Method, apparatus, and system for power amplifier efficiency improvement

• US 7,411,896 B1
• Filed: 08/28/2002
• Issued: 08/12/2008
• Est. Priority Date: 08/29/2001
• Status: Active Grant

• Current Assignee: Ostendo Technologies Inc.
• Original Assignee: Ostendo Technologies Inc.
• Inventors: Karsi, Murat F.
• Primary Examiner(s): Chan; Wing F.
• Assistant Examiner(s): Duong; Duc T
• Application Number:
  US10/230,018
• Time in Patent Office: 2,176 Days
• Field of Search: 370/203, 370/206, 370/208, 375/259, 375/260, 375/297, 375/320, 375/346
• US Class Current: 370/208
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 2201/70706 with means for reducing the peak-to-average power ratio
• CPC Class Codes: H04L 27/2614 Peak power aspects

Abstract

According to one embodiment of the present invention, a method is provided in which a set of data symbols is partitioned into a plurality of subsets. The data symbols are used to modulate the sub-carriers that transmit data signals from a transmitter to a receiver. The subsets of the data symbols are assigned to the corresponding sub-carriers based on a predefined set of assignments. The assignment which results in the minimum PAPR is then chosen. The information identifying which assignment is used is communicated to the receiver which then uses this information to place the data symbols back to their true positions.

Claims

1. A method comprising:

partitioning a set of data symbols having true positions into a plurality of subsets of data symbols, the data symbols being used to modulate a set of sub-carriers, the sub-carriers being used to transmit signals from a transmitter to a receiver;

assigning the subsets of data symbols to the corresponding sub-carriers based on a predefined set of assignments, the assignments being chosen such that a peak to average power ratio (PAPR) of the transmitted signals is minimal; and

communicating in a separate channel, information identifying the chosen assignments to the receiver which is used by the receiver to place the data symbols back to the true positions;

wherein, if the assignment of data symbols to the sub-carriers are made by reordering a segment of the data symbol stream that is longer than the number of symbols that can be held by a single OFDM symbol, the assignment information for the respective segment is sent to the receiver embedded in one of the OFDM symbols.

2. A method comprising:

partitioning a set of data symbols having true positions into a plurality of subsets of data symbols, the data symbols being used to modulate a set of sub-carriers, the sub-carriers being used to transmit signals from a transmitter to a receiver;

assigning the subsets of data symbols to the corresponding sub-carriers based on a predefined set of assignments, the assignments being chosen such that a peak to average power ratio (PAPR) of the transmitted signals is minimal; and

communicating in a separate channel, information identifying the chosen assignments to the receiver which is used by the receiver to place the data symbols back to the true positions;

wherein, if the assignment of data symbols to the sub-carriers are made by reordering a segment of the data symbol stream that is longer than the number of symbols that can be held by a single OFDM symbol, the assignment information for multiple such segments are sent together to the receiver in one or more OFDM symbols dedicated to communicating the assignment information.

3. A method comprising:

partitioning a set of data symbols having true positions into a plurality of subsets of data symbols, the data symbols being used to modulate a set of sub-carriers, the sub-carriers being used to transmit signals from a transmitter to a receiver;

assigning the subsets of data symbols to the corresponding sub-carriers based on a predefined set of assignments, the assignments being chosen such that a peak to average power ratio (PAPR) of the transmitted signals is minimal; and

communicating information identifying the chosen assignments to the receiver which is used by the receiver to place the data symbols back to the true positions;

wherein assigning includes;

for all candidate assignments, assigning the data symbols to the corresponding sub-carriers over a data segment;

performing an Inverse Discrete Fourier Transform (IDFT) function on the respective data segment; and

measuring the peak level of the IDFT output; and

choosing the assignment with the smallest peak.

4. The method of claim 3 wherein IFFT is used instead of IDFT.

5. The method of claim 3 wherein calculations of signal peak value corresponding to the candidate assignments are performed in parallel.

6. The method of claim 3 wherein calculations of signal peak value corresponding to the candidate assignments are performed sequentially.