JP5225768B2 - Wireless communication terminal and wireless communication method - Google Patents

Description

  The present invention relates to a wireless communication terminal and a wireless communication method for performing wireless communication using a TDD (Time Division Duplex) method.

There is a TDD (Time Division Duplex) wireless communication system configured by wireless communication terminals and base stations.
A TDD wireless communication terminal synchronizes with the transmission / reception timing of a base station in order to correctly transmit / receive a TDD frame. As the distance between the wireless communication terminal and the base station increases, it is necessary to transmit at an earlier timing and to receive at a later timing. For example, in a TDD wireless communication terminal, a synchronization signal is exchanged with a base station, and based on TOA (Time of Arrival) information from the base station, a difference between the reception timing of the terminal and the reception timing of the actual synchronization signal, etc. The transmission / reception timing after the next frame is corrected. In this manner, the TDD wireless communication terminal synchronizes with the transmission / reception timing of the base station.

  Also, the TDD wireless communication terminal synchronizes with the frame number of the base station in order to correctly transmit and receive the TDD frame. This is because the frame number is used, for example, for encryption of a TDD frame, and therefore needs to be correctly synchronized between the wireless communication terminal side and the base station side. For example, a TDD wireless communication terminal exchanges a synchronization signal with a base station, and performs synchronization based on frame number information of the base station included therein.

In the TDD wireless communication system as described above, a synchronization signal transmitted from a wireless communication terminal may collide with a synchronization signal transmitted from another terminal. If the synchronization signals collide, the wireless communication terminal cannot naturally synchronize with the base station. Therefore, the lower the frequency of synchronization signal exchange with the base station in the wireless communication terminal (the longer the exchange period), the lower the possibility that the synchronization signals of a plurality of wireless communication terminals collide with each other. The overall performance of the system wireless communication system, the number of wireless communication terminals that can be accommodated, and the connection success rate are increased.
Therefore, the synchronization signal exchange period is set according to a trade-off between the hardware quality of the wireless communication terminal, the assumed moving speed of the terminal, the accuracy of transmission / reception timing, and the number of wireless communication terminals accommodated.

By the way, in order to improve the wireless communication performance, a wireless communication terminal having a plurality of CPUs and each CPU performing wireless communication control is required.
When such a wireless communication terminal is to be applied to a TDD wireless communication system as described above, a wireless control unit (DSP) that determines transmission / reception timing is generally provided for each CPU. . Therefore, it is necessary to synchronize with the base station for each CPU (need to exchange synchronization signals).

In a TDD wireless communication terminal having a plurality of CPUs, when the plurality of CPUs respectively exchange synchronization signals with the base station, for example, the following two methods are conceivable.
One is a method in which each CPU individually exchanges a synchronization signal with a base station. In this method, each of the plurality of CPUs performs synchronization signal exchange in the same manner as the wireless communication terminal of the single CPU described above. In this method, each CPU can obtain the same transmission / reception timing accuracy as the synchronization signal exchange of the above-described single CPU wireless communication terminal.
The other is a method in which a CPU for exchanging synchronization signals is fixed in advance to one of a plurality of CPUs. In this case, only one CPU of the plurality of CPUs exchanges the synchronization signal in the same manner as the above-described single CPU wireless communication terminal, and the other CPUs receive information on the synchronization result of the synchronization signal exchange performed. Based on this, the transmission / reception timing shift is corrected.

However, the two methods described above have the following problems.
In the first method, since the synchronization signal exchange with the base station is performed for each CPU, there is a problem that the synchronization exchange period is shortened according to the number of CPUs. As described above, the longer the synchronization exchange period, the higher the performance of the TDD wireless communication system, and the shorter the synchronization exchange period, the lower the overall system performance.
In the second method, a CPU that does not perform synchronization signal exchange acquires a synchronization result from the CPU that has performed the exchange, and corrects a transmission / reception timing shift using the synchronization result. For this reason, individual CPUs synchronize with the base station in nanosecond or microsecond order due to the time required to exchange the synchronization results between CPUs with each other or slight individual differences in communication performance of each CPU. It is difficult.
That is, a wireless communication terminal having a plurality of communication CPUs has a disadvantage that it is difficult to construct an efficient TDD wireless communication system.

  In order to eliminate the disadvantages described above, an object of the present invention is to provide a wireless communication terminal and a wireless communication method capable of performing efficient synchronization with a base station even when having a plurality of communication CPUs. .

In order to eliminate the disadvantages described above, the wireless communication terminal of the first invention includes a plurality of communication units that perform wireless communication with a base station using the TDD method, and a control unit, and the plurality of communication units are respectively It has a communication CPU having a timer function, and when one of the communication CPUs exchanges the synchronization signal with the base station, the other communication CPU exchanges the synchronization signal with the base station. The control unit monitors the wireless communication state of the plurality of communication units, and in accordance with the wireless communication state , the control unit communicates with the timer function of the communication CPU of the communication unit with the base station. The exchange cycle of the synchronization signal is set, and the synchronization signal is exchanged according to the exchange cycle.

  Suitably, the said control part can set the exchange period of the said synchronous signal to the timer function of the said CPU for communication at arbitrary timings.

  Preferably, when it is determined that the synchronization signal exchange with the base station of the plurality of communication units has failed, the control unit stops the timers of all the communication CPUs, and sets the timer function to the base function again. Reset the synchronization signal exchange cycle with the station.

According to a second aspect of the present invention, there is provided a wireless communication method for a wireless communication terminal having a plurality of communication units and a control unit for performing wireless communication with a base station using a TDD method, wherein each of the plurality of communication units has a timer function. When one of the communication CPUs performs a synchronization signal exchange process with the base station, the other communication CPU performs a synchronization signal exchange process with the base station. The control unit is configured to be different from the timing, and the control unit monitors the wireless communication state of the plurality of communication units, and according to the wireless communication state, the timer function of the communication CPU included in the communication unit, The step of setting the exchange cycle of the synchronization signal and the step of exchanging the synchronization signal in accordance with the set exchange cycle.

  ADVANTAGE OF THE INVENTION According to this invention, even when it has several CPU for communication, the radio | wireless communication terminal and radio | wireless communication method which can perform efficient synchronization with a base station can be provided.

Hereinafter, a wireless communication system including a wireless communication terminal according to an embodiment of the present invention will be described.
FIG. 1 is a diagram illustrating an example of a wireless communication system 100.
As shown in FIG. 1, the wireless communication system includes a communication terminal 1 and a base station 2.
For convenience of explanation, one communication terminal 1 and one base station 2 are shown in FIG. 1, but this is an example, and the wireless communication system 100 includes, for example, a plurality of communication terminals 1 and a plurality of communication terminals 1. The base station 2 may be included.
Note that the wireless communication system 100 in FIG. 1 is a TDD (Time Division Duplex) wireless communication system.

The communication terminal 1 is a wireless communication terminal device that performs wireless communication with the base station 2 using the TDD scheme.
The base station 2 is a device that performs wireless communication with the communication terminal 1 and is a terminal of the telephone network and relays calls and communication with the terminal to and from the telephone network.

Hereinafter, the communication terminal 1 of the embodiment of the wireless communication terminal of the present invention will be described in detail.
FIG. 2 is a block diagram illustrating an example of the configuration of the communication terminal 1.
As illustrated in FIG. 2, the communication terminal 1 includes two communication units 111 and 112, a display unit 12, an operation unit 13, an audio processing unit 14, and a control unit 15.
The communication unit 111 and the communication unit 112 have the same configuration.
As shown in FIG. 2, the communication unit 111 includes an antenna 201, an RF unit 202, a communication DSP (Digital Signal Processor) 203, and a communication CPU 204. Similarly, the communication unit 112 includes an antenna 211, an RF unit 212, a communication DSP 213, and a communication CPU 214. That is, the communication terminal 1 has two CPUs for communication.

The communication unit 111 and the communication unit 112 perform wireless communication processing by the TDD method in accordance with control of the control unit 15 described later. Specifically, for example, the communication CPU 204 of the communication unit 111 controls the RF unit 202 and the communication DSP 203 in accordance with the control of the control unit 15 to exchange synchronization signals with the base station 2 and transmit / receive timing. The wireless communication with the base station 2 is established through the antenna 201. Similarly, the communication CPU 214 of the communication unit 112 controls the RF unit 212 and the communication DSP 213 in accordance with the control of the control unit 15 to exchange synchronization signals with the base station 2 and correct transmission / reception timing deviations. The wireless communication with the base station 2 is established through the antenna 211.
Details of the wireless communication processing by the plurality of communication CPUs will be described later.

The display unit 12 is a display device such as an LCD (Liquid Crystal Display) or an organic EL (Electroluminescence) display, and displays a screen related to the operation according to various operations of the communication terminal 1. For example, information on the call destination is displayed when a voice call is made, and information on the call source is displayed when a call is received.
The operation unit 13 is an input device such as a numeric keypad or a cross key. The operation unit 13 receives user input during various operations of the communication terminal 1 and transmits an operation signal indicating the input content to the control unit 15.

The audio processing unit 14 converts an audio signal input from a microphone or the like not shown in FIG. 2 into audio data, or decodes audio data acquired from the base station 2 by the communication unit 111 or 112 into an audio signal. A process of outputting sound from a speaker or the like that does not perform is performed. With the processing of the voice processing unit 14, it is possible to make a voice call in the communication terminal 1.
The control unit 15 is a central processing unit that controls the communication terminal 1 in an integrated manner. That is, the various configurations of the communication terminal 1 described above are controlled during various operations of the communication terminal 1.

Next, an operation example in communication with the base station 2 in the communication terminal 1 will be described.
FIG. 3 is a flowchart for explaining an operation example when the communication terminal 1 communicates with the base station 2.
Step ST1:
The control unit 15 determines a period for exchanging the synchronization signal with the base station 2 for each of the communication CPUs 204 and 214 in the two communication units 111 and 112. Each of the communication CPUs 204 and 214 has a timer function, and the control unit 15 determines an exchange cycle in which the timer function of each communication CPU is determined in accordance with the synchronization signal exchange cycle determined for each communication CPU. Let them count to match. For example, when the control unit 15 sets the synchronization signal exchange cycle of the communication CPU 204 of the communication unit 111 to 20 seconds and the synchronization signal exchange cycle of the communication CPU 214 of the communication unit 112 to 60 seconds, the timer of the communication CPU 204 is set to 20 seconds. In addition, the timer of the communication CPU 214 is set to 60 seconds, and the count is disclosed. The synchronization signal exchange period (20 seconds, 60 seconds) described above is merely an example, and the present invention is not limited to this.

Step ST2:
The control unit 15 determines whether or not the timer (20 seconds) of the communication CPU 204 of the communication unit 111 set in step ST1 has expired. If it is determined that the timer has expired, that is, it is determined that the synchronization signal exchange period has been reached in the communication unit 111, the process proceeds to step ST3. Otherwise, step ST2 is repeated.
Step ST3:
The communication DSP 203 of the communication unit 111 generates a synchronization signal for performing synchronization with the base station 2.

Step ST4:
The RF unit 202 of the communication unit 111 transmits the synchronization signal generated in step ST3 to the base station 2.
Step ST5:
The RF unit 202 of the communication unit 111 receives the synchronization signal returned from the base station 2.

Step ST6:
The communication CPU 204 of the communication unit 111 performs synchronization processing with the base station 2 based on the synchronization signal returned from the base station 2 in step ST5. Specifically, based on the synchronization signal returned from the base station 2, the transmission / reception timing shift with the base station 2 is corrected and the frame number is synchronized.
Step ST7:
The control unit 15 determines whether or not the synchronization processing with the base station 2 by the communication CPU 204 in step ST6 is successful. If it is determined that the synchronization process has succeeded, the process proceeds to step ST8. If it is determined that the synchronization process has failed, all processes up to this step are abandoned, and the process returns to step ST1.

Step ST8:
When the synchronization process in step ST6 is completed, the control unit 15 resets the synchronization signal exchange period timer of the communication CPU 204 (in this embodiment, 20 seconds).
Step ST9:
The control unit 15 transfers the synchronization signal received from the base station 2 by the communication unit 111 in step ST5 to the communication CPU 214 of the communication unit 112.

Step ST10:
The communication CPU 214 of the communication unit 112 performs a synchronization process with the base station 2 based on the synchronization signal transferred from the communication unit 111 in step ST9. Specifically, based on the synchronization signal returned from the base station 2, the transmission / reception timing shift with the base station 2 is corrected and the frame number is synchronized.

Step ST11:
When the synchronization process in step ST10 ends, the control unit 15 extends the synchronization signal exchange cycle timer of the communication CPU 214. The initial value of the timer of the communication CPU 214 set in step ST1 is 60 seconds, and in step ST12, 20 seconds should have passed since then. This is because the timer of the CPU 204 has expired at step ST2 (the synchronization process at steps ST3 to 10 requires little time). That is, the remaining time of the timer of the communication CPU 214 is 40 seconds.
Here, the control unit 15 extends the timer of the communication CPU 214 for a predetermined time, for example, 10 seconds. That is, the remaining time of the timer of the communication CPU 214 is 50 seconds.
Then, after the timer of the communication CPU 214 is extended, the process returns to step ST2.

Now, after returning to step ST1, the operation example of the communication terminal 1 shown in FIG. 3 is repeated under the control of the control unit 15. However, every time steps ST2 to ST11 are repeated once, the remaining time of the timer of the communication CPU 214 in step ST11 is shortened by 10 seconds. Therefore, when steps ST2 to 11 are repeated six times, the CPU 214 in step ST11 The timer will expire (i.e., 120 seconds have elapsed since the start of processing). Hereinafter, an operation example of the communication terminal 1 when the timer of the communication CPU 214 of the communication unit 112 has expired will be described.
FIG. 4 is a flowchart for explaining an operation example of the communication terminal 1 when the timer of the communication CPU 214 of the communication unit 112 expires.

Step ST12:
The control unit 15 determines whether or not the timer of the communication CPU 214 of the communication unit 112 set in step ST1 has expired. As described above, in the present embodiment, the timer of the communication CPU 214 expires by repeating steps ST2 to ST11 shown in FIG. 3 six times.
If it is determined that the timer has expired, that is, it is determined that the synchronization signal exchange period in the communication unit 112 has been reached, the process proceeds to step ST13. Otherwise, the process returns to step ST2.
Step ST13:
The communication DSP 213 of the communication unit 112 generates a synchronization signal for performing synchronization with the base station 2.

Step ST14:
The RF unit 212 of the communication unit 112 transmits the synchronization signal generated in step ST13 to the base station 2.
Step ST15:
The RF unit 212 of the communication unit 112 receives the synchronization signal returned from the base station 2.

Step ST16:
The communication CPU 214 of the communication unit 112 performs the synchronization process with the base station 2 based on the synchronization signal returned from the base station 2 in step ST15. Specifically, based on the synchronization signal returned from the base station 2, the transmission / reception timing shift with the base station 2 is corrected and the frame number is synchronized.
Step ST17:
The control unit 15 determines whether or not the synchronization processing with the base station 2 by the communication CPU 214 in step ST16 is successful. If it is determined that the synchronization process has succeeded, the process proceeds to step ST18. If it is determined that the synchronization process has failed, all processes up to this step are abandoned, and the process returns to step ST1.

Step ST18:
When the synchronization process in step ST16 ends, the control unit 15 resets the synchronization signal exchange period timer of the communication CPU 214 (in this embodiment, 60 seconds).
Step ST19:
The control unit 15 transfers the synchronization signal received from the base station 2 by the communication unit 112 in step ST15 to the communication CPU 204 of the communication unit 111.

Step ST20:
The communication CPU 204 of the communication unit 111 performs synchronization processing with the base station 2 based on the synchronization signal transferred from the communication unit 112 in step ST19. Specifically, based on the synchronization signal returned from the base station 2, the transmission / reception timing shift with the base station 2 is corrected and the frame number is synchronized.

Step ST21:
When the synchronization process in step ST20 is completed, the control unit 15 extends the synchronization signal exchange cycle timer of the communication CPU 204 by 10 seconds and returns to step ST2.

As described above, according to the communication terminal 1 of the present embodiment, the communication CPU 204 and the CPU 214 of the two communication units 111 and 112 are set with timers having different synchronization signal exchange periods, respectively, When the timer of the communication CPU 204 with the shorter set timer expires, synchronization signal generation, transmission, and reception processing of the communication unit 111 are performed. Once the synchronization signal is exchanged between the communication unit 111 and the base station 2, the synchronization information obtained by exchanging the synchronization signal of the communication unit 111 is transferred to the other communication unit 112, and the synchronization process in the communication unit 112 is performed. Is performed by the synchronization information of the communication unit 111. When the processing up to this point is completed, the timer of the CPU 204 is reset and the timer of the CPU 214 is extended by a predetermined time. When such processing is repeated a predetermined number of times (the number of repetitions corresponds to a predetermined time obtained by extending the timer of the CPU 214), the timer of the CPU 214 of the communication unit 112 expires, and a synchronization signal is generated and transmitted by the communication unit 111. Reception processing is performed.
As described above, according to the communication terminal 1 of the present embodiment, the timing at which one of the plurality of communication CPUs performs the synchronization signal exchange process with the base station is always the same as that of the other communication CPUs with the base station. Since it is configured to be different from the timing for performing the synchronization signal exchange process, the exchange of the synchronization signals does not collide among a plurality of communication CPUs so that a suitable TDD wireless communication system can be constructed. Become.

  In the communication terminal 1 according to the present embodiment described above, the synchronization signal exchange period of the communication unit 111 is set to 20 seconds, and the synchronization signal exchange period of the communication unit 112 is set to 60 seconds. The present invention is not limited to this. These values can be dynamically changed according to the traffic amount and communication speed of the communication unit managed by each communication CPU. Moreover, since the communication terminal 1 as a whole operates in accordance with the timer for each communication CPU, it absorbs transmission / reception timing shifts caused by differences in clocks and communication performance for each communication unit or each communication CPU. Therefore, a more suitable wireless communication system 100 can be constructed.

In the operation example of the communication terminal 1 shown in FIGS. 3 and 4, the synchronization signal with the base station 2 is exchanged from the state where neither the communication unit 111 nor the communication unit 112 is communicating with the base station 2. However, since the communication unit and the base station 2 are always synchronized with each other by, for example, a traffic channel, the synchronization signal exchange as described above is performed. No processing is required.
Therefore, the control unit 15 of the communication terminal 1 can set the synchronization signal exchange period as described below, depending on whether the communication unit 111 and the communication unit 112 are communicating with the base station. .

(1) When neither the communication unit 111 nor the communication unit 112 is communicating with the base station 2 In this case, as shown in FIGS. 3 and 4, timers are respectively provided to the communication CPU 204 and the communication CPU 214. The synchronization signal exchange process with the base station 2 is executed at a synchronization signal exchange period corresponding to the timer.
(2) When only the communication unit 111 is communicating with the base station 2 and the communication unit 112 is not communicating with the base station 2 In this case, the communication CPU 204 of the communication unit 111 communicates with the base station 2 via the traffic channel. Therefore, the communication CPU 204 does not need the synchronization signal exchange process, but the communication CPU 214 of the communication unit 112 is not communicating, and therefore performs the synchronization signal exchange process at a predetermined cycle. Here, the predetermined period may be 20 seconds, for example.

(3) When only the communication unit 112 is communicating with the base station 2 and the communication unit 111 is not communicating with the base station 2 In this case, the communication CPU 214 of the communication unit 112 communicates with the base station 2 via the traffic channel. Therefore, the communication CPU 214 does not need the synchronization signal exchange process, but the communication CPU 204 of the communication unit 111 is not communicating, so the synchronization signal exchange process is performed at a predetermined cycle. Here, the predetermined period may be 20 seconds, for example.
(4) When the communication unit 111 and the communication unit 112 are both communicating with the base station 2 In this case, both the communication CPU 204 of the communication unit 111 and the communication CPU 214 of the communication unit 112 Thus, synchronization with the base station 2 is achieved, so that no synchronization signal exchange processing is required.
Thus, in the communication terminal 1 of the present embodiment, the synchronization signal exchange process can be performed dynamically or not according to the communication state of the plurality of communication CPUs with the base station. A more preferable wireless communication system 100 can be constructed.
Note that the control unit 15 may start the synchronization signal exchange process illustrated in FIG. 3 at an arbitrary timing regardless of whether the communication unit 111 and the communication unit 112 are communicating with the base station 2 or not. Thereby, communication with a more suitable communication system can be ensured.

The present invention is not limited to the embodiment described above.
That is, when implementing the present invention, various modifications and alternatives may be made to the components of the above-described embodiments within the technical scope of the present invention or an equivalent scope thereof.
In the embodiment described above, the number of communication units and communication CPUs is two, but the present invention is not limited to this. In the wireless communication terminal of the present invention, the number of communication units and CPUs may be any number as long as it is plural. The control unit may set the synchronization signal exchange cycle timer according to the communication state of each communication unit and the communication CPU, and each communication CPU may perform the synchronization signal exchange process according to the timer.
In the embodiment described above, the communication terminal 1 is assumed to be a mobile phone, but the present invention is not limited to this. For example, another communication device such as a PDA (Personal Digital Assistant) may be used.

FIG. 1 is a diagram illustrating an example of a wireless communication system. FIG. 2 is a block diagram illustrating an example of the configuration of the communication terminal. FIG. 3 is a flowchart for explaining an operation example during communication of the communication terminal with the base station. FIG. 4 is a flowchart for explaining an operation example of the communication terminal when the timer of the communication CPU of the communication unit expires.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Wireless communication system, 1 ... Communication terminal, 111 ... Communication part, 201 ... Antenna, 202 ... RF unit, 203 ... Communication DSP, 204 ... Communication CPU, 112 ... Communication part, 211 ... Antenna, 212 ... RF unit , 214 ... Communication CPU, 213 ... Communication DSP, 12 ... Display unit, 13 ... Operation unit, 14 ... Audio processing unit, 15 ... Control unit, 2 ... Base station

Claims (4)

A plurality of communication units that perform wireless communication with a base station in a TDD scheme;
A control unit;
Have
Each of the plurality of communication units includes a communication CPU having a timer function, and one of the communication CPUs performs a synchronization signal exchange process with the base station at the other communication CPU. Is configured to be different from the timing for performing the synchronization signal exchange process with the base station,
Wherein the control unit monitors the radio communication status of the plurality of communication units, in accordance with the radio communication state, the timer function of the communication CPU included in the said communication unit, of said synchronization signal with the base station wireless communication terminal for causing setting the replacement period, perform the exchange of the synchronous signal in accordance with the replacement period. Wherein, at an arbitrary timing, the wireless communication terminal according to claim 1, characterized in that it is possible to set the replacement cycle of the synchronizing signal to the timer function of the communication CPU. Wherein, when it is determined to have failed to exchange the sync signal with the base station of the plurality of communication unit, it stops the timer function of all of the communication CPU, again the timer function wireless communication terminal according to claim 1, characterized in that re-setting the replacement period of the synchronization signal of the base station. A wireless communication method for a wireless communication terminal having a plurality of communication units and a control unit for performing wireless communication with a base station in a TDD scheme,
When each of the plurality of communication units has a communication CPU having a timer function, the timing at which one of the communication CPUs performs a synchronization signal exchange process with the base station is the other communication The CPU is configured to be different from the timing for performing the exchange processing of the synchronization signal with the base station,
The control unit monitoring the wireless communication state of the plurality of communication units;
Depending on the wireless communication status, a step of the timer function of the communication CPU included in the said communication unit, to set the replacement cycle of the synchronizing signal with the base station,
A step of causing the exchange of the synchronization signal in response to said switching cycle and the setting,
A wireless communication method comprising:

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