WO2007110407A1

WO2007110407A1 - Method for transmitting data

Info

Publication number: WO2007110407A1
Application number: PCT/EP2007/052869
Authority: WO
Inventors: Matthias Kutschenreuter
Original assignee: Siemens Aktiengesellschaft
Priority date: 2006-03-28
Filing date: 2007-03-26
Publication date: 2007-10-04
Also published as: DE102006014356A1; EP1999904A1

Abstract

The method for transmitting data from a starting node in a network has the following steps: a metric value is ascertained for the starting node; at least one transmission parameter is determined using the metric value; the data are transmitted taking account of the transmission parameter.

Description

description

Method for transmitting data

The invention relates to a method for transmitting data as well as a network node and a network.

Certain data, when transmitted between network nodes of a network, requires compliance with a maximum delay time, ie, a maximum delay. An example of such data is VoIP (Voice over IP) transmissions, for example voice connections. In these, exceeding the maximum delay time may be more troublesome to a human user than a packet loss, ie a short absence of voice information. Other examples include data the transmission with a quality of service SUC ^¬ gen needs, called the so-called. "Conversation Class". This also includes, for example, video telephony data.

Data is usually subjected to a coding process for transmission. The coding method ensures that the data is brought into a form suitable for transmission, for example in the form of individual data packets which, for example, may have headers. Furthermore, the encoding method can be used to compress the data in order to reduce the bandwidth of the network required for transmission. The compression can be lossy or lossless. In ^¬ games for coding are the VoIP codecs G.7x, for example. G.711.1 or G.729.3, or the video codec MPEG-x, for example. MPEG-2 or MPEG-7. Furthermore, it is also possible that the coding method performs an encryption of the data, which should prevent unauthorized reading of the data. Furthermore, it is possible for the coding method to specify a transmission rate of data packets, ie a number of data packets to be sent per unit of time.

It is known for this purpose to select a coding method for the network nodes which guarantees that the maximum delay compliance of all network nodes. The application of this method results in a limitation of the ma ^¬ ximal possible simultaneous transmissions.

The object underlying the invention is to specify a ^method for transmitting data, a network node and a network, which increases the number of simultaneously possible transmissions.

This object is achieved by a method according to claim 1 ge ^¬ . Further solutions consist in a network node according to claim 7 and a network according to claim 10.

The method for transmitting data from a start node of a network comprises the steps of: determining a metric value for the start node; Determining at least one transmission parameter at ^¬ hand of the metric value;

Transmission of the data taking into account the transmission parameter.

The metric value is a value that relates at least to the starting node. For example. For example, the metric value may be a value that can be set for the start node, or a value that is determined for the start node at the beginning of a data transfer. When determining the metric value, one or more additional network nodes of the network can also be taken into account.

Preferably, the metric value for a path between the

Start node and the other network node can be determined. In this case, the metric value is preferably a measure of the quality of a path between the start node and the further network node. An example of the further network node is a gateway. The gateway can, for example, serve the forwarding of data from or into another network to which the start node does not belong. A transmission Para ^¬ meter is determined using the calculated metric value. This can be done, for example, by selecting a first value for the transmission parameter if the metric value is below a threshold value, while otherwise using a second value for the transmission parameter. Another possibility is to define various ^¬ dene areas for the metric value and set a value for the transmission parameters for each of the areas. The value for the transmission parameter is then used in the range of which the metric value lies.

The transmission parameters are properties of a coding method used. Examples include the type and strength of a compression, a transmission rate of data packets, the manner of encryption to be used or division of the data into data packets and the structure of the data packets.

A transmission in consideration of the transmission parameter here means that the parameter is used or maintained during the transmission, for example. For example, if the amount of compression is used as the transmission parameter, the data is compressed according to the amount of compression before transmission.

In an advantageous embodiment of the invention, a transmission rate of data packets is used as transmission parameter.

Preferably, the transmission parameter (s) together determine a coding method, in particular a codec.

In a further advantageous embodiment of the invention, the metric value is determined based on a number of intermediate nodes between the start node and the further network node, in particular the hop count. This has the part before ^¬ that the determination of the metric value is easy and less computationally intensive. Furthermore, the hop count changes not constantly, which, for example, allows storage of the metric value for multiple transmissions. ^¬ approximately possibilities Further preferred exporting exist in the alternative or additional use of the metrics ETT, ETX, or ELR. These have the advantage of being used, for example, for the routing of transmissions, ie for the determination of paths in the network. Characterized the determination of the metric value is simplified and a load of the network with Übertragun ^¬ gen reduced for determining the metric value.

In a further advantageous refinement and development of the invention the determination of the Übertragungspa ^¬ rameters is in addition based on a definable Verzögerungsma ^¬ ximalwertes. This delay maximum value can specify, for example, with which maximum delay (delay) the data may be transmitted. This gives rise to the advantage of being able to determine a specific quality that can be set by the delay, for example for VoIP transmissions, and to make it precisely adjustable. The network node comprises means for determining a metric value, a processing unit for determining at least one transmission parameter, and a transmitting means for Übertra ^¬ supply of the data and is designed such that the per ^¬ zessiereinheit determines the transmission parameters based on the metric value and the transmission device, the data among Be ^¬ consideration of the transmission ^parameter transmits. In a preferred embodiment, the transmission parameter is a transmission rate of data packets.

The network has at least one network node according to the invention. Preferably, the network is a multihop network.

Further details and advantages of the invention will be explained in more detail with reference to embodiments shown in the drawing. It shows

Figure 1 shows a network with a gateway. The network according to FIG. 1 contains a first to seventh network node Kl ... 7 and a gateway G, which are connected via WLAN to an adhoc network. The first to third network nodes Kl ... 3 are positioned so that they can directly reach the gateway G with a wireless data transmission. The fourth to sixth network node K4 ... 6 are so arranged to ^¬ that they can no longer directly but only the gateway G. reach via an intermediate node. In FIG. 1, the fourth network node K4 reaches the gateway G via the first network node K1 as an intermediate node, while the fifth and sixth network nodes K5, 6 reach the gateway G via the second network node K2 as an intermediate node. The seventh network node K7 is positioned so that it reaches the gateway G via the sixth network node K6 and thereby also via the second network node K2.

The following table provides a list of the network nodes K ^¬ ... 7 of the network and the respective number of hops, that is, the hop count between network nodes Kl ... 7 to the gateway G. In addition, the table indicates which delay ^¬ time (delay) during the transmission from the respective network node Kl ... 7 to the gateway G occurs.

Node Hop-Count Delay

Kl, 2, 3 1 3ms

K4, 5, 6 2 10ms

K7 3 20ms

In a first embodiment variant, each of the network nodes Kl ... 7 of the network selects the codec to be used in an upcoming VoIP transmission using the hop count. Since the network shown in FIG. 5 is an ad hoc network, its structure can change rapidly. The values for the hop count can change as well. Therefore, the hop count and thus the checked codec to be used at each ^¬ the new transmission. The following codecs should be available as an example:

Codec data packets / second Packetizing Delay G.711.1 100 10ms

G.711.2 50 20ms

In addition to the name of the codec, the table indicates the number of data packets sent in this codec every second. Furthermore, the so-called Packetizing Delay is specified, which occurs in the respective codec.

In addition to the hop count is a tarry ^¬ delay time used for the selection of the codec, which indicates the maximum delay for transmission of a packet to the gateway G. This should be 30ms in this example.

For the seventh network node K7, only 10ms remains of the delay time of 30ms after subtracting the delay of 20ms as the remaining allowable delay. Because of the packetizing delay, therefore, the seventh network node K7 must select the G.711.1 codec, resulting in the transmission of 100 packets per second.

For the first to sixth network node Kl ... 6, however, it is possible to select the G.711.2 codec with 50 packets per second and a packetizing delay of 20 ms. The delay and the packetizing delay do not yield more than 30ms here.

The average number of packets per second for a VoIP connection in the network is thus

3/7 * 1 * 50 + 3/7 * 2 * 50 + 1/7 * 3 * 100 = 107. In the method known from the prior art, the codec for all network nodes Kl ... 7 equal to select, the codec G.711.1 would have to be selected for all network nodes Kl ... 7. The durchschnittli ^¬ che number of packets per second and VoIP connection would be: 3/7 * 1 * 100 + 3/7 * 2 * 100 + 1/7 * 3 * 100 = 171st The reduced number of packets to be sent on average per second per VoIP connection increases the number of simultaneously possible VoIP connections in the network.

A second embodiment of the invention arises because ^¬ by that the routing metric ETX is used as a method for determining the metric value. Furthermore, the codec is not selected on the basis of the routing metric ETX, but the transmission rate of data packets is selected directly.

In the second embodiment, the following ranges for the routing metric ETX are used to the delegation ^¬ transmission rate of data packets to determine:

Metric value of data packets / second

0-2 40

2-5 50

5-10 75

> 10 100

For this embodiment, it should be assumed that the following metrics for the paths of the respective

Network node Kl. 7 to the gateway G yield:

Node metric value of first network node K1 1,1 second network node K2 2,5 third network node K3 2,0 fourth network node K4 2,2 fifth network node K5 4,0 sixth network node K6 7,2 seventh network node K7 10,5

According to the known from the prior art approach, all network nodes Kl ... 7 of the network would have a Übertra ^¬ transmission rate of 100 packets per second use. This would result, as in the first embodiment, an average rate of packets per VoIP connection and second from approx. 171st

When used in the second embodiment superiors hens, the first network node Kl would a Übertra ^¬ transmission rate of 40 packets per second using, as its metric value in the range from 0 to the second The second to fifth ^¬ te network node K2 ... 5 each use a transmission rate of 50 packets per second, the sixth network node K6 75 packets per second and the seventh network node K7 100

Packets per second. In this embodiment, the OF INVENTION ^¬ dung to an average rate of packets per VoIP connection and second results from 1/7 * 1 * 40 + 2/7 * 1 * 50 + 2/7 * 2 * 50 + 1/7 * 2 * 75 + 1/7 * 3 * 100 = 113. Due to the reduced number of packets to be sent on average per second per VoIP connection, the number of simultaneously possible VoIP connections in the network also increases in this variant.

Claims

claims

A method of transferring data from a start node of a network, comprising the steps of: determining a metric value for the start node;

Determining at least one transmission parameter at ^¬ hand of the metric value;

Transmission of the data taking into account the transmission parameter.

2. The method of claim 1, wherein the metric value for a path between the start node and another network node, in particular a gateway (G) is determined.

3. The method according to claim 1 or 2, wherein a transmission rate of data packets is used as a transmission parameter.

4. The method according to any one of the preceding claims, wherein the one or more transmission parameters together determine a coding method, in particular a codec.

5. The method according to any one of the preceding claims, wherein the metric value is determined based on a number of intermediate nodes between the start node and the other network node, in particular the hop count, and / or is used for He ^¬ mediation of the metric value ETT, ETX.

6. The method according to any one of the preceding claims, wherein the determination of the transmission parameter is additionally based on a definable delay maximum value.

7. Network node (Kl ... 7) with

Means for determining a metric value; a processing unit for determining at least one transmission parameter; a transmission device for transmitting the data, configured such that the processing unit transmits the transmission determined transmission parameters based on the metric value and the transmitting ^¬ device transmits the data taking into account the transmission parameter.

8. network node (Kl ... 7) according to claim 7, configured such that the transmission parameter is a transmission rate of data packets.

9. network node (Kl ... 7) according to claim 7 and at least one of claims 2 to 6.

10. Network with at least one network node (Kl ... 7) according to at least one of claims 7 to 9.

11. Network according to claim 10, configured as a multihop network.