Methods and systems for selecting modulation in an orthogonal frequency division multiplexing system

• US 7,706,349 B2
• Filed: 11/17/2008
• Issued: 04/27/2010
• Est. Priority Date: 02/06/1995
• Status: Expired due to Fees

• Current Assignee: HTC Corporation
• Original Assignee: ADC Telecommunications Incorporated (TE Connectivity Limited)
• Inventors: Geile, Michael J., Roberts, Harold A.
• Primary Examiner(s): Harper, Kevin C
• Application Number:
  US12/272,546
• Publication Number:
  US 20090092040A1
• Time in Patent Office: 526 Days
• Field of Search: 370/252, 370/343, 370/465, 370/480
• US Class Current: 370/343
• 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

Methods and systems for selecting modulation in an orthogonal frequency division multiplexing system are provided. In one embodiment, a method for a remote unit of an OFDM multipoint-to-point communications system comprises: establishing communication between a first remote unit and a host unit, the first remote unit and a plurality of remote units communicatively coupled to the host unit in a multipoint-to-point configuration; transmitting a plurality of tones from the first remote unit such that tones from the first remote unit and at least one other remote unit are simultaneously received at the host unit, the plurality of tones modulated with upstream information using OFDM; modulating up to a plurality of tones using a first modulation scheme when transmitting a first type of upstream information; and modulating up to a plurality of tones using a second modulation scheme when transmitting a second type of upstream information.

Claims

1. A method for a remote unit of an orthogonal frequency division multiplexing (OFDM) multipoint-to-point communications system, the method comprising:

establishing communication between a first remote unit of a plurality of remote units and a host unit, the first remote unit and the plurality of remote units communicatively coupled to the host unit in a multipoint-to-point configuration such that OFDM waveform from distinct remote units of the plurality of remote units combine to a unified OFDM waveform at the host unit;

transmitting a plurality of tones from the first remote unit such that tones from the first remote unit and at least one other remote unit of the plurality of remote units are simultaneously received at the host unit, the plurality of tones modulated with upstream information using orthogonal frequency division multiplexing;

modulating up to a plurality of tones using a first modulation scheme when transmitting a first type of upstream information; and

modulating up to a plurality of tones using a second modulation scheme when transmitting a second type of upstream information.

2. The method of claim 1, further comprising:

adjusting at least one characteristic of at least one tone of the plurality of tones at at least one remote unit such that the orthogonality of the simultaneously received tones is improved as received at the host unit.

3. The method of claim 2, wherein adjusting at least one characteristic comprises adjusting a carrier frequency and a timing.

4. A method for an orthogonal frequency division multiplexing (OFDM) multipoint-to-point communications system, the method comprising:

establishing communication between a plurality of remote units and a host unit, the plurality of remote units communicatively coupled to the host unit in a multipoint-to-point configuration;

receiving an orthogonal frequency division multiplexing waveform at the host unit, the orthogonal frequency division multiplexing waveform comprising a plurality of tones transmitted by more than one of the plurality of remote units that combine to a unified OFDM waveform at the host unit;

wherein receiving an orthogonal frequency division multiplexing waveform includes receiving a first type of upstream information modulated onto up to a plurality of tones using a first modulation scheme; and

wherein receiving an orthogonal frequency division multiplexing waveform includes receiving a second type of upstream information modulated onto up to a plurality of tones using a second modulation scheme.

5. The method of claim 4, further comprising:

adjusting at least one characteristic of at least one tone of the plurality of tones at at least one remote unit, such that the orthogonality of the waveform is improved as received at the host unit.

6. The method of claim 5, wherein adjusting at least one characteristic comprises adjusting a carrier frequency and a timing.

7. A bi-directional communication system, the system comprising:

a multipoint-to-point host unit; and

a plurality of remote units communicatively coupled to the multipoint-to-point host unit through an orthogonal frequency division multiplexing (OFDM) waveform;

wherein the multipoint-to-point host unit receives the orthogonal frequency division multiplexing waveform, the orthogonal frequency division multiplexing waveform comprising a plurality of tones transmitted by more than one of the remote units of the plurality of remote units that combine to a unified OFDM waveform at the host unit;

wherein the plurality of remote units modulate up to a plurality of tones using a first modulation scheme when transmitting a first type of upstream information, and modulate the up to a plurality of tones using a second modulation scheme when transmitting a second type of upstream information.

8. The system of claim 7, wherein the plurality of remote units modulate a plurality of tones with upstream information and adjust at least one characteristic of the plurality of tones such that the orthogonality of the waveform is improved when received at the host unit.

9. The system of claim 8, wherein the plurality of remote units adjust carrier frequency and timing.

10. A method for an orthogonal frequency division multiplexing multipoint-to-point communications system, the method comprising:

establishing communication between a first remote unit of a plurality of remote units and a host unit, the plurality of remote units communicatively coupled to the host unit in a multipoint-to-point configuration;

transmitting non-control data on up to a plurality of tones from the first remote unit using an orthogonal frequency division multiplexing waveform, the up to a plurality of tones modulated with the non-control data using a first modulation scheme; and

transmitting control signals on up to a plurality of tones from the first remote unit using an orthogonal frequency division multiplexing waveform, the up to a plurality of tones modulated with the control signals using a second, more robust modulation scheme;

wherein upstream orthogonal frequency division multiplexing signals from at least two of the plurality of remote units combine to a unified orthogonal frequency division multiplexing waveform at the host unit.

11. The method of claim 10, further comprising:

adjusting at least one characteristic of the plurality of tones such that when any tones are transmitted from the first remote unit and at least one other remote unit of the plurality of remote units, the orthogonality of the tones when received at the host unit is improved.

12. The method of claim 11, wherein adjusting at least one characteristic of the plurality of tones comprises adjusting at least one of a carrier frequency, a carrier amplitude, and a timing.

13. The method of claim 10, wherein transmitting the non-control data comprises transmitting non-control data on tones modulated using one or more of quadrature phase shift keying (QPSK) and quadrature amplitude modulation (QAM).

14. The method of claim 10, wherein transmitting the control signals comprises transmitting control signals on tones modulated using binary phase shift keying (BPSK).

15. A method for an orthogonal frequency division multiplexing multipoint-to-point communications system, the method comprising:

receiving a unified orthogonal frequency division multiplexing waveform at a multipoint-to-point host unit, the unified orthogonal frequency division multiplexing waveform comprising a plurality of tones transmitted by a plurality of remote units, wherein upstream orthogonal frequency division multiplexing signals from at least two of the plurality of remote units combine to form the unified orthogonal frequency division multiplexing waveform at the host unit;

communicating between a first remote unit of the plurality of remote units and the multipoint-to-point host unit, the plurality of remote units communicatively coupled to the multipoint-to-point host unit in a multipoint-to-point configuration;

receiving non-control data in the unified orthogonal frequency division multiplexing waveform, the non-control data modulated using a first modulation scheme; and

receiving control signals in the unified orthogonal frequency division multiplexing waveform, the control signals modulated using a second modulation scheme.

16. The method of claim 15, further comprising:

adjusting one or more of the plurality of tones such that when waveforms are transmitted from the first remote unit and at least one other remote unit of the plurality of remote units, the orthogonality of the unified orthogonal frequency division multiplexing waveform when received at the host unit is improved.

17. The method of claim 15, wherein receiving control signals in the unified orthogonal frequency division multiplexing waveform further comprises receiving the control signals on at least one tone modulated using a second modulation scheme, the second modulation scheme more robust than the first modulation scheme.

18. The method of claim 15, wherein receiving the non-control data in the unified orthogonal frequency division multiplexing waveform further comprises receiving the non-control data on at least one tone modulated using at least one of quadrature phase shift keying (QPSK) and quadrature amplitude modulation (QAM).

19. The method of claim 15, wherein receiving control signals in the unified orthogonal frequency division multiplexing waveform further comprises receiving the control signals on at least one tone modulated using binary phase shift keying (BPSK).

20. A method for an orthogonal frequency division multiplexing multipoint-to-point communications system, the method comprising:

receiving a unified orthogonal frequency division multiplexing waveform at a multipoint-to-point host unit, the unified orthogonal frequency division multiplexing waveform comprising a plurality of tones transmitted by a plurality of remote units, wherein upstream orthogonal frequency division multiplexing signals from at least two of the plurality of remote units combine to form the unified orthogonal frequency division multiplexing waveform at the host unit; and

modulating one or more of the plurality of tones with non-control data using a first modulation scheme; and

modulating one or more of the plurality of tones with control signals using a second modulation scheme, the second modulation scheme more robust than the first modulation scheme.

21. The method of claim 20, wherein receiving the non-control data in the unified orthogonal frequency division multiplexing waveform further comprises receiving the non-control data on at least one tone modulated using at least one of quadrature phase shift keying (QPSK) and quadrature amplitude modulation (QAM).

22. The method of claim 20, receiving control signals in the unified orthogonal frequency division multiplexing waveform further comprises receiving the control signals on at least one tone modulated using binary phase shift keying (BPSK).