摘要:
The invention comprises using beamforming antenna to coherently transmit an information signal to a receiver using two or more directional beams. In one embodiment, the phase and timing of the information signals carried by each directional beams are adjusted such that the signals arrive synchronously at the mobile terminal. Time synchronization may be obtained by delaying signals transmitted on selected directional beams to compensate for different propagation delays, or by preconditioning and filtering the signals using a channel coefficient matrix.
摘要:
A mobile communication system comprises a plurality of cells, with each cell including a network of microstations distributed more or less uniformly throughout the cell. A central controller connected to the network of microstations selects a group of microstations in the vicinity of the mobile terminal to transmit information to the mobile terminal. The selected microstations in the active set for a given mobile terminal is continuously updated as the mobile terminal moves through the network of microstations to form a virtual cell that follows the mobile terminal through the network. Transmission conflicts between two mobile terminals is avoided by inhibiting transmissions from an active microstation to at least one of the co-channel mobile terminals when a transmission conflict is detected.
摘要:
A transmitter is provided for simultaneously transmitting a plurality of signals in a plurality of directive beams to corresponding destination stations, each destination station located in a separate fan within a service area. The transmitter includes a plurality of beamformers, each beamformer receiving one of the signals to be transmitted to an associated fan, each of the beamformers having a plurality of outputs for each different signal to be transmitted. A plurality of Butler matrices each receive one of the plurality of outputs from the plurality of beamformers for each different signal to be transmitted, each Butler matrix having a plurality of outputs in phased relationship to one another, wherein each of the signals to be transmitted is simultaneously provided across the outputs of each Butler matrix in a phased relationship. An antenna is provided with an aperture within which a two-dimensional array of antenna elements are disposed, wherein equal fractions of adjacent antenna elements are connected to the outputs of each Butler matrix, and wherein each of the plurality of signals are simultaneously transmitted by the entire two-dimensional array of antenna elements. Each of the plurality of beamformers receives steering control signals for steering the direction of each beam within its respective fan.
摘要:
An adjustable matching network is provided for a wireless communications device transmitting and receiving signals in multiple frequency bands via an antenna. The adjustable matching network selectively connecting the antenna to a select power amplifier corresponding to a selected transmit frequency band and automatically matching the impedance of the antenna to the select power amplifier. The adjustable matching network also selectively connecting the antenna to a select bandpass filter corresponding to a selected receive frequency band and automatically matching the impedance of the antenna to the select bandpass filter.
摘要:
Methods and systems are provided for communicating encoded data. L received encoded signal values including soft information are received and transformed to L data symbols. In various embodiments, the L received encoded signal values are demodulated and the demodulated L received encoded signal values are convolutional decoded using a rate one convolutional decoder having only one output symbol per input symbol to provide the L data symbols, wherein the L received encoded signal values are convolutional encoded using a rate one convolutional encoder having only one output symbol per input symbol. In other embodiments of the present invention the L received encoded signal values are transformed using associated spectral energy at a plurality of frequency ranges within a bandwidth of a channel over which the L received encoded signal values are received for at least one of the L received encoded signal values.
摘要:
A method and apparatus is described for transforming a key variable used for scrambling mobile data traffic between a terminal and a network in alternate ways based on a value transmitted to the terminal from the network. Transformation is accomplished by passing portions of the key variable through a series of S-boxes, which provide a mapping between inputs and outputs. The method and apparatus is explained also in the context of a satellite communications system, in which a terminal can be located in a different continent/country from the terminal's home location. Enciphered communication is enabled between the foreign satellite gateway and the roaming terminal after the foreign gateway communicates with the terminal's native gateway. The native gateway transmits one or more cipher variables in the communication. Moreover, the value determining which way to cipher the data traffic can be based on numerous factors, including aspects of the satellite communication system.
摘要:
Methods and systems for time synchronizing a receiver to a spread spectrum signal are described. Exemplary embodiments of the present invention provide for at least a two step process in which, at a first step, a number of candidate synchronization frequencies or timings are identified, followed by confirming one of the candidates as a correct synchronization state at a second or final step. According to the present invention, the confirmation step may be performed at the same time as the step of identifying further candidates by processing the same received signal samples in different ways.
摘要:
A method and system for the transmission, reception, and processing of 4-level and 8-level signaling symbols is provided. An inventive modulator is provided for modulating 4-level signaling symbols using an 8-level modulator. Further, this inventive modulator is able to produce 4-level modulation when modulating 4-level signaling symbols using an 8-level modulator, where the 4-level modulation represents the 4-level symbol sequence modulated. Further, a constrained/unconstrained demodulator is provided which is able to demodulate both 4-level signaling symbols and 8-level signaling symbols. The inventive demodulator accomplishes this by limiting the number of new symbol hypotheses and path histories to 4 when working with 4-level signaling symbols, and setting the number of new symbol hypotheses and path histories to 8 when working with 8-level signaling symbols. Additionally, an error correction decoder is provided which is also able to decode a demodulated signal which contains both 4-level and 8-level signaling symbols. The inventive error correction decoder accomplishes this by utilizing an interleaver that only places bits in the 2-bit positions of the 3-PSK soft values that correspond to the 2-bits of QPSK to decode 4-level signalling symbols, and utilizing an interleaver that places bits in all three of the possible bit positions of a symbol to decode 8-level signalling symbols.
摘要:
Communication systems and methods are provided allowing a single mode mobile terminal to support mobile assisted signal strength measurement operations in both a fixed frequency reuse based communication network and an adaptive channel allocation based communication network. Candidate base station signal strength measurements are requested by a fixed frequency reuse type network, measured by the mobile terminal and provided to the fixed frequency reuse type network which is seeking to identify a strongest signal for mobile assisted handover operations. In addition, interference signal strength measurements are requested by an adaptive channel allocation type network, measured by the mobile terminal and provided to the adaptive channel allocation type network by the mobile terminal. No redundant circuitry is required in the mobile terminal. Instead, the mobile terminal executes the same operations using the same hardware regardless of whether the requested measurement is of a candidate signal strength or an interference signal.
摘要:
An apparatus and method decode information signals which have been encoded using a tailbiting error-correction codeword. The method generally includes the steps of initializing a number of decoder states corresponding to all possible starting states of the encoder to have equal associated likelihood metrics. The metrics are updated to reflect a likelihood metric for each of the decoder states given the received information signals. Further information signals, representative of further coded symbols, are received and a decoder state having the highest associated likelihood metric is extended by updating the likelihood metric to produce new likelihood metrics for each possible hypothesized extended decoded information symbol, given the further received information signals. An assumed value for the extended decoder information symbol is appended to the symbol history for the extended decoder state. The method continues to receive further information signals and to extend the decoder state having the highest likelihood metric by hypothesizing additional information symbols to produce extended decoder states until a last information symbol coded in the tailbiting codeword has been hypothesized. Final metrics are computed for each of the corresponding extended decoder states and if one of the final metrics is indicative of the highest likelihood metric, then the symbol history of the associated decoder state is used as the decoded information.