WO2002067487A1

WO2002067487A1 - Method for transmitting data packets

Info

Publication number: WO2002067487A1
Application number: PCT/DE2002/000561
Authority: WO
Inventors: Frank Fitzek; Rolf Morich
Original assignee: Siemens Aktiengesellschaft
Priority date: 2001-02-19
Filing date: 2002-02-13
Publication date: 2002-08-29
Also published as: DE10108800A1

Abstract

The invention relates to a method for transmitting data packets(1, 2, 3, 4, 5, 6, 7, 8,..., N) by code division multiple access (CDMA) transmission technology via at least one first CDMA channel (K1) from a transmitter to a receiver. Redundancy information (R1,3, RN) is transmitted for defectively transmitted data packets (1, 3, N). According to the invention, said redundancy information (R1,3, RN) for defectively transmitted data packets (1, 3, N) is at least partially transmitted by at least one second CDMA channel (K2) which is allocated parallel to the first CDMA channel (K1).

Description

description

Method of transmitting data packets

The present invention relates to a method for transmitting data packets by means of the CDMA (code division multi-access) transmission technology via at least one first CDMA channel from a transmitter to a receiver, redundancy information being transmitted for incorrectly transmitted data packets.

The CDMA method is a method that enables multiple users to access one transmission channel. In this method, which is used, for example, in mobile radio systems, several users occupy the same frequency range, but the useful signal is coded differently for each user. A different code is used for the transmission of the bits for a first user than for a second user. The coding is based on a spread of the user data channel. The individual bits of a narrow-band useful signal are replaced by longer bit combinations. If you replace a bit with a bit combination of, for example, 10 bits *, you achieve a spread of a factor of 10. You need a higher transmission bandwidth, but you can. Use the transmission channel simultaneously for several user channels. The data of the individual users can be clearly distinguished from one another in the transmission channel. A major advantage of the CDMA method, for example over the known TDMA method, is the better utilization of the available transmission bandwidth.

Communication using CDMA transmission technology, like other communication methods, can be described using the ISO / OSI reference model. This reference model assigns the tasks involved in data communication to seven layers that build on one another. Each layer offers its services to the next higher layer and can in turn use the services of the layer directly below it. The task distribution of the layers in the ISO / OSI reference model is as follows:

1. Physical layer

The electrical, mechanical, functional and procedural parameters for controlling the physical transmission medium within the communication system are defined within the physical layer. The basic function is to provide the physical connection and its continuous operational readiness.

2nd data link layer

The data link layer is used to secure the transmission between two end devices on the individual sections of the entire transmission path. The necessary functions are segmentation, control and handling of errors. The data link layer is often divided into two sub-layers, the first of which is the so-called Medium Access Control (MAC) sub-layer, which ensures access to the transmission medium, while the second sub-layer is the so-called Logical Link Control (LLC -) Sub-layer is responsible for the management of the logical connection as well as the tasks of error detection and flow control.

network layer

The network layer takes over the establishment of a connection between two end devices, which is also referred to as "routing". This connection establishment includes the provision of suitable addressing, the switching, the connection establishment, the connection termination, the reset, interruptions, error detection and the transparent data transport between the end devices. The aspect of transparency includes adaptations of the characteristics of different data protection layers and also adaptations to the changing network topologies.

transport layer

The transport layer guarantees the network-independent and secure transfer of data between two processes or end devices. This includes establishing and maintaining the connection, multiplexing, error handling, and ordering the data.

5. Communication control layer

The communication control layer structures the data exchange and is required, for example, for synchronization.

6. Presentation layer

The presentation layer realizes in particular the adaptation of the data structures of communicating devices. Depending on the application, this can also affect aspects of alphabet conversions and data compression, for example. 7. Application layer

The application layer consists of application service elements that offer their services directly to the user of the communication system.

The present invention particularly relates to the quality of service for network layer segments of the ISO / OSI switching layer in the case of the wireless and the wired CDMA transmission technology. Segmentation of the network layer segments creates data link layer packets of the ISO / OSI data link layer. Previous approaches to improving the quality of service for network layer segments have focused on improving the quality of service for individual data link layer packets of the ISO / OSI data link layer.

The present invention is based on the object of specifying a generic method which results in an improved quality of service for network layer segments of the ISO / OSI network layer compared to the prior art.

This object is achieved by the features specified in claim 1.

Advantageous refinements and developments of the invention result from the subclaims.

The method according to the invention builds on the generic prior art in that the redundancy information for the incorrectly transmitted data packets is at least partially transmitted via at least one second CDMA channel which is or is allocated in parallel with the first CDMA channel. By using at least one second parallel CDMA channel, it is possible to forward redundancy information very efficiently for faulty packets, so that For example, the specified time window can be met.

In this context it can be provided in the method according to the invention that a predetermined number of data packets is to be transmitted from the transmitter to the receiver within such a time window. The solution according to the invention makes it possible for the predetermined number of data packets to be selected to be very high compared to the prior art, for example in such a way that the bandwidth of the first CDMA channel is practically fully utilized in the event of an error-free transmission.

In a particularly preferred embodiment of the method according to the invention, it is provided that the data packets are data link layer packets, and that a predetermined number of data link layer packets each corresponds to a network layer segment that is transferred from an SO / OSI network layer to an ISO / OSI data link layer, wherein reference is made to the above explanations in connection with the ISO / OSI reference model.

Furthermore, it can be provided in connection with the method according to the invention that the data packets, in particular the data link layer packets, within a first

Time period are transmitted from the transmitter to the receiver, and that the receiver is designed to confirm the data packets within a second time period.

In this context, it is provided in preferred embodiments of the method according to the invention that the second time period is a multiple of the first time period and that the following applies to the second time period: T2 “Tl x N, where T2 is the second time period, Tl is the first time period and N is the Number of data packets to be transmitted in a given time window. The shorter the second time period, the better the performance of the overall system. In preferred embodiments of the method according to the invention, it is further provided that the redundancy information for non-time-critical data packets is transmitted together with redundancy information for a later transmitted data packet. At least for the data packets sent at the beginning, this measure can help to ensure that redundancy information is only sent to the extent that is necessary to correct the incorrectly transmitted data packets.

In this context, in particular, in the context of the method according to the invention, redundancy information for data link layer packets which are assigned to an end section of a network layer segment can be transmitted as quickly as possible, in particular in order to be able to adhere to a predetermined time window. In some embodiments of the method according to the invention, it can be accepted that the last data packets, in particular the last data link layer packets of a network layer segment, receive redundancy information to a greater extent than is actually required, but that a predetermined time window can be adhered to with a higher probability.

In preferred embodiments of the method according to the invention, it is further provided that existing information about the network layer segments of the ISO / OSI network layer comprise a quality of service request.

Additionally or alternatively, it can be provided in the method according to the invention that existing information about the network layer segments of the ISO / OSI network layer comprise the assignment of the data link layer packets to the network layer segments. In this context in particular, the method according to the invention can further provide that the second CDMA channel or channels parallel to the first CDMA channel is based on measured and / or estimated channel state information and / or on the basis of available information about the Network layer segments are allocated, in particular the information about the network layer segments mentioned above. Depending on the quality of service requirement, parallel CDMA channels can then be allocated for support, for example, or the complete transmission of the data link layer packets of a network layer segment can be terminated. This can help improve energy consumption.

The method according to the invention preferably further provides that the redundancy information is ARQ (Automatic Repeat Reguest) information of type II. The parallel CDMA channels are then preferably used to forward the redundancy information in the form of ARQ information of type II for incorrectly transmitted data link layer packets.

In preferred embodiments of the method according to the invention, provision is furthermore preferably made for the extent of the redundancy information to depend on the time remaining until the end of the time window, in particular the time window within which the data link layer packets of a network layer segment are to be transmitted. In this way, it is possible in many cases to send exactly the amount of redundancy information, at least for the initially sent data packets, which is required to correct the faulty data backup packet or packets.

Each device for carrying out the method according to the invention falls within the scope of protection of the associated claims. The same applies to every device, in particular each communication terminal, which is designed to participate in the method according to the invention.

The invention is explained in more detail below with reference to an exemplary embodiment shown in the drawing.

It shows:

Figure 1 is a schematic representation illustrating the sequence of an embodiment of the method according to the invention.

According to FIG. 1, data link layer packets 1, 2, 3, 4, 5, 6, 7, 8, ..., N, which correspond to a switching layer segment, are to be transmitted by CDMA transmission technology via a first CDMA channel K1 from a transmitter (not shown in more detail) be transmitted to a receiver, also not shown. The transmission of the data link layer packets 1, 2, 3, 4, 5, 6, 7, 8, ..., N, of the network layer segment should take place within a time window TW. According to the illustration in FIG. 1, the individual data link layer packets 1, 2, 3, 4, 5, 6, 7, 8, ..., N are transmitted from the transmitter to the receiver within a first time period T1. The receiver is designed to confirm successfully transmitted data link layer packets within a second time period T2. 1, the data link layer packets 1, 3 and N are not transmitted correctly, while the other data link layer packets 2, 4, 5 and so on are successfully transmitted. The redundancy information for the incorrectly transmitted data link layer packets 1 and 3 are denoted by Rι, ₃ , while the redundancy information for the data link layer packet _N is denoted by R _N.

With reference to the representation of FIG. 1, the method according to the invention can, for example, proceed as follows: Assuming that the network layer (according to the ISO / OSI reference model with seven layers) transfers network layer segments to the data link layer and the length of their information corresponds to a multiple of the information length of a data link layer package of the ISO / OSI data link layer, the network layer segment is a predetermined number N of data link layer packets divided within the ISO / OSI data link layer and queued within the ISO / OSI data link layer. The assignment of data link layer packets 1, 2, 3, 4, 5, 6, 7, 8, ..., N to network layer segments is always known within the ISO / OSI data link layer. In addition, provision is made for network layer segments to be transmitted from the transmitter to the receiver within a predetermined time window TW, since otherwise a corresponding network layer segment loses its meaning. The data protection layer packets 1, 2, 3, 4, 5, 6, 7, 8, ..., N are transmitted by the CDMA-based communication system in the period T1 from the transmitter to the receiver. The receiver is designed to recognize successfully sent data link layer packets 2, 4, 5, 6, 7, 8 ... and to confirm them within a predetermined second time period T2. The second time period T2 is preferably a multiple of the first time period T1. In the case shown, the following applies to the second time period T2: T2 “T1 x N. The smaller the second time period T2, the better the performance of the overall system. At time t ₀ , the transmitter begins the sequential transmission of data link layer packets 1, 2, 3, 4, 5, 6, 7, 8, ..., N of a network layer segment on the initial first CDMA channel Kl. From the time t ₀ + T2, the transmitter receives information about the transmission success of the previously sent data link layer packets 1, 2, 3, 4, 5, 6, 7, 8, ..., N. For the data link layer packets 1, 3 and N which were not successfully transmitted, now additional redundancy information on a parallel second CDMA channel K2 is sent while the transmission of the data link layer packets in the queue continues on the initial first CDMA channel Kl. The scope of the redundancy information preferably depends on the remaining time until the end of the time window TW. This makes it possible, at least for the initially sent data packets, to send redundancy information to the extent that is required to correct a faulty data link layer packet. In the case shown, it is assumed that the data link layer package 1 is not time-critical. Therefore, its redundancy information Ri is sent together with the redundancy information R ₃ for the data link layer package 3 at the time of the data link layer package 6. For the faulty data link layer package N, the redundancy information R _{N is sent} as quickly as possible, since this has a much greater influence on the time window TW to be observed.

The features of the invention disclosed in the above description, in the drawing and in the claims can be essential for realizing the invention both individually and in any combination.

Claims

claims

1. Method for data packets (1, 2, 3, 4, 5, 6, 7, 8, ..., N) by means of the CDMA (code division multiple access) transmission technology via at least one first CDMA channel (Kl) to be transmitted from a transmitter to a receiver, redundant information (Rι, ₃ , R _M ) being transmitted for incorrectly transmitted data packets (1, 3, N), characterized in that the redundancy information (R_, ₃ , RN ) for the incorrectly transmitted data packets (1, 3, N) are at least partially transmitted via at least one second CDMA channel (K2) which is or will be allocated in parallel to the first CDMA channel (Kl).

2. The method according to claim 1, characterized in that a predetermined number (N) of data packets (1, 2, 3, 4, 5, 6, 7, 8, ..., N) within a time window (TW) from the transmitter to be transmitted to the recipient.

3. The method according to any one of the preceding claims, since you rchgek characterized that the data packets (1, 2, 3, 4, 5, 6, 7, 8, ..., N) are data link layer packets, and that a predetermined number ( N) each of data link layer packets corresponds to a network layer segment that is transferred from an ISO / OSI network layer to an ISO / OSI data link layer.

4. The method according to any one of the preceding claims, characterized in that the data packets (1, 2, 3, 4, 5, 6, 7, 8, ..., N) are transmitted from the transmitter to the receiver within a first time period (Tl) , and that the receiver is designed to confirm successfully transmitted data packets within a second period (T2).

5. The method as claimed in one of the preceding claims, that the second time period (T2) is a multiple of the first time period (Tl), and that the following applies to the second time period (T2): T2 «Tl * N.

6. The method according to any one of the preceding claims, since you are characterized in that redundancy information (Ri) for non-time-critical data packets (1) is transmitted together with redundancy information (R ₃ ) for a later transmitted data packet (3).

7. The method as claimed in one of the preceding claims, characterized in that redundancy information (R _N ) for data link layer packets (N) which are assigned to an end section of a network layer segment is transmitted as quickly as possible, in particular in order to be able to adhere to the time window (TW) ,

8. The method as claimed in one of the preceding claims, namely that existing information about the network layer segments of the ISO / OSI network layer comprise a quality of service request.

9. The method according to any one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that existing information on the network layer segments of the ISO / OSI network layer include the assignment of the data link layer packets to the network layer segments.

10. The method according to any one of the preceding claims, characterized in that the second CDMA channels (K2, K3, K4) parallel to the first CDMA channel (Kl) are allocated on the basis of measured and / or estimated channel status information and / or on the basis of available information about the network layer segments.

11. The method as claimed in one of the preceding claims, that the redundancy information is ARQ (Automatic Repeat Request) information of type II.

12. The method according to any one of the preceding claims, characterized in that the scope of the redundancy information (Rι, ₂ , R _N ) depends on the remaining time to the end of the time window (TW).

13. Device for performing the method according to one of claims 1 to 12.

14. Device, in particular communication terminal, which is designed to participate in the method according to one of claims 1 to 12.