JP2981112B2 - Spread spectrum communication data transmission system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for transmitting various kinds of data by a spread spectrum communication system, and more particularly to a system for effectively utilizing a data transmission channel.

[0002]

2. Description of the Related Art In a spread spectrum communication system using direct spreading, a transmitting side multiplies data to be transmitted by a spreading code sequence and spreads a signal over a wide band before transmitting. On the other hand, the receiving side reproduces the original information data by correlating (despreading) the received signal with the same spreading code sequence.

In this system, channels are distinguished by a spreading code sequence to be multiplied. The signals of a plurality of channels are transmitted overlapping on the frequency axis and the time axis, and when viewed from the receiving side, the signals of the other channels act as apparent noise (interference) when despreading. The magnitude of this noise (interference) is one factor that determines the number of usable channels.

A spread spectrum communication data transmission system for transmitting various types of data output from a plurality of terminals and having different data transmission speeds and allowable delay times by using this spread spectrum communication method has been proposed. A transmission channel use management station for managing the use of the channel is provided, and the management station assigns a spread code sequence, which is a data transmission channel, to each terminal requesting the transmission channel.

In this conventional system, as shown in FIG. 3, use control of a transmission channel is performed by the following algorithm.

Step 1: A terminal desiring to transmit data (transmitting terminal) outputs a request for a data transmission channel and a destination to the transmission channel use management station by using a control channel.

Step 2: The management station has a list for storing the status of use of the transmission channels, and checks whether there is an unused transmission channel from the list. If there is an unused transmission channel, step 3; assign the channel to the transmitting terminal requesting the transmission channel, and step 4; update the list.

In step 2, if there is no unused transmission channel, the management station does nothing. as a result,
The channel request of the transmitting terminal naturally ends in a timeout state.

When the management station notifies the transmitting terminal of the allocated transmission channel using the control channel, the receiving terminal can also receive it and know the allocated transmission channel. The transmitting terminal transmits data using the assigned transmission channel, and the receiving terminal receives data transmitted on this channel.

[0010] When the transmission is completed, step 1: the transmitting terminal notifies the management station of the release of the transmission channel using the control channel, and step 4; upon receiving the notification, the management station updates the list.

[0011] By managing the use of transmission channels in such a procedure, as shown in FIG. 4, the number of terminals (A to H) that transmit using the same frequency in this system can be reduced by the interference level between channels. The maximum number x of simultaneously usable spreading channels determined by the above (x = 6 in FIG. 4)
More can be set. In this case, if the number of simultaneously transmitting terminals is always equal to or smaller than x (the range indicated by a circle in FIG. 4), the problem of interference does not occur.

[0012]

However, in the conventional spread spectrum communication data transmission system, when a plurality of transmitting terminals are simultaneously using the x transmission channel, a new terminal transmits high priority data from a new terminal. Even if there is a transmission request, it cannot be accepted.

As for asynchronous and real-time data (tolerant of delay), such as voice, data transmission is intermittent and includes a time when data is not transmitted. To enhance
It is also contemplated to allow the use of transmission channels beyond the number x. However, even in this case, if the number of terminals transmitting data happens to be larger than x (FIG. 4).
In this case, there is a problem that the level of the interference wave in that time zone becomes large, the desired wave cannot be received well, and the bit error rate becomes high.

An object of the present invention is to solve such a conventional problem and to provide a spread spectrum communication data transmission system capable of efficiently transmitting data by effectively using channels. I have.

[0015]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a spread spectrum communication data transmission system for performing data transmission by a direct spread spectrum communication system.
The priority of the transmitting terminal is determined according to the allowable delay of transmission data transmitted in a burst by the transmitting terminal, and when the transmitting terminal requests a spread code of a data transmission channel, If there is no vacant channel, the data transmission of the transmission terminal having a lower priority than this transmission terminal is stopped, a transmission channel is allocated to the requested transmission terminal,
The transmitting terminal that has stopped data transmission is waiting for an idle channel.

[0016]

[0017]

The assignment of a data transmission channel (spreading code) to a transmission terminal is performed by a transmission channel management station. When the transmission terminal receives a request for a transmission channel from the transmission terminal, the management station allocates a vacant channel if any. Is assigned to the transmitting terminal that has made the request. When there is no free channel, the management station interrupts data transmission of the transmitting terminal having a lower priority than the transmitting terminal that has made the request, and instructs to stop the data transmission. The terminal that has received the command terminates the transmission at a well-separated place, releases the transmission channel, and shifts to a channel waiting state. The management station allocates the released transmission channel to the requesting transmitting terminal. If the sender requesting a channel has a lower priority than any sender currently using the channel,
The transmitting terminal which has requested the channel is shifted to a state of waiting for an empty channel.

Further, since each terminal transmits data in a burst, the probability that data transmission timings from a plurality of terminals overlap will decrease, and the interference level between channels will decrease.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a spread spectrum communication data transmission system according to an embodiment of the present invention, each terminal transmits a signal in bursts. In transmitting data, each terminal requests a data transmission channel from a transmission channel use management station. The transmission channel use management station that has received the request is shown in FIG.
The use of the data transmission channel is controlled by the procedure shown in (1). FIG. 2 shows a timing chart and a request, interrupt, and release protocol of the transmission channel at this time.

In FIG. 1, step 1; terminal A, which wants to transmit data, indicates to the management station B, using a control channel, the classification of the terminal number of the transmission destination and the degree of allowable delay. It outputs information such as the data type and a request to use the data transmission channel. These pieces of information are also received at the receiving terminal C at the same time.

Step 2: the management station B, having received the channel request from the terminal A, searches the transmission channel usage status list to see if there is any available transmission channel. If there is, the management station B allocates a transmission channel to the terminal A that has newly output the transmission request, and step 4: updating the record of the usage status table.

The management station B notifies the transmitting terminal A of the allocated transmission channel using the control channel. This notification is also received by the receiving terminal C , and the transmitting terminal A and the receiving terminal C execute data transmission using the assigned transmission channel.

Step 5: In step 2, if there is no available transmission channel, the transmission data of the terminal currently using the transmission channel and the transmission data of terminal A which has newly output the transmission request are transmitted. The priority order between the transmission data types is determined according to each transmission data type. If there is a terminal currently transmitting data having a lower priority than the transmission data of the terminal A among the terminals currently using the transmission channel, Step 6: Instruct the terminal to stop data transmission through the control channel. This stop instruction is also received by the receiving terminal.

The terminal that has received the stop instruction terminates the transmission at the earliest good point, transmits a transmission end signal to the management station B using the control channel, and releases the transmission channel. On the other hand, the receiving terminal knows the transmission stop command, receives the transmission end signal and knows the end of transmission, and temporarily ends the reception.

Step 7: The terminal that has stopped data transmission is queued for transmission channel assignment.

If there is a vacancy in the transmission channel due to the suspension of data transmission, step 3: assign a transmission channel to terminal A transmitting high priority data, and step 4: update the record of the usage status table.

If it is determined in step 5 that the priority of the data transmitted by the terminal A is lower, step 7: the terminal A is arranged in the transmission channel assignment queue.

Even if the same terminal requests a plurality of times, only one transmission channel is allocated to one terminal. It is also assumed that one terminal is stored in the channel assignment queue.

When the data transmission of the terminal using the transmission channel is completed and the transmission channel is released when the transmission channel has been used up, step 3; Allocate the released transmission channel to the terminal transmitting the highest priority data among the terminals in the queue, and step 4: update the record in the usage status table.

As described above, in the spread spectrum communication data transmission method according to the embodiment, since each terminal transmits data in bursts, the probability that data transmission timings from a plurality of terminals are overlapped is reduced, and the transmission between channels is reduced. A reduction in the interference level can be expected. In addition, since transmission channels are assigned in consideration of the priority of transmission data, efficient data transmission can be performed when multiple types of data are transmitted by a spread spectrum communication method using direct spreading. Therefore, this method can realize effective data transmission in a data transmission system in which various types of data having various differences in data transmission speed and allowable delay are mixed.

[0031]

As is apparent from the above description of the embodiments, the spread spectrum communication data transmission system of the present invention
By assigning transmission channels in consideration of priority,
Efficient data transmission becomes possible. In addition, the transmission channel can be effectively used, and as a result, the frequency use efficiency can be improved. Further, by allocating the functional channels, the traffic volume of the entire data transmission system can be averaged, and the interference between channels can be reduced in combination with the burst data transmission.

[Brief description of the drawings]

FIG. 1 is an algorithm showing a control procedure of a spread spectrum communication data transmission method in an embodiment of the present invention;

FIG. 2 is a diagram showing a transmission channel use request, an interrupt, and a release sequence in the data transmission method according to the embodiment;

FIG. 3 is an algorithm showing a control procedure in a conventional spread spectrum communication data transmission system,

FIG. 4 is a diagram showing a problem of a conventional spread spectrum communication data transmission system.

[Explanation of symbols] 1 to 7 channels A to H terminals

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04B 1/707 H04Q 7/28 H04Q 7/38

Claims (1)

(57) [Claims] In a spread spectrum communication data transmission system for performing data transmission by a spread spectrum communication system using direct spreading, a priority of a transmission terminal is set to an allowable delay of transmission data transmitted by the transmission terminal in a burst manner. When the transmitting terminal requests a spread code of a channel for data transmission and there is no available channel, the transmitting terminal which has lower priority than the transmitting terminal is stopped and the requested transmission is performed. A spread spectrum communication data transmission method, wherein a transmission channel is allocated to a terminal, and the transmitting terminal, which has stopped data transmission, waits for an idle channel.