JP3035512B2 - Multicarrier signal transmission method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a plurality of subcarriers, converts the signals into narrow-band signals, and transmits the converted signals. And a subcarrier signal transmission method and apparatus. The subcarrier signal transmission method and apparatus of the present invention are particularly effective for a large-capacity multi-level modulation scheme.

[0002]

2. Description of the Related Art Some multicarrier signal transmission apparatuses employ a subcarrier selection method in which a plurality of subcarriers having good transmission conditions are selected and used from among a plurality of subcarriers.

FIG. 6 shows a configuration example of a conventional multicarrier signal transmission apparatus to which a subcarrier selection method is applied. In the figure, a multi-carrier signal transmission device includes a transmitting device and a receiving device.

In the transmitting apparatus, a transmission bit sequence A2 is input to a serial / parallel conversion means 10, converted into a parallel signal B2 consisting of a bit set, and input to a transmission-side designated subcarrier selection means 20. The transmission-side designated subcarrier selection unit 20 selects a subcarrier used for transmitting the parallel signal B2 based on the designated subcarrier information signal K2 fed back from the used subcarrier designation unit 90 on the reception side. The subcarriers not selected by the transmission-side designated subcarrier selection means 20 are:
It is used for transmitting an arbitrary dummy bit sequence in order to perform quality measurement on the receiving side. Transmission-side designated subcarrier selection means 20
Is output to the subcarrier signal combining / transmitting means 30, and the transmission signal D2
Becomes

Here, the subcarrier signal combining / transmitting means 30 includes, for example, a serial / parallel conversion circuit and an orthogonal frequency division multiplex (OFDM).
Inverse discrete Fourier transform (I
DFT (Inverse discrete Fourier Transform) circuit (Reference: SBWeinstein et al., "Da
ta transmission by frequency-division multiplexing
using the discreteFourier transform ", IEEE Trans.
Commun.Technol., Vol.COM-19, pp.628-634, Oct. 197
1).

[0006] In the receiving side device, the transmission signal D2 is input to the multicarrier signal receiving / separating means 40 and separated into each subcarrier signal E2. The multicarrier signal receiving / separating means 40 is a DFT (discrete four
ier Transform) circuit.

[0007] The subcarrier signal E2 is input to the receiving-side designated subcarrier selecting means 50 and the subcarrier signal quality measuring means 80. The receiving-side designated subcarrier selecting means 50 selects a subcarrier signal to be received from the subcarrier signal E2 based on the designated subcarrier information signal K2 sent from the used subcarrier specifying means 90 to the transmitting side. Further, the subcarrier signal quality measuring means 80 measures the quality of each subcarrier and gives the measurement result information J2 to the used subcarrier specifying means 90. The used subcarrier designating means 90 designates a predetermined number of subcarriers for signal transmission based on the measurement result information J2, and designates the designated subcarrier information signal K2 to the transmitting side designated subcarrier selecting means 20 and the receiving side. It is transmitted to the designated subcarrier selection means 50.

[0008] The subcarrier signal F2 output from the receiving side designated subcarrier selection means 50 is detected by the detection means 60 and input to the parallel-serial conversion means 70 as a demodulated signal G2. The signal is converted to a signal H2. It should be noted that delay detection or synchronous detection can be used as the detection method.

[0009]

By the way, in the subcarrier selection system in the conventional multicarrier signal transmission apparatus, the quality of all the received subcarrier signals is measured, and the subcarrier to be used is selected from the measured quality. .
For this reason, with an increase in the number of subcarriers, the circuit scale for selecting subcarriers increases, which may make implementation difficult. On the other hand, from the viewpoint of power consumption, a reduction in circuit scale is required.

[0010] It is an object of the present invention to provide a multicarrier signal transmission method and apparatus capable of minimizing an increase in the circuit scale related to subcarrier selection even when the number of subcarriers increases.

[0011]

SUMMARY OF THE INVENTION A multicarrier signal transmission method and apparatus of the present invention divides all selectable subcarriers into a plurality of groups such that the intersubcarrier frequency spacing is maximized. Then, when selecting the subcarrier to be used, the subcarrier to be used is specified for each group. By grouping in this way, the number of subcarriers to be compared at one time can be reduced.
Further, even when the number of all subcarriers increases, it can be dealt with by increasing the number of groups.

[0012]

FIG. 1 shows an embodiment of a multicarrier signal transmission apparatus according to the present invention. In the figure, a serial-parallel conversion means 10 and a subcarrier signal synthesizing / transmitting means 30 of a transmitting apparatus, a multicarrier signal receiving / separating means 40, a detecting means 60 of a receiving apparatus, a parallel / parallel
The serial conversion means 70 and the subcarrier signal quality measurement means 80 are the same as the conventional one shown in FIG.

In the present embodiment, a subgroup selection unit 21 for each transmission side group is provided in place of the conventional subcarrier selection unit 20 for transmission side. Each sub-carrier specifying unit 51 and the sub-carrier specifying unit 9 instead of the conventional sub-carrier specifying unit 90
1 is provided.

[0014] Subcarrier selection means 2 for each transmission side group
1 is a subcarrier designating means 9 for each group used on the receiving side.
Based on the group-specific designated subcarrier information signal K1 fed back from 1, the subcarriers used for transmitting the parallel signal B1 output from the serial / parallel conversion means 10 are selected for each of the N / M groups by L waves. .

Here, as shown in FIG. 2, the number of all subcarriers is N, and the number of subcarriers in each group is M.
Grouping is performed so that the frequency interval between subcarriers in each group is maximized. The purpose is to provide a correlation between the amount of delay of a delayed wave (reflected wave) and the frequency interval of subcarriers in a mobile communication propagation environment as shown in FIG. This is to increase the frequency interval between subcarriers and enhance the effect of selective transmission of subcarriers.

Based on the subcarrier information signal K1 for each group transmitted to the transmitting side from the subcarrier specification unit 91 for each group on the receiving side, the subcarrier selection unit for each group 51 receives N / M subcarrier signals from the subcarrier signal E1. A subcarrier signal to be received by L wave is selected for each group.

Use subcarrier designating means 91 for each group
Specifies an L-wave subcarrier for signal transmission for each group of M-wave subcarriers based on the measurement result information J1 of the subcarrier signal quality measuring means 80, and specifies the group-specific subcarrier information signal K1 is transmitted to the transmission-side group-specific subcarrier selection means 21 and the reception-side group-specific subcarrier selection means 51.

FIG. 3 shows an operation example of the group-specific subcarrier specifying means 91 and the transmitting-side group-specific subcarrier selecting means 21. Here, the total number of subcarriers N is
12, the number of subcarriers M in each group is 4, the number of groups N / M is 3, the number of subcarriers L selected for each group
Shows the case of 2. In the figure, the notation in parentheses is (group number, subcarrier number in group), and (1,
There are 12 subcarriers 1) to (3, 4), and the received power of each is measured by the subcarrier signal quality measuring means 80.

Subcarrier designation means 91 for each group
Specifies the two subcarriers from the one with the larger received power of the subcarrier for each group. here,
(1,1), (1,2), (2,2), (2,3),
The subcarriers (3, 1) and (3, 3) are designated.
In the transmission side group designated subcarrier selection means 21,
Select this specified subcarrier and select the parallel signal B
1 for transmission. Similarly, the designated subcarrier selection means 51 for each receiving side selects the designated subcarrier signal from the subcarrier signal E1.

FIG. 5 shows an example of a simulation result of the cell error rate in the multicarrier signal transmission apparatus of the present invention. Here, the total number of subcarriers N is 32, the number of subcarriers M in each group is 4, the number of groups N / M is 8,
The number of subcarriers L selected for each group is 2, and the cell error rate in a Rayleigh fading channel is obtained in a case where differential detection is applied. Note that the subcarrier signal quality measuring means measures the received power of each subcarrier.

As shown in FIG. 5, by using the apparatus of the present invention, a significant circuit can be obtained by using a simple circuit for selecting, for example, two sub-carriers having high power among four sub-carriers constituting a group. It can be seen that the error rate characteristics can be improved.

[0022]

As described above, the multicarrier signal transmission method and apparatus of the present invention can reduce the number of subcarriers to be compared at one time by grouping when selecting subcarriers to be used. It is possible to suppress the circuit scale related to the subcarrier selection.

Further, even if the total number of subcarriers is increased, if the number of groups is increased, an increase in the circuit scale related to subcarrier selection can be minimized. Further, if the grouping is performed so that the frequency interval between subcarriers is maximized, the correlation between the subcarriers selected for each group can be suppressed low, and the deterioration of the error rate characteristic due to the grouping is minimized. I can do it.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a multicarrier signal transmission device of the present invention.

FIG. 2 is a diagram illustrating subcarrier grouping.

FIG. 3 is a diagram illustrating an operation example of a group-specific subcarrier specifying unit 91 and a transmitting-side group-specific subcarrier selecting unit 21;

FIG. 4 is a diagram showing a correlation between a delay amount of a delayed wave (reflected wave) and a frequency interval of a subcarrier.

FIG. 5 is a diagram showing a cell error rate in the multicarrier signal transmission device of the present invention.

FIG. 6 is a block diagram showing a configuration example of a conventional multicarrier signal transmission device to which a subcarrier selection method is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Serial-parallel conversion means 20 Transmission side designated subcarrier selection means 21 Transmission side group designated subcarrier selection means 30 Subcarrier signal synthesis / transmission means 40 Multicarrier signal reception / separation means 50 Reception side designated subcarrier selection means 51 Reception Sub-group designated sub-carrier selecting means 60 detecting means 70 parallel-serial converting means 80 sub-carrier signal quality measuring means 90 used sub-carrier specifying means 91 used sub-carrier specifying means per group

Continuation of front page (56) References JP-A-11-55206 (JP, A) JP-A-8-316932 (JP, A) JP-A-6-232871 (JP, A) (58) Fields studied (Int) .Cl. ⁷ , DB name) H04J 11/00 H04J 1/00

Claims (5)

(57) [Claims] 1. A multi-carrier signal transmission method for selecting a sub-carrier having a good transmission state from a plurality of sub-carriers as a sub-carrier used for signal transmission, wherein N-wave (N is an integer of 4 or more) sub-carriers Among them, N / M groups are generated by combining M waves (M is an integer of 2 or more), and M waves to L waves (L is 1
A multi-carrier signal transmission method, wherein sub-carriers of an integer not smaller than M are selected. 2. The multi-carrier signal transmission method according to claim 1, wherein when N sub-carriers are grouped by M-waves, the sub-carriers are combined so that the frequency interval between the sub-carriers is maximized for each group. A multicarrier signal transmission method characterized by the above-mentioned. 3. A serial-to-parallel converter for serial-to-parallel conversion of a transmission bit sequence, and a subcarrier used for transmitting a parallel signal output from the serial-to-parallel converter is selected based on designated subcarrier information. Transmitting side designated subcarrier selecting means; subcarrier signal combining / transmitting means for combining the subcarrier signals output from the transmitting side designated subcarrier selecting means to generate a transmission signal; Multicarrier signal receiving / separating means for separating into carrier signals, and a receiving-side designated subcarrier selection for selecting a subcarrier signal based on the designated subcarrier information from each subcarrier signal output from the multicarrier signal receiving / separating means Means output from the receiving-side designated subcarrier selecting means. Detection means for detecting a subcarrier signal; parallel / serial conversion means for converting a demodulated signal output from the detection means into a serial signal similar to the transmission bit sequence; output from the multicarrier signal reception / separation means Subcarrier signal quality measuring means for measuring the quality of each subcarrier signal, and specifying a subcarrier to be used for signal transmission based on the measurement result of the subcarrier signal quality measuring means, and transmitting the specified subcarrier information In a multicarrier signal transmission apparatus comprising a side-designated subcarrier selecting means and a used subcarrier designating means to be transmitted to the receiving-side designated subcarrier selecting means, among N-wave (N is an integer of 4 or more) subcarriers, Generating N / M groups in which M waves (M is an integer of 2 or more) are combined and used The subcarrier designating means designates an L wave (L is an integer of 1 or more and M or less) subcarrier for each group of M wave subcarriers based on the measurement result of the subcarrier signal quality measuring means, The transmitting side designated subcarrier selection means outputs the designated subcarrier information for each group based on the designated subcarrier information for each group, from the M wave to the L wave for each of the N / M groups. A subcarrier selection unit for selecting a subcarrier to be used for signal transmission, wherein the reception-side designated subcarrier selection unit receives L waves from M waves for each of the N / M groups based on the group-specific designated subcarrier information. A multi-carrier signal transmission device having a configuration for selecting a sub-carrier signal to be transmitted. 4. The multi-carrier signal transmission apparatus according to claim 3, wherein when N sub-carriers are grouped by M-waves, the sub-carriers are combined so that the frequency interval between the sub-carriers is maximized for each group. A multicarrier signal transmission device characterized by the above-mentioned. 5. The multi-carrier signal transmission device according to claim 3, wherein the sub-carrier signal quality measuring means is configured to measure the reception power of each sub-carrier signal, and the sub-carrier designation means is used. A multicarrier signal characterized by designating L wave subcarriers in descending order of received power for each group of M wave subcarriers based on the measurement result of the subcarrier signal quality measurement means. Transmission equipment.