摘要:
A communication system and method for transmitting relatively short data messages in the communication system. A dedicated frequency is sequentially switched into each of a plurality of satellite beams or traffic channels to transmit data messages at an increased power level to provide an increased signal margin. The increased power level of the dedicated frequency can be combined with coding and bit and message repetition to further increase the signal margin.
摘要:
A synchronization method and apparatus for synchronizing a receiver, such as a radiotelephone operable in a cellular communication system with a transmitter. Synchronization sequences are transmitted as parts of a control signal to the receiver. The synchronization sequences are formed of either a dotting sequence or a set of m-sequences. Such synchronization sequences are of high margins and also permit synchronization of the user terminal responsive to a reduced number of calculations.
摘要:
A cellular communications satellite system is disclosed which comprises a plurality of ground-based base stations, mobile stations, and at least one orbiting satellite for relaying signals between the base stations and mobile stations. A Plurality of feederlinks are used between the base stations and the satellite for transmitting signals and power from the ground stations to the satellite.
摘要:
A method and system for transmitting short data messages in a control station-based TDMA radiocommunication system. Selected TDMA frames are assigned as message frames, and one or more data slots from each message frame are assigned to transmitter/receivers. Data messages can be encoded and transmitted multiple times, at an increased power level, from a control station to a transmitter/receiver over the appropriate data slots in each message frame. The selected TDMA frames are preferably slow associated control channel frames. Also, short alphanumeric messages can be transmitted over the broadcast control channel of a digital radiocommunication link, or another communication channel consisting of one or more slots from successive frames in a TDMA communication link. An increase in transmission power is used in combination with repetition to increase effective signal margin without complications in the mobile unit design, significant delay, or co-channel interference. Where a more significant increase in signal margin is desired, when a longer message is required, or for voice messages, the message may be stored and the mobile unit alerted of the message.
摘要:
A method and system for increasing the signal margin of a radiocommunication link to provide a short message service which is reliable, even under non-ideal conditions. According to the method, an increase in transmission power is used in combination with bit repetition to increase signal margin without complications in the mobile unit design, significant delay, or co-channel interference. Where a more significant increase in signal margin is desired, when a longer message is required, or for voice messages, the message may be stored and the mobile unit alerted of the message.
摘要:
A method and system for increasing the signal margin of a radiocommunication link to provide a short message service which is reliable, even under non-ideal conditions. According to the method, short alphanumeric messages can be transmitted over the broadcast control channel of a digital radiocommunication link, or another communication channel consisting of one or more slots from successive frames in a TDMA communication link. An increase in transmission power is used in combination with repetition to increase effective signal margin without complications in the mobile unit design, significant delay, or co-channel interference. Where a more significant increase in signal margin is desired, when a longer message is required, or for voice messages, the message may be stored and the mobile unit alerted of the message.
摘要:
A satellite broadcasts radio programs to mobile and fixed receivers at various locations. Ground stations supplement the satellite broadcasts in areas where the satellite signal may be shadowed. Likewise, the satellite signal supplements the terrestrial transmissions in areas with marginal terrestrial signal strength. Ground stations and a satellite transmit the same digital symbol stream over a same frequency spectrum. The symbol streams arrive in each service area of the ground stations with a relative delay that is within a window for which a receiver is adapted to decode efficiently. Spectral efficiency is achieved by allowing the ground stations to share the same frequencies as the satellites.
摘要:
A communication system (20) comprises a transmitter (22) and a receiver (24). The transmitter (22) comprises a source of information symbols (30); a pulse shaping wave function generator (32); and a combiner (34) configured to express the information symbols received from the source as signals which are shaped in time and frequency domains by the wave function. The pulse shaping wave function generator (32) is configured to provide a wave function which has the Nyquist property and has a same shape as its own Fourier transform. The combiner (34) is configured to combine the wave function with a stream of digital data symbols to produce a filtered stream for transmission by the transmitter.
摘要:
A method and apparatus for efficiently providing a large volume of channel feedback, e.g., for OFDM MISO and MIMO systems, is described herein. To that end, a mapping unit in an OFDM transceiver maps channel feedback values, e.g., received reference signal values or channel estimates derived therefrom, on a one-to-one basis to individual transmission subchannels. More particularly, the mapping unit maps a feedback value, e.g., the received reference value or a channel estimate derived therefrom, to a single transmission subchannel of an outgoing OFDM signal. For example, the mapping unit may map the feedback value to an input of a frequency transform unit, such as an inverse discrete Fourier transform unit, to map the feedback value to a single transmission subchannel comprising an OFDM transmission subcarrier. The OFDM transceiver transmits the outgoing OFDM signal to the remote transceiver to provide the feedback value to the remote transceiver.
摘要:
The technology in this application solves these problems (and others) and meets the desirable goals identified above (and others). The technology spreads a signal over an available discontinuous spectrum, such as a radio frequency band, so that the spread signal only occupies the non-contiguous spectrum. In this way, CDMA transmission and reception can be used in a fragmented or non-contiguous spectum that otherwise would not be useable for direct sequence spreading. Spreading over non-contiguous portions of spectrum is preferably performed without producing unacceptable interference in portions of unavailable spectrum located between the allowed spectrum. By avoiding unacceptable interference in portions of unavailable spectrum located between the allowed spectrum, the unavailable spectrum may be used by other users or services.