Abstract: A beam layout is optimised for a given traffic distribution and network state by determining optimum beam centre positions and generating a beam layout so as to meet system requirements and minimise the distances of locations within a coverage area from the optimum beam centre positions. Adjacent beams in low traffic areas may be merged.

Abstract: A beam layout is optimised for a given traffic distribution and network state by determining optimum beam centre positions and generating a beam layout so as to meet system requirements and minimise the distances of locations within a coverage area from the optimum beam centre positions. Adjacent beams in low traffic areas may be merged.

Abstract: A container tracking system includes a plurality of metallic containers arranged with substantially parallel sides having a gap therebetween, and at least one RF transmitter having an antenna located within the gap and arranged to excite a transverse electromagnetic (TEM) wave transverse to the parallel sides.

Abstract: A method of forward link power control in a communications system comprises: grouping a plurality of user terminals into a plurality of groups, at least one of which comprises more than one of the user terminals; for each said group, determining a corresponding forward link power level required to satisfy an aggregate demand of the group; and assigning one or more forward link carriers to the group, with the corresponding power level.

Abstract: A mobile communication system comprises: a mobile platform (1) having a plurality of interfaces (2) to a respective plurality of mobile communication networks (6), and a router (5) for selectively connecting one or more communications devices (4) within the mobile platform (1) to one or more of the interfaces (2), for communication over the respective mobile communication networks (6); and a central core (10), common to each of the mobile communication networks (6), including a resource manager (11) arranged to allocate communication resources to the link interfaces (2); wherein the resource manager (11) is responsive to resource requests (S3) from the mobile platform (1) and to network conditions in the mobile communication networks (6).

Abstract: A combined satellite and terrestrial communication system may include at least one satellite earth station, for communication via a satellite with a plurality of terminals using one or more satellite links; a plurality of terrestrial stations, for communication with the plurality of terminals using one or more terrestrial links; wherein the satellite links overlap or coincide in frequency with the terrestrial links; and each of the terminals includes means for inhibiting interference between the satellite links and the terrestrial links.

Abstract: A wireless multiple access method allows multiple transmitters to access the same channels so that substantial interference occurs. The transmitters use low rate turbo coding and the receiver uses multi-user detection to separate and decode the transmissions. Different propagation and/or transmission characteristics between the transmitters help to distinguish the transmissions at the receiver. The transmitters may add random variation to their transmission timing, power and/or frequency to assist with decoding.

Abstract: A method of monitoring at least one beam of a satellite, the at least one beam being directed at a body around which the satellite orbits, the method comprising monitoring the at least one beam using a monitoring satellite which orbits around the body.

Abstract: In a bandwidth allocation protocol for a mobile communications network, mobile terminals indicate the total quantity of data awaiting transmission, the maximum delay time of the most urgent portion of the data, and the maximum delay time of the least urgent portion. If a collision occurs between transmission by two mobiles, the mobiles wait for an interval controlled by the network before attempting another contention-based access transmission. The network periodically varies the contention-based access capacity available according to the observed usage level and/or collision rate in the previously allocated contention-based access capacity. The network analyses the forward traffic to individual mobiles and predicts likely return bandwidth requirements.

Abstract: In a carrier allocation scheme for a cellular communications system, cells are divided into groups of different types (CG1, CG2, CG3, CG4) and carriers (fxyz) are divided into sets (f1yz, f2yz, f3yz, f4yz) allocated respectively to the different types. Carriers may be re-used between different groups of the same type, and optionally within a group, subject to a minimum re-use distance rule. The allocation patterns may be varied independently between different groups of the same type. The scheme may be adapted to the demand for carriers over a predetermined period. Different allocation schemes applied to different carriers may be overlaid on the same cells. Different allocation schemes may be applied to different cells, provided that the minimum re-use distance rule is obeyed between schemes. The scheme may be applied to spot beams of a satellite communications system, or cells of a terrestrial cellular system.

Abstract: In a spectrum allocation method in a cellular communication system, a cell pattern is divided into clusters each containing a plurality of adjacent cells. A pool of forward and return link bearers is allocated to each cluster and may be shared among cells within the cluster. Bearers are reused between blusters having a sufficiently high mutual isolation. Preferably, the same time slot in a return link bearer is allocated to multiple users within the cluster. The receiver of the shared return link bearer uses multi-user detection techniques to separately decode the signals from each user sharing a time slot, using the spatial diversity of the individual cells.

Abstract: A system for providing real-time television broadcasts to aircraft 4 via satellite 2 is described. The broadcast signal 11 is transmitted to the aircraft 4 together with a communications signal 10, forming part of an existing communications network air interface. The system separates the communications signal 10 from the broadcast signal 11 and enables the real-time broadcast to be displayed on-board the aircraft.

Abstract: A satellite has a depletion detector arranged in a propellant line such that, when depletion is detected, the amount of propellant remaining in the propellant lines is sufficient to dispose of the satellite, and may include a margin sufficient for 6-12 months of stationkeeping. This provides a simple and reliable method of determining when decommissioning is required.

Abstract: In a wireless communications system, transceivers transmit short bursts to a base station, which determines timing corrections from the time of receipt of the burst and transmits the timing corrections to the respective transceivers. In one aspect, the base station indicates to the transceivers a plurality of time slots, each transceiver selects one of the time slots at random, formats a burst including an indicator of the selected time slot and transmits the burst in that slot. In another aspect, the base station transmits to each transceiver a timing uncertainty value, which determines how the timing correction will be modified by the tranceiver as the interval since last receiving a timing correction increases. Data bursts are transmitted in a format comprising a first unique word, a content field and a second unique word, in that order. The bursts are transmitted in a TDMA channel format which can accommodate both short and long bursts in a block format of constant periodicity.

Abstract: In a bandwidth allocation protocol for a mobile communications network, mobile terminals report their bandwidth requirements to the network, while the network controls the amount of bandwidth that is used by the mobiles in reporting their bandwidth requirements. The mobiles indicate the total quantity of data awaiting transmission, the maximum delay time of the most urgent portion of the data and the maximum delay time of the least urgent portion. If a collision occurs between transmission by two mobiles, the mobiles wait for an interval controlled by the network before attempting another contention-based access transmission. The network periodically varies the contention-based access capacity available according to the observed usage level and/or collision rate in the previously allocated contention-based access capacity. The network analyses the forward traffic to individual mobiles and predicts the return bandwidth requirements which are likely to result from the forward traffic.

Abstract: A satellite communications system provides a communications service to a mobile terminal on which different communications applications may be run. Calls are set up between any of the applications via a satellite to a network management centre which provides different service adaptors which adapt the calls to different types of service provided over terrestrial networks, such as telephony, facsimile, internet or ATM services. The bandwidth allocated to each call over the satellite link may be varied during the call according to demand either from the relevant application or from the network management centre. Multiple calls may be connected concurrently to or from different applications running on the mobile terminal. A maximum bandwidth is allocated to each call. Efficient use is thereby made of the limited bandwidth available over the satellite, according to the instantaneous bandwidth requirements of different applications.

Abstract: In a frame sync method, a receiver searches for the presence of an N-symbol long unique word pattern. For each possible frame sync detected, the receiver proceeds to demodulation and FEC processing. After each iteration of the FEC decoder, the detected unique word pattern is compared to the expected one and the frame sync is detected if the number of unique word errors has decreased.

Abstract: A set of formats and protocols is proposed for a satellite communications system. In these formats, a pilot signal (PS) is inserted after every 25 or 29 data symbols. The formats consist of SCPC frames (F) which may contain either data (D) and in-band signaling information (SU), or only signaling information (SU). In either case, the contents of each frame (F) are error-correction coded before transmission with the same coding rate. Each data frame (F) carries the data content of an integral number of input user data frames (M), each of which comprises four subframes. Different symbol transmission rates are used for different input data rates, the symbol transmission rates being selected so that their different synchronizing clock rates can easily be obtained from a common clock. Data bursts may be preceded by a constant power level preamble (P). The formats and protocols satisfy the requirements of a high data rate satellite communications system.

Abstract: In a frame sync method, a receiver searches for the presence of an N-symbol long unique word pattern. For each possible frame sync detected, the receiver proceeds to demodulation and FEC processing. After each iteration of the FEC decoder, the detected unique word pattern is compared to the expected one and the frame sync is detected if the number of unique word errors has decreased.

Abstract: A satellite communications system provides a communications service to a mobile terminal on which different communications applications may be run. Calls are set up between any of the applications via a satellite to a network management center which provides different service adaptors which adapt the calls to different types of service provided over terrestrial networks such as telephony, facsimile, internet or ATM services. The bandwidth allocated to each call over the satellite link may be varied during the call according to demand either from the relevant application or from the network management center. Multiple calls may be connected concurrently to or from different applications running on the mobile terminal. A maximum bandwidth is allocated to each call. Efficient use is thereby made of the limited bandwidth available over the satellite, according to the instantaneous bandwidth requirements of different applications.