摘要:
A device for communicating digital data over power lines includes a power line interface for transmitting data over at least one band of frequencies. An orthogonal frequency division multiplexing (OFDM) modulation unit generates OFDM symbols using a set of tones for the frequency band. A preamble generation unit generates preamble sequences for the frequency band by using the set of tones used by the OFDM modulation unit. The tones used by the preamble generation unit have a constant magnitude, and a set of phases obtained by quantizing to a small alphabet the phase of a set of tones obtained by taking an IFFT of a portion of a preamble used by a non-interoperable powerline access device. The device may transmit on two or more bands using a sampling frequency clock, wherein a lower band clock frequency is equal to or an integer divisor of a higher band clock frequency.
摘要:
Systems and methods for designing, using, and/or implementing communications in beacon-enabled networks are described. In various implementations, these systems and methods may be applicable to power line communications (PLC). For example, a method may include identifying one of a plurality of orthogonal superframes. The identified superframe may include beacon slots and contention access period (CAP) slots. The beacon slots may follow a sequence of two or more frequency subbands, and the CAP slots may follow the same sequence of two or more frequency subbands. Also, the sequence of two or more frequency subbands may be distinct from other sequences of two or more frequency subbands followed by other beacon slots and CAP slots within others of the plurality of available superframes. The method may then include communicating with another device using the identified superframe.
摘要:
Systems and methods are disclosed for communicating on a pilot wire between Electric Vehicle Service Equipment (EVSE) and an Electric Vehicle (EV). The EVSE and EV exchange a Pulse Width Modulation (PWM) signal on the pilot wire to control charging operations of the EV. Data communications may also be transmitted on the pilot wire, such as between transmit and receive modems. The modems transmit communication signals either continuously, without regard to the state of the PWM signal, or only when the PWM is in an off-state. If transmitting while PWM is on, the modem needs a large coupling impedance and/or a large signal injection. To transmit only when the PWM is off, the modem may use a blocking diode in the coupling circuit or may synchronize to the pulses in the PWM signal.
摘要:
Interference rejection (85) can be applied to a wireless communication signal with reduced computational complexity by producing from a sample vector (y) a plurality of vectors (w) that are smaller than the sample vector. The interference rejection operation can then be applied to each of the smaller vectors individually to decide communication symbols represented by the sample vector.
摘要:
Embodiments of the invention provide method and apparatus for generating a structure in an orthogonal frequency division multiplexing OFDM communication system having a transmitter with one or more transmitting antennas. The method includes composing a frame with a time domain and a frequency domain. The frame has a transmission time interval in the time domain and occupies a bandwidth in the frequency domain. The transmission time interval has multiple orthogonal frequency division multiplexing symbols. A pilot signal is located from a transmitting antenna into two non-consecutive orthogonal frequency division multiplexing symbols of the frame.
摘要:
A wireless communication system (10). The system comprises a user station (12). The user station comprises despreading circuitry (22) for receiving and despreading a plurality of slots received from at least a first transmit antenna (A121) and a second transmit antenna (A122) at a transmitting station (14). Each of the plurality of slots comprises a first channel (DPCH) comprising a first set of pilot symbols and a second channel (PCCPCH) comprising a second set of pilot symbols. The user station further comprises circuitry (50) for measuring a first channel measurement (α1,n) for each given slot in the plurality of slots from the first transmit antenna and in response to the first set of pilot symbols in the given slot. The user station further comprises circuitry (50) for measuring a second channel measurement (a2,n) for each given slot in the plurality of slots from the second transmit antenna and in response to the first set of pilot symbols in the given slot. The user station further comprises circuitry (52) for measuring a phase difference value (φ2(n)) for each given slot in the plurality of slots in response to the first channel measurement and the second channel measurement for the given slot and in response to a ninety degree rotation of the given slot relative to a slot which was received by the despreading circuitry immediately preceding the given slot.
摘要:
Closed loop multiple-antenna wireless communications system with antenna weights determined by maximizing a composite channel signal-to-interference-plus-noise ratio minimum. Multiplexed symbol streams over subsets of antennas enhance throughput.
摘要:
A method for providing closed-loop transmit precoding between a transmitter and a receiver, includes defining a codebook that includes a set of unitary rotation matrices. The receiver determines which preceding rotation matrix from the codebook should be used for each sub-carrier that has been received. The receiver sends an index to the transmitter, where the transmitter reconstructs the precoding rotation matrix using the index, and precodes the symbols to be transmitted using the preceding rotation matrix. An apparatus that employs this closed-loop technique is also described.
摘要:
In a wireless MIMO system, a multimode detector selects detection mode by channel estimation: ill-conditioned channels trigger use of high performance detection, whereas well-behaved channels lead to low complexity detection. Detection modes typically include maximum likelihood, minimum mean squared error, zero forcing, and so forth.
摘要:
A transmitter 200 is provided. The transmitter 200 comprises a mapper 207 operable to map a bit stream into a plurality of tones to promote high data rate multi-band orthogonal frequency division multiplex communication, wherein the tones can take on sixteen or more different values 300. In another embodiment a communications system 1360 is provided that includes a transceiver 1362 that has two or more antennas 1394 and 1396. The transceiver 1362 transmits a first multi-band orthogonal frequency division multiplex signal in multiple input/multiple output mode and receives a second multi-band orthogonal frequency division multiplex signal in multiple input/multiple output mode. In another embodiment, a transceiver 200, 202 transmits a first multi-band orthogonal frequency division multiplex symbol concurrently on a plurality of sub-bands and receives a second multi-band orthogonal frequency division multiplex symbol concurrently on a plurality of sub-bands.