METHOD AND APPARATUS FOR COMMUNICATION BY A SECONDARY USER OF SPECTRUM

• US 20080130715A1
• Filed: 12/05/2006
• Published: 06/05/2008
• Est. Priority Date: 12/05/2006
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Gorday, Paul E., Taubenheim, David B., Callaway, Edgar H.
• Granted Patent: US 7,706,465 B2
• Time in Patent Office: Days
• US Class Current: 375/146
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• 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 5/0058 Allocation criteria

Abstract

During operation of a node in a secondary communication system (100) data enters a spreader (301) and is appropriately spread. The spread data is then modulated onto all available channels using a multi-carrier OFDM modulation technique. This entails the spread data being modulated onto those channels that are currently being used by the primary communication system (120). Finally, a transmitter (303) transmits the spread data only over carriers that will not interfere with the primary communication system.

Claims

1. A method for transmitting data, the method comprising the steps of:

receiving data to be transmitted;

spreading the data;

modulating the data onto a plurality of available channels;

transmitting the spread data over a number of channels that is less than the plurality of available channels.

2. The method of claim 1 wherein the step of transmitting the spread data comprises the steps of:

determining channels that will not interfere with a primary communication system; and

transmitting the spread data over the channels that will not interfere with the primary communication system.

3. The method of claim 2 wherein the step of transmitting the spread data comprises the step of transmitting the spread data utilizing an OFDM transmission technique.

4. The method of claim 1 wherein the step of transmitting the spread data comprises the step of transmitting the spread data utilizing an OFDM transmission technique.

5. The method of claim 1 wherein the step of receiving the data comprises the step of receiving data for initiating communications between two nodes in a secondary communication system.

6. The method of claim 1 wherein the step of spreading the data comprises the step of modulo 2 adding an orthogonal code to each data symbol.

7. The method of claim 6 wherein the orthogonal code comprises a Walsh code.

8. A method comprising the steps of:

receiving data for initiating communications between two nodes in a secondary communication system;

spreading the data over a first number of channels;

determining a second number of channels that will not interfere with a primary communication system, wherein the second number of channels is less than the first number of channels;

transmitting the spread data over the second number of channels.

9. The method of claim 8 wherein the step of transmitting the spread data comprises the step of transmitting the spread data utilizing an OFDM transmission technique.

10. The method of claim 8 wherein the step of spreading the data comprises the step of modulo 2 adding an orthogonal code to each data symbol.

11. The method of claim 10 wherein the orthogonal code comprises a Walsh code.

12. An apparatus comprising:

a spreader receiving data and spreading the data over a plurality of available channels; and

a transmitter transmitting the spread data over a number of channels that is less than the plurality of available channels.

13. The apparatus of claim 12 further comprising:

a signal sensor determining channels that will not interfere with a primary communication system; and

wherein the transmitter transmits the spread data over the channels that will not interfere with the primary communication system.

14. The apparatus of claim 12 wherein the transmitter comprises an OFDM transmitter.

15. The apparatus of claim 12 wherein the data comprises data for initiating communications between two nodes in a secondary communication system.

16. The apparatus of claim 12 wherein the spreader spreads the data by modulo 2 adding an orthogonal code to each data symbol.

17. The apparatus of claim 16 wherein the orthogonal code comprises a Walsh code.