Inmarsat Global Limited

Inmarsat Limited

David Denis Mudge

Paul R Febvre

Panagiotis Fines

Edward Arthur Jones

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. The network stores associations between forward and return frequency channels, so that when a mobile receiving a forward frequency channel request return capacity, the network preferentially assigns return bandwidth to the mobile in one or more of the associated return channels.

Method and apparatus for controlling transmissions in communication systems

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.

Method and apparatus for timing correction in communications systems

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. The network stores associations between forward and return frequency channels, so that when a mobile receiving a forward frequency channel request return capacity, the network preferentially assigns return bandwidth to the mobile in one or more of the associated return channels.

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London, United Kingdom

David Denis Mudge