Radio apparatus

• US 20070064591A1
• Filed: 09/19/2006
• Published: 03/22/2007
• Est. Priority Date: 09/21/2005
• Status: Active Grant

• Current Assignee: Hera Wireless S.A. (Fineur International S.A.)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Nakao, Seigo
• Granted Patent: US 8,228,921 B2
• Time in Patent Office: Days
• US Class Current: 370/208
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 27/2605 Symbol extensions, e.g. Zero Tail, Unique Word [UW]
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver

Abstract

A control unit assigns a plurality of data signals in a manner that, of the plurality of data signals, data signals of higher data rate are assigned anteriorly. Of terminal apparatuses to which the plurality of data signals are to be transmitted respectively, the control unit specifies a terminal apparatus to which a training signal is to be transmitted. If the data signal to be sent to the specified terminal apparatus is contained in an anterior part of the packet signal, the control unit will append a training signal to a front part preceding a leading data signal. If the data signal to be sent to the specified terminal apparatus is not contained in an anterior part of the packet signal, the control unit will move this data signal to a posterior part of the packet signal and then append a training signal to a front part preceding this moved data signal.

Claims

1. A radio apparatus, comprising:

an input unit which inputs a plurality of data signals, each data signal being composed of at least one stream;

a generation unit which generates a packet signal by arranging the plurality of data signals in a manner that, among the plurality of data signals inputted in said input unit, a data signal of a higher data rate is assigned in an anterior part;

a specifying unit which specifies a terminal apparatus to which known signals, whose number of streams is greater than that of data signals, are to be transmitted, among terminal apparatuses to which the plurality of data signals contained in the packet signal generated by said generation unit are to be transmitted respectively;

an adding unit including;

a first adding means which appends the known signals, whose number of streams is greater than that of data signals, to a position anterior to a leading data signal when a data signal which is to be transmitted to the terminal apparatus specified by said specifying unit is contained in an anterior part of the packet signal generated by said generation unit; and

,

a second adding means which moves a data signal to a posterior part of the packet signal and then appends a known signal, whose number of streams is greater than that of data signals, to an anterior part preceding the moved data signal and which appends known signals, whose number of streams corresponds to the number of data signals, to a position anterior to the leading data signal when the data signal which is to be transmitted to the terminal apparatus specified by said specifying unit is not contained in the anterior part of the packet signal generated by said generation unit; and

a transmitter which transmits a packet signal to which the known signal has been appended by said adding unit.

2. A radio apparatus according to claim 1, wherein said generation unit is such that

a data signal of a higher data rate is assigned to an anterior part of packet signal, and

a data signal of a lower data rate is assigned toward a posterior part of packet signal.

3. A radio apparatus according to claim 1, wherein at the time of generating the packet signal said generation unit appends control signals, indicating a terminal apparatus that should transmit a data signal, to the plurality of signal data, respectively.

4. A radio apparatus according to claim 1, further comprising a receiving unit which receives a request indicating that a known signal, whose number of streams is greater than that of data signals, needs to be transmitted,

wherein said specifying unit specifies a terminal apparatus corresponding to the request received by said receiving unit.

5. A radio apparatus according to claim 1, wherein said specifying unit specifies a terminal apparatus which has not received information on data rate over a certain period of time, and

wherein when appending the known signal, whose number of streams is greater than that of data signals, to the data signals which are to be transmitted to the terminal apparatus specified by said specifying apparatus, said adding unit appends a request indicating that the information on data rate needs to be transmitted.

6. A radio apparatus according to claim 1, wherein when appending known signals, whose number of streams is greater than that of data signals, said adding unit appends the known signals to a main stream where a data signal is assigned and a sub-stream where no data signal, respectively, and assigns a known signal in the sub-stream to a timing other than a timing to which a data signal and a known signal in the main stream are assigned.

7. A radio apparatus according to claim 6, wherein said adding unit is such that

using a known signal, as a reference, assigned to one of main streams, a cyclic timing shift within a known signal is applied to a known signal assigned to the other streams and a timing shift is also applied to an extensional known signal assigned to sub-streams,

degrees of priority are set beforehand to amounts of timing shift and, for the main streams, the amounts of timing shift are used, in order, from one having a higher degree of priority, and

for the sub-streams, the amounts of timing shift are used, in order, from one having a higher degree of priority.

8. A radio apparatus according to claim 6, wherein said adding unit is such that

using a known signal, as a reference, assigned to one of main streams, a cyclic timing shift within a known signal is applied to a known signal assigned to the other streams and a timing shift is also applied to an extensional known signal assigned to sub-streams, and

different values of amounts of timing shift are set to the plurality of streams, respectively.

9. A radio apparatus according to claim 7, wherein in said adding unit the known signal and the extensional known signal are formed by repeating a predetermined unit in time domain,

a combination of signs of the predetermined unit is defined so that an orthogonality holds among the streams, and

the combination of signs of the predetermined unit is so defined as to be fixed in the plurality of streams, respectively.

10. A radio apparatus according to claim 7, wherein in said adding unit the known signal and the extensional known signal are formed by repeating a predetermined unit in time domain,

while a combination of signs of the predetermined unit is defined so that an orthogonality holds among the streams, a degree of priority is given beforehand to the combination of signs of the predetermined unit, and

for the main streams, combinations of signs are used in order, from one having a higher degree of priority and, for the sub-stream, combinations of signs are used in order, from one having a higher degree of priority.

11. A radio apparatus according to claim 7, wherein said adding unit is such that the cyclic timing shift is applied to a data signal, and an amount of timing shift for the main stream is used as the amount of timing shift.

12. A radio apparatus according to claim 7, further comprising a modification unit which modifies at least a data signal, to which the known signal has been appended, among the packet signals to which the known signal has been appended, and outputs a modified signal to said transmitter,

said modification unit including:

a first processing unit which extends the number of main streams up to the number of a plurality of streams and then, for the extended stream, applies a cyclic timing shift within a known signal to a known signal assigned to the other streams using as a reference a known signal assigned to one of the extended streams; and

a second processing unit which extends the number of sub-streams up to the number of a plurality of streams and then, for the extended streams, applies a cyclic timing shift within an extensional known signal to an extensional known signal assigned to the other streams using as a reference an extensional known signal assigned to one of the extended streams,

wherein the amount of timing shift is set in a manner that the respective values of timing shift amounts used for the streams extended in the first processing unit are respectively equal to those for the streams extended in the second processing unit.

13. A radio apparatus according to claim 12, wherein an absolute value of the timing shift amount in said adding unit is so set as to be greater than that in said modification unit.