Cognitive Ultrawideband-Orthogonal Frequency Division Multiplexing

• US 20070133387A1
• Filed: 12/08/2006
• Published: 06/14/2007
• Est. Priority Date: 12/08/2005
• Status: Active Grant

• Current Assignee: University of South Florida (State University System of Florida)
• Original Assignee: University of South Florida (State University System of Florida)
• Inventors: Arslan, Huseyin, Sahin, Mustafa
• Granted Patent: US 7,652,979 B2
• Time in Patent Office: Days
• US Class Current: 370/206
• CPC Class Codes: H04B 1/719 Interference-related aspects
• CPC Class Codes: H04L 27/0004 using wavelets

Abstract

The present invention provides a system and method for transmitting an ultrawideband (UWB) signal that is composed of an orthogonal frequency-division multiplexing (OFDM) based signal that is transmitted in an underlay manner and an impulse radio based signal that is transmitted in an overlay manner. The system and method are effective in determining an interference temperature for each of multiple carriers within the UWB signal and classifying each one of the multiple carriers of the channel as being an interfered carrier or a non-interfered carrier based on the interference temperature for each one of multiple carriers. The desired signal is then transmitted on the interfered carriers at a signal power that is not greater than the power limit of the underlay UWB policy and on the non-interfered carriers at a signal power that is greater than the power limit of the underlay UWB policy.

Claims

1. A method of transmitting an ultrawideband (UWB) signal that is composed of an orthogonal frequency-division multiplexing (OFDM) based signal that is transmitted in an underlay manner and an impulse radio based signal that is transmitted in an overlay manner, wherein the UWB signal further comprises an underlay UWB policy, the method comprising the steps of:

determining an interference temperature for each of a plurality of carriers within the UWB signal;

classifying each one of the plurality of carriers of the channel as being an interfered carrier or a non-interfered carrier based on the interference temperature for each one of the plurality of carriers;

transmitting the signal on the interfered carriers at a signal power that is not greater than the power limit of the underlay UWB policy; and

transmitting the signal on the non-interfered carriers at a signal power that is greater than the power limit of the underlay UWB policy.

2. The method of claim 1, wherein the non-interfered carriers further comprise side-lobes, the method further comprising the step of employing transmission techniques for the non-interfered carrier which are effective in limiting the side-lobes of the carriers, thereby reducing interference within the plurality of carriers.

3. The method of claim 1, further comprising the step of classifying each one of the plurality of carriers as being either an underlay carrier or an overlay carrier, wherein an underlay carrier employs a low-powered sinc function for transmission of the signal and an overlay carrier employs a prolate spheroidal wavelet function for transmission of the signal.

4. The method of claim 3, wherein inter-carrier interference is created by the interaction between the overlay and the underlay carriers, the method further comprising the step of employing successive interference cancellation to reduce the inter-carrier interference.

5. The method of claim 1, wherein the step of determining an interference temperature for each of a plurality of carriers further comprises performing an adaptive windowing technique to estimate the noise power taking into account the variation of the noise statistics across the plurality of OFDM carriers and the OFDM transmission symbols.

7. The system of claim 1, wherein the non-interfered carriers further comprise side-lobes and the transmitter further comprises means for employing transmission techniques for the non-interfered carrier which are effective in limiting the side-lobes of the carriers, thereby reducing interference within the plurality of carriers.

8. The system of claim 1, wherein the classification algorithm further comprises means for classifying each one of the plurality of carriers as being either an underlay carrier or an overlay carrier, wherein an underlay carrier employs a low-powered sinc function for transmission of the signal and an overlay carrier employs a prolate spheroidal wavelet function for transmission of the signal.

9. The system of claim 8, wherein inter-carrier interference is created by the interaction between the overlay and the underlay carriers, the transmitter further comprising means for employing successive interference cancellation to reduce the inter-carrier interference.

10. The system of claim 1, wherein the interference temperature identification algorithm further determines the interference temperature for each of the plurality of carriers by performing an adaptive windowing technique to estimate the noise power taking into account the variation of the noise statistics across multiple OFDM carriers and the OFDM transmission symbols.

6. A system for transmitting an ultrawideband (UWB) signal that is composed of an orthogonal frequency-division multiplexing (OFDM) based signal that is transmitted in an underlay manner and an impulse radio based signal that is transmitted in an overlay manner, wherein the UWB channel comprises an underlay policy, the system comprising:

an interference temperature identification algorithm for determining an interference temperature for each of a plurality of carriers within the UWB signal;

a classification algorithm for classifying each one of the plurality of carriers of the channel as being an interfered carrier or a non-interfered carrier based on the interference temperature for each one of the plurality of carriers; and

a transmitter for transmitting the signal on the interfered carriers at a signal power that is not greater than the power limit of the underlay UWB policy and for transmitting the signal on the non-interfered carriers at a signal power that is greater than the power limit of the UWB channel underlay policy.