Abstract: A method of reusing frequency bands between base stations of a terrestrial mobile communications network and a satellite communications network, comprising allocating the frequency bands using integrated resource management and other mitigation techniques in a such a way as to minimise interference between both the systems, thus making optimum usage of valuable frequency spectrum.

Abstract: A method of reusing frequency bands between base stations of a terrestrial mobile communications network and a satellite communications network, comprising allocating the frequency bands using integrated resource management and other mitigation techniques in a such a way as to minimise interference between both the systems, thus making optimum usage of valuable frequency spectrum.

Abstract: A method of reusing frequency bands between base stations of a terrestrial mobile communications network and a satellite communications network, comprising allocating the frequency bands using integrated resource management and other mitigation techniques in a such a way as to minimise interference between both the systems, thus making optimum usage of valuable frequency spectrum.

Abstract: A method of reusing frequency bands between base stations of a terrestrial mobile communications network and a satellite communications network, comprising allocating the frequency bands using integrated resource management and other mitigation techniques in a such a way as to minimize interference between both the systems, thus making optimum usage of valuable frequency spectrum.

Abstract: A method and apparatus are disclosed for a system where a user terminal 11 can communicate with satellites 9A-C, the satellites 9A-C can communicate with earth stations 7A-E which in turn can communicate with the terrestrial telephone system 1. The user terminal can register with one of the earth stations 5C which has an associated mobile satellite switching center 5C which acts as a gateway into the terrestrial system 1. When attempting to contact the user terminal 11 from the terrestrial system 1 the mobile satellite switching center 5C of visitor registration, if it cannot make the contact itself, instructs other earth stations 5, 7, in turn, according to different methods of alternative earth station 7 selection, until contact is made, and then routes all voice messages 21 through itself 5C to retain the single and original gateway into the terrestrial system 1.

Abstract: A method of reusing frequency bands between base stations of a terrestrial mobile communications network and a satellite communications network, comprising allocating the frequency bands using integrated resource management and other mitigation techniques in a such a way as to minimize interference between both the systems, thus making optimum usage of valuable frequency spectrum.

Abstract: In order to use spectrum more efficiently in a TDMA mobile telephone system, signal measurements are carried out by a mobile station outside of the normal frame structure, i.e. idle frames for signal measurement are not provided. When a diversity or a double data rate mode is being used, a communication burst period is stolen to provide time for the measurements. The invention is particularly applicable to satellite mobile telephone systems in which the burst length is less than the signal propagation time.

Abstract: A communication station for generating or receiving an angularly dispersed array of radiation beams, comprising an array of radiating elements (100) defining an array antenna (1); and a beam former (120), the beam former comprising a passive network having a first side (X) carrying a plurality of beam ports for electrical signals corresponding to the beams and a second side (Y) carrying a plurality of antenna ports corresponding to the radiating elements, each beam port being connected to a plurality of antenna ports via a network (50) of power divider (52) and phase shifter (53) components, the phase shifts of which are in integer multiples of a predetermined constant, so as to generate the array of beams; in which the array antenna (1) has triangular or hexagonal symmetry and the array of beams has triangular or hexagonal symmetry.

Abstract: A satellite communications system comprises satellites 9A-C, earth stations 7A-E, user terminals 11 and controlling gateways 3 in the form of mobile satellite switching centers 5A-E. Access with a user terminal 11 may be gained to a terrestrial telephone system 1 by earth stations 7A-E contacting the satellites 9A-C and by the satellites contacting the user terminals 11. The satellites 9A-C periodically broadcast messages indicative of the earth station 7A-E with which they are instantly in contact. The user terminal 11 listens to and logs these broadcasts to keep a list of the relative number of times each earth station 7A-E can be heard. When calling into the system, the user terminal pages earth stations in descending order of number of entries in the log. When in contact, the user terminal 11 sends the log to the system. When subsequently trying to contact the user terminal 11, the system uses earth stations in descending order of number of entries on the log, last received from the user terminal.