension to other symbols: by interpolation between sounding signals
H04L
Digital communication

Timeline

12 Jan 2004Application filedUS 10/755,971
12 Jan 2004Assigned to Infineon Technologies Morphics, Inc.assignment of assignor's interest
6 Jul 2004Assigned to Infineon Technologies North America Corp.merger
13 Jul 2004Assigned to Infineon Technologies AGassignment of assignor's interest
29 Sep 2004Assigned to Infineon Technologies AGassignment of assignor's interest
14 Jul 2005PublishedUS 2005/0152478 A1
1 Apr 2008GrantedUS 7,352,829 B2
31 Mar 2026Term endedEstimated, includes 809 days of adjustment

Data-aided channel estimation

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Data-aided channel estimation

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims20

Description4,558 words

Drawings

Classification3 codes

Life of this patent

Description4,558 words