Ericsson Gmbh

Barbara Davis Molnar

Amer A Hassan

Rajaram Ramesh

Karl James Molnar

Ali S Khayrallah

Jiann-Ching Guey

Sandeep Chennakeshu

Nils Rutger Rydbeck

R David Koilpillai

Stanley L Reinhold

Eric Stasik

A diversity scheme for allowing a transmitter/receiver, such as a mobile unit in a mobile telecommunications system, to exchange communication signals with more than one control station, such as a base station or satellite. According to an exemplary embodiment of the diversity scheme, the mobile unit scans for the control channel of a second satellite during idle time slots while communicating with a first satellite during active time slots. Once the mobile unit detects a control channel from a second satellite, the mobile unit stores synchronization information and establishes a communication link with the second satellite if shadowing or other severe fading causes signal quality over a communication link established with a first satellite to fall below a threshold level. The diversity scheme also allows the mobile unit to communicate simultaneously with two satellites, using alternate TDMA frames.

Satellite diversity scheme

A message, e.g., a control message, a short message, a voice message or a data message, is transmitted on at least one of a first communications channel having a first redundancy level or a second communications channel having a second, higher redundancy level. A radio communications signal is received on one of the first communications channel and the second communications channel. The received radio communications signal is demodulated to recover the message using a first demodulation scheme if the radio communications signal is received on the first communications channel and using a second demodulation scheme if the radio communications signal is received on the second communications channel. According to an aspect of the invention, the received radio communications signal is coherently demodulated if the radio communications signal is received over the first communications channel and non-coherently demodulated if the radio communications signal is received over the second communications channel. According to another aspect, the message is transmitted on the first communications channel using a first modulation constellation, and transmitted on the second communications channel using a second modulation constellation representing a subset of the first modulation constellation. In other embodiments of the present invention, a first radio communications signal is transmitted representing the message encoded according to one of a first code or a second code that represents a concatenation of the first code and an additional code, such as an orthogonal code or a quasi orthogonal code. Related systems and apparatus are also described.

Apparatus and methods for providing high-penetration messaging in wireless communications systems

In a wireless communications system, information is communicated over one of a first communications channel having a first redundancy level or a second communications channel having a second redundancy level based on a determination of communications quality for at least one of the channels. In embodiments of the present invention, communications occur over a first channel, e.g., a &ldquo;standard&rdquo; channel until a measure of communications quality for that channel, such as bit error rate or frame error rate, meets a predetermined criterion. When the communications quality meets the predetermined criterion, communications shifts to a &ldquo;robust&rdquo; high-penetration channel that utilizes substantially the same amount of spectral resource as the first channel but provides significantly increased redundancy. In other embodiments, a terminal, e.g., a cellular radiotelephone or other radio terminal, registers with a wireless communications system via one of a standard broadcast control channel or a high-penetration broadcast control channel, and switches therebetween based upon a determination of communications quality for the standard broadcast control channel. For example, the terminal may switch to the high-penetration broadcast control channel upon failure to acquire the standard broadcast control channel in a disadvantaged reception area.

Wireless communications systems with standard and robust services and methods of operation thereof

Exemplary embodiments of the present invention describe terminal position location methods and systems. Relative powers of nearby spot beams which are generated by array antennas are determined. For example, powers from six neighboring spot beams relative to a center spot beam within which a mobile station is currently operating, can be measured relative to the power of the center spot beam. Using information from these measurements, the mobile stations position can be determined using, for example, an exponential model of the spot beam pattern.

Position determination using multiple base station signals

A mobile-link system for a radio communication system including a first mobile-link assembly, a second mobile-link assembly, and a satellite feeder-link assembly located in a satellite; and an earth feeder-link assembly located in an earth station. The first mobile-link assembly receives mobile uplink signals including zone-one uplink signals transmitted from mobile stations located in a first zone of a coverage area and zone-two uplink signals transmitted from mobile stations located in a second zone of the coverage area, and outputs received zone-one uplink signals and received zone-two uplink signals. The second mobile-link assembly receives mobile uplink signals transmitted from mobile stations in the coverage area, and outputs received zone-two uplink signals and not zone-one uplink signals. The second mobile link assembly also transmits mobile downlink signals to at least the first and second zones of the coverage area. The satellite feeder-link assembly conveys the received mobile uplink signals to the earth feeder-link assembly by transmitting feeder-link downlink signals corresponding to the received mobile uplink signals. The earth feeder-link assembly is connected to and couples the mobile-link system to a communication network. The earth feeder-link assembly includes a combiner for combining the feeder-link downlink signals such that the zone-two uplink signals received by the first and second mobile link assemblies are combined to produce diversity resultant signals.

Mobile-link system for a radio communication system wherein diversity

A coding system for error protecting both insignificant and significant symbols of a digital message to be transmitted from a transmitter to a receiver of a digital system. Error protection for both insignificant and significant symbols is provided by coding at the transmitter both significant and insignificant symbols of message blocks forming the digital message. The symbol rate of the coded signal to be transmitted is reduced and unequal error protection is provided to the significant symbols by puncturing a selected number of insignificant symbols of each codeword of the coded signal. At the receiver, a correction determination is made for each received codeword as to whether the erasures and errors of the received codeword are correctable. The correction determination is a function of the number of errors, number of erasures, and the minimum distance of the code. Based on this correction determination, the received codeword is depunctured and decoded.

Punctured coding system for providing unequal error protection in a

A digital communication system having a punctured convolutional coding system and method. The digital communication system includes a coder for coding a digital input to be transmitted from a transmitter and a decoder for decoding the coded input received at the receiver. The coder includes a convolutional coding circuit of rate k/n for outputting a convolutional coded output and a puncturing circuit for puncturing the convolutionally coded output to achieve a punctured code rate of z/q, where z=.gamma.k. The puncturing circuit punctures the convolutional coded output according to a deleting pattern chosen to have a bit length of L=p.gamma.n, where p.gtoreq.2. The puncturing circuit outputs a punctured output at punctured code rate of z/q and the punctured output is transmitted to the receiver. The receiver decodes the transmitted punctured output and outputs a decoded output.

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Cary, NC, United States of America

Barbara Davis Molnar