Methods and systems for transmitting an information signal in a multiple antenna communication system
View Patent ↗Methods and systems are provided for transmitting a plurality of information signals in a multiple antenna communication system. One or more information signals are coded using a plurality of coders to generate the plurality of coded information signals and an Inverse Fast Fourier Transformation is performed on each of the plurality of coded information signals to create a corresponding output signal. Each of the corresponding output signals are transmitted on a different antenna. Each of the plurality of coded information signals can optionally be separated into K signals. On the receiver side, a signal comprising K different frequencies is received on at least N receive antennas and a Fast Fourier Transformation is applied to each of the at least N received versions of the signal comprising K different frequencies to generate N*K low frequency signals. The N*K separate low frequency signals are then combined to recover a transmitted information signal, based on one or more transfer functions from each of a plurality of transmit antennas to each of the N receive antennas.
1. A method for obtaining a transfer function in a wireless communication system, comprising the steps of:
suppressing transmission on all antennas of a first set of transmitters and all except one antenna of a second set of transmitters;
transmitting a calibration signal from said excepted one antenna of said second set of transmitters; and
measuring said transmitted calibration signal to generate a transfer function h ij (i=1, 2, . . . , N; j=1, 2, . . . , M) of radiofrequency signal paths between said excepted one antenna of said second set of transmitters and an antenna of one or more receivers.
2. The method of claim 1 , wherein said steps are repeated for each antenna of said second set of transmitters.
3. The method of claim 1 , wherein said steps are repeated for each antenna of said one or more receivers.
4. A method for receiving information in a wireless radiofrequency OFDM communication system, comprising the steps of:
receiving signals V RF i (i=1, 2, . . . , N) transmitted from a first set of transmitters;
removing a radiofrequency carrier from said received signals V RF i to obtain signals V C i (i=1, 2, . . . , N), wherein V C i comprises K different frequencies;
performing a Fast Fourier Transform on each signal V C i (i=, 1, 2, . . . , N) to output K separate low-frequency signals [v il , . . . , v iK ];
processing said K*N output signals v ik (i=1, 2, . . . , N; k=1, 2, . . . , K), wherein each of a set of least squares estimation units receives N input signals v ik (i=1, 2, . . . , N) and wherein an output of each least squares unit consists of M estimation signals;
combining said N*M estimation signals to create a signal S_est j =[s_est jl , . . . , s_est jK ], wherein s_est jk is an estimation signal for transmitted signals s c jk ; and
demodulating said low-frequency signal S_est j to yield a signal S D _est j , wherein said signal S D _est j is approximately equal to S j , j=1, . . . , M, wherein S j comprises M simultaneous communication channels.
5. The method of claim 4 , wherein a symbol interval is cyclically extended with a guard interval that is larger than an associated delay spread.
6. The method of claim 4 , wherein said combining step further comprises the step of parallel to serial conversion.
7. A method for transmitting a plurality of information signals in a multiple antenna communication system, comprising the steps of:
coding one or more information signals using a plurality of coders to generate said plurality of coded information signals;
performing an Inverse Fast Fourier Transformation on each of said plurality of coded information signals to create a corresponding output signal; and
transmitting each of said corresponding output signals on a different antenna.
8. The method of claim 7 , further comprising the step of separating each of said plurality of coded information signals into K signals.
9. The method of claim 7 , wherein a receiver processes a received version of one or more of said corresponding output signals based on transfer functions from each of a plurality of transmit antennas to each of a plurality of receive antennas.
10. The method of claim 9 , wherein said transfer functions are determined by a geometry of a configuration of the multiple antenna communication system, wherein each of said transfer functions is associated with a different travel-path between an antenna of a first set of transmitters and an antenna of a receiver.
11. The method of claim 9 , wherein said transfer functions H are expressed as a complex number, wherein an amplitude of one of said complex numbers is an attenuation of a strength of a signal and wherein a phase of one of said complex numbers is a phase modulation incurred during transmission along a travel path.
12. The method of claim 7 , wherein said communication system is an OFDM communication system.
13. The method of claim 7 , further comprising the step of applying a Forward Error Correction to at least one of said information signals.
14. A mobile station for transmitting a plurality of information signals in a multiple antenna communication system, comprising:
a plurality of coders for generating a plurality of coded information signals based on said one or more information signals;
an Inverse Fast Fourier Transformation stage for creating a corresponding output signal based on each of said plurality of coded information signals; and
a plurality of antennas, wherein each of said corresponding output signals are transmitted on a different antenna.
15. The mobile station of claim 14 , further comprising a serial-to-parallel unit for separating each of said plurality of coded information signals into K signals.
16. The mobile station of claim 14 , wherein a receiver processes a received version of one or more of said corresponding output signals based on transfer functions from each of a plurality of transmit antennas to each of a plurality of receive antennas.
17. The mobile station of claim 14 , wherein said communication system is an OFDM communication system.
18. The mobile station of claim 14 , further comprising a circuit for applying a Forward Error Correction to at least one of said information signals.