Systems and methods for orthogonal frequency divisional multiplexing

• US 8,547,824 B2
• Filed: 04/11/2012
• Issued: 10/01/2013
• Est. Priority Date: 09/26/1994
• Status: Expired due to Fees

• Current Assignee: HTC Corporation
• Original Assignee: HTC Corporation
• Inventors: Brede, Jeffrey, Tucker, Thomas C., Nelson, Calvin G., Wadman, Mark S., Hall, Joe, Samant, Niranjan R., Kirscht, Robert J., Logajan, John M., Chiappetta, Joseph F., Herrmann, James J., Boualouang, Somvay, Sarnikowski, Scott, Fort, Michael J., Lou, Heng, Dapper, Mark J., Buska, Steven P., Elpers, Mark D., Geile, Michael J., Solum, Jeff, Downs, Matt, Hill, Terrance J., Enfield, Debra Lee, Ferris, Tammy, Roberts, Harold A., Berg, Darrell, Opoczynski, Adam, Anderson, Brian D., Smigelski, Thomas, Russell, David S.
• Primary Examiner(s): JAIN, RAJ K
• Application Number:
  US13/444,638
• Publication Number:
  US 20120195184A1
• Time in Patent Office: 538 Days
• Field of Search: None
• US Class Current: 370/210
• CPC Class Codes: G06F 17/14 Fourier, Walsh or analogous domain transformations , e.g. Laplace, Hilbert, Karhunen-Loeve, transforms for correlation function computation G06F17/156; spectrum analysers G01R23/16
• CPC Class Codes: G06F 17/142 Fast Fourier transforms, e.g. using a Cooley-Tukey type algorithm
• CPC Class Codes: H03M 13/1515 Reed-Solomon codes
• CPC Class Codes: H03M 13/356 Unequal error protection [UEP]
• CPC Class Codes: H04B 10/272 Star-type networks or tree-type networks
• CPC Class Codes: H04H 20/69 Optical systems
• CPC Class Codes: H04H 20/77 using carrier waves
• CPC Class Codes: H04H 20/78 CATV [Community Antenna Television] systems
• CPC Class Codes: H04H 20/79 using downlink of the CATV systems, e.g. audio broadcast via CATV network
• CPC Class Codes: H04H 20/80 having frequencies in two or more frequency bands, e.g. medium wave and VHF
• CPC Class Codes: H04H 60/11 Arrangements for counter-measures when a portion of broadcast information is unavailable
• CPC Class Codes: H04H 60/86 accessed over CATV networks
• CPC Class Codes: H04H 60/96 CATV systems for accessing the Internet H04H60/86
• CPC Class Codes: H04H 60/97 using uplink of the CATV systems
• CPC Class Codes: H04J 14/0298 with sub-carrier multiplexing [SCM]
• CPC Class Codes: H04J 3/14 Monitoring arrangements for SDH/SONET rings H04J3/085
• CPC Class Codes: H04K 1/00 Secret communication
• CPC Class Codes: H04K 3/226 Selection of non-jammed channel for communication spectrum sharing arrangements H04W16/14; selection of wireless resources by user or terminal H04W72/02
• CPC Class Codes: H04K 3/255 based on redundancy of transmitted data, transmission path or transmitting source
• CPC Class Codes: H04L 1/004 by using forward error control H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00
• CPC Class Codes: H04L 1/0045 : Arrangements at the receiver end
• CPC Class Codes: H04L 1/0057 : Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/0071 : Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/24 : Testing correct operation
• CPC Class Codes: H04L 12/10 : Current supply arrangements
• CPC Class Codes: H04L 12/12 : Arrangements for remote connection or disconnection of substations or of equipment thereof
• CPC Class Codes: H04L 12/2801 : Broadband local area networks
• CPC Class Codes: H04L 12/44 : Star or tree networks
• CPC Class Codes: H04L 2001/0093 : Point-to-multipoint
• CPC Class Codes: H04L 2027/0036 : using a recovered symbol clock
• CPC Class Codes: H04L 2027/0057 : quadrature phase
• CPC Class Codes: H04L 2027/0067 : Phase error detectors
• CPC Class Codes: H04L 25/03866 : using scrambling
• CPC Class Codes: H04L 27/2601 : Multicarrier modulation systems
• CPC Class Codes: H04L 27/2614 : Peak power aspects
• CPC Class Codes: H04L 27/2631 : with polyphase implementation
• CPC Class Codes: H04L 27/2634 : Inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators in combination with other circuits for modulation
• CPC Class Codes: H04L 27/2647 : Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 27/2652 : with polyphase implementation
• CPC Class Codes: H04L 27/26524 : Fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators in combination with other circuits for demodulation
• CPC Class Codes: H04L 27/2654 : Filtering per subcarrier, e.g. filterbank multicarrier [FBMC]
• CPC Class Codes: H04L 27/2655 : Synchronisation arrangements
• CPC Class Codes: H04L 27/2657 : Carrier synchronisation
• CPC Class Codes: H04L 27/2662 : Symbol synchronisation
• CPC Class Codes: H04L 27/34 : Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
• CPC Class Codes: H04L 41/0213 : Standardised network management protocols, e.g. simple network management protocol [SNMP]
• CPC Class Codes: H04L 41/064 : involving time analysis
• CPC Class Codes: H04L 41/0896 : Bandwidth or capacity management, i.e. automatically increasing or decreasing capacities flow or congestion control using dynamic resource allocation, e.g. in-call renegotiation, H04L47/76
• CPC Class Codes: H04L 43/00 : Arrangements for monitoring or testing data switching networks
• CPC Class Codes: H04L 43/022 : by sampling
• CPC Class Codes: H04L 43/067 : using time frame reporting
• CPC Class Codes: H04L 43/0811 : by checking connectivity
• CPC Class Codes: H04L 43/0817 : by checking functioning
• CPC Class Codes: H04L 43/0823 : Errors, e.g. transmission errors
• CPC Class Codes: H04L 43/0829 : Packet loss
• CPC Class Codes: H04L 43/0847 : Transmission error
• CPC Class Codes: H04L 43/0852 : Delays
• CPC Class Codes: H04L 43/0858 : One way delays
• CPC Class Codes: H04L 43/0864 : Round trip delays
• CPC Class Codes: H04L 43/0882 : Utilisation of link capacity
• CPC Class Codes: H04L 43/16 : Threshold monitoring
• CPC Class Codes: H04L 5/0007 : the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0037 : Inter-user or inter-terminal allocation
• CPC Class Codes: H04L 5/0044 : allocation of payload
• CPC Class Codes: H04L 5/023 : Multiplexing of multicarrier modulation signals multicarrier modulation H04L27/2601
• CPC Class Codes: H04L 5/14 : Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04L 5/143 : for modulated signals H04L5/1469 takes precedence
• CPC Class Codes: H04L 5/1484 : operating bytewise
• CPC Class Codes: H04M 7/006 : Networks other than PSTN/ISDN providing telephone service, e.g. Voice over Internet Protocol (VoIP) , including next generation networks with a packet-switched transport layer H04L65/00 takes precedence; aspects not specific to the type of network H04M3/00; special services in those networks H04M3/42
• CPC Class Codes: H04M 9/027 : Frequency division multiplex systems
• CPC Class Codes: H04N 21/2221 : being a cable television head-end CATV in broadcast systems H04H20/78
• CPC Class Codes: H04N 21/2383 : Channel coding or modulation of digital bit-stream, e.g. QPSK modulation arrangements for detecting or preventing errors in the information received by adapting the channel coding H04L1/0009; analogue front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/2385 : Channel allocation H04N21/266 takes precedence; Bandwidth allocation H04N21/24 takes precedence ; allocation of channels according to the instantaneous demands of the users in time-division multiplex systems H04J3/1682; admission control, resource allocation in open networks H04L12/5692; arrangements for maintenance or administration in data switching networks involving bandwidth and capacity management H04L41/0896; negotiating bandwidth in wireless networks H04W28/16
• CPC Class Codes: H04N 21/2402 : Monitoring of the downstream path of the transmission network, e.g. bandwidth available traffic monitoring in data switching networks H04L43/00; monitoring data switching networks utilization H04L43/0876
• CPC Class Codes: H04N 21/4382 : Demodulation or channel decoding, e.g. QPSK demodulation analog front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/6118 : involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 21/6137 : involving transmission via a telephone network, e.g. POTS
• CPC Class Codes: H04N 21/6168 : involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 7/17309 : Transmission or handling of upstream communications
• CPC Class Codes: H04N 7/22 : Adaptations for optical transmission
• CPC Class Codes: H04W 24/00 : Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 24/08 : Testing, supervising or monitoring using real traffic
• CPC Class Codes: Y02D 30/50 : in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

Systems and methods for orthogonal frequency division multiplexing are provided. In one embodiment, a multi-carrier modem comprises: a transmitter configured to modulate symbols onto at least one of a plurality of the spectrally overlapping carrier signals; a processor coupled to the transmitter, wherein the processor outputs data for transmission by the transmitter, wherein the processor applies an inverse Fourier transform to the data transmitted by the transmitter; the processor modulating a first carrier of the plurality of spectrally overlapping carrier signals based on a first modulation scheme while modulating a second carrier of the plurality of spectrally overlapping carrier signals based on a second modulation scheme.

Claims

1. A multi-carrier modem, the modem comprising:

a transmitter configured to modulate symbols onto at least one of a plurality of the spectrally overlapping carrier signals;

a processor coupled to the transmitter, wherein the processor outputs data for transmission by the transmitter, wherein the processor applies an inverse Fourier transform to the data transmitted by the transmitter;

the transmitter modulating a first carrier of the plurality of spectrally overlapping carrier signals based on a first modulation scheme while modulating a second carrier of the plurality of spectrally overlapping carrier signals based on a second modulation scheme.

2. The modem of claim 1, the controller further programmed to instruct the transmitter to transmit an adjustment instruction modulated using the inverse Fourier transform to the at least one of a plurality of remote units, the adjustment instruction instructing the at least one of the plurality of remote units to vary a phase of transmissions transmitted from the at least one of the plurality of remote units.

3. The modem of claim 1, wherein the inverse Fourier transform is based on one of an inverse Fast Fourier Transform (FFT) and an inverse Discrete Fourier Transform (DFT).

4. A method for quality based assessments of orthogonal channels for remote service units of an OFDM based multiple access system, the method comprising:

monitoring a subset of orthogonal carriers within an OFDM waveform associated with at least one communication channel, wherein the subset of orthogonal carriers comprises less than all of the orthogonal carriers within the OFDM waveform;

determining a quality measurement for the subset of orthogonal carriers;

communicating a notification message regarding the quality measurement for the subset of orthogonal carriers; and

adjusting a frequency of upstream carriers of the OFDM waveform to maintain orthogonality within the OFDM waveform.

5. The method of claim 4, further comprising:

maintaining quality statistics for the subset of orthogonal carriers in a memory.

6. The method of claim 5, wherein the quality statistics include either a bit error rate or a signal-to-noise ratio.

7. The method of claim 4, further wherein the subset of orthogonal carriers comprises more than one orthogonal carrier.

8. The method of claim 4, wherein the quality information includes a quality statistic.

9. The method of claim 4, further comprising:

communicating data over the at least one communication channel based on whether the quality measurement for the subset of orthogonal carriers satisfies a quality standard.

10. The method of claim 4, wherein the subset of orthogonal carriers are noncontiguous sets of orthogonal carriers within the OFDM waveform.

11. The method of claim 4, further comprising:

comparing the quality measurement for the subset of orthogonal carriers against predetermined quality standards.

12. The method of claim 4, further comprising:

determining when the quality measurements for the subset of orthogonal carriers exceeds allowable limits.

13. The method of claim 4, wherein the OFDM waveform is a wireless waveform.

14. A method for quality based allocation of orthogonal channels for remote service units of an OFDM based multiple access system, the method comprising:

determining a channel quality measurement for a first portion of an OFDM waveform, said first portion comprising less than all the payload bearing orthogonal tones within the waveform;

determining a channel quality measurement for a second portion of the OFDM waveform different than the first portion, said second portion comprising less than all the payload bearing orthogonal tones within the waveform; and

receiving an allocation of only a portion of upstream orthogonal tones, said allocation based at least in part on the channel quality measurements for said first and second portions;

receiving frequency and timing adjustment information for maintaining orthogonality of the upstream orthogonal tones.

15. The method of claim 14, wherein the payload bearing orthogonal tones are always payload bearing.

16. The method of claim 14, further comprising:

receiving timing adjustment information for making timing adjustments to improve orthogonality of signals transmitted using the allocated tones.

17. The method of claim 14, further comprising:

notifying a channel allocator in the event one of said channel quality measurements indicates a corrupted channel.

18. The method of claim 14, wherein the channel quality measurement includes at least one of a signal-to-noise ratio and a bit error rate.

19. The method of claim 14, further comprises comparing the channel quality measurement for the first portion to the channel quality measurement for the second portion.

20. The method of claim 14, further comprising comparing the channel quality measurement for the first portion to a quality standard.

21. A remote service unit for a multiple access OFDM communication system, the remote service unit comprising:

a transceiver for receiving an OFDM waveform, the OFDM waveform having references signals distributed throughout, the references signals for adjusting demodulation of the OFDM waveform;

an FFT engine coupled to the transceiver, the FFT engine producing frequency domain data samples representing information carried by the OFDM waveform;

an FFT engine coupled to the transceiver, the FFT engine producing time domain data samples representing upstream information for transmission by the transceiver on a subset of orthogonal carriers of the OFDM waveform;

a mapper that that receives payload data mapped onto an in-phase (1) and quadrature-phase (Q) constellation based on an output from the FFT engine, wherein the mapper maps said payload data into a at least one baseband payload signal; and

a controller that receives reference data based on at least one of the reference signals, wherein the controller makes adjustments for demodulating the payload data based on the reference data.

22. The remote service unit of claim 21, wherein the subset of orthogonal carriers comprises less than all the OFDM waveform.

23. The remote service unit of claim 21, wherein controller comprises an equalizer that performs an equalization of the payload data based on the reference data.

24. The remote service unit of claim 21, wherein the controller adjusts the payload data based on an error determined from the reference data.

25. The remote service unit of claim 21, wherein the controller adjust a transmission delay and a transmission frequency of upstream transmissions from the receiver to maintain carrier orthogonality within the OFDM waveform.

26. The remote service unit of claim 21, wherein the OFDM waveform is a wireless waveform.

27. A remote service unit for a multiple access OFDM communication system, the remote service unit comprising:

a transceiver for receiving an OFDM waveform, the OFDM waveform having reference signals transmitted over a plurality of reference tones distributed within the OFDM waveform, the references signals for adjusting demodulation of the signals transmitted over the OFDM waveform;

an FFT engine communicatively coupled to the transceiver;

a mapper communicatively coupled to the FFT engine, the mapper using a constellation map to demodulate data from signals transmitted over the OFDM waveform; and

a controller that makes adjustments to the data demodulation based on the receipt of the reference signals;

wherein the transceiver transmits upstream OFDM signals using only a portion of the orthogonal tones within an upstream OFDM waveform based on an allocation of said portion received from a host unit.

28. The remote service unit of claim 27, wherein the reference tones are always reference tones.

29. A remote service unit for a scalable multiple access OFDM communication system, the remote service unit comprising:

a multi-carrier modem for accessing an OFDM waveform having a first bandwidth, wherein the multi-carrier modem provides access to a subset of channels available in a second bandwidth of the OFDM waveform, wherein the second bandwidth is smaller than the first bandwidth;

an n-point FFT engine producing time domain samples of data for modulation onto OFDM carriers within the second bandwidth, the n-point FFT having a number of n-points selected for producing the time domain samples based on a size of the second bandwidth; and

a controller for controlling OFDM carrier spacing of the OFDM carriers modulated by the n-point FFT engine, wherein the controller maintains OFDM carrier spacing of the OFDM carriers modulated by the n-point FFT engine based on a carrier spacing criteria for the first bandwidth.

30. The remote service unit of claim 29, wherein the controller adjusts OFDM carrier spacing of the OFDM carriers modulated by the n-point FFT engine based on instructions from a host unit that receives upstream communications from the remote services unit.

31. The remote service unit of claim 29, wherein the OFDM waveform is a wireless waveform.

32. A remote service unit for a scalable multiple access OFDM communication system, the remote service unit comprising:

a multi-carrier modem for accessing an OFDM waveform having a first bandwidth, wherein the multi-carrier modem provides access to a subset of channels available in a second bandwidth of the OFDM waveform, wherein the second bandwidth is contained within the first bandwidth;

an n-point FFT engine producing time domain samples of data for modulation onto OFDM carriers within the second bandwidth, the n-point FFT having a number of n-points selected for producing the time domain samples based on a size of the second bandwidth; and

a controller for controlling OFDM carrier spacing of the OFDM carriers modulated by the n-point FFT engine, wherein the controller maintains OFDM carrier spacing of the OFDM carriers modulated by the n-point FFT engine based on a carrier spacing criteria for the first bandwidth.

33. The remote service unit of claim 32, wherein the controller adjusts OFDM carrier spacing of the OFDM carriers modulated by the n-point FFT engine based on instructions from a host unit that receives upstream communications from the remote services unit.

34. The remote service unit of claim 32, wherein the OFDM waveform is a wireless waveform.

35. A remote service unit for a multipoint-to-point communication system utilizing a guard band within an OFDM waveform, the remote service unit comprising:

a transceiver communicatively coupled with a host unit in a multipoint-to-point configuration, the transceiver configured to communicate with the host unit via an orthogonal frequency division multiplexing (OFDM) waveform;

a multi-carrier modulator coupled to the transceiver and configured to modulate upstream information onto the orthogonal frequency division multiplexing waveform;

wherein the multi-carrier modulator modulates upstream information onto a plurality of OFDM subcarriers of the OFDM waveform; and

wherein a first OFDM subcarrier of the plurality of distinct OFDM subcarriers is spectrally separated in frequency from a second OFDM subcarrier of the plurality of distinct OFDM subcarriers by a guard band region within the OFDM waveform.

36. The remote service unit of claim 35, wherein the guard band separates an OFDM subcarrier carrying a first type of information from an OFDM subcarrier carrying non-first type information.

37. The remote service unit of claim 35, wherein the multi-carrier modulator comprises at least one symbol mapper for mapping the upstream information into symbols using one or both of QAM symbol mapping and PSK symbol mapping.

38. The remote service unit of claim 37, wherein the multi-carrier modulator further comprises an inverse Fast Fourier Transform (FFT) engine that generating a frame of time domain in-phase and quadrature phase data from the symbol data generated by the symbol mapper.

39. The remote service unit of claim 35, wherein the transceiver further comprises a wireless radio frequency transmitter for transmitting a radio frequency signal comprising the plurality of distinct OFDM subcarriers.

40. The remote service unit of claim 35, wherein the guard band region is sized to include a plurality of unused OFDM subcarriers.

41. A host unit for a multipoint-to-point communication system utilizing a guard band within an OFDM waveform, the host unit comprising:

a transceiver communicatively coupled with a plurality of remote service units in a multipoint-to-point configuration, the transceiver configured to communicate with the plurality of remote service units via an orthogonal frequency division multiplexing (OFDM) waveform;

a multi-carrier modulator coupled to the transceiver and configured to demodulate upstream information from the orthogonal frequency division multiplexing waveform, wherein the OFDM waveform includes OFDM subcarriers spectrally separated in frequency by a region within the OFDM waveform designated as a guard band.

42. The host unit of claim 41, wherein the guard-band separates an OFDM subcarrier carrying a first type of information from an OFDM subcarrier carrying non-first type information.

43. A remote service unit synchronized within a multipoint-to-point communication system, the remote service unit comprising:

a transceiver communicatively coupled with a host unit in a multipoint-to-point configuration, the transceiver configured to communicate with the host unit via an orthogonal frequency division multiplexing (OFDM) waveform;

a multi-carrier modulator coupled to the transceiver and configured to modulate upstream information onto the orthogonal frequency division multiplexing waveform;

wherein the multi-carrier modulator modulates upstream information onto a plurality of distinct OFDM subcarriers of the OFDM waveform;

wherein transmissions on the distinct OFDM subcarriers are synchronized to orthogonally overlap with distinct transmissions from at least one other remote service unit to form the OFDM waveform.

44. A remote service unit synchronized within a multipoint-to-point communication system with at least one other remote service unit such that distinct orthogonal frequency division multiplexing (OFDM) transmissions from the remote service unit and the at least one other remote service unit overlap in time and orthogonally overlap in frequency to combine to form an orthogonal frequency division multiplexing (OFDM) waveform.

45. The remote service unit of claim 44, wherein the remote service unit adjusts timing and frequency of an OFDM signal it transmits such that the OFDM signal overlaps in frequency and time with an OFDM signal from the at least one other remote service unit without interfering with the OFDM signal from the at least one other remote service unit.

46. The remote service unit of claim 44, wherein the remote service unit and the at least one other remote service unit are synchronized within the multipoint-to-point communication system via synchronization with a shared multiple access host unit.

47. A method for quality based assessments of orthogonal channels for remote service units of an OFDM based multiple access system, the method comprising:

monitoring a first subset of orthogonal carriers within an OFDM waveform associated with at least one communication channel, wherein the first subset of orthogonal carriers comprises less than all of the orthogonal carriers within the OFDM waveform;

monitoring a second subset of orthogonal carriers within the OFDM waveform associated with at least one communication channel, wherein the second subset of orthogonal carriers comprises less than all of the orthogonal carriers within the OFDM waveform, wherein the second subset of orthogonal carriers includes different orthogonal carriers that the first subset of orthogonal carriers;

determining a first quality measurement for the first subset of orthogonal carriers;

determining a second quality measurement for the second subset of orthogonal earners;

communicating a notification message regarding the quality measurements for the first subset of orthogonal carriers and the second subset of orthogonal carriers; and

adjusting a frequency of upstream carriers of the OFDM waveform to maintain orthogonality within the OFDM waveform.

48. The method of claim 47, further comprising:

maintaining quality statistics for the first subset of orthogonal carriers in a memory.

49. The method of claim 48, wherein the quality statistics include either a bit error rate or a signal-to-noise ratio.

50. The method of claim 47, further wherein the first subset of orthogonal carriers comprises more than one orthogonal carrier.

51. The method of claim 47, wherein the quality information includes a quality statistic.

52. The method of claim 47, further comprising:

communicating data over the at least one communication channel based on whether the quality measurement for the first subset of orthogonal carriers satisfies a quality standard.

53. The method of claim 47, wherein the first subset of orthogonal carriers are contiguous sets of orthogonal carriers within the OFDM waveform.

54. The method of claim 47, further comprising:

comparing the quality measurement for the second subset of orthogonal carriers against predetermined quality standards.

55. The method of claim 47, further comprising:

determining when the quality measurements for the first subset of orthogonal carriers exceeds allowable limits.