Increased capacity communications systems, methods and/or devices

{
  "publication_number": "US2010002789A1",
  "country": "US",
  "kind": "A1",
  "title": "Increased capacity communications systems, methods and/or devices",
  "abstract": "Communications architectures, systems, devices and/or methods are disclosed that can increase capacity of conventional OFDM/OFDMA systems, devices, methods and/or protocols by as much as 100%. Conventional OFDM/OFDMA transmitter/receiver architectures, methods, systems and/or devices are improved upon via additional signal processing to provide the increased capacity and reduce non-linear distortion effects on higher-order modulation alphabets such as, for example, 256-QAM.",
  "claims": [
    "1. A method comprising: receiving a signal comprising N first sub-carriers; wherein N≧2; generating 2N′ samples of the signal; wherein N′≧N; performing a first transformation on a first sub-set of the 2N′ samples; performing a second transformation on a second sub-set of the 2N′ samples; and combining an element of the first transformation with an element of the second transformation.",
    "2. A method according to claim 1, wherein the N first sub-carriers are orthogonal therebetween.",
    "3. A method according to claim 1, wherein the signal further comprises M second sub-carriers; M≧0; wherein the M second sub-carriers are superimposed on the N first sub-carriers over a frequency interval of bandwidth B Hz that is substantially occupied by the N first sub-carriers and over a time interval of T seconds in duration over which the N first sub-carriers are defined.",
    "4. A method according to claim 3, wherein the M second sub-carriers are orthogonal therebetween and wherein at least one of the M second sub-carriers is not orthogonal to at least one of the N first sub-carriers.",
    "5. A method according to claim 1, wherein the 2N′ samples comprise 2N′ time-domain samples.",
    "6. A method according to claim 5, wherein at least one of the 2N′ time-domain samples comprises a complex value.",
    "7. A method according to claim 1, wherein the signal comprises a bandwidth of B Hz, wherein B≧N/T and wherein T denotes a signaling interval over which the N first sub-carriers are defined.",
    "8. A method according to claim 7, wherein receiving a signal comprises receiving a passband signal wherein B is centered at a frequency f 1 and wherein the passband signal is frequency shifted to a frequency f 2 prior to the generating 2N′ samples of the signal.",
    "9. A method according to claim 8, wherein f 2 =B/2, f 2 =0, f 2 <f 1 or f 2 ≧f 1.",
    "10. A method according to claim 3, wherein a spacing between two adjacent sub-carriers of the N first sub-carriers is 1/T Hz, a spacing between two adjacent sub-carriers of the M second sub-carriers is 1/T Hz and a spacing between a first sub-carrier of the N first sub-carriers and a sub-carrier of the M second sub-carriers that is adjacent to the first sub-carrier of the N first sub-carriers is ½T Hz.",
    "11. A method according to claim 3, wherein the first sub-set of the 2N′ samples comprises a first set of N″ samples and the second sub-set of the 2N′ samples comprises a second set of N′″ samples; wherein N″≦2N′ and N′″≦2N′.",
    "12. A method according to claim 11, wherein N″=N′″=N′, a spacing between two adjacent samples of the first set of N″ samples is T/N′ seconds, a spacing between two adjacent samples of the second set of N′″ samples is T/N′ seconds and a spacing between a first sample of the first set of N″ samples and a sample of the second set of N′″ samples that is adjacent to the first sample of the first set of N″ samples is T/2N′ seconds.",
    "13. A method according to claim 1, wherein the first transformation and the second transformation each comprises a time-domain to frequency-domain transformation.",
    "14. A method according to claim 13, wherein the time-domain is a discrete time-domain, the frequency-domain is a discrete frequency-domain and wherein the time-domain to frequency-domain transformation comprises a Discrete Fourier Transform and/or a Fast Fourier Transform.",
    "15. A method according to claim 1, further comprising modifying the element of the first transformation and/or modifying the element of the second transformation prior to the combining.",
    "16. A method according to claim 15, wherein combining comprises: forming γ T b+δ T r; wherein b comprises the element of the first transformation, r comprises the element of the second transformation, γ T b comprises modifying the element of the first transformation, δ T r comprises modifying the element of the second transformation and wherein the superscript T denotes transpose and/or conjugate transpose.",
    "17. A method according to claim 16, further comprising: calculating γ and δ such that the statistical expectation E[|γ T b+δ T r−B k | 2] is minimized; wherein E[•] denotes statistical expectation, |•| denotes magnitude and B k denotes a data element that is associated with a k th sub-carrier; k=1, 2,..., N.",
    "18. A method according to claim 17, wherein calculating comprises calculating for at least one value of k; k=1, 2,..., N.",
    "19. A method according to claim 18, further comprising: using γ T b+δ T r to determine an estimate of B k for at least one value of k.",
    "20. A communications receiver comprising a processor that is configured to: receive a signal comprising N first sub-carriers; wherein N≧2; generate 2N′ samples of the signal; wherein N′≧N; perform a first transformation on a first sub-set of the 2N′ samples; perform a second transformation on a second sub-set of the 2N′ samples; and combine an element of the first transformation with an element of the second transformation.",
    "21. A communications receiver according to claim 20, wherein the N first sub-carriers are orthogonal therebetween.",
    "22. A communications receiver according to claim 20, wherein the signal further comprises M second sub-carriers; M≧0; wherein the M second sub-carriers are superimposed on the N first sub-carriers over a frequency interval of bandwidth B Hz that is substantially occupied by the N first sub-carriers and over a time interval of T seconds in duration over which the N first sub-carriers are defined.",
    "23. A communications receiver according to claim 22, wherein the M second sub-carriers are orthogonal therebetween and wherein at least one of the M second sub-carriers is not orthogonal to at least one of the N first sub-carriers.",
    "24. A communications receiver according to claim 20, wherein the 2N′ samples comprise 2N′ time-domain samples.",
    "25. A communications receiver according to claim 24, wherein at least one of the 2N′ time-domain samples comprises a complex value.",
    "26. A communications receiver according to claim 20, wherein the signal comprises a bandwidth of B Hz, wherein B≧N/T and wherein T denotes a signaling interval over which the N first sub-carriers are defined.",
    "27. A communications receiver according to claim 26, wherein the signal comprises a passband signal, wherein B is centered at a frequency f 1 and wherein the passband signal is frequency shifted to a frequency f 2 before the processor generates the 2N′ samples of the signal.",
    "28. A communications receiver according to claim 27, wherein f 2 =B/2, f 2 =0,f 2 <f 1 or f 2 ≧f 1.",
    "29. A communications receiver according to claim 22, wherein a spacing between two adjacent sub-carriers of the N first sub-carriers is 1/T Hz, a spacing between two adjacent sub-carriers of the M second sub-carriers is 1/T Hz and a spacing between a first sub-carrier of the N first sub-carriers and a sub-carrier of the M second sub-carriers that is adjacent to the first sub-carrier of the N first sub-carriers is ½T Hz.",
    "30. A communications receiver according to claim 22, wherein the first sub-set of the 2N′ samples comprises a first set of N″ samples and the second sub-set of the 2N′ samples comprises a second set of N′″ samples; wherein N″≦2N′ and N′″≦2N′.",
    "31. A communications receiver according to claim 30, wherein N″=N′″=N′, a spacing between two adjacent samples of the first set of N″ samples is T/N′ seconds, a spacing between two adjacent samples of the second set of N′″ samples is T/N′ seconds and a spacing between a first sample of the first set of N″ samples and a sample of the second set of N′″ samples that is adjacent to the first sample of the first set of N″ samples is T/2N′ seconds.",
    "32. A communications receiver according to claim 20, wherein the first transformation and the second transformation each comprises a time-domain to frequency-domain transformation.",
    "33. A communications receiver according to claim 32, wherein the time-domain is a discrete time-domain, the frequency-domain is a discrete frequency-domain and wherein the time-domain to frequency-domain transformation comprises a Discrete Fourier Transform and/or a Fast Fourier Transform.",
    "34. A communications receiver according to claim 20, wherein the processor is further configured to modify the element of the first transformation and/or to modify the element of the second transformation before the processor combines the element of the first transformation with the element of the second transformation.",
    "35. A communications receiver according to claim 34, wherein the processor is further configured to form γ T b+δ T r; wherein b comprises the element of the first transformation, r comprises the element of the second transformation, γ T b comprises the modified element of the first transformation, δ T r comprises the modified element of the second transformation and wherein the superscript T denotes transpose and/or conjugate transpose.",
    "36. A communications receiver according to claim 35, wherein the processor is further configured to calculate the vectors γ and δ such that the statistical expectation E[|γ T b+bδ T r−B k | 2] is minimized; wherein E[•] denotes statistical expectation, |•| denotes magnitude and B k denotes a data element that is associated with a k th sub-carrier; k=1, 2,..., N.",
    "37. A communications receiver according to claim 36, wherein the processor is configured to calculate the vectors γ and δ for at least one value of k; k=1, 2,..., N.",
    "38. A communications receiver according to claim 37, wherein the processor is further configured to use γ T b+δ T r to determine an estimate of B k for at least one value of k."
  ],
  "description_excerpt": "This invention relates to wireless and wireline communications systems, methods and/or devices and more particularly to wireless and wireline communications systems, methods and/or devices that transmit/receive information using an Orthogonal Frequency Division Multiplexed (“OFDM”) and/or Orthogonal Frequency Division Multiple Access (“OFDMA”) protocol.\n\nIn communications systems, wireline and/or wireless, a primary design objective is to reduce or minimize noise and/or interference, while increasing or maximizing desired signal strength, in order to increase or maximize system capacity. Much research has been conducted, and continues to be conducted, towards this objective. It is well known, for example, that a communications receiver that is based upon “matched filter” principles is optimum in terms of maximally rejecting noise while maximally acquiring a desired signal. Further examples relate to the many receiver and/or transmitter “equalization/cancellation” techniques that have been developed to combat effects of non-ideal channels and/or system devices that generate linear and/or non-linear Inter-Symbol Interference (“ISI”), Adjacent Channel Interference (“ACI”) and/or Cross Polarization Interference (“CPI”).\n\nAt the current time, it appears that OFDM/OFDMA-based systems will proliferate as is evident by developments in the standardization and deployment of OFDM/OFDMA-based systems, such as, for example, Wi-Fi, Wi-MAX and LTE.",
  "cpc": [
    "H04L 27/2647"
  ],
  "ipc": [
    "H04L 27/28",
    "H04K 1/10"
  ],
  "assignees": [
    "EICES Res Inc"
  ],
  "inventors": [
    "Peter D. Karabinis"
  ],
  "filing_date": "2009-06-09",
  "publication_date": "2010-01-07",
  "priority_date": "2008-07-07",
  "application_number": "US-48108409-A",
  "family_id": "41464395",
  "cited_by_count": 32,
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}