GB2293728A

GB2293728A - Process for allocation of multiplex channels in a communication system

Info

Publication number: GB2293728A
Application number: GB9517868A
Authority: GB
Inventors: Juergen Hamann; Harold Linke; Karl-Heinz Hass; Viktor Karell
Original assignee: Siemens AG; Siemens Corp
Current assignee: Siemens AG; Siemens Corp
Priority date: 1994-09-30
Filing date: 1995-09-01
Publication date: 1996-04-03
Anticipated expiration: 2015-09-01
Also published as: DE4435136A1; ITMI951946A1; FR2725336B1; GB9517868D0; ITMI951946A0; GB2293728B; IT1277611B1; DE4435136C2; FR2725336A1

Description

2293728 Process for the allocation of multiplex channels in a

communication system The present invention relates to a process for the allocation of multiplex channels in a communication system.

From the document Special edition telcom report and the Siemens magazine "COMI ISDN In The Office", Siemens Aktiengesellschaft, 1985, ISBN 3-8009-3846-4, especially pages 58 to 63, a modular structured digital communication system is known, which presents a unified system for the transfer of voice, text and data. The modular system structure is embodied by a structure of independent functions within the communication system, whereby internal interfaces between these individual functions are provided. - Significant functions are the interface system, the interface and the central control.

In the interface system, connection interface devices serve as the interface between the communication system and terminals having different communication type or which use a different signalling process. At any given time a certain number of similar connection interface devices are arranged on a terminal hardware module, and are described in relation to their specific interface function as users of terminal hardware modules, e.g. SLMD (Subscriber Line Module Digital), SLMA (Subscriber Line Module Analog), SLMB (Subscriber Line Module Burst) or as line terminal hardware modules for exchance calls and cross connection links.

The choice and assembly of terminal hardware modules is carried out in accordance with the terminal configuration to be operated and in accordance with the communication requirements appearing in the communication network.

In the known communication system several terminal hardware modules, which are described in the prior art as interface modules, are connected functionally and constructively to a so-called line trunk unit (LTU). The line trunk units show compatible module locations for a certain number (e. g. 20) of terminal hardware modules. Each line trunk unit is connected over four voice-data-multiplex channels (each 2048 Kbit/s) to each of 32 time slots with an interface. The terminal hardware modules are at least organisably divided up into two so-called halves, which are individually attached to a number of terminal hardware modules. Both halves - and therewith the terminal hardware modules attached to these halves - are dual, that is arranged as a pair of multiplex channels. A HDLCsignalling channel (2-Mbit/s) is provided for an exchange of information between the terminal hardware modules and a central control.

All terminal hardware modules have the same internal system interface. For voice-data transmission a connection is provided on two multiplex channels, socalled PCMHighways, so that for the terminal hardware modules within a line trunk unit halves are associated with the relevant terminal hardware modules. Hence a first or a second pair of multiplex channels is available as a function of the line trunk unit for an allocation of time slots.

Within the bounds of further development, terminal hardware modules with coupling devices for four multiplex channels together are proposed, these terminal hardware modules being available for allocating both the two multiplex channels of one half and also the two multiplex channels of the other half of a line trunk unit. All in all these proposed terminal hardware modules, which are described below as second terminal hardware modules, (the known terminal hardware modules are described below as first terminal hardware modules), can be assigned in a traditional multiplex channel structure with a maximum of 128 time slots.

The problem of the present invention is to ensure that, with an asynchronous balanced mode with first and second terminal hardware modules within a line trunk unit, a distribution which considers the needs of other terminal hardware modules, especially first terminal hardware modules, is carried out on both available pairs of multiplex channels by second terminal hardware modules with regard to the allocation of time slots.

According to a first aspect of the invention there is thus provided a process for the allocation of multiplex channels in a communication system having a number of time slots, for the transmission of telecommunications voice and data signals between connection interface devices and an interface, wherein first connection interface devices have available only a first pair of multiplex channels and second connection interface devices have available in addition at least one further pair of multiplex channels for allocation, and wherein for making a telecommunications connection via the second connection interface device, a central control will select one of the available pairs of multiplex channels of the second connection interface devices in dependence upon the following, which relate to a pair of multiplex channels:- a number (e) of first connection interface devices (AE(ABG1)), a number (g) of first and second connection interface devices, a number (m) of time slots available in the concerned pair of multiplex channels, a number (f) of free time slots in the concerned pair of multiplex channels, wherein the quotient of number (e) and number (g) forms a utilisation factor (p), the product of utilisation factor (p) and number (m) forms a threshold value (T), and the product of utilisation factor (p) and the number (f) form a demand factor (b), and wherein with regard to the first pair of multiplex channels, in the case of a number (f) greater than threshold value (T), the said first pair will be selected for allocation, otherwise the pair for which the difference between number (f) and demand factor (b) is the largest will be selected.

According to a second aspect of the invention there is provided a communication system comprising first connection interface devices and second connection interface devices and two pairs of multiplex channels having multiple time slots, wherein the first connection interface devices are connected to a first pair of the channels and the second connection interface devices are connected to both pairs of the channels and wherein control means is provided which is adapted to select the multiplex channels to be used by said second connection interface devices in accordance with a rule requiring it to consider the current utilisation of the system and to leave the first devices still usable at the highest possible capacity level.

The benefit of the process of embodiments of the invention, which is aimed at terminal hardware modules which are connectable on more than two multiplex channels, can be seen to its full advantage. With the help of the process an equal utilisation of both pairs of multiplex channels in a line trunk unit may be achieved through the use of a smaller number (as a rule, one is sufficient) of these second terminal hardware modules. An equal utilisation of both pairs of multiplex channels of a line trunk unit serves to avoid the overload situation found in the prior art, in which a combination directed over terminal hardware modules of a line trunk unit half must be rejected, because this pair of multiplex channels allocated with a line trunk unit half is completely engaged, whether indeed the other pair of multiplex channels allocated with a line trunk unit half still had free time slots. The process of the invention serves generally to increase the connection throughput.

A further significant advantage of the process of the invention is to be seen in the low processing cost which is obtained by the execution of the process. In addition the process of the invention can be included in the program structure of the existing communication system without major changes of the same being necessary.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, purely by way of example, to the attached drawings in which:

Fig.1 shows the interface system of a communication system Fig.2 shows the static input parameters in mathematical presentation with a flow chart M illustrating the individual steps of the process In figure 1 a communication system schematically shows the significant components for an understanding of the invention. These are, in detail, line trunk units LTU1,-,LTUx, of which only a first LTU1 with the components belonging to it is shown, an interface SN, which is connected with the line trunk units LTU1,-,LTUx over two pairs, i.e. 2 x 2 multiplex channels M', M'', and a central control CC, which is linked up via a signalling channel SIG to the line trunk units LTU1,-,LTUx and connected via a control channel STK with the interface SN. The line trunk units LTU1,-,LTUX, of which only the first terminal hardware module LTU1 will be mentioned below, show a plurality of terminal hardware modules ABG1, ABG2, of which first terminal hardware modules ABW are only connected to one pair M' or W' of multiplex channels and second terminal hardware modules ABG2 show a connection to both pairs M' and W' of multiplex channels.

The line trunk unit LTU1 is organised into two halves L', L'', whereby a pair M' or W' of multiplex channels is allocated with one of the halves L', L''. In the present embodiment the multiplex channels M' are logically allocated with the half L' and multiplex channels W' with the half L''.

The first terminal hardware modules ABG1, which are linked to the pair M' of multiplex channels, will be regarded as allocated with the half L' and the first terminal hardware modules ABGi, which are linked to the pair W' of multiplex channels, will be regarded as allocated with the half L''.

The pairs M', M- of multiplex channels serve the bidirectional transfer of voice and data signals between the line trunk units AE and the interface SN, whereby each pair M', W' of multiplex channels from a multiplex channel with 32 time slots leading to the interface SN and a multiplex channel with 32 time slots coming from the interface SN exist, which are available for telecommunications connections. For a detailed explanation of the individual components presented as well as their function, refer at the outset to the already mentioned prior art or for example to European patent no. 034 76 44.

Besides the first terminal hardware modules ABG1 there exists in the line trunk unit 1 at least a second terminal hardware module ABG2, which is analogously allocated to the first terminal hardware modules ABGi either of the first or other half W, W' of the line trunk unit LTU1. In the drawing the terminal hardware modules ABG1, ABG2 allocated with one of the halves W, L- are bordered by a broken line.

Since the second terminal hardware modules ABG2 also show a connection on the pair of multiplex channels allocated to the other half, the question in the foreground is when, i.e. under what circumstances, should a connection of time slots, in which the pair of multiplex channels are allocated to the other half, be carried out. At this point it should be mentioned that in cases in which only second terminal hardware modules ABG2 exist in one line trunk unit, no problems to be solved by the present invention arise.

A connection strategy for the multiplex channels by a second terminal hardware module ASG2, in such a way that firstly all time slots in which the pair M, of multiplex channels assigned to second terminal hardware module ABG2 must be occupied, before a connection in the second pair M'' of multiplex channels not allocated with it can ensue, has shown itself to be extremely disadvantageous, since with the first terminal hardware modules ABGi allocated to the same half (as the second terminal hardware module ABG2) no time slots are available any longer, although in the other pair M' ' of multiplex channels as many time slots as you like would 10 be available.

The decision when a time slot in which the pair M'' of multiplex channels is not allocated should be connected by a second terminal hardware module ABG2, is made by the central control CC, and the relevant second terminal hardware module ABG2 is controlled by the central control CC according to the decision made.

In figure 2 are shown the required static input parameters for the decision-making of the central control CC, as well as a flow chart(diagram) showing the details of steps in the decision-making process with the help of mathematical symbols.

Values are provided for the static input parameters, which are defined by the system architecture or the present system configuration, that is to say independent of a respective connection or allocation situation. Principally the input parameters are always to be understood in relation to a line trunk unit half L', L''. Which half L', L'' a present input parameter x relates to will be expressed by x(L') or x(L'').

As static input parameters there are provided in 35 detail:

e(L'); e(L'') the sum of all connection interface devices AE, which are arranged on the first terminal hardware module ABGi of a half, g W); g W ') the sum of all connection interface devices AE on first and second terminal hardware modules ABG1, ABG2 allocated to a half, m(L'); m(L') number of time slots in which a pair of multiplex channels are allocated to a half (e.g. m=64), p(L1) e(W)/g(L') p(L11) e(L')/g(L'') an individual utilisation factor for a half def ined as quotient of e and g, TW) p(L') x m(L) T(L'') PW') x m(L'') an individual threshold value for a half defined as product of p and m, The above static parameters are ascertained, i.e. prepared by the central control CC by sequential starting of the communication system and stored for decisions to be taken at a later date. As already mentioned the static input parameters for a line trunk unit half are specifically created. Since the decisions to be made are only necessary if first and second terminal hardware modules ABG1, A.BG2 are installed together in a line trunk unit LTU1,-,LTUn, the static input parameters must only be kept for such line trunk units, i.e. their halves.

W_ In the previous embodiment it should follow that a telecommunications connection via a connection interface device AE on a second terminal hardware module A.BG2 should be made, which is allocated to the first half L' of a line trunk unit. Since the two pairs M', W' of multiplex channels for a connection of a time slot are at the disposal of the second terminal hardware module ABG2, the central control CC will decide from which pair of multiplex channels a time slot will be chosen.

For this purpose the dynamic input parameter f W) will be determined:

f (L') the number of as yet unoccupied time slots in the pair of multiplex channels allocated to the second terminal hardware module ABG2, that is to say its own half.

This number f(L') is compared with the determined threshold value TW) for the same half L' - namely for the half L, allocated to the second terminal hardware module A.BG2. If the number f(L') of as yet unoccupied time slots is larger than the threshold value T(L'), then a time slot in which the pair M' of multiplex channels is allocated to the second terminal hardware module A-BG2 will be sought. In these cases the second terminal hardware module ABG2 behaves as a first terminal hardware module ABG1. In the case of other comparison results a further dynamic input parameter f(L'') is determined:

f W ') the number of currently unoccupied time slots in the pair of multiplex channels not allocated to terminal hardware module ABG2.

After the preparation of b (L') = p (L') x f (L') b (L'') = p W') x f (L') as half-specific demand factors for both halves of the line trunk unit LTU1 a comparison is carried out to ascertain whether the difference between f (L') and b(L') is greater than or equal to the di f f erence between f W 1) and b W 1). In positive cases, i.e. when the difference relating to the half L' is greater, a time slot in which the multiplex channels M' belonging to the half L' are, must be sought, otherwise a time slot in which the multiplex channels W' belonging to the half W' are, must be sought. After reaching a decision the central control CC transmits to the concerned second terminal hardware module ABG2 control information concerning which of the pairs of available multiplex channels M' M, ' a time slot must be sought in.

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Claims

Claims ez 1. Process for the allocation of multiplex channels in a

communication system having a number of time slots, for the transmission of telecommunications voice and data signals between connection interface devices and an interface, wherein first connection interface devices have available only a first pair of multiplex channels and second connection interface devices have available in addition at least one further pair of multiplex channels for allocation, and wherein for making a telecommunications connection via the second connection interface device, a central control (CC) will select one of the available pairs of multiplex channels of the second connection interface devices in dependence upon the following, which relate to a pair of multiplex channels:

a number (e) of first connection interface devices (AE(ABG1)), - a number (g) of first and second connection interface devices, a number (m) of time slots available in the concerned pair of multiplex channels, a number (f) of free time slots in the concerned pair of multiplex channels, wherein the quotient of number (e) and number (g) forms a utilisation factor (p), the product of utilisation factor (p) and number (m) forms a threshold value (T), and the product of utilisation factor (p) and the number regard case of a the said otherwise number (f (f) form a demand factor (b), and wherein with to the first pair of multiplex channels, in the number (f) greater than threshold value (T), first pair will be selected for allocation, the pair for which the difference between and demand factor (b) is the largest will be rl selected.
2. Process according to claim 1 wherein the connection interface devices comprise a line trunk unit and the first connection interface devices comprise a first half of the line trunk unit and the second connection interface devices comprise the second half of the line trunk unit.
3. A communication system comprising first connection interface devices and second connection interface devices and two pairs of multiplex channels having multiple time slots, wherein the first connection interface devices are connected to a first pair of the channels and the second connection interface devices are connected to both pairs of the channels and wherein control means is provided which is adapted to select the multiplex channels to be used by said second connection interface devices in accordance with a rule requiring it to consider the current utilisation of the system and to leave the first devices still usable at the highest possible capacity level.
4. A process for the allocation of multiplex channels in a communication system substantially as hereinbefore described with reference to the accompanying drawings.