Patent Application
20080008134
In accompanying drawings:
Referring to the accompanying drawings, embodiments of the present invention will be described.
In a transmission apparatus 10, an antenna number selection control portion 12 configured to select the number of control channel transmission antennas recognizes a current condition of a propagation channel based on transmission quality information transmitted from a quality information measurement portion 23 of a reception apparatus 20 so as to select the number of the transmission antennas for use in transmitting a control channel depending on the condition of the propagation channel. In addition, the antenna number selection control portion 12 informs a control channel generation portion 11 of the number of the selected transmission antennas.
The control channel generation portion 11 generates the control channel that includes multiplexed transmission control information obtained by multiplexing multiple pieces of transmission control information of radio signals for corresponding transmission antennas in control channel areas of radio signal transmission frames. Here, the number of the radio signal transmission frames corresponds to the number of the transmission antennas selected by the antenna number selection control portion 12. Then, a transmission portion 13 organizes transmission frames that include the control channel generated by the control channel generation portion 11 and a data channel for corresponding transmission antennas, and transmits the transmission frames through plural transmission antennas TA.
In the reception apparatus 20, a reception signal from the transmission portion 13 of the transmission apparatus 10 is received by a reception portion 21 through plural reception antennas RA. Then, a control channel demodulation portion 22 demodulates the control channel from the reception signal under control of a control channel reception antenna selection control portion 24 so as to obtain the information on the number of control channel transmission antennas. The control channel demodulation portion 22 sends the information to the control channel reception antenna selection control portion 24 which in turn determines based on the information on the number of the control channel transmission antennas whether the number of control channel transmission antennas has been changed.
By the way, when connections between the transmission apparatus 10 and the reception apparatus 20 are first made, the number of the control channel transmission antennas cannot be selected based on the transmission quality information. Therefore, the control channels are first transmitted by the multi-antenna control channel transmission method and then the transmission environment is observed based on the transmission quality information obtained by the quality information measurement portion 23 of the reception apparatus 20. Then, either the 1Tx control channel transmission method or the multi-antenna control channel transmission method is selected to transmit the control channel.
When the transmission methods are switched from 1Tx control channel transmission method to the multi-antenna control channel transmission method, or otherwise, control channel transmission selection bits stored as the transmission control information in the control channels are changed and notification of the change is sent to the reception apparatus 20. When the reception apparatus 20 recognizes the change in the number of the control channel transmission antennas, the reception apparatus 20 transmits an acknowledgment (ACK) of the proper reception of the change notification. After confirming that the change in the number of the control channel transmission antennas has been acknowledged, the transmission apparatus 10 changes the number of the control channel transmission antennas.
Although the change in the number of the control channel transmission antennas typically means a change from one antenna to the maximum number of antennas, the number may be changed from one to N (1<N< the maximum number) depending on the transmission environment, which is an embodiment according to the present invention. Obviously, in this case, the control channel transmission selection bits stored as the transmission control information in the control channels are required to be capable of representing any number from 1 to the maximum number.
In addition, when the number of the control channel transmission antennas is changed, the transmission apparatus 10 and the reception apparatus 20 may include identical antenna number selection tables for selecting the number of the control channel transmission antennas based on the transmission quality information, which makes it possible to quickly change the number of the control channel transmission antennas based on the transmission quality information in both the transmission apparatus 10 and the reception apparatus 20.
In this case, it is not necessary to store the control channel transmission selection bits in the control channel in order to inform the reception apparatus 20 of the bits. However, it is required to determine that the transmission quality information is properly transmitted from the reception apparatus 20 to the transmission apparatus 10. Namely, after the reception apparatus 20 receives from the transmission apparatus 10 the acknowledgment (ACK) indicating the successful reception of the transmission quality information from the reception apparatus 20, the number of the control channel transmission antennas is changed.
In addition, when an optimum number of the control channel transmission antennas is selected, an abrupt change in a propagation channel condition may prevent the control channel from being properly received. In order to address such a disadvantage, the reception apparatus 20 may be configured to count the number of reception errors of the reception signal (transmission control information) including the control channel. When the reception apparatus 20 detects that the number of reception errors reaches a predetermined number, the reception apparatus 20 places transmission channel abnormal bits in the storing area of the transmission quality information and informs the transmission apparatus 10 of the anomaly in the propagation channel, which allows the reception apparatus 20 and the transmission apparatus 10 to select the maximum number of the antennas so as to transmit/receive the control channel.
Also in the embodiment any number, between one and the maximum number, of the control channel transmission antennas can be selected since the number of the control channel transmission antennas cannot be selected based on the transmission quality information measured by the reception apparatus 20 when the connections between the transmission apparatus 10 and the reception apparatus 10 are first made. In this case, the control channel can be first transmitted using a predetermined number K of the antennas.
Referring to
When the reception apparatus 20 determines that the propagation channel condition is normal (YES at step 2-3), it is further determined whether an acknowledgment of an instruction of timing to change the number of the control channel transmission antennas is awaited (2-5). When the acknowledgment is determined to not be awaited, it is then determined based on the transmission quality information whether the number of the control channel transmission antennas should be changed (2-6). When it is determined that the number of the control channel transmission antennas is not to be changed (NO at step 2-6), the number is maintained the same (2-7). Then, the sequence is returned to step 2-3.
When the number of the control channel transmission antennas is determined to be changed (YES at step 2-6), the instruction of the timing to change the number of the control channel transmission antennas determined based on the transmission quality information is transmitted to the reception apparatus 20 (2-9). Then, the sequence is returned to step 2-3.
In addition, when it is determined at step 2-5 that the acknowledgment of the instruction of the timing to change the number of the control channel transmission antennas is awaited, it is then determined whether the acknowledgment of the instruction is properly received from the transmission apparatus 10 (2-8). When the acknowledgment is determined to not be properly received, step 2-9 is carried out as explained above. Then, the sequence is returned to step 2-3. On the other hand, when it is determined at step 2-8 that the acknowledgment is properly received, the number of the control channel transmission antennas is changed in accordance with the transmission quality information (2-10). Then, the sequence is returned to step 2-3.
Referring to
When the reception information of the control channel is not properly received (NG at step 3-3), it is further determined whether the number of the abnormal receptions reaches a predetermined value M (3-4). When the number of the improper receptions does not reach the predetermined value M (NO at step 3-4), the transmission quality information is generated (3-5); the reception apparatus 10 is informed that the Cyclic Redundancy Check (CRC) performed for the control channel of the reception signal results in failure (3-6); and the number of the control channel reception antennas is unchanged (3-11). Then, the sequence is returned to step 3-3.
When it is determined at step 3-4 that the number of the improper receptions reaches the predetermined value M, the reception apparatus 20 is informed of the transmission quality information which indicates that the propagation channel is in an abnormal condition (3-7). Then, after a prescribed number of frames are sent, the multi-antenna control channel transmission method using the maximum number of the control transmission antennas is employed, so that the control channel is received (3-9). Then, the sequence is returned to step 3-3.
When it is determined at step 3-3 that the reception information of the control channel is properly received (OK at step 3-3), it is further determined based on the received information whether the propagation channel is in an abnormal condition (3-8). When the transmission channel is determined to be in an abnormal condition, the multi-antenna control channel method is adopted so as to receive the control channel through the maximum number of the antennas (3-9). Then; the sequence is returned to step 3-3.
When it is determined at step 3-8 that the transmission channel is in a normal condition, it is further determined whether the instruction of the timing to change the number of the control channel transmission antennas is received from the transmission apparatus 10 (3-10). When such an instruction is not received, the number of the control channel reception antennas is kept the same (3-11). Then, the sequence is returned to step 3-3.
When it is determined at step 3-10 that the instruction of the timing to change the number of the control channel transmission antennas is received, an acknowledgment of the reception of the instruction is transmitted to the transmission apparatus 10 (3-12). After a period of time corresponding to the frames determined by the instruction for the change timing elapses, the control channel is received through the predetermined number of the reception antennas (3-13). Then, the sequence is returned to step 3-3.
A first additional embodiment of the present invention provides a communications system which includes a transmission apparatus that transmits a radio signal using plural transmission antennas and a reception apparatus that receives the radio signal using plural reception antennas. In the communications system, the multiple pieces of transmission control information of each radio signal transmitted from the corresponding antennas are multiplexed and the multiplexed transmission control information is stored in at least one of the control channel areas of the radio signal transmission frame for the transmission antennas. The communications system includes in the reception apparatus a transmission quality notification portion that obtains transmission quality information of the radio signal from the transmission apparatus and notifies the transmission apparatus of the transmission quality information. Moreover, the communications system includes in the transmission apparatus a transmission antenna number selection portion that selects the number of the transmission antennas for use in transmitting the multiplexed transmission control information based on the transmission quality information received from the transmission apparatus.
A second additional embodiment of the present invention provides the communications system according to the another embodiment, where both the transmission apparatus and the reception apparatus have antenna selection tables that store the number of antennas associated with the transmission quality information, where the both apparatuses refer to the antennas selection tables on the basis of the transmission quality information to recognize the number of the transmission antennas for use in transmitting the multiplexed transmission control information so as to select the number of the reception antennas and the transmission antennas for use in the multiplexed transmission control information.
A third additional embodiment of the present invention, the reception apparatus in the first or the second additional embodiments gives notice of an abnormal condition of the transmission paths as the transmission quality information to the reception apparatus in case the number of times when the multiplexed transmission control information is erroneously detected exceeds a predetermined number of times and the reception apparatus selects the maximum number of the transmission antennas for use in transmitting the multiplexed transmission control information when the reception apparatus receives the notice of the abnormal condition of the transmission paths from the transmission apparatus.
Additionally, a fourth additional embodiment of the present invention provides a transmission apparatus that stores in the control channel area of the transmission frame for at least one transmission antenna for a radio signal multiplexed transmission control information obtained by multiplexing the transmission control information of a radio signal to be transmitted through each transmission antenna and transmits the information. The transmission apparatus includes an antenna number selection portion that selects the number of transmission antennas based on the transmission quality information transmitted from a reception apparatus and a notification portion that notifies the reception apparatus of the number of selected transmission antennas.
A fifth additional embodiment according to the present invention provides a reception apparatus that receives a radio signal that stores in at least one control channel area of transmission frames for radio signals multiplexed transmission control information obtained by multiplexing all the transmission control information of radio signals received using multiple antennas. The reception apparatus includes a transmission quality notification portion that notifies a transmission apparatus of transmission quality information measured based on a reception signal, an antenna number selection table that stores the number of reception antennas in accordance with the transmission quality information, and a reception antenna number selection portion that refers to the antenna number selection table so as to select the number of reception antennas for use in receiving the multiplexed transmission control information stored in the control channel area of the radio signal.
The transmission antenna number selection portion of the first additional embodiment of the communications system may select one antenna or the maximum number of antennas.
The transmission antenna number selection portion of the first additional embodiment of the communications system may select any one of one though the maximum number of transmission antennas.
The transmission antenna number selection portion of the fourth additional embodiment of the transmission apparatus may select one antenna or the maximum number of antennas.
The transmission antenna number selection portion of the fourth additional embodiment of the transmission apparatus may select any one of one though the maximum number of transmission antennas.
The present application is based on Japanese Priority Application No. 2006-185235 filed on Jul. 5, 2006, with the Japanese Patent Office, the entire contents of which are hereby incorporated by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-185235 | Jul 2006 | JP | national |
