KR20040056586A - Method for managing transmission timing of down-link transport channel in wcdma system - Google Patents

Abstract

PURPOSE: A method for managing the transmission timing of a DL(DownLink) transport channel in a WCDMA system is provided to increase the data quality of a system by preventing a traffic frame, transmitted to a base station from a base station controller, from being out of synchronization, reducing the burdens of the base station controller and the base station for buffer management, and eliminating an excessive transmission delay. CONSTITUTION: If a transmission timing management function for DL transport channels begins after node synchronization(S600), a base station controller checks every TTI(Transmission Time Interval) whether frames to be sent to a DL are stored in a queue(S601). If stored frames exists in the DL queue, the base station controller copies a CFN(Connection Frame Number) value from a DL data frame stored in the last of the queue, makes a DL synchronization frame using the value, and stores it in the last of the queue(S603). If the base station sends the DL synchronization frame to a base station, the CFN of the sent frame is stored. At this moment, a standby timer is set a much as Twus(Timer for wait_ul_sync), and the base station controller waits for a UL(UpLink) synchronization frame(S604). If a UL synchronization frame is received(S606), the base station controller checks whether the CFN of the frame is matched with the CFN of the sent DL synchronization frame(S607). If the CFN of the UL synchronization frame is matched with the CFN of the DL synchronization frame, the base station controller reads the TOA(Time Of Arrival) value of the received frame, adjusts the TOA value so as to come close to the central value of an Rx window, and maintains the best DL frame transmission timing(S609).

Description

Method of managing transmission timing of downlink transport channel in asynchronous mobile communication system {METHOD FOR MANAGING TRANSMISSION TIMING OF DOWN-LINK TRANSPORT CHANNEL IN WCDMA SYSTEM}

The present invention relates to a method for managing transmission timing of a downlink transport channel in an asynchronous mobile communication system. More particularly, the present invention relates to synchronization of traffic frames of a downlink transport channel in an asynchronous mobile communication system using a wideband code division multiple access method. It relates to a transmission timing management method for maintaining a.

Synchronization of downlink transport channels in an asynchronous mobile communication system (WCDMA system) using a wideband code division multiple access method requires a node synchronization process that finds a relationship between a control station and a base station. . When node synchronization is performed between the control station and the base station by the node synchronization process, the control station may transmit a traffic frame to the base station so that the traffic frame arrives at a desired time (receive window). If a call occurs after a node synchronization process and a transport channel for traffic transmission is formed, transport channel synchronization is maintained for the transport channel. This is the synchronization of the downlink transport channel.

Downlink propagation in the synchronized transport channel may gradually transition out of the receiving window area to the de-synchronized state according to the increase and decrease of the call and the amount of traffic change.

As a conventional technique for correcting the occurrence of the demotor is a timing adjustment (Timing Adjustment) procedure. This is to re-establish synchronization at the next transmission time by adjusting the downlink transmission time in the desynchronized transport channel. As such a timing adjustment method, "a method of calculating a connection frame number (CFN) for transmission channel synchronization between a control station and a base station in an IMT-2000 asynchronous system" is referred to as Korean Patent Application No. It was filed in 2001-0082884 (filed November 30, 2001).

The above-mentioned patent application discloses a DOFF, LTOA, TOAWS, TOAWE value, which is a information received by a traffic handling module (THM) when a call is set up from a T1, T2, and call control processor by node synchronization between a control station and a base station. Obtain a system time conversion factor that can calculate the CFN of the frame to be sent from the control system's current system time, and when the frame is configured in the traffic handling module of the control station, Add the conversion factor to calculate the CFN of the frame to set the transmission time. At this time, if the transport channel is out of synchronization due to a change in the load on the wireless access network, the synchronization is restored by changing the system time switching factor by the amount of out of synchronization. However, this method has a disadvantage in that it does not prevent the de-motive in advance. Therefore, there is a need for a method of preventing the de-motive in advance through synchronous monitoring of the transport channel periodically, but has not been applied to the conventional system.

In another conventional technique, "Effect of Timing Adjust Algorithm on Iub Link Capacity for Voice Traffic in WCDMA Systems" by S. Abraham, A. Sampath, C. Saraydar, M. Chuah was published in VTC (October 2002). Published.

The technique of the preceding paper proposes an algorithm that can improve the efficiency of transport channel synchronization and reduce the timing adjustment procedure by providing an appropriate transmission delay between the base station and the control station by presenting and analyzing an appropriate reception window. However, in the above paper, only voice traffic is considered, and thus, there is a problem in that it cannot cope with multimedia service traffic and can not cope with multiple paths of handover.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described technical problem, and has a synchronization function that allows a traffic frame transmitted from a control station of an asynchronous mobile communication system to a base station to arrive at an appropriate time in a traffic processing module of the base station. Downlink transport channels that can be deflected by traffic changes between the base station and the base station to prevent desynchronization in some cases, thereby reducing the burden on the buffer management of the base station and the control station and eliminating excessive transmission delays, thereby improving the data quality of the system. An object of the present invention is to provide a transmission timing management method.

1 is a view showing a schematic configuration of an asynchronous mobile communication system to which the present invention is applied.

2 is a view for explaining the synchronization of the transport channel in the transmission timing management method of the downlink transport channel according to the present invention.

3 is a diagram illustrating a reception window of a base station in a method for managing transmission timing of a downlink transport channel according to the present invention;

4 is a diagram illustrating a timing adjustment process in a transmission timing management method of a downlink transport channel according to the present invention.

5 is a diagram illustrating a timing monitoring process in a method for managing transmission timing of a downlink transport channel according to the present invention.

6 is a flowchart showing a processing flow of a method for managing transmission timing of a downlink transport channel according to the present invention;

(Explanation of symbols for the main parts of the drawing)

10: mobile station 11: base station

12: control station

Transmission timing management method of the downlink transport channel according to the present invention for achieving the above object,

A traffic handling module of a mobile communication control station that accommodates wireless traffic processing selects a group of transport channels grouped by transmission time intervals applied to a transport channel as one management target, and periodically transports channels for each management target. The first step of performing a synchronous check,

And a second step of readjusting the transport channel transmission time by using the result of the synchronization check process.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 shows a schematic configuration of an asynchronous mobile communication system to which the present invention is applied.

As shown in FIG. 1, the asynchronous mobile communication system to which the present invention is applied includes a mobile station 10 in which a user is a portable communication terminal, a base station 11 wirelessly connected to a plurality of mobile terminals 10, and the plurality of base stations. Control station 12 for controlling (11).

A transmission timing management method for maintaining synchronization of downlink transport channel traffic frames in an asynchronous mobile communication system having such a configuration will be described below with reference to FIGS. 2 to 6.

2 is a diagram illustrating synchronization of a transport channel in a method for managing transmission timing of a downlink transport channel according to the present invention.

In order to synchronize downlink transport channels in an asynchronous mobile communication system using a wideband code division multiple access scheme, a node synchronization process for finding out the relationship of time between the control station 12 and the base station 11 is performed. This is necessary. When a node is synchronized between the control station 12 and the base station 11 by the node synchronization process, the control station 12 is a traffic frame at a time (receive window) desired by the base station 11 with respect to the base station 11. You can send this to arrive. If a call occurs after a node synchronization process and a transport channel for traffic transmission is formed, transport channel synchronization is maintained for the formed transport channel. This is the synchronization of the downlink transport channel. In the synchronized transport channel, a downlink (DL) data frame 20 transmitted by the control station 12 to the base station 11 is expected by the base station 11. It arrives at the reception window 21 and the frame is transmitted to the terminal 10 via radio. In FIG. 2, a frame is attached with a connection frame number (CFN), which is a connection frame number for synchronization of layer 2 and transport channels of the mobile station 10 and the control station 12, and the frame is received by the base station 11. To be processed, the base station 11 arrives at the base station 11 within the period of the reception window 21 set for the frame. Time of Arrival (TOA) 22 is the time at which the frame was received, indicating how far from the end of the receive window 21.

3 illustrates a reception window of a base station in a method for managing transmission timing of a downlink transport channel according to the present invention.

As shown in FIG. 3, the reception window includes a LTOA (Latest Time Of Arrival) 30, a TOAWS (TOA Window Startpoint) 31, and a TOAWE (TOA Window Endpoint). Window end point). Here, the value of the LTOA 30 means the time required for the base station 11 to process a frame received from the control station 12 and fly to the radio channel, and the control station 12 as a system parameter of the base station 11 This value is known from the system configuration. The TOAWS 31 and the TOAWE 32 are parameters that designate start and end points of the reception window, and are determined by the control station 12 to inform the base station 11 at the beginning of call setup.

When the frame is transmitted through the synchronized transport channel through the above process, it is gradually missed due to the change of traffic between the control station 12 and the base station 11, so that in some cases, a deactivator is generated. In this case, a method for resynchronization is shown in FIG. 4.

4 illustrates a timing adjustment process in a transmission timing management method of a downlink transport channel according to the present invention.

As shown in FIG. 4, if the DL data frame 40 transmitted from the control station 12 to the base station 11 does not reach within the reception window of the base station 11, the base station 11 receives the control station 12. The timing adjustment frame 41 is transmitted to the control station 12, and the control station 12 adjusts the transmission time using the value of TOA, which is a time parameter in the timing adjustment frame, to ensure accurate timing from the next frame.

On the other hand, the timing adjustment method shown in FIG. 4 cannot be prevented in advance because it is a procedure performed after the deactivator occurs. Therefore, FIG. 5 shows a method of periodically monitoring the synchronization of the transport channel and preventing the desynchronizer in advance.

5 illustrates a timing monitoring process in a transmission timing management method of a downlink transport channel according to the present invention.

In FIG. 5, when the control station 12 transmits the DL synchronization frame 50 to the base station 11, the base station 11 that has received it measures the time at which the received frame arrives, and within the reception window held by itself. The control station 12 responds with a TOA value that is a time interval. In FIG. 5, when the DL synchronization frame 50 properly arrives in the reception window and the TOA has a positive value, the DL synchronization frame 50 has a negative value when the DL synchronization frame 50 is delayed than the reception window. The control station 12 receiving the UL (Up-Link) uplink frame 51 including the TOA adjusts the downlink transmission timing according to the value of the received TOA.

The synchronization process of the downlink transport channel shown in FIG. 2 to FIG. 5 is configured for each transport channel. Thus, in view of the fact that the link between the base station 11 and the control station 12 is a cluster of several transport channels, all the transmissions on the link with respect to the change of the link between the base station 11 and the control station 12. Because the port channel is affected, desynchronization procedures occur frequently, which adversely affects the performance of the system. On the other hand, the example of the timing monitoring process described in Fig. 5 is not applied to the conventional system.

Therefore, in order to solve such a problem, in the present invention, the mobile communication control station 12 selects a transport channel group grouped by transmission time interval (TTI) applied to the transport channel as one management object. The transport timing of the transport channel is managed by a first step of performing a periodic transport channel synchronization check for each management object and a second step of re-adjusting the transport channel transmission time using the result of the synchronization check process. Describe how to do it.

The processing flow of the transmission timing management method of the downlink transport channel according to the present invention is shown.

In the asynchronous mobile communication system to which the transmission timing management method of the downlink transport channel according to the present invention is applied, the traffic processing module of the control station 12 is composed of a transmission timing management entity and a downlink transmission management entity. The timing management entity is configured to periodically monitor and adjust the transmission timing of downlink transport channels with which the downlink transmission management entity has. The transmission timing management entity classifies and manages a downlink transport channel as a management object. The managed transport channel group includes all transport channels using the same transmission time interval (TTI) among the plurality of transport channels assigned to one independent base station 11. It is a set. By selecting the management target in this way, it is possible to maintain independence from the management target channel group having different TTIs, thereby simplifying the control. Therefore, the transport channel allocated to the other base station 11 at the time of handover belongs to another management object, so that the control of the multiple paths at the time of handover is independent.

6 shows a case of one managed transport channel group. In FIG. 6, when the transmission timing management function of the downlink transport channel starts after node synchronization is finished (S600), whether a frame queue to be transmitted to the downlink (DL) every TTI is stored, that is, the DL queue. It is checked whether is empty (S601). If there is a frame in the queue, the CFN value is copied from the DL data frame stored at the end of the queue, and the value is used to create a DL synchronization frame. The generated DL synchronization frame is stored at the end of the queue (S603). If the queue is checked in step S601 and there are no frames in the queue, the time passes by a predetermined time Tdelta (S602), and then the queue is checked again (S601). By doing so, since the CFN calculation of a given transport channel is performed by the downlink frame transmission management entity, the calculation amount of the transmission timing management entity can be reduced. The predetermined time Tdelta in the step S602 may be arbitrarily determined within a range not exceeding the transmission time interval TTI among values corresponding to an integer multiple of 125 microseconds as a waiting time for checking the state of the queue.

On the other hand, when the control station 12 transmits the DL synchronization frame to the base station 11 in step S603, the connection frame number (CFN) of the transmitted frame is stored, and the waiting time by Twus (Timer for wait_ul_synch). The timer is set. Next, the UL synchronization frame waits (S604). Since the value of Twus is the response time of the base station 11 with respect to the frame transmitted by the control station 12, it can be determined using the time parameter obtained in the node synchronization process.

If the timer is expired because the UL synchronization frame is not received (S605), after waiting for the transmission time interval (TTI) (S610), it returns to a new start (S600).

When the control station 12 receives the UL synchronization frame (S606), it checks the CFN value in the frame and checks whether it matches the CFN (Tx_CFN) of the previously transmitted DL synchronization frame (S607). If the CFN (Rx_CFN) of the UL synchronization frame received in step S607 and the CFN (Tx_CFN) of the transmitted DL synchronization frame do not match, the received frame is discarded (S608) and the operation after the step (S610) This is repeated. If the CFN (Rx_CFN) of the UL synchronization frame received from the control station 12 in step S607 matches the value of the transmitted CFN (Tx_CFN), the value of the TOA in the received frame is read, and the TOA value is Adjust to approximate median to maintain the best downlink frame transmission timing. That is, a time shift value for adjusting the transmission time of the management target transport channel is calculated, and this value is transmitted to the downlink frame transmission management entity to adjust the transmission time (S609).

Next, it is checked whether the value of TOA in the reception frame is outside the point of TOAWS 32 or LTOA 31 of the reception window, that is, the TOA is appropriate (S611). If the TOA is a proper value in step S611, the AC counter is reset (S612), waits for the transmission time interval TTI (S613), and returns to a new start (S600). If the TOA is not an appropriate value in step S611, the AC counter is incremented (S614), and it is checked whether the AC counter value has reached a threshold (S615). The AC counter is a cumulative counter, the value of which is an integer selected to satisfy the frame error rate (FER) of the system. If the AC counter value falls below the threshold in step S615, the operation after step S613 is repeated. When the AC counter value reaches the threshold in step S615, the frame transmitted from the control station 12 to the base station 11 has not been properly transmitted, and thus sends an alert and performs node synchronization again (S616). The transmission timing management function of the downlink transport channel is terminated (617). Thereafter, if resynchronization is performed by node synchronization, a new start (S600) is performed by starting the transmission timing management function of the downlink transport channel.

As described above, the method of the present invention may be implemented as a program and stored in a computer-readable recording medium.

While the invention has been described above based on the preferred embodiments thereof, these embodiments are intended to illustrate rather than limit the invention. It will be apparent to those skilled in the art that various changes, modifications, or adjustments to the above embodiments can be made without departing from the spirit of the invention. Therefore, the protection scope of the present invention will be limited only by the appended claims, and should be construed as including all such changes, modifications or adjustments.

As described above, the present invention manages transmission timing for maintaining synchronization of downlink transport channel traffic frames in an asynchronous mobile communication system using a wideband code division multiple access method, and transmits the control station of the mobile communication system to the base station. By allowing one traffic frame to arrive at the appropriate time in the traffic processing module of the base station, the burden on the buffer management of the base station and the control station is reduced, and excessive transmission delay is eliminated, thereby improving the data quality of the system.

Claims (4)

A transmission timing management method of a downlink transport channel in an asynchronous mobile communication system using a wideband code division multiple access method, A first step in which a mobile communication control station selects a group of transport channels grouped by transmission time intervals applied to a transport channel as a management target, and performs a synchronization check of a transport channel periodically for each management target; , And a second step of readjusting a transmission time of a transport channel using a result of the first step of the synchronization check process. A method of managing transmission timing of a downlink transport channel in an asynchronous mobile communication system. The method of claim 1, The first step is Copy the value of the link frame number from the last downlink data frame of the queue in which the frame to be transmitted to the downlink is stored at each transmission time interval, and use the value to create a downlink synchronization frame, and the downlink synchronization frame is Lastly stored and transmitted to the base station A method of managing transmission timing of a downlink transport channel in an asynchronous mobile communication system. The method of claim 1, The second step is Adjusting the transmission timing of the management channel using the TOA (Time Of Arrival) value in the frame received from the base station, and performs synchronization recovery by re-synchronizing the node using the cumulative counter for the excessively missed frame doing A method of managing transmission timing of a downlink transport channel in an asynchronous mobile communication system. A method of managing transmission timing of a downlink transport channel in an asynchronous mobile communication system using a wideband code division multiple access method, The mobile communication control station selects a group of transport channels grouped by transmission time intervals applied to the transport channel as one management target, and performs a periodic check on the transport channel for each management target. , A program for realizing a second function of rescheduling the transmission time of the transport channel by using the result of the synchronization checking process is recorded Computer-readable recording media.