OFDM reception under high adjacent channel interference while preserving frame structure

1. A method for Orthogonal Frequency Division Multiplexing (OFDM) transmission and reception, the method comprising:

receiving, at a Hann receiver, a CP-OFDM symbol comprising a cyclic prefix (CP);

removing the cyclic prefix from the received CP-OFDM symbol to generate an OFDM symbol;

applying a Hann window to the OFDM symbol to obtain a Hann windowed OFDM symbol, wherein applying the Hann window introduces inter-carrier interference (ICI) into the OFDM symbol;

applying Fast Fourier Transformation (FFT) to the Hann windowed OFDM symbol to obtain a plurality of frequency domain subcarriers;

applying multiple access (MA) subcarrier demapping to the plurality of frequency domain subcarriers to obtain a plurality of MA demapped frequency domain subcarriers;

receiving, at the Hann receiver, a transmitted pilot sequence comprising a plurality of frequency domain pilot symbols;

filtering the plurality of frequency domain pilot symbols of the transmitted pilot sequence to obtain an observed pilot sequence;

performing channel estimation based upon the observed pilot sequence to estimate the ICI introduced into the OFDM symbols by the application of the Hann window;

cancelling the ICI from the plurality of MA demapped frequency domain subcarriers based upon the channel estimation, wherein applying maximum ratio combining (MRC) and soft decision turbo successive interference cancellation (SIC) structure are applied at the Hann receiver to perform channel equalization and the ICI estimation and cancellation; and

applying demodulation to the MA demapped subcarriers to recover the desired signal.

2. The method of claim 1 , wherein the plurality of MA demapped subcarriers of the CP-OFDM symbol are π/2-binary phase shift keying (BPSK) modulated and wherein applying demodulation further comprises, applying π/2-BPSK demodulation to the plurality of MA demapped subcarriers.

3. The method of claim 1 , wherein the plurality of MA demapped subcarriers of CP-OFDM symbol are Quadrature Amplitude Modulated (QAM) CP-OFDM and wherein applying demodulation further comprises, applying QAM demodulation to the plurality of MA demapped subcarriers.

4. The method of claim 1 , wherein the plurality of MA demapped subcarriers of the CP-OFDM symbols are π/2-amplitude shift keying (ASK) modulated and transmitted over a multiple access channel prior to being received at the Hann receiver and wherein the method further comprises applying a π/2 rotation to the ASK modulated symbols to generate π/2-ASK modulated symbols at a transmitter.

5. The method of claim 4 , further comprising:

applying multiple access (MA) subcarrier mapping to the plurality of π/2-ASK modulated symbols at the transmitter to generate an MA subcarrier mapped plurality of π/2-ASK modulated symbols;

applying Inverse Fast Fourier Transformation to the MA subcarrier mapped plurality of π/2-ASK modulated symbols at the transmitter to generate a time-domain OFDM symbol consisting of MA subcarrier mapped plurality of π/2-ASK modulated symbols; and

adding a cyclic prefix (CP) to the time-domain OFDM symbol consisting of MA subcarrier mapped plurality of π/2-ASK modulated symbols at the transmitter to generate the time-domain CP-OFDM symbol consisting of MA subcarrier mapped plurality of π/2-ASK modulated symbols.

6. The method of claim 4 , further comprising, applying −π/2 rotation to the plurality of subcarriers received at the Hann receiver.

7. A method for Orthogonal Frequency Division Multiplexing (OFDM) transmission and reception, the method comprising:

performing amplitude shift keying (ASK) modulation of bits at a transmitter, the ASK modulated bits to be transmitted to a receiver over a multiple access channel;

applying π/2-rotation to the ASK modulated symbols to generate π/2-MASK modulated symbols;

applying multiple access mapping to the π/2-MASK modulated symbols to shape the symbols into multiple access (MA) OFDM data subcarriers;

performing Inverse Fast Fourier Transformation (IFFT) on the OFDM data subcarriers to generate the OFDM waveforms;

adding a cyclic prefix to the OFDM waveforms before transmission over the multiple access channel;

introducing a channel impulse response (CIR) and adjacent channel interference (ACI) into the OFDM waveforms during transmission over the channel;

receiving the OFDM waveforms at a Hann receiver;

performing Hann windowing of the received OFDM waveforms;

performing Fast Fourier Transformation (FFT) and multiple access subcarrier demapping to obtain frequency domain symbols of a desired user;

estimating the channel; and

equalizing the frequency domain symbols using the channel estimates;

applying −π/2 rotation to the equalized frequency domain symbols and ASK demodulation to the symbols to recover desired bits.

8. A system for improving Orthogonal Frequency Division Multiplexing (OFDM) reception, the system comprising:

a Hann receiver for;

receiving, at a Hann receiver, a CP-OFDM symbol comprising a cyclic prefix (CP);

removing the cyclic prefix from the received CP-OFDM symbol to generate an OFDM symbol;

applying a Hann window to the OFDM symbol to obtain a Hann windowed OFDM symbol, wherein applying the Hann window introduces inter-carrier interference (ICI) into the OFDM symbol;

applying Fast Fourier Transformation (FFT) to the Hann windowed OFDM symbol to obtain a plurality of frequency domain subcarriers;

applying multiple access (MA) subcarrier demapping to the plurality of frequency domain subcarriers to obtain a plurality of MA demapped frequency domain subcarriers;

receiving a transmitted pilot sequence comprising a plurality of frequency domain pilot symbols;

filtering the plurality of frequency domain pilot symbols of the transmitted pilot sequence to obtain an observed pilot sequence;

performing channel estimation based upon the observed pilot sequence to estimate the ICI introduced into the OFDM symbols by the application of the Hann window;

cancelling the ICI from the plurality of MA demapped frequency domain subcarriers based upon the channel estimation, wherein applying maximum ratio combining (MRC) and soft decision turbo successive interference cancellation (SIC) structure are applied at the Hann receiver to perform channel equalization and the ICI estimation and cancellation; and

applying demodulation to the MA demapped subcarriers to recover the desired signal.

9. The method of claim 8 , wherein the plurality of MA demapped subcarriers of the CP-OFDM symbol are π/2-binary phase shift keying (BPSK) modulated and wherein applying demodulation further comprises, applying π/2-BPSK demodulation to the plurality of MA demapped subcarriers.

10. The method of claim 1 , wherein the plurality of MA demapped subcarriers of CP-OFDM symbol are Quadrature Amplitude Modulated (QAM) CP-OFDM and wherein applying demodulation further comprises, applying QAM demodulation to the plurality of MA demapped subcarriers.

11. The system of claim 8 , wherein the plurality of MA demapped subcarriers are amplitude shift keying (ASK) modulated and wherein the system further comprises:

a transmitter for applying π/2 rotation to the plurality of ASK modulated symbols; and

the receiver is further for applying −π/2 rotation at the Hann receiver.

12. A computer program product comprising computer executable instructions embodied in a non-transitory computer-readable medium for performing steps comprising, receiving, at a Hann receiver, a CP-OFDM symbol comprising a cyclic prefix (CP), removing the cyclic prefix from the received CP-OFDM symbol to generate an Orthogonal Frequency Division Multiplexing (OFDM) symbol, applying a Hann window to the OFDM symbol to obtain a Hann windowed OFDM symbol, wherein applying the Hann Window introduces inter-carrier interference (ICI) into the OFDM symbol, applying a Fast Fourier Transformation (FFT) to the Hann windowed OFDM symbol to obtain a plurality of subcarriers, applying multiple access (MA) subcarrier demapping to the plurality of frequency domain subcarriers to obtain a plurality of MA demapped frequency domain subcarriers, receiving a transmitted pilot sequence comprising a plurality of frequency domain pilot symbols, filtering the plurality of frequency domain pilot symbols of the transmitted pilot sequence to obtain an observed pilot sequence, performing channel estimation based upon the observed pilot sequence to estimate the ICI introduced into the OFDM symbols by the application of the Hann window and cancelling the ICI from the plurality of MA demapped frequency domain subcarriers based upon the channel estimation, wherein applying maximum ratio combining (MRC) and soft decision turbo successive interference cancellation (SIC) structure are applied at the Hann receiver to perform channel equalization and the ICI estimation and cancellation and applying demodulation to the MA demapped subcarriers to recover the desired signal.

13. The computer program product of claim 12 , wherein the CP-OFDM symbol comprises a plurality of multiple access (MA) mapped subcarriers modulated by π/2-binary phase shift keying (BPSK).