JP4065176B2 - Mobile communication system, base station, mobile terminal, and mobile communication method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mobile communication system that performs uninterrupted hard handover.
[0002]
[Prior art]
W-CDMA has a function capable of simultaneously communicating by combining a plurality of calls such as a plurality of voice communication sets, a plurality of packet communication sets, and a voice communication and packet communication set in one mobile terminal. (For example, Patent Document 1). FIG. 8 is a diagram showing an example. The mobile terminal 1 performs voice communication with another mobile terminal through the base station 2, the base station 3, and the like, and simultaneously performs packet communication with the server 5 on the Internet.
[0003]
In W-CDMA, a technique called non-instantaneous hard handover (hereinafter abbreviated as HHO) that switches channels without interruption is standardized (for example, Patent Document 2).
In a mobile communication system using these two technologies, calls can be increased or decreased without interruption during communication. For example, a mobile terminal performs voice communication with another mobile terminal on a certain channel, It is possible to switch to a channel that combines the voice communication and the packet communication by performing HHO during the communication.
[0004]
[Patent Document 1]
JP 2001-309432 A
[0005]
[Patent Document 2]
JP 2001-231063 A
[0006]
[Problems to be solved by the invention]
However, in the case of channel switching for adding a call, there is a higher probability of call loss than channel switching for reducing calls. This is because in W-CDMA, when the chip rate is fixed, the symbol rate and the spreading factor are inversely proportional, so if a call is added, the symbol rate increases and the spreading factor decreases. This is because the lower the spreading factor, the higher the interference power, making it difficult to establish spreading code synchronization.
[0007]
When the call is lost, there is a problem that not only the communication of the call to be added cannot be started, but also the communication of the call connected so far is interrupted.
Therefore, an object of the present invention is to provide a mobile communication system and method that solves such a problem by an easy procedure.
[0008]
[Means for Solving the Problems]
In order to solve the above problem, a mobile communication system according to the present invention is a CDMA mobile communication system including a mobile terminal and a base station, and the first communication is performed between the mobile terminal and the base station. A communication means for performing communication related to the first call using a channel; an agreement means for deciding a switching time and a switchback time between the mobile terminal and the base station; and the communication when the switching time arrives Means for stopping communication using the first communication channel, and combining communication related to the first call and communication related to the second call on a second communication channel different from the first communication channel In order to start communication, synchronization establishment means that attempts to establish synchronization between the mobile terminal and the base station, and if synchronization cannot be established before the switch-back time arrives, the synchronization Establishment It stops the attempt to establish synchronization with the stage, and a resuming means for resuming the communication according to the first call using the first communication channel to the communication unit.
[0009]
Further, the communication means is provided in the mobile terminal, and is provided in the base station, terminal-side communication means for performing communication related to the first call using the first communication channel with the base station. And a base station side communication means for performing communication related to the first call using the first communication channel, and the arrangement means is provided in the mobile terminal, A request notifying means for receiving a request for channel switching and notifying the request to the base station, and the base station, and determining the switching time and the switching back time according to the request to the mobile terminal. A time notification means for notification, and an acquisition means provided in the mobile terminal for acquiring the notified switching time and switchback time, wherein the synchronization establishment means is provided in the base station. And when the switching time arrives, the mobile terminal is provided with a delivery means for delivering a synchronization signal for establishing synchronization with the second communication channel, and when the switching time arrives, the synchronization signal Is received, and when it is detected, the base station is notified that the synchronization has been established, and the restarting means is provided in the mobile terminal. When the synchronization timing cannot be detected before the switch-back time arrives, the detection means stops the detection of the synchronization timing, and the terminal-side communication means uses the first communication channel. A terminal-side resuming means for resuming communication related to the call, and a notification that the synchronization timing has been detected before the switch-back time comes, provided in the base station If not receiving may comprise a base station-side resuming means for resuming the communication according to the first call using the first communication channel to the base station-side communication means.
[0010]
Further, the agreement means further decides a re-switching time between the mobile terminal and the base station, and the restart means further uses the first communication channel by the communication means using the first communication channel. When communication related to a call cannot be resumed by the time when the re-switching time arrives, the synchronization establishment unit may be caused to try the synchronization establishment again.
[0011]
The mobile communication system of the present invention is a CDMA mobile communication system including a mobile terminal and a base station, and the base station uses a first communication channel with the mobile terminal. The first communication means for performing communication related to the first call and the communication related to the first call and the second call in parallel with the communication by the first communication means. Second communication means for performing communication in combination with communication related to the mobile station, wherein the mobile terminal performs communication related to the first call using the first communication channel with the base station. Third communication means to perform, storage means for preliminarily storing the switching time and switchback time, and when the switching time arrives, the third communication means stops communication using the first communication channel, and the second communication means The communication according to the first and the second over the communication channel In order to start communication in combination with communication related to a call, synchronization establishment means that tries to establish synchronization with the base station, and when synchronization cannot be established before the switch-back time arrives Comprises a resuming means for causing the synchronization establishing means to cancel the attempt to establish synchronization and for causing the third communication means to resume communication related to the first call using the first communication channel.
[0012]
Further, the synchronization establishment means further notifies the base station when the synchronization establishment is successful, and the first communication means further communicates when the notification is made by the synchronization establishment means. May be configured to stop.
The base station of the present invention is a base station used in a mobile communication system, and is a first communication means for performing communication related to a first call using a first communication channel with a mobile terminal. And, in parallel with the communication by the first communication means, a second communication means for performing communication combining the communication related to the first call and the communication related to the second call with the mobile terminal. Is provided.
[0013]
The mobile terminal of the present invention is a mobile terminal used in a mobile communication system, and performs communication related to the first call with the base station using the first communication channel. Communication means, storage means for preliminarily storing the switching time and switchback time, and when the switching time arrives, the communication means stops communication using the first communication channel, and the communication means uses the second communication channel on the second communication channel. In order to start communication combining the first and second calls, synchronization establishment means for trying to establish synchronization with the base station, and synchronization establishment could not be established before the switch-back time arrives In this case, the communication system includes: restarting means for causing the synchronization establishing means to cancel the attempt to establish synchronization and for causing the communication means to resume communication related to the first call using the first communication channel.
[0014]
The mobile communication method of the present invention is a CDMA mobile communication method performed between a mobile terminal and a base station, and uses a first communication channel between the mobile terminal and the base station. A communication step for performing communication related to the first call, an agreement step for deciding a switching time and a switchback time between the mobile terminal and the base station, and when the switching time arrives, the communication step Communication using one communication channel is stopped, and communication combining the communication related to the first call and the communication related to the second call is started on a second communication channel different from the first communication channel. Therefore, a synchronization establishment step that attempts to establish synchronization between the mobile terminal and the base station, and a synchronization establishment step when synchronization cannot be established before the switch-back time arrives. It stops the attempt to establish synchronization by, and a resumption step of resuming the communication according to the first call using the first communication channel.
[0015]
The mobile communication method of the present invention is a CDMA mobile communication method performed between a mobile terminal and a base station, wherein the base station establishes a first communication channel with the mobile terminal. A first communication step using the first communication to communicate with the mobile terminal in parallel with the communication by the first communication means and the second communication with the mobile terminal; A second communication step of performing communication in combination with communication related to the call, and the mobile terminal communicates with the first call using the first communication channel with the base station. A third communication step for performing the switching, and storing the switching time and the switching back time in the internal memory, and when the switching time arrives, the communication using the first communication channel by the third communication step is stopped, Said first on two communication channels In order to start communication that combines communication and communication related to the second call, a synchronization establishment step that attempts to establish synchronization with the base station, and synchronization establishment is performed before the switch-back time arrives. If not, the step of stopping the synchronization establishment by the synchronization establishment step is stopped, and the third communication step includes a resumption step of resuming the communication related to the first call using the first communication channel. .
[0016]
DETAILED DESCRIPTION OF THE INVENTION
<First Embodiment>
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIGS. 1A and 1B show a schematic configuration of a mobile communication system according to the present embodiment and a state of wireless transmission paths before and after HHO performed by the system.
[0017]
In the figure, the mobile communication system includes a mobile terminal 11 and a base station 12.
FIG. 2A shows the state of the transmission path between the mobile terminal 11 and the base station 12 before HHO is performed. Before the HHO, the mobile terminal 11 and the base station 12 perform voice communication using the transmission path 21. Audio data and control information are transmitted bidirectionally on the transmission path 21.
[0018]
FIG. 2B shows the state of the transmission path between the mobile terminal 11 and the base station 12 after HHO is performed. After the HHO, the mobile terminal 11 and the base station 12 perform voice communication using the transmission path 22, and simultaneously perform packet communication for a video distribution service or the like. Audio data and control information are bidirectionally transmitted to the transmission path 22, and in addition to this, video stream data and mobile units distributed from the video distribution server (not shown) to the mobile terminal 11 through the base station 12 Video stream data and the like transmitted from the terminal 11 to other terminals through the base station 12 are transmitted bidirectionally.
[0019]
Voice data transmitted from the base station 12 to the mobile terminal 11 is reproduced by the mobile terminal 11. Audio data transmitted from the base station 12 to the mobile terminal 11 is transferred from the mobile terminal 11 to a personal computer (PC in the figure) 13 and reproduced by the personal computer 13.
Communication in FIG. 1A is not limited to voice communication, and may be packet communication. The communication in FIG. 5B is not limited to a combination of voice communication and packet communication, and may be other combinations, for example, a combination of a plurality of voice communications or a combination of a plurality of packet communications. The contents of packet communication are not limited to the above, but may be a music distribution service, a videophone service, an Internet connection service, or the like.
[0020]
The mobile terminal 11 and the base station 12 switch the transmission path from the transmission path 21 to the transmission path 22 as shown in FIG. 2 by performing HHO. Conversely, the transmission path can be switched from the transmission path 22 to the transmission path 21 by HHO. This HHO is performed when the mobile terminal 11 or the base station 12 receives a request from the user of the mobile terminal 11, an instruction sent from the network side to the base station 12, or the like.
[0021]
For example, when the mobile terminal 11 receives an instruction to add packet communication from the user while the mobile terminal 11 and the base station 12 are performing voice communication using the transmission path 21, the mobile terminal 11 This is notified to the base station 12. Then, the mobile terminal 11 and the base station 12 try to connect via the transmission line 22 by cutting the transmission line 21. Attempting to connect means that the mobile terminal 11 and the base station 12 try to establish spread code synchronization in communication using the transmission path 22. Establishing spread code synchronization refers to an operation in which the time when the mobile terminal 11 performs despreading on the spread signal from the transmission side using the spread code matches the spread time of the spread signal. When spreading code synchronization is established, the mobile terminal 11 and the base station 12 start communication via the transmission path 22.
[0022]
However, the mobile terminal 11 and the base station 12 measure the time from the time of establishing the above, and if the synchronization cannot be established by communication over the transmission path 22 even after a predetermined time has elapsed, the operation is stopped. Then, synchronization is established with the communication via the transmission path 21 and voice communication using the transmission path 21 is resumed.
Next, functional configurations of the mobile terminal 11 and the base station 12 will be described.
[0023]
≪Mobile terminal configuration≫
FIG. 3 shows a functional block diagram of the mobile terminal 11.
As shown in the figure, the mobile terminal 11 includes an antenna 300, a reception system 301, a transmission system 303, a clock system 302, and a microprocessor 321.
≪Reception system configuration≫
The radio signal input to the antenna 300 is amplified by a low noise amplifier, A / D converted, and input to the reception system 301. Hereinafter, a signal input from the antenna 300 to the reception system 301 is referred to as a spread signal.
[0024]
First, a mechanism in which the reference timing is generated by the mobile terminal 11 will be described. Here, the reference timing is a timing used by the mobile terminal 11 to establish spreading code synchronization with the base station 12. This timing is generated based on the reference timing distribution ch signal transmitted by the base station 12.
The spread signal input from the antenna 300 to the reception system 301 is input to the reference timing distribution channel unit 307 and the despread code switching unit 305 of the despread unit 306. The reference timing distribution channel unit 307 performs despreading on the input spread signal using a specific spread code, and selectively demodulates the reference timing ch signal included in the spread signal. Then, the reference timing distribution channel unit 307 transmits the reference timing distribution channel signal to the in-device clock generator 315 of the clock system 302.
[0025]
The in-device clock generation unit 315 includes a PLL circuit, and synchronizes the reference signal from the clock source 316 with the reference timing distribution ch signal. Thereby, the in-device clock generation unit 315 generates a reference timing signal to be used by the mobile terminal 11 and sends the signal to each unit of the transmission / reception system.
Next, demodulation of audio data and moving image stream data will be described.
[0026]
In addition to 307, the despreading unit 306 has two despreading units corresponding to the channels used by the user for communication. These are the HHO unit 308 and the HHO unit 309.
The pre-HHO unit 308 stores a spread code for demodulating a spread signal received by communication using the transmission path 21 before performing HHO, and despreads the input spread signal using the spread code. Then, data including audio data and control information is extracted. The post-HHO unit 309 stores a spread code for demodulating a spread signal received by communication using the transmission path 22 after performing the HHO process, and the input spread signal is used as the spread code. Data including audio data, control information, and video stream data is extracted by despreading.
[0027]
The spreading code stored in each of the HHO pre-use unit 308 and the HHO post-use unit 309 is stored before each of the HHO pre-use unit 308 and the HHO post-use unit 309 performs spreading using these spreading codes. This is specified by the microprocessor 321 communicating with the base station 12 through the control channel.
[0028]
A despreading code switching unit 305 and a despreading code selection unit 310 are provided to selectively switch the HHO pre-unit 308 and the HHO post-unit 309 to operate. The despread code switching unit 305 inputs a spread signal to one of the pre-HHO unit 308 and the post-HHO unit 309 to perform processing. The despread code selection unit 310 selectively switches the output from the pre-HHO unit 308 and the post-HHO unit 309 and passes one output to the synchronization monitoring unit 304. The despread code switching unit 305 and the despread code selection unit 310 switch between the pre-HHO unit 308 and the post-HHO unit 309 in accordance with instructions from the microprocessor 321.
[0029]
The microprocessor 321 communicates with the base station 12 through the control channel to indicate information indicating when the despreading code switching unit 305 and the despreading code selecting unit 310 are switched (hereinafter referred to as HHO information). Is received from the base station 12. This HHO information will be described with reference to FIG. The microprocessor 321 instructs the despread code switching unit 305 and the despread code selection unit 310 to switch between the two units according to the HHO information and the reference timing generated by the in-device clock generation unit 315. Under the control of the microprocessor 321, the pre-HHO unit 308 operates before the HHO switching, and the post-HHO unit 309 operates after the HHO switching.
[0030]
The synchronization of the output of the despread code selection unit 310 is monitored by the synchronization monitoring unit 304. Then, the data is sent to the channel codec unit 318, error code correction is performed, and audio data, video stream data, and the like are extracted, and then sent to the host function 319. The host function 319 is a part having a telephone function or an interface part to the personal computer 13.
[0031]
≪Transmission system configuration≫
Next, the transmission system 303 will be described.
When user data such as audio data and moving image stream data to be transmitted from the mobile terminal 11 to the base station 12 is sent from the higher-order function 319 to the channel codec unit 318, the channel codec unit 318 wirelessly transmits the user data. Frames are assembled and sent to the spreading code switching unit 314 in the transmission system 303.
[0032]
The spreading code switching unit 314 and the spreading code selection unit 311 select the pre-HHO unit 312 and the post-HHO switching unit 313 in the same manner as the despreading code switching unit 305 and the despreading code selection unit 310 of the reception system 301. Are switched and operated. This switching is under the control of the microprocessor 321 as in the case of the reception system 301. By this control, the pre-HHO unit 312 operates before the HHO switching, and the post-HHO switching unit 313 operates after the HHO switching.
[0033]
The pre-HHO unit 312 stores a spreading code for spreading data including voice data and control information, which is transmitted by communication using the transmission path 21 before performing HHO, and stores the input data. It spreads with the spreading code and outputs the resulting spread signal.
The post-HHO switching unit 313 stores a spreading code for spreading data including audio data, control information, and video stream data that is transmitted by communication using the transmission path 22 after performing HHO. The input data is spread with the spreading code, and the resulting spread signal is output.
[0034]
The spreading codes stored in the HHO pre-unit 312 and the HHO post-unit 313 are stored before the HHO pre-unit 312 and the HHO post-unit 313 perform spreading using these spreading codes. This is specified by the microprocessor 321 communicating with the base station 12 through the control channel.
[0035]
The spread signal selected and output by the spread code selection unit 311 is output as a radio signal from the antenna 300 through analog modulation.
≪Configuration of clock system≫
Next, the clock system 302 will be described.
The clock system 302 includes an in-device clock generator 315, a clock source 316, and a monitoring timer 317.
[0036]
As described above, the in-device clock generation unit 315 extracts the timing from the reference timing ch signal transmitted from the base station 12, and synchronizes the reference signal generated by the clock source 316 with this timing, thereby moving the mobile terminal. 11 is sent to the microprocessor 321 and each part of the transmission / reception system.
[0037]
The in-device clock generation unit 315 receives a report from the synchronization monitoring unit 304 as to whether the current synchronization is established or not. When receiving the report of out of synchronization, the in-device clock generation unit 315 confirms whether the clock of the clock source 316 is synchronized with the reference timing.
≪Base station configuration≫
Next, the base station 12 will be described.
[0038]
FIG. 4 is a block diagram showing the configuration of the base station 12.
The base station 12 in the figure is basically the same as the mobile terminal 11. The difference is that the base station 12 does not include the reference timing distribution channel unit in the despreading unit 406, but includes the reference timing distribution channel unit 407 in the diffusion unit 420 instead.
[0039]
This is because the reference timing distribution ch is one-way communication from the base station 12 to the mobile terminal 11. That is, the base station 12 divides the clock generated by the clock source 416 into an appropriate frequency by the in-device clock generation unit 415, and uses this as a reference timing for each part in the base station 12, and at the reference timing. Based on this, a reference timing distribution channel signal is generated, spread by the reference timing distribution channel 407, and distributed to the mobile terminal 11 through the spread code selection unit 411 and the antenna 400.
[0040]
Unit switching by the despreading code switching unit 405, despreading code selection unit 410, spreading code selection unit 411, and spreading code switching unit 414 is controlled by the microprocessor 421 similarly to the mobile terminal 11, and the mobile terminal 11 Done in sync with
≪Process flow≫
Next, the flow of processing will be described with reference to FIGS.
[0041]
FIGS. 5A and 5B are diagrams for explaining operations performed by both the base station 12 and the mobile terminal 11. 5 (a) and 5 (b) show the operation in the past time zone in FIG. 5 (a) than in FIG. 5 (b).
(A), (b), J-6, J-5, ..., J, J + 1, ..., K-1, K, ..., L-1, L, ..., Each rectangle to which M-1, M,... Are added indicates a frame sequence.
[0042]
In FIG. 9A, HHO is performed at the beginning of the frame J. Until just before the HHO timing, the base station 12 and the mobile terminal communicate via the functional channel L (transmission path 21), switch to the functional channel H (transmission path 22) immediately after the HHO timing, and spread in the functional channel H. Try to establish code synchronization. The HHO timing 201 is a time determined between the base station 12 and the mobile terminal 11 based on the HHO information sent from the base station 12 and the reference timing.
[0043]
After switching at the HHO timing 201, the synchronization monitoring units 304 and 404 of the base station 12 and the mobile terminal 11 monitor whether or not spread code synchronization is established in the functional channel H.
In the previous HHO information, an upper limit of a period from the HHO timing 201 to the successful establishment of spreading code synchronization is defined, and this period is called a protection period. The monitoring timers 317 and 417 detect the elapse of the protection period 202, and if the synchronization is not successfully established at the time of detection, the base station 12 and the mobile terminal 11 switch the channel to the functional channel L before HHO. Return, attempt to establish synchronization on the function channel L.
[0044]
Furthermore, if synchronization cannot be established on the channel from the time of switching to the functional channel L until the protection period elapses, the base station 12 and the mobile terminal 11 switch the channel to the functional channel H after HHO again. Try to establish synchronization.
The base station 12 and the mobile terminal 11 repeatedly switch and switch back between the two channels unless synchronization is established.
[0045]
In addition, an upper limit of a period until the establishment of synchronization in any channel is successfully established by this repetition is referred to as a monitoring period. The monitoring timers 317 and 417 detect the progress of this monitoring period. If the synchronization is not established in any channel when the monitoring has elapsed, the communication is disconnected here.
[0046]
The protection period and the monitoring time are not fixed values and can be changed as appropriate. In this embodiment, for example, the protection period is 500 ms and the monitoring period is 2 seconds. However, these may not be the same value every time, and may be made longer or shorter every time.
As described above, when synchronization cannot be established in the functional channel immediately after the HHO timing, the base station 12 and the mobile terminal 11 establish synchronization by switching to the functional channel before the HHO timing. Even when switching to a channel that is difficult to establish synchronization due to a low spreading factor, such as when switching to higher-speed communication and trying to perform communication, even after switching If synchronization cannot be established within a predetermined period, communication disconnection is effectively avoided by switching to a low-speed communication channel that is relatively easy to establish synchronization and establishing synchronization. During this time, the spread codes of the two channels are not used for other communications.
[0047]
FIG. 6 shows state transitions between the base station 12 and the mobile terminal 11.
When the HHO is activated in the communication state 501 between the base station 12 and the mobile terminal 11, the base station 12 and the mobile terminal 11 transition to a synchronization establishment wait state 502 that attempts to establish synchronization on the functional channel ch after HHO, triggered by the HHO timing.
Both of them measure the protection period immediately after transitioning to this state 502, and when the protection period times out, they start an attempt to establish synchronization on the functional channel ch before HHO, and transition to the synchronization establishment wait state 503.
[0048]
As in the state 502, both measure the protection period immediately after the transition to the state 503, and start an attempt to establish synchronization on the functional channel ch after HHO, triggered by the timeout of the protection period. Transition to the wait state 502.
In this way, when the state 502 and the state 503 are reciprocated and synchronization is established before the protection period elapses in either state, the state transits to the communication state 501 as a trigger.
[0049]
Alternatively, the base station 12 and the mobile terminal 11 measure the monitoring period immediately after the transition from the communication state 501 to the state 502, and when the monitoring period elapses in the state 502 or the state 503, the time 502 or Transition from the state 503 to the disconnected state 504 stops the attempt to establish synchronization.
Second Embodiment
Hereinafter, the second embodiment of the present invention will be described with a focus on the differences from the first embodiment.
[0050]
FIG. 7 is a diagram for explaining the present embodiment.
In the figure, a transmission path 61 corresponds to the transmission path 21 in FIG. 2 and a transmission path 62 corresponds to the transmission path 22.
The base station 12 performs transmission through the transmission path 61 and the transmission path 62 simultaneously. That is, the base station 12 transmits voice data and control information for voice communication to the mobile terminal 11 using the transmission path 61, and at the same time, voice data and control for voice communication and packet communication using the transmission path 62. Information and video stream data are transmitted.
[0051]
The mobile terminal 11 performs voice communication with the base station 12 using the transmission path 61 before HHO, and performs voice communication and packet communication with the base station 12 using the transmission path 62 after HHO.
As described above, in the second embodiment, the base station 12 transmits various data using both the transmission path 61 and the transmission path 62 at the same time, whereas the mobile terminal 11 uses the transmission path 61 before the HHO. The transmission path 62 is used after the use HHO.
[0052]
When the mobile terminal 11 receives an HHO instruction during communication on the transmission path 61, the mobile terminal 11 starts a synchronization acquisition process on the transmission path 62. The mobile terminal starts measuring time by an internal timer from the start. The mobile terminal 11 notifies the base station 12 to disconnect the transmission path 61 when synchronization can be established on the transmission path 62 before the preliminarily stored protection period elapses. If synchronization cannot be established on the transmission line 62 even after the protection period has elapsed, the synchronization acquisition process on the transmission line 62 is stopped, the synchronization acquisition is performed on the transmission line 61, and the communication returns to the communication on the transmission line 61. .
[0053]
If synchronization cannot be established even after a predetermined period has elapsed since the start of synchronization acquisition on the transmission path 61, the mobile terminal 11 starts the synchronization acquisition process on the transmission path 62 again.
[0054]
【The invention's effect】
A mobile communication system according to the present invention is a CDMA mobile communication system including a mobile terminal and a base station, and uses a first communication channel between the mobile terminal and the base station. A communication means for performing communication related to the call, an agreement means for deciding a switching time and a switchback time between the mobile terminal and the base station, and when the switching time arrives, the communication means is connected to the first communication channel. In order to stop communication using and start communication combining the communication related to the first call and the communication related to the second call on a second communication channel different from the first communication channel, Synchronization establishment means for trying to establish synchronization between the mobile terminal and the base station, and if synchronization cannot be established before the switch-back time arrives, the synchronization establishment means attempts to establish synchronization In It is allowed, and a resuming means for resuming the communication according to the first communication channel to the first call using the communication means. This is realized by the base station and the mobile terminal having determined the switch-back time before attempting to establish synchronization.
[0055]
The agreement means may decide a predetermined period (protection period) instead of the switchback time. The predetermined period corresponds to a period between the switching time and the switching back time. In this case, the synchronization establishing unit and the resuming unit perform the respective processes when a predetermined time has elapsed from the switching time instead of the switchback time. The detection that the predetermined time has elapsed from the switching time is performed by the base station and the mobile station having an internal timer and measuring the elapsed time from the switching time.
[0056]
According to this configuration, the mobile terminal and the base station resume communication in the first communication channel when spreading code synchronization in the second communication channel cannot be established even when the switchback time arrives. Even if the addition of the second call fails, the communication related to the first call can be continued.
Further, the communication means is provided in the mobile terminal, and is provided in the base station, terminal-side communication means for performing communication related to the first call using the first communication channel with the base station. And a base station side communication means for performing communication related to the first call using the first communication channel, and the arrangement means is provided in the mobile terminal, A request notifying means for receiving a request for channel switching and notifying the request to the base station, and the base station, and determining the switching time and the switching back time according to the request to the mobile terminal. A time notification means for notification, and an acquisition means provided in the mobile terminal for acquiring the notified switching time and switchback time, wherein the synchronization establishment means is provided in the base station. And when the switching time arrives, the mobile terminal is provided with a delivery means for delivering a synchronization signal for establishing synchronization with the second communication channel, and when the switching time arrives, the synchronization signal Is received, and when it is detected, the base station is notified that the synchronization has been established, and the restarting means is provided in the mobile terminal. When the synchronization timing cannot be detected before the switch-back time arrives, the detection means stops the detection of the synchronization timing, and the terminal-side communication means uses the first communication channel. A terminal-side resuming means for resuming communication related to the call, and a notification that the synchronization timing has been detected before the switch-back time comes, provided in the base station If not receiving may comprise a base station-side resuming means for resuming the communication according to the first call using the first communication channel to the base station-side communication means.
[0057]
Further, the agreement means further decides a re-switching time between the mobile terminal and the base station, and the restart means further uses the first communication channel by the communication means using the first communication channel. When communication related to a call cannot be resumed by the time when the re-switching time arrives, the synchronization establishment unit may be caused to try the synchronization establishment again.
[0058]
According to this configuration, the mobile terminal and the base station re-attempt to establish spread code synchronization for communicating the first and second calls in the second communication channel when the re-switching time arrives. The call loss rate can be reduced.
The mobile communication system of the present invention is a CDMA mobile communication system including a mobile terminal and a base station, and the base station uses a first communication channel with the mobile terminal. The first communication means for performing communication related to the first call and the communication related to the first call and the second call in parallel with the communication by the first communication means. Second communication means for performing communication in combination with communication related to the mobile station, wherein the mobile terminal performs communication related to the first call using the first communication channel with the base station. Third communication means to perform, storage means for preliminarily storing the switching time and switchback time, and when the switching time arrives, the third communication means stops communication using the first communication channel, and the second communication means The communication according to the first and the second over the communication channel In order to start communication in combination with communication related to a call, synchronization establishment means that tries to establish synchronization with the base station, and when synchronization cannot be established before the switch-back time arrives Comprises a resuming means for causing the synchronization establishing means to cancel the attempt to establish synchronization and for causing the third communication means to resume communication related to the first call using the first communication channel.
[0059]
According to this configuration, the base station communicates using both the first communication channel and the second communication channel at the same time, while the mobile terminal first communicates with the base station on the first communication channel, and the switching time When communication arrives, the communication of the first communication channel is stopped and an attempt is made to establish spread code synchronization with the base station using the second communication channel. If it cannot be established by the time, communication on the first communication channel is resumed. This eliminates the need for the mobile terminal to negotiate the switching time and switchback time with the base station, and the base station does not need to monitor the arrival of the switching time and switchback time with a timer or the like.
[0060]
Further, the synchronization establishment means further notifies the base station when the synchronization establishment is successful, and the first communication means further communicates when the notification is made by the synchronization establishment means. May be configured to stop.
According to this configuration, the first communication means releases the first communication channel after establishing synchronization in the second communication channel, so that the traffic utilization efficiency is improved.
[0061]
The base station of the present invention is a base station used in a mobile communication system, and is a first communication means for performing communication related to a first call using a first communication channel with a mobile terminal. And, in parallel with the communication by the first communication means, a second communication means for performing communication combining the communication related to the first call and the communication related to the second call with the mobile terminal. Is provided.
[0062]
The mobile terminal of the present invention is a mobile terminal used in a mobile communication system, and performs communication related to the first call with the base station using the first communication channel. Communication means, storage means for preliminarily storing the switching time and switchback time, and when the switching time arrives, the communication means stops communication using the first communication channel, and the communication means uses the second communication channel on the second communication channel. In order to start communication combining the first and second calls, synchronization establishment means for trying to establish synchronization with the base station, and synchronization establishment could not be established before the switch-back time arrives In this case, the communication system includes: restarting means for causing the synchronization establishing means to cancel the attempt to establish synchronization and for causing the communication means to resume communication related to the first call using the first communication channel.
[0063]
The mobile communication method of the present invention is a CDMA mobile communication method performed between a mobile terminal and a base station, and uses a first communication channel between the mobile terminal and the base station. A communication step for performing communication related to the first call, an agreement step for deciding a switching time and a switchback time between the mobile terminal and the base station, and when the switching time arrives, the communication step Communication using one communication channel is stopped, and communication combining the communication related to the first call and the communication related to the second call is started on a second communication channel different from the first communication channel. Therefore, a synchronization establishment step that attempts to establish synchronization between the mobile terminal and the base station, and a synchronization establishment step when synchronization cannot be established before the switch-back time arrives. It stops the attempt to establish synchronization by, and a resumption step of resuming the communication according to the first call using the first communication channel.
[0064]
The mobile communication method of the present invention is a CDMA mobile communication method performed between a mobile terminal and a base station, wherein the base station establishes a first communication channel with the mobile terminal. A first communication step using the first communication to communicate with the mobile terminal in parallel with the communication by the first communication means and the second communication with the mobile terminal; A second communication step of performing communication in combination with communication related to the call, and the mobile terminal communicates with the first call using the first communication channel with the base station. A third communication step for performing the switching, and storing the switching time and the switching back time in the internal memory, and when the switching time arrives, the communication using the first communication channel by the third communication step is stopped, Said first on two communication channels In order to start communication that combines communication and communication related to the second call, a synchronization establishment step that attempts to establish synchronization with the base station, and synchronization establishment is performed before the switch-back time arrives. If not, the step of stopping the synchronization establishment by the synchronization establishment step is stopped, and the third communication step includes a resumption step of resuming the communication related to the first call using the first communication channel. .
[Brief description of the drawings]
FIGS. 1A and 1B show a schematic configuration of a mobile communication system according to the present embodiment and a state of wireless transmission paths before and after HHO performed by the system.
FIG. 2 is a diagram illustrating channel switching by HHO.
FIG. 3 shows a functional block diagram of the mobile terminal 11.
4 is a block diagram showing a configuration of a base station 12. FIG.
FIGS. 5A and 5B are diagrams for explaining operations performed by both the base station 12 and the mobile terminal 11. FIG.
FIG. 6 shows state transitions between the base station 12 and the mobile terminal 11;
FIG. 7 is a diagram for explaining the embodiment;
FIG. 8 is a diagram illustrating a state in which voice communication and packet communication calls are combined and communicated simultaneously.
[Explanation of symbols]
11 Mobile terminal
12 base stations
304 Synchronization monitoring unit
305 Despread code switching unit
306 Despreading unit
307 Unit for reference timing distribution channel
308 HHO front unit
309 HHO after unit
310 Despreading code selector
311 Spreading code selector
312 HHO front unit
313 HHO after unit
314 Spreading code switching unit
315 In-device clock generator
316 clock source
317 monitoring timer
318 channel codec
321 microprocessor
405 Despread code switching unit
406 Despreading unit
407 Unit for reference timing distribution channel

Claims (9)

A CDMA mobile communication system comprising a mobile terminal and a base station, wherein the communication means performs communication related to the first call using the first communication channel between the mobile terminal and the base station. And an agreement means for negotiating a switching time and a switchback time between the mobile terminal and the base station, and when the switching time arrives, the communication means stops communication using the first communication channel, In order to start communication combining the communication related to the first call and the communication related to the second call on a second communication channel different from the first communication channel, the mobile terminal and the base station Synchronization establishment means for trying to establish synchronization between the two communication channels, and when synchronization establishment for communication by the second communication channel has not been established when the switchback time has arrived , the synchronization establishment means Attempt Characterized by stop, the communication relating to the first call using the first communication channel to the communication unit, further comprising a resuming means for resuming to the mobile terminal and the base station in response to the switchback time A mobile communication system.  The communication means is provided in the mobile terminal, and is provided in the base station and terminal-side communication means for performing communication related to a first call using the first communication channel with the base station. The mobile terminal and a base station side communication means for performing communication related to the first call using the first communication channel, and the arrangement means is provided in the mobile terminal, from the user A request notifying means for accepting a channel switching request and notifying the base station of the request, and provided in the base station, determining a switching time and a switching back time according to the request and notifying the mobile terminal Time notification means and an acquisition means provided in the mobile terminal and acquiring the notified switching time and switchback time, and the synchronization establishment means is provided in the base station When the switching time arrives, the mobile terminal is provided with a delivery means for delivering a synchronization signal for establishing synchronization with the second communication channel, and when the switching time comes, the synchronization signal is It is comprised of notification means for notifying the base station that the synchronization timing has been detected by receiving and detecting that the synchronization has been established, and the restarting means is provided in the mobile terminal, If the synchronization timing cannot be detected before the switch-back time arrives, the detection means stops the detection of the synchronization timing, and the terminal-side communication means uses the first communication channel. A terminal-side resuming means for resuming communication related to a call; and a notification provided to the base station that the synchronization timing has been detected before the switch-back time arrives. The base station side resumption means which makes the base station side communication means resume communication related to the first call using the first communication channel when there is no such communication. Mobile communication system.  The negotiating means further negotiates a re-switching time between the mobile terminal and the base station, and the resuming means further accepts the first call using the first communication channel by the communicating means. 2. The mobile communication system according to claim 1, wherein when the communication has not been resumed by the time of the re-switching time, the synchronization establishment unit is made to try the synchronization establishment again. A CDMA mobile communication system comprising a mobile terminal and a base station, wherein the base station performs communication related to a first call using the first communication channel with the mobile terminal. In parallel with the communication by the first communication means and the communication by the first communication means, the first communication means performs communication combining the communication related to the first call and the communication related to the second call with the mobile terminal. 2 communication means, wherein the mobile terminal communicates with the base station using the first communication channel for communication related to the first call, switching time and switching Storage means for preliminarily storing a return time; and when the switching time arrives, the third communication means stops communication using the first communication channel, and the first communication on the second communication channel Communication combined with communication related to the second call To start, the synchronization establishing unit attempts to establish synchronization between the base station, when the switchback time has arrived, if the synchronization establishment for the communication by the second communication channel is not possible The synchronization establishment means cancels the attempt to establish synchronization, and the third communication means performs communication related to the first call using the first communication channel with the mobile terminal and the base as triggered by the switchback time. A mobile communication system comprising restarting means for restarting a station .  The synchronization establishment means further notifies the base station when the synchronization establishment is successful, and the first communication means further stops communication when the synchronization establishment means gives the notification. The mobile communication system according to claim 4, wherein:  5. A base station used in the mobile communication system according to claim 4, wherein a first communication means for performing communication related to a first call using a first communication channel with a mobile terminal; In parallel with the communication by the communication means, the mobile terminal comprises second communication means for performing communication combining the communication related to the first call and the communication related to the second call with the mobile terminal. A base station. 5. A mobile terminal used in the mobile communication system according to claim 4, wherein communication means for performing communication related to the first call using the first communication channel with a base station, and a switching time And storage means for preliminarily storing switchback time, and when the switching time arrives, the communication means stops communication using the first communication channel, and the first and second on the second communication channel. In order to start communication combining calls, synchronization establishment means that attempts to establish synchronization with the base station, and if synchronization cannot be established before the switch-back time arrives, the synchronization A mobile terminal comprising: a resuming unit that causes an establishing unit to cancel an attempt to establish synchronization and to cause the communication unit to resume communication related to the first call using the first communication channel . A CDMA mobile communication method performed between a mobile terminal and a base station, wherein communication related to a first call is performed between the mobile terminal and the base station using a first communication channel. A communication step, an agreement step for deciding a switching time and a switching back time between the mobile terminal and the base station, and when the switching time arrives, the communication using the first communication channel by the communication step is stopped. The mobile terminal and the base for starting communication combining the communication related to the first call and the communication related to the second call on a second communication channel different from the first communication channel a synchronization establishment step of attempting to establish synchronization between the stations Prefecture, when the switchback time has arrived, if you're not establish synchronization for communication by the second communication channel, said synchronization establishment scan Tsu stops the attempt to establish synchronization by flop, the first communication according to the using communication channels first call, and resuming step of resuming a two and mobile terminal and the base station in response to the switchback time mobile communication method which comprises. A CDMA mobile communication method performed between a mobile terminal and a base station, wherein the base station communicates with a first call using a first communication channel with the mobile terminal. In parallel with the communication by the first communication means and the communication by the first communication means, a communication combining the communication related to the first call and the communication related to the second call is performed with the mobile terminal. A second communication step, wherein the mobile terminal performs communication related to the first call using the first communication channel with the base station, and an internal memory the switching time and switching back time remembers, when the switching time arrives, the communication using the first communication channel by the third communication step is stopped, according to the first on the second communication channel Combining communication and communication related to the second call To initiate Align was communication, and synchronization establishment step to attempt to establish synchronization between the base station, when the switchback time is reached, can establish synchronization for communication by the second communication channel Tei If there is not, the attempt to establish synchronization in the synchronization establishment step is stopped, and the mobile communication is triggered by the communication related to the first call using the first communication channel in the third communication step and the switch back time. A mobile communication method comprising: a restart step for restarting a terminal and a base station .

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