최소 단어 이상 선택하여야 합니다.
최대 10 단어까지만 선택 가능합니다.
다음과 같은 기능을 한번의 로그인으로 사용 할 수 있습니다.
NTIS 바로가기다음과 같은 기능을 한번의 로그인으로 사용 할 수 있습니다.
DataON 바로가기다음과 같은 기능을 한번의 로그인으로 사용 할 수 있습니다.
Edison 바로가기다음과 같은 기능을 한번의 로그인으로 사용 할 수 있습니다.
Kafe 바로가기국가/구분 | United States(US) Patent 등록 |
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국제특허분류(IPC7판) |
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출원번호 | US-0927498 (2007-10-29) |
등록번호 | US-8199632 (2012-06-12) |
발명자 / 주소 |
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출원인 / 주소 |
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대리인 / 주소 |
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인용정보 | 피인용 횟수 : 1 인용 특허 : 550 |
Systems and methods for orthogonal frequency division multiplexing are provided. In one embodiment, a multi-carrier modem comprises: a receiver configured to receive a waveform comprising a plurality of spectrally overlapping carrier signals from at least two of a plurality of remote units, wherein
Systems and methods for orthogonal frequency division multiplexing are provided. In one embodiment, a multi-carrier modem comprises: a receiver configured to receive a waveform comprising a plurality of spectrally overlapping carrier signals from at least two of a plurality of remote units, wherein the plurality of spectrally overlapping carrier signals are modulated using an inverse Fourier transform algorithm; a transmitter; a processor coupled to the transmitter, wherein the processor outputs data for transmission to the transmitter, wherein the processor applies an inverse Fourier transform algorithm to the data provided to the transmitter; and a controller programmed to analyze a training signal received from a first remote unit and adjust receiver equalizer parameters based on the training signal.
1. A multi-carrier modem, the modem comprising: a receiver configured to de-modulate symbols from at least one of a plurality of spectrally overlapping carrier signals;a transmitter configured to modulate symbols onto at least one of a plurality of the spectrally overlapping carrier signals;a proces
1. A multi-carrier modem, the modem comprising: a receiver configured to de-modulate symbols from at least one of a plurality of spectrally overlapping carrier signals;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;a controller programmed to instruct the transmitter to transmit a training pattern to a host unit, the training pattern having a pre-defined structure known to the host. 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 the 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 multi-carrier modem, the modem comprising: a receiver configured to receive a waveform comprising a plurality of spectrally overlapping carrier signals from at least two of a plurality of remote units, wherein the plurality of spectrally overlapping carrier signals are modulated using an inverse Fourier transform algorithm;a transmitter;a processor coupled to the transmitter, wherein the processor outputs data for transmission to the transmitter, wherein the processor applies an inverse Fourier transform algorithm to the data provided to the transmitter; anda controller programmed to analyze a training signal received from a first remote unit and adjust receiver equalizer parameters based on the training signal. 5. The multi-carrier modem of claim 4, wherein the inverse Fourier transform algorithm is based on one of an inverse Fast Fourier Transform (FFT) algorithm and an inverse Discrete Fourier Transform (DFT) algorithm. 6. 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; andwherein 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. 7. The remote service unit of claim 6, wherein the guard band separates an OFDM subcarrier carrying a first type of information from an OFDM subcarrier carrying non-first type information. 8. The remote service unit of claim 6, wherein the multicarrier 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. 9. The remote service unit of claim 8, wherein the multicarrier 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. 10. The remote service unit of claim 6, wherein the transceiver further comprises a wireless radio frequency transmitter for transmitting a radio frequency signal comprising the plurality of distinct OFDM subcarriers. 11. The remote service unit of claim 6, wherein the guard band region is sized to include a plurality of unused OFDM subcarriers. 12. 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. 13. The host unit of claim 12, wherein the guard-band separates an OFDM subcarrier carrying a first type of information from an OFDM subcarrier carrying non-first type information. 14. 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. 15. A remote service unit comprising: a transceiver configured to communicate using an orthogonal frequency division multiplexing (OFDM) waveform whereby,the remote service unit is 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. 16. The remote service unit of claim 15, 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. 17. The remote service unit of claim 15, 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. 18. A remote service unit using minimum allocations in 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 a composite orthogonal frequency division multiplexing (OFDM) waveform of adjacent spectrally overlapping sub-carriers;a multi-carrier modem coupled to the transceiver and configured to modulate upstream payload data onto a plurality OFDM sub-carriers transmitted by the transceiver, the multi-carrier modem synchronized with the host unit such that the upstream payload data transmitted by the transceiver, and other upstream OFDM signals from other transceivers received at the host unit, combine to form the composite OFDM waveform;wherein the remote unit receives channel allocations from the host unit, wherein channel allocations for transport of upstream payload data always provide at least a minimum allocation of at least two OFDM sub-carriers. 19. The remote service unit of claim 18, wherein the at least two OFDM sub-carriers comprise contiguous orthogonal tones within the composite OFDM waveform. 20. The remote service unit of claim 18, wherein the at least two OFDM sub-carriers is an allocation of exactly two tones. 21. The remote service unit of claim 18, wherein the upstream payload data includes at least one of telephony data, digital video data, voice data, or financial transaction data. 22. A remote communication device using minimum allocations in a multipoint-to-point communication system, the device comprising: at least one symbol mapper that maps data into symbols using quadrature amplitude modulation (QAM) symbol mapping and phase-shift keying (PSK) symbol mapping;a Fast Fourier Transform (FFT) engine that receives a frame of parallel data based on symbol data generated by the symbol mapper, the Fast Fourier Transform (FFT) engine generating a frame of time domain in-phase and quadrature phase data from the symbol data generated by the symbol mapper;at least one converter generating an analog signal based on the stream of time domain in-phase and quadrature phase data;a radio frequency transmitter for transmitting a radio frequency signal based on the analog signal;wherein the radio frequency signal comprises a plurality of orthogonal frequency division multiplexing (OFDM) sub-carriers transmitted by the transmitter, the plurality of OFDM sub-carriers synchronized in time and frequency to combine with OFDM subcarriers transmitted by at least one other transmitter to form a composite OFDM waveform at a host unit;wherein the minimum bandwidth allocation received by the remote communication device from the host unit for upstream payload comprises at least two OFDM sub-carriers within the composite OFDM waveform available for transmitting the radio frequency signal. 23. The remote service unit of claim 22, wherein the minimum bandwidth allocation of at least two OFDM sub-carriers comprises contiguous orthogonal tones within the composite OFDM waveform. 24. The remote service unit of claim 22, wherein the minimum bandwidth allocation of at least two OFDM sub-carriers is an allocation of exactly two tones. 25. The remote service unit of claim 22, wherein the upstream payload data includes at least one of telephony data, digital video data, voice data, or financial transaction data.
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