Method and apparatus for establishing circuit connections over local area networks with frequency selective impairments

• US 20040081127A1
• Filed: 04/21/2003
• Published: 04/29/2004
• Est. Priority Date: 04/20/2002
• Status: Active Grant

• Current Assignee: Conexant Systems Incorporated (Synaptics Incorporated)
• Original Assignee: Conexant Systems Incorporated (Synaptics Incorporated)
• Inventors: Gardner, Steven H., Petranovich, James E.
• Granted Patent: US 7,450,604 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04N 1/00204 with a digital computer or a digital computer system, e.g. an internet server programmed control between transmitter and receiver or between image input and image output device H04N1/32561
• CPC Class Codes: H04N 1/00209 Transmitting or receiving image data, e.g. facsimile data, via a computer, e.g. using e-mail, a computer network, the internet, I-fax
• CPC Class Codes: H04N 2201/0034 Details of the connection, e.g. connector, interface

Abstract

Local area network bandwidth is partitioned into periodic data frames. Data frames are further segregated into spectrum and time slots. Bandwidth reserved by assigning spectrum and time slots to particular circuit connections; enabling deterministic data transfer from source to destination nodes. Bandwidth reservations are broadcast to nodes attached to network.

Claims

1. A method for establishing a circuit connection over a network comprising the steps of:

discovering the existing allocation of network resources;

selecting a portion of the available network resources for transmitting information to a data destination node; and

broadcasting the selection of network resources to other nodes attached to the network.

2. A method for establishing a circuit connection over a network comprising the steps of:

determining the transfer function profile of a medium connecting a data source node to a data destination node;

creating a resource allocation profile of existing spectrum and time-slot allocation of the medium;

selecting from the resource allocation profile a portion of the available spectrum and time-slots for transmitting information to the data destination node in accordance with the transfer function profile; and

broadcasting the selection of spectrum and time-slots to other nodes attached to the medium.

3. The method of claim 2 further comprising the steps of:

broadcasting a circuit connection identifier that associates the selected spectrum and time-slots;

receiving source data from computer readable media;

modulating a set of carriers according to the received source data and according to a modulation mode dictated by an established modulation density for each carrier; and

conveying the modulated carriers to the data destination node.

4. The method of claim 3 further comprising the steps of:

receiving the broadcast selection of spectrum and time-slots selected for transmitting information to the data destination node;

receiving the circuit connection identifier;

identifying the carrier frequencies and time-slots that are carrying information for the data destination node by associating the received selection of spectrum and time-slots with a circuit connection identifier; and

demodulating each of the carriers at the identified frequencies according to a demodulation mode dictated by an established modulation density.

5. The method of claim 2 further comprising the steps of:

periodically refreshing the transfer function profile and the resource allocation profile of existing spectrum and time-slot allocation of the medium;

considering the efficacy of the selected portion of the available spectrum and time-slots in light of the verified transfer function profile;

selecting a new portion of the available spectrum and time-slots for transmitting information to the data destination node if the efficiency of resource utilization may be improved by a predetermined threshold; and

broadcasting the new selection of spectrum and time-slots to other nodes attached to the medium.

6. The method of claim 2 wherein the step of determining the transfer function profile from a data source node to a data destination node comprises of the steps of:

sending a sounding message from a data source node to a data destination node;

measuring the quality profile of the sounding message arriving at the data destination node; and

establishing a modulation density based on the quality profile of the sounding message for each of a plurality of carriers conveyed through the medium from the data source node to the data destination node.

7. The method of claim 6 further comprising the steps of:

identifying impairment sources arriving with the sounding message;

classifying each impairment source as either a narrow-band interferer or a wide-band interferer;

setting to nil the established modulation density for carriers that are imposed upon by a narrow-band interferer; and

if wide-band interferers exist;

sending a sounding message from the data source node to the data destination node and if any wide-band interferers desist, upgrading the established modulation density for the carriers imposed upon by the desisting wide-band interferers.

8. The method of claim 2 wherein the step of creating a resources allocation profile comprises the steps of:

receiving a first beacon message that identifies spectrum and time-slots that are allocated;

creating a profile table based on the information received in the first beacon message;

receiving subsequent beacon messages from the medium on a periodic basis; and

updating the profile table to reflect the spectrum and time-slots identified in the subsequent beacon message as being allocated.

9. The method of claim 2 wherein the step of selecting a portion of the available spectrum and time-slots for transmitting information to the data destination node is comprised of the steps of:

receiving a required data bandwidth indicator from the data source node;

consulting the transfer function profile from the source node to the destination node to determine the data carrying capacity of a plurality of carriers conveyed through the medium as dictated by an established modulation density for each carrier; and

selecting one or more carriers and time-slots from those carrier and time-slots identified as available in the resource allocation profile to support the amount of bandwidth defined in the required data bandwidth indicator.

10. The method of claim 2 wherein the step of broadcasting the selection of spectrum and time-slots to other nodes comprises the steps of:

creating a beacon message that comprises the current selection information; and

conveying the beacon message to the medium on a predefined interval.

11. The method of claim 10 wherein the beacon message further comprises the contents of a resource allocation table that indicates perceived utilization of spectrum and time-slots created by receiving a plurality of beacon messages from the medium on a periodic basis that indicate assignment of spectrum and time-slots.

12. A networking control unit comprising:

PHY/MAC unit that communicates with other PHY/MAC units in other networking control units using a physical medium or wireless propagation of a plurality of carrier signals;

resource allocation tracking unit that periodically receives a message from the PHY/MAC unit that indicates a current allocation of carrier signals and generates a resource allocation profile that indicates what carrier frequencies are currently in use;

host data interface that receives information from computer readable media;

circuit connection establishment unit that creates a transfer function profile for the medium or wireless environment between the PHY/MAC and a PHY/MAC that responds to a destination address received from the host data interface and selects a set of carrier frequencies that may be used to sustain a circuit connection to the PHY/MAC that responds to the destination address and wherein the carrier frequencies are selected from a set of carrier frequencies indicated as not being currently in use by the resource allocation profile and the number of carrier signals selected is dictated by the transfer function profile;

modulation unit that accepts data from the host data interface and generates a set of carrier signals that are modulated according to the data and wherein the carrier signals generated are set to frequencies selected by the circuit connection establishment unit; and

resource usage broadcast unit that causes the PHY/MAC to broadcast a message either wirelessly or through the physical medium that indicates what carrier frequencies are currently being used by the modulation unit.

13. The networking control unit of claim 12 wherein the modulation unit modulates each carrier that it generates according to an established modulation density.

14. The networking control unit of claim 13 further comprising:

demodulation unit that receives a set of carriers from the PHY/MAC wherein the carriers received by the demodulation unit are dictated according to a circuit connection identifier and carrier frequencies enumerated in the resource allocation profile as being allocated to that circuit connection identifier and wherein the demodulation unit selects a demodulation mode according to an established modulation density specified in the transfer function profile.

15. The networking control unit of claim 12 further comprising:

connection evaluation unit that periodically causes the circuit connection establishment unit to create a new transfer function profile for the medium or wireless environment between the PHY/MAC and the PHY/MAC that responds to the destination address received from the host data interface and further causes the circuit connection establishment unit to select a new set of carrier frequencies if the difference between the amount of bandwidth required to sustain a required bandwidth by the new set of carrier frequencies is less than the bandwidth required by the existing set of carrier frequencies by a predefined margin.

16. The networking control unit of claim 12 wherein the circuit connection establishment unit comprises:

sounding unit that conveys a sounding message to the PHY/MAC so as to convey the sounding message to the PHY/MAC in a remote network control unit that responds to the destination address received from the host data interface; and

medium analysis unit that receives a quality profile message from a sounding unit in the remote network control unit and establishes a modulation density level for each of a plurality of carriers comprising the sounding message conveyed by the PHY/MAC to the remote PHY/MAC either wirelessly or by physical medium.

17. The networking control unit of claim 16 wherein the medium analysis unit receives an impairment identification message from the sounding unit in the remote network control unit and

if the impairment identified in the impairment identification message is a wide-band interferer, the medium analysis unit:

causes the sounding unit to send a sounding message to the PHY/MAC so as to convey the sounding message to the PHY/MAC in a remote network control unit that responds to the destination address received from the host data interface; and

receives a quality profile message from a sounding unit in the remote network control unit and establishes a modulation density level for each of a plurality of carriers comprising the sounding message conveyed by the PHY/MAC to the remote PHY/MAC either wirelessly or by physical medium and

if the impairment identified in the impairment identification message is a narrow-band interferer, the medium analysis unit;

sets to nil the established modulation density for the carrier frequencies imposed upon by the narrow-band interferer as unavailable.

18. The networking control unit of claim 12 wherein the resource allocation tracking unit comprises:

beacon reception unit that receives allocation messages from the PHY/MAC that indicate what portions of the spectrum are allocated and in what time-slots the allocations are valid; and

table management unit that;

creates an allocation profile table from a first received allocation message and updates said table as subsequent allocation messages are received from the PHY/MAC and wherein the allocation profile table indicates the allocation of spectrum and time-slots.

19. The networking control unit of claim 12 wherein transfer function profile comprises an plurality of modulation densities for each carrier and wherein the modulation unit receives a required bandwidth indicator from the host data interface and selects carriers from those identified in the resource allocation profile as being available and determines the number of carriers that are required to accommodate the required bandwidth by consulting the established modulation density for each carrier.

20. The networking control unit of claim 12 wherein the resource usage broadcast unit periodically creates a beacon message that comprises an enumeration of the frequencies of the set of carriers generated by the modulation unit.

21. The networking control unit of claim 20 wherein the beacon message further comprises additional resource allocation information stored in the resource allocation profile generated by the resource allocation tracking unit.

22. A method for establishing a circuit connection over a network comprising the steps of:

determining a resource allocation profile of existing frequency and time slot allocations in use on a medium;

selecting a portion of the available frequencies and time slots from the resource allocation profile for transmitting information to a destination node; and

communicating the selection of frequencies and time slots to other nodes attached to the medium.

23. The method of claim 22 wherein the step of determining a resource allocation profile of existing frequency and time slot allocations comprises forming a frequency and time slot allocation profile based on one of either of:

a frequency and time slot allocation profile received from a node attached to a medium,

an individual frequency and time slot reservation message received from a node attached to a medium,

a pseudo-composite frequency and time slot profile received from a node attached to a medium and

observations of the usage of a medium by other nodes attached thereto.

24. The method of claim 22 wherein the step of selecting a portion of the available frequencies and time slots comprises selecting a portion of the available frequencies and time slots in order to minimize the amount of resources required to accomplish a desired throughput.

25. The method of claim 22 wherein the step of selecting a portion of the available frequencies and time slots comprises selecting a portion of the available frequencies and time slots in order to minimize the amount of resources required to accomplish a desired quality of service.

26. The method of claim 22 wherein the step of selecting a portion of the available frequencies and time slots comprises:

determining the channel quality profile of a medium connecting a source node to a destination node; and

selecting a portion of the available frequencies and time slots based on the channel quality profile.

27. The method of claim 26 wherein the step of determining the channel quality profile of a medium comprises one of either

determining the attenuation of the channel at each available frequency,

determining the noise at each available frequency,

determining the interference at each available frequency,

determining the signal to noise ratio at each available frequency,

determining the variation of the attenuation of the channel with time at each available frequency,

determining the variation of the attenuation of the channel with frequency at each available frequency,

determining the variation of the phase response of the channel with time at each available frequency and

determining the variation of the phase response of the channel with frequency at each available frequency.

28. The method of claim 26 wherein the step of determining the channel quality profile of a medium comprises:

sending a sounding signal from a source node to a destination node; and

determining the quality of the sounding signal arriving at the destination node at each frequency and time slot.

29. The method of claim 26 wherein the step of selecting a portion of the available frequencies and time slots comprises the steps of:

determining the throughput required to support the data rate requirement of an application that sources data;

determining the most effective modulation type and density at each frequency according to the channel quality profile; and

selecting a set of frequencies, modulation types and densities for each frequency to support the throughput requirements of the application.

30. The method of claim 29 wherein the step of determining the throughput required to support the data rate requirement of an application comprises receiving a required data bandwidth indication from the source node.

31. The method of claim 29 wherein the step of determining the most effective modulation type and density comprises the step of determining the densest modulation that can be supported at each frequency at a desired error performance at each time slot based on the channel quality determined at that frequency.

32. The method of claim 29 wherein the step of selecting a set of frequencies, modulation types and densities for each frequency comprises the step of selecting a set of frequencies and modulation types that provide the throughput needed by the application with the minimum resource requirements.

33. The method of claim 22 wherein the step of communicating the selection of frequencies and time slots to other nodes attached to the medium comprises the step of transmitting a broadcast message containing information describing the selected channel resources.

34. The method of claim 22 wherein the step of communicating the selection of frequencies and time slots to other nodes attached to the medium comprises the steps of:

transmitting information about the selected frequencies and time slots to a first node; and

retransmitting the information about the selected frequencies and time slots from the first node to other nodes attached to the medium.

35. The method of claim 26 further comprising the steps of:

re-determining the channel quality profile of the medium;

re-determining the resource allocation profile;

evaluating the suitability of existing frequency and time slot allocations in light of any changes in the channel quality profile and the resource allocation profile;

selecting a new portion of the available frequencies and time slots for transmitting information to the destination node if the efficiency of resource allocation in the resource allocation profile may be improved by a predetermined amount; and

communicating the new selection of frequencies and time slots to other nodes attached to the medium.

36. A network node comprising:

resource allocation profile unit capable of determining existing frequency and time slot allocations on a medium;

reservation manager capable of selecting a portion of available frequencies and time slots according to information received from the resource allocation profile unit; and

medium access control unit capable of conveying an indicator of selected frequencies and time slots to the medium.

37. The network node of claim 36 wherein the resource allocation profile unit comprises:

profile module selected from the group;

profile receiver capable of receiving a frequency and time slot allocation profile from the medium,

reservation message receiver capable of receiving an individual frequency and time slot reservation message from the medium, pseudo-composite frequency and time slot receiver capable of receiving a pseudo-composite frequency and time slot allocation profile from the medium and

observation module capable of generating a reservation indicator by observing activity on the medium; and

allocation processor that stores an allocation profile in an allocation profile memory according to an indicator received from the profile module.

38. The network node of claim 36 wherein the reservation management unit comprises a minimization unit that minimizes the amount of resources selected to accomplish a required throughput.

39. The network node of claim 36 wherein the reservation management unit comprises a minimization unit that minimizes the amount of resources selected to accomplish a required quality of service.

40. The network node of claim 36 wherein the reservation management unit comprises:

channel quality unit capable of determining the quality of a medium between a source node and a destination node; and

resource selector capable of selecting resources from a list of available resources received from the resource allocation profile unit according to a channel quality indicator received from the channel quality unit.

41. The network node of claim 40 wherein the channel quality unit is selected from the group consisting of:

attenuation unit capable of determining the attenuation of the medium at each available frequency,

noise unit capable of determining the noise present on the medium at each available frequency,

interference unit capable of determining the interference present on the medium at each available frequency,

signal-to-noise unit capable of determining the signal-to-noise ration on the medium at each available frequency,

attenuation versus time variance unit capable of determining the variation of attenuation over time of the medium for each available frequency,

attenuation versus frequency variance unit capable of determining the variation of attenuation over frequency of the medium for each available frequency,

phase versus time variance unit capable of determining the variation of phase response over time of the medium for each available frequency and phase versus frequency variance unit capable of determining the variation of phase response over frequency of the medium for each available frequency.

42. The network node of claim 40 wherein the channel quality unit comprises a sounding unit capable of sending a sounding message from a source node to a destination node and receiving an indicator of sounding message quality from the destination node.

43. The network node of claim 40 wherein reservation management unit comprises:

A throughput determination unit capable of determining the throughput required by an application that will transfer data on the network,

A modulation density evaluator capable of determining the most effective modulation type and density at each frequency according to the channel quality profile, and

a resource selector capable of selecting resources according to the most effective modulation type and density and the required throughput.

44. The network node of claim 40 wherein the throughput determination unit is capable of receiving a required data bandwidth indicator transmitted by a source node.

45. The network node of claim 40 wherein the modulation density evaluator is capable of accepting a desired error performance and channel quality profile, and based on these determines the densest modulation that can be supported at each frequency and time slot.

46. The network node of claim 40 wherein the resource selector is capable of selecting a set of frequencies and time slots that provide the throughput required by the application with the minimum resource requirements.

47. The network node of claim 36 wherein the medium access control unit is capable of conveying a broadcast message containing information describing the selected channel resources.

48. The network node of claim 36 wherein the medium access control unit is capable of conveying information about the selected frequencies and time slots to a first node, wherein the medium access control unit is capable of re-transmitting the information about the selected frequencies and time slots to other nodes on the medium.