Orthogonal Frequency Division Multiple Access with carrier sense

• US 9,363,795 B2
• Filed: 02/09/2013
• Issued: 06/07/2016
• Est. Priority Date: 01/25/2008
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Hassan, Amer A., Sapek, Adam, Shen, Hui, Kuehnel, Thomas W., Wu, Deyun, Huitema, Christian
• Primary Examiner(s): DUONG, CHRISTINE T
• Application Number:
  US13/763,671
• Publication Number:
  US 20130155980A1
• Time in Patent Office: 1,214 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H04L 27/0006 Assessment of spectral gaps suitable for allocating digitally modulated signals, e.g. for carrier allocation in cognitive radio for spectrum sharing between different networks H04W16/14
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0037 Inter-user or inter-terminal allocation
• CPC Class Codes: H04L 5/0064 Rate requirement of the data, e.g. scalable bandwidth, data priority
• CPC Class Codes: H04L 5/0094 Indication of how sub-channels of the path are allocated
• CPC Class Codes: H04W 72/04 Wireless resource allocation
• CPC Class Codes: H04W 74/0808 using carrier sensing, e.g. carrier sense multiple access [CSMA]

Abstract

A communication system in which an access point and one or more devices communicating through the access point adaptively apply Orthogonal Frequency Division Multiple Access (OFDMA). The access point may assign orthogonal subcarriers to devices as in conventional OFDMA, but the access point senses activity on the subcarriers and selects subcarriers without activity for assignment. In an alternative approach, a device that is configured for OFDMA communication may receive a channel assignment from a device that does not support OFDMA. The OFDMA-capable device may use only a portion of the subcarriers in the assigned channel, which may be communicated to the non-OFDMA device. During the non-OFDMA device may then ignore unused subcarriers in error detection and correction to avoid incorrectly classifying communications as erroneous. Information about OFDMA capabilities, subcarrier assignments and subcarriers in use may be communicated as information elements in network control communications, such as beacons and probe messages.

Claims

1. A method performed on a computing device, the method comprising:

selecting, by the computing device, a set of individual subcarriers, where each of the individual subcarriers in the selected set is not in active use according to signal activity levels detected on the each of the individual subcarriers;

assigning, by the computing device, the selected set of individual subcarriers to another device;

receiving, by the computing device from the another device, a message communicated wirelessly via a subset of the assigned set of individual subcarriers;

receiving, by the computing device from the another device, a list that identifies any of the individual subcarriers of the assigned set that are not part of the subset used to send the message; and

modifying, by the computing device based on the received list, error detection and correction processing of the received message such that a lack of information in the any of the individual subcarriers identified in the list is not interpreted as an error.

2. The method of claim 1 where the computing device comprises a wireless access point.

3. The method of claim 1 where the assigning includes sending an assignment of the set as part of a beacon transmission.

4. The method of claim 1 further comprising repeating the selecting, the assigning, the receiving the list, and the modifying in response to further detected signal activity levels.

5. A computing device comprising:

a wireless radio;

an error correction component;

at least one processor;

memory; and

computer-executable instructions that, based on execution by the at least one processor, configure the computing device to;

select a set of individual subcarriers, where each of the individual subcarriers in the selected set is not in active use according to signal activity levels detected on the each of the individual subcarriers;

assign the selected set of individual subcarriers to another device;

receive, via the wireless radio from the another device, a message communicated wirelessly via a subset of the assigned set of individual subcarriers;

receive, via the wireless radio from the another device, a list that identifies any of the individual subcarriers of the assigned set that are not part of the subset used to send the message; and

modify, based on the received list, error detection and correction processing by the error correction component of the received message such that a lack of information in the any of the individual subcarriers identified in the list is not interpreted as an error.

6. The computing device of claim 5 where the computing device comprises a wireless access point.

7. The computing device of claim 5 where the set of individual subcarriers is assigned to the another device via a beacon transmission.

8. The computing device of claim 5 where the error detection and correction processing is modified in response to signal activity levels.

9. The computing device of claim 5 where the subset of the assigned set further comprises at least one subcarrier from a different set than the assigned set.

10. At least one computer-readable medium comprising:

memory that comprises computer-executable instructions that, based on execution by at least one processor of a computing device, configure the computing device to perform actions comprising;

selecting a set of individual subcarriers, where each of the individual subcarriers in the selected set is not in active use according to signal activity levels detected on the each of the individual subcarriers;

assigning, to another device, the selected set of individual subcarriers;

receiving, from the another device, a message communicated wirelessly via a subset of the assigned set of individual subcarriers;

receiving, from the another device, a list that identifies any of the individual subcarriers of the assigned set that are not part of the subset used to send the message; and

modifying, based on the received list, error detection and correction processing of the received message such that a lack of information in the any of the individual subcarriers identified in the list is not interpreted as an error.

11. The at least one computer-readable medium of claim 10 where the computing device comprises a wireless client device.

12. The at least one computer-readable medium of claim 10 where the set of individual subcarriers is assigned to the another device via a beacon transmission.

13. The at least one computer-readable medium of claim 10, the actions further comprising repeating the selecting, the assigning, the receiving the list, and the modifying in response to further detected signal activity levels.