Systems, methods and transceivers or wireless communications over discontiguous spectrum segments
View Patent ↗Methods of transmitting a plurality of communications signals over a plurality of discontiguous bandwidth segments in a frequency band include defining a plurality (N FFT ) of orthogonal subcarriers across the frequency band, defining a plurality (N) of available physical subcarriers from among the orthogonal subcarriers. The available physical subcarriers are distributed among, the plurality of discontiguous bandwidth segments. The methods further include spreading the data symbols for each user and combining the spread data symbols to provide composite data signals. The composite data signals are converted to parallel input signals and interleaved. The interleaved signals are assigned to the N available physical subcarriers. Related transmitters, receivers and communications systems are also disclosed.
1. A method of transmitting a plurality of communications signals over a plurality of discontiguous bandwidth segments in a frequency band, comprising:
defining a plurality (N FFT ) of orthogonal subcarriers across the frequency band;
defining a plurality (N) of available physical subcarriers from among the orthogonal subcarriers, wherein the available physical subcarriers are distributed among the plurality of discontiguous bandwidth segments;
receiving M data symbols for each of K users;
spreading the data symbols of each user by an L-bit spreading code associated with the user to provide M spread data symbols for each of the K users by applying the L-bit spreading code by mapping different chips of the spreading code to the available physical subcarriers over the plurality of discontiguous bandwidth segments;
combining the M spread data symbols associated with each of the K users to provide M composite data signals;
converting the M composite data signals to parallel input signals having a length L;
interleaving the M parallel input signals to provide Q interleaved input signals having a length N;
assigning the Q interleaved input signals to the N available physical subcarriers; and
transmitting the Q interleaved input signals on the N available physical subcarriers.
2. The method of claim 1 , wherein transmitting the Q interleaved input signals on the N available physical subcarriers comprises assigning zeros to N FFT -N unavailable physical subcarriers to provide N FFT input signals and performing an N FFT point inverse fourier transform on the N FFT input signals.
3. The method of claim 1 , wherein a number of chips in the L-bit spreading code is equal to the number N of available physical subcarriers.
4. The method of claim 1 , wherein combining the M spread data symbols associated with each of the K users to provide M composite data signals comprises performing a composite superposition of K chip level subcarrier sequences.
5. The method of claim 1 , wherein spreading the data symbols of each user by the L-bit spreading code comprises spreading the data symbols of each user using user-specific long spreading codes to generate resulting signals.
6. The method of claim 5 , wherein combining the M spread data symbols comprises:
combining the resulting signals with a pilot signal to generate a pilot combined signal; and
spreading the pilot combined signal with a covering code unique to a cell in which the users operate.
7. A transmitter for transmitting a plurality of communications signals over a plurality of discontiguous bandwidth segments in a frequency band, comprising:
a plurality of spreaders configured to spread M data symbols for each of K users according to a corresponding spreading code having length L;
a plurality of combiners configured to combine the spread M data symbols for each of the K users to provide M composite spread signals;
a plurality of serial to parallel converters configured to convert the M composite spread signals to M parallel input signals;
a frequency interleaver configured to interleave the M parallel input signals to provide Q interleaved input signals having a length N;
a subcarrier mapper configured to assign the Q interleaved input signals to N available physical subcarriers; and
an inverse fast fourier transform (IFFT) processor configured to modulate the N available physical subcarriers with the Q interleaved input signals,
wherein each of the spreaders is further configured to apply the corresponding spreading code having length L by mapping different chips of the corresponding spreading code to the available physical subcarriers over the plurality of discontiguous bandwidth segments.
8. The transmitter of claim 7 , wherein the subcarrier mapper is configured to assign zeros to N FFT -N unavailable physical subcarriers to provide N FFT input signals, and wherein the IFFT processor is configured to perform an N FFT point inverse fourier transform on the N FFT input signals.
9. The transmitter of claim 7 , wherein a number of chips in the L-bit spreading code is equal to the number N of available physical subcarriers.
10. The transmitter of claim 7 , wherein each of the combiners is configured to combine the M spread data symbols associated with each of the K users to provide M composite data signals by performing a composite superposition of K chip level subcarrier sequences.
11. The transmitter of claim 7 , wherein each of the spreaders is further configured to spread the data symbols for each of the K users using user-specific long spreading codes to generate resulting signals.
12. The transmitter of claim 11 , wherein each of the plurality of combiners are further configured to:
combine a corresponding one of the resulting signals with a pilot signal to generate a pilot combined signal; and
spread the pilot combined signal with a covering code unique to a cell in which the K users operate.
13. A method of transmitting a plurality of communications signals over a plurality of discontiguous bandwidth segments in a frequency band, comprising:
defining a plurality (N FFT ) of orthogonal subcarriers across the frequency band;
defining a plurality (N) of available physical subcarriers from among the orthogonal subcarriers, wherein the available physical subcarriers are distributed among the plurality of discontiguous bandwidth segments;
receiving M data symbols for each of K users;
spreading the data symbols of each user by an L-bit spreading code associated with the user to provide M spread data symbols for each of the K users;
combining the M spread data symbols associated with each of the K users to provide M composite data signals;
converting the M composite data signals to parallel input signals having a length L;
interleaving the M parallel input signals to provide Q interleaved input signals having a length N;
assigning the Q interleaved input signals to the N available physical subcarriers; and
transmitting the Q interleaved input signals on the N available physical subcarriers,
wherein the plurality of discontiguous bandwidth segments at least partially span two or more spectrum blocks, and
wherein each spectrum block contains at least N physical subcarriers.
14. A method of transmitting a plurality of communications signals over a plurality of discontiguous bandwidth segments in a frequency band, comprising:
defining a plurality (N FFT ) of orthogonal subcarriers across the frequency band;
defining a plurality (N) of available physical subcarriers from among the orthogonal subcarriers wherein the available physical subcarriers are distributed among the plurality of discontiguous bandwidth segments;
receiving M data symbols for each of K users;
spreading the data symbols of each user by an L-bit spreading code associated with the user to provide M spread data symbols for each of the K users;
combining the M spread data symbols associated with each of the K users to provide M composite data signals;
converting the M composite data signals to parallel input signals having a length L;
interleaving the M parallel input signals to provide Q interleaved input signals having a length N;
assigning the Q interleaved input signals to the N available physical subcarriers; and
transmitting Q interleaved input signals on the N available physical subcarriers,
wherein N FFT >N and wherein the N available physical subcarriers are distributed over the plurality of discontiguous bandwidth segments that are separated by interstitial segments that are not available for transmission.
15. The method of claim 1 , wherein the N available physical subcarriers do not include guard subcarriers.
16. A transmitter for transmitting a plurality of communications signals over a plurality of discontiguous bandwidth segments in a frequency band, comprising:
a plurality of spreaders configured to spread M data symbols for each of K users according to a corresponding spreading code having length L;
a plurality of combiners configured to combine the spread M data symbols for each of the K users to provide M composite spread signals;
a plurality of serial to parallel converters configured to convert the M composite spread signals to M parallel input signals;
a frequency interleaver configured to interleave the M parallel input signals to provide Q interleaved input signals having a length N;
a subcarrier mapper configured to assign the Q interleaved input signals to N available physical subcarriers; and
an inverse fast fourier transform (IFFT) processor configured to modulate the N available physical subcarriers with the Q interleaved input signals,
wherein the plurality of discontiguous bandwidth segments at least partially span two or more spectrum blocks, and
wherein each spectrum block contains at least N physical subcarriers.
17. A transmitter for transmitting a plurality of communications signals over a plurality of discontiguous bandwidth segments in a frequency band, comprising:
a plurality of spreaders configured to spread M data symbols for each of K users according to a corresponding spreading code having length L;
a plurality of combiners configured to combine the spread M data symbols for each of the K users to provide M composite spread signals;
a plurality of serial to parallel converters configured to convert the M composite spread signals to M parallel input signals;
a frequency interleaver configured to interleave the M parallel input signals to provide Q interleaved input signals having a length N;
a subcarrier mapper configured to assign the Q interleaved input signals to N available physical subcarriers; and
an inverse fast fourier transform (IFFT) processor configured to modulate the N available physical subcarriers with the Q interleaved input signals,
wherein the subcarrier mapper is configured to assign zeros to N FFT -N unavailable physical subcarriers to provide N FFT input signals, and wherein the IFFT processor is configured to perform an N FFT point inverse fourier transform on the N FFT input signals,
wherein N FFT >N and wherein the N available physical subcarriers are distributed over the plurality of discontiguous bandwidth segments that are separated by interstitial segments that are not available for transmission.