Discrete multi-tone (DMT) system and method that communicates a data pump data stream between a general purpose CPU and a DSP via a buffering scheme
View Patent ↗The apparatus and method herein splits the function of a digital subscriber line (DSL) modem data pump between a digital signal processor (DSP 106 ) and a general purpose host central processing unit (CPU 102 ). The DSP ( 106 ) handles all front end data pump processing such as interface to an analog front end ( 108 and 110 ), FFT processing, FEQ processing, QAM decoding, and bit formatting. The host CPU ( 102 ) handles all back end data pump processing such as DMT tone deordering, data deinterleaving, error detection and correcting, bit descrambling, CRC processing, and the like. In order to enable the DSP ( 106 ) and the CPU ( 102 ) to communicate with each other effectively, buffers ( 132 ) under the control of specialized buffer management methodology (FIG. 4 ) are used.
1. A method for communicating DSL data symbols, the method comprising the steps of:
generating one or more DSL data symbols in a first processor;
receiving, in a second processor, the one or more DSL data symbols over time and buffering the DSL data symbols in a buffer;
retrieving, in the second processor, the one or more DSL data symbols from the buffer and transmitting the one or more DSL data symbols one after another over a communication media;
transmitting from the second processor, when the buffer contains no DSL data symbols, a redundant DSL symbol over the communication media; and
correcting, when the buffer is written to contain DSL data symbols, a state of DSL transmission to compensate for the previous communication of redundant symbols;
wherein the method has two modes of operation, a first mode of operation being where the second processor dedicates X MIPS to processing data packets and a second mode of operation being where the second processor dedicates Y MIPS to processing the data packets wherein Y is less than X.
2. The method of claim 1 wherein the DSL symbols contain TCP/IP packets that are assembled into ATM data cells.
3. A system for communicating DSL data symbols, the system comprising:
a first processor wherein the first processor generates one or more DSL data symbols; and
a second processor wherein the second processor receives the one or more DSL data symbols from the first processor and transmits the one or more DSL data symbols over a communication media;
wherein the second processor transmits a redundant DSL data symbol over the communication media in response to the first processor being unable to timely provide a new DSL data symbol;
wherein the system has two modes of operation, a first mode of operation being where the second processor dedicates X MIPS to processing data packets and a second mode of operation being where the second processor dedicates Y MIPS to processing the data packets wherein Y is less than X.
4. A system as in claim 3 , further comprising:
a buffer, coupled to the first and second processors, the buffer storing the one or more DSL data symbols from the first processor.
5. A system as in claim 3 , wherein the first processor is programmed to convert analog data to digital data and to configure the digital data into data packets, and wherein the second processor is programmed to configure the data packets into byte-ordered information.
6. A system as in claim 3 , wherein the first processor comprises a digital signal processor (DSP) designed to convert data between the time domain and the frequency domain to create data packets from a serial stream of data.
7. A system as in claim 3 , wherein the second processor is a host processor for a computer, and wherein the host processor is coupled to the first processor by a bus comprising address lines, data lines, and at least one control line.
8. A system as in claim 3 , wherein the system processes two or more of G.lite data streams, V.90 data streams, and ADSL data streams.
9. A system as in claim 3 , wherein the system processes all three of G.lite data streams, V.90 data streams, and ADSL data streams.
10. A system as in claim 3 , wherein the second processor is programmed to assemble and/or dissasemble ATM data packets which are then configured for transmission as DMT symbols.
11. A system as in claim 3 , wherein the system has three modes of operation, a first mode of operation being where the second processor dedicates X MIPS to processing data packets, a second mode of operation being where the second processor dedicates Y MIPS to processing the data packets where Y is less than X but nonzero, and a third mode of operation where the second processor devotes no MIPS to processing the data packets.
12. A system as in claim 3 , wherein a buffer is coupled between the first processor and the second processor, and wherein a plurality of data packets are queued into the buffer before the second processor begins to process the plurality of data packets.
13. A system as in claim 3 , wherein a buffer is coupled between the first processor and the second processor wherein a plurality of data packets are queued into the buffer before the first processor begins to process the plurality of data packets.
14. A system as in claim 3 , wherein the second processor transmits the redundant DSL data symbol if a buffer contains no new valid data to transmit.
15. A system as in claim 3 , wherein the redundant DSL data symbol comprises a number N of redundant DSL data symbols wherein N is a whole number greater than one, and wherein a number N of newly provided symbols are discarded and not transmitted to offset the N redundant DSL data symbols previously transmitted.
16. A system as in claim 3 , wherein the DSL data symbols contain TCP/IP packets that are assembled into ATM data cells.
17. A method for communicating one or more DSL data symbols, the method comprising:
generating the one or more DSL data symbols in a first processor;
providing the one or more DSL data symbols to the second processor via a data bus;
receiving the one or more DSL data symbols from the data bus and storing the one or more DSL data symbols in a buffer;
retrieving the one or more DSL data symbols from the buffer and sequentially transmitting the one or more DSL data symbols from the second processor along a transmission line;
determining if one or more new DSL data symbols are available in the buffer;
transmitting one or more redundant DSL data symbols from the second processor along the transmission line if the one or more DSL data symbols are not available in the buffer; and
correcting, when one or more new DSL data symbols are available in the buffer, state of the DSL transmission to compensate for previously communicating the one or more redundant DSL data symbols;
wherein the method has two modes of operation, a first mode of operation being where the second processor dedicates X MIPS to prcessing data packets and a second mode of operation being where the second processor dedicates Y MIPS to processing the data packets wherein Y is less than X.
18. A method as in claim 17 , wherein the step of correcting comprises determining if the one or more redundant DSL data symbols belong to real time content or non-real time content.
19. A method as in claim 17 , wherein the step of correcting comprises discarding at least a portion of the one or more new DSL data symbols.
20. A method as in claim 17 , wherein the step of correcting comprises transmitting the one or more new DSL data symbols if the one or more redundant DSL data symbols belong to non-real time content.
21. A method as in claim 17 , wherein the step of correcting comprises never transmitting the one or more new DSL data symbols if the one or more redundant DSL data symbols belong to real time content.
22. A method as in claim 17 , wherein the buffer comprises a FIFO buffer.
23. A method as in claim 17 , wherein the one or more DSL data symbols comprise packets.
24. A method as in claim 17 , wherein the one or more DSL data symbols comprise TCP/IP packets that are assembled into ATM data cells.