Channel switching system

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a channel switching method in a cellular wireless communication (mobile communication) system, and more particularly to a channel switching method in a wireless communication system that controls to match the execution start times of channel switching operations between a base station and a mobile station. ..

【0002】

[Conventional technology]

Communication such as mobile phones is performed by a cellular wireless communication (mobile communication) system. In the cellular system, the communication service area is divided into small zones = cells, and each cell is managed by the base station. A mobile station such as a mobile phone communicates with a base station of a cell to which its own device belongs by controlling multiple access. Multiple access methods include FDMA, TDMA, and CDMA. Further, in the case of the central control system, each base station is collectively controlled by the base station control device. The base station and the base station control device allocate communication channels to each mobile station in the cell to perform communication. For example, in the case of CDMA, a channel is a radio link that is distinguished by a spreading code that differs for each mobile station. Channel allocation methods include static allocation and dynamic allocation. In the case of static allocation, channels are fixedly allocated to base stations and cells. In the case of dynamic allocation, channels are allocated in a time-varying manner according to traffic conditions and the like.

【0003】

The mobile station moves between cells. At that time, it is necessary to control the switching of the base station for communication. This switching control is called handover. Further, although it differs depending on various methods, a scene in which the communication channel must be switched occurs at any time, and a scene in which the channel switching needs to be performed includes the above-mentioned handover. In addition, there are cases where channel switching is performed even within the same cell. The present invention relates to the control of this channel switching.

【0004】

In order to newly set a communication channel between the mobile station and the base station and start communication, it is necessary for both parties to establish synchronization at an appropriate timing. In order to establish this synchronization, as control at layer 3, the base station control device notifies the mobile station and the base station of the execution start time at the time of the channel switching operation, and causes the base station to establish the synchronization based on this timing. (For example, there is "3GPP TS 25.322 V3.6.0" as a wireless communication standard that performs such control). For the execution start time, for example, in the case of W-CDMA, a frame number (FN: Frame Number), which is a common time designation unit for performing synchronization processing between mobile stations, base stations, and base station control devices, is used. Is specified.

【0005】

The channel switching operation in the conventional wireless communication system as described above will be described with reference to FIGS. 6 to 9. FIG. 6 is a diagram showing a basic configuration of a cellular wireless communication system. In FIG. 6, the wireless communication system is composed of a mobile station 1, a base station 2, a base station control device 3, an exchange 4, and another network 5. Base station 2a corresponds to cell a, and base station 2b corresponds to cell b. The mobile station 1 is a terminal such as a mobile phone. The base station 2 performs multiple access control with the mobile station 1 in the corresponding cell to communicate on a predetermined channel. The base station control device 3 controls the base station 2 groups in an integrated manner. The mobile station 1 can be connected to another network 5 via the exchange 4.

【0006】

Hereinafter, in this specification, communication by a W-CDMA (Wideband --Code Division Multiple Access) type mobile phone will be described as an example.

【0007】

FIG. 8 is a sequence diagram showing a normal channel switching operation in the conventional system. Further, FIG. 9 is a sequence diagram showing an operation when channel switching in the conventional system fails. In FIGS. 8 and 9, the configuration of each wireless communication architecture on the mobile station side, the base station, and the base station controller side is largely divided into layers 1, 2, and 3. Layer 1 is related to hardware and physical control in wireless communication. Layer 2 performs communication control over a wireless link, including retransmission control to cover signal loss and the like. Layer 3 performs base station control such as incoming / outgoing communication control and channel switching, and layer 1 and 2 control as wireless communication control of the entire system. The base station 2 is mainly in charge of the layer 1 processing on the base station and the base station control device side, and the base station control device 3 is in charge of the processing of the layers 2 and 3.

【0008】

In FIG. 8, first, it is assumed that the mobile station 1 has started communication with the base station 2a on a predetermined channel. The system causes mobile station 1 to measure the state of wireless communication with base stations around the current cell a. The mobile station 1 reports the measured communication status to the base station control device 3 through the base station 2a.

【0009】

The base station control device 3 monitors the communication status information reported from the mobile station 1 to grasp the position and radio wave condition of the mobile station 1, and appropriately switches to the base station and channel at any time, especially at the cell boundary. To explore. For example, when the mobile station 1 enters the cell boundary, the base station control device 3 determines that it is better to communicate with the base station 2b as the switching destination for the mobile station 1, and then sets the mobile station 1 to the mobile station 1 through the base station 2a. In response, a "channel switching request" signal is transmitted.

【0010】

This "channel switching request" includes "execution start time" information about the channel switching operation in addition to the switching destination channel information and the like. The "execution start time" is the timing information used to establish the synchronization of the radio link between the layer 1 of the mobile station 1 and the layer 1 of the base station 2. This is specified using a frame number, which is a time designation unit for time synchronization processing between a mobile station, a base station, and a base station control device. The frame number is an information element that specifies a certain frame in a predetermined unit period (for example, 2.5 to 2.6 sec). In W-CDMA, this is called FN (Frame Number). One frame is a unit of 10ms. Hereinafter, this "execution start time" information is referred to as T.

【0011】

When transmitting the "channel switching request", the layer 3 of the base station control device 3 first notifies the layer 2 of the transmission request of the "channel switching request (+ T)" signal. At that time, the layer 3 of the base station control device 3 also gives an instruction to the layer 2 to transmit the signal in the mode with confirmation of delivery (AMD: Acknowledged Mode Data). Figure 7 shows the configuration of an example of a signal format with confirmation of delivery (3GPP TS 25.322 V3.6.0 AMD PDU). Layer 2 on the base station and the base station control device side performs a process of adding an information element called "Seqence Number (SN)" indicating a transmission sequence number of the transmission signal to the transmission signal. In the confirmed delivery mode, the SN is used for signal reconstruction and retransmission control. By receiving the delivery confirmation signal for the transmission signal from the mobile station side, the base station and the base station control device side can confirm how far the signal has reached the receiving side.

【0012】

Layer 2 of the base station control device 3 performs a process of adding an information element (such as the transmission number SN) required for retransmission control to the transmission signal in response to a transmission request from the same layer 3. Send to layer 1 of base station 2a. Layer 1 of base station 2a transmits a received signal (channel switching request (+ T)) from layer 2 of base station control device 3 to layer 2 of mobile station 1.

【0013】

Layer 2 of mobile station 1 receives a signal (channel switching request (+ T)) from base station 2a, analyzes information elements (transmission number SN, etc.) added in the layer of base station control device 3, and signals. If there is no problem, the information content is removed, and "reception notification" is sent to layer 3 of mobile station 1. Further, the mobile station 1 layer 2 performs a process of transmitting a delivery confirmation signal for the channel switching request (+ T) from the base station control device 3 to the base station control device 3 layer 2.

【0014】

Layer 2 of the base station control device 3 receives the delivery confirmation signal for the "channel switching request" from the mobile station 1 side, and confirms that the previously transmitted "channel switching request" can be reliably received by the mobile station 1 side. Upon confirmation, the layer 3 is notified of "transmission completed" at this timing.

【0015】

On the other hand, layer 3 of mobile station 1 analyzes that it receives a "channel switching request (+ T)" from layer 3 of base station controller 3, and for mobile station 1 layer 1, the above "execution start time T" Is included in the parameter to notify the "channel switching instruction".

【0016】

When layer 3 of the base station control device 3 receives the "transmission completed" notification for the "channel switching request", it notifies the base station 2b of the "channel activation request" at its execution start time T (notify the mobile station 1). (Same as the execution start time) is sent in the form of including in the parameter.

【0017】

Layer 1 of mobile station 1 is a new channel specified by the parameter included in the instruction when the instructed execution start time T is reached based on the "channel switching instruction (+ T)" from the same layer 3. Switch to, try to establish synchronization with base station 2b, and when synchronization establishment is completed, notify layer 3 of "channel switching completion (synchronization confirmation)". Similarly, layer 1 of the base station 2b also becomes the base station control device 3 when the synchronization establishment with the mobile station 1 based on the "channel activation request (+ T)" from the base station control device 3 is completed. Notify "synchronization confirmation" to it.

【0018】

When layer 3 of the mobile station 1 receives the "channel switching completed" notification from the layer 1, it sends a "channel switching completed" signal indicating that the channel switching is completed to the base station control device 3. When layer 3 of the base station control device 3 receives the "channel switching complete" signal from the mobile station 1 side, it transmits a delivery confirmation signal to the mobile station 1 side and moves to the base station 2a until now. A "channel stop instruction" signal instructing to stop the old channel used for communication with station 1 is transmitted to stop the channel. Channel switching is completed normally by the above procedure.

【0019】

[Problems to be Solved by the Invention]

Hereinafter, the operation that becomes a problem in the above-mentioned conventional channel switching method will be described. FIG. 9 is a sequence diagram showing the operation. Consider the case where the delivery confirmation signal by the mobile station 1 layer 2 for the "channel switching request (+ T)" from the base station controller 3 layer 3 is missing in the radio section and does not reach the base station and the base station controller side. .. At the time of signal transmission, the base station control device 3 layer 2 performs a process of activating a retransmission protection timer for retransmission control. If the delivery confirmation signal for the previously transmitted signal is not returned by the time the protection timer times out by a predetermined limit, the layer 2 performs retransmission processing for the mobile station 1. In this case, the layer 2 of the base station control device 3 retransmits the "channel switching request (+ T)" because the delivery confirmation signal from the mobile station 1 has not arrived and the protection timer has timed out.

【0020】

On the other hand, since the mobile station 1 layer 3 has already received the "channel switching request (+ T)", the "channel switching instruction (+ T)" has been notified to the same layer 1. There is. As a result, the same layer 1 attempts to establish synchronization with the base station 2b for channel switching, but due to the occurrence of the above delivery confirmation signal, the base station 2b side corresponds to the instructed execution start time T. There is a possibility that the "channel activation instruction (+ T)" from the base station control device 3 has not been received. In that case, the channel switching at the execution start time T will fail, and the mobile station 1 layer 3 will be affected. "Channel switching failure (synchronization NG)" is notified.

【0021】

When the mobile station 1 layer 2 receives the signal channel switching request (+ T) resent from the base station control device 3, it returns a delivery confirmation signal again.

【0022】

Assuming that the delivery confirmation signal from the mobile station 1 is normally received in the base station control device 3 layer 1, the layer 3 is notified of "transmission completed". In the base station controller 3 layer 3, when the "transmission completed" notification is received, the "channel activation instruction (+ T)" is notified to the base station 2b, but the mobile station 1 has already been notified in the first signal transmission. If the execution start time T that was instructed has passed and the "channel start instruction" is issued after the execution start time T, between mobile station 1 layer 1 and base station 2b layer 1. Channel switching fails because synchronization cannot be established in, and "synchronization NG" is notified to the base station controller 3. As a result, both the mobile station 1 and the base station control device 3 fail to switch channels.

【0023】

That is, in the above-mentioned conventional method, the base station control device executes the same execution for the mobile station 1 and the base station 2 when the delivery confirmation signal from the mobile station 1 for the "channel switching request" is missing in the radio section. The channel switching operation cannot be performed at the start time. In such a case, channel switching will fail with high probability.

【0024】

With the conventional channel switching method, there is a very high possibility that the channel switching operation will fail when a signal is lost in the wireless section in a mobile station in an environment with poor radio wave conditions, so it is very convenient for the user. It was a bad operation.

【0025】

The present invention has been made in view of such a problem, and a channel switching method capable of reducing the probability of failure of the channel switching operation by performing channel switching control in consideration of the situation of retransmission control in layer 2 is provided. The main purpose is to provide.

【0026】

[Means for solving problems]

In order to achieve such an object, the invention according to claim 1 sets the execution start time of a base station and a mobile station in a cellular wireless communication system including a mobile station, a base station, and a base station control device. It is a channel switching method that performs channel switching control at layer 3 including matching control and retransmission control at layer 2, and layer 2 counts the number of retransmissions of the transmitted signal and assigns it as an information element. The layer 3 dynamically determines the execution start time by grasping the status of the retransmission control in the layer 2 with reference to the retransmission count information and recalculating the execution start time according to the retransmission count. However, it is characterized in that the mobile station and the base station are made to switch channels according to the execution start time.

【0027】

The invention according to claim 2 is the invention according to claim 1, wherein in the mode with confirmation of delivery, the layer 2 particularly relates to a process of counting the number of retransmissions and giving the signal as an information element, and a received signal. The layer 3 has a process of notifying the layer 3 of the delivery confirmation signal with respect to the transmission signal by referring to the information on the number of retransmissions, and the layer 3 determines the execution start time of the channel switching. It is characterized by having a means for performing a process of recalculating and updating the execution start time by referring to the retransmission count information.

【0028】

The invention according to claim 3 is the invention according to claim 1. In the invention according to claim 1, layer 2 uses a protection timer as retransmission control, performs retransmission processing at a timeout within a predetermined limit of the timer, and layer 3 is the execution start time. The recalculation process is characterized by adding a value obtained by multiplying the execution start time by the number of retransmissions and the elapsed time of the timer.

【0029】

The invention according to claim 4 is characterized in that, in the invention according to claim 1, the layer 3 specifies the execution start time by the frame number FN.

【0030】

The invention according to claim 5 is the invention according to claim 1, wherein the layer 3 determines whether or not the transmission signal is a signal related to an instruction of the execution start time, and if the signal uses the execution start time, the layer 2 It is characterized in that it makes a transmission request in a format with delivery confirmation and with information on the number of retransmissions, and otherwise makes a request for transmission in a format without information on the number of retransmissions.

【0031】

The invention according to claim 6 is the invention according to claim 1. In the invention according to claim 1, the layer 3 of the mobile station controls the base station control of the channel switching request signal including the execution start time information and the retransmission count information and the delivery signal confirmation signal for this signal. When received from the device side, the execution start time is recalculated, and the channel switching operation is performed according to the execution start time.

【0032】

The invention according to claim 7 is a layer 3 including a control for matching the execution start times of the base station and the mobile station in a cellular wireless communication system including a mobile station, a base station, and a base station control device. This is a channel switching method that performs channel switching control and retransmission control at layer 2. Layer 3 of the base station control device determines the execution start time of channel switching, with delivery confirmation and retransmission count information. In the step of making a transmission request of the channel switching request in the mode of, and layer 2 of the base station control device in the mode with delivery confirmation, the transmission signal is transmitted by counting the number of retransmissions and adding it as an information element. And layer 2 of the base station controller receives the delivery confirmation signal for the channel switching request from the mobile station, transmits the delivery signal confirmation signal for this signal to the mobile station, and completes the reception of the delivery confirmation signal. And the step of notifying the layer 3 of the retransmission count information included in this signal, and the layer 3 of the base station control device refers to the retransmission count information and recalculates the execution start time according to this information. At the execution start time, the step of instructing layer 1 of the base station to switch channels and layer 3 of the mobile station receive the delivery signal confirmation signal, recalculate the execution start time, and at this execution start time. It is characterized in that it has a step of giving a channel switching instruction to the layer 1 and a step of performing channel switching by the mobile station and the base station at the recalculated execution start time.

【0033】

The invention according to claim 8 is the invention according to claim 7, in which layer 2 uses a protection timer as retransmission control and performs retransmission processing at a timeout within a predetermined limit of the timer, and layer 3 is the execution start time. The recalculation process is characterized by adding a value obtained by multiplying the execution start time by the number of retransmissions and the elapsed time of the timer.

【0034】

The invention according to claim 9 is characterized in that, in the invention according to claim 7, the layer 3 specifies the execution start time by the frame number FN.

【0035】

The invention according to claim 10 is the invention according to claim 7, in which layer 3 determines whether or not the transmission signal is a signal related to an instruction of the execution start time, and if the signal uses the execution start time, layer 2 It is characterized in that it further has a step of making a transmission request in a format with delivery confirmation and with information on the number of retransmissions, and otherwise making a request for transmission in a format without information on the number of retransmissions.

【0036】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a diagram showing a configuration of a wireless communication system using the channel switching method according to the embodiment of the present invention. Further, FIG. 3 is a sequence diagram showing the operation of the channel switching method according to the embodiment of the present invention.

【0037】

In FIG. 1, the wireless communication system using the channel switching method of this embodiment includes a mobile station 1, a base station 2, a base station control device 3, an exchange 4, and another network 5. FIG. 1 illustrates only two sets of base station 2 and the cells it covers. Let each base station be 2a and 2b, respectively, and let the corresponding cells be a and b. In this embodiment, as in the description of the prior art, communication with a W-CDMA mobile phone will be described as an example.

【0038】

This channel switching method is a channel switching method in a wireless communication system that controls the base station and the mobile station to match their execution start times during channel switching control. As a feature of this method, the value of the execution start time, which was conventionally determined only in layer 3, is dynamically determined in consideration of the state of retransmission control in layer 2. As a result, even if a signal is lost in the wireless section during communication during channel switching control and retransmission control is performed, the execution start time is changed accordingly between the mobile station and the base station. Since the execution start times are matched, the channel switching operation can be completed normally.

【0039】

Further, in this method, when the transmission signal from the base station and the base station control device to the mobile station is a signal having nothing to do with the execution start time, the conventional layer 2 format is used and the execution start time is used. For signals that use, use the dedicated Layer 2 format provided by this method. This does not increase Layer 2 overhead.

【0040】

The mobile station 1 is a mobile terminal such as a mobile phone having a predetermined wireless communication function corresponding to a cellular system, code division multiple access, and the like. The base station 2 is a device that processes wireless communication with a mobile station located in the corresponding cell. The base station control device 3 controls the base station 2 groups in an integrated manner, and performs various communication controls including incoming / outgoing control, handover, channel switching control, and the like. The mobile station 1 can be connected to another network 5 through the exchange 4 during communication. The architecture of this wireless communication system is divided into layers 1, 2 and 3, and the main functions and processing are the same as the conventional method.

【0041】

The base station and the layer 3 on the base station control device side have a channel switching control unit that performs predetermined channel switching control based on the conventional method. In this method, the channel switching control unit further includes an execution start time processing unit 6. The execution start time processing unit 6 performs a process of determining the "execution start time" of the mobile station 1 and the base station 2 during the channel switching operation. Further, it is determined whether the transmission signal is a signal with "execution start time", and a transmission request is made to layer 2 by selecting with / without "retransmission count" according to the signal. Further, it is determined whether or not the received signal is a signal with "retransmission count", and the "execution start time" is recalculated with reference to the "retransmission count" value. The "retransmission count" is an element introduced by layer 2 of this method (described later).

【0042】

The base station and layer 2 on the base station control device side have a retransmission control unit that performs predetermined retransmission control based on the conventional method. In this method, the retransmission control unit further includes a retransmission count processing unit 7. The retransmission control unit has a retransmission protection timer function, and starts this protection timer at the time of signal transmission. If the delivery confirmation signal for the transmission signal does not return within the predetermined time limit of the timer and a timeout occurs, the previously transmitted signal is retransmitted. The retransmission count processing unit 7 provides a "Retry Count" information element as a format of the transmission signal, and performs a process of counting the number of retransmissions and assigning the transmission signal as an information element. The retransmission count value is set to, for example, 0 in the normal state without retransmission, and is incremented each time retransmission is performed. FIG. 2 shows the format of the layer 2 mode signal with delivery confirmation (AMD PDU (Acknowledged Mode Data Protocol Data Unit)) of this method provided with the retransmission count information element. Except for the Retry Count field, the elements are the same as the signal format shown in the conventional method.

【0043】

Layer 2 of the base station control device 3 generates an acknowledged mode data according to the instruction of the layer 3, and transmits the signal from the layer 1. Further, when the layer 2 receives the delivery confirmation signal from the mobile station side, the layer 2 notifies the layer 3 of "transmission completed" indicating that the previous transmission signal is certainly transmitted to the mobile station side. At the time of this notification, the retransmission count value is also notified.

【0044】

As described in the conventional method, the "execution start time" information is the timing information for channel switching and synchronization establishment specified by the information such as the frame number FN. Hereinafter, this "execution start time" information element is referred to as T.

【0045】

The mobile station 1 side also has a processing unit that performs processing corresponding to the processing performed by the execution start time processing unit of the base station and the layer 3 on the base station control device side and the retransmission count processing unit of the layer 2.

【0046】

The operation of the channel switching method according to the embodiment of the present invention will be described with reference to FIGS. 3, 4, and 5. The sequence diagram of FIG. 3 shows the operation when a signal loss occurs in the radio section and the delivery confirmation signal from the mobile station 1 does not reach the base station control device 3 side.

【0047】

First, it is assumed that the mobile station 1 has already started communication with the base station 2a on a predetermined channel. The system causes the mobile station 1 to measure the wireless communication status with the base stations around the cell in which the current position is located, and to report to the base station controller 3 through the base station 2a. The base station control device 3 monitors the communication status information reported from the mobile station 1, and searches for the switching destination base station and the switching destination channel at any time based on the position of the mobile station 1, the radio wave condition, and the like. Here, it is assumed that the need for channel switching for mobile station 1 has occurred. For example, when the mobile station 1 enters the cell boundary, it is assumed that the base station control device 3 determines that the communication with the base station 2b is better as the switching destination. Based on this judgment, the base station control device 3 determines the switching destination channel and the execution start time T of the channel switching operation, and sends a "channel switching request" signal to the mobile station 1 through the base station 2a with a delivery confirmation function. Send in format.

【0048】

FIG. 4 shows a flowchart of the layer 3 transmission / reception processing of the base station control device 3. First, the base station control device 3 layer 3 includes "execution start time" information in the signal transmitted to the mobile station 1 (here, "channel switching request") at the start of the transmission process (step S1). Check if (step S2). If the signal does not include the execution start time information, the layer 2 is notified of the transmission request in the format as in the conventional method (no retransmission count) (step S3). If the signal includes execution start time information, the layer 2 is notified of the transmission request in the format with "Retry Count" together with the information such as the execution start time T instructed to the mobile station 1. (Step S4). After the notification, wait for the "transmission completed" notification from Layer 2 (step S5).

【0049】

FIG. 5 shows a flowchart of the transmission / reception process with the retransmission count of the layer 2 of the base station control device 3. When layer 2 of the base station control device 3 receives a notification from the same layer 3 of "a transmission request specified with a retransmission count (including an instruction of execution start time T)" (step S11), the information element "RetryCount" Is first initialized (step S12), a transmission signal with a retransmission count and a delivery confirmation function is generated (step S13), and is transmitted to the mobile station 1 by the same layer 1 (step S14). At this time, the retransmission protection timer is started. Then, it waits for the reception of the delivery confirmation signal with respect to the transmission signal (step S15).

【0050】

In FIG. 3, the signals with (1st) and (2nd) are signals to which the retransmission count is given. (1st) indicates the first transmission, RetryCount = 0, (2nd) indicates the second transmission, that is, the first retransmission, and RetryCount = 1. In the above procedure, the "channel switching request (+ T)" signal is transmitted from the base station and the base station controller side to the mobile station 1 side. When the layer 2 of the mobile station 1 receives the signal with the retransmission count, the layer 2 adds the RetryCount value as an information element and returns the delivery confirmation signal. At this timing, layer 2 of mobile station 1 does not perform "reception notification" regarding the channel switching request to layer 3.

【0051】

If this delivery confirmation signal is lost in the radio section, layer 2 of the base station controller 3 retransmits the signal (here, "channel switching request (+ T)") at the timing of the timeout of the retransmission protection timer. At this time, the RetryCount value is counted up (here, 0 1) (Fig. 5, step S16), and retransmission is performed.

【0052】

Layer 2 of the mobile station 1 sets the retry count again in response to the received signal (second channel switching request) from the base station control device 3 and transmits the delivery confirmation signal. As with the first time, "receipt notification" is not performed.

【0053】

When the layer 2 of the base station control device 3 normally receives the delivery confirmation signal from the mobile station 1, the layer 2 refers to the RetryCount value included in the signal and refers to the signal retransmitted by the layer 2 (second channel switching request). It confirms that it is a delivery confirmation signal, and transmits a "delivery signal confirmation signal" indicating that the delivery confirmation signal has been surely received to the mobile station 1 including the execution start time T and the retryCount value. In addition, the layer 3 is notified of "transmission completed" for the channel switching request together with the retryCount value (Fig. 5, step S18).

【0054】

Layer 3 of the base station control device 3 determines whether or not the received signal from the same layer 2 is a "transmission completed" notification with a retransmission count (Fig. 4, step S6), and notifies "transmission completed (+ RetryCount value)". In the case of, in order to update the execution start time T determined at the beginning (at the time of the first transmission) according to the retransmission status, refer to the RetryCount value (step S7), and the execution start time T based on that value. Perform the recalculation process (step S8). Let T'be the recalculated execution start time. Calculate with T'= T + α. α is obtained by multiplying the RetryCount value (here, the value is 1 because one retransmission is performed) by the interval time of one retransmission processing, that is, the elapsed time t of the protection timer in FIG. That is, T'= T + RetryCount × t.

【0055】

Layer 3 of the base station controller 3 notifies layer 1 of the base station 2b of the "channel switching instruction" including the instruction of the new recalculated execution start time T'(= T + α). To switch channels.

【0056】

On the other hand, in layer 2 of the mobile station 1, when the "delivery signal confirmation signal (+ T, RetryCount)" is received from the base station control device 3, "reception notification" for the channel switching request is sent to the layer 3. At that time, the RetryCount value is also notified. When the mobile station 1 layer 3 receives the "reception notification" from the same layer 2, the retryCount value is updated in order to update the execution start time T according to the retransmission status in the same manner as the processing in the base station controller 3 layer 3. Recalculate the execution start time T with reference to. If the recalculated execution start time is T', it is calculated by T'= T + α = T + RetryCount × t. t is the elapsed time associated with one retransmission process. The mobile station 1 layer 3 notifies the layer 1 of the "channel switching instruction" including the new T'instruction to perform channel switching. Since the execution start time is determined in consideration of the number of retransmissions by layer 2, both the mobile station 1 side and the base station 2 side can establish synchronization within the execution start time, and channel switching is completed normally. be able to.

【0057】

After that, the process is the same as the conventional one. The mobile station 1 layer 1 and the base station 2 layer 1 each perform channel switching at the recalculated execution start time T'. When mobile station 1 layer 1 succeeds in establishing synchronization, it transmits "channel switching complete (synchronization confirmation)" to the same layer 3. When the base station 2 layer 1 succeeds in establishing synchronization, it transmits "channel switching completion (synchronization confirmation)" to the base station controller 3 layer 3. When the mobile station 1 layer 3 receives the "channel switching completed" from the same layer 1, it transmits the "channel switching completed" to the base station controller 3 layer 3. When the base station controller 3 layer 2 receives the "channel switching complete", it notifies the layer 3 of the "reception notification" of the channel switching completion. Upon receiving this "reception notification", the layer 3 transmits a delivery confirmation signal for the previous "channel switching completed" to the mobile station 1 layer 3, and also sends a "channel stop instruction" to the base station 2. To stop the old channel. As described above, the channel switching operation can be normally completed even when the retransmission control is performed.

【0058】

Other application examples of this method will be described. In the above embodiment, the case of channel switching between base stations has been described, but this can also be applied to the case of channel switching within the same cell. Also, when processing to change the parameters of the channel being communicated, for example, when changing the communication speed (data rate) during packet communication, the execution start time for the control is set in the same manner. Therefore, the operation can be performed by using the transmission request signal with the retransmission count as in the above-described embodiment, and the probability of failure of the operation can be reduced.

【0059】

The embodiment of the present invention has been described above. It should be noted that the above-described embodiment shows an example of a preferred embodiment of the present invention, and the present invention is not limited thereto, and various modifications can be carried out within a range not deviating from the gist thereof. ..

【0060】

[Effect of the invention]

As is clear from the above description, according to the present invention, signal processing is completed within the execution start time when a signal is lost in a wireless section in a mobile station with poor radio wave conditions during channel switching control. It is possible to improve the channel switching operation, which has a high probability of failure due to failure, by changing the channel switching operation in consideration of the situation of retransmission control at layer 2, to increase the success probability and improve the communication service quality. .. In addition, by defining a new layer 2 signal format for that purpose and using the conventional layer 2 format for other signals that are not related to execution start time matching control, this effect is achieved without increasing the overhead of layer 2. Can be realized.

[Simple explanation of drawings]

[Figure 1]

It is a figure which shows the structure of the wireless communication system which uses the channel switching system in embodiment of this invention.

[Figure 2]

It is a figure which shows the format of the mode signal with delivery confirmation by the method of this invention.

[Fig. 3]

It is a sequence diagram which shows the operation of the channel switching system in embodiment of this invention.

[Fig. 4]

It is a flowchart which shows the transmission / reception processing of layer 3 of a base station control device.

[Fig. 5]

It is a flowchart which shows the transmission / reception processing with the retransmission count of the layer 2 of a base station control device.

[Fig. 6]

It is a figure which shows the structure of the wireless communication system which uses the conventional channel switching method.

[Fig. 7]

It is a figure which shows the signal format with the delivery confirmation by the conventional method.

[Fig. 8]

It is a sequence diagram which shows the normal channel switching operation in the conventional method.

[Fig. 9]

It is a sequence diagram which shows the failure of the channel switching operation at the time of occurrence of retransmission in the conventional method.

[Explanation of symbols]

1 mobile station 2a, 2b base station 3 Base station controller 4 exchange 5 Other networks cell a, b 6 Execution start time processing unit 7 Retransmission count processing unit