Method and apparatus for buffer storage of data packets which are to be transmitted via a connection that has been set up
View Patent ↗So-called LCH packets are defined in the Hiperlan Type 2 System for wire-free transmission of video and audio data streams. These LCH packets have a length of 54 data bytes. Furthermore, the Hiperlan/2 Standard provides for so-called ARQ messages to be sent back to the transmitter in an SCH packet in a QOS mode (Quality Of Service), in which all the LCH data packets must be confirmed by the receiver. Space for the LCH and SCH data packets must be provided in a buffer store in the Hiperlan/2 interface for each connection that is set up. When there is a possibility of several hundred connections having been set up, separate reservation of memory areas for LCH and SCH packets would involve considerable complexity for the memory organization. The invention proposes that only one common area be reserved for LCH and SCH packets in the buffer store. The section which is provided for each LCH package is of such a size that it corresponds to a value 2 n where nε[0, 1, 2, 3, . . . ], and this results in the hardware unit for the address calculation of these data section starts being greatly simplified. However, the area is chosen to be larger than actually required for the buffer storage of one LCH packet. The SCH packets, which likewise need to be buffer-stored, are entered in the unused part of such a section for an LCH packet. This considerably reduces the complexity for memory organization without having to leave a major proportion of the memory unused.
1. Method for buffer storage of data packets of a first type and of a second type which are to be transmitted via a connection that has been set up, with the data packets of the first type having a defined first length which does not correspond to a number 2n, nε[0, 1, 2, 3, . . . ] of data units, with the data packets of the second type having a defined second length which is shorter than the defined first length, and having a buffer store for the data packets, wherein the buffer store is subdivided into sections whose size is 2n data units, where 2n is greater than the defined first length plus the defined second length, and that part of the buffer store which is not occupied per data section is filled with the data from the data packets of the second type.
2. Method according to claim 1 , in which one area of the buffer store is reserved for a connection that has been set up, and this area is organized as a ring buffer in the buffer memory.
3. Method according to claim 1 , in which the data unit relates to a binary number with a length of 8 bits.
4. Method according to claim 1 , in which the buffer store is organized in memory words, whose length corresponds to an even multiple of, in particular to four times, the length of a data unit.
5. Method according to claim 1 , in which, during the buffer storage of a data packet, at least one byte is additionally stored which contains status information relating to the data packet, in particular as to whether the data packet has already been completely written.
6. Method according to claim 1 , in which the connection that has been set up is a connection based on the Hiperlan Type 2 Standard and a data packet of the first type is an LCH packet based on the Hiperlan Type 2 Standard, and a data packet of the second type is an SCH packet based on the Hiperlan Type 2 Standard.
7. Method according to claim 6 , in which a completely written, buffer-stored LCH data packet contains 48 payload data bytes and, with additional information, has a size of 52 bytes or 56 bytes, and the buffer store is subdivided into sections whose size is 64 bytes, with the remaining 12 or 8 bytes being used for buffer storage of an SCH packet.
8. Method according to claim 6 , in which an ARQ message based on the Hiperlan/2 Standard is stored in the SCH packet.
9. Method according to claim 1 , wherein the connection is a common connection with respect to the data packets of the first and of the second type.
10. Method according to claim 1 , the buffer store is filled in a two-pass approach, wherein the data packets of the first type are placed in the buffer store on a section-by-section basis in a first pass, and the part of the buffer store which is not occupied per data section is filled with the data from the data packets of the second type during a second pass.
11. Method according to claim 1 , wherein in a negative acknowledgement mode, a transmitter receives an acknowledgement message only when a data packet of the first type has been transmitted with one or more errors.
12. Apparatus for buffer storage of data packets of a first and of a second type which are to be transmitted via a connection that has been set up, in which the data packets of the first type have a defined first length which does not correspond to a number 2n, nε[0, 1, 2, 3, . . . ] of data units, with the data packets of the second type having a defined second length which is shorter than the defined first length, having a buffer store for the data packets, wherein the buffer store is subdivided into sections whose size is 2n data units, where 2n is greater than the defined first length plus the defined second length, and in that that part of the buffer store which is not occupied per data section is used for buffer-storing the data packets of the second type.
13. Apparatus according to claim 12 , in which the data unit relates to a binary number with a length of 8 bits.
14. Apparatus according to claim 12 , in which the buffer store is organized in memory words, whose length corresponds to an even multiple of, in particular to four times, the length of a data unit.
15. Apparatus according to claim 12 , having evaluation means for the status information, which is stored in at least one additional byte, for the buffer-stored data packet, in particular as to whether the data packet has already been completely written.
16. Apparatus according to claim 12 , in which a data area is reserved in the buffer store for the data packets which are to be transmitted via a connection that has been set up, with start and end information being stored for the reserved data area for a connection, and with a write pointer and a read pointer being provided for the data of the data packets of the first and the second type.
17. Apparatus according to claim 12 , wherein the connection is a common connection with respect to the data packets of the first and of the second type.
18. Apparatus according to claim 12 , the buffer stare is filled in a two-pass approach, wherein the data packets of the first type are placed in the buffer store on a section-by-section basis in a first pass, and the part of the buffer store which is not occupied per data section is filled with the data from the data packets of the second type during a second pass.
19. Apparatus according to claim 12 , wherein in a negative acknowledgement mode, a transmitter receives an acknowledgement message only when a data packet of the first type has been transmitted with one or more errors.