Method and system for combining DFT-transformed OFDM and non-transformed OFDM
Methods and systems are provided that enable an OFDM transmitter to be used for transmitting conventional OFDM or a form of transformed OFDM. A technique is provided for transforming a coded and modulated sequence of samples prior to an IFFT that enables the transformed sequence of samples to be transmitted using conventional OFDM or transformed OFDM. The selection of a transform function for transforming the coded and modulated sequence of samples may be based on optimizing the transform function for particular operating conditions between the transmitter and receiver. In some embodiments of the invention OFDM and time transformed OFDM are multiplexed in time and/or frequency in a transmission frame. In some embodiments of the invention a pilot pattern is provided in which the pilot are sent using OFDM and data is sent using OFDM and/or transformed OFDM.
1. An apparatus, comprising:
a baseband processor coupled to transmit circuitry and at least one antenna, wherein the baseband processor is configured to:
apply a discrete Fourier transform (DFT) transformation to a first plurality of symbols conforming to a first traffic type to obtain an intermediate set of symbols, wherein the first plurality of symbols have undergone coding and modulation;
perform an inverse Fast Fourier transform (IFFT) on a first mapped set of symbols corresponding to the intermediate set of symbols to produce a set of uplink single carrier frequency division multiple access (FDMA) signals;
transmit the set of uplink single carrier FDMA signals to the transmit circuitry for transmission via the at least one antenna;
perform an inverse Fast Fourier transform (IFFT) on a second mapped set of symbols corresponding to a second plurality of symbols conforming to a second traffic type to generate uplink non-transformed OFDM signals, wherein the second plurality of symbols have undergone coding and modulation, wherein, in generating the non-transformed OFDM signals, the baseband processor does not apply a DFT transformation; wherein the non-transformed OFDM signals are multi-carrier code division multiple access MC-CDMA signals, wherein a group of user equipment devices transmit MC-CDMA signals using respective spreading codes, wherein the spreading codes are applied in at least the frequency direction; and
transmit the MC-CDMA signals to the transmit circuitry for transmission via the at least one antenna.
2. The apparatus of claim 1 , wherein the MC-CDMA signals include a cluster, wherein the cluster is a set of contiguous subcarriers crossing as a set of OFDM symbols.
3. The apparatus of claim 1 , wherein the MC-CDMA signals are a group of two clusters.
4. The apparatus of claim 1 , wherein set of uplink single carrier FDMA signals are localized FDMA signals.
5. The apparatus of claim 1 , wherein set of uplink single carrier FDMA signals are distributed FDMA signals, where the set of uplink single carrier FDMA signals includes a plurality of sub-bands.
6. The apparatus of claim 1 , wherein the first traffic comprises voice channel information.
7. The apparatus of claim 1 , wherein there are N spreading codes and N user equipment devices in the group, where N is an integer greater than one.
8. A method, comprising:
at a wireless node:
applying a discrete Fourier transform (DFT) transformation to a first plurality of symbols conforming to a first traffic type to obtain an intermediate set of symbols, wherein the first plurality of symbols have undergone coding and modulation;
performing an inverse Fast Fourier transform (IFFT) on a first mapped set of symbols corresponding to the intermediate set of symbols to produce a set of uplink single carrier frequency division multiple access (FDMA) signals;
transmitting the set of uplink single carrier FDMA signals;
performing an inverse Fast Fourier transform (IFFT) on a second mapped set of symbols corresponding to a second plurality of symbols conforming to a second traffic type to generate uplink non-transformed OFDM signals, wherein the second plurality of symbols have undergone coding and modulation, wherein, in generating the non-transformed OFDM signals, the baseband processor does not apply a DFT transformation; wherein the non-transformed OFDM signals are multi-carrier code division multiple access MC-CDMA signals, wherein a group of user equipment devices transmit MC-CDMA signals using respective spreading codes, wherein the spreading codes are applied in at least the frequency direction; and
transmitting the MC-CDMA signals.
9. The method of claim 8 , wherein the MC-CDMA signals include a cluster, wherein the cluster is a set of contiguous subcarriers crossing as a set of OFDM symbols.
10. The method of claim 8 , wherein the MC-CDMA signals are a group of two clusters.
11. The method of claim 8 , wherein set of uplink single carrier FDMA signals are localized FDMA signals.
12. The method of claim 8 , wherein set of uplink single carrier FDMA signals are distributed FDMA signals, where the set of uplink single carrier FDMA signals includes a plurality of sub-bands.
13. The method of claim 8 , wherein the first traffic comprises voice channel information.
14. An apparatus, comprising:
a baseband processor coupled to transmit circuitry and at least one antenna, wherein the baseband processor is configured to:
apply a discrete Fourier transform (DFT) transformation to a first plurality of symbols conforming to a first traffic type to obtain an intermediate set of symbols, wherein the first plurality of symbols have undergone modulation;
perform an inverse Fast Fourier transform (IFFT) on a first mapped set of symbols corresponding to the intermediate set of symbols to produce a set of uplink single carrier frequency division multiple access (FDMA) signals;
transmit the set of uplink single carrier FDMA signals to the transmit circuitry for transmission via the at least one antenna;
perform an inverse Fast Fourier transform (IFFT) on a second mapped set of symbols corresponding to a second plurality of symbols conforming to a second traffic type to generate uplink non-transformed OFDM signals, wherein the second plurality of symbols have undergone modulation, wherein, in generating the non-transformed OFDM signals, the baseband processor does not apply a DFT transformation; wherein the non-transformed OFDM signals are multi-carrier code division multiple access MC-CDMA signals, wherein a group of user equipment devices transmit MC-CDMA signals using respective spreading codes, wherein the spreading codes are applied in at least the frequency direction; and
transmit the MC-CDMA signals to the transmit circuitry for transmission via the at least one antenna, wherein the set of uplink single carrier FDMA signals and the MC-CDMA signals are transmitted simultaneously during at least one single carrier FDMA symbol duration using frequency division multiplexing.
15. The apparatus of claim 14 , wherein the MC-CDMA signals include a cluster, wherein the cluster is a set of contiguous subcarriers crossing as a set of OFDM symbols.
16. The apparatus of claim 14 , wherein the MC-CDMA signals are a group of two clusters.
17. The apparatus of claim 14 , wherein the set of uplink single carrier FDMA signals are localized FDMA signals.
18. The apparatus of claim 14 , wherein the set of uplink single carrier FDMA signals are distributed FDMA signals, where the set of uplink single carrier FDMA signals includes a plurality of sub-bands.
19. The apparatus of claim 14 , wherein the first traffic comprises voice channel information.
20. The apparatus of claim 14 , wherein there are N spreading codes and N user equipment devices in the group, where N is an integer greater than one.