JP2003235073A - Data transmission system and method for utilizing communication frame - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a data transmission system capable of transmitting both data at a fixed data transmission rate used for an E1 interface or the like and data such as Ether frames produced at random by means of same wireless frames. <P>SOLUTION: A constant period slot assignment section 56 of a base station 11 assigns downlink data slots to packets supplied from a first communication interface circuit 157 at a fixed data transmission rate adopted for the E1 interface 6 or the like with preceding to realize the fixed data transmission rate and a request slot assignment signal processing apparatus 55 assigns the remaining downlink slots to packets related to Ether frames supplied via a second communication interface circuit 153 and a downlink subscriber station transmission buffer 65. Thus, the same base station 11 can transmit both the data at the fixed data transmission rate and the data caused at random by means of the same wireless frames. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bidirectional transmission between a single base station and a plurality of subscriber stations, for example, a time division multiplex (TDM) data transmission device and a time division multiple access. (Time division multi-ch
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission device suitable for application to an annel access (TDMA) data transmission device and a method of using a communication frame.

[0002]

2. Description of the Related Art Generally, a TDM / TDMA data transmission apparatus has a fixed period slot assigning unit for assigning use of a time slot to a corresponding subscriber station at a fixed period, and it is provided between a base station and each subscriber station. Has set a data channel of a predetermined fixed band.

In the case of transmitting a randomly generated data packet such as an Ethernet (registered trademark) frame (also referred to as an Ethernet frame), which has been increasing in recent years, such a fixed band data channel is called effective use of the band. Since it is inefficient from the point of view, the number of packets accumulated in the base station and each subscriber station is periodically measured, and the time slot is assigned based on the measurement result. , A plurality of subscriber stations share a band, and a band is efficiently used by utilizing a statistical multiplexing effect for bursty data traffic.

[0004]

Conventionally, a data transmission device that provides a fixed-band data channel and a data transmission device that transmits a randomly generated data packet such as an Ethernet (registered trademark) frame are different types. It is a device.

Therefore, when an attempt is made to transmit a randomly generated data packet such as an Ethernet (registered trademark) frame to a plurality of subscriber station devices by a fixed band data transmission device, it is necessary to send the data to each subscriber station device. If a band is set at the peak of bursty traffic, an enormous band will be required as a whole, and if the band of each subscriber station is set low, it will not be possible to cope with the instantaneous increase in traffic for each subscriber, and data transmission delay or Data loss occurs.

In either case, an unused band exists for a large amount of time, which is extremely inefficient from the viewpoint of effective use of the band.

On the other hand, the number of packets accumulated in the base station and each subscriber station is periodically measured, and a request-corresponding slot allocating section for allocating time slots based on the measurement result is provided. A data transmission device sharing a band can efficiently use the band by utilizing the statistical multiplexing effect on bursty data traffic.

However, when an attempt is made to transmit data of a fixed band, in other words, data of a fixed data transmission rate, with this type of data transmission device, a predetermined band may be set depending on the usage state of the band of another subscriber station. The problem that cannot be guaranteed arises.

The present invention has been made in consideration of the above problems, and it is possible to transmit both fixed data transmission rate data and randomly generated data in the same communication frame. The purpose is to provide a device.

It is another object of the present invention to provide a data transmission device and a method of using a communication frame, which enables efficient use of the communication frame.

[0011]

According to the data transmission apparatus of the present invention, a communication frame of a fixed length including a downlink data area divided into a plurality of time slots is repeated at a fixed period, and a plurality of data are transmitted from a single base station. In the data transmission device for transmitting a packet to a subscriber station in the time slot of the downlink data area, the base station divides data supplied from the outside at a fixed data transmission rate into packets. , A randomly generated data is supplied from the outside to divide the packet into a second data dividing unit and the packets output from the first and second data dividing units in a time slot of the downlink data area. When transmitting to the plurality of subscriber stations, the packet supplied from the first data division unit is preferentially set to the fixed data transmission rate. Assigned to the serial downlink data region, characterized in that it comprises a slot allocation unit that allocates the packets supplied the remaining downlink data area from said second data division unit (first aspect of the present invention).

According to the present invention, the slot allocation unit of the base station is supplied from the first data division unit when transmitting the packet to the plurality of subscriber stations in the time slot of the downlink data area in the communication frame. Packet is preferentially assigned to the downlink data area so that the fixed data transmission rate is achieved, and the rest of the downlink data area is assigned to the packet supplied from the second data division unit, so that the same base station transmits the fixed data transmission. Both speed data and randomly generated data can be transmitted to multiple subscriber stations without data loss. It is economical because both the data having a fixed data transmission rate and the data randomly generated can be transmitted in the same communication frame from the same base station.

Further, in the method of using a communication frame according to the present invention, a communication frame of a fixed length including a downlink data area divided into a plurality of time slots is repeated at a fixed cycle, and a plurality of subscriptions are made from a single base station. In a method of using the communication frame in a data transmission device for transmitting a packet to a central station in a time slot of the downlink data area, the base station divides data externally supplied at a fixed data transmission rate into packets. Data division process of
A second data division process in which randomly generated data is supplied from the outside and the base station divides the data into packets;
Packets divided in the first data division process when the packets divided in the first and second data division processes are transmitted to the plurality of subscriber stations in the time slots of the downlink data area. Is preferentially assigned to the downlink data area so as to have the fixed data transmission rate, and the rest of the downlink data area is assigned to the packets divided in the second data division step. (Invention of Claim 2).

According to the present invention, in the slot allocation process of the base station, when the packet is transmitted to the plurality of subscriber stations in the time slot of the downlink data area in the communication frame, the first
The packets divided in the data division process of are preferentially assigned to the downlink data area so that the fixed data transmission rate is obtained,
By using the communication frame to allocate the rest of the downlink data area to the packets divided in the second data division process, both fixed data transmission rate data and randomly generated data are transmitted from the same base station. Can be transmitted to a plurality of subscriber stations in the same communication frame without causing data loss. This makes it possible to transmit both data at a fixed data transmission rate and randomly generated data from the same base station, which is economical and enables efficient use of communication frames.

The data transmission apparatus of the present invention comprises an uplink for transmission from a plurality of subscriber stations to a single base station,
There is a communication frame of a certain length that is repeated in a certain period including a downlink that is transmitted from the single base station to the plurality of subscriber stations, and the plurality of subscribers are present in the uplink. A slot request area for requesting a time slot from a station to the single base station, and an uplink data area divided into a plurality of time slots for sending packets from the plurality of subscriber stations to the single base station. In the data transmission apparatus, wherein the downlink includes a slot allocation area for notifying the plurality of subscriber stations of the slot allocation in the base station, each subscriber station is externally provided at a fixed data transmission rate. First to divide the supplied data into packets
A data dividing unit, a second data dividing unit that is supplied with data that is randomly generated from the outside and divides the packet into packets, and a transmission buffer that temporarily stores the packets output from the second data dividing unit, Periodically measuring the number of packets accumulated in the transmission buffer, through the slot request area of the uplink, and a packet number measuring unit for requesting the base station allocation of time slots, the base station, When allocating the time slot of the uplink data area to each subscriber station, the data transmission rate of the packet transmitted to the base station through the first data division unit of the subscriber station is the fixed data transmission rate. And the remaining number of the upstream data area in response to the time slot allocation request from the packet number measuring unit. Characterized in that it comprises a slot allocation unit for allocating time slots (third aspect of the present invention).

According to the present invention, a time slot is preferentially assigned to a packet obtained by dividing data of a fixed data transmission rate, and a packet obtained by dividing randomly generated data is assigned to the remaining time slots. , Data at a fixed data transmission rate can be reliably transmitted at that data transmission rate, and randomly generated data can be efficiently transmitted, and since these can be transmitted in the same communication frame, the communication frame can be efficiently transmitted. Can be used for various purposes.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall configuration of a communication system 10 to which an embodiment of the present invention is applied.

This communication system 10 is a P-MP that provides a fixed wireless access service to a plurality of subscribers.
Used as a (point to multi-point) type.

The communication system 10 basically includes a base station 11 fixed to a building or a utility pole,
A plurality of subscriber stations 21 (1) to (3) (representatives) arranged in a company, a home, or the like, capable of bidirectional communication with the fixed base station 11 via wireless lines, respectively. Also referred to as a subscriber station 21).

In practice, the wireless link is comprised of the antenna 12 of the base station 11 and the antennas 22 (1) to 22 (1) of the plurality of subscriber stations 21.
(3) Established through wireless communication between (typically also referred to as antenna 22).

Each subscriber station 21 is a terminal 20 (1) to (3) such as a personal computer that inputs and outputs a frame in which data is randomly generated, such as an Ethernet (registered trademark) frame. , And E1 interfaces 2 (1) to (3) (typically also referred to as E1 interface 2) for inputting and outputting data at a fixed data transmission rate (fixed band) or ISDN.
Wired or wirelessly connected to (integrated services digital network) interfaces 4 (1) to (3) (typically also referred to as ISDN interface 4).

On the other hand, the base station 11 is mainly connected to the network 13 by wire and is also connected to the E1 interface 6 or the ISDN interface 8. It should be noted that the number of each of the E1 interface 6 and the ISDN interface 8 connected to the base station 11 is preferably equal to the total number of each of the E1 interface 2 and the ISDN interface 4 connected to the subscriber station 21. Keep it as a number. This is so that each can be used simultaneously as a dedicated line.

In this case, the terminal 20 of each subscriber station 21
It is possible to access the network 13 capable of transmitting randomly generated data via the wireless line and the base station 11.

As the network 13, IP (intern
et protocol) network or the like can be used. Further, as an interface for inputting / outputting data at a fixed data transmission rate, there are an E1 interface, an ISDN interface, a T1 interface and the like, and any of them can be used.

As is well known, the data transmission rate of the E1 interface 2 is fixed at 2.048 [Mbps], and the ISDN interface 4 is, for example, 64 [k].
bps] fixed.

For communication between the base station 11 and a plurality of subscriber stations 21, TDD (time division duplex) / TDMA is used.
(Time division multiple access) method can be used for bidirectional communication. In this case, a common radio frequency, for example, a 26 [GHz] band is allocated between the base station 11 and the plurality of subscriber stations 21, and efficient communication is possible due to the difference in the time slot used.

For communication between the base station 11 and a plurality of subscriber stations 21, an FDD (frequency division duplex) / TDM (to be described later) is used instead of the TDD / TDMA method.
The A method can be adopted. In addition, TDD / TDM
In either case of the A system or the FDD / TDMA system, the TDM (time division multip
lex) system and the upstream direction is TDMA system.

FIG. 2 shows a plurality of subscriber stations 21 and base stations 11.
2 shows a configuration of a wireless frame (one wireless frame) according to the TDD method for performing bidirectional communication with the wireless communication device. 1
The period of the wireless frame is about 1 to 10 [ms],
A fixed cycle, such as 2 [ms] in this embodiment, is selected. Of course, it is possible to select a shorter cycle or a longer cycle as the cycle of one radio frame in relation to hardware or the like. It should be noted that the frame of one radio frame having this fixed cycle is different from the frame such as the Ethernet frame having a variable length.

One radio frame has a downlink header area TS1.
1 and a downlink data area TS12, a DMF (delay measurement frame) area TS13, which is a time zone for measuring the propagation delay between the base station 11 and each subscriber station 21, a slot request area TS14, and an uplink. Uplink consisting of data area TS15 and guard time TS16
Composed of and.

The downlink header area TS11 is, as shown enlarged in FIG. 2, a preamble area TS17, a base station number area TS18, and a frame position designation area TS19.
And a command area TS20 including a control command such as DMF transmission permission, and a slot allocation area TS21.

In the case of a communication system in which data transmission of packets by time slots is performed only on the downlink, the uplink data area TS15 is included in one radio frame.
Becomes unnecessary. Further, in the case of a communication system in which packet data transmission by time slot is performed only on the uplink, the downlink data area is unnecessary in one radio frame.

FIG. 3 shows the downlink data area TS12 in FIG.
3 shows the detailed configuration of the. Downstream data area TS12
Is divided into a plurality of time slots, and each has a fixed downlink packet (also simply referred to as a packet).
Pd is assigned. Each downlink fixed length packet Pd is
Subscriber station number Pd1, channel number / recombining information Pd2 including channel number or adjacent packet presence / absence information, etc.
(This channel number / recombining information Pd2 includes only one of the channel number and the recombining information for each downlink fixed length packet Pd. Therefore, when the attribution is clear, the channel number Pd2 or Recombined information Pd2), fixed length data Pd3 that is actual data, and error detection code Pd4.

FIG. 4 shows the upstream data area TS15 in FIG.
3 shows the detailed configuration of the. Upstream data area TS15
Is divided into a plurality of time slots, and an upstream fixed length packet (simply referred to as a packet) P is provided for each.
u is assigned. Each upstream fixed length packet Pu includes
Guard time Pu1, preamble Pu2, subscriber station number Pu3, channel number / recombining information Pu4 including channel number or adjacent packet presence / absence information (also in this case, channel number Pu4 or recombining if attribution is clear) Information Pu4), fixed-length data Pu5 that is actual data, and error detection code Pu6.

The upper and lower data areas TS12, TS15
The configuration is common to the TDD / TDMA system and the FDD / TDMA system.

In this embodiment, the data length (data capacity) of the fixed length data Pd3 or fixed length data Pu5 constituting one downlink fixed length packet Pd and one upstream fixed length packet Pu is 128 [bytes]. ]. That is, 128 [bytes] of data can be transmitted in one time slot. 64 [bytes] instead of 128 [bytes]
Alternatively, it may be 256 [bytes] or the like.

FIG. 5 shows an example of 2-bit adjacent packet presence / absence information X {X = (a, b)} indicating the relation of the relevant packet with respect to the adjacent packet concerning the re-synthesis information Pd2. Recombining information Pd2 such as adjacent packet presence / absence information X
Is added when dividing variable length data randomly generated like an Ether frame into packets, and is used for recombining the Ether frames divided into packets.

Adjacent packet presence / absence information X {X = (a,
b)} is the first packet in the frame (for example, an Ethernet frame; hereinafter, in the description of the recombining information Pd2, the frame is called an Ethernet frame in order to avoid confusion with one radio frame). An information bit (also simply referred to as information) a (whether a = 1 is the beginning and a = 0 is not the beginning) indicating whether or not there is information, and information indicating whether or not the packet is the end packet in the Ethernet frame. Bit (simply referred to as information) b (b = 1 ends at
b = 0 and not the end. ).

In this case, adjacent packet presence / absence information X {X =
(A, b) = (1,1)} means that one complete Etherframe is contained in the packet. In other words, one Ethernet frame has a data length equal to or shorter than a fixed length packet. The adjacent packet presence / absence information X {X = (a, b) = (1,0)} means that the packet is the head packet of the Ethernet frame and there is a subsequent packet. The adjacent packet presence / absence information X {X = (a, b) = (0,0)} is
It means that the packet is an intermediate packet in which a succeeding packet is present following the preceding packet (also referred to as a preceding packet). Neighbor packet presence / absence information X {X
= (A, b) = (0,1)} means that the packet follows the previous packet and is the last packet of the frame. At this time, it is assumed that the packet order does not change in the transmission path.

The channel number / recombining information Pd2
In the present embodiment, the channel number is an E1 interface channel, an ISDN interface channel, or an identification code for identifying a plurality of these channels if they exist. E1
The interface and the ISDN interface are fixed band data channels, and the Ethernet frame is a data channel whose band changes (hereinafter, also referred to as variable band data channel).

FIG. 6 shows the configuration of each subscriber station 21 as an example. The subscriber station 21 basically includes an antenna 22, a high frequency circuit 32, and a communication control circuit 33.

The communication control circuit 33 is connected to the high frequency circuit 32 and also to the E1 interface 2, the ISDN interface 4 and the terminal 20.

The high frequency circuit 32 has a receiver 41, a transmitter 42, and a switch 43 with one circuit and two contacts arranged between the transceivers 41 and 42 and the antenna 22.

The transmitter 42 of the high frequency circuit 32 frequency-converts the intermediate frequency signal supplied from the communication control circuit 33 into a radio frequency signal by a built-in mixer, and also incorporates a radio frequency high frequency signal. The power is amplified by the power amplifier and supplied to the antenna 22 via the switch 43.

The receiver 41 of the high-frequency circuit 32 inputs the radio-frequency high-frequency signal received by the antenna 22 through the switch 43, amplifies it with the built-in low-noise amplifier, and then intermediates it with the built-in mixer. The frequency is converted into a frequency and supplied to the modulation / demodulation circuit 51 of the communication control circuit 33.

The communication control circuit 33 includes, in addition to the modulation / demodulation circuit 51, TDD-TDM / TDMA (simply, TDD / TDM).
It is called A. ) Control circuit 52, E1 interface 2 and I
It comprises a first communication interface circuit 57 connected to the SDN interface 4, a second communication interface circuit 53 connected to the terminal 20, a downlink reception buffer 61, an uplink transmission buffer 62, and a packet number measuring unit 63.

The packet number measuring unit 63 periodically measures the number of packets accumulated in the upstream transmission buffer 62 for each cycle of one radio frame, and uses this as information of the slot request (also referred to as the slot request number) 71. It is transmitted to the TDD / TDMA control circuit 52. The information of the slot request 71 is obtained from the TDD / TDMA control circuit 52 in the time zone of the slot request area TS14 of one radio frame of FIG. 2 in the modulation / demodulation circuit 51, the transmitter 42, the switch 43, and the antenna 22.
Is notified to the base station 11 through.

FIG. 7 shows the configuration of the base station 11 as an example. The base station 11 basically has an antenna 12
And a high frequency circuit 132 and a communication control circuit 34.

The structure and operation of the high frequency circuit 132 are the same as those of the high frequency circuit 32 of the subscriber station 21 shown in FIG.

The communication control circuit 34 includes a modulation / demodulation circuit 151,
TDD-TDM / TDMA (simply referred to as TDD / TDMA) control circuit 152, E1 interface 6 and IS
A first communication interface circuit 157 connected to the DN interface 8 and a second communication interface circuit 157 connected to the network 13.
Communication interface circuit 153, request slot allocation unit 5
5 and a fixed-cycle slot allocation unit 56, a slot allocation unit 54 for each upstream subscriber station, a transmission buffer 65 for each downstream subscriber station, and a packet number measurement unit 66.

The packet number measuring unit 66 includes the subscriber stations 21 (1) to 21 (1), which are accumulated in the transmission buffer 65 for each downlink subscriber station.
The number of packets for each (3) is periodically measured for each cycle of one radio frame, and this is transmitted to the required slot allocation unit 55 that constitutes the slot allocation unit 54. The TDD / TDMA control circuit 152 extracts the information of the slot request 71 of each subscriber station 21 notified in the time zone of the slot request area TS14 of one radio frame in FIG.
Communicate to.

The request slot allocating section 55 is used by the subscriber station 21.
On the basis of the number of packets (the number of stored packets) for each and the information of the slot request 71, regarding the allocation of the time slots configuring the upper and lower data areas TS12 and TS15 of the downlink and the uplink, how many times to which subscriber station 21 The so-called schedule calculation of which radio frame the slot is assigned to is performed, the information of the slot assignment 72 is determined, and the TDD / TDMA control circuit 152 is notified.

Further, the fixed-cycle slot allocator 56 allocates to which subscriber station 21 and how many subscriber stations 21 in a predetermined cycle with respect to allocation of time slots constituting the upper and lower data areas TS12 and TS15 of the downlink and the uplink. The information of the slot allocation 73, which radio frame the time slot is allocated to, is determined, and the TDD / TDMA control circuit 152
To notify.

The time slot allocation to the upstream data area TS15 in the upstream direction for each subscriber station 21 is as follows.
Slot allocation area TS21 in one radio frame in FIG.
Will be notified during the time zone.

In each of the upper and lower data areas TS12 and TS15 of one radio frame, the terminal 20 and the terminal 20 and the transfer data from the E1 interfaces 2 and 6 and the ISDN interfaces 4 and 8 are set so that the transfer data satisfy these data transmission rates. Priority is given to transfer data from the network 13 and TDD /
Time slots are allocated by the TDMA control circuits 52 and 152.

The first and second communication interface circuits 53, 57, 1 of the subscriber station 21 and the base station 11, respectively.
53, 157, TDD / TDMA control circuits 52, 15
2, the packet number measuring units 63 and 66, and the slot allocating unit 54 (the request slot allocating unit 55 and the fixed period slot allocating unit 56) respectively include a CPU (central processing unit).
t) is configured by a microcomputer or the like, various programs are installed in a ROM (read only memory) and executed by the CPU. When configured as hardware, the ASIC is used.
(Application specific integrated circuit) and a predetermined function is executed.

For example, the second communication interface circuit 5
Explaining the functions of Nos. 3 and 153, randomly generated variable-length data such as an Ethernet (registered trademark) frame supplied from the terminal 20 to the subscriber station 21 is the second communication interface circuit of the subscriber station 21. At 53, it is divided into upstream fixed length packets Pu. At this time, the second communication interface circuit 53 further adds the recombined information Pu4 including the adjacent packet presence / absence information X to each upstream fixed length packet Pu.

Each upstream fixed length packet Pu is transmitted to the base station 11
Slots are assigned according to the contents of the slot assignment area TS21 from the subscriber station 21 and are transmitted from each subscriber station 21 functioning as a transmitting side device through a wireless line.

Each upstream fixed length packet Pu received on the side of the base station 11 functioning as a receiving side device is recombined information P.
Based on u4 and the like, the second communication interface circuit 153 re-combines the packet, and the presence / absence of a packet loss is detected. Is output.

The same applies to the data supplied from the network 13 to the base station 11, but in this case, the second fixed data packet Pd is divided by the second communication interface circuit 153 of the base station 11 functioning as a transmitting side device. At this time, the re-synthesis information Pd2 including the adjacent packet presence / absence information X is added to each downlink fixed length packet Pd and transmitted to the subscriber station 21 functioning as a receiving side device through a wireless line.

Downlink fixed length packet Pd received by the second communication interface circuit 53 of the corresponding subscriber station 21.
Are recombined based on the recomposition information Pd2, the presence or absence of packet loss is detected, and if there is no packet loss, the packet is transmitted to the terminal 20.

The first communication interface circuit 57,
Explaining the function of 157, for example, one of the data having a fixed data transmission rate (also referred to as a fixed band as described above) supplied as a continuous data stream from the E1 interface 2 or the ISDN interface 4 has a multiplexer function. Selected by the first communication interface circuit 57 having
Is divided into

At the time of division by the first communication interface circuit 57, the uplink fixed length packet Pu further includes a data channel, an E1 interface 2 or an ISDN interface 4, or a channel number Pu4 for identifying them if a plurality of them exist. Is added.

For the data of the fixed data transmission rate, the fixed cycle slot allocating section 56 allocates the time slots of the upstream data area TS15 so that the fixed data transmission rate is obtained, and the E1 interface 2 or the ISDN interface 4 sends the time slot. Data is transmitted from each subscriber station 21 functioning as a transmission side device through a wireless line.

Each upstream fixed length packet Pu received on the side of the base station 11 functioning as a receiving side device is based on the channel number Pu4 and the first communication interface circuit 157.
To a continuous data stream having a fixed data transmission rate (constant rate) and channel number Pu4.
Is output to the E1 interface 6 or the ISDN interface 8 corresponding to the above at the fixed data transmission rate.

The same applies to the data supplied to the base station 11 as a continuous data stream from the E1 interface 6 or the ISDN interface 8. In this case, the first communication interface circuit 157 of the base station 11 functioning as a transmitting side device divides the packet into fixed downlink packets Pd, and at this time, each fixed downlink packet Pd.
Is added with the channel number Pd2 and is transmitted to the subscriber station 21 functioning as a receiving side device through a wireless line.

Downlink fixed length packet Pd received by the first communication interface circuit 57 of the corresponding subscriber station 21.
Is supplied to the first communication interface circuit 57 based on the channel number Pd2 and transmitted to the E1 interface 2 or ISDN interface 4 corresponding to the channel number Pu4.

The communication system 10 to which the embodiment of the present invention is applied is basically constructed as described above.
And it works.

Next, the slot allocation procedure for each radio frame cycle by the request slot allocation section 55 and the fixed cycle slot allocation section 56 which constitute the slot allocation section 54 will be described.
This will be described with reference to the flowchart shown in FIG.

In the flowchart of FIG. 8, step A1,
The process of A2 is a fixed period slot allocation process, and the processes of steps B1 to B5 are requested slot allocation processes.

First, in step A1, the fixed cycle slot allocation unit 56 of the base station 11 allocates the time slot in the downlink data area TS12 of the downlink to the corresponding subscriber station 21.

As an example, the data stream from the E1 interface 6 of the base station 11 is sent to the subscriber station 21 (1).
When transmitting to the E1 interface 2 (1), the period of one radio frame is 2 [ms], and the fixed length data of the downlink fixed length packet Pd that can be assigned to each time slot of the downlink data area TS12. Pd3
Has a data capacity of 128 [bytes], the fixed-cycle slot allocation unit 56 allocates four time slots to one radio frame to obtain 128 × 4 × 8 [bits] /
A data channel of 2 × 10 −3 [sec] = 2.048 [Mbps] can be set.

As another example, the ISD of the base station 11
When the data stream from the N interface 8 is to be transmitted to the ISDN interface 4 (2) of the subscriber station 21 (2), the fixed cycle slot allocation unit 56 allocates one time slot for every eight radio frames. 1
28 × 8 [bit] / 8 × 2 × 10 −3 [second] = 64
A data channel of [kbps] can be set.

Next, in step A2, the fixed cycle slot assigning unit 56 assigns the uplink slot to the subscriber station 21 as in the downlink. This allocation is performed by the corresponding subscriber station 21 in the downlink slot allocation area TS21.
Will be notified.

Next, at step B1, the packet number measuring unit 66 of the base station 11 determines the number of packets accumulated in the downlink buffer for each subscriber station 21 for each subscriber station 21 in the downlink direction by a predetermined period. , At the boundary of the radio frame, the radio frame period (2 m in this embodiment)
Measure every s). The number of accumulated packets addressed to each subscriber station 21 is notified to the request slot allocation unit 55.

Further, in step B2, the request slot allocation unit 55 confirms the number of accumulated packets in the upstream direction notified from each subscriber station 21 from the information of the slot request 71.

The number of packets accumulated in the upstream direction of each subscriber station 21 is measured by the packet number measuring unit 63 of each subscriber station 21 at a constant cycle, for example, at each radio frame cycle, at the boundary of radio frames. This is the number of storage buffers in the upstream transmission buffer 62, and this number of storage buffers is notified to the base station 11 as information (slot request number) of the slot request 71 in the uplink slot request area TS14.

Next, in step B3, the request slot allocation unit 55 stores the remaining time slots allocated by the fixed cycle slot allocation unit 56 in the number of packets stored in the base station 11 and in the subscriber station 21. Based on the number of stored packets, a so-called schedule calculation is performed to distribute the downlink data area TS12 and the uplink data area TS15.

Next, the request slot allocation unit 55, based on the allocation result of the schedule calculation, the subscriber station 21
The number of stored packets addressed to each of the remaining time slots in the downlink data area TS12 is allocated.

Then, the required slot allocation unit 55 notifies the allocation result of the above schedule calculation to the corresponding subscriber station 21 in the downlink slot allocation area TS21.

Hereinafter, E1 interfaces 2, 6 and I
The input data of the fixed band data channel from the SDN interfaces 4 and 8 is the first communication interface circuit 5
7, 157, the packets Pu and Pd having fixed lengths in the upper and lower sides are mounted, and the slots allocated by the fixed period slot allocating unit 56 of the base station 11 are used for the wireless section (upper and lower data areas T
In S15, TS12), the data is transmitted from the base station 11 to the subscriber station 21 or from the subscriber station 21 to the base station 11.

The packets received by the subscriber station 21 or the base station 11 are sent to the first communication interfaces 57, 157.
Is converted into a continuous data stream having a constant data transmission rate, and is output as output data to the E1 interfaces 2 and 6 or ISDN interfaces 4 and 8.

Since the subscriber station 21 has a plurality of data channels such as the E1 interface 2 and the ISDN interface 4, which data channel is identified by the channel numbers Pd2 and Pu4.

On the other hand, randomly generated variable length data such as an ether frame is sent to the second communication interface circuits 53 and 153 by the fixed length packets Pu and Pd.
Is divided into At this time, the recomposition information Pd2 and Pu4 are added.

The fixed-length packets Pu and Pd to which the recombining information Pd2 and Pu4 are added are transmitted to the base stations in the radio section (upper and lower data areas TS15 and TS12) by the slots allocated by the request slot allocation unit 55 of the base station 11. It is transmitted from the station 11 to the subscriber station 21 or from the subscriber station 21 to the base station 11.

The packet received by the subscriber station 21 or the base station 11 is sent to the second communication interface 53, 153.
Are recombined with each other and output to the terminal 20 or the network 13.

As described above, in the above-described embodiment, the radio frame, which is a communication frame having a constant length and including the downlink data area TS12 and the uplink data area TS15 divided into a plurality of time slots, has a constant 2 [ms] cycle. This is applied to a communication system 10 composed of a plurality of subscriber stations 21 and a base station 11 that transmits a packet from a single base station 11 to a plurality of subscriber stations 21 in a time slot of a downlink data area TS12.

In this case, the base station 11 includes the first communication interface circuit 157 as a first data division unit for dividing the data supplied from the external E1 interface 6 or ISDN interface 8 at a fixed data transmission rate into packets. Have.

Further, the base station 11 has a second communication interface circuit 153 as a second data division unit for receiving randomly generated data such as an Ethernet frame from the external network 13 and dividing the data into packets. .

Furthermore, when the base station 11 transmits the packets output from the first and second communication interface circuits 153 and 157 to the plurality of subscriber stations 21 in the time slot of the downlink data area TS12, the first station The packets supplied from the communication interface circuit 157 are preferentially allocated to the downlink data area TS12 by the fixed cycle slot allocation unit 56 so that the fixed data transmission rate is achieved, and the remaining time slots of the downlink data area TS12 are used for the second communication. The request slot allocation unit 55 allocates the packet supplied through the interface circuit 153 and the transmission buffer 65 for each downlink subscriber station.

By allocating the time slots to the packets in this way, it is possible to transmit a plurality of data of a fixed data transmission rate and randomly generated data from the same base station 11 without causing data loss. It can be reliably transmitted to the subscriber station 21. In this case, both the data having a fixed data transmission rate and the randomly generated data can be transmitted from the same base station 11 in the same radio frame, which is economical.

Further, in this embodiment, a radio frame of a constant length including a downlink data area TS12 and an uplink data area TS15 divided into a plurality of time slots is repeated at a constant 2 [ms] cycle, and a single frame is formed. Packets from the base station 11 to the plurality of subscriber stations 21 in the downlink data area TS12.
When transmitting in the time slot of, the base station 11 first transmits the data supplied from the external E1 interface 6 or ISDN interface 8 at a fixed data transmission rate.
As a first data division process by the communication interface circuit 157, it is divided into packets.

Further, the base station 11 is supplied with randomly generated data such as an Ethernet frame from the external network 13 and supplies this to the second communication interface circuit 153.
According to the second data division process, the data is divided into packets.

Further, the base station 11 divides the packets divided in the first and second data division processes and output from the first and second communication interface circuits 153 and 157 into a plurality of packets in the time slot of the downlink data area TS12. When transmitting to the subscriber station 21 of the first communication interface circuit 157, the packet divided in the first data dividing process supplied from the first communication interface circuit 157 is given priority by the fixed cycle slot allocating unit 56 so as to have the fixed data transmission rate. The downlink data area TS12 (periodic slot allocation process), and the remaining time slots of the downlink data area TS12 are
The request slot allocating unit 55 allocates the packets divided through the communication interface circuit 153 through the transmission buffer 65 for each downlink subscriber station and divided in the second data dividing process (request slot allocating process).

By allocating the time slots to the packets in this manner, a plurality of data of fixed data transmission rate and randomly generated data can be transmitted from the same base station 11 without causing data loss. It can be reliably transmitted to the subscriber station 21. In this case, both the data having a fixed data transmission rate and the randomly generated data can be transmitted from the same base station 11 in the same radio frame, which is economical.

Further, in the above-described embodiment, the uplink in which transmission is performed from the plurality of subscriber stations 21 to the single base station 11 and the transmission from the base station 11 to the plurality of subscriber stations 21 are performed. There is a fixed-length wireless frame that is repeated in a fixed cycle including the downlink, and the uplink requires a slot request area TS14 for requesting a time slot from a plurality of subscriber stations 21 to the base station 11 and a plurality of subscriptions. An uplink data area TS15 divided into a plurality of time slots for transmitting a packet from the master station 21 to the base station 11 is included.

In the downlink, a slot allocation area TS21 for notifying the plurality of subscriber stations 21 of the slot allocation in the base station 11 and a plurality of slots for sending packets from the base station 11 to the plurality of subscriber stations 21 are provided. The downlink data area TS12 divided into the time slots is included.

In this case, each subscriber station 21 uses the external E1
A first communication interface circuit 57 as a first data division unit that divides data supplied from the interface 2 or ISDN interface 4 at a fixed data transmission rate into packets, and randomly generated data is supplied from an external terminal 20. A second communication interface circuit 53 as a second data dividing unit for dividing the packet into packets,
The upstream transmission buffer 62 that temporarily stores the packets output from the second communication interface circuit 53, and the number of packets stored in the upstream transmission buffer 62 are periodically measured, and the packets are transmitted through the upstream slot request area TS14. A packet number measuring unit 63 that requests the base station 11 to allocate a time slot.

On the other hand, the base station 11 uses the upstream data area TS
When allocating 15 time slots to each subscriber station 21 by the slot allocator 54, the data transmission rate of the packet transmitted to the base station 11 through the first communication interface circuit 57 of the subscriber station 21 becomes the fixed data transmission rate. Priority allocation so that the upstream data area T
The remaining time slots in S15 are assigned.

Therefore, the data from the E1 interface 2 or 6 or the ISDN interface 4 or 8 which is the data of the fixed data transmission rate can be surely transmitted at the fixed data transmission rate, and the Ether frame generated randomly. And the like can be efficiently transmitted between the terminal 20 and the network 13, and one radio frame can be efficiently used.

Next, FIG. 9 shows a subscriber station 21 of the FDD system.
The structural example of A is shown. FIG. 10 shows a configuration example of the base station 11A of the FDD system. FIG. 11 shows the structure of an FDD wireless frame.

The subscriber station 21A of FIG. 9 of the FDD system, the subscriber station 21 of FIG. 6 of the above-mentioned TDD system, the base station 11A of FIG. 10 of the FDD system and the base station 11 of FIG. 7 of the above-mentioned TDD system, and In the wireless frame of FIG. 11 of the FDD system and the wireless frames of FIG. 2, FIG. 3, and FIG. 4 of the above-described TDD system, the corresponding elements are designated by the same reference numerals, and detailed description thereof will be omitted.

Since the FDD system is frequency-multiplexed, different radio frequencies are used in the up direction and the down direction. Therefore, the switches 43 and 143 forming the high-frequency circuits 32 and 132 of the TDD system are the diplexers 44 and 14 in the FDD system as shown in FIGS. 9 and 10, respectively.
4 is replaced. As is well known, the diplexers 44 and 144 are composed of a bandpass filter for a reception frequency and a bandpass filter for a transmission frequency, and output signals from the transmitters 42 and 142 are fed to the antennas 12 and 22, respectively.
The signal is received by the antennas 12 and 22 and guided to the receivers 41 and 141.

On the other hand, regarding the radio frame, as is apparent from FIG. 2 and FIG. 11, in the TDD method, one radio frame is divided into a downlink and an uplink serially, whereas FDD is divided. In the method, the downlink radio frame and the uplink radio frame are configured in parallel.

The downlink data area TS12 in the downlink radio frame shown in FIG. 11 is the downlink data area TS of FIG.
It has the same configuration as the downlink fixed length packet Pd shown in FIG.

Similarly, the upstream data area TS15 in the upstream radio frame shown in FIG. 11 is the upstream data area T15 of FIG.
It has the same configuration as the upstream fixed length packet Pu shown in S15.

The slot allocation unit 54 shown in FIG. 10 can perform slot allocation processing using the algorithm shown in FIG. 8 as in the TDD system.

The present invention is not limited to the above-described embodiment, but is applied to, for example, a bidirectional optical line in which a base station and a subscriber station are connected by an optical fiber instead of a wireless line as a transmission line. It goes without saying that various configurations can be adopted without departing from the gist of the present invention.

[0109]

As described above, according to the present invention, both fixed data transmission rate data and randomly generated data are transmitted in the same communication frame while maintaining the fixed data transmission rate. Can be made.

Therefore, the communication frame can be used efficiently.

[Brief description of drawings]

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

FIG. 2 is a structural diagram of a downlink data area and a downlink fixed length packet according to the TDD method.

FIG. 3 is a structural diagram of a downlink data area and a downlink fixed length packet.

FIG. 4 is a structural diagram of an upstream data area and an upstream fixed length packet.

FIG. 5 is an explanatory diagram of adjacent packet presence / absence information.

FIG. 6 is a block diagram showing a configuration of a TDD subscriber station.

FIG. 7 is a block diagram showing the configuration of a TDD-based base station.

FIG. 8 is a flowchart showing a slot allocation procedure for each radio frame period.

FIG. 9 is a block diagram showing a configuration of an FDD subscriber station.

FIG. 10 is a block diagram showing a configuration of a base station of the FDD system.

FIG. 11 is a configuration diagram of an FDD wireless frame.

[Explanation of symbols]

2, 6 ... E1 interface 4, 8 ... ISDN
Interface 10 ... Communication system 11, 11A ... Base station 13 ... Network 20 ... Terminal 21, 21A ... Subscriber station 53, 153 ... Second communication interface circuit 54 ... Slot allocation unit 55 ... Request slot allocation unit 56 ... Fixed period slot allocation Units 57, 157 ... First communication interface circuit 62 ... Upstream transmission buffer 63, 66 ... Packet number measuring unit 65 ... Downstream subscriber station-specific transmission buffer 71 ... Slot request 72, 73 ... Slot allocation

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshiyuki Yasui             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation (72) Inventor Yukihide Mizumoto             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation F term (reference) 5K028 AA11 BB04 CC02 CC05 DD01                       DD02 EE12 HH02 KK32 LL02                       LL42 SS24                 5K030 GA03 HA08 HB29 JA01 JA05                       JL01 LC09 LE14                 5K033 CA11 CB06 CB17 DA01 DA19                 5K034 AA02 DD03 EE03 EE10 EE13                       FF02 FF11 FF13 HH01 HH02                       HH63                 5K067 AA13 BB21 CC04 CC08 EE02                       EE10 EE22

Claims (3)

[Claims] 1. A communication frame of a fixed length, which includes a downlink data area divided into a plurality of time slots, is repeated at a fixed cycle, and a packet is transmitted from a single base station to a plurality of subscriber stations in the downlink data area. In the data transmission device for transmitting in a time slot, the base station comprises a first data division unit that divides data supplied at a fixed data transmission rate from the outside into packets, and randomly generated data is supplied from the outside. A second data division unit for dividing the packet into packets, and transmitting the packets output from the first and second data division units to the plurality of subscriber stations in a time slot of the downlink data area, The packets supplied from the first data division unit are preferentially assigned to the downlink data area so as to have the fixed data transmission rate, and the downlink data area is assigned. And a slot allocation unit for allocating the rest of the band to the packet supplied from the second data division unit. 2. A communication frame having a fixed length, which includes a downlink data area divided into a plurality of time slots, is repeated at a fixed cycle, and a packet is transmitted from a single base station to a plurality of subscriber stations in the downlink data area. In the method of using the communication frame in a data transmission device for transmitting in a time slot, in the base station, a first data division step of dividing data supplied from the outside at a fixed data transmission rate into packets, and randomly occurring Data is supplied from the outside, and the base station divides the packet into a second data division step of dividing into packets and the first and second data division steps into time slots of the downlink data area. When transmitting to the plurality of subscriber stations, the packets divided in the first data division process have the fixed data transmission rate. Preferentially allocated to the downlink data region, the method utilizing the communication frame and having a slot allocation process of allocating the remaining downlink data region divided packets in the second data division process. 3. An uplink for transmission from a plurality of subscriber stations to a single base station, and a downlink for transmission from the single base station to the plurality of subscriber stations. There is a communication frame of a certain length that is repeated at a certain period, and in the uplink, a slot request area for requesting a time slot from the plurality of subscriber stations to the single base station, and the plurality of subscribers. An uplink data area divided into a plurality of time slots for transmitting a packet from a station to the single base station is included, and the downlink is allocated to the plurality of subscriber stations by slot allocation at the base station. In the data transmission device including the slot allocation area to be notified, each subscriber station divides the data supplied from the outside at a fixed data transmission rate into packets, and a randomly generated data division unit. Is supplied from the outside and is divided into packets, a transmission buffer for temporarily accumulating the packet output from the second data division unit, and a cycle of the number of packets accumulated in the transmission buffer. Through the slot request area of the uplink,
A packet number measuring unit for requesting the base station to allocate a time slot, wherein the base station allocates the time slot of the upstream data area to each of the subscriber stations, the first of the subscriber stations. The data transmission rate of the packet transmitted to the base station through the data division unit is preferentially assigned so as to be the fixed data transmission rate, and in response to the time slot assignment request from the packet number measurement unit, A data transmission device comprising a slot allocation unit for allocating the remaining time slots of the upstream data area.