JP3556464B2 - How to Prevent Call Disconnection of Multimode Radio - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing a call disconnection of a multimode radio, which can selectively receive signals of a plurality of different types of radio communication systems in the field of mobile communication.
[0002]
[Prior art]
At present, various types of wireless communication systems are in a mixed state.For example, even when focusing solely on domestic land mobile communications, there are many differences in the allocation of used frequency bands, including differences between analog and digital systems. There are types and types of wireless communication systems.
[0003]
In such a situation, recently, there has been an increasing demand for a multimode radio capable of selectively transmitting and receiving signals of a plurality of radio communication systems with one terminal. For example, multi-mode radios such as GSM (Global System for Mobile) and DCS-1800 (Digital Cellular System 1800), which are European cellular systems, are known. The background of the emergence of such multi-mode radios is not only the miniaturization and cost reduction of radios due to the advancement of LSI technology, but also communication using service areas individually covered by multiple radio communication systems. Increasing the possible area is an example.
[0004]
[Problems to be solved by the invention]
However, in such a multi-mode wireless device, if a user who roamed from one wireless communication system to another wireless communication system accidentally enters a dead zone, the position is located within a communicable service area of the wireless communication system before moving. Nevertheless, there was a problem that the call was interrupted. In addition, there is another problem that a call disconnection is likely to occur in a place where the reception intensity fluctuates with time due to fading or the like, in addition to the dead zone.
[0005]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and is directed to a multi-mode radio capable of reducing the probability of occurrence of a call disconnection when a user moves between service areas of different radio communication systems . The purpose is to provide a method for preventing call disconnection .
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a method for preventing a call disconnection of a multimode wireless device according to the present invention can receive signals of a first wireless communication system and a second wireless communication system, which are different types of wireless communication systems, respectively. In the method for preventing call disconnection of a multi-mode wireless device, during communication with the first wireless communication system, a result of measuring the strength of the received signal is used as a first measurement result, and the first measurement result is a predetermined measurement result. Determine whether or not the reference value or less, when it is determined that the reference value or less, after requesting a line connection to the second wireless communication system, receiving a signal from the second wireless communication system, The result of measuring the strength of the signal received from the second wireless communication system is defined as a second measurement result, and the first measurement result and the allowable communication quality in the first wireless communication system are guaranteed. The result of measuring the difference from the signal sensitivity is defined as the first difference, and the result of measuring the difference between the second measurement result and the reception sensitivity at which the allowable communication quality in the second wireless communication system is guaranteed is defined as the first difference. 2, the first difference and the second difference are compared, and as a result of the comparison, if the second difference is larger than the first difference, the second difference is transmitted from the first wireless communication system . A method for preventing a call disconnection of a multi-mode wireless device, characterized by performing control for switching to a call in a wireless communication system.
[0007]
As described above, the method for preventing a call disconnection of a multi-mode wireless device according to the present invention can be performed when the strength of the received signal of one wireless communication system falls below a predetermined reference value while receiving the signal of one wireless communication system. , diversity between the one of the wireless communication system and the other wireless communication system, i.e., by performing a process of receiving the signal only by selecting a radio communication system capable of ensuring a better line connection, different When a user moves between service areas of a wireless communication system, it is possible to prevent the occurrence of communication disconnection due to a dead zone or fading with a high probability.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0009]
FIG. 1 is a diagram illustrating a configuration of a receiving unit of the multimode wireless device according to the first embodiment of the present invention. The multi-mode wireless device supports communication with two wireless communication systems (hereinafter, simply referred to as systems S1 and S2), for example, a PHS (Personal Handy-phone System) and a PDC (Personal Digital Cellular). However, the type and number of wireless communication systems are not limited to this, and the type and number of systems to be combined can be freely changed.
[0010]
As shown in FIG. 1, the multi-mode radio includes an antenna 101, a filter 111, a signal strength measuring device 121, and a PHS detection circuit 131 as components corresponding to the reception system of the system (PHS) S1, As components corresponding to the reception system of the system (PDC) S2, there are an antenna 102, a filter 112, a signal strength measuring device 122, and a PDC detection circuit 132. Further, this multi-mode wireless device communicates between the system S1 / system S2 / each system S1 and S2 based on the signal reception intensity measured by the signal strength measuring devices 121 and 122 of the receiving system of each system S1 and S2. A control and switch circuit 141 for switching a reception mode to be enabled from among the three reception modes of diversity is provided.
[0011]
Next, the receiving operation of the multi-mode radio will be described with reference to the flowchart of FIG.
[0012]
The multi-mode wireless device of the present embodiment can communicate with two wireless communication systems S1 and S2 of PHS and PDC. In a normal reception mode, for example, only the PHS reception system corresponding to the system S1 is activated. Shall be.
[0013]
The signal transmitted from the base station of the system S1 is received by the antenna 101 (step 11), a signal of a desired channel is extracted from the received signal by the filter 111, and the signal is measured by the signal strength measuring device 121 and the PHS detection circuit 131, respectively. be introduced. The received signal is detected and demodulated by the PHS detection circuit 131, and is output as a signal subjected to reception processing by the multi-mode radio through the switch circuit 141.
[0014]
On the other hand, the signal strength measuring device 121 measures the strength of the received signal of the system S1 (step 12) and supplies the measurement result to the control and switch circuit 141. The control and switch circuit 141 determines that the received signal strength I1 is equal to or less than a predetermined reference value X1 such as when the user moves out of the service area of the system S1 or when the user enters a dead zone in the service area (step S1). 13) Call a line connection request to the base station of the system S2 (step 14), and if a line can be secured, a receiving system corresponding to the other system S2 in addition to the currently effective system S1 (for example, a PHS receiving system) (For example, a PDC receiving system) is enabled, and control is performed so as to perform diversity between the systems S1 and S2 (step 15).
[0015]
Diversity between the two systems S1 and S2 is determined by comparing the signal intensities I1 and I2 measured by the signal intensity measuring devices 121 and 122 of the respective receiving systems (steps 16 and 17), and determining which one has the higher signal intensity. This is performed by selecting a signal detected and demodulated by the detection circuit 131 or 132 of the system by the switch circuit 141 (steps 18 and 19).
[0016]
When the signal of the system S2 is selected, a signal corresponding to a desired channel is selected by the filter 112 from the signal received by the antenna 102, and is introduced into the signal strength measuring device 122 and the PDC detection circuit 132, respectively. . The received signal is demodulated by the PDC detection circuit 132, and the demodulated signal is output through the switch circuit 141. Even when only the receiving system corresponding to the system S2 is valid, the signal strength measuring device 122 measures the strength of the received signal, and the measurement result is introduced to the control and switch circuit 141. When the intensity I2 of the received signal of the system S2 becomes equal to or smaller than the reference value X2, the control and switch circuit 141 simultaneously enables the receiving system of the other system S1 in addition to the currently valid receiving system of the system S2. As a result, diversity reception is performed between the two systems S1 and S2 as described above.
[0017]
As described above, in the multi-mode wireless device of the present embodiment, the strength of the received signal of one of the wireless communication systems is monitored, and when the strength of the received signal falls below a predetermined reference value, the receiving system of the other wireless communication system is monitored. Is enabled together with the receiving system of the currently active system to perform diversity reception between the two systems. Thus, when the user moves between service areas of a plurality of wireless communication systems, for example, when the position in the service area of the destination system is in a dead zone, a signal is received by the reception system corresponding to the source system. Since the call can be received, a call disconnection does not occur.
[0018]
Note that the signal strength measuring devices 121 and 122 corresponding to the respective systems S1 and S2 may be arranged at the subsequent stage of the corresponding detection circuits 131 and 132, respectively.
[0019]
Also, as shown in FIG. 3, diversity reception between the two systems S1 and S2 includes minimum reception sensitivities A1 and A2 at which allowable communication quality is guaranteed in a reception system corresponding to each of the systems S1 and S2. The differences D1 and D2 from the measured received signal strengths I1 and I2 of the source system may be compared (step 27), and the demodulated signal of the system with the larger difference may be selected (step 28). , 29). The magnitude of the difference between the minimum receiving sensitivity and the received signal strength almost corresponds to the communication quality, and when the demodulated signal on the system side with the larger difference is selected, the judgment is made based only on the magnitude of the received strength. , Better communication quality can be obtained, and more effective diversity reception can be realized.
[0020]
For example, when the received signal strength of the PHS is −50 dBm and the received signal strength of the PDC is −55 dBm, the minimum receiving sensitivity of the PHS that can obtain the allowable communication quality is −97 dBm, and the minimum receiving sensitivity of the PDC is −116 dBm. Assuming that the difference D is 47 dB for PHS and 61 dB for PDC, the PDC is selected.
[0021]
Further, in the above-described embodiment, a case is described in which a signal of a system having a higher received signal strength is selected for the purpose of preventing a call disconnection during a diversity reception between two different systems S1 and S2. However, for the purpose of reducing the system usage fee borne by the user, the signal of the system with the lower usage fee may be selected.
[0022]
Further, from the viewpoint of service treatment for the subscriber, a system of a specific provider may be preferentially selected, and the system may be switched to another system only when the system cannot cope.
[0023]
Next, a multi-mode wireless device according to a second embodiment of the present invention will be described.
[0024]
FIG. 4 shows a configuration of a receiving unit of the multimode wireless device according to the second embodiment. As shown in the figure, this multi-mode wireless device includes a wideband antenna 201 that covers the frequency bands of a plurality of wireless communication systems, for example, PHS and PDC systems.
[0025]
At the time of diversity reception of each wireless communication system, signals of both systems are received by the wideband antenna 201. The signals of both systems received by the broadband antenna 201 are introduced into bandpass filters 211 and 212 having a pass bandwidth corresponding to the frequency band used by each system, and the signals of each system are output from the bandpass filters 211 and 212. Are separated and extracted.
[0026]
Subsequent operations are the same as in the first embodiment. That is, the signals that have passed through the bandpass filters 211 and 212 are respectively introduced into signal intensity measuring devices 221 and 222, where the signal intensity is measured, and the signals are introduced into the detection circuits 231 and 232 to be detected and demodulated. You. Each demodulated signal is output through a switch circuit 241 that is switched based on the received signal strength measurement results obtained by the signal strength measuring devices 221 and 222 corresponding to each system.
[0027]
The multimode wireless device of the present embodiment produces an effect that one broadband antenna can obtain the same effect as that of the first embodiment and can contribute to downsizing of the wireless device.
[0028]
Next, an example of a method of switching diversity reception in the above embodiment will be described.
[0029]
In FIG. 5, the wireless communication system before switching is S1, and the wireless communication system after switching is S2. C _{i, k} and U _{i, k} are the k-th reception channel slot of the i-th user in the systems S1 and S2, respectively. It is assumed that the signal strength of the received signal decreases on average during reception of the signal of the system S1, and a system switching request occurs at the timing of C1 _{, k} . In this case, since the timing of the C _{1, k} of the signal system S1 overlaps the receiving slot U _{1, m} of the m-th idle channel U ₁ connection schedule circuit system S2, use the guard time of the system S2 Then, the system is switched, and the communication of the system S2 is started from the slot U1 _{, m + 1} .
[0030]
In such a case, in the multimode wireless device of the present embodiment, the system is switched after the reception of the slots C1 _{, k + 1} of the system S1 immediately before U1 _{, m + 1} is completed, and the communication of the system S2 is started. . As a result, it is possible to smoothly perform system switching without generating switching noise generated at the time of diversity switching.
[0031]
In the multimode radio shown in FIG. 4, the portions after the bandpass filters 211 and 212 or the detection circuits 231 and 232 are not limited to those having a circuit configuration including a combination of passive elements and active elements, and may be, for example, a DSP (Digital). It may be configured by a radio having a form in which an equivalent function is incorporated as software in a digital signal processing circuit such as a signal processor. When such a software defined radio is used, there is an advantage that it can be applied to various wireless communication systems only by rewriting software in the DSP.
[0032]
【The invention's effect】
As described above, according to the present invention, while receiving a signal of one radio communication system, when the intensity of the received signal of the one of the wireless communication system is equal to or less than a predetermined reference value, of the one radio Diversity between the communication system and the other wireless communication system, that is, by selecting a wireless communication system that can ensure better line connection and performing processing of receiving only the signal, a service of a different wireless communication system When the user moves between the areas, it is possible to prevent the occurrence of communication interruption due to a dead zone or fading with a high probability.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a receiving unit of a multi-mode wireless device according to a first embodiment of the present invention; FIG. 2 is a flowchart showing a receiving operation of the multi-mode wireless device of FIG. 1; FIG. FIG. 4 is a flowchart showing another receiving operation of the multi-mode radio. FIG. 4 is a diagram showing a configuration of a receiving unit of the multi-mode radio according to the second embodiment of the present invention. FIG. 5 is a switching method in diversity reception of the present invention. [Explanation of symbols]
101, 102 Antennas 111, 112 Filters 121, 122 Signal Strength Measurement Device 131 PHS Detection Circuit 132 PDC Detection Circuit 141 Control and Switching Circuit

Claims (1)

In a method for preventing a call disconnection of a multi-mode wireless device capable of receiving signals of a first wireless communication system and a second wireless communication system, which are different types of wireless communication systems,
During communication with the first wireless communication system, a result of measuring the strength of the received signal is set as a first measurement result, and it is determined whether the first measurement result is equal to or less than a predetermined reference value,
When it is determined to be equal to or less than the reference value, after requesting a line connection to the second wireless communication system, receiving a signal from the second wireless communication system,
A result of measuring the strength of a signal received from the second wireless communication system is defined as a second measurement result, and the first measurement result and reception sensitivity at which an allowable communication quality in the first wireless communication system is guaranteed. And the result of measuring the difference between the second measurement result and the reception sensitivity at which the allowable communication quality in the second wireless communication system is guaranteed is defined as the second difference. Comparing the first difference with the second difference,
As a result of the comparison, when the second difference is larger than the first difference , control is performed to switch from the first wireless communication system to a call in the second wireless communication system. Mode radio call disconnection prevention method.

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