摘要:
A modulator capable of providing a fractional sample or symbol 995486 time employs a decimation counter (23) responsive to a clock having a frequency equal to M/N.times.(data symbol clock), where M is an interpolation factor and N is a decimation factor, for generating a data symbol clock to select FSK symbols from a sampled data array (21). A multiplier (26) receives the FSK symbols and multiplies the symbols by a weighting factor determined by the decimation counter. When the decimation counter wraps around due to a modulo M operation, a fractional weight is calculated for the current FSK symbol, then a new FSK symbol is selected, and then a fractional weight is calculated for the new FSK symbol. When the decimation counter has not wrapped, the full weighting, N, is output for the current FSK symbol.
摘要:
A spatial diversity system for digital mobile telephone networks which comprises at least two antennas, one antenna being part of a primary (or master) unit and the other being part of a diversity (or slave) unit, each unit having processing means to detect the "quality" of digital audio signals received by their respective antennas, the "quality" comprising link quality, AGC level and parity errors; the primary unit being capable of comparing the "quality" of the audio signals received by each antenna, selecting the higher "quality" signal and transmitting the higher "quality" signal to the telephone network.
摘要:
A decoder decodes a plurality of received convolutionally encoded date signals simultaneously. At least two of the encoded data signals have a different data rate. The decoder receives undecoded I and Q symbols from the plurality of encoded data signals and outputs Euclidian distances corresponding to each encoded signal. Each data signal's distances are mapped on to a trellis. To output decoded symbols of each data signal, decisions are traced back in each data signal's trellis.
摘要:
A Supervisory Audio Tone (SAT) based Carrier-to-Interference (C/I) ratio measurement system uses the SAT tone to determine the desired signal to undesired interferers so that an intelligent hand-off decision can be made in a digital cellular communication system. The measurement is implemented by digital signal processors which allows additional signal processing and subsequently noise rejection over analog techniques. The received level of the desired SAT as well as the received levels of the SATs for the co-channel interferers is detected. The ratio of the desired SAT level to the sum of the undesired SAT levels provides the C/I measurement. By monitoring this C/I measurement, the base station can determine when to make a hand-off. This SAT based C/I measurement system also aids in the selection of a candidate cell to which the subscriber is handed-off. Surveillance receivers in the candidate cells make SAT based C/I measurements as well as Received Signal Strength Indication (RSSI) measurements. The cell with the most favorable channel conditions would be the cell to which the hand-off is made.
摘要:
A wireless digital telephone system containing at least one emulated base station plus one or more subscriber stations, the emulated base station comprising a station similar to the subscriber station but having the capability of initiating a synchronization process whereby it is enabled to assign time slots to the subscriber station within the frame pattern of an amplitude signal by means of monitoring for positive edges in the signal.
摘要:
A wireless digital telephone system containing at least one emulated base station plus one or more subscriber stations, the emulated base station comprising a station similar to the subscriber station but having the capability of initiating a synchronization process whereby it is enabled to assign time slots to the subscriber station within the frame pattern of an amplitude signal by means of monitoring for positive edges in the signal.
摘要:
A modem interface transfers data between a high data rate interface and a wireless interface. The modem interface has a plurality of parallel data highways. Each data highway has frames with time slots for transferring data. The plurality of highways outputs data to the high data rate interface and the wireless interface in selected time slots. At least one of the data highways has an input configured to receive data from the high data rate interface in selected time slots. At least one of the data highways has an input configured to receive data from the wireless interface in selected time slots. A processor controls the transfer of data between the plurality of highways.
摘要:
A method for simultaneously receiving and processing multiple channels of data at independent rates which share a same frequency spectrum begins with receiving a multichannel data communication signal having multiple data channels at independent data rates on the same frequency spectrum. Next, selected channels of data of the received signal are separated and the data rate for each channel is identified. Then each separated channel of the received signal is decoded at an assigned data rate using a common decoding memory. Lastly, each separated channel is directed to a different decoding means and each decoding means is assigned a data rate responsive to the identification of data rates when the channels were separated.
摘要:
A spread spectrum base station receives a multichannel data communication signal. The multichannel data communication signal has multiple data channels at independent data rates on a same frequency spectrum. Selected channels of data of the received signal are separated and the data rate for each channel identified. Each separated channel is decoded at an assigned data rate. A common decoding memory is shared.
摘要:
A spread spectrum mobile station receives a multichannel data communication signal. The multichannel data communication signal has multiple data channels at independent data rates on a same frequency spectrum. Selected channels of data of the received signal are separated and the data rate for each channel identified. Each separated channel is decoded at an assigned data rate. A common decoding memory is shared.