Method and system for establishing communication relations

Translation of description of equivalent WO 2007137921 A2

p0001description

p0002Method and arrangement for establishing communication relations

p0003The invention relates to a method and an arrangement for establishing communication relations

p0004In current communication networks are desired by users increasingly higher data transfer rates. Transmission method, the high transmission rates can also provide in the subscriber access networks (Access Networks) in a communication network, for example, methods which operate according to the xDSL methods are. can transfer methods Using these Uber- the operators of communications networks to offer their customers and broadband connections to the Internet, for example, by means of which the participants can use a number of applications in an increasingly easier and faster. An example of such a thus-intensive application, are needed for the high transmission rates, is about the transmission of real-time relevant multimedia files.

p0005In particular, the possibility zukunftig example GaN pendent television programs increasingly packet-oriented communication networks such as an IP network (IP "Internet Protocol"), transferred. This service is available as part of the so-called "Triple-Plays", which means that three - originally separate - data services (telephone, Internet, TV) are transmitted over the same communication network.

p0006Here are usually transmitted in so-called "Streams" u- at Fernsehubertragungen over an IP network ( "IP TV") the information. This means that a central server, the television programs in a durchgangigen flow of data translated (the programs are "streamed") and distributes this data to individual subscribers river. The data flow is in the frame received zuruckgewandelt and then displayed on a screen of such a distribution service of the individual participants.

p0007However, to this type of Fernsehubertragung to offer successful, it is important to note that the users or the customers in such a streaming method at least the same quality of TV pictures is made available, as in current television systems (cable, satellites lit, antenna) is the case.

p0008This means in particular that on the one hand, for example, sufficient image quality is achieved. Especially with Vi deo transmissions to transmission errors to beat in easily identifiable and therefore extremely disturbing errors in the

p0009Image representation from. So the picture may appear blurred, for example, or there occur so-called block error, ie individual parts or blocks of the image are displayed incorrectly.

p0010On the other hand must be, however, also ensured for a successful offering of IP-TV that other services or features that are used to transmission networks, participants of conventional television, are also available in IP-TV. One of these properties is the smallest possible switching time when switching between two television programs.

p0011While this is common in conventional TV networks since closing the participant applied in these networks all receivable programs simultaneously on arrival, it behaves in IP-based (or Ethernet) networks differently, in such networks are always only the required programs the connection to a subscriber. Basically shares a participant in an IP network with a central server that he might receive (a particular television program) a particular stream, ie the subscriber makes a request for a Communication link with this server. Then, the server initiates the appropriate stream to the subscriber on. In a switchover, which corresponds to a change of the stream, this switch must therefore only by means of various protocols the server informed and finally from the server (or two servers, if both streams originate from different servers) are carried out. At every switch of the television program thus a new stream has to be requested and created (or a new communication link to be received), a process which is more complicated and, therefore, needed more time than the switching in conventional TV networks.

p0012In current IP networks distributing a stream is achieved in one or more participants by means of so-called multi-point connections. Here, a data stream from a starting point or transmitter (for example a central server within the IP network) are received simultaneously to multiple receivers or subscribers. This is a "point-to-multipoint" connection or a so-called "multicast" method or multicast transmission.

p0013Multicast transmissions are currently controlled mostly by the "Internet Group Management Protocol" (IGMP). The IGMP is based on the Internet Protocol, enabling group communication. In a multicast transmission ( "multicasting") individual IP packets can be distributed under an IP address to several stations (to a group of sta- tions). To reduce the emerging amount of data this possible, the IGMP provides the ability to dynamically distribute groups. Individual participants or connections are thus allocated to specific groups with a specific offer. The administration of these groups will not in the transmitting station instead, but for example, in individual network nodes or in the routers on the way to receiver. But in the routers information is stored about chert, at which outgoing interface is a station or a port to be forwarded to the special multicast IP packets. In IGMP functions are implemented, with which, for example, the router communicate among themselves and with those stations can report a router that the corresponding subscriber wishes to receive certain multicast IP packets.

p0014At such managed multipoint connections thus is the transmitter usually not known what or even how many

p0015Participants will receive its IP packets. From station according IGMP only a single data packet to the appropriate parent router is shipped. Only within each router in the communication network, the IP packets are finally borrowed as needed multiplied. This is dependent on the number of devices connected to the routers stations that are to receive the corresponding IP packets. It must therefore support a multicast protocol such as IGMP all network nodes involved in the communication.

p0016In addition to numerous other protocol commands exist in multicast protocols, commands for requesting IP packets: By means of the so-called "j oin" command ( "JoinGroup") applied for example a participant's membership in a group, ie the subscriber demands include a particular stream or television, it is then to another receiver of the corresponding IP packets.

p0017If a participant escaping from a group in which he is currently a member desired, this can be done in accordance with the prior art by various methods. On the one hand this can timer-controlled manner (eg IGMP Version 1), on the other hand, a membership with an appropriate instruction but also be terminated directly (eg IGMP Version

p00182). For timer-controlled processes (such as the IGMPvI in which no stop command exists) are according to the protocol of a subscriber device sent at predetermined time intervals information on the respective parent node, indicating that the respective subscriber still wants to remain a member in said group. In the event that is received no such information at the network node within the predetermined period of time (when the timer expires in the node), the connection is terminated by the network node.

p0019In other multicast protocols for deliberately terminating a membership, there are certain commands (eg IGMPv2: "Leave Group"). Although in such cases, so it is possible to leave certain groups targeted, so work numerous current multicast implementations, such as, among other things about current set-top boxes, but also continue without this "leave" command. Even in such cases, the emergence of a group is then controlled by timer.

p0020Another way to terminate a membership in a group is the so-called "fast leave". It is an implicit termination of the membership. This means that in each case a new "j oin" request by a participant, so whenever the member requests such as a new television program that will be automatically terminated previ- ge membership in another group. This method can, however, only in rare cases, apply as a precondition for this is that the subscriber has only bear a single data stream or wants.

p0021A management of the individual participants and their group membership, so a management of multicast connections, can for example also be done centrally. For example, can be stored in a central administrative unit or in the DSLAM itself, which connected subscribers have subscribed to which IP data streams and which groups they belong. For example, a table displayed subscribed at the moment IP streams are stored address (MAC address) - are, in each local loop or for each "Media Access Control" sets. That is, even in the event that several Endge- are connected to rate a subscriber line, the Gruppenzugehorigkeit each terminal's logging is done using the unique for each device connected to an Ethernet MAC address UNIT. The information on the Gruppenzugehorigkeit can be recorded directly in the DSLAM for example the eavesdropping of IGMP ( "IGMP snooping").

p0022In most cases arises on leaving a group, or subscribing to a new group, particularly in the above-mentioned IP-TV applications following disadvantage: If a subscriber subscribes to a new group, as previously unsubscribed groups are not always automatically leaving. This leads to the fact that the new applications mostly not immediately have access to the bandwidth required, since a portion of the bandwidth is reserved even for the previous, no longer desired application.

p0023Especially for example, IP-TV this leads to an extension of the above-mentioned problem, the longer switch because the new selected program can only be displayed if the achieved for displaying the previous programs ford variable transmission resources were previously released.

p0024The object underlying the invention is therefore to improve, among other things, the provision of multimedia distribution services.

p0025This object is solved starting from a method according to the preamble of claim 1 by its characterizing features as well as an arrangement according to the preamble of claim 10 by its characterizing features. In the process of this invention is a method for establishing communication relations a Ubertragungsme- medium, wherein at least one communication session is already established via the transmission medium. The essential aspect of the process is that each requests for the construction of each of a communication relationship concerned information is collected and a function of at least two information collected at least one of at least terminated or maintain an already established communication relationship.

p0026The essential advantage of the inventive method is that individual communication relations can be degraded more quickly if they are no longer needed. Thereby bandwidth can be saved.

p0027the information collected can advantageously comprise times of the queries. In this case, the at least one already established communication session in response to a detected between at least two points in time past

p0028be terminated or maintain time - claims 2 and 3. As a result, for example, based on the length of the last between two requests time are joined GE in the way of the requested and the already established data streams.

p0029Further advantageous VERSIONS of the inventive method and an arrangement for establishing communication relations are described in the dependent claims.

p0030In the following the invention with the help of the attached drawings will be explained in more detail.

p0031In which:

p0032Figure 1 is a block diagram of a schematic representation of a subscriber access network, Figure 2 shows the time course of the bandwidth requirement of several IP data streams at the subscriber, and

p0033Figure 3 is a flow diagram of an exemplary sequence of the method according to the invention.

p0034Fig.l shows an example of a schematic structure of a subscriber access network of a current communications network. Three participants TNL, TN2 and TN3 are connected via a respective subscriber line DSLL, ADSL2 or DSL3 with a first exchange-end node, a so-called "digital subscriber line access multiplexer" (DSLAM). This DSLAM aggregates data from the connected devices together ( "multiplexing") and sends the collected data to the connected communication network. In addition, the DSLAM distributed as the data that are transmitted in the opposite direction, that is derived from the parent network, to the corresponding subscriber. On the network side of the DSLAM to a "Aggregation Network" (AGN) (1 in Fig. Not shown) is connected, which has the task more connected to this network DSLAMs finally to the main network (in Fig. 1, this is for example an IP network ) connect to.

p0035FIG. 2 illustrates an invention of the underlying problem using a schematic graphical representation of several IP data streams. In FIG. 2 is a distribution of three applied to a local loop data streams (streaml, stream2, stream3) over time (horizontal profile) shown graphically. The height of the individual data streams represents the bandwidth required by the respective data streams. In addition, a maximum time available for the corresponding subscriber tape is shown in Fig. 2 wide (B_Max) Located. At the time to be at the terminal under consideration (eg TNL from Fig. 1) two IP data streams (streaml, stream2) to. TNL has therefore subscribed currently two groups, or TNL is currently divided into two groups Member. It may be at streaml to any multicast application while it is assumed in this example for stream2 that this is television data in this stream (stream2). There are thus in this example, at time t₀ over the same local loop (DSLL) at the same local loop (TNL) received two multicast applications, wherein a stream2

p0036IP-TV application represents. Streamliner and stream2 need here together, not all related to the local loop available bandwidth.

p0037Participants TNL subscribed at the time ti a further, third multicast group (stream3), that is, sent to the DSLAM subscriber TNL a "j oin" request for group 3, in this case, another television program. Subsequently, the more this television program transmitted data is ström to subscriber line DSLL of participants TNL applied.

p0038As seen in Fig. 2, then lie on local loop DSLL of participants TNL same three multimetal ticast data streams (streaml, stream2, stream3) to. However, since the available bandwidth on DSLL is less than the bandwidth required for all three streams, the newly subscribed television (stream3) of participants TNL is not yet transmitted completely or in sufficient quality and are thus displayed undisturbed at participants TNL.

p0039This is only from that time (t₂) Possible, to the data stream 2 (stream2) is terminated to the subscriber line DSLL. As explained in the introduction, however, data stream 2 (stream2) be terminated only after expiration of a timer when using, for example IGMPvI. Also, in this example stream2 immediately when applying implicitly terminated by stream3 because already several multimetal ticast streams bear (streaml and stream2). Thus not determined which of the two adjacent streams should be terminated, so it is not a "fast leave" possible. For such cases where the previous data stream (stream2) so only after a certain period of time (At = t₂ - Ti) can be terminated, and also for those cases where for some reason the "Leave Group" command deliberately can not be used or should, thus results adversely prolonged, by users mostly annoying perceived switching time (At).

p0040This is, as described below, significantly reduced by the inventive method. The exemplary sequence of the method is in this case illustrated with the aid of the flowchart in FIG. 3.

p0041In the method according to the invention is examined in a first section, for example, if it is a new guest, so current, sent by the subscriber request for a stream ( "JoinGroup" command) to a quick conversion or switching through television programs (so-called "Zapping") concerns. To determine this, the time between two j oin commands measured according to the invention (S301). If the value measured under a predetermined threshold, for example 2 seconds, is recognized on zapping. It is therefore assumed in the present invention in such a case, the fact that in many successive and received at short intervals j oin commands the participants numerous television programs sequentially through switches. If it is detected at such a zapping, the membership of the corresponding subscriber in the previously subscribed group is terminated directly (S302) according to the invention. It will not be serviced until the expiration of a timer. Furthermore, the newly subscribed group is entered in step S303 in the management table. Optionally can be made in the Gruppenzugehorigkeiten to step S303 even a review of the changes made (in steps S302 and S303) previously. For this purpose, it is checked whether the group you just deleted is not yet still desired by the subscriber, ie, whether the assumption that it is zapping, was wrong. For this purpose, triggered for example, directly from the DSLAM, a so-called "membership query" only for the corresponding group and only to the relevant subscriber port sent (S304). This requires as a counter response confirmation (S305), if the corresponding group is still desired. Remains from this response, as was the assumption that it is zapping, right (S306). However reaches the DSLAM a riposte ( "Membership Report"), so it can be concluded that, contrary to expectations, no zapping is present (S307) and the corresponding group can be immediately re-registered in the management table (S308). This additional interaction adjusted a possible error occurs immediately, an error has been corrected are so far ahead of the next routinely sent by the multicast router membership query.

p0042If it is determined in step S301 that it is the current request probably not for a new group to zapping, ie, the time between two requests above the predetermined threshold, so accordance with the invention optionally further steps can be taken to shorten the switching time. For example, can be checked whether the new subscription request from the same MAC address is derived as the preceding (S309). If this is the case here - despite the slightly longer period of time between requests - be assumed that it is requests for IP TV data streams at the requests. Thus, it can also, for example, decided to directly to "zapping" and then tried to reach by direct Loschen the previous group membership nearly a comparison zogerungsfreies switching. However, it would be suitable in such a case, the done assuming ensure for convenience to check first. According to the flowchart in FIG. 3 is to the present invention, for example by means of a membership query sent directly after asking if the foregoing, any group to be deleted is still needed (S310). If this is not the case, so no membership report is expected to be received in step S311, the previous membership is terminated (S312) and the current group newly registered (S313). If the previous group but still needed so true in step S311, a Membership Report a, then the newly subscribed group additionally included in the management table (S314), the subscriber subscribes therefore a farther Stream. It will set up a new, additional communication link.

p0043If it is determined in step S309 in the flowchart of FIG. 3, that the last two questions are not from the same MAC address, no assumption can be made with respect to the groups to be deleted. In this case, however, from the DSLAM for example, a "general membership query", ie a membership query to all connected devices, initiated (S315). This corresponds to a membership query for each group. can therefore This central general membership query then dependent on the responses occurring all group entries are updated within the management table (S316). Even by such a path directly after a request General Membership Query switching time can be saved. This can according to the invention, of course, not be carried out only on the date shown in this embodiment, but at any time, particularly in cases in which can not be clearly determined, whether it is at a request to zapping or not.

p0044It should also be noted that according to the invention for detecting zapping not limited to the time period between two directly successive inquiries must be determined. It can be inventively also checks between several consecutive requests elapsed time, In addition, the time between each arrival of certain subscriber terminals or subscriber ports and also individual MAC addresses can ask respect be considered. In the management table, for example, all requests are in such a case by the individual addresses stored and the inventive method is applied separately to each subscriber or each MAC address.