JPS60256247A - Information transmission system - Google Patents

Abstract

PURPOSE:To detect simply and surely the frame end of a transmission packet by transmitting a packet data from a medium attachment unit MAU to a carrier band transmission line after the packet data from an information processing unit is subjected to scrambling and coding. CONSTITUTION:A scramble code NRZ is inputted to an exclusive OR circuit 11 of a data transmission section of the MAU of the information transmission system and inputted to a shift register 2 in synchronizing with a clock signal. Outputs of the 1st-8th stages are outputted in parallel with a comparator 13, compared with a start frame delimiter SFD pattern preset in a register 14 so as to detect the SFD in the packet data. Further, a data signal from an information processing unit is set to a hold circuit 16 via an AND circuit 15. A hold circuit 17 is reset by setting the circuit 16 and the output next to the register 12 is inputted to the circuit 17. Then the packet data is outputted from the modulator 23 and end of frame of the transmisson packet is detected simply and surely.

Description

[Detailed Description of the Invention] (Technical Field of the Invention) The present invention relates to a plurality of information processing units connected to a carrier band transmission path via an attachment unit interface.
It relates to an information transmission system that modulates and transmits packets between RMs.

[Technical background of the invention and other issues]

Recently, fully decentralized protocol transmission systems such as C8 to IA/CD (Carrier Sense Multiple Access 7, 'Collision・Detection) method has been developed. This method performs baseband transmission via a coaxial cable as a transmission path, but recently, in order to use the coaxial cable more efficiently, the baseband signal is modulated into a carrier band signal. The development of so-called broadband networks for transmitting information and making effective use of the transmission band is underway.

In this type of broadband network, a medium attachment unit (MAU) that connects the information processing units of the 11 transmission bands transmits, for example, the Manchester code provided by the information processing device. SK modulated, this MSK change! The I signal will be transmitted via the carrier band transmission path. However, as international standardization of the carrier band transmission path is progressing, it is necessary to reduce the bandwidth of the transmission signal (Ivl S K modulation signal) to 18 MHz or less, and the Manchester code can be converted to N as it is. - There is a problem that it is difficult to perform ISK modulation. Therefore, it has been considered to convert the scrambled NRZ code into -Ross crumpled N RZ i'T n, set its highest frequency to 5 M tlz, and transmit this scrambled NRZ code by MSK modulation. There is.

However, the data from the information processing device is
If the Manchester code described above is scrambled into NRZtVFj and transmitted through SK modulation, then
A problem has arisen in that the delimitation of the packet, which is composed of a plurality of data frames, becomes unclear. This unity, in the MAU that receives the N.I.S.K. modulated signal and restores the packet data,
- A problem arose in that it became impossible to detect the end of the data frame, and the process of restoring data from bucket 1 continued indefinitely, adding an extra column to the end of the frame. Therefore, it has been considered to include a postamble for detecting the end of a frame in the above bucket. However, if this J: is used, a circuit will be required to prevent a boss pattern from occurring in the data frame, or another control channel will be required. There were some problems, such as the need to establish one.

[Purpose of the invention]

The present invention has been made in consideration of these circumstances, and its purpose is to
Scramble data NRZ? ``The object of the present invention is to develop an information transmission system that can easily and reliably detect the end of a frame of a transmitted packet when modulating and transmitting the same.

(Summary of the Invention) The present invention provides a method for modulating and transmitting packet data between a plurality of information processing devices via a carrier band transmission path using a bus-type fully distributed peer-to-peer protocol transmission method.・After data is scrambled and NRZig encoded, the scrambled NRZi signal is modulated and sent to the carrier band transmission path. After transmitting the final bit of the packet data, the modulated signal is cut off at a bit timing within (n-1) bits, and when the packet data is received, Count the number of received bits, before! ii1! The apparatus is configured to detect the end of reception of the packet data by detecting a surplus bit string of (n-1) bits or less. In particular, the medium attachment unit transmits the preamble and start frame delimiter of the packet data consisting of a plurality of data fields without scrambling, and also transmits the packet data without scrambling. At the time of reception, a clock is recovered from the preamble, and the received signal is descrambled from the next bit of the start frame delimiter according to the recovered clock to restore packet data.

−6= (Effect of the invention) Thus, according to the present invention, when packet data is scrambled, modulated, and transmitted, the medium attachment unit I~
After transmitting the last bit, the modulated signal is cut at a bit timing shorter than the n-bit length of the plurality of n-bit data fields that make up the packet data, so the modulated packet data is received. Medium Attachment 1~ On the unit side, by multiplying the bit length of the data frame by Ki, it is possible to reliably detect the end of the frame by detecting a sequence that is less than the predetermined bit length. . Therefore, bucket 1~
・Even if the data is scrambled and then modulated and transmitted,
Packets and packets are extracted from the signal obtained by demodulating the modulated signal.
It becomes possible to reliably detect only the data, and the conventional problems caused by scrambling can be effectively compensated for. Therefore, packet data transmission can be efficiently performed via the carrier band transmission path, and a great practical effect can be achieved.

(Embodiment of the Invention) Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

Figure 1 shows the medium attachment 1-(M
FIG. 2 is a schematic configuration diagram of a data transmitting unit that constitutes an AU. This data transmitter performs scramble NRZ encoding processing on Manchester encoded packet data given in the format shown in FIG. 2 from the information processing 1! It is intended to be sent to a channel (not shown). Also, Figure 3 is above! ! [! M.A.
The configuration of the data receiving section of U is shown. A plurality of information processing apparatuses are connected to the carrier band transmission path through MAUs each having such a data transmitter and a data receiver, thereby constructing an information transmission system.

The MAU shown in this example is CC] TT.

It has a scrambler and a descrambler with V23 series interface specifications, converts the bucket I~ data indicated by a Manchester code series into a scrambled NRZ code series, and converts the scrambled N
The RZ code is MSK modulated and transmitted.

Now, for the packet data, as shown in FIG. 2, for example, the unit of frame is 1 byte (8 bits 1~),
7 by 1~ preamble, 1 by 1~ 5FD (start frame delimiter), 2 or 6 bytes destination address, 2 or 6 bytes source address, 2 bytes data length code, transmit data , and has a packet structure with a 4-byte frame check sequence. Of these, the sequence from the destination address to the frame check sequence is called a frame. Then, as described above, this packet data is transferred from the information processing device to the MAU.
It is given as a hemandiesta code.

The data transmitter of the MAU converts the code series into an exclusive OR (EX-OR) circuit 11 as shown in FIG.
The signal is inputted via the shift register 12 and transferred to the 23-stage shift register 12 in synchronization with the clock signal described below. This Shift 1 to Regisc 12 1 "Each output from the 9th to 8th stage (SFD pakun outputted in parallel from the J comparison circuit 13 and preset in the register 14") 110
10101”.This comparison circuit 1
3, the SFD during the packet taking is detected.

On the other hand, when the MAU receives the Manchester code tJn, it regenerates the clock and converts it into the Manchester code or NRZ code according to the clock. Further, when a signal indicating a transmission state is received from the information processing device, that state is sent to the hold circuit 1G via the AND circuit 15. This hold circuit 1
By setting G, the hold circuit 17 at the next stage is reset and prepared for SFD detection by the comparison circuit 13. The hold circuit 16 is reset by the extinction of the data signal, and is prepared for the next packet/γ-data transmission.

However, now, 7 by 1 - (7 x 8 bits) Buri = 10
- When an ampoule is input to the shift register 12, and following this preamble, a 1-byte (8-bit) SFD is input to the shift register 12, the comparison circuit 13 detects this and sets the hold circuit 17. do. By setting this hold circuit 17, in other words, before &l! science fiction
Upon detection of D, the gate circuits 18 and 19 are opened, and the output signal of the 18th stage of the shift register 12 and the signal outputted through the 23rd stage are passed through the EX/OR circuit 20 to the EX of the input stage. -Feedback to the OR circuit 11. By feedback of this data, the input signal becomes
It will be scrambled by the clock fl of 0M) lz.

That is, the bucket 1~ data is scrambled from the destination address data input next to the SFD and converted into scrambled NRZ code. It goes without saying that the preamble and SFD are not scrambled because the data feedback loop is not formed before the detection of the SFD.

The signal transferred to the shift register via the EX-OR circuit 11 is supplied to a D-type 7 lip-flop (D-FF) 21 on one side, and is successively latched in synchronization with the clock signal. There is. The 1@month latched in this D-FF 21 is transmitted to the modulator 23 via the gate circuit 22 controlled by the data signal.
supplied to

This modulator 23 is, for example, before &! The signal scrambled by the 10MHz clock is converted to MSK XIJ? The modulation operation is controlled by the data signal. That is, the modulator 23
begins its modulation operation when the data signal is input, and when the upper two data signals are exhausted, that is, when it finishes sending out the R last bit of the data from bucket 1,
The modulation operation is stopped at pitch 1 to timing within the 7-bit length of the scrambling code, for example, at pitch 3 timing. Note that this modulation operation stop timing is set by, for example, activating a predetermined timer.

In this way, the MAU modulates and transmits the preamble and SFD of the packet data consisting of Manchester code given from the information processing III as is, and then modulates the data after the SFD of the packet data, that is, the destination.・The data from the address to the frame check sequence is scrambled and NRZ encoded, which is then modulated and transmitted. Then, a packet consisting of this scrambled NRZ code is
After the transmission of the R final bit of data is completed, the modulation signal is cut off at a bit timing of less than 1 byte length (for example, 3 bit timing).

Now, the data receiving section of the MAU on the side that receives the packet data sent out in this manner is configured as shown in FIG. 3, for example. The modulated signal received via the carrier band transmission path is input to the 1i modulator 31 and demodulated.

A clock reproducing circuit 32 consisting of, for example, a PLL circuit is connected to the demodulator 31, and the clock component is regenerated from the preamble and SFD transmitted without being scrambled. The shift registers 33 and 34 are transferred and driven by this reproduced clock. 23
The shift register 33 having a stage configuration receives the output signal of the demodulator 31, and the outputs from the first stage to the eighth stage are outputted in parallel to the comparison circuit 35, and the SFD pattern "11010101" set in the register 36 is outputted in parallel. It is compared and collated with °′. The hold circuit 37 is set according to the SFD detection result by the comparison circuit 35.

Then, the gate circuits 38 and 39 are opened by the ZI- of the hold circuit 37, and the shift I register 3 is opened.
The data through the 18th and 23rd stages of 3 is EX-O
It is extracted via the R circuit 40. This output is EX/OR
The signal is led to a circuit 41 and subjected to exclusive OR processing with the output of the II modulator 31. That is, the scrambled NR
The Z code is descrambled. In other words, the descrambler in the data receiving section is basically constructed in the same way as the scrambler in the data transmitting section, and descrambles only the scrambled signal as described above.

On the other hand, the thus descrambled signal is input to the shift register 34 and delayed by 8 bits. Thereafter, the 8-bit delayed signal is sent to the EX/OR circuit 4.
2, the signal is exclusive-ORed with the clock signal, and is applied to the information processing device via a gate circuit 43. The frame end detection circuit 44 detects the end of the frame of packet data in response to the above-mentioned O-check signal and the output of the gate circuit 38, and this frame end detection circuit 44 detects the gate opening of the gate circuit 43. is controlled. That is, the frame end detection circuit 44 counts the number of bits of the received data in units of bytes, taking advantage of the fact that the frame has a length of 8 bits. In other words, the clock signal is counted in units of 8 bits by utilizing the fact that the number of bits of a frame is an integral multiple of 8 bits. Then, when the output from the gate circuit 38 disappears during this 8-bit medium counting operation and the 8-bit counting is not completed,
Since the number of bits in that frame is less than the specified number of bits, this is detected as surplus bits after the previous frame.

In this way, when the frame end detection circuit 44 detects a surplus bit string of less than 8 bits, the gate circuit 43 receives the packet delayed by exactly 8 bits in the shift register 34. This means that the surplus pins 1 to 1 are being supplied. Therefore, when the frame end detection circuit 44 detects a bit string that is less than the 8 bits 1~, it ends the opening of the gate circuit 43 with the next 8 bits 1~.

In other words, Fig. 4 shows the RF carrier of the modulation signal, the clock,
111! The output of the frame detection circuit 44, the descrambled NRZ signal, and the 8-pi-delayed
As shown in the timing of the RZ code, the modulated signal is cut off at 3-bit timing after the last bit of the packet data is transmitted, so that the reception (
RF carrier number 8 disappears. J.J. determines whether or not the above-mentioned 8-bit 81 number is set at the extinction timing of this RF carrier.

Thus, it is determined whether the frame constituent requirements are satisfied or not, and the end of the frame of the packet data is detected at this point.

Thus, with such a data receiving section, it is possible to detect the end of a frame of a transmission packet very easily and reliably. Therefore, when packet data is scrambled, modulated, and transmitted, it is completely unnecessary to insert a postamble into the packet, for example, for detecting the end of a frame, and no additional traffic is generated due to the postamble. In addition, postamble detection circuits and control channels are unnecessary, and M
It becomes possible to simplify the configuration of the AU.

Furthermore, the 7-byte preamble can be fully utilized for clock reproduction, which provides great practical effects such as stabilizing the operation.

Note that the present invention is not limited to the above embodiments. For example, the scrambling method etc. may be determined according to the interface specifications.

17- Also, the number of bits per packet, etc. may be determined according to the information transmission specifications. In short, the present invention can be implemented with various modifications without departing from the gist thereof.

[Brief explanation of drawings]

The figures show an embodiment of the present invention, in which Fig. 1 is a schematic diagram of the scrambler R of the data transmission section of the MAU, Fig. 2 is a diagram showing the data structure of a packet, and Fig. 3 is a diagram showing the scrambler of the MAU data transmission section. FIG. 4 is a schematic configuration diagram of the descrambler of the data receiving section, and FIG. 4 is a timing diagram showing the detection of the final frame of the data receiving section. 11, 20.40.41.42...Exclusive OR circuit (EX/OR circuit), 12.33.34...Shift] register, 13°35...Comparison circuit, 14.36
...Register, 15.18.10゜22, 38.3
9.43...Gate circuit, 1G, H, 37...Hold circuit, 21...D flip-flop (D-F
F), 23...Modulator, 31...Demodulator, 32...
- Clock regeneration circuit, 44...frame end detection circuit. Applicant's agent Patent attorney Takehiko Suzue 18-

Claims (3)

[Claims] (1) When packet data is modulated and transmitted between multiple information processing devices via a carrier band transmission path using a bus-type fully distributed peer-to-peer protocol transmission method, each of the information processing devices is connected to the carrier band transmission path. The medium attachment unit consists of a frame consisting of a plurality of fields in units of n pits. After transmitting the bits, the modulated signal is cut at a bit timing within (n-1) bits, and when the packet data is received, the number of received bits is counted, and the surplus within the (n-1) bits is counted. An information transmission system characterized in that the end of reception of the packet data is detected by detecting a bit. (2) The information transmission system according to claim 1, wherein the medium attachment unit scrambles packet data from the information processing device, modulates and transmits the scrambled signal. (3) Medium Attachment i~・Konitsu 1− is used for preamble and star 1 of the packet data consisting of a frame consisting of multiple fields.
The frame delimiter is sent without scrambling, and when receiving bucket 1 data, the clock is recovered from the preamble, and the received signal is decoded from the next pick after the start frame delimiter according to this recovered clock. The information transmission system according to claim 2, which scrambles the information.