JP2003218765A - Radio communication equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve communication quality by improving the detecting precision of a receiving level in radio communication equipment provided with a first antenna and a second antenna wherein an antenna used for communication is switched between the first antenna and the second antenna on the basis of a receiving level of the first antenna and that of the second antenna in a level monitor slot in a communication frame. <P>SOLUTION: A receiving level detecting means detects the receiving level of the first antenna and that of the second antenna by using one level monitor slot. A communication antenna switching means switches the antenna used for communication between the first antenna and the second antenna on the basis of the receiving level of the first antenna and that of the second antenna which are detected by the receiving level detecting means. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a radio communication apparatus that performs radio communication by switching between a first antenna and a second antenna based on a reception level. The present invention relates to a wireless communication device capable of improving communication quality by improving reception level detection accuracy. [0002] For example, in a radio communication system using a PDC system (a system of Japanese digital cellular mobile communication),
Signals such as voice and data are wirelessly communicated between a mobile terminal device and a base station device. In addition, the portable terminal device includes, for example, an antenna (external antenna) provided outside the housing and an antenna (internal antenna) provided inside the housing, based on the reception level of each antenna. A device that performs antenna diversity for switching an antenna (communication antenna) used for communication is used. In recent years, a portable terminal device that has, for example, two antennas provided inside a housing and switches an antenna used for communication based on the reception level of each antenna has been implemented. FIG. 3 shows a configuration example of a slot provided in a communication frame used in wireless communication performed by such a portable terminal device. In the slot configuration shown in the figure, the mobile terminal device detects a transmission slot for transmitting a signal to a base station device or the like and the mobile terminal device detects a reception level of a signal from the base station device or the like by an antenna. And a reception slot for the portable terminal device to receive a signal from the base station device or the like are provided in one frame, and such a frame is repeated. Are located. Note that, for example, 1 ms is used as the time width of the LM slot. [0004] In a conventional portable terminal device, as a communication antenna switching during a call, the reception electric field levels of both antenna ends of a first antenna and a second antenna in one LM slot are determined by RSSI (Received Signal). Streng
th Indicator), and based on the measurement result, an antenna having a higher received electric field level is selected and switched. Thus, conventionally,
The switching of the antenna was performed every frame. Here, as the first antenna and the second antenna, for example, an external antenna and an internal antenna may be used, or an internal antenna and an external antenna may be used.
Also, for example, two internal antennas may be used. More specifically, FIG. 4 shows an example of the timing of a process of measuring a received electric field level according to a conventional example.
FIG. 3 shows an output signal (RSSI circuit output signal) from an RSSI circuit provided in a portable terminal device when an LM slot having a time width of 1 ms in an air interface arranged in the order of a transmission slot, an LM slot, and a reception slot. ), A measurement point (for example, a measurement point of an internal antenna) P1 for the first antenna and a measurement point for the second antenna as timing points (reception field level measurement points) for measuring the reception electric field level (For example, a measurement point of an external antenna) P2 is shown as an example. Note that RSS
The I circuit is a circuit that detects RSSI. [0006] However, in the method shown in the above-mentioned conventional example, for example, the response time of the output signal from the circuit for measuring the received electric field level (here, the RSSI circuit) is long. In such a case, erroneous detection of the reception electric field level may occur, and therefore, there is a problem that stable communication quality may not be maintained. Specifically, in the conventional method shown in FIG. 4, a predetermined time T1 from the start timing of the LM slot
Is measured at the point (first antenna measurement point) P1 at the time point when the elapsed time has elapsed,
A predetermined time T from the first antenna measurement point P1
The reception electric field level of the second antenna is measured at a point (second antenna measurement point) P2 at the point when 2 has elapsed. Note that a period T1 until the reception electric field level of the first antenna is measured and a period T2 until the reception electric field level of the second antenna are measured are, for example, 200 μs to
A period of 400 μs is used, for example, a period of the same length. [0008] Thus, in one LM slot, the first
In the method of measuring the reception electric field levels of both the first antenna and the second antenna, the period from when the output signal from the RSSI circuit starts to rise until the reception electric field level of the first antenna or the second antenna is measured. Time T1, T
2 is short, the received electric field level is measured when the output signal of the RSSI circuit does not completely rise, so that the erroneous detection of the received electric field level occurs, which causes erroneous selection of the antenna. In some cases, the communication by the mobile terminal device is interrupted. SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem. When wireless communication is performed by switching between a first antenna and a second antenna based on a reception level, the reception level of the antenna is reduced. It is an object of the present invention to provide a wireless communication device such as a portable terminal device capable of improving detection accuracy and thereby improving communication quality. [0010] In order to achieve the above object, a wireless communication apparatus according to the present invention comprises a first antenna and a second antenna. The antenna used for communication is switched between the first antenna and the second antenna based on the reception level of the first antenna and the reception level of the second antenna in the level monitor slot. That is, the reception level detection means detects the reception level of the first antenna and the reception level of the second antenna using one level monitor slot, respectively, and the communication antenna switching means detects the first and second reception levels by the reception level detection means. Antenna used for communication based on the reception level of the second antenna and the reception level of the second antenna.
And the second antenna. Therefore, when the reception level of the first antenna is 1
Since the reception level of the second antenna is detected using one level monitor slot and the reception level of the second antenna is detected using one level monitor slot, the output signal from the circuit for detecting the reception level of the antenna rises for each antenna. For example, the period between the start and the detection of the reception level of the antenna can be made longer as compared with the related art, so that the detection accuracy of the reception level of each antenna can be improved as compared with the related art, for example. And communication quality can be improved. That is, as a preferred embodiment, each antenna is configured to detect the reception level of the antenna when the output signal from the circuit for detecting the reception level of the antenna completely rises and becomes constant or almost constant. By doing so, it is possible to improve the detection accuracy of the reception level of each antenna. Here, for example, an external antenna or an internal antenna may be used as the first antenna,
Similarly, the second antenna may be, for example, an external antenna or an internal antenna. Thus, as a set of the first antenna and the second antenna, for example, a set of the external antenna and the internal antenna,
Various combinations such as a set of an internal antenna and an external antenna, a set of an internal antenna and an internal antenna, and a set of an external antenna and an external antenna may be used. The wireless communication device may be applied to various devices, for example, a portable terminal device such as a portable telephone terminal. Also, as an external antenna,
Various antennas may be used. Further, as the external antenna, for example, one antenna may be provided, or a plurality of antennas may be provided, and an antenna used for communication may be selected from the plurality of antennas. Various antennas may be used as the internal antenna.
Further, as the internal antenna, for example, one antenna may be provided, or a plurality of antennas may be provided, and an antenna used for communication may be selected from among them. As the communication frame, for example, a communication frame having the same configuration as that shown in FIG. 3 of the conventional example is used, but communication frames having other various configurations may be used. As the level monitor slot, for example, a slot having the same time width as the level monitor slot shown in FIG. 4 of the above-described conventional example is used. Is arranged so as to be included in the communication frame. For example, as described above, when the output signal from the circuit for detecting the reception level of the antenna for each antenna rises completely and becomes constant or almost constant, the reception level of the antenna can be detected. It is preferable to adopt a configuration. In such a configuration or the like, as the level monitor slot, a slot having other various time widths or arrangement in a communication frame may be used. Further, as the reception level of the first antenna and the reception level of the second antenna, various levels such as a reception electric field level by RSSI may be used. It is only necessary to use a level at which the user can determine whether the communication quality is better. Various modes may be used to switch the antenna used for communication based on the reception level. For example, the antenna (first antenna or second antenna) having the maximum reception level may be used. A mode of switching to use for communication, a mode of switching to use an antenna whose reception level exceeds a threshold value for communication, or the like can be used. Various modes may be used to detect the reception level of the first antenna and the reception level of the second antenna by using one level monitor slot. For example, other modes may be used. Detecting a reception level of one of the first antenna and the second antenna in one of the two level monitor slots adjacent to each other (eg, a transmission slot or a reception slot); A mode in which the reception level of the other antenna is detected in the other level monitor slot can be used. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A portable terminal device according to an embodiment of the present invention will be described with reference to the drawings. The mobile terminal device of the present example has a function of wirelessly communicating signals with a base station device or the like using a communication frame having a slot configuration similar to that shown in FIG. 3, for example. Further, as a component according to the present invention, the portable terminal device of the present example includes a first antenna and a second antenna for transmitting and receiving a radio signal, a signal reception level of the first antenna, and a second antenna. Each of the signal reception levels by the antenna is 1
A function of detecting (measuring) using two level monitor slots (LM slots) (a function of a reception level detecting means);
For example, an antenna (communication antenna) used for communication is detected by the first antenna and the second antenna based on the reception level of the first antenna and the reception level of the second antenna detected by the detection function. A function of switching to a higher reception level (a function of a communication antenna switching unit) is provided. In this example, for example, an internal antenna is used as the first antenna, and an external antenna is used as the second antenna, for example. Next, an operation example of the communication antenna switching processing performed by the portable terminal device of the present embodiment will be described. In this example, the switching of the communication antenna is performed every one LM slot in the portable terminal device shown in the above-mentioned conventional example. For example, the first antenna and the second antenna are changed every two consecutive LM slots. The measurement result of the antenna-end received electric field level of the second antenna is determined, and the communication antenna is switched to the one having better communication quality based on the determination result. Specifically, two consecutive LM slots (two consecutive frames) are used to detect both the reception electric field level of the first antenna and the reception electric field level of the second antenna. In the first LM slot of these two LM slots, the reception electric field level of the first antenna is measured, and in the second LM slot, the reception electric field level of the second antenna is measured. Then, after measuring the reception electric field level of the first antenna and the reception electric field level of the second antenna in this manner, the measurement results of these two antennas are compared, and the higher the measured reception electric field level is, An antenna (a first antenna or a second antenna) is selected and switched as a communication antenna. As a mode different from the present embodiment, for example, the reception electric field level of the second antenna is measured in the first LM slot, and the reception electric field level of the first antenna is measured in the second LM slot. It is also possible to use such an embodiment. Further, for example, when the reception electric field level measured for the first antenna is the same as the reception electric field level measured for the second antenna,
A mode for selecting any antenna may be used. FIG. 1 shows an example of the timing of the reception electric field level measurement processing according to this embodiment. The figure shows an LM having a time width of 1 ms in an air interface arranged in the order of a transmission slot, an LM slot, and a reception slot.
RSS provided in the portable terminal device regarding the slot time
An example of an output signal from the I circuit (RSSI circuit output signal) is shown, and an example of a timing point (receiving electric field level measuring point) P for measuring the receiving electric field level of the antenna is shown. Here, the reception electric field level measurement point P
Corresponds to a measurement point (first antenna measurement point) P1 for the first antenna at the time of the first LM slot, and a measurement point (first antenna measurement point) for the second antenna at the time of the second LM slot. (A second antenna measurement point) P2. Note that the RSSI circuit is a circuit that detects RSSI. Specifically, in the method of the present embodiment shown in FIG.
The reception electric field level of the first antenna is measured at a point (first antenna measurement point) P1 at a point when a predetermined time T = T1 has elapsed from the start timing of the first LM slot, and the second LM slot is measured. The reception electric field level of the second antenna is measured at a point (second antenna measurement point) P2 when a predetermined time T = T2 elapses from the start timing of the second antenna. As a result, as shown in the figure, the output signal from the circuit for detecting the reception electric field level of the antenna (in this example, the RSSI circuit) rises completely and becomes constant or almost constant. The reception electric field level can be detected. The period T1 until the reception electric field level of the first antenna is measured and the period T2 until the reception electric field level of the second antenna are measured are, for example, 50.
A period of 0 μs to 600 μs is used, and for example, a period of the same length is used. As described above, in the method of measuring the reception electric field level of the present embodiment, in one LM slot, only the reception electric field level of one antenna (first antenna or second antenna) is measured. The timing of the reception electric field level measurement point P with respect to the start of the rise (in this example, the start time of the LM slot) can be delayed as compared with, for example, the conventional case, that is, for each antenna, the reception electric field level of the antenna is measured. For example, the time T from when the output signal from the circuit that starts to rise to when the reception electric field level of the antenna is measured can be made longer than that of the related art. Next, referring to FIG. 2, an example of a procedure of a reception electric field level measurement process performed by the portable terminal device of the present embodiment will be described. That is, first, the reception electric field level of the first antenna is measured based on the signal received by the first antenna in the LM slot of the first frame (the first LM slot), and the measurement result is set as Q1. (Step S1). Next, in the reception slot of the first frame, reception is performed using, for example, the antenna (first antenna or second antenna) used in the previous reception slot (step S2). Next, the reception electric field level of the second antenna is measured based on the signal received by the second antenna in the LM slot of the second frame (the second LM slot), and the measurement result is set as Q2 ( Step S3). Here, the reception electric field level Q1 of the first antenna measured in the LM slot of the first frame,
The magnitude of the received electric field level Q2 of the second antenna measured in the LM slot of the second frame is compared (step S4). As a result of this comparison, for example, when it is determined that the reception electric field level Q1 of the first antenna is higher than the reception electric field level Q2 of the second antenna,
In the reception slot of the frame, the first antenna is switched as a communication antenna, and reception is performed by the first antenna (step S5). On the other hand, as a result of the comparison, for example, when it is determined that the reception electric field level Q2 of the second antenna is higher than the reception electric field level Q1 of the first antenna,
In the reception slot of the second frame, the second antenna is switched as a communication antenna, and reception is performed by the second antenna (step S6). Then, in the third frame, the process returns to the same process as the first frame again (step S1), and thereafter, the reception electric field level measurement process and the antenna switching process in the same manner as described above with two frames as one unit are repeated (step S1). S1 to step S6). As described above, in the portable terminal device of the present embodiment,
For example, provided in a PDC wireless communication system are a first antenna and a second antenna, an antenna-end received electric field level measuring circuit constituted by, for example, an RSSI detection circuit, and an antenna used for communication by an antenna diversity system. In a configuration having a function of switching between one antenna and a second antenna, the number of times of measuring the antenna-end received electric field level in one LM slot is set to one, and the first antenna or the second antenna is measured in one LM slot.
The reception electric field level of only one of the antennas is measured, thereby switching the communication antenna. Therefore, in the portable terminal device of this embodiment, even if the response time of the output of the RSSI circuit is long, for example, the reception electric field level measurement point P is delayed as compared with the conventional case, as described above. For example, as compared with the related art, it is possible to improve the measurement accuracy of the reception electric field level of the first antenna or the second antenna.
It is possible to reduce erroneous detection of the reception electric field level of each antenna and reduce erroneous selection of a communication antenna. Further, in the portable terminal device of the present embodiment, the response time of the RSSI circuit output is extended while maintaining the same level of accuracy of the measurement of the received electric field level as before, for example. It is possible to increase RSSI, for example, as compared with the prior art.
Since the fluctuation of the output signal from the circuit can be reduced, the signal detection accuracy can be improved. Specifically, for example, in order to obtain a stable RSSI, it is best to reduce the noise component by increasing the time constant of the RSSI circuit by adjusting the constant using an external capacitor or the like. On the other hand, in order to acquire RSSI in a short time, it is necessary to reduce the time constant, and the noise component relatively increases. For this reason, for example, in order to perform the reception electric field level measurement processing in a slot determined like the above-described LM slot, the time constant of the RSSI circuit is set by weighing these items having a trade-off relationship. Good to be. As a configuration example different from this embodiment, for example, a portable terminal device having a function of switching the number of times of detecting the reception level of the antenna in one LM slot can be implemented. As an example, for example, as shown in the conventional example, the number of times that the reception level of the antenna is detected in one LM slot is two times, and one L
A mode in which both the reception level of the first antenna and the reception level of the second antenna are detected in the M slot and the communication antenna is switched, and the reception level of the antenna in one LM slot as shown in this example, for example. A mode in which the reception level of the first antenna and the reception level of the second antenna are detected by using two LM slots and the communication antenna is switched with the number of times of detection being one according to the communication state or the like. It is also possible to implement a portable terminal device having a function of switching by switching. Here, the configuration of the wireless communication apparatus according to the present invention is not necessarily limited to the above-described configuration, and various configurations may be used. Further, the application field of the present invention is not necessarily limited to the above-described fields, and the present invention can be applied to various fields. The various processes performed by the wireless communication apparatus according to the present invention include, for example, a processor and a hardware
A configuration controlled by executing a control program stored in the OM may be used. For example, each functional unit for executing the processing may be configured as an independent hardware circuit. In addition, the present invention can be understood as a computer-readable recording medium such as a floppy (registered trademark) disk or a CD-ROM storing the above-mentioned control program, or the program (itself). By inputting it to a computer and executing it on a processor,
The processing according to the present invention can be performed. As described above, according to the radio communication apparatus of the present invention, the radio communication apparatus has the first antenna and the second antenna, and receives the first antenna in the level monitor slot in the communication frame. When switching the antenna used for communication between the first antenna and the second antenna based on the level and the reception level of the second antenna, the reception level of the first antenna and the reception level of the second antenna are each set to one. The antenna used for communication is switched between the first antenna and the second antenna based on the reception level of the first antenna and the reception level of the second antenna, which are detected using the level monitor slot. After the output signal from the circuit for detecting the reception level of each antenna starts rising, For example, the period until the reception level of the antenna is detected can be made longer than that in the related art, thereby improving the detection accuracy of the reception level of each antenna and eliminating erroneous selection of the antenna. Communication quality can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a timing chart of a reception electric field level measurement according to an embodiment of the present invention. FIG. 2 is a flowchart of a reception electric field level measurement according to an embodiment of the present invention. FIG. 3 is a diagram illustrating a configuration example of a slot in a communication frame. FIG. 4 is a timing chart of a reception electric field level measurement according to a conventional example. [Description of Signs] P: Antenna measurement point, P1: first antenna measurement point, P2: second antenna measurement point,

Claims (1)

1. A communication system comprising a first antenna and a second antenna, wherein communication is performed based on a reception level of the first antenna and a reception level of the second antenna in a level monitor slot in a communication frame. In a wireless communication apparatus that switches between the first antenna and the second antenna, the reception level for detecting the reception level of the first antenna and the reception level of the second antenna using one level monitor slot Detecting means, and communication antenna switching for switching an antenna used for communication between the first antenna and the second antenna based on the reception level of the first antenna and the reception level of the second antenna detected by the reception level detection means A wireless communication device comprising: