DE3536874A1 - Time division multiplex transmission method for digital narrowband and broadband signals with access of terminals to a common 16 kbit/s signalling channel - Google Patents

Abstract

Service integration in ISDN is implemented primarily on the subscriber connection line. For connection of the different subscriber terminals corresponding to these services, provision is made at the user/network interface such that one 16 kbit/s common signalling channel D is made available along with the two 64 kbit/s information channels B. The method by which the narrowband terminals gain access to the D-channel is defined in CCITT Recommendation I.430. In a future broadband ISDN with a preferably optical subscriber connection line, high-speed services, e.g. moving picture services, are planned along with the aforementioned narrowband ISDN services. In order now to be able to implement access for broadband terminals also according to the access method defined in CCITT Recommendation I.430, the structure of the broadband pulse frame is selected in the time division multiplex transmission method according to the invention in such a way that the D and E bits occur in each case in individual bits in the pulse frame for the broadband transmission at the interval of roughly half the octet cycle duration (62.5 mu s), the position of the D bits being selected in such a way that an overlap occurs with the position of the D bits for the narrowband transmission access method.

Description

The invention relates to a time division multiplex transmission ver drive for digital narrowband and broadband signals, which is a signaling channel according to the preamble of claim 1.

DE-AS 12 77 302 describes a signaling method for a Telecommunications network with several types of traffic, such as Fern speak, data transmission and telex known. The Telecommunications network contains a number of message channels, combine the two or more offices and additionally one or more paths between the offices for the transmission of one or more signals channels. The control information is in the signal channels mations for the news channels, i.e. those Information needed to build and monitor night straightening connections required by each of these offices becomes. In DE-AS 12 77 302 is between the individual A common signaling network for participants different types of traffic (e.g. telephone subscribers, Telex subscribers, etc.) provided, which also in the large signaling network the data signal channels are better used. Here is a concentrator between each office or distributor provided, which the control information mation of all facilities of the different traffic ar merged or in the distributor again the different to which traffic types are assigned.  

When setting up an integrated digital communications network ISDN , precautions must also be taken for network access and communication processing for the cooperation between devices for voice, text, data and image communication. In telcom report 6 (1983) issue 3, pages 166 ff., The architecture of the subscriber access is described, which was defined in CCITT recommendation I. 430. At the SO interface between the network and the subscriber, two user channels (B channels) with 64 kbit / s each and one signaling channel (D channel) with 16 kbit / s are available for message transmission simultaneously and in both directions.

Via the D channel, this is required for both B channels Liche subscriber signaling transmitted. This part Subscriber signaling involves communicating more generally Information between connected subscriber endge councils and network, e.g. about present and not done third-party connection requests, fee information and the like Lich, as well as the transmission of information on service-specific treatment of the connections on the B channels including connection control structure with changing terminal configuration (participant stations with several devices on one connection). Except for transmitting signaling information the D channel can also be used to transmit packet-oriented subscriber or telemetry data to be used. However, the higher priority must be used the signaling information can be ensured.

The subscriber stations are connected in ISDN with a so-called network termination NT , which is connected via the connection line to a line termination LT of the switching center. Line termination LT and network termination NT assume the transmission-related tasks of sending and receiving the narrowband signals with a net bit rate of 144 kbit / s, whereby the tasks of clock supply and synchronization, the error limitation by looping and the remote supply are connected.

At the interface between the subscriber and the network, the so-called SO interface, up to eight end devices can be connected in ISDN , which can access the D channel independently of each other. In order to ensure that while a subscriber terminal is carrying the message, other subscriber terminals do not start transmitting the messages, CCITT recommendation I. 430 stipulates that initially all of the terminals coming to the network termination via the D channel In addition to their transmission to the exchange, D bits are individually sent back to the terminals in a special D echo channel via the SO interface. The electrical properties of the SO interface are selected so that a logical "0" always dominates when different end devices simultaneously send a logical "0" and a logical "1" in the D channel (wired-or). In the D echo channel (E bit) a logical "0" is sent back from the network termination NT, so that the terminal which has sent a logic "1" to the network termination NT recognizes this deviation and sends its message before the next one is sent D bits aborts.

In a future broadband ISDN , preferably with an optical subscriber line, in addition to the aforementioned ISDN narrowband services, services with higher transmission bit rates (eg moving picture services) are planned. While using existing copper lines this integration is limited to services that can manage with a maximum of two 64 kbit / sB channels, there are no restrictions regarding the capacity of the connecting line. To access the network at the self-service interface for connecting a broadband terminal for the integration of broadband services on the subscriber line an access procedure is to be defined. If the broadband terminal is to be accessed using the access method specified in CCITT recommendation I. 430, a possible solution for this is to connect the broadband terminal via a multiple line to the network termination NT . The broadband terminal is connected on the one hand like a narrowband terminal to the SO bus and is connected in parallel to this via a broadband connection (on which only the broadband information is transmitted) to the network termination NT . Such a solution of the common D-channel access has the disadvantage that an additional line is required between the broadband terminal and the SO bus, which means that the requirement for a transmission technology integration already taking place in the terminal is not met.

The invention has for its object a time multi plex transmission method for digital narrowband and Broadband signals to indicate that in the CCITT recommendation I. 430 for narrowband terminals also set access procedures for Breit's access band terminals can be used with.

According to the invention, this object is achieved by a time multi plex transmission method with the features of the patent claim 1 solved.  

In terms of signaling, the one with an Hx-Ka nal extended broadband connection a basic connection equal, both of them on the D channel (with 16 kbit / s) access. This also applies to the Transfer of low rate and high rate parts of the Overall signal a simple summary or spread given. With the time division multiplex according to the invention This is the first time that transmission methods are possible was created, that in the CCITT recommendation I. 430 given access procedures also with a broadband Single connection to apply. Via the D-channel echo function can in the terminals by observing these echo bits (E-Bit) the access authorization can be controlled.

With the time-division multiplex transmission method specified in claim 2, the phase relationship specified in CCITT recommendation I. 430 for transmission and reception frames for narrowband transmission can also be adhered to for pulse frames of broadband transmission in a simple manner. A similar processing of the signaling information in the broadband network termination B-NT is thus ensured.

Is according to claim 3 one of the two B-channels are in the CCITT Recommendation I. replaced 430 specified channel structure through the wideband channel Hx, it can drive case in notbe with a power-saving Bateriepufferung a simple switching to the basic operation without the high ratigen part of the total signal made of the .

Due to the uniform specified in claim 4 Subdivision of the octet period is the circuit expenditure compared to an uneven lower part lung less. The requirement of transferring two D bits per octet period in the pulse frame of the Breit bandsignals is easy fills.  

Another advantageous embodiment of the time multiple plex transmission method is in claim 5 specified.

The invention is described below with reference to the drawing illustrated embodiments described in more detail and he purifies. It shows:

Fig. 1, the subscriber terminal configuration for a single broadband connection with a schematic representation of the access method,

Fig. 2 shows a possible pulse frame structure for the connection of a narrowband and a broadband terminal and

Fig. 3 shows an embodiment for a pulse frame according to the invention.

Fig. 1 shows the subscriber line configuration for the connection of a broadband terminal B-TE via a copper line or fiber to a broadband network termination B-NT . The broadband network termination B-NT is connected via a connection line ASL to a broadband line termination B-LT , an optical fiber being preferably used for the connection line ASL . The broadband network termination B-NT can contain an adaptive clock adaptation on the input side at the broadband interface SB . By the dashed lines in the broadband network termination B-NT , the D-channel echo function is supposed to be Darge. The broadband network termination B-NT sends back a D bit received by the broadband terminal B-TE or narrowband terminal TE in the echo channel in a corresponding bit position to all terminals assigned to this D channel. The access authorization can now be controlled by observing these E bits in the terminal.

The narrowband terminals TE are connected via a bus, preferably via a copper line, to the broadband network connection B-NT . In the time-division multiplex transmission method according to the invention, the channel structure defined in CCITT recommendation I. 430 with B + B + D 16 is expanded by a broadband channel Hx , with regard to signaling a broadband terminal B-TE a base connection terminal TE is equivalent since both terminals access the D 16 channel. The constellation of the broadband terminal B-TE is the same as for a narrowband terminal TE with a basic connection, which is not connected in a bus configuration but a star configuration.

The broadband channel Hx has the n times the bit rate of the B channel. The E and D bits specified in the CCITT recommendation I. 430 are each arranged individually at intervals of approximately half the octet period (62.5 μs) in the pulse frame for the broadband transmission in such a way that for the position of the D -Bits a temporal overlap with the location of the D bits for the access method of narrowband transmission occurs. In Fig. 2, the pulse frame structure for the narrowband and broadband transmission is shown in its structure. Important requirements for narrowband transmission are:

• - Relation to the octet clock
  The octet clock for the B channels is determined by the frame length of 250 µs. The time periods for the synchronization are shown in FIG. 2 by hatched fields.
• - Division of the D channel
  The D bits (and correspondingly the E channel bits in the transmission direction from the broadband network termination B-NT to the narrowband terminal TE) are divided into four bit positions with approximately the same spacing in the 250 μs time-division multiplex frame.
• Round trip delay
  Time barriers for the round trip delay are determined by the requirement that the broadband network termination B-NT must insert a D bit received from the narrowband terminal TE at the assigned E bit position so that it is at the narrowband terminal TE before the next one is sent D bits can be received.

The above specifications depend on the subscriber line configuration. Since a mixed configuration of bus for narrowband terminals TE and star for broadband terminals B-TE is required in FIG. 1, the conditions for a star configuration are significant for the signaling at the interfaces SO and SB . From the relative position of the two SO frames in the narrowband terminal TE , there is a maximum permissible round trip delay of 42 microseconds (corresponding to 8 bits), an adaptive clock adaptation (not shown) being provided on the receiving side of the broadband network termination B-TE .

As can be seen from the preceding statements, the pulse frame structure for broadband transmission is to be increased before that the conditions for the D-channel access control are met. An essential condition concerns the temporal position of the D bits and their E bits sent back from the broadband network termination B-NT as an echo to the broadband terminal B-TE within the respective frame for the two transmission directions.

Leave out of the pulse frame for narrowband transmission the following characteristics for broadband transmission derive:

• - block structure
  The frames for both directions of transmission are divided into eight equally long periods of time, which are repeated in accordance with the octet cycle with 125 μs and whose duration corresponds to a three-bit length of the pulse frame for the narrowband transmission.
• - Block assignment for D and E channel
  As already stated, the D or E bits must occur in the pulse frame for broadband transmission at intervals of approximately half the octet period of 125 µs in single bits. In the direction from the broadband network termination B-NT to the broadband terminal B-TE , a D bit and an E bit are arranged in the fourth and eighth time periods. In the direction from the broadband terminal B-TE to the broadband network termination B-NT , a D bit is arranged in the fourth and eighth time period. In consideration of the D-channel echo function, the E-bit must have arrived in the broadband terminal B-TE before the next D-bit is sent. For this purpose, the D channel is assigned a bit in the second half of the fourth and eighth time period and the E bit is arranged in the first half of the fourth and eighth time period of the pulse frame for broadband transmission.
• -Time relationship
  In the broadband network termination B-NT , the pulse frame for the broadband transmission in the direction of the broadband terminal B-TE is in a fixed time relationship to the pulse frame for the narrowband transmission. The time relationship for this results from the best possible coverage of the three-bit groups around the D-bit for the narrowband transmission with the timing of the D-bit in the fourth and eighth period of the pulse frame for broadband transmission. The delay of the transmission frame for the broadband transmission compared to the transmission frame for the narrowband transmission is preferably ge selected equal to the bit duration of the narrowband frame, ie the time offset TBNT is one bit. The reception and transmission frames for the broadband transmission in the broadband terminal B-TE must have a fixed time relationship to one another, as also in the case of narrowband transmission. A delay of two bits of the narrowband frame is preferably selected for the transmission frame compared to the reception frame of the broadband transmission. Taking into account the above-mentioned time relationship, the condition of the maximum permissible rotational deceleration with a star configuration of approximately 40 microseconds is met.

Taking into account the aforementioned requirements, the Transition times between the respective D and E bit Broadband broadcasting positions in the area of the narrowband transmission specified values from 8 to 10 Bit.

FIG. 3 shows an embodiment for a pulse frame taking into account the conditions explained with reference to FIG. 2. The broadband channel Hx with a bit rate of n * 64 kbit / s replaces one of the two B channels in the channel structure B + B + D 16 of the basic connection, so that the expanded channel structure Hx + B + D 16 results for the broadband transmission. The broadband pulse frame made up of eight equally long time segments with a frame duration of 125 µs is divided into a further two equally long sections in each time period. As a display form for the wideband channel Hx with n bits per time interval 3, the row-column shape is in Fig. Chooses ge. In Fig. 3 the pulse frame for the transmission direction from the broadband network termination B-NT to the broadband terminal B-TE is shown. In the reverse direction of transmission, the E bits are omitted in the fourth and eighth time period, column 1. F is used to denote bit positions for synchronization and monitoring. The n bits per time period are divided into two halves, each with a 1-bit column in front for the transmission of the narrowband channels. At the beginning of the first section in the fourth and eighth period, the E bit and at the beginning of the second section in the fourth and eighth period, a D bit is arranged. Narrowband transmission includes:

• - A D and E channel with 16 kbit / s each second or first half of the fourth and eighth Period
• - A B channel with 64 kbit / s as a distributed octet and
• - A synchronization channel with 32 kbit / s with four equidistant bit positions in the pulse frame. To ensure synchronization, a check for code violation for the first synchronization bit can also be provided by using the last synchronization bit as a parity bit.

The time-division multiplex transmission method according to the invention is preferably used for the standardized broadband channel HO with 384 kbit / s. The circuit arrangement for time-division multiplex transmission can be easily built on, in particular the multiplex control can be carried out simply by the uniform subdivision of the pulse frame for broadband transmission.

Claims (5)

1. Time division multiplex transmission method for digital narrowband and broadband signals, which has a signaling channel with a bit rate of 16 kbit / s, to which narrowband terminals access according to the access method defined in CCITT recommendation I. 430, characterized in that that for access by broadband terminals (B-TE) with a broadband channel Hx , the structure of the broadband pulse frame is chosen so that in the CCITT recommendation I. 430 specified D and E bits each for itself at intervals of approximately half the octet period (62.5 µs) occur one bit at a time in the pulse frame for broadband transmission, so that the position of the D bits of the broadband transmission is covered by a time overlap with the position of the D bits for the access method the narrowband transmission he gives. 2. Time division multiplex transmission method according to claim 1, characterized in that in the direction from the broadband network termination (B-NT) to the broadband terminal (B-TE) or narrowband terminal (TE) the transmission frame for the broadband transmission compared to the broadcast frames for narrowband transmission are delayed by the bit duration of the narrowband frame (TBNT = 1 bit) and that for broadband transmission in the broadband end device (B-TE) the transmission frame is two bits of the narrowband frame (TBTE = TTE 2 bit) compared to the receiving frame is delayed. 3. Time division multiplex transmission method according to claim 1, characterized in that one of the two B channels of the channel structure defined in the CCITT recommendation I. 430 B + B + D 16 is replaced by the broadband channel Hx , which the n- times the bit rate of the B channel, so that the expanded channel structure Hx + B + D 16 results for the broadband transmission. 4. Time-division multiplex transmission method according to claim 1, characterized in that the octet period is divided into eight equally long periods of time that in the direction from the broadband network termination (B-NT) to the broadband terminal (B-TE) in the fourth and eighth Period a D-bit and E-bit are arranged and that a D-bit is arranged in the direction from the broadband terminal (B-TE) to the broadband network termination (B-NT) in the fourth and eighth period. 5. Time division multiplex transmission method according to claim 4, characterized in that the time periods in two equally long sections are divided, with am Beginning of the first section in the fourth and eighth Period one E bit and at the beginning of the second Section in the fourth and eighth period D bit is arranged.