초록 ▼

There is disclosed a method of transferring input data packets from an upper layer to a lower layer of a stack of communication protocol layers, wherein the lower layer supports variable sized packets. One input data packet is received from the upper layer. This input data packet is segmented into s

There is disclosed a method of transferring input data packets from an upper layer to a lower layer of a stack of communication protocol layers, wherein the lower layer supports variable sized packets. One input data packet is received from the upper layer. This input data packet is segmented into several data segments the size of which is selected in a list of a given number N of predetermined segment size values. Signalling information is added to each data segment to form output data packets, which is delivered to a lower layer. Selection of the segment size value is performed according to an algorithm which minimizes the overall ineffective data and/or the overall signalling information. Thus, the transmission overhead generated by the segmentation scheme is reduced.

대표청구항 ▼

The invention claimed is: 1. A method of transferring input data packets from an upper layer of a stack of communication protocol layers to a lower layer supporting variable sized packets in a communications system, said method comprising: receiving, at a transmitting device, one input data packet

The invention claimed is: 1. A method of transferring input data packets from an upper layer of a stack of communication protocol layers to a lower layer supporting variable sized packets in a communications system, said method comprising: receiving, at a transmitting device, one input data packet from the upper layer; segmenting, at the transmitting device, said input data packet into several effective data parts to form respective data segments; selecting, at the transmitting device, a size of each one of said data segments from a list comprising a given number n of predetermined segment size values; adding, at the transmitting device, ineffective data to each one of said data segments when required to reach said selected segment size value, wherein the selecting of one of said segment size values from said list is performed according to a selection algorithm which minimizes overall ineffective data and/or overall signaling information and also which selects a greatest segment size value that minimizes the ineffective data in the data segment; adding, at the transmitting device, associated signaling information to each of said respective data segments so as to generate respective output data packets; and delivering, at the transmitting device, said output data packets to the lower layer. 2. A method of transferring input data packets from an upper layer of a stack of communication protocol layers to a lower layer supporting variable sized packets in a communications system, said method comprising: receiving, at a transmitting device, one input data packet from the upper layer; segmenting, at the transmitting device, said input data packet into several effective data parts to form respective data segments; selecting, at the transmitting device, a size of each one of said data segments from a list comprising a given number n of predetermined segment size values; adding, at the transmitting device, ineffective data to each one of said data segments when required to reach said selected segment size value, wherein the selecting of one of said segment size values from said list is performed according to a selection algorithm which minimizes overall ineffective data and/or overall signaling information; adding, at the transmitting device, associated signaling information to each of said respective data segments so as to generate respective output data packets; and delivering, at the transmitting device, said output data packets to the lower layer, wherein the selecting is performed according to the selection algorithm applying the following rules: selecting a greatest segment size value in the list which is shorter than a length of the input data packet when selecting the size of each one of said data segments except for a last data segment, and selecting a segment size value for the last data segment that contains the whole last effective data part and minimizes the length of the ineffective data part in said last data segment. 3. The method of any one of the claims 1 or 2, wherein the signaling information is added to the data segment in a header field and/or in a trailer field. 4. The method of claim 3, wherein the trailer field comprises a CRC, which is calculated based on at least some of the bits of the header field and on the data segment. 5. The method of claim 3, wherein a size of the signaling information is a constant value, which is independent of the segment size. 6. The method of claim 3, wherein the list of predetermined segment size values is such that after adding the signaling information, the output data packet size values are respective multiples of the smallest one of them. 7. The method of recovering input data packets received from a lower layer in a flow of output data packets generated according to claim 3, comprising: detecting and retrieving, at the receiving device, the size of the output data packets wherein all the values in the list of predetermined segment size values are considered; retrieving, at the receiving device, data segments from respective retrieved output data packets; and reassembling, at the receiving device, the retrieved data segments to form input data packets to be provided to the upper layer. 8. The method of claim 7, further comprising: detecting the beginning of the flow of packets; and detecting and retrieving the size of the output data packets periodically, with a period corresponding with a smallest output data packet size value. 9. The method of claim 8, wherein the signaling information includes a CRC and wherein the step of retrieving output data packets is based on CRC calculations. 10. The method of claim 9, wherein the step of retrieving output data packets, comprises: calculating for i=0 to i=n−1 and for j=0 to j=n(i)−1, periodic and concurrent cyclic redundancy codes CRC(i,j), wherein the respective calculation of each of said cyclic redundancy codes CRC(i,j) is performed on a given number S(i) of data words, with a respective period of S(i), and is started at an instant corresponding to a given number j×S(0) of data words after the beginning of the reception of the flow of output data packets, where i and j are positive integers, where S(i), and n(i) are strictly positive integers, where S(i) denotes the size value of one output data packet, where S(0) designates the smallest output packet data size value, and where n(i) is such that S(i)=n(i)×S(0); and retrieving output data packets based on successful CRC calculation results only. 11. A device for transferring input data packets from an upper layer of a stack of communication protocol layers to a lower layer supporting variable sized packets, comprising: means for receiving one input data packet from the upper layer; means for segmenting said input data packet into several effective data parts to form respective data segments; means for selecting a size of each one of said data segments from a list comprising a given number n of predetermined segment size values; means for adding ineffective data to each one of said data segments when required to reach said selected segment size value, wherein the selection of one of said segment size values from said list is performed according to an algorithm minimizing overall ineffective data and/or overall signaling information and also selecting a greatest segment size value that minimizes the ineffective data in the data segment; means for adding associated signaling information to each of said data segments so as to generate respective output data packets; and means for delivering said output data packets to the lower layer. 12. The device for recovering data packets from the data packets delivered to the lower layer by the device according to claim 11, comprising: means for detecting and retrieving data packets delivered to the lower layer, the means for detecting and retrieving including means for considering all the values in the list of predetermined segment size values; means for retrieving data segments from respective retrieved data packets delivered to the lower layer; and means for reassembling the retrieved data segments to form input data packets to be provided to the upper layer. 13. A device for transferring input data packets from an upper layer of a stack of communication protocol layers to a lower layer supporting variable sized packets, comprising: means for receiving one input data packet from the upper layer; means for segmenting said input data packet into several effective data parts to form respective data segments; means for selecting a size of each one of said data segments from a list comprising a given number n of predetermined segment size values; means for adding ineffective data to each one of said data segments when required to reach said selected segment size value, wherein the selecting of one of said segment size values from said list is performed according to a selection algorithm which minimizes overall ineffective data and/or overall signaling information; means for adding associated signaling information to each of said respective data segments so as to generate respective output data packets; and means for delivering said output data packets to the lower layer, wherein the selecting is performed according to the selection algorithm applying the following rules: selecting a greatest segment size value in the list which is shorter than a length of the input data packet when selecting the size of each one of said data segments except for a last data segment, and selecting a segment size value for the last data segment that contains the whole last effective data part and minimizes the length of the ineffective data part in said last data segment.