Adaptive facsimile redundancy
Forward error correction is implemented in a facsimile transmission using adaptive redundancy. The depth of redundancy can change based on a number of factors, including lost packet counts, transport type, facsimile modulation type, call history or facsimile engine state changes. Separate redundancy depths can be implemented for image and for control phases of the facsimile call. Redundancy depth can be increased or decreased during a facsimile call, and may be maintained at an increased level once encountered transmission impediments are overcome. Variable redundancy can be provided for specific portions of the call, such as temporarily increased redundancy during control phases. Adaptive redundancy may be implemented at one or more endpoints or nodes in a packet-switched communication network through which the facsimile call passes. The adaptive redundancy contributes to improving successful facsimile call completion in communication networks that may be prone to error losses.
1. A facsimile device for processing a facsimile call, comprising:
a memory storage for storing at least one redundancy depth value for transmission of facsimile data, the facsimile data including facsimile image data and facsimile control data;
a redundancy controller communicatively coupled to the memory storage and being operable to calculate at least one variable number of duplicate consecutive packets to be sent by the facsimile device while processing the facsimile call based at least in part on at least one input related to operation of the facsimile device,
wherein each of the at least one variable number of duplicate consecutive packets contain duplicate payloads of at least some of one of the facsimile image data and the facsimile control data, and
wherein the redundancy controller is further operable to set the at least one redundancy depth value to the calculated at least one variable number of duplicate consecutive packets, and to store the at least one redundancy depth value in the memory storage; and
a processor communicatively coupled to the memory storage and being operable to access and apply the at least one redundancy depth value in processing the facsimile call in order to provide the calculated at least one variable number of duplicate consecutive packets in a facsimile transmission,
wherein the at least one redundancy depth value comprises an image redundancy depth value for transmission of the facsimile image data, and a control redundancy depth value for transmission of the facsimile control data, and
wherein the redundancy controller is further operable to modulate the control redundancy depth value in accordance with operations during a control phase of the facsimile call, the modulated control redundancy depth value being different from the image redundancy depth value.
2. The device according to claim 1 , wherein a previous redundancy depth value that is stored in the memory storage is used to calculate the at least one variable number of duplicate consecutive packets.
3. The device according to claim 2 , wherein the redundancy controller is operable to increase or decrease the previous redundancy depth value to calculate the at least one variable number of duplicate consecutive packets.
4. The device according to claim 3 , wherein the redundancy controller is operable to increase the previous redundancy depth value to calculate the at least one variable number of duplicate consecutive packets, and the processor is operable to provide a command retry with the so calculated at least one variable number of duplicate consecutive packets.
5. The device according to claim 1 , further comprising:
a second controller communicatively coupled to the redundancy controller and being operable to provide a parameter value related to facsimile call processing to the redundancy controller as an input to which the redundancy controller is responsive.
6. The device according to claim 5 , wherein the second controller includes one or more of a call control unit, a storage device for storing historical facsimile call data, a lost packet detector, a transport engine, a configuration manager, an external network monitoring device or a facsimile engine.
7. The device according to claim 5 , wherein the parameter value is related to one or more of a prior call history, configured or negotiated transport type, lost packet counts, facsimile modulation type or a facsimile engine state change.
8. The device according to claim 7 , wherein the facsimile engine state change comprises one or more of a change between image and control phases, modem train-down, command retry, transmitting silence or managing error correction mode commands.
9. A method of processing a facsimile call by a facsimile device, the facsimile device including a controller and a processor, the method comprising:
obtaining at least one redundancy depth value for transmission of facsimile data, the facsimile data including facsimile image data and facsimile control data;
calculating, by the controller, at least one variable number of duplicate consecutive packets to be sent by the facsimile device while processing the facsimile call based at least in part on at least one input related to operation of the facsimile device, each of the at least one variable number of duplicate consecutive packets containing duplicate payloads of at least some of one of the facsimile image data and the facsimile control data;
setting, by the controller, the at least one redundancy depth value to the calculated at least one variable number of duplicate consecutive packets;
applying, by the processor, the at least one redundancy depth value in processing the facsimile call in order to provide the calculated at least one variable number of duplicate consecutive packets in a facsimile transmission, the at least one redundancy depth value comprising an image redundancy depth value for transmission of the facsimile image data, and a control redundancy depth value for transmission of the facsimile control data; and
modulating, by the controller, the control redundancy depth value in accordance with operations during a control phase of the facsimile call, the modulated control redundancy depth value being different from the image redundancy depth value.
10. The method according to claim 9 , wherein the calculating of the at least one variable number of duplicate consecutive packets includes calculating the at least one variable number of duplicate consecutive packets using a previous redundancy depth value.
11. The method according to claim 10 , wherein the calculating of the at least one variable number of duplicate consecutive packets includes increasing or decreasing the previous redundancy depth value.
12. The method according to claim 9 , wherein the facsimile device further includes a second controller, wherein the method further comprises:
providing, by the second controller, a parameter value related to facsimile call processing to the controller as an input to which the controller is responsive, and
wherein the calculating of the at least one variable number of duplicate consecutive packets includes calculating the at least one variable number of duplicate consecutive packets based at least in part on the parameter value related to the facsimile call processing.
13. The method according to claim 12 , wherein the parameter value is related to one or more of a prior call history, a configured or negotiated transport type, lost packet counts, a facsimile modulation type, and a facsimile engine state change.
14. The method according to claim 13 , wherein the facsimile engine state change comprises one or more of a change between image and control phases, a modem train-down, a command retry, transmitting silence, and managing error correction mode commands.
15. The method according to claim 11 , wherein the calculating of the at least one variable number of duplicate consecutive packets includes increasing the previous redundancy depth value, and wherein the method further comprises:
providing, by the processor, a command retry with the calculated at least one variable number of duplicate consecutive packets.