Method and System for Multirate Multiuser Modulation

• US 20070091866A1
• Filed: 11/20/2006
• Published: 04/26/2007
• Est. Priority Date: 12/29/2000
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Nangia, Vijay, Ramasubramanian, Karthik, Baum, Kevin
• Granted Patent: US 7,701,839 B2
• Time in Patent Office: Days
• US Class Current: 370/344
• CPC Class Codes: H04B 2201/70703 using multiple or variable rates
• CPC Class Codes: H04J 13/004 Orthogonal
• CPC Class Codes: H04J 13/18 Allocation of orthogonal codes
• CPC Class Codes: H04L 5/023 Multiplexing of multicarrier modulation signals multicarrier modulation H04L27/2601

Abstract

A multi-rate interleaved frequency division multiple access (IFDMA) modulation scheme permits users to transmit at different data rates or to vary their data rates while providing frequency diversity and preserving low peak-to-average power ratios and orthogonality between user data rates. The modulation scheme allows user-specific data block and repetition sizes, as well as user-specific modulation codes. Code assignment rules are provided for maintaining orthogonality between the different user data rates. Block and phase ramp modulation codes can be used. Asynchronous transmissions by users are supported by ensuring that the length of the cyclic extension is sufficiently long to tolerate worst case relative signal arrival delays between users and the channel pulse response duration over the communication medium. The modulation scheme can be employed in wireless communication systems, such as cellular or paging systems.

Claims

1-55. -55. (canceled)

56. Method for performing orthogonal single carrier multiple access, the method comprising the steps of:

assigning a first user a first set of subcarriers comprising a first number of subcarriers, wherein spacing between neighboring subcarriers within the first set of subcarriers is uniform;

assigning a second user a second set of subcarriers comprising a second number of subcarriers, wherein spacing between neighboring subcarriers within the second set of subcarriers is uniform;

wherein the first number of subcarriers differs from the second number of subcarriers;

wherein the first and the second set of subcarriers are assigned in an orthogonal fashion; and

wherein the first and the second set of subcarriers are to be used for single carrier frequency division multiple access between the first and the second users.

57. The method of claim 56 wherein the first set of subcarriers are for used for transmitting a single carrier signal with nulls in frequency positions of the second set of subcarriers.

58. The method of claim 56 wherein the first set of subcarriers exist between the second set of subcarriers.

59. The method of claim 56 wherein the step of assigning the first and the second set of subcarriers comprises the step of specifying a first and a second symbol-block repetition value.

60. The method of claim 56 wherein the step of assigning the first and the second set of subcarriers comprises the step of specifying a first and a second symbol-block size.

61. The method of claim 56 wherein the step of assigning the first and the second set of subcarriers comprises the step of specifying a first and a second channelization code from a set of mutually orthogonal channelization codes.

62. The method of claim 56 wherein the step of assigning the first and the second set of subcarriers comprises the step of specifying a first and a second modulation code from a set of mutually orthogonal modulation codes.

63. The method of claim 56 wherein the step of assigning the first and the second set of subcarriers comprises the step of specifying a particular first and a second subcarrier and a a first and a second spacing between the assigned a first and a second set of subcarriers.

64. The method of claim 56 wherein the spacing between neighboring subcarriers within the second set of subcarriers comprises one subcarrier.

65. The method of claim 56 wherein the spacing between neighboring subcarriers within the second set of subcarriers comprises two or more subcarriers.

66. A method comprising the steps of:

receiving a subcarrier assignment;

generating a signal to be transmitted by a first user, wherein the signal comprises a first set of subcarriers corresponding to the received subcarrier assignment comprising a first number of subcarriers, wherein spacing between neighboring subcarriers within the first set of subcarriers is uniform;

wherein the first number of subcarriers differs from a second number of subcarriers assigned to a second user;

wherein the first and the second set of subcarriers are assigned in an orthogonal fashion;

wherein the first set of subcarriers are to be used for single carrier frequency division multiple access; and

transmitting the single carrier frequency division multiplexed signal.

67. The method of claim 66 wherein the signal comprises a user-specific symbol-block repetitions of a basic symbol-block when viewed in the time domain.

68. The method of claim 66 wherein the first set of subcarriers are used for transmitting a single carrier signal with nulls in frequency positions of the second set of subcarriers.

69. The method of claim 66 wherein the first set of subcarriers exist between the second set of subcarriers.

70. The method of claim 66 wherein the step of receiving a subcarrier assignment comprises the step of receiving a symbol-block repetition value.

71. The method of claim 66 wherein the step of receiving a subcarrier assignment comprises the step of receiving a symbol-block size.

72. The method of claim 66 wherein the step of receiving a subcarrier assignment comprises the step of receiving an orthogonal channelization code.

73. The method of claim 66 wherein the step of receiving a subcarrier assignment comprises the step of receiving one of a set of mutually orthogonal modulation codes.

74. The method of claim 66 wherein the step of receiving a subcarrier assignment comprises the step of receiving a subcarrier and a spacing between the assigned subcarriers.

76. The method of claim 66 wherein the spacing between neighboring subcarriers within the first set of subcarriers comprises one subcarrier.

77. The method of claim 66 wherein the spacing between neighboring subcarriers within the first set of subcarriers comprises two or more subcarriers.

78. A method comprising the steps of:

receiving a first subcarrier assignment at a first time instance;

generating a first single carrier signal to be transmitted, wherein the signal comprises a first set of subcarriers corresponding to the first received subcarrier assignment comprising a first number of subcarriers, wherein spacing between neighboring subcarriers within the first set of subcarriers is uniform;

transmitting the first single carrier signal;

receiving a second subcarrier assignment at a second time instance;

generating a second single carrier signal to be transmitted, wherein the signal comprises a second set of subcarriers corresponding to the second received subcarrier assignment comprising a second number of subcarriers, wherein spacing between neighboring subcarriers within the second set of subcarriers is uniform;

wherein the first number of subcarriers differs from the second number of subcarriers;

wherein the first and second set of subcarriers are used for single carrier frequency division multiple access; and

transmitting the second single carrier signal.