JP3799027B2 - Diversity receiver - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a diversity receiver that performs diversity reception using a plurality of antennas.
[0002]
[Prior art]
Here, a case will be described where, in a wireless communication system in which a plurality of terminal stations are accommodated in one base station, the base station is equipped with a plurality of antennas and performs diversity reception.
[0003]
FIG. 3 shows a configuration example of a conventional diversity receiving apparatus that performs diversity after detection.
In the figure, the receiving antenna is composed of a plurality (three in this case) of sector antennas 1, 2, and 3, and a signal transmitted from the terminal station is received by each antenna. The reception signals of the respective antennas are demodulated through the corresponding reception circuits 7-1 to 7-3, demodulation circuits 8-1 to 8-3, and baseband signal processing circuits 9-1 to 9-3. . The antenna determination circuit 12 detects the presence / absence of a code error corresponding to each antenna obtained by the baseband signal processing circuits 9-1 to 9-3, selects one antenna having no code error, and selects the baseband signal switch circuit 13 Selects and outputs a baseband signal corresponding to the antenna.
[0004]
[Problems to be solved by the invention]
By the way, in a system in which one base station manages a plurality of terminal stations in time and only signals from one terminal station are received by the base station in a certain time slot, the antenna having the best reception level and communication quality Diversity reception in which one is selected is possible. That is, reception by post-detection diversity shown in FIG. 3 is possible.
[0005]
However, in a random access type wireless communication system in which a plurality of terminal stations randomly access a certain time slot, the following problems occur when performing diversity reception in which one antenna is selected according to the reception level and communication quality. Arise.
[0006]
For example, when two terminal stations access simultaneously in a certain time slot, the reception level of the antenna that the signals from the two terminal stations collide with each other is combined, so the signals from one terminal station are combined. May be higher than an antenna receiving only the signal. At this time, the conventional post-detection diversity configuration shown in FIG. 3 can solve the problem of selecting an antenna whose reception level is increased due to signal collision. That is, even if the reception level increases due to a signal collision, the communication quality deteriorates due to the signal collision, so that antenna is not selected.
[0007]
However, when one antenna with good communication quality is selected in a certain time slot, even if the communication quality of a plurality of antennas satisfies the reference value in the next time slot, switching of antennas does not normally occur. That is, even if two terminal stations access at the same time and a signal is received by each antenna without causing a signal collision, the previously selected antenna is continuously selected. An imbalance in the access probability of the terminal station occurs. This becomes a problem when the sector antenna is used to deal with random access of a plurality of terminal stations as described above.
[0008]
An object of the present invention is to provide a diversity receiver capable of performing diversity reception in a random access wireless communication system without causing an imbalance of access probabilities of a plurality of terminal stations.
[0009]
[Means for Solving the Problems]
The diversity receiver of the present invention receives signals randomly accessed from a plurality of terminal stations by a plurality of antennas for each time slot, demodulates the received signals of each antenna, and selects a demodulated signal having a predetermined quality when, select no demodulated signal error-among the antennas corresponding demodulated signal, further selects and outputs the one of the demodulated signals if the same demodulated signal, the demodulated signal is not and the same one another without error Are multiplexed and output . As a result, among the demodulated signals corresponding to each antenna, it is possible to multiplex and output demodulated signals that are error-free and not identical to each other, that is, signals from a plurality of terminal stations.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of a diversity receiver of the present invention. Here, a configuration example is shown in which a sector antenna is used as an antenna, and post-detection diversity is performed using a code error after demodulation as a selection criterion.
[0012]
In the figure, signals transmitted from a plurality of terminal stations in the same time slot are respectively received by the sector antennas 1, 2, and 3. The reception signals of the respective antennas are demodulated through the corresponding reception circuits 7-1 to 7-3, demodulation circuits 8-1 to 8-3, and baseband signal processing circuits 9-1 to 9-3. Each demodulated signal is input to the coincidence detection / signal multiplexing circuit 10. At this time, the baseband signal processing circuits 9-1 to 9-3 detect the presence / absence of a code error corresponding to each antenna and notify the coincidence detection / signal multiplexing circuit 10. The coincidence detection / signal multiplexing circuit 10 selects and outputs one demodulated signal if there is the same demodulated signal among the demodulated signals with no code error. Further, if there is no error in the demodulated signals corresponding to each antenna and they are not identical to each other, the demodulated signals are multiplexed and output. The multiplexing method may be any method as long as it can be separated by a signal processing circuit at a later stage. Further, the demodulated signals may be output in parallel.
[0013]
FIG. 2 shows an operation example of the coincidence detection / signal multiplexing circuit 10.
The coincidence detection / signal multiplexing circuit 10 discards a demodulated signal in which a code error has occurred among demodulated signals corresponding to each antenna. Next, among the demodulated signals with no code error, the same demodulated signal is left and discarded. Here, assuming that the demodulated signal corresponding to the sector antenna 1 is D1, the demodulated signal corresponding to the sector antenna 2 is D2, and the demodulated signal corresponding to the sector antenna 3 is D3, D1 = D2 is determined for the demodulated signal D2, For the demodulated signal D3, D1 = D3 and D2 = D3 are determined, and the same demodulated signal is selected so as not to overlap.
[0014]
For example, when a signal from the terminal station A is normally received by the antenna sectors 1 and 2 in a certain time slot, since D1 = D2, the demodulated signal D1 corresponding to the antenna sector 1 is selected. This is similar to conventional post-detection diversity.
[0015]
In addition, when a signal from the terminal station A is normally received by the antenna sector 1 and a signal from the terminal station B is normally received by the antenna sector 2 in a certain time slot, D1 ≠ D2. Each demodulated signal D1, D2 is multiplexed and output. That is, signals from the terminal stations A and B can be received simultaneously. This can be said to be able to simultaneously receive signals from a plurality of terminal stations that are randomly accessed using a post-detection diversity apparatus configuration.
[0016]
Further, in a system in which a sector antenna is used as an antenna and signals from a plurality of terminal stations are separated and received by each sector antenna, the effect of simultaneously receiving signals from the plurality of terminal stations is great. Thereby, access from a plurality of terminal stations can be processed equally.
[0017]
【The invention's effect】
As described above, the diversity receiving apparatus of the present invention divides the demodulated signals that are error-free and not identical to each other among the demodulated signals corresponding to the antennas, and outputs the multiplexed diversity after detection and random access. Simultaneous reception of signals from the terminal station can be realized by the same device.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of a diversity receiver of the present invention.
FIG. 2 is a flowchart showing an operation example of the coincidence detection / signal multiplexing circuit 10;
FIG. 3 is a block diagram showing a configuration example of a conventional diversity receiving circuit (diversity after detection).
[Explanation of symbols]
1, 2, 3 Sector antenna 7 Reception circuit 8 Demodulation circuit 9 Baseband signal processing circuit 10 Match detection / signal multiplexing circuit 12 Antenna determination circuit 13 Baseband signal switch circuit

Claims (1)

In a diversity receiver that receives signals randomly accessed from a plurality of terminal stations by a plurality of antennas for each time slot, demodulates the received signals of each antenna, and selects a demodulated signal having a predetermined quality,
For each time slot, a means for detecting the presence or absence of an error in the demodulated signal corresponding to each antenna, a demodulated signal without an error among the demodulated signals corresponding to each antenna is selected, and if there is an identical demodulated signal, 1 Diversity receiving apparatus comprising: means for selecting and outputting two demodulated signals, and multiplexing and outputting demodulated signals that are error-free and not identical to each other .

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