WO2009084083A1

WO2009084083A1 - Gateway device and data transfer method

Info

Publication number: WO2009084083A1
Application number: PCT/JP2007/075107
Authority: WO
Inventors: Chigusa Miyahara; Hidefumi Takaoka; Hideki Nagino
Original assignee: Fujitsu Limited
Priority date: 2007-12-27
Filing date: 2007-12-27
Publication date: 2009-07-09

Abstract

A gateway device and a data transfer device, with which a packet transmitted from a core network is transferred to a radio base station. Residence of the packet due to advance of time of the gateway device is speedily dissolved after time of the gateway device is corrected to correct time. When second reception time of a second data packet received last time from the core network is later than first reception time of a first data packet received this time from the core network, transmission time of the second packet is ignored and transmission time of the first packet is calculated.

Description

Gateway device and data transfer method

The present invention relates to a gateway device and a data transfer method for transferring a data packet sent from a core network toward a radio base station.

In recent years, a wireless communication system protocol called 3G (3rd generation) has been widely adopted.

This 3G also has several stages of development. In addition to the original 3G adopted by FOMA and others, mobile phones adopting a protocol called 3.5G or HSDPA with higher communication speed have also appeared. Currently, a protocol called Super3G or 3.9G is being studied.

This Super3G system provides a service (MBMS; Multimedia Broadcast / Multimedia Service) that simultaneously distributes image data such as streaming broadcasts to a large number of mobile users. For example, streaming broadcast data distributed by a core network streaming broadcast server is simultaneously distributed simultaneously to a plurality of wireless mobile station devices via a gateway device as multicast packet data. In order to simultaneously distribute the multicast packets, a time stamp (transmission start time) is required, and the gateway device has a function of calculating a time stamp and giving a time stamp value to the packet. The radio base station apparatus that has received the multicast packet keeps the packet until the time of the time stamp, and transmits the packet to a large number of radio mobile station apparatuses at the time of the time stamp.

FIG. 1 is a schematic diagram of a communication system that performs MBMS.

Here, a core network 10, a gateway device 20, a plurality of radio base station devices 30, and a radio mobile station device 40 such as a mobile phone are shown. The core network 10 has the configuration shown in FIG. , Connected to a LAN (Local Area Network), a content server 11 for high-speed and large-capacity file transfer, a content server 12 for streaming transmission, a SIP server 13 for managing voice calls, and an NTP (Network Time Protocol for managing the current time) ) Server 14 is included. The

content servers

11 and 12 and the SIP server 13 transmit multicast packets (here, these multicast packets are collectively referred to as MBMS packets), and the MBMS packets are received by the gateway device 20 with a time stamp and wirelessly transmitted. It is transmitted to the base station device 30. The radio base station device 30 transmits the MBMS packet to the radio mobile station device 40 at the same time when the time stamp is reached.

Here, the gateway device 20 receives the NTP packet representing the current time from the NTP client 14 and corrects the time. In addition, the radio base station apparatus 30 performs time correction by GPS (Global Positioning System).

FIG. 2 is a diagram illustrating a hardware configuration related to time adjustment of the gateway device 20.

The NTP server 14 manages an accurate current time, and an NTP packet representing the current time is input to the gateway device 20 via the LAN.

The gateway device 20 also manages the current time, but since the current time managed by the gateway device 20 has a large error, the current time is corrected based on the received NTP packet.

The gateway device 20 includes a CPU 21, a memory 22, a clock 23, and a LAN interface 24. The memory 22 stores NTP client software.

The current time of the gateway device 20 is managed based on the clock generated by the clock 23.

The NTP client software is executed by the CPU 21, analyzes the NTP packet received by the LAN interface 24, and corrects the current time managed by the gateway device 20 based on the NTP packet.

FIG. 3 is a flowchart showing a time stamp calculation processing flow performed by the gateway device.

When the gateway device 20 receives the MBMS packet (step S10), the reception time T (x) of the MBMS packet is acquired based on the current time managed by the gateway device 20 (step S11). Here, x of T (x) is the serial number of the MBMS packet received this time (denoted as MBMS packet (x)), and x-1 described later is the serial number of the MBMS packet (x-1) received last time. It is shown that.

next,
L_time (x-1) <T (x) + Tdelay (1)
Is satisfied (step S12).

Here, L_time (x-1) represents the scheduled completion time of transmission of the previously received MBMS packet (x-1) from the radio base station device 30 to the radio mobile station device 40. This scheduled transmission completion time is discretized in units of MTI representing the transmission cycle, which is obtained in step S15 described later when the flow of FIG. 3 is executed for the previously received MBMS packet (x−1). It's time. The transmission cycle MTI will be described later with reference to FIG.

Further, Tdelay in the expression (1) is a radio frequency when the gateway device 20 transmits the MBMS packet to the radio base station device from the reception time of the MBMS packet and immediately prepares for transmission at the radio base station device. The estimated time until the preparation for transmission in the base station apparatus is completed (this is called a delay time here) is shown.

Therefore, in step S12, the transmission time T (x) + Tdelay of the current MBMS packet is later than the scheduled transmission completion time when the transmission of the previous MBMS packet (x-1) at the radio base station apparatus is completed. It is determined whether (Yes) or not (No).

When the expression (1) is satisfied, that is,
L_time (x-1) <T (x) + Tdelay
Means that there is a time margin between the previous MBMS packet (x-1) and the current MBMS packet (x). In this case, the radio base station apparatus should be notified this time The MTI unit value immediately after the time of T (x) + Tdelay is obtained as TS (x) which is a time stamp indicating the transmission start time of the MBMS packet (x) from the radio base station apparatus (step S13). Details of step S13 will be described later.

On the other hand, if it is determined in step S12 that the above equation (1) is not satisfied, the process proceeds to step S14. In this case, it means that the previous MBMS packet (x−1) and the current MBMS packet (x) have arrived at the gateway device successively. In this case, the current MBMS to be notified to the radio base station device. TS (x), which is a time stamp indicating the transmission start time of the packet (x) from the radio base station apparatus, is sent from the radio base station apparatus to the radio mobile station apparatus in the previous MBMS packet (x-1). Is scheduled to be transmitted (time stamp value L_Time (x−1) discretized in MTI units. Details of step S14 will be described later.

In step S15, the transmission completion time (time stamp value) L_Time (x) of the current MBMS packet (x) is obtained for calculation at the time of reception of the next MBMS packet (x + 1). In step S16, the current MBMS packet (X) is transmitted toward the radio base station apparatus with the time stamp value TS (x) obtained in step S13 or step S14.

FIG. 4 is step S12 of FIG.
L_time (x-1) <T (x) + Tdelay
It is a figure which shows the packet transmission / reception timing chart of the state which satisfies and progresses to step S13.

In this figure, the horizontal axis represents the passage of time, and the vertical line on the horizontal axis represents the passage of the time for each transmission cycle MTI. In FIG. 4 (and each diagram showing a packet transmission / reception timing chart described later), MTI = 10 msec (hereinafter, all units of msec are omitted).

In FIG. 4 (and each diagram showing a packet and a reception timing chart described later), in order from the top, MBMS packets are transmitted / received at the gateway device, transmitted / received at the wireless base station device, and received at the wireless mobile station device. Timing is shown.

The previous packet (x-1) is received by the gateway device at time 32, and is transmitted to the radio base station device with a transmission start time stamp TS (x-1) = 60. In the radio base station apparatus, the packet (x-1) is held until the time of TS (x-1) = 60, and when the time of TS (x-1) = 60 is reached, the radio base station apparatus It is transmitted toward the wireless mobile station device. The transmission end time of this packet (x-1) from the radio base station apparatus to the radio mobile station apparatus is within the time stamp of time 60, and transmission completion discretized by MTI in step S15 of FIG. Time L_time (x−1) = 70 is obtained.

The packet (x) is received by the gateway device at the reception time T (x) = 58. Here, Tdelay = 20 is set as the delay time Tdelay, and the equation (1) is
L_time (x−1) = 70 <T (x) + Tdelay = 58 + 20 = 78
Thus, the determination condition in step S12 in FIG. 3 is satisfied.

In this case, the time stamp TS (x) = 80 next to the time stamp (70) including T (x) + Tdelay = 78 as the transmission start time for starting transmission from the radio base station device to the radio mobile station device is The packet is set, and the time stamp TS (x) = 80 is attached to the packet (x) and sent to the radio base station apparatus. In the radio base station apparatus, the packet (x) sent from the gateway apparatus waits until the time stamp TS (x) = 80 and transmits it to the radio mobile station apparatus by radio.

On the other hand, if it is determined in step S12 of FIG.

FIG. 5 is a diagram showing a packet transmission / reception timing chart in a state in which the process proceeds to step S14 without satisfying the determination criterion in step S12.

The case where the above formula (1), which is the criterion of step S12, is not satisfied, as shown in FIG. 5, the current packet (x) is sent to the gateway device following the previous packet (x-1). This is the case. In this case, in step S14 of FIG. 3, the current packet (x) has the same time as the transmission completion time of the previous packet (x-1) (discrete value in time stamp units) L_time (x-1) = 70. The stamp TS (x) = 70 is attached and sent to the radio base station apparatus. The radio base station apparatus transmits the previous packet (x−1) at time 60 and the current packet (x) at time 70. To do.

Here, as described above, the radio base station apparatus performs time correction by GPS, and always has an accurate time. However, the gateway device obtains the time from the NTP server, and when the time correction frequency of the NTP server is low, or even if the correction frequency is high, the NTP server is discarded or stopped due to a high load or some trouble. When this occurs, the time managed by the gateway device may be shifted.

FIG. 6 is a diagram showing a packet transmission / reception timing chart when the time of the gateway device is ahead of the accurate time of the radio base station device.

Suppose that an MBMS packet (x) arrives at the gateway device at time 68 and is sent to the radio base station device with TS (x) = 90 as a transmission start time stamp. In this case, since the radio base station apparatus waits until the time 90 for the packet (x) and transmits the packet (x) to the radio base station apparatus, the residence time in the radio base station apparatus is increased by the advancement of the time of the gateway apparatus. When the phenomenon of lengthening occurs and a large number of packets are continuously transmitted, a large number of packets stay in the radio base station apparatus, and the possibility of packet discarding or the like increases.

FIG. 7 is a diagram showing a packet transmission / reception timing chart when the time of the gateway device is corrected to an accurate time from the state where the time of the gateway device is advanced as shown in FIG.

The packet (x−1) arrives at the gateway device at time 70 at the time of the gateway device, and is sent to the radio base station device with a transmission start time TS (x−1) = 90. Thereafter, it is assumed that the time of the gateway device is corrected to an accurate time, and then the packet (x) arrives at the gateway device.

In this case, according to the flowchart of FIG. 3, since the criterion of the expression (1) in step S12 is not satisfied, the process proceeds to step S14, and the transmission start time TS (x) of the packet (x) is set as the previous packet (x− 1) The transmission completion time L_time (x−1) = 100 and the same time TS (x) = 100 are added, and the phenomenon that the residence time in the radio base station apparatus is long is the correct time of the gateway apparatus. It will continue until it is corrected to the time.

Although Cited Document 1 discloses a technique for detecting a congestion state of a network and changing a transmission rate, it does not solve the stagnation that accompanies a time lag of the wireless base station device.
Japanese Patent Laid-Open No. 11-112305

The present invention has been made in view of the above circumstances, and aims to quickly eliminate the retention of packets caused by the advance of the gateway device time after the gateway device time is corrected to the correct time. To do.

The first gateway device of the gateway devices of the present invention that achieves the above object has been sent from a core network including a content server that is responsible for transmitting data packets and an NTP server that is responsible for transmitting NTP packets representing the current time. A gateway device that receives a data packet, attaches a transmission start timestamp indicating the transmission start time of the data packet from the radio base station to the radio mobile station, and transmits the data packet to the radio base station. And
A time management unit that manages the current time and receives the NTP packet to correct the current time;
Based on the current time managed by the time management unit, a reception time acquisition unit that acquires the reception time of the data packet sent from the core network;
Delay prediction until a data packet is transmitted to the radio base station at the reception time of the data packet acquired by the reception time acquisition unit, and the radio base station is ready to transmit the data packet to the radio mobile station By adding time, a transmittable time predicting unit that predicts a transmittable time of the data packet from the radio base station, and
The first condition that the first data packet received this time from the core network is a time after the transmittable time predicted by the transmittable time prediction unit, and the first condition received last time from the core network and transmitted to the radio base station A time stamp calculation unit for obtaining the transmission start time stamp that satisfies both of the second condition that the time is a time after the scheduled transmission completion time of the data packet of 2 from the radio base station to the radio mobile station;
The transmission completion schedule for the first data packet is added by adding the estimated transmission time required for transmission of the data packet at the radio base station to the transmission start time represented by the transmission start time stamp obtained by the time stamp calculation unit. A transmission completion time prediction unit for obtaining the time,
The time stamp calculation unit has a time later than the first reception time of the first data packet received this time from the core network and the second reception time of the second data packet previously received from the core network. In this case, the transmission start time stamp is obtained based only on the first condition of the first condition and the second condition.

The first gateway device of the present invention is corrected from the time at which the gateway device time is advanced to an accurate time, and from the core network before the first reception time of the first data packet received this time from the core network. When the second reception time of the received second data packet is later, the transmission start time is based on only the first condition among the first condition and the second condition. Since the stamp is obtained, the retention of the packet is quickly eliminated after the time of the gateway device is changed to an accurate time.

In addition, the second gateway device of the gateway devices of the present invention receives data packets sent from a core network including a content server responsible for transmitting data packets and an NTP server responsible for transmitting NTP packets representing the current time. A gateway device that receives the data packet and transmits it to the radio base station with a transmission start time stamp indicating the transmission start time of the data packet from the radio base station to the radio mobile station;
A time management unit that manages the current time and receives the NTP packet to correct the current time;
Based on the current time managed by the time management unit, a reception time acquisition unit that acquires the reception time of the data packet sent from the core network;
Delay prediction until data packet is transmitted to the radio base station at the reception time of the data packet acquired by the reception time acquisition unit, and the radio base station is ready to transmit the data packet to the radio mobile station By adding time, a transmittable time predicting unit that predicts a transmittable time of the data packet from the radio base station, and
The first condition that the first data packet received this time from the core network is a time after the transmittable time predicted by the transmittable time prediction unit, and the first condition received last time from the core network and transmitted to the radio base station A time stamp calculation unit for obtaining the transmission start time stamp that satisfies both of the second condition that the time is a time after the scheduled transmission completion time of the data packet of 2 from the radio base station to the radio mobile station;
The transmission completion schedule for the first data packet is added by adding the estimated transmission time required for transmission of the data packet at the radio base station to the transmission start time represented by the transmission start time stamp obtained by the time stamp calculation unit. A transmission completion time prediction unit for obtaining a time;
When the second reception time of the second data packet previously received from the core network is later than the first reception time of the first data packet received this time from the core network, the wireless base station A transmission for obtaining a new transmission start time of the second data packet from the station to the radio mobile station, and transmitting a correction notification packet instructing the radio base station to correct the new transmission start time A time correction unit,
In response to the transmission time correction unit obtaining a new transmission start time for the second data packet, the transmission completion time prediction unit performs a new transmission from the radio base station to the radio mobile station for the second data packet. The transmission completion prediction time is obtained, and the time stamp calculation unit has a first condition that the time is a time after the transmission possible time predicted by the transmission possible time prediction unit of the first data packet received this time from the core network, Satisfy both of the second condition that the second data packet received last time from the core network and transmitted to the radio base station is a time after the predicted new transmission completion time from the radio base station to the radio mobile station. The transmission start time stamp is obtained.

According to the second gateway device of the present invention, the previous time from the core network is earlier than the first reception time of the first data packet received this time from the core network, which is corrected to the accurate time from the time when the time of the gateway device has advanced. When the second reception time of the received second data packet is later, not only the packet after the time correction but also the packet sent to the radio base station before the time correction Also, the transmission start time is corrected, and packet retention is eliminated more quickly.

A first data transfer method of the data transfer method of the present invention that achieves the above object is a core server including a content server responsible for data packet transmission and an NTP server responsible for transmission of an NTP packet representing the current time. The received data packet is received, and the data packet is transmitted to the radio base station with a transmission start time stamp indicating the transmission start time of the data packet from the radio base station to the radio mobile station. A data transfer method comprising:
A time management step for managing the current time and receiving the NTP packet to correct the current time;
A reception time acquisition step of acquiring the reception time of the data packet sent from the core network based on the current time managed by the execution of the time management step;
Delay prediction until a data packet is transmitted to a radio base station at the reception time of the reception time acquisition step and the radio base station is ready to transmit the data packet to the radio mobile station A transmission time predicting step for predicting a transmission time of the data packet from the radio base station by adding time; and
The first condition that the first data packet received this time from the core network is a time after the transmittable time predicted in the transmittable time prediction step, and the first condition received last time from the core network and transmitted to the radio base station A time stamp calculation step for obtaining the transmission start time stamp satisfying both of the second condition that the time is a time after the scheduled transmission completion time of the data packet of 2 from the wireless base station to the wireless mobile station;
By adding the estimated transmission time required for data packet transmission at the radio base station to the transmission start time represented by the transmission start time stamp obtained in the time stamp calculation step, the transmission completion schedule for the first data packet is scheduled. A transmission completion time prediction step for obtaining a time,
In the time stamp calculating step, the second reception time of the second data packet previously received from the core network is later than the first reception time of the first data packet received this time from the core network. The transmission start time stamp is obtained based on only the first condition out of the first condition and the second condition.

Furthermore, a second data transfer method of the data transfer method of the present invention that achieves the above object is provided from a core network including a content server responsible for data packet transmission and an NTP server responsible for transmission of an NTP packet representing the current time. The received data packet is received, and the data packet is transmitted to the radio base station with a transmission start time stamp indicating the transmission start time of the data packet from the radio base station to the radio mobile station. A data transfer method comprising:
A time management step for managing the current time and receiving the NTP packet to correct the current time;
A reception time acquisition step of acquiring the reception time of the data packet sent from the core network based on the current time managed by the execution of the time management step;
Delay prediction until a data packet is transmitted to a radio base station at the reception time of the reception time acquisition step and the radio base station is ready to transmit the data packet to the radio mobile station A transmission time predicting step for predicting a transmission time of the data packet from the radio base station by adding time; and
The first condition that the first data packet received this time from the core network is a time after the transmittable time predicted in the transmittable time prediction step, and the first condition received last time from the core network and transmitted to the radio base station A time stamp calculation step for obtaining the transmission start time stamp satisfying both of the second condition that the time is a time after the scheduled transmission completion time of the data packet of 2 from the wireless base station to the wireless mobile station;
By adding the estimated transmission time required for data packet transmission at the radio base station to the transmission start time represented by the transmission start time stamp obtained in the time stamp calculation step, the transmission completion schedule for the first data packet is scheduled. A transmission completion time prediction step for obtaining a time;
When the second reception time of the second data packet previously received from the core network is later than the first reception time of the first data packet received this time from the core network, the wireless base station A transmission for obtaining a new transmission start time of the second data packet from the station to the radio mobile station, and transmitting a correction notification packet instructing the radio base station to correct the new transmission start time A time correction step,
In response to the fact that a new transmission start time of the second data packet has been obtained in the transmission time correction step, the transmission completion time prediction step performs a new transmission from the radio base station to the radio mobile station for the second data packet. The transmission completion prediction time is obtained, and the time stamp calculation step includes a first condition that the time is a time after the transmission available time predicted by the transmission available time prediction unit of the first data packet received this time from the core network, Satisfy both of the second condition that the second data packet received last time from the core network and transmitted to the radio base station is a time after the predicted new transmission completion time from the radio base station to the radio mobile station. And a step of obtaining a transmission start time stamp.

According to the above configuration, packet retention is quickly eliminated after time correction.

It is a schematic diagram of the communication system which performs MBMS. It is a figure which shows the hardware constitutions regarding the time adjustment of a gateway apparatus. It is a flowchart which shows the time stamp calculation processing flow which a gateway apparatus performs. FIG. 4 is a diagram illustrating a packet transmission / reception timing chart in a state in which L_time (x−1) <T (x) + Tdelay is satisfied in step S12 of FIG. 3 and the process proceeds to step S13. It is a figure which shows the packet transmission / reception timing chart of the state which progresses to step S14, without satisfy | filling the criterion in step S12. It is a figure which shows the packet transmission / reception timing chart in case the time which a gateway apparatus has has advanced rather than the exact time which a wireless base station apparatus has. It is a figure which shows the packet transmission / reception timing chart when the time of the gateway apparatus is correct | amended from the state which the time of the gateway apparatus shown in FIG. 6 is advanced to the exact time. It is a figure which shows the time stamp calculation process flow performed within the gateway apparatus of 1st Embodiment of this invention. It is a figure which shows the packet transmission / reception timing chart in 1st Embodiment. It is a figure which shows the packet transmission / reception timing chart in case 1st Embodiment transmits many packets. It is a figure which shows the time stamp calculation process flow performed within the gateway apparatus of 2nd Embodiment of this invention. It is a figure which shows the packet transmission / reception timing chart in 2nd Embodiment shown in FIG.

Hereinafter, embodiments of the present invention will be described.

In the following, only the differences from the conventional gateway apparatus described so far will be described, and the points not described will follow the configuration of the conventional gateway apparatus as they are.

FIG. 8 is a diagram showing a time stamp calculation processing flow executed in the gateway device of the first embodiment of the present invention.

In the flow shown in FIG. 8, steps denoted by the same reference numerals as those in steps S10 to S16 in the flow shown in FIG. 3 are the same as those in the flow shown in FIG. 3. In FIG. 8, steps S21 to S23 are performed. Has been added.

In step S21, since T (x) <T (x-1), the reception time T (x) of the current packet (x) is greater than the reception time T (x-1) of the previous packet (x-1). It is determined whether it is time to return. When the reception time has not returned (No), step S22 is skipped and the process proceeds to step S23, and T (x) is set for the determination process in step S21 when the next packet (x + 1) is received. Saved to T (x-1), the process proceeds to step S12.

When the reception time is returned (Yes), the process proceeds to step S22, and the transmission completion time L_time (x-1) of the previous packet (x-1) is calculated as L_time (x-1). ) = 0, and then the process proceeds to step S23.

When it is determined in step S21 that T (x) <T (x-1), since L_time (x-1) = 0 is set in step S22, in this case, in step S12,
L_time = 0 <T (x) + Tdelay
Therefore, this conditional expression is always satisfied, and the process proceeds to step S13. In step S13, the transmission completion time of the previous packet (x-1) is ignored, and a value (MTI unit value) obtained by adding the delay time Tdelay to the reception time T (x) of the current packet (x) is obtained.

FIG. 9 is a diagram showing a packet transmission / reception timing chart in this case.

The transmission start time TS (x-1) of the packet (x-1) before time correction is TS (x-1) = 90, and time correction is performed after reception of the packet (x-1). It is assumed that the current packet (x) is received at the time of T (x) = 48 after correction.

In this case, since T (x) + Tdelay = 48 + 20 = 68, the transmission start time TS (x−1) = 90 of the packet (x−1) is not considered here, and the transmission of the packet (x) is not considered. TS (x) = 70 is obtained as the start time TS (x).

In this case, the transmission order of the packet (x) and the packet (x−1) from the radio base station apparatus to the radio mobile station apparatus is reversed, but the radio mobile station apparatus uses the sequence number of the received packet. It is an interface that performs sequence control, and there is no problem.

FIG. 10 is a diagram showing a packet transmission / reception timing chart when a large number of packets are transmitted / received in the first embodiment.

In FIG. 10, packets (x-2) and (x-1) are received before time correction, and packets (x), (x + 1), (x + 2),..., (N) are received after time correction. Indicates the state. The transmission start time stamps of the packets (x), (x + 1),..., (N) received after the time correction are reversed from the transmission start time stamps of the received packets before the time correction, as shown in FIG. Although there is a possibility that the values are the same, order control is performed in the radio mobile station apparatus, and information is transmitted to the user of the radio mobile station apparatus in the correct order.

FIG. 11 is a diagram showing a time stamp calculation processing flow executed in the gateway device according to the second embodiment of the present invention.

As in the case of the flow of FIG. 8, in the flow shown in FIG. 11, the steps denoted by the same reference numerals as steps S10 to S16 in the flow shown in FIG. 3 are the same as the steps in the flow shown in FIG. In FIG. 11, steps S31 to S35 are added compared to the flow shown in FIG.

In step S31, as in step S21 of FIG. 8, it is determined whether or not the reception time has returned by T (x) <T (x−1). If the reception time has not returned, steps S32 and S33 are performed. Skip to step S34. In step S34, as in step S23 of FIG. 8, T (x) is saved to T (x-1) for the determination process in step S31 when the next packet (x + 1) is received, and in step S12. move on.

On the other hand, when it is determined in step S31 that the reception time has returned, the process proceeds to step S32, and in this step S32,
TS (x-1)> T (x) + Tdelay (2)
Is satisfied.

TS (x−1) in equation (2) is the previous packet (x−1) calculated before time correction saved in step S35 when the previous packet (x−1) was received. ), And T (x) + Tdelay is obtained by adding the delay time Tdelay to the reception time after the time correction of the packet (x). x), the transmission start time of the previous packet (x−1) is later than the transmission start possible time (T (x) + Tdelay) from the radio base station apparatus to the radio mobile station apparatus. It is determined whether or not.

If the expression (2) is not satisfied, it means that the order of transmission times of packets from the radio base station apparatus to the radio mobile station apparatus does not reverse. In this case, step S33 is skipped and step S34 is skipped. move on.

If it is determined in step S32 that the expression (2) is satisfied, the process proceeds to step S33.

In step S33, the transmission start time stamp TS (x-1) of the previous packet (x-1) is recalculated to the shortest time that the radio base station apparatus can transmit, taking into account the corrected current time, Along with this, the transmission completion time L_time (x-1) of the packet (x-1) is also recalculated, and the transmission start time stamp of the packet (x-1) is recalculated this time toward the radio base station apparatus. A modification notification packet instructing modification to the transmitted transmission start time stamp TS (x−1) is transmitted.

When the recalculation is performed in step S33, the value after the recalculation in step S33 is adopted as the transmission completion time L_time (x-1) of the previous packet (x-1) in steps S12 and S14.

In step S35, the transmission start time stamp TS (x) of the current packet (x) obtained in step S13 or step S14 is set to TS (for the processing in steps S32 and S33 when the next packet (x + 1) is received. Saved as x-1).

FIG. 12 is a diagram showing a packet transmission / reception timing chart in the second embodiment shown in FIG.

The previous packet (x-1) is received before the time correction, and the transmission start time stamp TS (x-1) = 90 is added and sent to the radio base station apparatus. Time correction is performed after receiving the packet (x-1), and then the current packet (x) is received.

At this time, the transmission start time stamp TS (x−1) is recalculated for the previous packet (x−1) and notified to the radio base station apparatus, and the radio base station apparatus receives the notification and receives the previous packet (x−1). The transmission start time of (x-1) is corrected from TS (x-1) = 90 to TS (x-1) = 60.

Also,
The scheduled transmission end time L_time (x-1) of the current packet (x-1) is calculated in accordance with the recalculation of the transmission start time stamp TS (x-1) for the previous packet (x-1). Therefore, the transmission start time stamp TS (x) of the current packet (x) is calculated as TS (x) = 70, and TS (x) = 70 is added to the current packet (x), so that the radio base station apparatus Sent to.

In the case of this second embodiment, when a time return occurs, the transmission start time stamp TS (x-1) of the previous packet (x-1) is recalculated to a value that does not stay in the radio base station apparatus as described above. And notified to the radio base station apparatus. Since the transmission start time stamp TS (x) of the current packet (x) is also calculated using the transmission completion scheduled time L_time (x-1) after the recalculation of the previous packet (x-1), A value that does not stay in the base station apparatus is set. As described above, in the case of the second embodiment, the problem of packet retention is solved without causing reversal of the transmission order of packets from the radio base station apparatus to the radio mobile station apparatus.

Claims

Receives a data packet sent from a core network including a content server responsible for data packet transmission and an NTP server responsible for transmission of an NTP packet representing the current time, and receives the data packet from the wireless base station to the wireless mobile station A gateway device that transmits a transmission start time stamp indicating a transmission start time of the data packet to the radio base station,
A time management unit for managing the current time and receiving the NTP packet to correct the current time;
Based on the current time managed by the time management unit, a reception time acquisition unit that acquires the reception time of the data packet sent from the core network;
Until the reception time of the data packet acquired by the reception time acquisition unit is transmitted to the radio base station and preparation for transmitting the data packet to the radio mobile station is completed. By adding the estimated delay time, a transmittable time predicting unit that predicts the transmittable time of the data packet from the radio base station,
The first condition that the first data packet received this time from the core network is a time after the transmittable time predicted by the transmittable time predicting unit, and the previous condition received from the core network and transmitted to the radio base station A time stamp calculation unit for obtaining the transmission start time stamp that satisfies both of the second condition that the second data packet is a time after the scheduled transmission completion time from the radio base station to the radio mobile station;
By adding the estimated transmission time required for data packet transmission at the radio base station to the transmission start time represented by the transmission start time stamp obtained by the time stamp calculation unit, the first data packet for the first data packet, A transmission completion time prediction unit for obtaining a transmission completion scheduled time,
The time stamp calculation unit is a time later than the first reception time of the first data packet received from the core network this time, the second reception time of the second data packet received last time from the core network. The gateway apparatus is characterized in that the transmission start time stamp is obtained based only on the first condition out of the first condition and the second condition.
Receives a data packet sent from a core network including a content server responsible for data packet transmission and an NTP server responsible for transmission of an NTP packet representing the current time, and receives the data packet from the wireless base station to the wireless mobile station A gateway device that transmits a transmission start time stamp indicating a transmission start time of the data packet to the radio base station,
A time management unit for managing the current time and receiving the NTP packet to correct the current time;
Based on the current time managed by the time management unit, a reception time acquisition unit that acquires the reception time of the data packet sent from the core network;
Until the reception time of the data packet acquired by the reception time acquisition unit is transmitted to the radio base station and preparation for transmitting the data packet to the radio mobile station is completed. By adding the estimated delay time, a transmittable time predicting unit that predicts the transmittable time of the data packet from the radio base station,
The first condition that the first data packet received this time from the core network is a time after the transmittable time predicted by the transmittable time predicting unit, and the previous condition received from the core network and transmitted to the radio base station A time stamp calculation unit for obtaining the transmission start time stamp that satisfies both of the second condition that the second data packet is a time after the scheduled transmission completion time from the radio base station to the radio mobile station;
By adding the estimated transmission time required for data packet transmission at the radio base station to the transmission start time represented by the transmission start time stamp obtained by the time stamp calculation unit, the first data packet for the first data packet, A transmission completion time prediction unit for obtaining a transmission completion scheduled time;
When the second reception time of the second data packet previously received from the core network is later than the first reception time of the first data packet received this time from the core network, the wireless base station A transmission for obtaining a new transmission start time of the second data packet from the station to the radio mobile station, and transmitting a correction notification packet instructing correction to the new transmission start time to the radio base station A time correction unit,
In response to the transmission time correction unit obtaining a new transmission start time of the second data packet, the transmission completion time prediction unit transmits the second data packet from the radio base station to the radio mobile station. The time stamp calculating unit calculates the new transmission completion predicted time of the first data packet received this time from the core network, and is the time after the transmittable time predicted by the transmittable time predicting unit. And a second condition that the second data packet received last time from the core network and transmitted to the radio base station is a time after a new predicted transmission completion time from the radio base station to the radio mobile station, and A gateway apparatus characterized in that the transmission start time stamp satisfying both of the above is obtained.
Receives a data packet sent from a core network including a content server responsible for data packet transmission and an NTP server responsible for transmission of an NTP packet representing the current time, and receives the data packet from the wireless base station to the wireless mobile station A data transfer method for transmitting to a radio base station with a transmission start time stamp indicating a transmission start time of the data packet,
A time management step of managing the current time and receiving the NTP packet to correct the current time;
A reception time acquisition step of acquiring a reception time of a data packet sent from the core network based on a current time managed by execution of the time management step;
Until the reception time of the data packet acquired in the reception time acquisition step, the data packet is transmitted to the radio base station, and the radio base station is ready to transmit the data packet to the radio mobile station A transmission possible time prediction step for predicting a transmission possible time of the data packet from the radio base station by adding a delay prediction time of
The first condition that the first data packet received this time from the core network is a time after the transmittable time predicted in the transmittable time prediction step, and the previous condition received from the core network and transmitted to the radio base station A time stamp calculation step for obtaining the transmission start time stamp satisfying both of the second condition that the second data packet is a time after the scheduled transmission completion time from the radio base station to the radio mobile station;
The transmission start time represented by the transmission start time stamp obtained in the time stamp calculation step is added with a predicted transmission time required for data packet transmission at the radio base station, whereby the first data packet is A transmission completion time prediction step for obtaining a transmission completion scheduled time,
In the time stamp calculation step, the second reception time of the second data packet previously received from the core network is later than the first reception time of the first data packet received this time from the core network. In this case, the data transfer method is a step of obtaining the transmission start time stamp based only on the first condition out of the first condition and the second condition.
Receives a data packet sent from a core network including a content server responsible for data packet transmission and an NTP server responsible for transmission of an NTP packet representing the current time, and receives the data packet from the wireless base station to the wireless mobile station A data transfer method for transmitting to a radio base station with a transmission start time stamp indicating a transmission start time of the data packet,
A time management step of managing the current time and receiving the NTP packet to correct the current time;
A reception time acquisition step of acquiring a reception time of a data packet sent from the core network based on a current time managed by execution of the time management step;
Until the reception time of the data packet acquired in the reception time acquisition step, the data packet is transmitted to the radio base station, and the radio base station is ready to transmit the data packet to the radio mobile station A transmission possible time prediction step for predicting a transmission possible time of the data packet from the radio base station by adding a delay prediction time of
The first condition that the first data packet received this time from the core network is a time after the transmittable time predicted in the transmittable time prediction step, and the previous condition received from the core network and transmitted to the radio base station A time stamp calculation step for obtaining the transmission start time stamp satisfying both of the second condition that the second data packet is a time after the scheduled transmission completion time from the radio base station to the radio mobile station;
The transmission start time represented by the transmission start time stamp obtained in the time stamp calculation step is added with a predicted transmission time required for data packet transmission at the radio base station, whereby the first data packet is A transmission completion time prediction step for obtaining a transmission completion scheduled time;
When the second reception time of the second data packet previously received from the core network is later than the first reception time of the first data packet received this time from the core network, the wireless base station A transmission for obtaining a new transmission start time of the second data packet from the station to the radio mobile station, and transmitting a correction notification packet instructing correction to the new transmission start time to the radio base station A time correction step,
In response to the fact that the new transmission start time of the second data packet has been obtained in the transmission time correction step, the transmission completion time prediction step is performed from the radio base station to the radio mobile station for the second data packet. The time stamp calculating step is a time that is the time after the transmittable time predicted by the transmittable time predicting unit of the first data packet received this time from the core network. And a second condition that the second data packet received last time from the core network and transmitted to the radio base station is a time after a new predicted transmission completion time from the radio base station to the radio mobile station, and A data transfer method characterized by the step of obtaining the transmission start time stamp satisfying both of the above.