Ericsson Gmbh

Ericsson Ge Mobile Communications Inc.

Telefonaktiebolaget Lm Ericsson (publ)

Ericsson Ge Mobile Communications Holding Inc.

Ericsson Ge Mobile Communication Holding, Inc.

General Electric Company

Paul W Dent

Sandeep Chennakeshu

Gregory Edward Bottomley

Jacobus C Haartsen

Alex K Raith

Amer A Hassan

Thomas M Croft

Jan E Dahlin

Ross W Lampe, Jr

Ross Warren Lampe

Nils Rutger Rydbeck

Ravinder David Koilpillai

Bjorn Martin Lindquist

Lawrence J Harte

Torbjorn Solve

Alex Krister Raith

Raymond L Toy

Torbjorn Wilson Solve

R David Koilpillai

Bjorn O Ekelund

William J Croughwell

Jim Agne Rasmusson

Darrell G Epperson

Jaap Haartsen

Krister A Raith

Ronald J Johnsen

Bj&ouml;rn Lindquist

Philippe M Charas

Alf J Larsson

Magnus Ewerbring

Bjorn Olof Ekelund

A method for determining the position of a mobile radio telephone in a satellite communication system is disclosed. First, a mobile radio telephone scans a plurality of paging channels and measures the signal strength of the paging channels. The mobile radio telephone then selects the paging channel with the strongest signal strength and decodes the information broadcasted on the selected channel. The information contained in the paging channel can include frequencies or timeslots of paging channels in surrounding spot beams. The mobile station then measures the signal strength of paging channels in surrounding spot beams and quantizes the measurements to determine a coarse position of the mobile radio telephone.

Position registration for cellular satellite communication systems

A method for processing a signal modulated with information symbols to account for an additive offset and slope is disclosed. First, an initial estimate of offset and slope is made and hypotheses of all possible values of a sequence of one or more information symbols are then made. For each of said hypotheses, the associated data symbol sequence is used to make an improved estimate of offset and slope and the improved estimate of offset and slope are stored against each of the hypotheses. For each hypothesis, the improved estimate of offset and slope is used in calculating an expected signal value and a mismatch between a sample of the modulated signal and the expected value is computed. The hypotheses are then sequentially extended by one symbol, the slope and offset estimates are updated and the mismatches are accumulated to form a path metric value for each extended hypothesis, and resolving between said hypotheses based on said path metric values using a Viterbi Sequential Maximum Likelihood Sequence Estimation process to produce a most likely hypothesis of said modulated information symbols substantially unimpaired by said additive slope and offset.

Slope drift and offset compensation in zero-if receivers

A method for determining the position of a mobile radio telephone in a satellite communication system includes a mobile radio telephone scanning a plurality of paging channels and measuring the signal strength of the paging channels. The mobile radio telephone then selects the paging channel with the strongest signal strength and decodes the information broadcasted on the selected channel. The information contained in the paging channel can include frequencies or timeslots of paging channels in surrounding spot beams. The mobile station then measures the signal strength of paging channels in surrounding spot beams and quantizes the measurements to determine a coarse position of the mobile radio telephone.

Method of directing a call to a mobile telephone in a dual mode cellular-satellite communications network

A digital beamforming network for transmitting a first number of digital information signal using a second number of antenna array elements is disclosed. Assemblers are used for assembling one information bit selected from each of the information signals into a bit vector. Digital processors have an input for the bit vector and a number of outputs equal to the second number of antenna elements and process the bit vector. Finally, modulation waveform generators coupled to each of the second number of outputs generate a signal for transmission by each antenna element.

Digital beamformer for receiving a first number of information signals using a second number of antenna array elements

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.

High power short message service using dedicated carrier frequency

A secure radio personal communication system and method includes a base station which relays cellular verification signals between a wide area cellular network and a cellular terminal via the wire telephone network. Thus, cellular telephone calls which are routed to a cellular terminal via a base station, when the cellular terminal is within a local region covered by the base station, may be exchanged between the cellular network and cellular terminal over the wire telephone network. Calls from the wide area cellular network which are routed through the base station can thus employ the same security systems and methods which are employed by the wide area cellular network. Signals between the base station and the cellular terminal are preferably exchanged when the cellular terminal is parked in the base station. Verification and encryption signals may be exchanged. The same signals may be used for enhanced security when the base station is relaying wire network calls to the cellular terminal when the cellular terminal is in the local region. Alternatively, separate verification and encryption protocols may be used.

Secure radio personal communications system and method

Apparatus for performing multiplication of a vector of multi-bit values by a matrix of multi-bit coefficients

A method of directing a call to a mobile telephone in a dual mode cellular satellite communications network is disclosed. An alert signal is transmitted to the mobile telephone using base stations of the cellular network if the mobile telephone is currently registered as active in a cellular network. When the alert signal is received at the mobile telephone, the mobile telephone transmits a response to the cellular network as an acknowledgement. When an acknowledgement is not received by the cellular network within a defined period of time, the cellular network transmits the last known location of the mobile telephone to the satellite earth station. Upon receipt of the last known location of the mobile telephone, the satellite earth station using the last known location determines a satellite antenna beam most likely to be received by the mobile telephone and transmits an alert signal to the mobile telephone via the satellite using the antenna beam.

Method of directing a call to a mobile telephone in a dual mode cellular satellite communication network

Radiocommunication systems and methods for minimizing co-channel interference are disclosed. The systems and methods are applicable to, for example, landmobile communications, satellite communication systems and hybrids thereof. Signal processing using matrix models of received and transmitted signals provides for minimized interference.

Cellular/satellite communications system with improved frequency re-use

Methods and systems for processing signals in radio communication systems are described which include processes for handling co-channel interference while reducing the number of Viterbi states being processed. A spatial analogy to the Viterbi MLSE process is provided. Both the uplink and downlink cases are described.

Joint demodulation using spatial maximum likelihood

Paging systems typically include a network of ground stations or orbiting satellites equipped with transmitters and antennas for transmitting paging messages to small, battery-operated paging receivers that are worn about the person, known as pagers. Conventional pagers are receive-only devices and the network receives no confirmation that paging has been successful. The present invention includes the provision of two-way pagers that contain a transmitter for transmitting an acknowledgment confirming reception of a paging message, and a network of receiving stations able to receive said acknowledgments. The network makes use of advanced phased-array antenna signal processing techniques to render the return link operable with much less transmitter power in the portable unit than employed by the base station.

Two-way paging system and apparatus

A method and apparatus of communicating information using Time Division Multiple Access and adaptive transmission and reception are disclosed. Signal bursts are transmitted from TDMA transmitters to a TDMA receiver wherein the transmitter codes the information and transmits coded information to the receiver using at least one of two timeslots of a plurality of timeslots in a repetitive TDMA frame period. Both of the two timeslots are received whether or not the transmitter has transmitted using one or two timeslots and the received signals are classified as intended and non-intended. Successively received signals classified as intended are then assembled into a block for decoding to reproduce the information.

Dual mode satellite/cellular terminal

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.

High-penetration transmission method for a radiocommunication system

A transmitter receives information for transmission to a receiver over a communication channel. A cyclical redundancy checking (CRC) code circuit encodes the information with CRC code for error detection purposes. The CRC coded information is provided to a code switch. The code switch provides the CRC coded information to either a first code circuit or a second code circuit for forward error correction (FEC) coding. The first code circuit may, for example, encode the information using a FEC Code 1, such as convolutional coding, and the second code circuit may encode the information using a FEC Code 2, such as repetition coding. The code switch selects either the first or second code circuit based on detected characteristics of the channel. The channel characteristics may be obtained from a channel estimation circuit, may be obtained from an error feedback signal I.sub.3 from the receiver or may be obtained from a combination of both. After the code switch selects the first or second code circuit, the information is appropriately coded to produce a coded signal which is transmitted over the channel by a transmission circuit.

Transmitter method and transmission system using adaptive coding based

A delay spread is created in a digital radio signal to reduce the coherence bandwidth and facilitate frequency hopping to reduce the effect of fading losses within an enclosed propagation environment The delay spread is introduced into the signal in several ways. One technique disclosed employs a transmitter with two separate antennas one of which transmits the digital signal and the other of which transmits the same signal after a phase delay has been introduced into the signal. The carrier frequency of the signals is hopped between at least two frequencies and the receiver processes the resulting signals. In another embodiment, a single transmit antenna is used but the signal is received by two different antennas with the output signal from one of those antennas being phase delayed before combining it with the other prior to processing by the receiver circuitry. Phase delay is also introduced at baseband into the signals to be transmitted by rotating the I and Q components of the waveforms before modulation.

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Stehag, Sweden

Paul W Dent