JP5753731B2 - Mobile station equipment - Google Patents

Description

  The present invention relates to a mobile station apparatus capable of performing search processing for switching a frequency used for radio communication without interrupting voice communication.

A mobile station device such as a transceiver or a mobile phone performs wireless communication with a base station device at a frequency set for each base station device within a wireless communication area covered by the base station device.
For example, as illustrated in FIG. 5, a digital mobile communication system based on an SCPC (Single Channel Per Carrier) system compliant with ARIB STD-T61 includes a base station device and a mobile station device such as a portable wireless device or an in-vehicle wireless device. The base station apparatus is configured to perform wireless communication between the base station apparatus and the mobile station apparatus or between the mobile station apparatuses via the base station apparatus or directly. This communication method is based on the basis that one radio carrier corresponds to one communication frequency, and one base station apparatus provides a call service at one communication frequency.

In such a mobile communication system, a plurality of base station devices set with different communication frequencies are installed, and wireless communication areas of each base station device are adjacent to each other, thereby realizing wireless communication of the mobile station device in a wide area. ing.
Such wireless communication is performed by a communication frame including a traffic channel for transferring voice data and a plurality of control channels for transferring control data. For example, in the SCPC system, a communication frame having a configuration as shown in FIG. Used.
In FIG. 6, communication frames of 40 ms are continuous, and each communication frame includes LP + R, P, TCH, RI, SW, undefined, and TCH channels.

  LP + R is a channel of a linearizer preamble and a burst transient response guard time, and is assigned 20 bits. Here, the guard time is for guarding the signal content length only for the time when transmission signals from different mobile station apparatuses collide between the preceding and following received frames, and for the linearizer preamble and burst transient response. The guard time LP + R is used for improving the linearity of the transmission power amplifier in the mobile station apparatus and the base station apparatus.

P is a preamble channel and is assigned 2 bits. Here, the preamble is a special bit string for delimitation added to the beginning of data.
The TCH is a traffic channel and is assigned 96 bits and 160 bits. The voice data of the call is transferred by this traffic channel.

RI is a radio information channel and is assigned 56 bits. This RI is arranged on all physical radio channels and is used to transfer channel information such as a radio channel structure, an operation mode, and a communication mode.
SW is a synchronization word channel and is assigned 20 bits. The synchronization word is a bit string used for establishing synchronization between devices.
Undefined is assigned 20 bits.

  That is, from the viewpoint of a wireless communication system for transferring a call, a communication frame is composed of a traffic channel (TCH) for transferring voice data and other channels (LP + R, P, RI, SW). These other channels (LP + R, P, RI, SW) can be said to be control channels for transferring control data related to communication.

  Further, in the system in which a plurality of base station devices are arranged as described above to configure the wireless communication area of the mobile station device, as shown in FIG. When moving from the area of the base station apparatus 1 at f1 to the area of the base station apparatus 2 at the communication frequency f2, communication is performed to the frequency f2 of the base station apparatus 2 with higher reception quality (generally, reception field strength is higher). A handoff to switch the frequency is made. In this handoff, when the reception quality of the base station device receiving the radio wave deteriorates, the mobile station device measures the reception quality of other base station device surrounding base stations existing around the own station, The communication frequency is shifted to a peripheral base station with higher reception quality.

  In addition, as shown in FIG. 8, the reception quality with the own station 1 is deteriorated as in the case where the mobile station device 3 moves within the communication area of the own station 1 but has a poor radio wave condition. Nevertheless, if a neighboring base station with better reception quality is not found, the mobile station device 3 always attempts to continue the call with itself, but the mobile station device 3 always measures the reception quality of the neighboring base station. It continues.

  Patent Document 1 discloses a digital radio communication system in a mobile station apparatus that measures received field strengths of all base stations, assigns priorities, and switches from received field strengths higher than a threshold to a higher priority base station. Is described.

JP 2009-171445 A

Since there is a demand for miniaturization and price reduction, some mobile station apparatuses have only one reception system that performs radio reception. As a typical example, the mobile station apparatus is used in an SCPC system. In this case, handoff is performed by performing call communication with the base station apparatus (own station) and detecting the received electric field strength of other base stations (neighboring base stations) using one receiving system.
In order for the mobile station apparatus to measure the reception electric field of the neighboring base station while talking with the own station in this way, it is necessary to switch the frequency of the own station to the frequency of the neighboring base station. The method shown in a) and the method shown in (b) were employed to measure the received electric field strength by switching the frequency for handoff.

In the method shown in FIG. 9 (a), the mobile station apparatus abandons a call with the mobile station for a certain period of time in a state in which the mobile station apparatus is performing communication with the base station apparatus 1 (frequency f1: own station). Switch to the frequency (f2) of the base station 2 and measure the received electric field strength of the frequency.
In the method shown in FIG. 9 (b), the mobile station apparatus performs communication with the base station apparatus 1 (frequency f1: own station) while continuing communication with the own station to some extent, Thus, the frequency is switched to the frequency (f2) of the neighboring base station and the received electric field strength at the frequency is measured.

  However, when audio data is received and decoded for each frame (40 mm in the example in FIG. 6) and reproduced as audio, the time shown in FIG. In the method shown in FIG. 9A, there is a problem that the call is continued but the voice is interrupted. In any case, it is the mission of the wireless communication system. However, the quality of the call was degraded.

Even in a mobile station apparatus provided with a plurality of reception systems, even if it can be said that there is a difference in degree, it can be said that there is a similar problem.
That is, even when there are a plurality of reception systems, at least one of the reception systems is switched to a frequency of a neighboring base station without receiving a traffic channel, and it is impossible to predict when and when the call is transferred. Therefore, when the method shown in FIG. 9 is adopted, the quality of the call communication is generally reduced. It can be said.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a mobile station apparatus that realizes detection (measurement) of reception quality by frequency switching without degrading the quality of a call.

  In the present invention, for a plurality of continuous communication frames, the mobile station apparatus does not cause trouble even if it does not receive control data from all communication frames, or even if some trouble occurs, it is acceptable. It is an invention based on a novel idea that it is a thing that can be recovered, and it can be recovered, and the quality of call communication is reduced by using the time to receive this control data for detection of reception quality by frequency switching. In this way, detection of reception quality by frequency switching is realized.

  That is, the mobile station apparatus according to the present invention wirelessly communicates with the base station apparatus using a communication frame including a traffic channel for transferring voice data and a plurality of control channels for transferring control data used for communication. And a control means for switching the frequency of radio communication with the base station apparatus to another frequency and detecting the reception quality at the switched frequency during the time for receiving the control channel of the intermittent communication frame. It is characterized by that.

  Therefore, in the mobile station apparatus according to the present invention, although control data received from a plurality of continuous communication frames is intermittently lost, it is possible to receive necessary control data and perform communication control without any problem. At the same time, since voice data can be received from multiple consecutive communication frames without losing the voice data, it is possible to prevent occurrence of a situation in which the communication quality is deteriorated such as the time during which the call cannot be continued or the voice is interrupted. can do.

It should be noted that how much intermittent control channel non-reception is set depends on, for example, whether or not there is a problem due to loss of control data, and the degree of necessity to detect reception quality by switching the frequency. From the balance, it may be determined in accordance with the actual operation of the wireless communication system.
Further, even if the intermittency is not set at a predetermined interval in advance, when the reception quality falls below a predetermined value, the reception quality may be detected by switching the frequency at the time of receiving the control data. Even if this method is used, the control data from the communication frame at that time is lost when necessary. As a result, the reception quality is improved by switching to the frequency in the time to receive the control channel of the intermittent communication frame. It can be said that control to detect is performed.

  The mobile station apparatus according to the present invention wirelessly communicates with a base station apparatus using a communication frame including a traffic channel for transferring voice data and a plurality of control channels for transferring control data used for communication. When the reception quality of wireless communication with the base station apparatus is lower than a predetermined value, the frequency of wireless communication with the base station apparatus is set to other base station apparatuses in the time when the control channel is received. And a control means for detecting the reception quality at the switched frequency by switching to another frequency used for wireless communication.

Therefore, in the mobile station apparatus according to the present invention, in addition to the above, when the reception quality with the communicating base station apparatus (own station) falls below a predetermined value (a preset threshold value), Since the reception quality is detected by switching to the frequency of the base station (neighboring base station), it is only necessary to delete the control data as necessary.
This also only deletes the control data in the communication frame at the required timing. As a result, the reception quality is detected by switching the frequency in the time to receive the control channel of the intermittent communication frame. It can be said that control is performed.

Here, in the present invention, in addition to the intermittent communication frame, the time for switching the frequency and detecting the reception quality at the switched frequency is allocated to all control channels included in one communication frame. The time for receiving a plurality of adjacent control channels among a plurality of control channels included in one communication frame may be allocated.
For example, in the frame configuration shown in FIG. 6, control is performed to detect the reception quality by switching the frequency at the time of receiving RI, SW, and three undefined adjacent control channels, and the other control channels LP + R, P May be received.

  Thus, by assigning the time for receiving a part of the control channels among the plurality of control channels to the control for detecting the reception quality by switching the frequency, the control data to be lost can be minimized. Then, by assigning a plurality of adjacent control channels to the control of reception quality detection, a relatively long time continuous by these control channels can be used for the control, so that frequency switching and reception quality detection processing can be performed. Sufficient time can be secured.

In the present invention, how many of a plurality of control channels are allocated to control of reception quality detection by frequency switching, for example, the time required for processing of frequency switching and reception quality detection and the necessity of each control data However, in short, it is sufficient to secure the time that reception quality detection by frequency switching can be performed without hindrance.
In the present invention, when reception quality detection by frequency switching can be performed with one control channel, the reception quality at the switched frequency is detected for the time for receiving one control channel among a plurality of control channels. The mode assigned to the processing time is not excluded.

  Here, in the present invention, reception field strength is typically used for detection of reception quality, but various other parameters that can evaluate reception quality such as a reception bit error rate can be used. .

  According to the mobile station apparatus of the present invention, the reception quality is detected by frequency switching by intermittently using the time to receive the control channel. Can be realized. Therefore, handoff can be performed without degrading the call quality.

It is a figure which shows the structure of the mobile station apparatus which concerns on one Embodiment of this invention. It is a figure which shows a function structure to the principal part of the mobile station apparatus which concerns on one Embodiment of this invention. It is a figure explaining the process of the mobile station apparatus which concerns on one Embodiment of this invention. It is a figure which shows an example of the communication frame which can apply this invention. It is a figure which shows an example of a radio | wireless communications system. It is a figure which shows an example of the communication frame which can apply this invention. It is a figure explaining the handoff of a mobile station apparatus. It is a figure explaining the operation | movement of the base station switching of a mobile station apparatus. It is a figure explaining the conventional problem.

The present invention will be specifically described based on the embodiments shown in the drawings.
The mobile station apparatus according to the present embodiment is used in an SCPC digital mobile communication system, and wirelessly communicates with the base station apparatus using the communication frame shown in FIG.
That is, in each communication frame (40 ms) of continuous communication frames, a traffic channel (TCH) for transferring voice data and a plurality of control channels (LP + R, P, RI, SW, undefined) in the order shown in FIG.

FIG. 1 shows a schematic configuration of a part related to radio communication processing of the mobile station apparatus of the present embodiment. This mobile station apparatus includes one reception system and one transmission system, and the reception system includes A receiving device 10 and a transmitting device 11 forming a transmission system are connected to an antenna (antenna) 13 via an antenna duplexer 12.
The receiving device 10 and the transmitting device 11 are connected to the control device 14, and the control device 14 performs input / output processing of data to be transmitted / received and determination processing of the reception level (reception electric field strength) by frequency switching.

An auxiliary device 15 such as a transmitter / receiver is connected to the control device 14, and the voice input from the transmitter 15 is converted into digital voice data by the control device 14, and the transmitter 11 converts the voice data into a communication frame. Wirelessly transmitted from the antenna 13 by the traffic channel (TCH).
The voice data transmitted from the base station device through the traffic channel (TCH) of the communication frame is received by the receiving device 10 via the antenna 13, and the control device 14 performs analog conversion to output the voice from the receiving device 15.
In addition, the receiving device 10, the transmitting device 11, and the control device 14 perform transmission / reception processing such as synchronization holding by various control data received from the base station device through the control channel of the communication frame.

Here, in the present embodiment, as shown in FIG. 3, in one continuous communication frame (for example, one frame every several frames) in the continuous communication frame, three consecutive communication frames are consecutive. It is set so that the reception level detection determination processing is performed by switching the frequency at the time of receiving the control channel (RI, SW, undefined).
In this embodiment, the communication frequency is preset in each base station apparatus, and the frequency of each base station apparatus is preset in each mobile station apparatus. The reception level detection determination processing is performed by switching the frequency of the station to the frequency of the neighboring base station.

For example, when one 40 ms communication frame is set to perform the process of detecting the reception level by switching the frequency of one frame at an interval of 100 frames, the process of detecting the reception level by switching the frequency every second is performed. Is made.
Therefore, since the mobile station apparatus only loses 1% of the control data, there is no problem in the transmission / reception process, and the reception level detection / determination process in which the frequency is switched every second (that is, the search for neighboring base stations). Therefore, handoff is performed at an appropriate timing from the normal moving speed.
In other words, if the degree to which the handoff is appropriate and the degree to which the loss of control data is not hindered is set, the period (intermittentity) at which the reception level detection determination process is performed with the frequency switched. Good.

FIG. 2 shows a functional configuration provided for the mobile station apparatus of the present embodiment to perform reception level detection determination processing by frequency switching.
The receiving unit 20 and the level detecting unit 21 are configured by the receiving device 10.
The receiving unit 20 receives voice data and control data transmitted from the base station apparatus through the antenna 13 by the communication frame shown in FIGS. 6 and 3. In a normal state, this reception process is performed at the frequency of the base station apparatus (own station) that constitutes the radio communication area to which the mobile station apparatus belongs.
The level detection unit 21 sequentially detects the reception level of the reception process performed by the reception unit 20.

The control unit 22 includes the control device 10 and includes a level determination unit 23, a timing determination unit 24, and a frequency switching unit 25.
The level determination unit 23 determines the strength of the reception level detected by the level detection unit 21, and the timing determination unit 24 includes three consecutive control channels (RI, SW, undefined) of the communication frame received by the reception unit 20. ) Is received (reception start timing and reception end timing), and the frequency switching unit 25 instructs the receiving unit 20 to switch between the frequency of the local station and the frequency of the neighboring base station.

With reference to FIG. 3, the operation of each functional unit will be described.
First, the mobile station apparatus is in a state in which the receiving unit 20 receives audio data using a communication frame continuous from the base station apparatus 1 (own station) at the frequency f1.
In this state, the level detection unit 21 sequentially detects the reception level by the reception unit 20 and outputs the detected level to the level determination unit 23.

Then, for example, every other 50, when the timing for receiving a preset intermittent communication frame is reached, the timing determination unit 24 determines that the communication channel and the control channel included in the communication frame ( RI, SW, undefined) is received.
In synchronization with the timing of receiving the determined control channel (RI, SW, undefined), the frequency switching unit 25 sets the reception frequency to the other base station apparatus 2 at the timing of receiving the first control channel (RI). An instruction to change to the frequency f2 of the (neighboring base station) is output to the reception unit 20, and the reception frequency is the frequency of the original base station apparatus 1 (own station) at the timing of receiving the trailing control channel (undefined). An instruction to return to f1 is output to the receiving unit 20.

That is, during the time when three consecutive control channels (RI, SW, undefined) are received, the reception unit 20 is switched to the frequency f2 of the neighboring base station and performs reception processing. The reception level at this frequency f2 is the level detection unit. 21 detects and outputs to the level determination part 23.
Therefore, under the control of the control unit 22, the frequency f1 wirelessly communicating with the own station is switched to another frequency f2 (frequency of the surrounding base station) during the time to receive the control channel of the intermittent communication frame, Processing for detecting the reception level at the switched frequency f2 is performed.

Then, the level determination unit 23 compares the reception level at the frequency f1 of its own station with the reception level at the frequency f2 of the neighboring base station, and the frequency switching unit 25 has a strong reception level of the frequency f1 according to the comparison result. In this case, an instruction to return the reception frequency to the original frequency f1 is output to the reception unit 20, and when the reception level of the frequency f2 is strong, an instruction to change the reception frequency to the frequency f2 of this neighboring base station is given to the reception unit 20. Output.
Note that the reception frequency may be changed to the frequency f2 when the reception level of the frequency f2 is stronger than the reception level of the frequency f1 by a predetermined value. In the present invention, the reception level of the frequency f2 is predetermined. Various modes can be adopted such as changing the reception frequency to the frequency f2 when the reception level is higher than the reception level.

  Therefore, when the mobile station apparatus moves from its own station to the wireless communication area of the neighboring base station, a handoff is performed in which the reception frequency of the receiving unit 20 is switched to the frequency of the neighboring base station, and this handoff is performed. Therefore, even if the reception level is measured by switching the frequency, the voice data (TCH) can be received without overflowing, so that the processing for handoff can be performed without interrupting the voice communication. .

  Here, in the present embodiment, the time for detecting (measuring) the reception level by switching the frequency to another frequency is the time for receiving three consecutive control channels. This is to ensure the time required for the level detection unit 21 to detect the reception level. If the reception level can be detected in a short time, two consecutive control channels (for example, RI, SW) or any one of the control channels (for example, LP + R), the reception level may be detected (measured) by switching the frequency to another frequency.

  In the present embodiment, the transmission speed of the wireless communication system in which one frame is 40 ms is 9.6 Kbps. However, as shown in FIG. 3, the total number of bits of the three control channels is 56 + 20 + 20 = 96 bits. The frequency switching time is 10 ms. However, in practice, the time required to switch the frequency is also required, so that a high-performance synthesizer is used to shorten the frequency switching time, and the level detection unit 21 is required to detect (measure) the reception level. A time of about 5 ms is secured.

The present invention can also be implemented as a mode in which the control by the control unit 22 is slightly changed.
In the embodiment according to this aspect, the measurement of the reception level based on the frequency of the above-mentioned neighboring base stations is not performed in intermittent communication frames at predetermined intervals as in the above-described embodiment, but the reception level from the own station. Is performed when the value falls below a predetermined value.

  Therefore, the level determination unit 23 determines whether the reception level at the frequency (f1) of the local station detected by the level detection unit 21 is lower than a predetermined value. When the reception level is lower than the predetermined value, the timing determination unit 24 The timing for receiving the most recent communication frame (or some subsequent communication frame) and the control channel included in the communication frame is determined, and the time for receiving the determined control channel, as in the above embodiment, The frequency switching unit 25 changes the reception frequency of the reception unit 20 to the frequency (f2) of another base station device (neighboring base station), and handoff is performed according to the reception level of the frequency (f2) detected by the level detection unit 21. Let

  According to this embodiment, whether or not handoff is necessary can be performed at any time when the reception level decreases and becomes necessary, not the timing of receiving a communication frame (control channel) set intermittently in advance, Situations requiring handoff can be handled more quickly.

In the above-described embodiment, the control unit 22 configures the functional units 22 to 25 by executing the program according to the present invention using computer hardware such as a processor and a memory. These may be constituted by hardware circuits.
The present invention is typically applied to handoff to neighboring base stations, but is not limited thereto, and can be widely applied as a method for a mobile station apparatus to search for a radio communication frequency with good reception quality.

In addition, the present invention is not limited to the communication frame having the configuration shown in FIGS. 3 and 6, but a channel for transferring voice data (name is not limited to a traffic channel) and a channel for transferring control data (name is a control channel). Can be widely applied to mobile station apparatuses that wirelessly communicate with the base station apparatus.
For example, the present invention can also be applied to a mobile station apparatus that performs radio communication with a base station apparatus using an FDMA communication frame defined by ARIB STD-T61 as shown in FIG.

The FDMA communication frame shown in FIG. 4 has a channel (voice channel: TCH) for transferring voice data and a channel for transferring control data. And a channel (FACCH) for high-speed data transfer by stealing, a channel (SACCH) for temporarily low-speed data transfer by stealing TCH accompanying THC, and a housekeeping channel (RCH).
With regard to such a communication frame configuration, all, a part of continuous channels, or one of the channels for transferring control data can be allocated to the time when the reception quality is detected by switching the frequency as described above. That's fine.

1: base station device (own station), 2: base station device (neighboring base station),
3: mobile station device, 10: receiving device,
14: Control device, 20: Receiver
21: Level detection unit, 22: Control unit,
23: Level determination unit, 24: Timing determination unit,
25: Frequency switching unit,

Claims (2)

In a mobile station apparatus that wirelessly communicates with a base station apparatus by a communication frame including a traffic channel that transfers voice data and a plurality of control channels that transfer control data used for communication,
With the time to receive the control channel of the intermittent communication frame, the control unit detects the reception quality at the switched frequency by switching the frequency that is wirelessly communicating with the base station device to another frequency ,
The time for switching the frequency and detecting the reception quality at the switched frequency is a time for receiving a plurality of adjacent control channels among a plurality of control channels included in one communication frame. Station equipment. In a mobile station apparatus that wirelessly communicates with a base station apparatus by a communication frame including a traffic channel that transfers voice data and a plurality of control channels that transfer control data used for communication,
When the reception quality of wireless communication with the base station apparatus is lower than a predetermined value, the frequency of wireless communication with the base station apparatus is set to be wireless with other base station apparatuses in the time for receiving the control channel. A control means for detecting the reception quality at the switched frequency by switching to another frequency used for communication is provided .
The time for switching the frequency and detecting the reception quality at the switched frequency is a time for receiving a plurality of adjacent control channels among a plurality of control channels included in one communication frame. Station equipment.

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