Multi-level information mapping system and method

• US 6,404,755 B1
• Filed: 06/07/1999
• Issued: 06/11/2002
• Est. Priority Date: 11/07/1996
• Status: Expired due to Term

• Current Assignee: BWA Technology Incorporated
• Original Assignee: Harris Broadband Wireless Access Incorporated
• Inventors: Schafer, David C.
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): PHAN, MAN U
• Application Number:
  US09/327,787
• Time in Patent Office: 1,100 Days
• Field of Search: 370/338, 370/442, 370/465, 370/342, 370/347, 370/395, 370/538, 370/206, 370/207, 370/490, 370/491, 375/224, 375/227, 375/261, 375/221, 375/225, 375/257, 375/262
• US Class Current: 370/338
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 27/0008 arrangements for allowing a transmitter or receiver to use more than one type of modulation negotiating modulation type for two-way transmission paths H04L5/1453
• CPC Class Codes: H04W 40/02 Communication route or path selection, e.g. power-based or shortest path routing
• CPC Class Codes: H04W 88/02 Terminal devices
• CPC Class Codes: H04W 88/14 Backbone network devices
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A system and method for providing adjustable levels of information density in a communicated data stream in response to monitored communication link conditions is disclosed. In a preferred embodiment the data stream is a time division multiple access data stream providing data communication to a plurality of geographically separated systems. The information density of time bursts associated with each such system may be independently adjusted according to the disclosed invention based upon each such system'"'"'s link conditions. A preferred embodiment of the invention utilizes a mapping technique in order to utilize a modulator adjusted for a high level information density to emulate lower level information density transmission.

Claims

1. A system for providing dynamically adjustable information density over a communication link, wherein said communication link is adapted so as to provide a minimum level of link availability, said system comprising:

a monitor in communication with said link adapted to monitor an attribute of said link wherein said monitored attribute is selected from the group consisting of;

an error rate of a receive signal;

a signal to noise ratio;

a signal to noise ratio estimate;

a signal to interference ratio; and

a power level of a receive signal;

a controller in communication with said monitor adapted to accept information therefrom and to determine an optimum information density for information communication via said link at least in part as a function of said monitored attribute; and

a manipulator in communication with said controller adapted to accept information therefrom and to adjust equipment communicating via said link to said optimum information density.

2. The system of claim 1, wherein said equipment adjusted by said manipulator includes transmitter equipment to cause said transmitter equipment to adjust the information density of transmitted information from a first level to a second level of a plurality of predefined information density levels.

11. The system of claim 1, wherein said a minimum level of link availability of said communication link is associated with a minimum data rate, and wherein adjustment of said information density provides a data rate in excess of said minimum data rate.

12. The system of claim 1, wherein said minimum level of link availability of said communication link is associated with a minimum service tier, and wherein said adjustment of said information density provides a service tier in excess of said minimum service tier.

13. The system of claim 1, wherein information communicated over said communication link is at a constant baud rate, and wherein adjustment of said adjustable information density includes changing from one modulation level to another modulation level of a multi-level modulation format at said constant baud rate.

14. The system of claim 13, wherein said multi-level modulation format is a QAM format.

15. The system of claim 13, wherein said multi-level modulation format is a PSK format.

16. The system of claim 13, wherein said multi-level modulation format is a FSK format.

17. The system of claim 13, wherein said multi-level modulation format is an ASK format.

18. The system of claim 13, wherein said multi-level modulation format is a CAP format.

19. The system of claim 1, wherein said link includes a wireless communication link.

20. The system of claim 19, wherein said link provides a TDMA channel including a plurality of time slots, wherein ones of said time slots may provide a different information density.

21. The system of claim 20, wherein said time slots of said TD mA channel include a payload portion and a control channel portion, wherein the information density of said payload portion is adjustable from time slot to time slot and the information density of said control channel portion is persistently held at a predetermined information density.

22. The system of claim 21, wherein said predetermined density is a minimum density determined to provide highly reliable communication via said communication link.

3. A system for providing dynamically adjustable information density over a communication link, wherein said communication link is adapted so as to provide a minimum level of link availability, said system comprising:

a monitor in communication with said link adapted to monitor an attribute of said link;

a controller in communication with said monitor adapted to accept information therefrom and to determine an optimum information density for information communication via said link at least in part as a function of said monitored attribute; and

a manipulator in communication with said controller adapted to accept information therefrom and to adjust equipment communicating via said link to said optimum information density,

wherein said equipment includes transmitter equipment to adjust the information density of transmitted information from a first level to a second level of a plurality of predefined information density levels, and

wherein said transmitter equipment comprises mapper circuitry adapted to accept information at a plurality of densities and output said accepted information at a predetermined density irrespective of the density of said accepted information, wherein said output information is associated with a signal point of said predetermined density corresponding to a signal point of said density of said accepted information associated with said accepted information.

4. The system of claim 3, wherein said transmitter equipment persistently operates in a high order information density mode, and wherein said transmitter equipment operates to emulate a lower order information density mode as a function of said accepted information being properly mapped to said high order information density.

5. The system of claim 3, wherein said predetermined density is a maximum density determined to provide acceptable communication via said communication link.

6. A system for providing dynamically adjustable information density over a communication link, wherein said communication link is adapted so as to provide a minimum level of link availability, said system comprising:

a monitor in communication with said link adapted to monitor an attribute of said link;

a controller in communication with said monitor adapted to accept information therefrom and to determine an optimum information density for information communication via said link at least in part as a function of said monitored attribute; and

a manipulator in communication with said controller adapted to accept information therefrom and to adjust equipment communicating via said link to said optimum information density,

wherein said equipment includes transmitter equipment to adjust the information density of transmitted information from a first level to a second level of a plurality of predefined information density levels, and

wherein said equipment adjusted by said manipulator includes receiver equipment to cause said receiver equipment to adjust for the reception of information from a first level to a second level of a plurality of predefined information density levels.

7. The system of claim 6, further comprising:

a control channel defined in said communication link, wherein said adjustment of receiver equipment by said manipulator includes the use of information transmitted via said control channel.

8. The system of claim 7, wherein said receiver equipment comprises:

mapper circuitry adapted to accept information at a plurality of densities and output said accepted information at a predetermined density irrespective of the density of said accepted information, wherein said output information is associated with a signal point of said predetermined density corresponding to a signal point of said density of said accepted information associated with said accepted information.

9. The system of claim 8, wherein said receiver equipment operates to emulate a low order information density mode at least with respect to said control channel information as a function of said accepted information being properly mapped to said low order information density.

10. The system of claim 8, wherein said predetermined density is a minimum density determined to provide highly reliable communication via said communication link.

23. A system for providing dynamically adjustable information density over a wireless communication link, wherein said communication link is adapted so as to provide a minimum level of link availability, said system comprising:

a monitor in communication with said link adapted to monitor an attribute of said link;

a controller in communication with said monitor adapted to accept information therefrom and to determine an optimum information density for information communication via said link at least in part as a function of said monitored attribute; and

a manipulator in communication with said controller adapted to accept information therefrom and to adjust equipment communicating via said link to said optimum information density,

wherein said wireless communication link is adjusted to provide said minimum link availability during the occurrence of an expected time varying event.

24. The system of claim 23, wherein said wireless communication link is a microwave link and said adjustment of provide said minimum link availability includes a transmit power to compensated for a maximum expected rain fade.

25. A system for providing dynamically adjustable information density over a wireless communication link, wherein said communication link is adapted so as to provide a minimum level of link availability, said system comprising:

a monitor in communication with said link adapted to monitor an attribute of said link;

a controller in communication with said monitor adapted to accept information therefrom and to determine an optimum information density for information communication via said link at least in part as a function of said monitored attribute; and

a manipulator in communication with said controller adapted to accept information therefrom and to adjust equipment communicating via said link to said optimum information density,

wherein said link provides a TDMA channel including a plurality of variable duration time slots.

26. The system of claim 25, wherein a duration a time slot of said variable duration time slots is adjusted to provide a desired payload capacity.

27. The system of claim 26, wherein adjustment of said duration of said time slot is in association with adjustment for said optimum information density.

28. A system for optimizing in real time an information density of a plurality of information densities utilized in information communication via a link, said system comprising:

a means for maintaining a desired level of link availability including establishing at least one communication parameter commensurate with said desired level of link availability;

means for monitoring in real time at least one attribute of said link;

means for determining, at least in part as a function of said monitored at least one attribute, an optimum information density of said plurality of information densities for information communication via said link, wherein utilization of said determined optimum information density is consistent with said communication parameter under link conditions associated with said monitored at least one attribute; and

means for adjusting an information density of data transmitted through said link to said optimum information density,

wherein said at least one link parameter is selected from the group consisting of;

a transmit power level;

a receive power level;

a signal to noise ratio estimate;

a signal to noise ratio; and

a communication quality indication.

30. The system of claim 28 wherein said monitoring means comprises:

means for monitoring in real time said at least one attribute in an uplink portion of said link; and

means for monitoring in real time said at least one attribute in a downlink portion of said link.

31. The system of claim 28 wherein said determining means comprises:

means for correlating a particular information density with said monitored at least one attribute.

32. The system of claim 31, wherein said correlating means references a database storing historical information with respect to information densities which provide at least said desired level of link availability under conditions associated with said monitored at least one attribute.

33. The system of claim 28 wherein said determining means comprises:

means for comparing said monitored at least one attribute to information with respect to said at least one communication parameter, wherein said optimum information density is determined as a function of the comparison.

29. A system for optimizing in real time an information density of a plurality of information densities utilized in information communication via a link, said system comprising:

a means for maintaining a desired level of link availability including establishing at least one communication parameter commensurate with said desired level of link availability;

means for monitoring in real time at least one attribute of said link;

means for determining, at least in part as a function of said monitored at least one attribute, an optimum information density of said plurality of information densities for information communication via said link, wherein utilization of said determined optimum information density is consistent with said communication parameter under link conditions associated with said monitored at least one attribute; and

means for adjusting an information density of data transmitted through said link to said optimum information density,

wherein said monitored at least one attribute is selected from the group consisting of;

a receive power level;

a signal to noise ratio estimate;

a signal to noise ratio; and

a communication quality indication.

34. The system of claim 29 wherein said adjusting means comprises:

means for emulating a selected information density without adjusting a preselected level at which information is modulated for transmission.

37. The system of claim 29 further comprising:

means for controlling receiving equipment in accordance with adjustment of said information density by said adjusting means.

38. The system of claim 37, wherein said controlling means comprises:

means for providing a control signal within said link, wherein receiver equipment utilizes said control signal to detect an adjustment of information density.

39. The system of claim 38, wherein said control signal is provided at a particular information density irrespective of said optimum information density of data transmitted through said link.

40. The system of claim 39, wherein said controlling means comprises:

means for mapping received data, regardless of an information density bit stream in which it is demodulated, into a bit stream associated with said preselected information density.

35. A system for optimizing in real time an information density of a plurality of information densities utilized in information communication via a link, said system comprising:

a means for maintaining a desired level of link availability including establishing at least one communication parameter commensurate with said desired level of link availability;

means for monitoring in real time at least one attribute of said link;

means for determining, at least in part as a function of said monitored at least one attribute, an optimum information density of said plurality of information densities for information communication via said link, wherein utilization of said determined optimum information density is consistent with said communication parameter under link conditions associated with said monitored at least one attribute; and

means for adjusting an information density of data transmitted through said link to said optimum information density,

wherein said adjusting means comprises;

means for emulating a selected information density without adjusting a preselected level at which information is modulated for transmission, and

wherein said plurality of information densities are various QAM rates, and said mapping means maps data associated with lower order QAM rates to higher order QAM rates such that a same signal point is modulated from said mapped data at said higher order QAM as would be modulated from said input data at said lower order QAM rates.

36. The system of claim 35, wherein said plurality of information densities are various QAM rates, and said mapping means maps data associated with lower order QAM rates to a higher order QAM rate such that a same signal point is modulated from said mapped data at said higher order QAM as would be modulated from said input data at said lower order QAM rates.

41. A system for optimizing in real time an information density of a plurality of information densities utilized in information communication via a link, said system comprising:

a means for maintaining a desired level of link availability including establishing at least one communication parameter commensurate with said desired level of link availability;

means for monitoring in real time at least one attribute of said link;

means for determining, at least in part as a function of said monitored at least one attribute, an optimum information density of said plurality of information densities for information communication via said link, wherein utilization of said determined optimum information density is consistent with said communication parameter under link conditions associated with said monitored at least one attribute; and

means for adjusting an information density of data transmitted through said link to said optimum information density,

wherein said system is deployed in a point to multi-point microwave communication system including a communication hub in TDMA communication with a plurality of communication nodes, wherein said link is associated with a particular node of said plurality of communication nodes and said optimum information density is determined for a time slot of said TDMA communication assigned to said link independent of other time slots of said TDMA communication assigned to links associated with other nodes of said plurality of nodes.

42. A system for optimizing in real time an information density of a plurality of information densities utilized in information communication via a link, said system comprising:

a means for maintaining a desired level of link availability including establishing at least one communication parameter commensurate with said desired level of link availability;

means for monitoring in real time at least one attribute of said link;

means for determining, at least in part as a function of said monitored at least one attribute, an optimum information density of said plurality of information densities for information communication via said link, wherein utilization of said determined optimum information density is consistent with said communication parameter under link conditions associated with said monitored at least one attribute; and

means for adjusting an information density of data transmitted through said link to said optimum information density,

wherein said link provides a plurality of variable duration time slots adjustable to provide desired payload capacity.

43. A method for optimizing in real time an information density of a data payload utilized in information communication via a link, wherein said information communication includes said data payload and control data, said method comprising the steps of:

establishing at least one communication parameter to maintain a desired level of link availability;

monitoring in real time at least one attribute of said link;

determining, at least in part as a function of said monitored at least one attribute, an optimum information density for information communication of said data payload via said link, wherein utilization of said determined optimum information density is consistent with said communication parameter under link conditions associated with said monitored at least one attribute; and

adjusting an information density of said payload data transmitted through said link to said optimum information density,

wherein said at least one link parameter is selected from the group consisting of;

a transmit power level;

a receive power level;

a signal to noise ratio estimate;

a signal to noise ratio; and

a communication quality indication.

45. The method of claim 43 wherein said monitoring step comprises the steps of:

monitoring in real time said at least one attribute in an uplink portion of said link; and

monitoring in real time said at least one attribute in a downlink portion of said link.

44. A method for optimizing in real time an information density of a data payload utilized in information communication via a link, wherein said information communication includes said data payload and control data, said method comprising the steps of:

establishing at least one communication parameter to maintain a desired level of link availability;

monitoring in real time at least one attribute of said link;

determining, at least in part as a function of said monitored at least one attribute, an optimum information density for information communication of said data payload via said link, wherein utilization of said determined optimum information density is consistent with said communication parameter under link conditions associated with said monitored at least one attribute; and

adjusting an information density of said payload data transmitted through said link to said optimum information density,

wherein said monitored at least one attribute is selected from the group consisting of;

a receive power level;

a signal to noise ratio estimate;

a signal to noise ratio; and

a communication quality indication.

46. The method of claim 44 wherein said adjusting step comprises the step of:

emulating a selected information density without adjusting a preselected level at which information is modulated for transmission.

50. The method of claim 44 further comprising the step of:

controlling receiving equipment in accordance with said adjusting step.

51. The method of claim 50, wherein said controlling step comprises the step of:

providing information within said control data, wherein receiver equipment utilizes said control information to detect an adjustment of information density in said data payload.

52. The method of claim 51, wherein said controlling means comprises:

mapping received control data, regardless of an information density bit stream in which it is demodulated, into a bit stream associated with a preselected information density.

47. A method for optimizing in real time an information density of a data payload utilized in information communication via a link, wherein said information communication includes said data payload and control data, said method comprising the steps of:

establishing at least one communication parameter to maintain a desired level of link availability;

monitoring in real time at least one attribute of said link;

determining, at least in part as a function of said monitored at least one attribute, an optimum information density for information communication of said data payload via said link, wherein utilization of said determined optimum information density is consistent with said communication parameter under link conditions associated with said monitored at least one attribute; and

adjusting an information density of said payload data transmitted through said link to said optimum information density,

wherein said adjusting step comprises the step of;

emulating a selected information density without adjusting a preselected level at which information is modulated for transmission, and

wherein said emulating step comprises the step of;

mapping input data associated with said data payload presented in a bit stream of a first magnitude into a bit stream of a second magnitude associated with said preselected level at which information is modulated for transmission.

48. The method of claim 47, wherein said emulating step comprises the step of:

mapping input data associated with said control data presented in a bit stream of a third magnitude into a bit stream of said second magnitude associated with said preselected level at which information is modulated for transmission thereby emulating two information densities within a single transmission.

49. The method of claims 48, wherein said first bit stream is selected from the group consisting of 2 bits, 4 bits, 6 bits, and 8 bits, and wherein said second bit stream is 8 bits, and wherein said third bit stream is 2 bits.

53. A method for optimizing in real time an information density of a data payload utilized in information communication via a link, wherein said information communication includes said data payload and control data, said method comprising the steps of:

establishing at least one communication parameter to maintain a desired level of link availability;

monitoring in real time at least one attribute of said link;

determining, at least in part as a function of said monitored at least one attribute, an optimum information density for information communication of said data payload via said link, wherein utilization of said determined optimum information density is consistent with said communication parameter under link conditions associated with said monitored at least one attribute; and

adjusting an information density of said payload data transmitted through said link to said optimum information density,

wherein said adjusting step comprises the step of;

varying a duration of a payload time slot in cooperation with adjusting said information density to provide a desired data throughput.