Method for controlling data circuits

The Invention relates to a method for controlling data connections according to the preamble of claim 1.

Out the ever converging communication and information technology are networks, such as a "Local Area Network" LAN, with a variety of data transmission Enriched known stations, the transmission of the data by wire, ie the stations communicating conduits is carried out, while in a accordance with the IEEE 820.11 Standard trained local area network ( "Wireless Local Area Network", WLAN), the transmission wireless, ie a spark gap, is realized with a Wireless also a hybrid network of over Line or radio link connected stations is permitted.

On to these networks connected stations are mostly Applications implemented or partly firmly installed, the various services include and - depending on the type of station - from can vary station to station. Thus has the converging of networks of information and Communications technology to the development of networks and services of the transfer "non-time" data as in a file transfer, or the transfer incurred by emails routed to networks with "time-sensitive" data, such as the transfer voice data ( "Voice over IP ", VoIP) Video conferencing, and streaming media, the latter services among other reasons are as time-critical because delays and / or loss of data from a user directly detected, ie belongs or be seen, and this is why possible real-time transmission the associated Data is required.

In a WLAN is generally given both time-critical and non-time Data is transmitted. In an exemplary, a simulation underlying, WLAN Arrangement as in <figref idrefs="S12">1</figref> illustrated is configured with a, as a PC, workstation or server, first station SERV1 and second station SERV2, one, as a mobile terminal for voice communication well-designed, third station PP and, as for the representation configured of video data, the fourth station VS1 and fifth station VS2, which-providing by a radio coverage area Station ( "Wireless Access Point ") WAP over radio combine to form a network, for example, in a simulation of the Application of force at the time IEEE 802.11 standards, which in <figref idrefs="S14">4a</figref> and <figref idrefs="S14">4b</figref> Data volume represented TCP1, TCP2, UDP VIDEO1, VIDEO2 UDP, UDP and UDP VOICE1 VOICE2 to observe.

The Simulation results in accordance with the applicable IEEE 802.11 in <figref idrefs="S14">4</figref> shows, that for data transfer to disposal bandwidth by the number of active services - and thus more r transmissions - decreases as a result, for a the (real) time-critical application video stream required constant not guaranteed data rate is, where also still data packets are lost. In contrast, for single uncritical file transfers ftp1 .. FTP2 even up to 14 Mb / s possible.

Out Therefore, a so-called quality of service has been introduced in the standard IEEE802.11e. Under quality of service ( "Quality of Service" QoS) refers to all procedures that affect the flow of data in LANs and WANs so, that the service arrives at a specified quality at the receiver. to implement are some approaches been developed, such as the prioritization of data traffic. The approach of prioritization provides that time-critical services, such as video streaming, a higher priority is allocated, following a non-time, the prioritization, Data packets belonging to services with lower priority, in principle, with transmitted delayed a predetermined delay time by prioritizing be so for Data packets belonging to services with higher priority, a higher Data rate is achieved.

The the object underlying the invention is to provide a method, that the loss of real-time critical transfer packages towards the echtzeitunkritischen transmission packets reduced within a station of a wireless telecommunication system.

These Object, starting from the preamble of the patent claim 1 method defined by the characterizing part of claim dissolved 1 stated features.

At the The method according to the invention for controlling data connections for transmitting data on different Applications associated data connections in a local area network with at least two data transmission designed stations, to transfer to data packets segmented data to a data packet at least a first transmission protocol is assigned, be in the presence of at least one alternative second transmission protocol, the transmission timings the data packets in dependence the associated transfer protocol.

3

By The method of the invention can a local area network flexibly to the existence of several to choose from standing transfer protocols react. With this degree of freedom, it becomes possible the Advantages and disadvantages of transfer protocols to level, so that the effectiveness and resource utilization of the local network can be increased.

Preferably given that the determination of the transmission timings due to a first prioritization so that the transmission protocols, different priorities be assigned, so the protocols according to at least one of their characteristics may be weighted and algorithms for controlling the be able to complete this Properties within the network at advantageous times bring.

alternative or additional given that the determination of the transmission timings due to a second prioritization such that the data packets according to their Allocation be prioritized to applications. This is the Compliance of the applications, where the same transmission protocol is assigned, required different QoS requirements allows. In addition, a further level of setting the network properties is realized, the one more adapted flow control allowed.

Especially advantageously, the novel process unfolds when a first transmission protocol according to a connection-oriented, especially the TCP, the transport protocol and a second transmission protocol according to a connectionless, particularly the UDP transport protocol works, wherein preferably the first transmission protocol a lower priority than is the second protocol assignable. This prevents packets of the connectionless transmission protocol by the connection-oriented transmission protocol associated algorithms, the data throughput on a transmission medium to saturation increase, get lost. Such losses would be mainly in the connectionless transmission protocols noticeable since their loss can not be detected, that there is no repetition of the package. By contrast, losses packages according to connection-oriented transmission method be detected and thus resent. As often connectionless transmission protocols for the data transmission be used by video and voice applications, it would here to increasingly disturbing interruptions. The inventive method, however, the packets of the connection-oriented transmission protocol in a another queue that station managed as packages the connectionless transmission protocol, so that the algorithms of the connection-oriented transport protocols While activity may continue advantageous but not at the expense of data transmission according to the connectionless transmission protocols.

Preferably does the local area network as a "LAN" in particular as a wireless local area network "WLAN" in accordance with the IEEE 802.11 standard and its derivatives, so that the common applications Text, video and voice transmission can be applied.

A centralized definition has the advantage that the method only be implemented in one or a few instances of the local network must while a remote controller has the advantage, that the method implement stations with little effort and without changes existing networks, can be incorporated into the same.

Preferably is carried out the determination, in particular in the remote controller, based on information in an IP priority field so that information about the Transmission protocol used can be evaluated locally at the stations.

More Details and advantages of the invention will be the basis of a in <figref idrefs="S12">1</figref> to <figref idrefs="S12">2</figref>. <figref idrefs="S13">3a</figref>. <figref idrefs="S13">3b</figref>. <figref idrefs="S14">4a</figref> and <figref idrefs="S14">4b</figref> shown view detail explained. Of shows

<figref idrefs="S12">1</figref> the simulation underlying WLAN arrangement

<figref idrefs="S12">2</figref> Representation of the behavior the TCP algorithm

<figref idrefs="S13">3</figref> embodying a schematic illustration of a representation of a procedure according to the invention

<figref idrefs="S14">4a</figref> simulation results for a in <figref idrefs="S12">1</figref> and <figref idrefs="S14">4b</figref> illustrated arrangement according to the prior Technology (IEEE 802.11)

<figref idrefs="S15">5a</figref> simulation results for a in <figref idrefs="S12">1</figref> and <figref idrefs="S15">5b</figref> arrangement illustrated by the inventive process

In of the <figref idrefs="S12">2</figref> is a data throughput shown as in accordance with the TCP / IP Algorithm results. It becomes evident that the algorithm throughput (Throughput) increased until an increase not longer possible is.

These saturation is now bearing characterizedbar that data packets are lost, ie there is no confirmation (ACK) signal back.

This is detected, then the throughput is somewhat reduced. Once no more ACK signals are lost, the data rate is increased again, lost to again data packets. This creates a dynamic Balance with other data streams, resulting in a maximum data rate results.

This However, the algorithm also causes other streams also lose packets. If those data streams also the transmission protocol use TCP / IP, this effect has no permanent loss of Packages the result as these unacknowledged packets as lost are detected and sent again.

is If the competing data stream, however, for example, a UDP stream as the preferably for voice and video data Case, this has fatal consequences. The data packets are permanently lost and lead to poor transmission behavior. A high quality of service Quality of Service (QoS) can not be guaranteed.

at the in <figref idrefs="S13">3</figref> schematically Illustrated embodiment, of the inventive method is therefore a system which transmits also data streams according to the UDP protocol, takes into account, that the UDP protocol no dynamic increase in throughput to Limit includes. For this purpose, the mentioned problem is according to the invention by a prioritization of the UDP protocol solved.

As can be seen in the diagram, obtained UDP data packets, the transmitted in accordance with UDP protocol should be higher priority in the queue of the data to be sent packets, while data packets TCP / IP, in accordance with TCP / IP Protocol function received in comparison, lower priority.

The in the queues of the individual stations TERMINAL_1..TERMINAL_N thus divided data packets arrive then, accompanied by additional Access control method to the transmission medium WIRELESS OR WIRED MEDIUM.

Thereby it is achieved that by means of TCP / IP - data streams which UDP data streams (streams) not bothered are, with the TCP / IP -Streams among themselves behave like before.

The Result example undisturbed telephone call over WLAN, and undisturbed Video enjoyment while at the same time on the same or another terminal on the Internet can be surfed.

in this connection it is sufficient to achieve high-quality transfers also from the data packets that are sent by the UDP protocol only prioritize in case of conflict.

Independently of it is due to the invention in any case no longer necessary, distinguished by applications. Alternatively or additionally, If the decision locally basis of information on the Protocol in the IP Priority Field can take place.

On Another advantage of the method described is the fact that only two different queues for data processing required (TCP / IP and UDP) and not four as the current draft standard IEEE 802.11 E is recommended. this leads to to a reduction of complexity in the terminal, and thus a cost advantage.

This is apparent when one first based on <figref idrefs="S14">4</figref> and <figref idrefs="S14">4b</figref> simulation results a current WLAN network considered.

To Evident are UDP streams, the designated UDP_VIDEO1 and UDP_VIDEO2 are; these are the competitive equilibrium TCP / IP streams, for example, with TCP1 and TCP2, affected drawn so that UDP data packets are lost. This leads to a bad behavior regarding Quality of Service for UDP-use services. The deleted TCP / IP Packages, however, are recognized by the protocol and re-sent.

Out the illustration in <figref idrefs="S14">4b</figref> becomes clearly, that even when the delay times the quality of the UDP streams decreases, as in the underlying simulation by the prior art known Wi-Fi network values ​​of up to about 35 ms occur.

On the other hand is the result of a simulation of a method of the invention -use Wi-Fi network, which in the <figref idrefs="S15">5a</figref> is shown and the throughput shows, shows that by prioritizing the UDP streams no more data packets are lost. The through the TCP / IP algorithm caused equilibrium only acts between the TCP / IP streams. This is the Quality of Service for-use the UDP protocol Applications such as voice (voice) and video excellent.

The Representation of the resulting delay times (latency) as a result of the simulation in <figref idrefs="S15">5b</figref> supports this Conclusion as to, is seen that also the delay times for the accept UDP streams excellent values. This is because, that the values ​​despite intensive TCP / IP traffic in the inventive method incipient wireless network are far below of about 10 ms.