# US 8,570,869 B2 · Scalable error detection and cross-session timing synchronization for packet-switched transmission > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,570,869 B2 - Document ID: US8570869B2 - Status: Granted - Kind: B2 - Application number: 12/234,512 - Filed: 2008-09-19 - Published: 2009-06-18 - Granted: 2013-10-29 - Earliest claimed: 2007-09-21 - Assignees: Nokia Corporation - Applicants: Pasi Ojala; Ari Lakaniemi - Inventors: Pasi Ojala; Ari Lakaniemi - Web page: https://patentgrep.com/patent/US8570869B2 ## CPC - H04L 1/0083: {Formatting with frames or packets; Protocol or part of protocol for error control} - H04L 1/0061: {Error detection codes} - H04L 1/008: {where the control data relates to payload of a different packet} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Systems, methods and computer program codes are provided to facilitate error detection and timing synchronization of scalable data transmissions. To this end, checksum error detection is applied to the core layer and enhancement layers of the scalable payload data in such a way that dropping one or several enhancement layers from the payload data does not change the value of the checksum. Only one checksum is transmitted, e.g., in the payload or in the header of the lower-layer protocol. The transmitter modifies the encoded bit stream in such a manner that the entity in the network deploying the scalable payload and removing layers from the packet does not need to recalculate the checksum placed in the payload or packet header, even when the payload size is changed. ## Claims ### Claim 1 A method for encoding data into a bitstream, comprising: encoding a core layer of coded media data and at least one corresponding enhancement layer of coded media data into the bitstream; computing a single checksum for the core layer; and adding an additional field to each of the at least one enhancement layer such that any subsequent error check involving the respective at least one enhancement layer together with its respective additional field will match the single checksum if no data of the respective at least one enhancement layer or of its respective additional field is missing or in error, the single checksum thus being applicable for use in performing subsequent error checks of the core layer, and of each at least one enhancement layer, either alone or in combination with each lower corresponding enhancement layer and the core layer. ### Claim 2 (depends on 1) The method of claim 1, wherein the single checksum comprises a cyclic redundancy check checksum. ### Claim 3 (depends on 1) The method of claim 1, wherein the single checksum is encoded in a payload header for the encoded core layer and the at least one corresponding enhancement layer. ### Claim 4 (depends on 1) The method of claim 1, wherein the single checksum is encoded in a header of a lower-layer protocol for the encoded core layer and the at least one corresponding enhancement layer. ### Claim 5 (depends on 1) The method of claim 1, wherein the single checksum is encoded in a payload. ### Claim 6 (depends on 1) The method of claim 1, wherein the single checksum is encoded in a packet header. ### Claim 7 (depends on 1) The method of claim 1, wherein the additional field is added at the beginning of each enhancement layer. ### Claim 8 (depends on 1) The method of claim 1, wherein the additional field is added at the end of each enhancement layer. ### Claim 9 (depends on 1) The method of claim 1, wherein the additional field is encoded in a payload. ### Claim 10 (depends on 1) The method of claim 1, wherein the additional field is encoded in a packet header. ### Claim 11 (depends on 1) The method of claim 1, wherein the additional field is encoded in a payload header. ### Claim 12 (depends on 1) The method of claim 1, wherein the core layer and the at least one corresponding enhancement layer are transmitted to a remote device in a plurality of sessions. ### Claim 13 (depends on 1) A computer program product, embodied in a non-transitory computer-readable storage medium, comprising computer code configured to perform the processes of claim 1. ### Claim 14 An apparatus, comprising: an electronic device configured to: encode a core layer of coded media data and at least one corresponding enhancement layer of the coded media data into the bitstream; compute a single checksum for the core layer; and add an additional field to each of the at least one enhancement layer such that any subsequent error check involving the respective at least one enhancement layer together with its respective additional field will match the single checksum if no data of the respective at least one enhancement layer or of its respective additional field is missing or in error, the single checksum thus being applicable for use in performing subsequent error checks of the core layer, and of each at least one enhancement layer, either alone or in combination with each lower corresponding enhancement layer and the core layer. ### Claim 15 (depends on 14) The apparatus of claim 14, wherein the single checksum comprises a cyclic redundancy check checksum. ### Claim 16 (depends on 14) The apparatus of claim 14, wherein the single checksum is encoded in a payload header for the encoded core layer and the at least one corresponding enhancement layer. ### Claim 17 (depends on 14) The apparatus of claim 14, wherein the single checksum is encoded in a header of a lower-layer protocol for the encoded core layer and the at least one corresponding enhancement layer. ### Claim 18 (depends on 14) The apparatus of claim 14, wherein the single checksum is encoded in a payload. ### Claim 19 (depends on 14) The apparatus of claim 14, wherein the single checksum is encoded in a packet header. ### Claim 20 (depends on 14) The apparatus of claim 14, wherein the additional field is added at the beginning of each enhancement layer. ### Claim 21 (depends on 14) The apparatus of claim 14, wherein the additional field is added at the end of each enhancement layer. ### Claim 22 (depends on 14) The apparatus of claim 14, wherein the additional field is encoded in a payload. ### Claim 23 (depends on 14) The apparatus of claim 14, wherein the additional field is encoded in a packet header. ### Claim 24 (depends on 14) The apparatus of claim 14, wherein the additional field is encoded in a payload header. ### Claim 25 (depends on 14) The apparatus of claim 14, wherein the core layer and the at least one corresponding enhancement layer are transmitted to a remote device in a plurality of sessions. ### Claim 26 A method of processing encoded data from a bitstream, comprising: processing a core layer and at least one corresponding enhancement layer together with its respective additional field from the bitstream; processing a single checksum from the bitstream; and performing a check of one of the at least one corresponding enhancement layer, either alone or in combination with each lower corresponding enhancement layer and the core layer, using the single checksum, wherein the single checksum is usable regardless of the number of corresponding enhancement layers which are used in the check, and wherein an additional field has been previously added to each enhancement layer such that any subsequent check involving the respective enhancement layer together with its respective additional field will match the single checksum if no data of the respective enhancement layer or of its respective additional field is missing or in error. ### Claim 27 (depends on 26) The method of claim 26, wherein the single checksum comprises a cyclic redundancy check checksum. ### Claim 28 (depends on 26) The method of claim 26, wherein the single checksum is located in a payload header for the encoded core layer and the at least one corresponding enhancement layer. ### Claim 29 (depends on 26) The method of claim 26, wherein the single checksum is located in a header of a lower-layer protocol for the encoded core layer and the at least one corresponding enhancement layer. ### Claim 30 (depends on 26) The method of claim 26, wherein the single checksum is encoded in a payload. ### Claim 31 (depends on 26) The method of claim 26, wherein the single checksum is encoded in a packet header. ### Claim 32 (depends on 26) The method of claim 26, wherein the additional field has been added at the beginning of each enhancement layer. ### Claim 33 (depends on 26) The method of claim 26, wherein the additional field has been added at the end of each enhancement layer. ### Claim 34 (depends on 26) The method of claim 26, wherein the additional field is encoded in a payload. ### Claim 35 (depends on 26) The method of claim 26, wherein the additional field is encoded in a packet header. ### Claim 36 (depends on 26) The method of claim 26, wherein the additional field is encoded in a payload header. ### Claim 37 (depends on 26) The method of claim 26, wherein the core layer and the at least one corresponding enhancement layer are received from a remote device in a plurality of sessions, and further comprising: using the performed check to match the core layer with the at least one corresponding enhancement layer; and synchronizing the plurality of sessions including the core layer and the at least one corresponding enhancement layer. ### Claim 38 (depends on 26) The method of claim 26, wherein checks are performed simultaneously for each corresponding enhancement layer and the core layer, and further comprising using in a subsequent process only those layers which have been correctly received. ### Claim 39 (depends on 26) A computer program product, embodied in a non-transitory computer-readable storage medium, comprising computer code configured to perform the processes of claim 26. ### Claim 40 An apparatus, comprising: an electronic device configured to: process a core layer and at least one corresponding enhancement layer together with its respective additional field from the bitstream; process a single checksum from the bitstream; and perform a check of one of the at least one corresponding enhancement layer, either alone or in combination with each lower corresponding enhancement layer and the core layer, using the single checksum, wherein the single checksum is usable regardless of the number of corresponding enhancement layers which are used in the check, and wherein an additional field has been previously added to each enhancement layer such that the check involving the respective enhancement layer together with its respective additional field will match the single checksum if no data of the respective enhancement layer or of its respective additional field is missing or in error. ### Claim 41 (depends on 40) The apparatus of claim 40, wherein the single checksum comprises a cyclic redundancy check checksum. ### Claim 42 (depends on 40) The apparatus of claim 40, wherein the single checksum is located in a payload header for the encoded core layer and the at least one corresponding enhancement layer. ### Claim 43 (depends on 40) The apparatus of claim 40, wherein the single checksum is located in a header of a lower-layer protocol for the encoded core layer and the at least one corresponding enhancement layer. ### Claim 44 (depends on 40) The apparatus of claim 40, wherein the single checksum is encoded in a payload. ### Claim 45 (depends on 40) The apparatus of claim 40, wherein the single checksum is encoded in a packet header. ### Claim 46 (depends on 40) The apparatus of claim 40, wherein the additional field has been added at the beginning of each enhancement layer. ### Claim 47 (depends on 40) The apparatus of claim 40, wherein the additional field has been added at the end of each enhancement layer. ### Claim 48 (depends on 40) The apparatus of claim 40, wherein the additional field is encoded in a payload. ### Claim 49 (depends on 40) The apparatus of claim 40, wherein the additional field is encoded in a packet header. ### Claim 50 (depends on 40) The apparatus of claim 40, wherein the additional field is encoded in a payload header. ### Claim 51 (depends on 40) The apparatus of claim 40, wherein the core layer and the at least one corresponding enhancement layer are received from a remote device in a plurality of sessions, and wherein the electronic device is further configured to: use the performed check to match the core layer with the at least one corresponding enhancement layer; and synchronize the plurality of sessions including the core layer and the at least one corresponding enhancement layer. ### Claim 52 (depends on 40) The apparatus of claim 40, wherein checks are performed simultaneously for each corresponding enhancement layer and the core layer, and wherein the electronic device is further configured to use in a subsequent process only those layers which have been correctly received.