Synchronization of adaptive filter switching and channel equalization in full duplex (FDX) cable modems
Synchronizing methods and architectures for cable modems to transmit and receive Full Duplex (FDX) resource block allocations (RBAs) using filter switching and coordinated updating of equalization coefficients. A cable modem including a block of switchable filters, an analog front end (AFE) and a PHY/MAC System on a Chip (SoC) tuner to, at least in part, provide signals to switch the switchable filters in accordance with the RBA changes and synchronize updating tuner equalizations to match filter switching in a coordinated manner by marking received data at the AFE.
1. In a cable modem having an analog front end (AFE), a physical layer modulator (PHY) and a medium access control circuitry (MAC), that operates in full duplex (FDX) mode, and having a switchable filter block and variable equalizer coefficients in the PHY, a processor configured to:
receive a command at the MAC from the cable modem,
wherein the received command comprises a resource block allocation (RBA) change, wherein the RBA change comprises altering a first allocation of downstream and upstream transmission channels to a second, different allocation of downstream and upstream transmission channels, wherein altering the allocation comprises changing a channel from a downstream transmission direction to an upstream transmission direction, or vice-versa; and
trigger the MAC to send a filter switch control signal to the AFE based on the received command to:
cause the AFE, in response to the filter switch control signal, to switch a filter path and insert a filter switching mark in one or more samples received; and
cause the PHY to change its variable equalizer coefficients for the switched filter path in substantial synchronization with receiving samples including the filter switching mark from the AFE.
2. The processor of claim 1 wherein the cable modem is a data over cable service interface specification (DOCSIS) 3.1 FDX compliant modem.
3. The processor of claim 1 wherein the filter switching mark is inserted with the one or more samples received and passed from the AFE to the PHY via a high-speed serial interface framing structure.
4. The processor of claim 3 wherein the filter switching mark includes a filter configuration identifier corresponding to the switched filter path and an offset of the marked sample from a frame synchronization portion of the framing structure.
5. The processor of claim 1 wherein the variable equalizer coefficients reflect a calibration data determined by a characterization of a signal response during a transient, wherein the transient represents a real-time characterization of the signal response.
6. The processor of claim 1 wherein the variable equalizer coefficients reflect a pre-determined calibration data.
7. A communication system comprising:
a block of switchable filters to receive and transmit full duplex (FDX) signals according to a network provided resource block allocation (RBA) protocol; and
a tuner system in communication with the block of switchable filters, including physical layer (PHY) and medium access control (MAC) functionality, said MAC functionality including signaling to cause the block of switchable filters to change a filter path corresponding to a change in RBA and to mark received samples when the filter path changes, and a PHY synchronizing equalizer coefficient changes to compensate for the changed filter path based on the marked samples,
wherein the equalizer coefficient changes are selected by the PHY from a characterization data of a signal response during a transient, wherein the transient represents a real-time characterization of the signal for a switched filter path,
wherein the RBA change due to the signaling comprises altering a first allocation of downstream and upstream transmission channels to a second, different allocation of downstream and upstream transmission channels, wherein altering the allocation comprises changing a channel from a downstream transmission direction to an upstream transmission direction, or vice-versa.
8. The communication system of claim 7 wherein the tuner system further comprises an analog front end (AFE) to receive the MAC signaling, cause the filter path change in the block of switchable filters and mark the received samples using an interface and a framing structure to communicate the marked samples to the PHY.
9. The communication system of claim 8 wherein the interface comprises a high speed serial interface (HSIF) and wherein the framing structure includes a filter path change control message including a filter configuration identifier and an offset.
10. The communication system of claim 7 wherein at least a portion of the tuner system comprises a System on a Chip (SoC).
11. The communication system of claim 7 wherein the communication system comprises a data over cable service interface specification (DOCSIS) 3.1 FDX compliant modem.
12. The communication system of claim 11 wherein equalizer coefficient changes are adjustable by the PHY based on characterization of the signal response during the transient that include temperature changes.
13. A method of synchronizing filter switching and updating channel equalization coefficients in a cable modem having a switchable filter block, an analog front end (AFE), and a digital tuner including physical layer (PHY) and medium access control (MAC) functionality, the method comprising:
sending a filter switch control signal to the AFE from the MAC based on a received command to;
cause the AFE, in response to the filter switch control signal, to switch a filter path in the switchable filter block, and insert a filter switching mark in one or more samples received; and
cause the PHY to change its equalizer coefficients to compensate for a switched filter path coefficients from a characterization data of a signal response during a transient, wherein the transient represents a real-time characterization of the signal in substantial synchronization with receiving samples including the filter switching mark from the AFE,
wherein the received command comprises a resource block allocation (RBA), and wherein the RBA change comprises altering a first allocation of downstream and upstream transmission channels to a second, different allocation of downstream and upstream transmission channels, wherein altering the allocation comprises changing a channel from a downstream transmission direction to an upstream transmission direction, or vice-versa.
14. The method of claim 13 wherein the cable modem is a data over cable service interface specification (DOCSIS) 3.1 FDX compliant modem.
15. The method of claim 13 wherein the filter switching mark is inserted with the one or more samples received and passed from the AFE to the PHY via a high speed serial interface framing structure.
16. The method of claim 15 wherein the filter switching mark includes a filter configuration identifier corresponding to the switched filter path and an offset of the marked sample from a frame synchronization portion of the framing structure.
17. The method of claim 13 wherein the received command at the cable modem comprises the RBA change from a cable modem termination system (CMTS).
18. The method of claim 13 wherein the PHY changes its equalizer coefficients using the equalizer coefficients from the characterization of the signal response during the transient that include temperature changes.
19. The processor of claim 1 wherein the RBA receives commands from a cable modem termination system (CMTS).
20. The processor of claim 6 wherein the pre-determined calibration data includes adjustment for temperature changes.