Methods and apparatuses using filter banks for multi-carrier spread spectrum signals

Patent metadata

Field	Value
Publication number	US-9369866-B2
Application number	US-201414498035-A
Country	US
Kind code	B2
Filing date	Sep 26, 2014
Priority date	Dec 5, 2011
Publication date	Jun 14, 2016
Grant date	Jun 14, 2016

Abstract

A transmitter includes a synthesis filter bank to spread a data symbol to a plurality of frequencies by encoding the data symbol on each frequency, apply a common pulse-shaping filter, and apply gains to the frequencies such that a power level of each frequency is less than a noise level of other communication signals within the spectrum. Each frequency is modulated onto a different evenly spaced subcarrier. A demodulator in a receiver converts a radio frequency input to a spread-spectrum signal in a baseband. A matched filter filters the spread-spectrum signal with a common filter having characteristics matched to the synthesis filter bank in the transmitter by filtering each frequency to generate a sequence of narrow pulses. A carrier recovery unit generates control signals responsive to the sequence of narrow pulses suitable for generating a phase-locked loop between the demodulator, the matched filter, and the carrier recovery unit.

First claim

What is claimed is:

1. A method, comprising:
generating, with a common pulse shaping and spectrum distribution filter and modulator of a spread spectrum transmitter, a Filter-Bank Multi-Carrier Spread-Spectrum (FB-MC-SS) signal as an underlay control channel having a power level below an apparent noise level for other signals of a frequency spectrum responsive to receiving an input signal, the FB-MC-SS signal including at least one data symbol from the input signal redundantly modulated onto each subcarrier of the FB-MC-SS signal such that each subcarrier includes the same at least one data symbol, wherein the at least one data symbol passes through the common pulse shaping filter prior to being modulated and up-converted for transmission.

2. The method of claim 1 , wherein generating the FB-MC-SS signal includes:
applying the common pulse shaping and spectrum distribution filter to the input signal to generate a baseband output signal; and
modulating the baseband output signal with the modulator for RF transmission of the FB-MC-SS signal.

3. The method of claim 1 , further comprising transmitting a communication signal as an overlay signal having a power level above the apparent noise level and over a subgroup of the FB-MC-SS signal.

4. The method of claim 3 , wherein transmitting the communication signal employs adaptive radio to select transmission thereof to be within a frequency band determined to be in a clear band from interference by other communication signals that exist within the frequency spectrum.

5. The method of claim 4 , further comprising determining the clear band by using the FB-MC-SS signal to detect interference with the other communication signals.

6. The method of claim 3 , wherein transmitting the communication signal includes transmitting a Filter-Bank Multi-Carrier (FB-MC) signal as the overlay signal.

7. The method of claim 1 , wherein generating the FB-MC-SS signal includes spreading the input signal over a set of spectrally isolated subcarrier bands.

8. The method of claim 1 , wherein generating the FB-MC-SS signal includes generating the FB-MC-SS signal as a orthogonal frequency-division multiplexing (OFDM) based spread spectrum signal.

9. The method of claim 1 , wherein generating the FB-MC-SS signal includes generating the FB-MC-SS signal as a filtered multi-tone (FMT) based spread spectrum signal.

10. A spread-spectrum transmitter, comprising:
a common pulse shaping and distribution module and modulator that in combination are configured to generate a Filter-Bank Multi-Carrier Spread-Spectrum (FB-MC-SS) signal as an underlay control channel having a power level below an apparent noise level of a frequency spectrum, the FB-MC-SS signal including at least one data symbol modulated onto each subcarrier of the FB-MC-SS signal such that each subcarrier includes the same at least one data symbol, wherein the at least one data symbol passes through the common pulse shaping filter prior to being modulated and up-converted for RF transmission.

11. The spread-spectrum transmitter of claim 10 , wherein the common pulse shaping and distribution module are configured to receive an input signal including the at least one data symbol and generate a baseband output signal.

12. The spread-spectrum transmitter of claim 11 , wherein the modulator is configured to receive the baseband output signal and generate the FB-MC-SS signal for RF transmission.

13. The spread-spectrum transmitter of claim 12 , wherein the common pulse shaping and distribution module includes a synthesis filter bank configured to band-limit a stream of data symbols at each band of the synthesis filter bank, and to apply spreading gain factors to each band of the synthesis filter bank.

14. The spread-spectrum transmitter of claim 13 , wherein the synthesis filter bank includes a square-root Nyquist filter applied to each band of the synthesis filter bank.

15. The spread-spectrum transmitter of claim 12 , wherein the modulator is configured to modulate the baseband output signal according to a modulation scheme selected from the group consisting of binary phase shift keying (BPSK) quadrature phase shift keying (QPSK), and quadrature amplitude modulation (QAM).

16. The spread-spectrum transmitter of claim 11 , wherein the common pulse shaping and distribution module are configured to spread the input signal over a set of spectrally isolated subcarrier bands to generate the FB-MC-SS signal.

17. The spread-spectrum transmitter of claim 10 , wherein the transmitter is further configured to:
detect white spaces over the frequency spectrum using the FB-MC-SS signal over which primary users of the frequency spectrum are not currently transmitting data; and
transmit FB-MC signals over subcarriers of the frequency spectrum that occupy at least some of the white space.

18. The spread-spectrum transmitter of claim 17 , wherein the FB-MC signals have higher power and more complex data sets in comparison to the FB-MC-SS signal.

19. The method of claim 18 , wherein the FB-MC signals are transmitted for a temporary duration during which the white spaces are detected.

Assignees

• Battelle Energy Alliance Llc

Inventors

• Moradi Hussein
• Farhang Behrouz
• Kutsche Carl A

Classifications

• H04J11/0023 Primary

  Interference mitigation or co-ordination (direct sequence spread spectrum [DSSS] systems H04B1/7097; frequency hopping H04B1/713; allocation criteria for ingress interference avoidance H04L5/0062; frequency allocation criteria for requirements on out-of-channel emissions H04L5/0066; arrangements for removing intersymbol interference or baseband equalisers H04L25/03006; peak power aspects in multicarrier modulation H04L27/2614; power management H04W52/00; traffic scheduling H04W72/54, H04W72/541) · CPC title

• H04K3/25

  based on characteristics of target signal or of transmission (as countermeasure against surveillance H04K3/827), e.g. using direct sequence spread spectrum or fast frequency hopping (spread spectrum techniques H04B1/69) · CPC title

• H04L9/0875

  based on channel impulse response [CIR] · CPC title

• H04L5/0021

  in which codes are applied as a frequency-domain sequences, e.g. MC-CDMA · CPC title

• H04L2209/24

  Key scheduling, i.e. generating round keys or sub-keys for block encryption · CPC title