JPH0795743B2 - Frame transmission system of network - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a local area network (LAN) or a metropolitan area network (MAN) in office automation (OA), factory automation (FA), etc. Division multiplexing (TD
M) system network frame transmission system.

[Technical background of the invention and its problems]

Conventionally, in the TDM loop network,
A system in which a frame having a frame length of 125 μs as shown in FIG.

This frame is composed of a slot G0 containing a synchronization pattern and management data and data slots G1 to G5. Slots other than the synchronization and management slot G0 are dynamically allocated for circuit switching or packet switching.

Such a frame is significant in the following points if the transmission speed is about 32 Mbps.

That is, there is a synchronization pattern about every 4000 bits.

The frame is divided into five groups, and the group assignment is dynamically changed without communication between the packet-switched station and the circuit-switched station, so that all stations on the loop can be assigned to any group. It should be accessible.

However, when the bandwidth is expanded to 400 Mbps with this method, the following problems occur.

First of all, if a frame with a length of 125 μs is constructed at 400 Mbps, one frame has about 50,000 bits, and the frequency of occurrence of the synchronization pattern is too small once every frame, and there is a problem that the possibility of loss of synchronization increases. .

Second, the logic circuits that make up each station of a loop network with a transmission speed of 400 Mbps use expensive ICs and LSIs that generate large amounts of heat, such as ECL, but handle station and circuit switching that handle packet switching. If the logic circuit of each station is configured so as to have the function of accessing the entire band without communication with the station, there is a problem that the cost becomes high.

[Object of the Invention]

The present invention has been made to solve the above problems, and provides a frame transmission system of a network that has a synchronization system that effectively uses the band in a broadband network and that can simplify the configuration of each station and reduce the cost. The purpose is to provide.

[Outline of Invention]

That is, to achieve the above object, the present invention provides a frame transmission system of a network, which comprises a transmission line and stations connected by the transmission line, and which transmits a frame on the transmission line to perform communication. Frames of a plurality of systems consisting of a plurality of subframes configured as a fixed-length slot sequence are multiplexed on a transmission path by the slot unit, and each station receives only the slot of the frame used by itself Means for separating at the end and means for multiplexing this slot at the transmitting end of the own station, all of the subframes have a synchronization pattern of a format different from the normal slot, and this synchronization pattern is the system It is characterized by having information indicating.

Example of Invention

 Hereinafter, the present invention will be described with reference to the drawings.

FIG. 1 is a frame configuration diagram of an embodiment of the present invention.

The basic unit of this frame is the data part 1a and the C bit 1b which is the complement of the last bit of the data.
The data slot 1 is composed of

The data slots 1 ₁ to 1 ₅₁ and the synchronization slot 2 form a subframe 3, and the subframes 3 ₁ and 3 ₂
... 3 ₃₀ constitutes a flume 4 with a length of 125 μs.

The sync pattern in the sync slot 2 of the subframe 3 is different from the normal data slot 1 and the C bit is not the complement of the previous bit but has the same value as the previous bit.

Further, in the network of this embodiment, frames of four systems are multiplexed and transmitted on the transmission path.
The two frames are independent of each other and have a length of 125 .mu.s as described above. When this is multiplexed and sent to the transmission line, it is multiplexed in units of slots as shown in FIG. That is, the four systems are A system, B system, and C system.
In the case of the system and the D system, the A system slot is followed by the B system slot, the C system slot, the D system slot, and the A system slot, and the multiplexing is sequentially performed not for each bit but for each slot cyclically.

The structure of the synchronization pattern of this embodiment will be described in more detail. As shown in FIG. 3, a system designating bit 2 consisting of the first two bits indicating which of the four systems is present.
₁ and the subframe number bit 2 ₂ that indicates the subframe number that consists of the next 5 bits, and the normal complement rule 2
One of '1' is more structure as non-complimentary bit 2 ₃ consisting of bits.

The frame transmission method using such a frame structure and synchronization pattern has the following advantages.

That is, since there is a synchronization pattern for every 468 bits in one system, the next synchronization pattern appears at about 1800 bits even when multiplexed.

The sync patterns are never all '0' or all '1'.

The transmission lines can be shared by independent media such as packet exchange in A system, voice line in B system, image line in C system, and high-definition still image in D system, and parts other than multiplexing and demultiplexing circuits can be shared. Since it only needs to operate at 1/4 the speed of the transmission line, it is possible to reduce the cost and heat generation of LSIs.

In this embodiment, the frame in which the subframe number is included in the synchronization pattern has been described, but the synchronization pattern is not the subframe number as shown in FIG.
5μs length of the first subframe and other subframes of 1-bit flag 2 ₄ frames '0', also by indicating with '1' are possible synchronization detection subframe, similar to this Example You can expect an effect.

In this case, by allocating '1' and '0' to the remaining bits ₂₅ at the same ratio, at most 7 out of 9 bits ('0' is at least 2) and at least 4 is at least 4. Pieces (up to 5)
Therefore, it is possible to bring the mark rate close to 50%.

Further, in the above embodiments, the data slot is composed of 8 bits of the data part and 1 bit of the complementary bit, but the empty / closed bit or the speed adjustment bit is added to this to make the slot 10 bits or 11 bits. Even if configured, the effectiveness of the present invention is not impaired. This is because, in multiplexing, each system is multiplexed for each slot instead of for each bit. If multiplexing is performed for each bit, the operation of complementary bits is required at the time of multiplexing, which is extremely complicated.

〔The invention's effect〕

As described above, since the present invention is configured to multiplex and transmit frames of a plurality of systems, wiring can be efficiently performed, and each station separates and processes only the frames used by itself. The processing can be performed at a speed lower than the speed of the transmission path, and the heat generation amount and cost of the logic circuit can be reduced.

[Brief description of drawings]

FIG. 1 is a frame configuration diagram in an embodiment of the present invention,
FIG. 2 is a diagram for explaining the multiplexing of the embodiment, FIG. 3 is a configuration diagram of a frame synchronization pattern of the embodiment, FIG. 4 is a configuration diagram of a synchronization pattern of another embodiment, and FIG. It is a frame block diagram of the conventional frame transmission system. 1 ... Data slot 2 ... Synchronization slot 4 ... Frame

Claims (2)

[Claims] 1. A frame transmission system of a network comprising a transmission line and stations connected by the transmission line, for transmitting a frame on the transmission line for communication.
Frames of a plurality of systems consisting of a plurality of subframes each configured as a fixed length slot sequence are multiplexed on the transmission path in units of the slots, and each station transmits only the slots of the frames used by the station itself. It comprises means for separating at the receiving end and means for multiplexing this slot at the transmitting end of its own station, all of said subframes have a sync pattern of a different format than the normal slot, and this sync pattern is said A network frame transmission method characterized by having information indicating the system. 2. A frame transmission system for a network according to claim 1, wherein said slot is composed of data and complementary bits, and said synchronization pattern ends with a bit which does not comply with complementary regulations.