Multi-carrier OFDM UWB communications systems

• US 20050259758A1
• Filed: 05/24/2004
• Published: 11/24/2005
• Est. Priority Date: 10/01/2003
• Status: Active Grant

• Current Assignee: Callahan Cellular LLC (Intellectual Ventures LLC)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Razzell, Charles
• Granted Patent: US 7,809,067 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 5/026 using code division

Abstract

The present invention, generally speaking, provides for signaling methods in which multiple sub-bands of a transmission band are continuously occupied by an OFDM signal that would otherwise occupy only a single sub-band. In accordance with one embodiment, steps include producing an OFDM symbol; transforming the OFDM symbol to produce an OFDM signal; upsampling the OFDM signal to produce an upsampled OFDM signal; applying a pseudo-random code to the upsampled OFDM signal to produce a coded OFDM signal; and upconverting the coded OFDM signal to produce a radio frequency signal. In accordance with another embodiment, steps include producing an OFDM symbol; transforming the OFDM symbol to produce an OFDM signal; and upconverting the coded OFDM signal to produce a radio frequency signal; wherein the radio frequency signal occupies multiple ones of the following sub-bands: a first sub-band from about 3200 MHz to about 3700 MHz; a second sub-band from about 4000 MHz to about 4200 MHz; and a third sub-band from about 4200 MHz to about 4800 MHz. In accordance with still another embodiment, steps include producing a sequence of N consecutive identical OFDM symbols; transforming the OFDM symbols to produce corresponding OFDM signals; and upconverting the coded OFDM signal to produce a radio frequency signal; wherein the radio frequency signal occupies N sub-bands of a transmission band.

Claims

1. A signaling method comprising:

producing an OFDM symbol;

transforming the OFDM symbol to produce an OFDM signal; and

processing the OFDM signal to produce a radio frequency signal that occupies multiple sub-bands within a transmission band from about 3200 MHz to about 10300 MHz, each sub-band having a bandwidth of about 500 MHz.

2. The method of claim 1, wherein processing the OFDM signal comprises:

upsampling the OFDM signal to produce an upsampled OFDM signal;

applying a pseudo-random code to the upsampled OFDM signal to produce a coded OFDM signal; and

upconverting the coded OFDM signal to produce a radio frequency signal.

3. The method of claim 1, wherein the radio frequency signal occupies multiple ones of the following sub-bands:

a first sub-band from about 3200 MHz to about 3700 MHz;

a second sub-band from about 4000 MHz to about 4200 MHz; and

a third sub-band from about 4200 MHz to about 4800 MHz.

4. The method of claim 1, wherein processing the OFDM signal comprises:

upconverting the OFDM signal to produce a radio frequency signal;

wherein the radio frequency signal occupies multiple ones of the following sub-bands;

a first sub-band from about 3200 MHz to about 3700 MHz;

a second sub-band from about 4000 MHz to about 4200 MHz; and

a third sub-band from about 4200 MHz to about 4800 MHz.

5. The method of claim 1, comprising:

producing a sequence of N consecutive identical OFDM symbols; and

transforming the OFDM symbols to produce corresponding OFDM signals;

wherein processing the OFDM signal comprises upconverting the coded OFDM signal to produce a radio frequency signal that occupies N sub-bands of the transmission band.

6. A radio communication system comprising:

means for processing a communications signal that occupies multiple sub-bands within a transmission bandwidth of about 1500 MHz, each sub-band having a bandwidth of about 500 MHz; and

means for processing an OFDM symbol, including at least one of;

inverse transform means for transforming an OFDM symbol to produce an OFDM signal, said means for processing a signal processing the OFDM signal to produce a radio frequency signal; and

forward transform means for transforming an OFDM signal to produce an OFDM symbol, said means for processing a signal processing a baseband signal to produce the OFDM signal.

7. The apparatus of claim 6, wherein the radio frequency signal occupies multiple ones of the following sub-bands:

a first sub-band from about 3200 MHz to about 3700 MHz;

a second sub-band from about 4000 MHz to about 4200 MHz; and

a third sub-band from about 4200 MHz to about 4800 MHz.

8. The apparatus of claim 6, comprising:

forward transform means for transforming an OFDM signal to produce an OFDM symbol, said means for processing a signal processing a baseband signal to produce the OFDM signal; and

means for selecting a subset of the multiple sub-band and for receiving the radio frequency signal within the subset of sub-bands to produce the baseband signal.

9. The apparatus of claim 6, comprising:

forward transform means for transforming an OFDM signal to produce an OFDM symbol, said means for processing a signal processing a baseband signal to produce the OFDM signal; and

means for receiving the radio frequency signal within multiple sub-bands and non-coherently combining signals from the multiple sub-bands to produce the baseband signal.

10. The apparatus of claim 6, comprising:

forward transform means for transforming an OFDM signal to produce an OFDM symbol, said means for processing a signal processing a baseband signal to produce the OFDM signal; and

means for sampling the radio frequency signal within multiple sub-bands to produce the baseband signal, at a comparatively high sampling rate compared to a sampling rate for sampling the radio frequency signal within a single sub-band;

wherein the OFDM signal transformed by the forward transform means is a column vector of complex values, the column vector being of a comparatively large size compared to a size for representing a single sub-band.

11. The apparatus of claim 10, comprising:

means for decomposing the column vector into multiple smaller column vectors and for applying the multiple smaller column vectors sequentially in time to the forward transform means.

12. The apparatus of claim 11, wherein the number of smaller column vectors is equal to the number of multiple sub-bands.

13. The apparatus of claim 6, comprising:

means for repeating OFDM symbols such that, at least during one mode of operation, each OFDM symbol occurs as part of a sequence of N identical OFDM symbols.

14. The apparatus of claim 13, wherein N is equal to the number of multiple sub-bands.