JPH0758682A - Mobile radio base station - Google Patents

Abstract

PURPOSE:To improve transmission reliability of down control burst to a mobile station by providing a means for transmitting the burst of the same contents for plural number of times changing antennas. CONSTITUTION:In a radio section frame, a transmission/reception frame length is defined as 5ms, eight slots are provided, first four slots T1-T4 are defined as transmission slots and second four slots R1-R4 are defined as reception slots. Then, for the down control burst, one transmission slot T1 is used for the respective frames. Thus, down control burst synchronization becomes 5Xnms which is the integral multiple of the transmission/reception frame length and for instance, information 1, the information 2, the information 3,... are respectively transmitted once by the antenna 1 and the antennas 1 and 2. That is, the antennas 1 and 2 are switched and transmission is performed respectively once for the respective pieces of the information. Thus, when a mobile station moving speed is sufficiently slower than a burst transmission cycle, the transmission reliability approximately the same as diversity reception can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile radio base station for improving the transmission reliability of downlink control bursts to mobile stations in a digital mobile communication system in which signals are transmitted from base stations to mobile stations by time division multiplexing. Regarding the station.

[0002]

2. Description of the Related Art In a conventional mobile communication system, a downlink burst from a base station to a mobile station is transmitted from one fixed antenna. In order to improve the transmission reliability of the downlink burst, the mobile station performs spatial diversity reception using multiple antennas.

[0003]

Conventionally, in order to improve the downlink burst transmission reliability, the mobile station needs to have a plurality of reception systems for performing reception diversity, which makes the mobile station compact and economical. Had been an obstacle. Alternatively, a base station that performs time division multiplex ping-pong transmission with a mobile station performs reception diversity with multiple antennas,
Transmit diversity was performed by transmitting with the antenna that could actually receive. However, when receiving an incoming call to the mobile station, there is a problem that the transmission diversity cannot be realized because the control burst is not transmitted from the mobile station in advance.

[0004]

According to the invention of claim 1, there is provided means for transmitting a burst of the same content a plurality of times by changing the antenna. According to the second aspect of the present invention, means for monitoring the response from the mobile station and means for changing the antenna and retransmitting when no response is detected by the monitoring are provided.

In each of the first and second aspects of the present invention, the plurality of antennas are sufficiently separated from each other so that space diversity can be obtained in mobile communication, for example, about 1/2 of the used wavelength.

[0006]

According to the invention of claim 1, even when the moving speed of the mobile station is very slow compared with the burst transmission cycle, or even when the mobile station is stopped, the mobile station receives with one antenna. Can also receive the transmit diversity effect of the base station. Therefore, the base station according to any one of the first and second aspects of the present invention enables highly reliable downlink burst signal transmission without using the mobile station as a diversity receiver, thus making the mobile station receiver compact and economical. You can do it.

[0007]

1 shows a burst transmission operation in a mobile radio base station when the invention of claim 1 is applied to a control channel of a second generation cordless telephone. In this embodiment, the case where two antennas are used is shown. The second-generation cordless telephone adopts a time division multiplex ping-pong transmission system in the wireless section, and the wireless section frame has a transmission / reception frame length of 5 ms as shown in FIG. 1A and is composed of eight slots. The two slots T1 to T4 are transmission slots, and the latter four slots R1 to R4 are reception slots. In the downlink control burst, one transmission slot T1 is used for every plural frames as shown in FIG. 1B. Therefore, the downlink control burst period is 5 × nms which is an integral multiple of the transmission / reception frame length. In this embodiment, as shown in FIGS. 1C and 1D, information 1, information 2, information 3, ...
Is transmitted once from each of antenna 1 and antennas 1 and 2. That is, the antennas 1 and 2 are switched for each piece of information, and the information is transmitted once. Therefore, the mobile station
It is possible to receive bursts from the antennas 1 or 2 having different propagation paths, and when the mobile station moving speed is sufficiently slower than the burst transmission cycle, transmission reliability similar to that of diversity reception can be obtained.

FIG. 2 shows a burst transmission operation in a mobile radio base station when the invention of claim 2 is applied to a control channel of a second generation cordless telephone. This embodiment also shows the case where two antennas are used. The radio section frame is shown in FIG. 2A and is the same as FIG. 1A, and the downlink control burst is alternately switched between transmission and reception every n frames as shown in FIG. 2B.

In this embodiment, the mobile radio base station transmits information 1, 2, 3, ... And receives and monitors a response corresponding thereto as shown in FIG. 2C. For example, as shown in FIG. 2C, when the response of the information 2 is non-reception, as shown in FIG.
As shown in FIG. 2E, the information 2 is retransmitted by switching to the antenna 2. Next, the downlink burst is transmitted by the antenna 2 until the response of the information 5 is not received, and the antenna 5 is switched from the antenna 2 to 1 and the information 5 is retransmitted when the response of the information 5 is not received.

The mobile radio base station can detect the propagation path condition between the antenna in use and the mobile station based on the response from the mobile station. When the propagation path condition deteriorates, the mobile radio base station changes the antenna. Since the burst is retransmitted by the mobile station, if the propagation condition deteriorates, the mobile station can re-receive a burst with a different propagation condition.If the mobile station moving speed is sufficiently slower than the burst transmission cycle, the same as diversity reception A certain degree of transmission reliability can be obtained.

In any of the inventions of claim 1 and 2, when the signal from the mobile station is received,
You may switch to the conventional transmission diversity. That is, you may make it transmit from the antenna received from the mobile station. The mobile radio base station device according to the invention of claim 1 can be applied to a system in which a base station such as a pager communicates with a mobile station in only one direction.

[0012]

As described above, according to the present invention, when the moving speed of the mobile station is sufficiently slower than the burst transmission cycle from the base station, the transmission is performed even if the signal is not received in advance from the mobile station. A diversity effect can be obtained, and signal transmission reliability can be improved.

[Brief description of drawings]

FIG. 1 is a time chart showing a burst transmission operation when the invention of claim 1 is applied to a second-generation cordless telephone.

FIG. 2 is a time chart showing a burst transmission operation when the invention of claim 2 is applied to a second-generation cordless telephone.

Claims (2)

[Claims] 1. A mobile radio base station in which a base station transmits a control signal to a mobile station by time division multiplexing, wherein a plurality of antennas and the same downlink burst transmitted from the base station to the mobile station are transmitted to the respective antennas. A mobile radio base station comprising: 2. A mobile radio base station communicating with a mobile station by time division multiple access, comprising: a plurality of antennas; and means for monitoring the presence or absence of a response corresponding to a downlink burst of a control signal transmitted to the mobile station, A mobile radio base station, characterized in that it has means for transmitting the downlink burst again by sequentially changing the antenna when the monitoring means detects that the uplink burst is not received.