Abstract:
A multi-channel communication system is disclosed in which a base station is in communication with a plurality of user terminals. To enable the user terminals to perform equalisation on signals sent to the base station, the base station transmits periodic multi-carrier reference bursts on a channel assigned to the user terminals for use in transmission of signals to the base station. The user terminal can analyse the reference signals that it receives from the base station and from that analysis deduce the condition of the channel and adjust the signals that it transmits accordingly. The system may be embodied in a multiple access orthogonal frequency division multiplexing arrangement, for example, being in accordance with an ETSI EN300xxx standard, in which data is digitally encoded in RF signals. It may also be embodied in Voice over IP communication.
Abstract:
A method for generating a beamforming training (BFT) unit includes generating a physical layer (PIlY) preamble of the BFT unit and generating a first encoding block and a second encoding block using PHY data and MAC data, including at least one of i) using a number of padding bits in a PHY layer of the BFT unit such that the BFT unit consists of the PHY preamble, the first encoding block, and the second encoding block, and ii) generating a MAC protocol data unit (MPDU) having a length such that the BFT unit consists of the PHY preamble, the first encoding block, and the second encoding block.
Abstract:
A method and system for determining a step size of an adaptive equalizer for a digital data receiver. The data received by the receiver includes coded symbols and uncoded symbols. The method includes determining a first error estimate based on decoded symbols corresponding to the coded symbols, determining a second error estimate based on the uncoded symbols, adaptively selecting the first error estimate or the second error estimate based on a convergence criterion, and determining a step size based on the selected error estimate.
Abstract:
A multicarrier receiver generates a quantized transmit beamformer matrix (V) for each subcarrier of a multicarrier communication channel for use by a multicarrier transmitting station. The multicarrier receiver applies a corrected receiver beamformer matrix (U H ) to received subcarriers signals generated by signals received from the transmitting station.
Abstract translation:多载波接收机为由多载波发射台使用的多载波通信信道的每个子载波生成量化的发射波束形成矩阵(V)。 多载波接收机对由从发射站接收的信号产生的接收到的子载波信号应用经校正的接收机波束形成矩阵(U H SUP)。
Abstract:
Performing channel estimation with a limited receiver includes performing a first estimation of a first portion of a signal to obtain first parameters of the portion of the signal. The first portion of the signal has predetermined offsets added during transmission. The predetermined offsets are based on the modulation format of a second portion. The first and second portions have different modulation formats. The first portion of the signal is demodulated using the first parameters to recover data symbols. An equalizer is tranined using a decision directed technique to obtain equalizer coefficients. The demodulated first portion of the signal is checked to confirm correct demodulation. The second protion of the signal is then demodulated using the equalizer coefficents.
Abstract:
A scheme for indicating the presence of stealing or other information in a digital mobile radio communications system. A sequence of pilot symbols and/or synchronisation symbols that can be distinguished from a normal sequence of pilot symbols and/or synchronisation symbols is included in a transmission to indicate the presence of stealing. A receiver determines whether a received transmission includes the stealing sequence or the normal sequence and decodes the transmission accordingly.
Abstract:
A communication device for transmitting beamformed signals using implicit channel sounding is described. The communication device includes a processor and instructions stored in memory. The communication device receives one or more sounding signals and computes a channel estimate based on the one or more sounding signals. Frequency offset compensation is applied to the channel estimate by the communication device. The communication device also computes a precoding matrix based on the channel estimate and transmits a beamformed signal using the precoding matrix. Another communication device for receiving beamformed signals using explicit channel sounding is also described. The communication device includes a processor and instructions stored in memory. The communication device receives one or more sounding signals, computes a channel estimate based on the one or more sounding signals and applies amplitude compensation to the channel estimate. The communication device also sends estimated channel data and receives a beamformed signal.
Abstract:
A method for digital communication includes generating time-domain symbols (54) having a predetermined symbol duration in accordance with a discrete multi-tone (DMT) modulation scheme. A cyclic extension (56,58) is added to each of the time-domain symbols so as to form data blocks (50,52) having a block length that is not an integer multiple of the symbol duration. A training pattern is generated on one or more tones of the DMT modulation scheme, wherein the training pattern is periodic over a sequence of the data blocks with a period equal to the symbol duration. The sequence of the data blocks is transmitted over a communication channel (26) to a receiver (24), which processes the training pattern so as to determine a response of the channel to the one or more tones.
Abstract:
A system and method for enhancing the performance of an equalizer in a modem (100) that uses stored parameters in a parameter storage memory (933) of a receiver module (102) for each burst from each remote site to demodulate a received data stream. The parameter storage memory (933) contains channel characteristics, in the form of taps, corresponding to each remote site. The parameter storage (933) sends taps values to the digital equalization module (930) corresponding to the remote site that is presently sending us an uplink burst to the modem (100). The acquisition, tracking and modulation control module (918) genertaes an index of remote sites and their associated tap values to expedite their retrieval from the parameter storage memory (933).