JPH10308753A - Communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a radio terminal that has much processing including handover, etc., easily signal to an AAL type 2, also making a band efficient and to efficiently send each call, considering the characteristic of the radio terminal and a network. SOLUTION: A buffering part 11 has plural buffers 11a, 11b,... which accumulate transmission data from radio terminals and have different retention allowable times. The buffers 11a, 11b,... whose retention allowable times agree to the retention allowable time of transmission data store corresponding transmission data, and accumulated transmission data are sent out to a network side from the buffers 11a, 11b,... in order of short retention allowable time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication apparatus that performs a call acceptance process and a priority control in an ATM adaptation layer when, for example, a wireless terminal supporting multimedia performs communication via an ATM network.

[0002]

2. Description of the Related Art Until now, wireless terminals have been used for mobile phones and PHSs.
(Personal Handyphone System
em) mainly deals with voice. Recently, a system that can also transmit data like PHS has been considered, but since the transmission speed is exactly the same as that of voice, it is common to treat it as traffic when viewed from the network side. . Therefore, the same band should be allocated to all terminals to perform circuit-switching processing.

However, recently, wideband CDMA (Co
de Division Multiple Access
ss) has attracted attention. Wideband C
It is considered that DMA not only performs multimedia communication such as voice and data, but also supports different transmission speeds depending on the medium. For example, voice varies from several kbps to several tens of kbps depending on the encoding method, while the data is up to 2 Mbps.
need to support up to s. It is extremely difficult to process the line in a time-division manner, and especially, the data rate is not always constant at the peak rate, so that waste increases.

As a method for supporting such variable-rate multimedia information, ATM (Asynch) is used.
There is a so-called “rouble transfer mode” communication. ATM technology is the most suitable infrastructure for handling multimedia. In the ATM technology, line multiplexing is performed using fixed-length packets called ATM cells. One ATM cell can hold 48 bytes of information, but this is inefficient and inadequate for handling small items such as voice. Therefore, it has been devised to multiplex information of a plurality of users into one ATM cell. This is AAL (ATM Adapt)
ation Layer) type 2. In AAL type 2, since a user shares one ATM cell, a normal signaling message in Layer 3 is not used directly, but ANP (AAL2 Negot) is used.
It is considered to be able to accommodate a simple call by using an ANP, but the details of ANP have not been determined yet.

Also, calls accommodated using ANP have different traffic characteristics, so priority control of information transmission is required according to the traffic characteristics. However, there is no fixed method at present.

[0006]

As described above, as described above, AN
There has been no standard established for call acceptance using P and priority control in AAL type 2.

[0007] The present invention has been made in view of this point, and an object of the present invention is to provide a simple and bandwidth-efficient signaling to AAL type 2 for a wireless terminal that frequently performs call processing including handover. And to perform efficient transmission control for each call in consideration of the characteristics of the wireless terminal and the network.

[0008]

According to an aspect of the present invention, there is provided a communication apparatus comprising: a plurality of buffers for accumulating transmission data from a wireless terminal and having different allowable permissible times; Means are provided for accumulating the transmission data in the buffer having the allowable residence time matching the allowable time, and means for transmitting the stored transmission data to the network side in order from the buffer having the shortest allowable residence time. For example, at least one is a system in which a wireless terminal communicates using AAL type 2, wherein the arrival period of a wireless frame, which is a unit of data transmission from the wireless terminal, is p, the wireless base station of data transmitted from the wireless terminal Permissible time for each application of m types q [x]
(X = 1,2,3, ..., m), for each q [x], q
t [y] in ascending order of all positive values obtained by subtracting p one or more times from [x] and q [x], excluding duplicates
(Y = 1, 2, 3,..., N), n buffers are created for each t [y], and the transmission data from the wireless terminal has the same value of t [y] as its staying tolerance. In the buffer, data is sent to the network side in order from the buffer having the smallest value of t [y].

According to a second aspect of the present invention, there is provided the communication apparatus according to the first aspect, wherein the permissible dwell time of a buffer having a permissible dwell time longer than a period at which transmission data arrives from a wireless terminal is set to the permissible period. A means for cyclically changing each cycle by the cycle. For example, the value of t [y] in the buffer is updated every period p in which data from the next wireless terminal arrives, and a buffer having a value of t [y] larger than p is t [y] −p Is replaced by the value of
Buffers with the following values of t [y] are t [y] and t
Among [y] plus a multiple of p, it has the same value as the application's residence allowance and the largest q
[x], and t [y] (y = 1, y = 1,
2, 3,..., N).

A communication device according to a third aspect of the present invention is the communication device according to the first aspect, wherein the free space of the buffer is calculated based on the amount of data currently stored in the buffer and the amount of data currently stored in the buffer based on the permissible time of the buffer. It is a value obtained by subtracting the amount of data currently stored in the buffer having the shorter allowable residence time. For example, the buffer having the value of t [1] has a value obtained by subtracting the amount of data currently stored in the buffer from the amount of data that can be transmitted during the period t [1] as a free buffer capacity, The buffer having the value of t [y] (y = 2, 3,..., N) is calculated based on the t [z] (z = 1,. )) Has a value obtained by subtracting the sum of the amounts of data already stored in the buffers having the values of (1) and (2), and has a free buffer capacity management.

According to a fourth aspect of the present invention, there is provided a communication apparatus for storing a plurality of buffers for storing transmission data from a network, the plurality of buffers having a permissible residence time of an integral multiple of a predetermined time unit, and a permissible residence time matching the permissible residence time of said transmission data Means for storing the transmission data in the buffer, and means for transmitting the stored transmission data to the wireless terminal in order from the buffer having the shorter permissible residence time. For example, in a system in which at least one of the wireless terminals communicates using AAL type 2, the transmission period of a wireless frame, which is a unit of data transmission to the wireless terminal, is p, and the exchange terminating the ATM adaptation layer type 2 is p. When the permissible residence time for data for wireless terminals is q [x] (X = 1, 2, 3,..., M) for each of the m types of applications, one unit time t from these q [x] [1] is determined, and t [y] = yt [1] t [y] (y = 1, up to the maximum value qmax of q [x])
2,3, ..., qmax / t [1]), and for each t [y], q
max / t [1] buffers are created, and the transmission data for the wireless terminal newly input to the buffer is buffered based on the permissible dwell time, and the buffer with the smaller value of t [y] Extract and output in order.

According to a fifth aspect of the present invention, in the communication device of the fourth aspect, the transmission data for the wireless terminal newly input to the buffer has a permissible residence time q;
When there is a buffer containing data belonging to the same connection as the transmission data, and in the buffer having the largest value of t [y], kp ≦ (q
−t [y]) <(k + 1) p When there is a positive integer k, while changing k ′ in order from 0 to k−1, (t [y] +
Calculates the total value of the transmission data amount of the connection in the buffer having the value of the section of (k'-1) p, t [y] + k'p], and calculates the transmission rate at which the connection can be transmitted in the radio section in the period p. , A is obtained by subtracting the total value from the above, and a is a free space in a buffer having a value of t [y] + k'p, and t is the transmission data newly arrived within a and b. ] + K'p, and (b) when there is no buffer containing data belonging to the same connection as the transmission data, and (k + 1) p≤q <(k + 2) When there is a positive integer k of p, while changing k ′ in order from 1 to k, let a be the transmission rate at which the connection can be transmitted in the radio section in the period p, and let b be the free capacity of the buffer having the value of k′p. And a and In a range that does not exceed the b,
The newly arrived transmission data is input to the buffer having the value of k'p. For example, transmission data for a wireless terminal newly input to the buffer has an allowable residence time q,
If there is a buffer containing data belonging to the same connection as the transmission data, in the buffer having the largest value of t [y], kp ≦ (q−t)
[y]) When there exists a positive integer k such that <(k + 1) p,
While changing k ′ in order from 0 to k−1, (t [y] +
Calculates the total value of the transmission data amount of the connection in the buffer having the value of the section of (k'-1) p, t [y] + k'p], and calculates the transmission rate at which the connection can be transmitted in the radio section in the period p. , A is obtained by subtracting the total value from the above, and a is a free space in a buffer having a value of t [y] + k'p, and t is the transmission data newly arrived within a and b. + K'p is input to a buffer having a value of p. If k 'is k in this procedure and the transmission data cannot be accommodated as a result, the remaining buffer has a value of q. If all newly arrived transmission data is input to the buffer on the way, the processing is terminated at that point in time, and if there is no buffer containing data belonging to the same connection as the transmission data, (K + 1) When there is a positive integer k satisfying ≦ q <(k + 2) p, while changing k ′ in order from 1 to k, the transmission rate at which the connection can be transmitted in the wireless section in the cycle p is a, and the connection has a value of k′p. Assuming that the free space in the buffer is b and the newly arrived transmission data is input to a buffer having a value of k′p within a range not exceeding a and b, and as a result of completing the procedure where k ′ is k, If all of the transmission data cannot be accommodated, all the remaining data is input to a buffer having a value of q,
If all the newly arrived transmission data is input to the buffer on the way, the process of writing the transmission data to the buffer is performed such that the processing is terminated at that point.

A communication device according to a sixth aspect of the present invention is the communication device according to the fourth aspect, wherein the buffer unit having a longer permissible time period than the period at which the transmission data arrives from the wireless terminal calculates the permissible permissible time period of the buffer. A means for cyclically changing each cycle by the cycle. For example, the value of t [y] of the buffer is updated every cycle t [1], the value of the buffer of value t [1] is qmax, and the other values of t [y] are tmax.
It has a timer management of the buffer that the value of [y] is replaced by t [y-1].

A communication device according to a seventh aspect of the present invention is the communication device according to the fourth aspect, wherein the free space of the buffer is calculated based on the amount of data currently stored in the buffer from the permissible time of the buffer. It is a value obtained by subtracting the amount of data currently stored in the buffer having the shorter allowable residence time. For example, the buffer having the value of t [1] has, as a free buffer capacity, a value obtained by subtracting the amount of data currently stored in the buffer from the amount of data that can be transmitted during the period t [1]. The above t [y] (y = 2,3,..., Qmax / t
The buffer having the value of [1]) is already stored in the buffer having the value of t [z] (z = 1,..., Y), respectively, based on the amount of data that can be transmitted during the period t [y]. The buffer capacity management is performed such that a value obtained by subtracting the total amount of data stored is used as a free buffer capacity.

The communication device according to the present invention is characterized in that the allowable time for transmission data transmission from a wireless terminal for a new call is longer than the period of exchange of a wireless frame with the wireless terminal, If the sum of the line output rates of the new calls is equal to or less than the output line rate, the call is accepted, and if it is above, the call is rejected. If the period is smaller than the exchange period of the radio frame between the existing connections, the total line output rate of the new call and all the connections of the existing connection whose allowable retention time is equal to or less than the allowable retention time of the transmission data from the wireless terminal is calculated. If the amount of data to be output within the permissible residence time at that rate is less than the amount of data that can be actually output to the line within that time, the call is accepted. Give performs refuse call reception control call when the above. For example, at least one is a system in which a wireless terminal performs communication using an ATM adaptation layer type 2, and a transmission and an arrival period of a wireless frame, which is a unit of data transmission between the wireless terminal and the wireless base station, are set. For each of the p and m types of applications, let q [x] (X = 1, 2, 3,..., m) denote the permissible residence time of transmission data from the radio terminal at the radio base station, and a new call arrives. Assuming that the permissible residence time of transmission data from the radio terminal at the radio base station is q, and q is equal to or greater than p,
The call is accepted when the sum of the line output rates of all m types of applications and new calls is equal to or less than the output line rate, and rejected if the sum is greater than the line rate, while q is less than p. In this case, the total line output rate of the m types of applications, all of which have an allowable residence time of q or less, and a new call is calculated, and the amount of data to be output during the period of q at that rate is actually the same during the same period. If the data amount is smaller than the data amount that can be output to the ATM line, the call is accepted; otherwise, the call is rejected.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration of a communication system according to an embodiment of the present invention. As shown in the figure, a wireless terminal 1 moves and communicates with a nearby wireless base station 2, while a plurality of wireless base stations 2 are connected to an exchange 3 and an ATM line 4. AT after switch 3
Various public or private networks such as M network, N-ISDN, PSTN are connected.

In general, in the wireless section 7, transmission data is transmitted in a fixed-length frame called a wireless frame.
As shown in these figures, these radio frames 5
, And a plurality of radio frames 5 arrive almost simultaneously. For example, in the CDMA technology, since the difference in data is recognized by the difference in code using the same frequency, wireless frames from different wireless terminals 1 are almost synchronized due to the necessity of synchronization between codes. Therefore, as a characteristic of the data that arrives, a radio frame whose maximum amount is determined in a burst manner arrives from the radio terminal 1 to the radio base station 2 at regular intervals.

As shown in FIG. 3, a radio frame 6 similarly transmitted from the radio base station 2 to each radio terminal 1 is transmitted at the same cycle as the arriving radio frame 5. Therefore, the transmission data also comes out in a burst at regular intervals. The transmission and reception cycle of the radio frames 5 and 6 is
For example, in wideband CDMA, it takes about 10 ms,
In this case, even with traffic of 64 kbps, the data amount accommodated in one frame is 640 bits.

Generally, applications, such as data,
The maximum value of the permissible delay is determined depending on audio, video, and the like, and can be assigned to each component shown in FIG. Specifically, the wireless terminal 1 has a delay until data transmission, a delay in the wireless section 7, a reception delay in the wireless base station 2, a delay for transmission from the wireless base station 2 to the exchange 3, an exchange 3 , A delay for transmission from the exchange 3 to the wireless base station 2, a processing delay for the wireless base station 2 to receive from the exchange 3, and a delay for transmission from the wireless base station 2 to the wireless terminal 1. , The delay in the wireless section 7, the reception delay of the wireless terminal 1, and so on.

Here, as a first embodiment, control of a delay when the radio base station 2 transmits data to the exchange 3 will be described. As a second embodiment, the exchange 3 will transmit data to the radio base station 2. Control of delay at the time of transmission will be described, and as a third embodiment, call admission control as a premise to enable such delay control will be described.

(First Embodiment) FIG. 4 is a diagram showing a configuration of the radio base station 2. As shown in FIG. As shown in FIG.
A receiving unit 8 for reproducing a signal received from a wireless section 7 via an antenna, a packetizing unit 9 for assembling a reproduced signal (wireless frame) into a packet of a predetermined format, and temporarily storing the assembled packet; Buffer unit 10 for loading ATM cells, ATM output from buffer unit 10
It has an ATM interface unit 11 for transmitting cells to the ATM line 4.

FIG. 5 is a diagram showing the operation of the packetizing section 9.

As shown in FIG. 1, a plurality of radio frames 5 transmitted from the radio terminal 1
Will be fixed. One wireless terminal 1 has a plurality of wireless frames 5
, One information packet 12 is completed by combining those radio frames 5. That is, the information packet can have a variable length.

This information packet 12 is packetized into an AAL type 2 packet 13. Regarding packetization, AAL type 2 first SSCS (Service
Specific Convergence Subl
ayer) if necessary with sequence number (SN) and C
Attach RC. And CPS (Common Par)
At t Sublayer), it is divided into 45 octets and a header H of 3 octets is added.
A header H of 3 octets is similarly created for the fraction.

Here, the buffer section 10 has a plurality of buffers 10a, 10b, 10c,... Having different capacities. The packets 13 of the CPS are stored in the buffers 10a, 10b,... According to the respective delay characteristics. The buffers 10a, 10b,... Are logically separated in FIG. 5, but may be physically shared memory.
Input / output is performed in each of the buffers 10a, 10b,... According to a FIFO rule. Then, the buffers 10a, 10
b,... according to the transmission priority from
Data is read from 0b,..., Mapped to ATM cells, and sent to the ATM interface unit 11.

There is a problem of where to define the allowable stay time of each transmission data. The end is buffer 10a,
It can be said that the transmission data is read from 10b,... And mapped to ATM cells. On the other hand, the start time of the residence time is, for example, a method of starting when each radio frame is received at a certain period and forming an information packet from the frame, a method starting when forming an AAL packet, Also, there is a method of starting when the first AAL packet is put into the buffers 10a, 10b,. In this example, AAL type 2 CPS
The packetization is completed, and the first packet is stored in the buffer 10.
a, 10b,... is a start time.
In other words, it can be realized with little change in other cases.

The operation of input to buffers 10a, 10b,... And output from buffers 10a, 10b,.

Assuming several applications in the long term, for each application,
It is necessary to define the allowable residence time described above. For example, application A is q [1], application B
Is determined as q [2], and so on. Assuming that there are m types of applications, there are m types of q [x] including those having the same value.

As a policy of output, it is necessary to put out a queue having a short permissible residence time first, so that the queue is put in a separate queue for each q [x], and the output is started from a queue having a small value of q [x]. Will do. For this reason, the buffers 10a, 10
.. are marked, and the arriving data is input to the buffers 10a, 10b,... having the corresponding marks, and the transmission order between the buffers is controlled by comparing the marks of the buffers 10a, 10b,. Is used.

Regarding the way of marking, it is easiest to match it with the value of the allowable residence time, so that it will be used. That is, the arriving transmission data is stored in the buffers 10a, 1a in which the permissible residence time q [x] is written.
0b,...

However, the value of q [x] often becomes much larger than the arrival period p of the radio frame. For example, as shown in FIG. 6, assuming that the allowable dwell time of transmission data A arriving at a certain time is 20 ms, and that the allowable dwell times of transmission data B and C arriving 10 ms later are 5 ms and 15 ms, respectively, Although the data B arrives later, it must be output to the ATM line first, and the transmission data C is transmitted data A even though the allowable residence time is shorter than the transmission data A.
The output is delayed.

In order to enable the flexibility of the transmission order with respect to the arrival order, each buffer 10
It is necessary to change the value of the allowable residence time described in a, 10b,. That is, at a certain time, the transmission data having the allowable residence time q [x] is written in each buffer 10a, 10b,. The value of the permissible residence time is reduced by a certain value.

In the case of the present embodiment, since new transmission data arrives only at every fixed period p, it is sufficient to update the allowable stay time every p.

FIG. 7 shows a specific example. Here, for the sake of simplicity, only two types of applications A and B are assumed, and it is assumed that application A has a residence time of 5 ms and B has an allowable residence time of 50 ms. The period p of the arrival of the radio frame is 1
It is assumed to be 0 ms.

It is assumed that transmission data A1 of application A and transmission data B1 of application B arrive at a certain time. 5 ms because the permissible residence time of A1 is 5 ms
Is input to the buffer 701 having the display Meanwhile B
Since the stay allowable time of 1 is 50 ms, it is input to the buffer 702 having a display of 50 ms.

It is assumed that the transmission data A2 of the application A and the transmission data B2 of the application B arrive when the period p, that is, 10 ms has elapsed. Since the allowable residence time of A1 is shorter than the period p, A1 has already been output to the ATM line. As a result, the buffer 701 is empty and has a display of 5 ms.
2 is input to the buffer 701. On the other hand, the buffer 70
2 has the possibility that B1 may still remain, and since the permissible residence time is clearly shorter than that of B2 coming next,
For the sake of distinction, the display is changed to 40 ms, which is obtained by subtracting 10 ms from the display of a certain residence allowable time of 50 ms. Then, a buffer 703 having a display of the permissible residence time of 50 ms is prepared, and B
2 is entered there.

In the next cycle, the transmission data A3 of the application A and the transmission data B3 of the application B
Has arrived. Since the buffer 701 is empty because A2 has already been output, the problem of order control does not occur. Therefore, A3 is input to the buffer 701. The value of the buffer 702 is rewritten from 40 ms to 30 ms, and the value of the buffer 703 is rewritten from 50 ms to 40 ms. Then, a buffer 70 having a new value of 50 ms
Prepare 4 and put B3 there.

As described above, in addition to the buffer 701 having a value of 5 ms, 10 ms, 20 ms, 30 ms
It can be seen that buffers having respective values of ms, 40 ms and 50 ms are required. The 10ms buffer is
In the next cycle, the contents will definitely be empty, so 50m again
If it is rewritten as s, it can be reused.

Therefore, in this example, as shown in FIG.
Buffer 701 having a value of 5 ms, maximum value being 50 ms, 50 ms → 40 ms → 30 ms → 20 ms → 10 ms →
50 ms and its value changes cyclically, and at the same timing, the five types of buffers 7 whose values are different from each other.
It can be seen that six types of buffers from 02 to 706 are required.

When the above is generalized, the arrival period of the wireless frame 5 which is a unit of data transmission from the wireless terminal 1 is p,
The permissible residence time of transmission data from the radio terminal 1 in the radio base station 2 is defined as q [x] (X
= 1,2,3, ..., m), q [x] for each q [x]
And t [y] (y from the smallest one of all positive values obtained by subtracting p one or more times from q [x], excluding duplicates
= 1, 2, 3,..., N), and creates n buffers each having t [y] as the value of the allowable stay time.

The transmission data from the wireless terminal 1 is put into a buffer 10 having the same value of t [y] as the allowable staying value, and t
Data is sent to the network side in order from the buffer 10 having the smallest value of [y].

The value of t [y] in the buffer 10 is updated every period p during which data from the next wireless terminal 1 arrives.

Buffer 1 having a value of t [y] larger than p
0 is replaced by the value of t [y] -p, and t [y] less than or equal to p
The buffer 10 having the value of t [y] and the value obtained by adding p to the t [y] one or more times has the same value as the residence allowable value of the application, and of the maximum t [y] among them. Is replaced by the value.

The data transmission is performed by changing the buffer 10 having the replaced value from the smallest value to t [1], t [2],.
Buffer 10 with the value of t [1]
Are output to the ATM line 4 in order from the contents.

Next, the required buffer capacity based on the output line capacity will be described.

The ATM line 4 generally uses 155 Mbps or the like. However, when the AAL type 2 is used, a relatively narrow band, for example, a line of 6 Mbps or 1.5 Mbps is often used. Here, it is assumed that 1.5 Mbps is used.

A 1.5 Mbps line is exactly 1.53
6 Mbps, and one 125 μs frame has 1
93 bits are included. One of the bits is an F bit, so that the ATM cell can accommodate 192 bits (24 octets).

As an example, as shown in FIG.
Assuming that there are only two buffers of ms and 10 ms, 960 octets are available at 40 times 24 octets at 5 ms. An ATM cell is included in the ATM cell. The ATM cell has 5 octets out of 53 octets as a header, and 1 octet of the payload is used to accommodate an AAL type 2 CPS packet. About Octet 47
Each octet can be used. Then, in 960 octets, 53 octets are 18 and the remainder is 6 octets, so the number of octets that can be used in 5 ms is 846 octets or more and 852 octets or less. Here, as a fixed value, 846 octets are given to a buffer having a value of 5 ms, assuming that 846 octets are a band usable by the user. That is, as shown in FIG. 9A, the buffer 901 having a value of 5 ms
Assuming that up to 6 octets are available and 500 octets are currently in its buffer, 846-50
At 0, 346 octets are free space.

On the other hand, in the case of 10 ms, the free area changes depending on the state of 5 ms. At 10 ms, 1920 octets can be used, and considering the overhead due to the same ATM cell as before, the capacity of the buffer 902 having a value of 10 ms is 1 as shown in FIG.
698 octets. However, assuming that 700 octets are used in the buffer 902 as the free space, it is assumed that 700 octets from 1698 octets to 500 octets are used in the buffer 901 having a value of 5 ms.
By subtracting both octets, 498 octets become free space. As described above, the size determined to be a free area is affected by the presence or absence of a buffer having a stay allowable time smaller than the stay allowable time of the buffer.

When this is generalized, the value of the allowable residence time attached to the buffer is changed from the smaller one to t [1], t [2],
…, T [n], the buffer having the value of t [1] is
It has a value obtained by subtracting the amount of data currently stored in the buffer from the amount of data that can be transmitted during the period t [1], and has a value of t [y] (y = 2 to n). The buffer calculates t [z] from the amount of data that can be transmitted during the period t [y].
The value obtained by subtracting the total amount of data stored in the buffer having the value of (z = 1, 2, 3,..., Y) has the free buffer capacity.

(Second Embodiment) FIG. 10 is a diagram showing the configuration of the exchange 3. As shown in FIG. 1, the exchange 3 includes a switch 14 for exchange, a packetizing unit 15 for assembling transmission data distributed by the switch 14 into a packet of a predetermined format, temporarily storing the assembled packet, and
It has a buffer section 16 for loading M cells, and an ATM interface section 17 for sending out ATM cells output from the buffer section 16 to the ATM line 4.

FIG. 11 is a diagram showing the operation of the packetizing section 15.

Here, unlike the first embodiment, the data transmitted from the network arrives irregularly. Therefore, as shown in FIG. 11, the information packet output from the switch unit 14 is
The data is stored in an IFO buffer 18 and sequentially extracted therefrom.

The extracted information packet 19 is converted into an AAL type 2 CPS by the same procedure as in the first embodiment.
Packet 20 is formed.

Here, the buffer section 16 has a plurality of buffers 16a, 16b, 16c,... Having different capacities. Then, the CPS packets 20 are stored in the buffers 16a, 16b,... According to the respective delay characteristics. At this time,
The difference from the first embodiment is that the AAL type 2 packet 20 generated from the same information packet may be put in different buffers 16a, 16b,. In the following, the principle here and the buffers 16a, 16a
The values of b,... will be described.

In the second embodiment, the arrival of the information packet 19 can be considered at all timings. Therefore, each time each information packet 19 arrives, the buffers 16a, 16a
The buffering must be performed while changing the value of the stay allowable time assigned to b,... in principle. It is impossible to update every cycle p as in the first embodiment. However, since it is difficult to perform it strictly in terms of mounting, it is performed in a form that allows some rounding error.

The permissible dwell time at the interface from the exchange indicated by the application to the radio base station is defined as q [x] (X = 1, 2,
3, ..., m), a unit t [1] is determined from this value. The best way to determine t [1] is to take the greatest common divisor of m q [x].
If it is ms, it is desirable for calculation to be a divisor. That is, in general, it is settled at a place such as 1 ms or 2 ms. Here, it is assumed that t [1] is 1 ms.

Each buffer needs to change its value every time t [1]. Therefore, the largest of q [x] is qma
Assuming x, all buffers up to qmax that are multiples of t [1] are needed. Therefore, the number of buffers is qmax /
t [1].

Each buffer changes from t [y] to t [y-1] every time t [1]. Here, t [y] corresponds to y * t [1]. However, since the contents of the buffer having the value of t [1] become empty, it is changed to qmax. That is, as shown in FIG. 12, the maximum value is qmax, and its value cyclically changes by t [1] every t [1], and at the same timing, the values are different from each other qmax / t [1]. It turns out that the number of buffers is required.

Next, the required buffer capacity based on the output line capacity will be described. ATM line is 155Mbps
However, when using AAL type 2, a relatively narrow band, for example, a line of 6 Mbps or 1.5 Mbps is often used. Here, it is assumed that 1.5 Mbps is used.

A 1.5 Mbps line is exactly 1.53
6 Mbps, and one 125 μs frame has 1
93 bits are included. One of the bits is an F bit, so that the ATM cell can accommodate 192 bits (24 octets).

Assuming now that there are only two buffers having an allowable residence time of 1 ms and 2 ms, 192 octets can be used in 8 ms of 24 octets in 1 ms. An ATM cell is included in the ATM cell. The ATM cell has 5 octets out of 53 octets as a header, and 1 octet of the payload is used to accommodate an AAL type 2 CPS packet. Each octet can be used for 47 octets. Then, in 192 octets, 53 octets are 3 and the remainder is 33 octets, so the number of octets that can be used in 1 ms is 168 octets or more and 17
It is less than 4 octets. Here, as a constant value, 16
Assuming that 8 octets are the band that the user can use,
A buffer having a value of 1 ms is given 168 octets. That is, as shown in FIG. 13A, a buffer 1301 having a value of 1 ms can always be used up to 174 octets, and if 100 octets are currently stored in the buffer, 74 octets are available in 174-100. Becomes

On the other hand, in the case of 2 ms, the free area changes depending on the state of 1 ms. In 2 ms, 384 octets can be used. In consideration of the overhead due to the same ATM cell as before, the capacity of the buffer having a value of 2 ms is 336 octets at the maximum. However, FIG.
As shown in (b), assuming that 200 octets are used in the buffer 1302, the free capacity of the buffer 1302 is 20 to 336 octets.
By subtracting both 0 octets and 100 octets used in the 1 ms value buffer, 36 octets are free space. As described above, the size determined to be a free area is affected by the presence or absence of a buffer having a stay allowable time smaller than the stay allowable time of the buffer.

When this is generalized, the value of the allowable residence time attached to the buffer is changed from the smaller one to t [1], t [2],
…, T [n], the buffer having the value of t [1] is
It has a value obtained by subtracting the amount of data currently stored in the buffer from the amount of data that can be transmitted during the period t [1], and has a value of t [y] (y = 2 to n). The buffer calculates t [z] from the amount of data that can be transmitted during the period t [y].
The value obtained by subtracting the total amount of data stored in the buffer having the value of (z = 1, 2, 3,..., Y) has the free buffer capacity.

As described above, since the information packet input in FIG. 11 is passing through a network such as a public network, the delay fluctuates. In addition, a large information packet may be output from a wired terminal regardless of the structure of the wireless frame of the wireless terminal 1.

If no countermeasures are taken with respect to these fluctuations and the size of the information packet, an excessive amount of buffer will be stored in the radio base station 2 on the receiving side. In the wireless base station 2, the wireless terminal 1
However, since it has a characteristic that communication is performed through the wireless section 7 where the maximum value is determined every fixed period p, burst traffic in the wired section cannot be absorbed. On the other hand, causing such stagnation means that there is transmission data that cannot be transmitted, and the unbalanced state eventually leads to a decrease in the throughput of the entire system. Maybe.

Therefore, on the output side of the exchange 3, it is necessary to consider a queuing method for the buffer to reduce the burstiness of the transmission data to be transmitted to the radio base station 2. However, there is a premise that the permissible residence time in this part must be observed.

The principle is as shown in FIG.

That is, when the transmission data of a certain connection arrives (step 1401), it is checked whether or not the allowable stay time q is longer than the period p (step 1).
402). If q is equal to or smaller than p, the value is directly stored in a buffer having q as a value (step 1403). If q is larger than p, the buffer in which the connection is last queued is searched (step 1404).

When there is such a buffer, and the difference between the value of the allowable residence time q 'of the buffer and the value of the allowable residence time q of the transmission data is less than p (step 140).
5) All transmission data that has arrived this time is unconditionally put into a buffer having a value of q (step 1403).

If the difference between the value of q ′ and q is equal to or larger than p, the transmission data of the connection queued in the buffer having the value of the section of (q′−p, q ′) The sum s of the quantities is obtained (step 1406).
Then, the value a obtained by subtracting the total amount from the amount of transmission data passing through the wireless section during the period p is compared with the minimum value of the free space in the buffer, and the smaller value is set to b (step 1407). ). Next, within the range not exceeding b
The arriving transmission data is sequentially input to the buffer for each CPS packet (step 1408). However, (numerical 1, numeric 2) means that it is larger than numeric 1 and less than or equal to numeric 2.

Next, the difference between the value of q 'and q is k * p (k>
1) If it is equal to or greater than (step 1409), the received transmission data is divided into CPS packets for each CPS packet within the range not exceeding the empty area in the buffer having the value of q '+ (k-1) p in ascending order of k. The data is sequentially input to the buffer (step 1410).

If the input of the arrived transmission data has been completed in the process of inputting to these buffers (step 1411), the operation is terminated at that point, and conversely, the input to these buffers is performed. If there is any remaining transmission data that has arrived as a result of the attempt, they are all input to a buffer having a value of q (step 1403).

On the other hand, when there is no buffer in which the connection is queued (step 1404), and when q is equal to or less than p (step 1412), all transmission data arrived this time unconditionally have the value of q. It is put in the buffer (step 1403).

If the value of q is equal to or larger than k * p (k> 1) (step 1413), the value of q exceeds the free space in the buffer having the value of (k-1) p in ascending order of k. Within this range, the transmission data that has arrived is sequentially input to the buffer for each CPS packet (step 141).
4).

Then, if the input of all of the arriving transmission data is completed in the process of inputting to those buffers (step 1411), this operation is completed at that time, and conversely, the input to these buffers is completed. If there is any remaining transmission data that has arrived as a result of the attempt, they are all input to a buffer having a value of q (step 1403).

In such an input method to the buffer, a certain type of shaping is performed so that the transmission capacity in the wireless section does not exceed the period p when viewed in a certain section. Furthermore, queuing is performed as fairly as possible within that range, and transmission data that arrives late can be input to a buffer that is output earlier.

By doing so, it is possible to suppress an increase in the buffer in the radio base station due to the inability to output in the radio section. In addition, the transmission efficiency can be increased by minimizing the transmission of an empty wireless section in a vacant state when the vehicle arrives late. Furthermore, by enabling the wireless section to be used effectively, abnormal stagnation of each connection is eliminated, and it is possible to suppress delay and packet discard.

(Third Embodiment) As a third embodiment, a call admission control for successfully performing the delay control in the first embodiment and the second embodiment will be described.

In the case of the ATM network, the call admission control is originally performed according to Q.25. It is common to use a signaling protocol such as 2931. However, A
In AL type 2, not one VC level but one V
Since it is necessary to take into account the case where a plurality of users are multiplexed on C, a method called ANP is used based on the existing signaling method. However, since ANP corresponds to signaling at the AAL level, a simple procedure is desirable. Here, a relatively simple procedure is described.

In the first and second embodiments, the case where data overflows from the buffer is described.
I did not specifically state. When the buffer overflows, the transmission data is discarded, but it is important to devise a method of accepting the call so as to avoid the transmission data as much as possible.

Therefore, the case of the first embodiment will be verified first. As an example, the arrival period p of the radio frame is 10 ms,
It is assumed that the stay allowable time is 30 ms for the application A, 20 ms for the application B, and 10 ms for the application C. When the transmission data of the applications A, B, and C arrive at a certain time, 30
At first glance, they appear to be irrelevant since they are input to different buffers with dwell delay values of ms, 20 ms and 10 ms.

However, it is assumed that the transmission data of the applications A, B, and C arrives in the next cycle. The transmission data of the application B is written into a buffer having an allowable residence time of 20 ms, and the transmission data of the application A that has arrived last time is stored in this buffer. This is because the buffer having the allowable residence time of 30 ms at the previous time has a value corresponding to the period, that is, a value of 20 ms obtained by subtracting 10 ms since one cycle has elapsed.

Similarly, in the next cycle, 10 m
The transmission data of the application C that has arrived this time and the application B that has arrived last time are stored in the buffer having the value of s.
Transmission data and application A that arrived just before
Is transmitted. Unless the state of the buffer immediately before the transmission is taken into consideration, it is not known whether or not the buffer overflows.

As another discussion, the free space of each buffer is variable depending on how much transmission data is buffered in a buffer having a smaller allowable residence time than the buffer. Specifically, as described above, the free space of the buffer having the value of t [1] is t
[1] The amount of data that can be sent during the period minus the amount of data currently buffered. The free space of the buffer having the value of t [y] (y = 2, 3,..., n) is t
From the amount of data that can be transmitted during the [y] period, the current t [z] (z = 1,
2,3, ..., y-1) minus the total amount of data in the buffer. Therefore, not only those in the same buffer but also the free space of a buffer having a smaller permissible dwell time than that buffer must be considered.

Based on these facts, when a new call arrives, a method of determining the acceptance of the call will be considered.

Now, the existing connections are as follows: Connection A, B, C Transmission data amount in one frame is 80 octets Permissible retention time is 5 ms Connection D, E Transmission data amount in one frame is 180 octets The permissible time is 5 ms. The transmission data amount in one frame of connection F is 180 octets. The permissible retention time is 25 ms. The transmission data amount in one connection G frame is 480 octets. The permissible retention time is 50 ms.

As described above, in the call admission control, the determination must be made using a buffer shorter than the period p.
This is because a buffer having a value of 20 ms has the largest buffer capacity when it is rewritten to a value of 10 ms, and it means that there is no buffer overflow at that time. If the period p is 10 ms for the above example, the first
As shown in the embodiment, there are two buffers having values of 5 ms and 10 ms. Therefore, a buffer having these two values is assumed for call admission control. When a new call is received, a call is accepted when these buffers do not overflow, and rejected when the buffers overflow.

As described above, assuming a 1.5 Mbps line, the maximum size of a buffer having a value of 5 ms is 846 octets. In a buffer having a value of 10 ms, the maximum is 1698 octets.

Now, it is assumed that the transmission data of the above connection is stored in these buffers. A to E
Up to 5 ms are counted in a buffer having a value of 5 ms. On the other hand, since F and G are values larger than the period p, that is, 10 ms, they are all counted in the buffer having a value of 10 ms. As in the first embodiment,
The application F is actually input to a buffer having a value of 25 ms, and the value is rewritten to 5 ms after two cycles, so that the allowable residence time enters the buffer of 5 ms. However, this is different from the count in the call admission control. . This is shown in FIG.

The AAL type 2 adds a 3-octet header every 45 octets. Application A,
For B and C, the transmission data is 80 octets, but a header for 6 octets is added, and the data becomes 86 octets in the buffer. The applications D and E each have 192 octets with an overhead of 12 octets. As a result, the buffer having a value of 5 ms is 84
By subtracting the number of octets of the AAL2 packet of each application from 6 octets, a free area of 204 octets is obtained.

The application F has 192 octets with a 12-octet CPS header like D and E, and the application G has 11 CPS packets. As a result, in a buffer having a value of 10 ms, the number of octets of all the CPS packets of the applications A, B, C, D, E, F, and G is subtracted from 1698 octets, and a free area of 351 octets is obtained.

Thus, the following call acceptance determination is performed.

(1) When the call has an allowable residence time of 5 ms In this case, the call is accepted if the transmission data of one radio frame is 204 octets or less, which is the free space of the buffer having a value of 5 ms, and rejected if the transmission data is larger than that. Will do.

(2) When the Permitted Stay Time is 10 ms or More The call is accepted if the transmission data of one radio frame is 351 octets or less, which is the free space of the buffer having a value of 10 ms, and rejected if the transmission data is larger than 351 octets. I do.

[0096] Here, it is assumed that a call having a permissible residence time of 25 ms and a transmission data of one radio frame having a length of 300 octets is originated. As described above, this call actually enters the buffer having a value of 5 ms, and from that point of view, the buffer of 5 ms has room for only 204 octets, and thus the call is rejected. However, since this call has a dwell time of 25 ms, it is perfectly acceptable to change this to 20 ms on the network side, for example. Then 10m in 20ms
Since the data is stored in the buffer having the value of s, in this case, there is a room of 351 octets, so that the data is accepted.

Thus, regardless of the buffering problem in the first embodiment, if a call having a dwell time exceeding 10 ms enters the 10 ms buffer and the call admission judgment is made, more calls can be obtained. It turns out that it can be accepted. According to the first embodiment when received in this manner, 5 m in each cycle
Since there is still room after outputting all data from the buffer having the value of s and the buffer having the value of 10 ms, 1
Data of a maximum of 351 octets can be read from a buffer having a value of 5 ms. Thus, by reading out the buffer having the value exceeding the period p first, the buffer having the value of 15 ms becomes 5 m in the next period.
5m remaining when changed to buffer with s value
This means that the data can be output during s.

The result is generalized as follows.

The period of transmission and arrival of a radio frame, which is a unit of data transmission between the radio terminal and the radio base station, is p, and m types of applications are allowed to stay at the radio base station for transmission data from the radio terminal for each of the m types of applications. Let the time be q [x] (X = 1, 2, 3,..., M), and let the new call arrive and the permissible retention time of the transmission data from the wireless terminal at the wireless base station be q.

If q is equal to or larger than p, the call is accepted when the sum of the line output rates of all m types of applications and new calls is equal to or less than the output line rate.
If it is higher than the line rate, it rejects the call.

On the other hand, if q is smaller than p, the total line output rate of the m types of applications, all of which have an allowable residence time less than or equal to q, and a new call is obtained, and the output during the period of q at that rate is obtained. If the desired data amount is equal to or less than the data amount that can be actually output to the ATM line during the same period, the call is accepted, and if not, the call is rejected.

By such call admission control, buffering can be performed in the radio base station without worrying about buffer overflow. Since this method is relatively simple, it can be sufficiently used as an ANP method.

Also, in the case of going from the exchange to the radio base station as in the second embodiment, as long as the call admission control is performed by the above-described method, no buffer overflow occurs unless there is a variation in delay. In addition, traffic with a large delay is devised so that it can be transmitted after being smoothed in each cycle by the method as in the second embodiment, so that the probability of buffer overflow can be sufficiently suppressed.

However, this does not hold when the traffic from the exchange to the radio base station is larger than the traffic in the opposite direction, such as broadcast traffic or asymmetric traffic. In the case where such an asymmetric connection is included, the problem is solved by using the larger transmission band as a parameter for the above-described call admission control.

[0105]

As described above, according to the first to third aspects of the present invention, an appropriate value of the allowable dwell time for traffic arriving in bursts at regular intervals in the form of a radio frame. Prepare a buffer having the following parameters, buffer each transmission data according to the parameter of the permissible dwell time, appropriately replace the permissible dwell time of the buffer at regular intervals, and then transfer the buffer with the shorter permissible dwell time to the exchange in order. By outputting the data to the ATM, priority control of the ATM type 2 in consideration of the delay time can be performed for each application.

Further, in the present invention as set forth in claims 4 to 7, fluctuations in traffic going to one wireless terminal within a range in which the dwell time in the exchange is maintained are taken into consideration by taking into account the characteristics of the wireless line as the last hop. By suppressing the transmission, relatively fair transmission control can be realized for each connection, and as a result, it is possible to suppress the dwell time in a portion from the radio base station to the radio terminal, and to reduce the buffer amount in the radio base station. it can.

Further, in the present invention according to the eighth aspect, the allowable admission time of the accepted connection in the radio base station is controlled by performing the call admission control so that the buffer overflow does not occur by utilizing the characteristics of the above invention. To the specified parameters, and
This is also valid for the second smoothed traffic,
It is possible to suppress an increase in the permissible residence time in the exchange.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a communication system according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a state of a wireless frame from a wireless terminal to a wireless base station.

FIG. 3 is a diagram illustrating a state of a wireless frame from a wireless base station to a wireless terminal.

FIG. 4 is a diagram illustrating a configuration of a wireless base station illustrated in FIG. 1;

FIG. 5 is a diagram illustrating an operation of the packetizing unit illustrated in FIG. 4;

FIG. 6 is a diagram showing a state of staying of transmission data in a buffer unit shown in FIG. 4;

FIG. 7 is a diagram showing an update of an allowable residence time in the buffer unit shown in FIG. 4;

FIG. 8 is a diagram showing an update of an allowable residence time in the buffer unit shown in FIG. 4;

FIG. 9 is a diagram for explaining a required buffer capacity based on an output line capacity;

FIG. 10 is a diagram showing a configuration of the exchange shown in FIG.

FIG. 11 is a diagram illustrating an operation of the packetizing unit illustrated in FIG. 10;

FIG. 12 is a diagram showing an update of an allowable residence time in the buffer unit shown in FIG. 10;

FIG. 13 is a diagram for explaining a required buffer capacity based on an output line capacity.

FIG. 14 is a flowchart illustrating a method of queuing in a buffer at the output side of the exchange to reduce the burstiness of transmission data transmitted to a radio base station.

FIG. 15 is a diagram for explaining buffer capacity calculation for call admission determination.

[Explanation of symbols]

 1 wireless terminal 2 wireless base station 3 exchange 4 ATM line 7 wireless section

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI H04Q 7/30

Claims (8)

[Claims] 1. storing transmission data from a wireless terminal;
A plurality of buffers having different residence time, means for accumulating the transmission data in the buffer having the residence time matching the residence time of the transmission data, and transmissions stored in order of the buffer having the smaller residence time. Means for sending data to the network side. 2. The communication device according to claim 1, wherein the permissible dwell time of the buffer having a permissible dwell time longer than a period at which the transmission data arrives from the wireless terminal is calculated for each period. A communication device, further comprising means for changing to a click. 3. The communication apparatus according to claim 1, wherein the free space of the buffer is calculated based on the amount of data currently stored in the buffer and the amount of time allowed for the buffer to be smaller than the allowable time for the buffer. A communication device, wherein the value is obtained by subtracting the amount of data currently stored in a buffer. 4. A plurality of buffers for accumulating transmission data from a network and having an allowable residence time of an integral multiple of a predetermined time unit, and said transmission data being stored in said buffer having an allowable residence time matching said residence time of said transmission data. And a means for transmitting the stored transmission data to the wireless terminal in order from the buffer having the shorter allowable residence time. 5. The communication device according to claim 4, wherein the transmission data for the radio terminal newly input to the buffer has an allowable residence time q, and (a) contains data belonging to the same connection as the transmission data. When there is a buffer and the buffer having the largest value of t [y] among the buffers, kp ≦ (q−t [y]) <(k +
1) When there is a positive integer k of p, while changing k ′ in order from 0 to k−1, (t [y] +
Calculates the total value of the transmission data amount of the connection in the buffer having the value of the section of (k'-1) p, t [y] + k'p], and calculates the transmission rate at which the connection can be transmitted in the radio section in the period p. , A is obtained by subtracting the total value from the above, and a is a free space in a buffer having a value of t [y] + k′p. B is t (y) within a range not exceeding a and b. ] + K′p, and (b) On the other hand, when there is no buffer containing data belonging to the same connection as the transmission data,
When there is a positive integer k such that (k + 1) p ≦ q <(k + 2) p, while changing k ′ in order from 1 to k, let a be a transmission rate at which the connection can be transmitted in a wireless section in a period p, and k′p A communication device characterized in that a free capacity in a buffer having a value of k is set to b, and newly arrived transmission data is input to a buffer having a value of k'p within a range not exceeding a and b. 6. The communication device according to claim 4, wherein the permissible dwell time of a buffer having a permissible dwell time longer than a period at which transmission data arrives from the wireless terminal is determined by the per-period period. A communication device, further comprising means for changing to a click. 7. The communication device according to claim 4, wherein the free space of the buffer is calculated based on an amount of data currently stored in the buffer and a remaining allowable time smaller than the allowable remaining time of the buffer. A communication device, wherein the value is obtained by subtracting the amount of data currently stored in a buffer. 8. The method according to claim 1, wherein the permissible time of transmission data from the radio terminal for a new call is longer than the cycle of exchange of radio frames with the radio terminal, and the line output rate of the existing connection and the new call is The call is accepted when the sum is equal to or less than the output line rate, and the call is rejected when the sum is equal to or greater than the line rate at which the transmission of data from the wireless terminal to the new call is allowed. If the period is smaller than the period, the total line output rate of the new call and all the connections in which the resident time of the existing connections is equal to or less than the resident time of the transmission data from the wireless terminal is determined. If the amount of data to be output within the time is equal to or less than the amount of data that can be actually output to the line within the time, the call is accepted. Communication apparatus and performing rejects the call admission control.