DE10141553A1 - Transmitting data packets in radio communications system involves using individual data stream identifiers at transmitter end, characterizing packets with sequence number at receiver end - Google Patents

Abstract

The method involves providing data packets with identifiers for individual data streams at the transmitter and the data packets of the data stream are additionally characterized by a sequence number on the receiver side.

Description

3GPP / UMTS standardization currently uses procedures specified the efficient packet data transfers enable. Hybrid is an important technique here ARQ method. Hybrid ARQ processes derive their profit from that incorrect data packets in a memory in the receiver secured so that it can be combined with later transmissions can be. This can also result from faulty Data packets are benefited (in contrast to procedures in which faulty packets are discarded). The data bits that are in this memory must be backed up very quickly can be read out so that no unnecessary delays in of data transmission occur. Memory with this Property are usually very expensive.

• - Verschiedene Services mit verschiedensten QoS-Anforderungen gleichzeitig zu bedienen. Diese verschiedenen QoS-Anforderungen der Daten machen auch eine andere Abarbeitung der Daten im HARQ-Prozeß erforderlich. Diese Aufgabenstellung ist auf möglichst effiziente und einfache Weise zu lösen.
• - Weiter sollen die Daten, die beim Empfänger ankommen, wieder in eine korrekte Reihenfolge gebracht werden können. Der Empfänger wird die Datenpakete üblicherweise nicht in der korrekten Reihenfolge erhalten, da einzelne Datenpakete gestört sein können, die dann neu angefordert werden müssen, während andere, ursprünglich später gesendete Datenpakete sofort korrekt empfangen werden.
• - Möglichst effiziente Nutzung des oben angesprochenen sogenannten schnellen "Soft-Buffers". Es soll vermieden werden, daß jeder Service ein eigenen Soft-Buffer benötigt.
• - Soviel Signalisierung wie nötig aber gleichzeitig so wenig wie möglich. Je weniger Signalisierungsinformationen über die Luft gesendet werden müssen, desto mehr Nutzdaten können Übermittelt werden. Weiterhin besteht bei der Signalisierung die Gefahr der Missinterpretation durch Übertragungsfehler. Ein Bit was nicht Signalisiert wird, kann auch nicht verfälscht werden.
• - Umfassende Fehlererkennung zur Erhöhung der Signalisierungssicherheit.
• - Flexibles Scheduling um die mittlere Paketlaufzeit und folglich den Datendurchsatz zu erhöhen. Das bedeutet, daß Re- Transmissions so schnell wir möglich abgearbeitet werden sollen, um die Pakete aus dem Speicher zu bekommen und an die höheren Layer weiterzuleiten. Außerdem sollen die Nutzer zu beliebigen Zeitpunkten adressiert werden können.

However, the High Speed Downlink Package Access system currently specified for UMTS has the following additional requirements:

• - To operate different services with different QoS requirements simultaneously. These different QoS requirements of the data also require a different processing of the data in the HARQ process. This task can be solved in the most efficient and simple way possible.
• - Furthermore, the data arriving at the recipient should be able to be put back in a correct order. The recipient will usually not receive the data packets in the correct order, since individual data packets may be disturbed, which must then be requested again, while other data packets originally sent later are immediately correctly received.
• - As efficient as possible use of the so-called fast "soft buffer" mentioned above. It should be avoided that each service needs its own soft buffer.
• - As much signaling as necessary but at the same time as little as possible. The less signaling information has to be sent over the air, the more useful data can be transmitted. Furthermore, there is a risk of misinterpretation due to transmission errors in the signaling. A bit that is not signaled cannot be corrupted.
• - Comprehensive error detection to increase signaling security.
• - Flexible scheduling to increase the average packet runtime and consequently the data throughput. This means that retransmissions should be processed as quickly as possible in order to get the packets from memory and forward them to the higher layers. In addition, users should be able to be addressed at any time.

• - Jeder Service hat einen separaten Hybrid ARQ-Prozeß vor. Dies führt dazu, dass die Größe des Speichers, der für Hybrid ARQ benötigt wird, mit der Anzahl der verschiedenen Services zu multiplizieren ist.
• - Um sogenanntes In-Sequence Delivery zu gewährleisten wird im Moment diskutiert, ob eine Sequence Number im MAC oder eine Channel Number in HARQ Protokoll eingeführt wird. Anhand dieser Nummer kann das UE die Pakete wieder in die richtige Reihenfolge sortieren, bevor die Daten an die höheren Layer weitergegeben werden. Das Einführen von Paketnummern ermöglicht auch ein flexibles Scheduling.

The implementation approach currently adopted in the 3GPP provides the following solutions:

• - Each service has a separate Hybrid ARQ process. As a result, the amount of memory required for Hybrid ARQ must be multiplied by the number of different services.
• - To ensure what is known as in-sequence delivery, there is currently a discussion about whether a sequence number in the MAC or a channel number in the HARQ protocol will be introduced. Using this number, the UE can sort the packets in the correct order again before the data is passed on to the higher layers. The introduction of package numbers also enables flexible scheduling.

• - Die Pakete werden in der richtigen Reihenfolge gesendet, mit Ausnahme der Re-Transmissions.
• - Re-Transmissions werden so schnell wir möglich innerhalb eines Services gesendet.

The procedure presented here is based on the following basic rules:

• - The packets are sent in the correct order, with the exception of retransmissions.
• - Re-transmissions are sent as quickly as possible within a service.

• - Jedes Paket bekommt eine Service ID im Folgenden Flow ID genannt. Diese ID dient zur Kennzeichnung von Datenströmen mit gemeinsamen Eigenschaften.
• - Jedes Paket bekommt gegebenenfalls einen Re-Transmission Indikator zur Kennzeichnung wiederholter Pakete. Diese Kennzeichnung dient nur zur Fehlererkennung.
• - So viele Soft-Buffer wie N-Channel. Wobei N der minimalen Round-Trip Time entspricht.
• - Die Gegensatz zu bisherigen Verfahren vergibt die UE nun selbständig jedem empfangenen Paket eine Sequenz Nummer.

The invention requires for operation:

• - Each package is given a service ID in the following called Flow ID. This ID is used to identify data streams with common properties.
• - Each package may be given a re-transmission indicator to identify repeated packages. This marking is only used for error detection.
• - As many soft buffers as N-Channel. Where N corresponds to the minimum round trip time.
• - In contrast to previous methods, the UE now automatically assigns a sequence number to each packet received.

• - Es muss keine Sequence/Channel Nummer Signalisiert werden.
• - Re-Transmission kommen so schnell wie möglich gesendet.
• - Es wird ein Minimum an Soft-Buffer benötigt.
• - Verschiedene Services mit verschiedenen QoS Anforderungen können mit dem HARQ Prozess bearbeitet werden.
• - Fehlererkennung.
• - In-Sequence Delivery.

With the above requirements, the process offers these advantages:

• - No sequence / channel number needs to be signaled.
• - Re-transmission will be sent as soon as possible.
• - A minimum of soft buffer is required.
• - Different services with different QoS requirements can be processed with the HARQ process.
• - error detection.
• - In-sequence delivery.

The inventive step is to introduce the above mentioned rules for the autonomous allocation of the Sequnce number from UE.

Embodiments of the invention are shown in FIGS. 1 to 6.

In Fig. 1, an exemplary radio communication system is shown having a plurality of switching centers MSC, which are interconnected. As a rule, at least one of these switching devices MSC forms an access to further communication systems such as, for example, a fixed network communication system. Base stations NB (node B) are connected to the switching devices MSC as transmitting / receiving devices of the radio communication system. The base stations NB are connected to end devices, in particular subscriber terminals UE (user equipment) via communication links, which can be mobile or stationary end devices.

A unidirectional or a bidirectional communication link with an upward direction UL (uplink) from the subscriber terminal UE to the base station NB and / or a downlink DL (downlink) from the base station NB to the subscriber terminals can be established between the base station NB shown in FIG. 1 and the subscriber terminal UE UE exist.

Fig. 2 shows the trouble-free flow describes several packet transfers with an underlying N = 4 Channel Stop & Wait mechanism. The Up-Link UL is not considered here for reasons of clarity. It is assumed that an acknowledgment (ACK / NACK) for the individual packets arrives in the NodeB within the round trip time. In the simplest case, there is a fixed temporal relationship between data receipt and confirmation. A simple ACK / NACK is sufficient as confirmation.

The NodeB sends this in the Transmission Time Interval (TTI) 1 Package with number 1. However, this number is not transmitted has been. But since it is the first package that has arrived, the UE assigns sequence number 1 and places it in the first free soft buffer from where it is processed. The decreasing bar represents a TTI or Retransmission time counter that counts when a possible one Re-transmission can be sent at the earliest possible time. The round trip time (RTT) measured in TTIs of the number the N Channel should correspond to delays too avoid.

The package in TTI 2 will turn clockwise in the next free space written and with one from the UE at one increased package number. The following package in the TTI 3 is treated the same way. In the TTI 4 all soft buffer data have. The memory with packet number 1 signals the soft buffer Selector that it is finished (completely white background) and that he can take up data again in the next TTI.

In the TTI 5, the UE receives no data, e.g. B. can be another UE can be addressed. In this case the soft buffer switches Selector no further. The data in the stores will be continues to process and the TTI counter of each memory count further. The UE is addressed again for TTI 6. The Data block will turn clockwise in the next one free space written and with a Provide sequence number.

Fig. 3 describes a transmission with an erroneous packet for which retransmission is requested. In contrast to Fig. 2, package 1 arrives defective. The UE sends a NACK. According to the rule, a retransmission should now be sent as soon as possible. The next possible time for a retransmission is N TTIs later. If the TTI counter for the soft buffer with packet 1 has now arrived at N (exclamation mark is set), the UE expects a retransmission for the packet with the next data transmission. The defective packet remains in memory until it is combined with the re-transmission or it is rejected due to other QoS requirements e.g. E.g .: the maximum number of retransmissions has been reached. These rejection rules must be known in the sender and receiver.

If now through an ACK / NACK misinterpretation in the uplink If an error occurred, the NodeB in the TTI 6 would Transmit first package 5 without retransmission Indicator. Since the UE is expected to retransmit recognized this error.

In Fig. 4 as an example, data block 3 instead of Block 1 faulty. In contrast to FIG. 3, no retransmission can take place in the TTI 6, since the retransmission can be sent at the earliest N TTI later. The TTI counter in the TTI 5 for packet 3 is even smaller N, therefore in the TTI 6 packet 5 comes instead of a re-transmission of packet 3. The re-transmission takes place one TTI later when the TTI counter shows = N (exclamation mark in the TTI 6 for package 3). At this point the soft buffer selector jumps to the memory location where the TTI counter was set first. In the next TTI, the soft buffer selector continues clockwise from this position.

In FIG. 5 another service (Flow) in the existing HARQ process is transmitted to the UE in addition. Each flow has certain QoS requirements, among other things. This ID is transmitted with the package.

As in FIG. 3, packet 1 was received incorrectly in the UE. Instead of another packet in flow blue, a first packet on the prioritized flow magenta is transmitted to the TTI 3. As usual, this packet is written in the next free clockwise soft buffer.

The TTI 6 can now transmit in flow blue or magenta respectively. If flow blue were to be transmitted, a re- Transmission for packet 1 take place because of the TTI counter has expired. But since the magenta flow has priority, it will Submitted package in flow magenta in the next free Memory written and with the sequential sequence Number marked for flow magenta (Sequence Number 3). In the TTI 7 could in turn transmit both flows of data. Because in flow Magenta is not currently waiting for any more packages in NodeB B, Flow Blue can transmit the re-transmission for packet 1.

In contrast to FIG. 5, the magenta flow in FIG. 6 has more information to transmit. All buffers are occupied in TTI 4. However, since the magenta flow has a very high priority, a packet is still transmitted in the TTI 5. In this case, the buffer that is waiting the longest for retransmission is overwritten. The defective package 1 in flow blue is discarded and overwritten by an important package on flow magenta. The UE informs the higher layers that the transmission of packet 1 has been canceled. These can react differently depending on the configuration and QoS. Either the package will be sent again as soon as possible. This would correspond to switching to HARQ Type 1. In the case of streaming services, a missing packet can be ignored and the process continues. Or the UE again requests the entire SDU from the network.

Instead of overwriting the blue flow buffer, the UE would also have the data in the buffer with packet blue 2 can write. There would be no data loss come because an ACK has already been sent for the packet and not more is needed in the soft buffer. This procedure would Further optimize soft buffer memory usage. What the Representation here would unnecessarily complicate.

Claims (1)

Method for the transmission of data packets in a radio Communication system in which Data packets of a data stream on the send side with a data electricity-specific labeling, and at the receiving end, the data packets of the data stream are additionally transmitted a sequence number can be identified.