FI107216B - Signaling in a telecommunications system - Google Patents

Description

107216

Signaling in a telecommunications system Signallering i et telekoxnmunikationssystem

Field of the Invention 5

The present invention relates to signaling in a telecommunications system, and in particular, though not necessarily, to the transmission of signaling data for voice or data calls.

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BACKGROUND OF THE INVENTION In the telecommunications system, 15 signaling equipment and signaling channels are required for communication between system units or nodes. More specifically, this inter-node signaling tells the node what to do to connect or disconnect a voice or data connection. "circuit switched" connections. Modern telecommunications systems 20 are now commonly used for common channel signaling (Common

Channel Signaling (CCS), where the signaling information is transmitted on one or more separate signaling channels, separate from the channels used to transmit the actual user information (e.g., audio or data). An important feature of CCS i · · 25 is that · · · * can be supported by the same signaling system. \ various existing telecommunication protocols • services such as the Public Switched Telephone Network (PSTN), the Integrated Services Digital Network, 30 ISDN), and Public Land: * · *: Mobile Networks (PLMN), as well as proposed future protocols such as B-ISDN, which greatly • *. contributes to the interoperability of networks supporting different protocols.

Known as Signaling System Number 7 (35 2 107216 SS7), CCS is currently the most widely used, as defined in ITU-T (International Telecommunications Union-Technical) recommendations, starting with recommendation Q.700. SS7 is a 5 packet switched data transmission system which adopts a single time slot frame per time division multiple access transmission mode E.l or T.l (other time slots are free for user information). Individual signaling message packets (10 datagrams) associated with corresponding individual calls.

Because a relatively small amount of signaling information is associated with a single call, a single SS7 channel is capable of handling signaling between all two nodes (called "signaling points") of thousands of calls. 15 Note that the route taken by the signaling message on the SS7 network may be the same as that on which the associated call is connected, or it may be different.

SS7 (along with other CCS systems) is capable of supporting a number of different telecommunications protocols (e.g., PSTN, ISDN, PLMN), as already noted.

In terms of signal processing, SS7 consists of a Message Transfer Part (MTP) that is involved in the physical: ': 25 transfer of signaling information in the signaling network, i.e., message formatting, error detection; * ·. ♦ and rectification, etc., and user parts. User parts) and application parts that allow; · · Sending signals from multiple "users" (i.e., ISDN User Part, Telephony User 30 Part, etc.) in the same signaling network.

SS7 uses addresses known as Point Codes to signaling information paths. 35 through the "field of view" of the telecommunications network, where the field of view is typically the network itself, along with the interfaces between this network and the networks controlled by "foreign", "external" network operators. The point identifier is placed in the header of the packet and is viewed by the packet upon receipt of the packet 5 to determine the next transmission interval along the route to the destination of the packet.

In the SS7 network, any change in the allocation of the point identifier, or 10 charges, within the visibility range requires the operator to update the point code database (or routing table) in each SP of the network. However, this significantly increases overall network maintenance. Due to its special nature, SS7 is generally expensive to install and operate (both hardware and software), which is a significant barrier, especially for novice network operators. Further, because SS7 allocates bandwidth in TDMA frames of E.I / T.I transfer protocols (one time slot per frame), the actual user data will have less bandwidth. A further disadvantage of traditional signaling architectures is the limited interoperability of SS7 networks due to the special nature of physical MTP layers.

t * *: * · *: 25 SUMMARY OF THE PRESENT INVENTION

The object of the present invention is to eliminate or at least alleviate the above disadvantages of existing telecommunications signaling systems.

In accordance with a first aspect of the present invention, an apparatus for transmitting signaling information between signaling transfer points, between signaling points. "* · Or between a combination of both in an SS7-. 35 signaling network comprising : · '·: A first SS7 / IP gateway device connected to the first 4107216 signaling point or signaling transfer point and also an Internet Protocol (IP) network, and a second SS7 / IP gateway device connected to the second 5 signaling point or signaling point and and to said IP network, wherein the first and second SS7 / IP gateway devices are arranged to receive SS7 signaling information from said associated signaling points or character -10 output transfer points and convert that information into an appropriate format for transmission on the IP network and a is a reverse conversion of signaling information received from an IP network.

In certain embodiments of the present invention, hardware gateway devices are standalone devices. In other embodiments, however, the gateway devices may be integrated at a signaling point or a signaling transfer point.

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The gateway nodes can be connected to an IP network through respective Internet Access Server (IAS). Alternatively, the gateway nodes can be connected directly to the IP network.

.V. 25 • · ·

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The gateway nodes are connected to their respective signaling points / signaling transfer points preferably via PCM or •. * TDMA connections, e.g., E.l (2 Mbps, 32 channels) or T.l * y * (1.5 Mbps, 24 channels).

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The gateway nodes are connected to the corresponding IASs by preferential • · ·: .ί packet switched data connections, e.g.

: Using Ethernet or ATM.

The gateway devices may be provided with conversion or conversion means for conversion between the ISUP communication mode and the SIP communication mode 5 107216, the conversion between the H.323 communication mode and the SS7 call set-up mode, between the ISUP and the network access server control protocol, e.g. For conversion between an ISUP and an IP-5 voice control protocol, e.g. Q767 ++.

The gateway devices may be provided with an interface for tunneling the messages of the SS7 application section through IP. For example, the gateway gateway 10 may have one of the following protocol stacks arranged on the SS7 and IP side: SS7 side IP side 15

ISUP / MTP ISUP / IP

MAP / TCAP / MTP MAP / TCAP / IP INAP / TCAP / MTP INAP / TCAP / IP

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Gateway nodes may be adapted to determine the IP routing address of a received message or message set based on one or more of: Signaling Link Selection + Service Information Octet, Subsystem number, and Global Title Translation (interpretation of the general heading • · *.).

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Embodiments of the present invention allow the information transmitted through the V * 30 system to be separated into call information and signaling information. Utilizing an IP-based network to transmit signaling information frees up::: system capacity to use for call information.

. In addition, the use of an IP network reduces the need for traditional signaling infrastructure (although this may still be · in some cases available). IP-based networks offer • · 6 107216 greater flexibility (eg network routers have self-updating routing tables) and lower operating *, maintenance and maintenance costs compared to traditional telecommunications signaling networks.

Advantageously, the signaling data to be transferred over the IP network consists of signaling information relating to call setup and call termination of the first transmission network of the telecommunications system. Signaling information related to call billing may also be transferred over the IP network.

According to another aspect of the present invention, there is provided a method of transmitting signaling information between signaling points in a telecommunications network and / or signaling transfer points comprising: transmitting SS7 signaling information from a first signaling point / signaling transfer point to a first SS7 / 1P gateway; converting the signaling information in the first one-to-one gateway to a format suitable for transmission over an IP network; transferring formatted data from the first gateway to the second SS7 / IP gateway over an IP network; . 25 receiving the formatted data in another connection.

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in the corridor and recover the original signaling information • · *. *. taking them; and transmitting the recovered signaling information to · · «•« t *. * to another signaling point / signaling transfer point.

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According to a third aspect of the present invention, there is provided a method of transmitting voice information::: and other user information between an end user pair, the first end user having a circuit-switched interface to a telecommunication network and the second end user having a packet-switched interface to the IP network. comprising 7107216 exchange of signaling information between a telecommunication network and an IP network via a gateway device adapted to convert the signaling information between the IP voice transmission mode and the SS7 mode.

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Brief Description of the Drawings

In order to better understand the present invention and to see how it may be implemented, the following 10 are exemplary of the accompanying drawings in which:

Figure 1 is a diagram illustrating a telecommunications system consisting of two interconnected telecommunications networks;

Figure 2 is a functional representation of the architecture of the gateway device of the system of Figure 1;

Figure 3 is a diagram illustrating the SS7 protocol signal processing layers;

Figure 4 shows the processing layers in the gateway gateway node of the system of Figure 1; Figure 5 illustrates a signaling information stream relating to call setup and call termination in the system of Figure 1;

Figure 6 is a flowchart showing the signaling process used in the system of Figure 1.

'· 25 • «· • · ·.; *! Detailed Description of Certain Embodiments.

The telecommunications system in which the present invention may be used typically comprises one or more telecommunication networks interconnected. Telecommunication networks may utilize the same telecommunication protocol (eg ISDN, PSTN, PLMN) or they *; 'j'; may use different protocols. In addition, networks. may be subject to the same or different operator.

35 What they have in common, however, is that they use a * * SS7 signaling system to communicate signaling information between internal signaling points 8 107216.

Consider Figure 1, which shows a telecommunications system 5 consisting of only two telecommunications networks 1,2, in a very reduced form. Assume that each network 1,2 is an ISDN (Digital Multiservice Network). Each network consists of a plurality of telephone exchanges 3 connected to the trunk lines 4. Furthermore, the remote connection 5 establishes a link between the telephone exchanges 3 10 of the two networks 1,2.

To connect the call from the first subscriber telephone 6 (subscriber A) to the second subscriber telephone 7 (subscriber B) connected to the local exchanges of the respective networks, the system must allocate a communication channel between each of the four described exchanges 3 using long distance 4.5. Each communication channel is a circuit switched channel, that is, it consists of one busy time period on each successive handover 20 and such a network through which the call is routed is referred to herein as a "circuit switched network".

As already mentioned, the signaling exchange between the exchanges traditionally required for the formation of different circuit-switched channels is transmitted by SS7. In the system of Figure 1 · »· f1 2 · 1 ·, the SS7 network 8 is implemented in both: in the telecommunications network 1,2. Each of the SS7 networks 8 takes care of the signaling information between the signaling points (e.g. switches 3) i ♦ of the respective network. Signaling information may be routed directly between two signaling endpoints, or may be routed through Signaling Transfer Points (STP) 9 :.

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Note that although SS7 networks are depicted in ____: Figure 1, separate from circuit switching networks, SS7 networks · ·, 35 may use remote connections 4 for signaling data transfer, and that STPs 9 may be associated with corresponding 9107216 exchanges 3.

In each of the networks 1,2 there is a gateway device 10 which connects from SS7 network 8 to the IP network 11. In Figure 5 1, the gateway devices 10 are connected to the IP network 11 through respective Internet Access Server 12, although it should be noted can be implemented directly, without intervening Internet access servers 12.

10 It should be noted here that the term "IP network" is intended to include networks using the current de facto IP standard, as defined by the Internet Engineering Taskforce, 15 or future developments thereof (including TCP- or UDP protocol layers). The network 11 may be a closed network, i.e. an intranet network, under the control of the telecommunications network operator (s), or an open network accessible through the World Wide Web 20 (i.e., the Internet). In both cases, a number of important benefits are achieved by replacing the SS7 network with a substantial part of the IP network, with the reduction of signaling traffic and processing required above all; traditional telecommunication network and telecommunications; Replacement of 25 expensive specialized infrastructure with low cost, - * · flexible datacom infrastructure.

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In each of the networks 1.2, the gateway device 10 is connected ... 30 on the one hand to the Internet access server 12 and on the other to A »* ··· * ST7 of the SS7 network 9. Although the gateway device 10 may be connected to the SS7 network. for each STP 9, it is «··· advantageous that the connection be made to a subset of the 411 STPs 9 of the SS7 network 8 only, so that the signaling information transmitted between a particular STP 9 and 35 gateway devices 10 may require routing through one or more intermediate 10 107216 STPs 9. Figure 2 is a diagram illustrating a possible architecture of gateway gateway devices 10.

Note that the transmission of signaling information from 5 signaling points on one network 1,2 to a signaling point on another network via TCP / IP network 11 requires a protocol conversion on each gateway device 10. More specifically, it is necessary to process the signaling messages so that the physical structure of related error detection and debugging methods, etc. are applicable to the medium on which the message is subsequently transmitted.

Figure 3 shows the seven layers (or layers) of the SS7 protocol. These layers are not explained in detail here, but the reader is referred to ITU-T Recommendations starting with Recommendation Q.700 for reference. Suffice it to say here that layers 1-3 form a physical layer, a transmission layer and a network layer, while layers 4-7 consist of user parts and application parts that are generally network specific (especially TCAP provides event eligibility for services such as INAP, MAP, OMAP, etc. .) ... 25 Figure 4 shows the processing layers formed in gateway device 10 for converting signaling messages SS7-4 *] · /; protocol and TCP / IP protocol. On the network side of the SS7 interface, the SS7 protocol MTP is implemented, while on the TCP / IP side, the MTP is replaced by the TCP / IP protocol layers.

The signaling messages received from the 30 SS7 networks 8 by the gateway device 10 are thus processed by MTP to display the signaling information originally generated by the user component in the SS7 network SP.

... 35 In the gateway device 10, this information generated by the user part is transmitted by the MTP to the processing intermediate layer (referred to as 11 107216 by reference number 12). This layer 12 adds a header (9 bits) to each signaling message to indicate the number of bytes (octets) contained in the message. The processed messages are then transmitted to the TCP / IP protocol layers 5, where they are arranged through IAS 12 in a format to be transmitted on the TCP / IP network 11.

Similarly, when the gateway device 10 receives signaling information from IAS 12, the character-10 output information is processed in TCP / IP layers to retrieve the user-generated information including deletion of the message message header in intermediate layer 12 prior to transmitting the information to the MTP to prepare for transmission

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Note that Figure 4 shows the layer (s) of the user section (s) above the MTP and TCP / IP layers. However, this layer is not normally used in the gateway device unless the node is directly connected to the exchange 3 so that the signaling information can be transmitted directly from the user parts (e.g. TUP, ISUP, etc.) to the TCP / IP layers and vice versa.

:, i ,: It should also be noted that when signaling messages are routed: ': 25 on the SS7 network using SS7 point IDs, the messages are: 1 ·. · routed on the IP network using IP addresses. Gateway gateways may therefore include a database that converts • point codes into IP addresses using dynamic update if necessary.

Fig. 5 illustrates the flow of signaling information relating to call set-up and call termination '·· /' between two phones 6.7 in Figure 1, where signaling points are identified by the same symbol. 1 Figure 35 is a flowchart illustrating the signaling process described above.

12 107216

It will be apparent to one skilled in the art that changes may be made to the embodiments described above without departing from the scope of the present invention. For example, when a user's voice or data channel is described above as a circuit switched channel (E1 / T1), this channel may be wholly or partially a packet switched channel, e.g., when a call is initiated from a mobile phone or made to a mobile phone registered in 10 mobile networks. , which uses the proposed General Packet Radio Service, GSM Phase 2 +.

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Claims (11)

13 107216 Apparatus for transmitting signaling information in an SS7 signaling network between signaling transfer points, 5 signaling points, or a combination of both, characterized in that the apparatus comprises: a first SS7 / IP gateway device connected to a first signaling point or signaling transfer point 10 and also an Internet Protocol; and a second SS7 / IP gateway device connected to the second signaling point or signaling transfer point and also to said IP network, wherein the first and second SS7 / IP gateway devices are arranged to receive SS7 signaling data from said connected signaling points or signaling transfer points and format and perform 20 inverse transforms on the character output data received from the IP network. Apparatus according to claim 1, characterized in that the gateway devices are loose devices. : · '25 • · • · • *! Apparatus according to claim 1 or 2, characterized in that the gateway devices are integrated with corresponding signaling points or signaling transfer points. • · ·: 30 • · · A process according to any one of the preceding claims. hardware, characterized in that the gateway nodes are connected to the IP network via respective Internet Access Servers (IAS). :. Apparatus according to claim 4, characterized in that the gateway nodes are coupled to corresponding IASs by packet-switched data links. Apparatus according to any one of the preceding claims, characterized in that the gateway nodes are connected to respective signaling points / signaling transfer points by PCM or TDMA links. Apparatus according to any one of the preceding claims, characterized in that the gateway devices are provided with converter means for conversion between the following forms: the ISUP message transmission mode and the SIP message transmission mode; H.323 messaging mode and SS7 call setup mode; ISUP and Network Interface Server 15 protocol protocol, or ISUP and IP voice control protocol. Apparatus according to any one of the preceding claims, characterized in that the gateway devices 20 can be provided with an interface for tunneling the messages of the SS7 application section via IP. ,. ·. The apparatus according to any one of the preceding claims, characterized in that the gateway nodes are adaptable. : 25 to determine the received message or message sequence »· · • · IP routing address based on one or more of the following: · Signaling Link Selection + Service Information Octet • Subsystem number (subsystem number) ), and Global Title 30 Translation (interpretation of the general heading). • · · • · · · · · · 10. A method for transmitting signaling information between telecommunication, ···, tethering network signaling points and / or signaling transmission points, characterized in that the method comprises: 35 Sending SS7 signaling information from the first «« 15 107216 signaling point / signaling transfer point to the first SS7 / 1P gateway; converting signaling information in a first gateway to a format suitable for transmission over an IP network; transferring formatted data from the first gateway to the second SS7 / IP gateway over an IP network; receiving the formatted data at the second gateway and recovering the original signaling data therefrom; and transmitting the recovered signaling information to another signaling point / signaling transfer point. A method for communicating voice data and other user information between an end user pair, wherein the first end user has a circuit switched connection to the telecommunications network and the second end user has a packet switched connection to the IP network, characterized in that the method comprises gateway information exchange between the telecommunications network and the IP network. . via an arrangement configured to convert the signaling information between the IP-I voice transmission mode and the SS7 mode. I 1 1 I «i« • · «· · •« «·« «I * • i« i «i«. · • ♦ * • · · I «• • •« «• 44« * · «· I · * 44 <f 16 107216