Communication apparatus and a method of transmitting data therefor

• US 7,751,307 B2
• Filed: 11/18/2005
• Issued: 07/06/2010
• Est. Priority Date: 01/11/2005
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Muck, Makus, De Courville, Marc Bernard, Rouquette-Leveil, Stephanie
• Primary Examiner(s): Juntima; Nittaya
• Application Number:
  US11/721,574
• Publication Number:
  US 20080101487A1
• Time in Patent Office: 1,691 Days
• Field of Search: 370/252, 370/203, 370/206, 370/208, 370/343, 370/344, 370/465, 375/260, 375/295
• US Class Current: 370/208
• CPC Class Codes: H04L 27/261 Details of reference signals
• CPC Class Codes: H04L 27/262 Reduction thereof by selection of pilot symbols

Abstract

An Orthogonal Frequency Division Multiplex (OFDM) transmitter (100) comprises a symbol generator (103) for generating a first OFDM symbol comprising user data and pilot data where the pilot data comprises a set of predetermined non-orthogonal pilot symbols. A weight generator (109) uses an amplitude estimator (107) for selecting a set of weights for the pilot data of the first OFDM symbol in response to a time domain amplitude variation characteristic of the first OFDM symbol. In particular, the peak to average power ratio may be determined. The set of weights are selected from a discrete alphabet of weights. A weight processor (113) determines a second OFDM symbol by weighting the pilot symbols by the set of weights. The second OFDM symbol is transmitted to a receiver without transmitting identification of the selected set of weights. The receiver may perform a blind detection of the applied weights and may compensate the received pilot symbols for the estimated weight.

Claims

1. A communication apparatus for a communication system, the communication apparatus including an Orthogonal Frequency Division Multiplex, OFDM, transmitter for transmitting OFDM symbols comprising:

means for generating a first OFDM symbol comprising user data and pilot data;

the pilot data comprising a set of predetermined non-orthogonal pilot symbols;

means for selecting a set of weights for the pilot data of the first OFDM symbol in response to a time domain amplitude variation characteristic of the first OFDM symbol, the set of weights being selected from a discrete alphabet of weights;

means for generating a second OFDM symbol by weighting the pilot symbols by the set of weights; and

means for transmitting the second OFDM symbol to a receiver without transmitting identification of the selected set of weights;

wherein the means for transmitting is arranged to transmit the second OFDM symbol on a first antenna and the transmitter further comprises;

means for generating a third OFDM symbol by phase rotation of the second OFDM symbol; and

means for transmitting the third OFDM symbol to the receiver on a second antenna without transmitting identification of the selected set of weights.

2. A communication apparatus as claimed in claim 1 wherein the OFDM transmitter comprises means for Space Time Coding OFDM symbols transmitted on the first and second antennas.

3. A communication apparatus as claimed in claim 1 wherein the OFDM transmitter comprises means for Spatial Division Multiplexing of the OFDM symbols transmitted on the first and second antennas.