FR2520570A1 - LOCAL LOOP COMMUNICATION NETWORK VEHICULATING BOTH DIGITAL TELEPHONE DATA AND SIGNALS IN DIGITAL FORM - Google Patents

Abstract

THE INVENTION RELATES TO A LOCAL LOOP-LOOP COMMUNICATION NETWORK CONTAINING BOTH DATA AND TELEPHONE SPEECH SIGNALS IN DIGITAL FORM. THIS NETWORK INCLUDES A LOOP L SHAPED BY LINES OF LINE 1, SERIES BY REPEATERS R1 TO RN ALLOWING ACCESS TO THE LOOP OF STATIONS SL TO SM, AND CLOSED ON ITSELF BY A UCB LOOP CONTROL UNIT INTRODUCING A PERIODIC SYNCHRONIZATION SIGNAL AND THE DELAY NECESSARY TO FORM A FRAME HAVING A FIRST SEGMENT OPERATED IN "PACKET" MODE AND A SECOND SEGMENT OPERATED IN "CIRCUITS" MODE. TO INCREASE THE TELEPHONE TRAFFIC CAPACITY, THE LOOP IS PURGED OF ITS BYTE IN "CIRCUITS" MODE AT SEVERAL POINTS BY GATEWAYS P1 TO P4 WHICH TAKE THE BYTES OF THE SECOND SEGMENT CIRCULATING IN THE UPSTREAM SECTOR AND INSERT THE OCTS BEFORE THE CIRCULAR SECTOR , A CT TIME SWITCH ENSURING THE INTERCONNECTION BETWEEN SECTORS AND WITH THE EXTERIOR. THE INVENTION APPLIES TO MULTISERVICE LOCAL NETWORKS.

Description

The present invention relates to a communication network

  local loop conveying both data and tele-

  speech systems in digital form, said network comprising a loop composed of sections of transmission lines, connected in series by means of repeaters each allowing access to a station to the loop, and a control unit of loop for closing the loop on itself, to introduce a periodic synchronization signal and complete with a delay the transmission time in the loop to form a time frame, said frame comprising a first segment k bytes to transmit data in "packet" mode, the other bytes forming a second segment being used

  to transmit the telephone communication signals.

  In a local area network carrying both digitized data and voice signals, there is usually a large disproportion between the bit rates required for the flow of these two types of information. public networks, a telephone call requires a permanent bit rate of 128 keb / s, which is relatively

  the data rates required for data transmission.

  The technological limits of flow on the means of trans-

  mission then lead to split them to allow them to provide the necessary bit rate for the voice signals In the case of a looped local network, it is therefore necessary to distribute the subscribers on several separate loops But this then induces problems interconnect complexes for data signals whose throughput

  total does not generally justify such splitting.

  The object of the invention is to overcome this drawback in the case of a looped local network by splitting the transmission means only for the telephone traffic. It consists in purging the loop of its telephone traffic in several points, from

  to allow the transport of several telephone calls.

  two byte numbers of the second segment of the frame.

  According to the invention, this is achieved by a communication network.

  loop local cation of the type indicated above, characterized in that it comprises at least two telephone gateways, each connected to a different point of the loop via a repeater for taking the bytes used from the second circulating segment. on the loop sector upstream of the gateway and to insert the bytes used of the second segment flowing on the loop sector downstream of the gateway, the gateway being transparent to the other bytes, and in that it further comprises a time switch, connected to each gateway and externally by digital multiplex links in both directions of transmission and allowing the interconnection of

  different loop sectors between them and with the outside through

  said links, and a telephone control unit

  ensuring, for each telephone call, the marking of the

  time and the gateways concerned, as well as the allocation, at each station to be connected, of an interval of

  free time of the second segment of the frame.

  The invention will be better understood and other features

  will appear with the following description and accompanying drawings

  o: Figure I shows the schematic diagram of the network according 1 'inrention; FIG. 2 represents the organization of the time frame used; Figure 3 shows an example of a real topology of the loop; Fig. 4 is a diagram of a repeater showing how a gateway or station accesses the loop; Figure 5 shows a possible schematic of the telephone gateway; and Fig. 6 is a time switch scheme for a network according to the invention. FIG. 1 shows the diagram of the general organization of a local loop network according to the invention. This network comprises, in a known manner, a number of trans-transmission line sections li which are connected in series by repeaters RI to Rn A

  UCB loop control unit can close the loop L on it-

  It generates a periodic synchronization signal Sy and introduces a delay which completes the transmission time of the loop to the time separating two successive synchronization signals so as to create a time frame. Each repeater can allow an IS station access to Sm to the loop Each station allows the connection of a number of subscribers attached thereto and can receive the synchronization signal Sy and locate a time interval IT of the time frame by the shift of its passage time relative to at

that of the synchronization signal.

  In addition, a number, here four, of

  telephone gateways P1 to P4 connected to the loop by repeated

  which could be confused with Si stations.

  These gateways divide the loop L into sectors and their role is to take the octets relating to current telephone calls circulating on the upstream sector (with respect to the concerned gateway) of the loop and to insert the corresponding octets circulating on the

  downstream sector The gateways P1 to P4 are all linked to a

  CT time switch is also externally connected via LNE digital links to a conventional private or public PBX. A telephone control unit UCT manages all the telephone communications in the loop L and with the outside It ensures the marking of the time switch, the telephone gateways and the stations It is connected to the loop by means of a

  repeater and sends his orders in a way that will be described below.

  The operation of the assembly will be described with reference also to FIG. 2 which represents the organization of the frame

  temporal This frame has a classical duration of one hundred twenty-five micro-

  seconds and is composed of a number of time slots IT (one hundred twenty-eight in this case) each containing eight bits (ie one byte) transmitted in series The first byte is transmitted

  by the UCB loop control unit and constitutes the sync signal.

  The following k bytes are exploited in "packet" mode and constitute a first segment of the frame. A station Si can transmit a packet if it finds an indication of freedom in the form of a packet.

  token "free" in the first byte J It identifies the station intended

  by the following byte Ad A station If can also receive a packet if it recognizes a "busy" token in the first J byte and its own address in the next byte Ad The k bytes in "packet" mode are transmitted in transparency in the loop L by the stations and gateways which are not concerned by the transmission of a packet. The remaining bytes are operated in "circuits" mode and constitute a second segment of the frame The allocation of one byte per frame is equivalent to a bit rate of 64 keb / s, ie the bit rate required for a communication in one direction The same byte used alternately by two stations on the loop allows the flow of a

  telephone communication in both directions.

  The length k of the "packet" segment is a parameter of the system that can be modified according to the respective values of the telephone and data traffic. According to the invention, the gateways Pj (j worth here from I to 4) purge the loop L of its telephone traffic at several points, from

  to allow the transport of several telephone calls.

  two-byte single-byte numbers of the second segment of the frame

  because of the sampling of the bytes used from the circular "circuits" segment

  In the upstream gateway sector and the gateway insertion of the bytes used flowing in the downstream sector, a byte sent by a station will only encumber the loop until the next

  Likewise, a byte destined for a station does not assume

  will break the loop only since the last upstream phone gateway.

  As already mentioned, the synchronization byte and the packet segment traverse the gateways without modification to the extent that

  the package is not intended for the gateway in question.

  The time switch CT allows the interconnection of the various

  sectors of the loop and these sectors with the outside, via a self-

  private or public switch (not shown) connected to the conutator

time by the LNE links.

  The same byte of the digital frame can be used several times on the loop for different communications in different sectors of the loop, the number of bytes of the segment "circuits" of the frame can therefore, compared to a conventional solution, be reduced for a given traffic and congestion rate, and the segment "packets" can be lengthened in ,, consequence This allows to increase the traffic of

data in "packet" mode.

  The LNI to LN 4 and LNE digital links comprise, in a known manner, a device for setting local time on arrival. If we take for k a value equal to 34, three digital links will be designated by A, B and C, each carrying thirty-one ways, are sufficient

  for a gateway Table I below gives a rule of corre-

  particularly simple between the bytes conveyed by the second segment of the frame and the channels of the three digital links of each gateway in the two directions of transmission For the octets of rank lower than k + 1, the gateway must be transparent for the loop except

  if it is concerned with a packet transmission.

TABLE I

  Byte N Link B Loop N Channel -31

______________ J I J

  Loop byte N Link A N channel N loop byte Channel C N link - It is seen that a communicatio; interesting a station of the sector eompris between the gateways Pj and Pj + I and using the path m of the link B to the gateway Pj one way, uses the channel m of the link B from the gateway Pj + 1 return The switch temporal CT can therefore consider the pair formed by a line to a gateway and the line of the same rank coming from the next gateway as a normal two-way link in which the channels of the same rank carry the signals associated with the two directions of the same communication The switch temporal CT is then feasible in any known manner and conventional,

  the marking of the switch can be done in one operation.

  This is valid for any fixed relationship other than that indicated by

Table I.

  We see that the loss of a digital line going from a

  to the time switch renders the corresponding slots unusable

  weights of the frame for the stations of the sector upstream of said gateway, which decreases the volume of acceptable traffic by these

  On the other hand, the loss of a digital line going from the

  a gateway renders the corresponding frame locations unusable for downstream

  same consequences for the volume of traffic acceptable by this sector.

  If, for reasons of equipment, digital lines of the two directions are matched, it is known that it is advantageous to associate at the level of the time switch the two lines of the same rank and opposite direction serving the same sector; loss of equipment

  then has the same impact as the loss of one of the lines.

  On the other hand, if one associates, for practical reasons, two lines of opposite direction connected to the same footbridge, then the loss of an equipment extends the disturbance both to the sectors in question.

downstream and upstream of the bridge.

  As an example of implantation, FIG. 3 shows a real topology possible for the loop L. In fact, it is possible in practice to use fiber optic cables as transmission lines and then have an optical splitter R from which will leave various loop sectors serving each

  for example a floor or a building body It is then particularly

  easy and convenient to have all the gateways at this splitter R All digital links with the switch

  are then grouped geographically.

  FIG. 4 shows an embodiment of any repeater. This repeater comprises two shift registers Rel and Re 2 connected in series in the loop L. A clock circuit H extracts at the input E of the repeater the element frequency binary signal in the loop It can be assumed, for example, that the information is serialized in the loop according to a code such as the so-called "Manchester" code which allows easy extraction of the binary bit rate. first signal hb at this frequency to the shift registers Rel and Re 2 to allow the information circulating on the loop to pass through the clock circuit H also provides a clock signal h W, synchronized with the time intervals IT of the frame, to the station If or to the gateway Pj associated with the repeater, so that the latter can take the bytes or insert them

  with the right phase The Rel shift register has a parallel output

  connected to the Si station or to the associated Pj bridge for

  The station or gateway inserts the bytes via a parallel input on the Re 2 register. The station or gateway thus has an IT time slot to decide on the change of the byte received until it is correctly set in the register Re 2 If no write order _

  given, the byte passes through the station or the gateway in transparent

  ence. In the case of fiber optic transmission, it is clear that an optoelectronic receiver must be available at the E input of the repeater and a light emitter at the S output. Until now, the most important case has been considered. However, it is possible to envisage another variant according to the invention, in which a certain mutual assistance is provided between the contiguous sectors of the loop to dampen the effect of the loss of a

  digital line or equipment (two associated lines).

  For this purpose, any gateway Pj receives the instruction not to insert on the downstream sector certain channels of its active lines coming from the time switch. The bytes of the corresponding time slots of the frame are then transparently transmitted by

  the gateway and everything happens as if we had created, for these inter-

  vales of time, a new sector between the gateways Pj-1 and Pj + l Depending on the mode of operation chosen, these time intervals can be used for communications for the stations of one

  old sectors or for all stations in the new sector.

  It can be seen that, in this variant, the bytes relating to the two directions of transmission of the same communication are no longer routinely carried by the lines of the same rank of two lines of the same rank serving contiguous gateways The time switch can not be marked in a single operation, there is no longer any interest in matching at the switch the two lines of the same rank going to the gateway Pj and coming from the gateway Pj + 1; on the contrary, it is more interesting to match in the same equipment the two lines of the same rank associated with the same gateway since it is useful to extract a byte from the frame only if we can reuse its location in the downstream sector and that it is harmful to insert a

  byte in a time interval or location that has not been previously

  emptied of its contents In case of fault, the failure of a pair of lines between the gateway Pj and the time switch leads to the transparency of this gateway for all the locations of the frame corresponding to the lost channels and a sharing (defined by the chosen mode of operation) of these locations to serve all the stations of the two sectors concerned The decrease in capacity in

  traffic can be distributed at will between the two sectors.

  It is within the scope of this second variant of the invention that embodiments of a gateway and the time switch will be described in greater detail, with reference to FIGS. 5 and 6. It is clear that correspondences of the type shown in Table I can be established by fully wired means in the gateway But the solution shown in Figure 5 uses a time switch of conventional structure, in which the correspondence between input and output channels In FIG. 5, it is possible to recognize the shift registers Rel and Re 2 of the repeater, the clock circuit E having been omitted. The parallel output of the register Rel is connected to a reception speech memory MP Rj of the associated gateway. Pj This memory MP Rj is write-controlled (input W) by the clock signal h V to store the bytes of all the time slots IT of the second segment of the trailing edge. me (segment "circuits") The bytes to be taken by the gateway are read in the memory MP Rj under the control (input R) of a reception time memory address MAT Rj in which are marked, by a logic for marking LM Nj, the locations of the memory MP Rj to be read The memory MAT Rj itself is read in synchronism with the time intervals of the second segment of the frame under the control of the signal h The bytes read in the speech memory MP Rj are sent to a demultiplexer / parallel-serial converter device DM Xj which, under the control of the signal hw, distributes in series form the bytes, read in the memory MP Rj in parallel form, to the corresponding channels of the digital multiplex lines A ' j, B'j and C'j ranging from the gateway Pj to the time switch CT In a similar way, on transmission, the

  bytes to be inserted are received on the channels of the digital multiplex

  Aj, Bj and Cj coming from the time switch CT These bytes are transmitted in parallel form to a transmission speech memory MP Ej

  via a multiplexer / serial converter device

  parallel M Xj controlled by the clock signal h As for reception, the transmission speech memory MP Ej is associated with a transmission time memory memory MAT Ej read in synchronism with the time intervals of the second segment of the frame (signal h on w the read input R) to control the reading of the speech memory

  MP Ej transmission at the locations marked by the marking logic LM Pj.

  The speech memory MP Ej is connected to the parallel input of the shift register Re 2 via a transfer gate circuit 10 which

  authorizes the transfer of bytes to the Re 2 register only for

  Time Values o The bytes on the loop must not be transmitted transparently (bytes of the "packet" segment and bytes of the

  second segment to be transparently transmitted because of the way in which

  The locations of the octets to be transparently transmitted are entered in a transmission authorization memory MA Ej

which controls the gate circuit 10.

  Finally, the marking logic LM Pj has access to the "packet" channel of the loop by a PC link whose details, conventional, have not been represented and which allows the collection via the register Rel packets addressed to the gateway and the insertion of packets by the register Re 2 when the channel is free The marking logic LM Pj is thus connected to the telephone control unit UCT

  from which she receives the marking orders.

  Local HR delivery circuits are planned for

  the arrival of the digital lines Aj, Bj and Cj.

  The operation of the whole is easily deduced from the

  description above The bytes to be taken are read from the memory of

  HP Rj at the locations marked in the temporary address memory.

  MATT Rj and sent to the time switch CT on the corresponding channel of the digital line A'j, B'j or C'j according to the matching rule adopted The bytes to be inserted are likewise registered in the speech memory MP Ej which is read at the locations marked in the time address memory MAT Ej, the authorization to insert being provided by the transmission authorization memory HA Ej The marking of

  this last occurs only in case of reconfiguration of the system.

  An advantage of using such a communication arrangement

  time for the gateways is first that it is very close to the one used for the stations, which must be able to associate on demand the time slots operated in "circuits" mode of the frame

  and the channels serving the active subscribers connected to it.

  Another advantage is to allow the masking of a d 6 fail-

  launches by changing the look-up table when the current value of parameter k causes all channels serving a

  Gateway can not be used simultaneously.

  FIG. 6 is a time switch diagram CT in the case of the second variant of the invention It essentially comprises a speech memory MP in which the bytes of all the channels of all the incoming lines A'I to C'4, from the gateways, and A'e to C'e, veuanut from the outside, are inscribed synchronously to the rhythm of the h Local Tor R 'after passing through a multiplexer / serial-parallel MX device This memory MP is read

  (R input) to the locations marked in a time-sensitive address memory.

  MNT reads under the control of the local clock R 'The marking in the memory MAT is carried out by means of a logic of marking LU receiving the orders directly from the control unit talphonique UCT Bytes read in the speech memory MP are transmitted on the corresponding channels of the lines AI to C 4 and Ae to Ce of the links to the gateways and to the outside via a demultiplexer device / DMX parallel-series converter. local HR discount are provided upon arrival of

  digital lines in the time switch CT.

  Such a switch can be built around a speech memory of five hundred and twelve words and could serve then for example

  three bridges in three lines each and seven lines to the outside.

  higher traffic would require more complex TST-type structures, for example, without the operation of the system.

be modified in principle.

  Table II below gives three examples of connection to illustrate the operation of the switch of FIG. 6 and its marking. Case 1 is that of a local communication between two stations respectively placed on the sectors if included between the gateways P1 and P 2 and S 3 included between gateways 53 and 54 Case 2 is that of local communication between two stations located

  on the same sector I of the loop Case 3 is that of a communication

  cation between an SI station and the outside.

TABLE II

  In case 1, two markings are necessary to associate in both directions of transmission the time intervals 92 and 107 of the frame,

  respectively allocated to the connection in the two sectors concerned.

  In case 2, a single marking is sufficient to loop back on itself the chosen frame location through the time switch In the

  case 3 finally, two markings, one in the sense of trans-

mission.

  The identity of the time slots allocated to a communication

  cation is transmitted to the stations and gateways concerned by the telephone control unit UCT via the channel "packets" of

the frame.

  Of course, the embodiments described are not

  in no way limitative of the invention.

Empla Canal

Sector: External cement sector

  Station 1 Station 2 framing Marking 1 Marking 2

11 2

  1 IF S 3 92 107 4.11 1.27 B 2.27 C 3.11

  2 SI if 92 92 B 2.27 B 1.27 3 have 92 Ae 13 A'e 13 B 127 B 2.27 Ae 13

_ 1 3 12,7 1

Claims (5)

  A looped local communication network carrying both digital voice data and speech signals, said network comprising a loop consisting of transmission line sections, serialized with repeaters each allowing access from a station to the loop, and a loop control unit to close the loop on itself, to introduce a periodic synchronization signal and complete with a delay the time of transmission in the loop to form a time frame, said frame having a first k-byte segment for transmitting data in "packet" mode, the other bytes forming a second segment   being used to transmit the telegraphic communications   said network being characterized in that it comprises at least two telephone gateways (P1 to P4), each connected at a different point of the loop (L) via a repeater (R1 to Rn) for taking the bytes used from the second segment flowing on the loop sector upstream of the gateway and inserting the bytes used of the second segment flowing on the loop sector downstream of the gateway, the gateway being transparent to the other bytes, and it further comprises a time switch (CT), connected to each of the gateways and externally by digital multiplex links (LNI to LN 4; LNE) in both directions of transmission and allowing interconnection of the different loop sectors between them and with the outside via said links, and a telephone control unit (CPU) ensuring, for each communication   telephony, time switch (CT) marking and   (P1 to P4) concerned, as well as the allocation, at each station (SI to Sm) to be in communication, of an interval of   free time (IT) of the second segment of the frame.   2 Local loop communication network according to the   cation 1, characterized in that the telephone control unit (UCT) is connected to a repeater (Ri) of the loop (L) and sends the marking commands of the gateways (Pj) and stations (Si) through the channel in   "packets" mode constituted by the first segment of the frame.   3 Local loop communication network according to one of the   claims i or 2, characterized in that each repeater comprises   two shift registers (Rel, Re 2) in series in the loop (L) and a clock circuit (H) for extracting from the signal at the input the frequency 13 -   binary element and for providing a clock signal (h) at this frequency, which controls the shift of the registers, and a clock signal (h), synchronized with the time intervals of the frame, at the station ( Si) or to the gateway (Pj) associated with the repeater, the first register (Rel) having a parallel output through which the gateway or station can read the contents of said first register and the second register having a parallel input through which the gateway or the station can register at a desired time interval a byte in this second register instead of the byte that appears therein, the repeater transparently transmitting the bytes for which the gateway or the associated station does not come to write a new byte in the second shift register.   4 Looped local communication network according to any one   one of claims 1 to 3, characterized in that some of the   Telephony gateways do not pick up all used bytes circulating on the upstream loop sector, but let some of them by transparency, so as to create loop sectors   elongated for the corresponding time intervals.   Local loop communication network according to any one   conque of claims 1 to 4, characterized in that each gateway   telephone comprises: a reception speech memory (MP Rj) connected to the first shift register (Rel) of the associated repeater and controlled synchronously with the writing to store the bytes of all the time slots (IT) of the second segment the frame;   a reception time memory memory (MAT Rj) read in synchronization   with the time intervals of the second segment of the frame for controlling the reading of the reception speech memory (MP Rj) at the marked locations; a de-multiplexer / parallel-serial converter device (DM Xj) for distributing the read bytes in the reception speech memory (MP Rj) to the corresponding channels of the digital multiplex lines (A'j, B'j, C'j) ranging from the gateway (Pj) to the time switch (CT); a transmission speech memory (MP Ej) connected to the second shift register (Re 2) of the associated repeater, via a transfer gate circuit (10), and commanded to write in synchronism with the time intervals of the second segment of the frame for storing the bytes to be inserted in the loop (L); a serial-parallel multiplexer / converter device (M Xj) for collecting the bytes from the different channels of the digital multiplex lines (Aj, Bj, Cj) from the time switch (CT) and sending them to the transmit speech memory ( MP Ej) at the corresponding time intervals of the second segment of the frame;   a transmission time memory memory (M & T Ej) read in synchro-   nisue with the time intervals of the second segment of the frame to control the reading of the broadcast speech memory (MP Ej) at the marked locations; a transmission authorization memory (MA Ej) in which are inscribed the time slots of the first and second segments of the frame where the octets of the loop must be transmitted in transparency by the associated repeater, the output of this memory commander the transfer gate circuit (10); and marking logic (LM Pj) having access by the repeater to the "packet" channel of the loop constituted by the first segment of the frame and providing, under the control of the telephone control unit (CPU),   the marking of the time address memories (MAT Rj, MAT Ej) neces-   to the establishment of the transiting telephone by the bridge (Pj).   6 Local loop communication network according to one   any of claims 1 to 5, characterized in that said   Time domain (CT) essentially comprises: a speech memory (MP) in which the speech bytes are recorded cyclically; a multiplexer / serial-parallel converter (MX) device for collecting the bytes coming from the different channels of the digital multiplex lines (A'j, B'j, C'j, A'e, B'e, C'e) coming from bridges (Pj)   and from the outside and send them to the Speech Memory (HP) at inter-   corresponding time slots of the local frame determined by the clock signals (H ') of the time switch (CT); a time address memory (MAT) read in synchronism with the time slots of said local frame to control the reading of the speech memory (MP) at the marked locations; a demultiplexer / parallel-serial converter (DMX) device for distributing the read bytes in the speech memory (HP) to the corresponding channels of the digital multiplex lines (Aj, Bj, Cj, Ae, Be, Ce) from the time switch (CT ) walkways (Pj) and outdoors; and   a marking logic (LM) connected to the telephone control unit   (UCT) to ensure the marking of the temporary address memory. (MAT).