Data transmission method and radio system
AssigneeNokia Corporation
InventorMikko Kokkonen
Life of this patent
Estimating the term…
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.
Claims10
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:
- fn=(afn−1+b)mod N,
- where a and b are constants, N is a maximum amount of carriers in the band in use, fn is a determining reference number of a desired reference carrier and fn−1 is a determining reference number of the desired reference carrier formed during previous iteration and as an initial value the reference number fn−1 has a freely selected value.
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.
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:
- fn=(afn−1+b)mod N,
- where a and b are constants, N is a total amount of reference carriers in the band in use, fn is a reference number determining the frequency of a desired reference carrier and fn−1 is a reference number determining the frequency of the desired reference carrier formed during previous iteration and an initial value for the reference number fn−1 can be freely selected.
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.
Dependencies are inferred from the claim text.