Data transmission method and radio system

• US 6,606,296 B1
• Filed: 06/29/1999
• Issued: 08/12/2003
• Est. Priority Date: 01/16/1997
• Status: Expired due to Term

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Kokkonen, Mikko
• Primary Examiner(s): Vo, Nguyen T.
• Assistant Examiner(s): LEE, JOHN J
• Application Number:
  US09/331,936
• Time in Patent Office: 1,505 Days
• Field of Search: 370/203, 370/204, 370/208, 370/210, 370/343, 370/344, 370/206, 375/325, 375/150, 375/130
• US Class Current: 370/203
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 27/2662 Symbol synchronisation
• CPC Class Codes: H04L 5/0016 Time-frequency-code
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver

Abstract

The invention relates to a data transmission method and a radio system comprising at least one base station and a subscriber terminal. In this method each transmitter places reference carriers by an OFDMA moldulator in a band in use substantially randomly, whereby a receiver can use the reference carrier signal for synchronization.

Claims

1. A data transmission method used in a radio system comprising at least one base station (1) and a subscriber terminal (2-4) which modulate a signal to be transmitted on subcarriers of an orthogonal multicarrier modulation and transmit a reference signal (6-8) in a band in use by using reference carriers formed by the multicarrier modulation, characterized in that

the reference carriers are substantially randomly placed in the band in use;

the reference carriers have a reference number; and

the reference carriers are placed in the band in use by using a linear congruential generation formula based on iteration;

2. A method as claimed in claim 1, characterized in that the reference carriers are evenly placed in the band in use.

3. A method as claimed in claim 1, characterized in that the reference carriers have a reference number and

the reference carriers are selected for the band in use by using an M sequence in such a manner that the predetermined consecutive bits of the M sequence form a determining reference number of the reference carrier.

4. A method as claimed in claim 1, characterized in that the reference carriers are frequency hopped.

5. A data transmission method used in a radio system comprising at least one base station (1) and a subscriber terminal (2-4) which modulate a signal to be transmitted on subcarriers of an orthogonal multicarrier modulation and transmit a reference signal (6-8) in a band in use by using reference carriers formed by the multicarrier modulation, characterized in that

the reference carriers are substantially randomly placed in the band in use;

when an OFDM signal comprising a predetermined reference symbol is transmitted on, the reference carriers the channel estimate is formed by calculating a correlation between a symbol of the received OFDM signal and the predetermined reference symbol, by thresholding the correlation and by calculating a Fourier transform from the thresholded correlation, and

the correlation is calculated by Fourier transforming the received OFDM signal symbol and the reference symbol, by multiplying the Fourier-transformed received symbol of the reference carriers and the reference symbol with one another, and by inverse Fourier transforming the Fourier-transformed and multiplied received symbol of the reference carriers and the reference symbol.

6. A radio system comprising at least one base station and a subscriber terminal comprising a transmitter (30) and a receiver (31) arranged to modulate a signal to be transmitted on subcarriers using orthogonal multicarrier modulation and to transmit and receive a reference signal which is multicarrier modulated on reference carriers, characterized in that

the transmitter (30) of the radio system is arranged to substantially randomly place the reference carriers into a band in use;

the reference carriers have a reference number; and

the transmitter (30) is arranged to place the reference carriers in the band in use by using a linear congruential generation formula based on iteration;

7. A radio system as claimed in claim 6, characterized in that the transmitter (30) is arranged to place the reference carriers evenly in the band in use.

8. A radio system as claimed in claim 6, characterized in that the reference carriers have a reference number and

the transmitter (30) is arranged to place the reference carriers in the band in use by using an M sequence in such a manner that the predetermined consecutive bits of the M sequence form the reference number determining the frequency of the reference carrier.

9. A radio system as claimed in claim 6, characterized in that the transmitter (30) is arranged to frequency hop the reference carriers.

10. A radio system comprising at least one base station and a subscriber terminal comprising a transmitter (30) and a receiver (31) arranged to modulate a signal to be transmitted on subcarriers using orthogonal multicarrier modulation and to transmit and receive a reference signal which is multicarrier modulated on reference carriers, characterized in that

the transmitter (30) of the radio system is arranged to substantially randomly place the reference carriers into a band in use;

the receiver (31) is arranged to form a channel estimate of the subcarriers utilizing the reference carriers for coherent detection;

when the transmitter (30) transmits an OFDM signal comprising a predetermined reference symbol on the reference carriers the receiver (31) is arranged to form the channel estimate by calculating a correlation between the received OFDM signal symbol and the reference symbol, by thresholding the correlation and by calculating a Fourier transform from the thresholded correlation; and

the receiver (31) is arranged to calculate the correlation by Fourier-transforming the OFDM signal symbol and the reference symbol by multiplying the Fourier-transformed reference carrier symbol and the reference symbol with one another, and by inverse Fourier transforming the Fourier-transformed and multiplied reference carrier symbol and the reference symbol.