Roke Manor Research Limited

Inmarsat Limited

Michael J McTiffin

Nobuyuki Kawai

David Randall

Hok Shuen Wong

Roderick Leonard Wallace Stevens

Paul Roderick Webb

A communication system for the mutual interconnection of a plurality of lower traffic level (5 Terabit) switch nodes via a relatively higher traffic level (Petabit) connection bus, which system comprises in operative association with each node, a two part TDM optical data management interface, wherein a first of the two parts comprises a time slot resequencer which serves to provide for the transmission of data from its associated node to the bus, and wherein a second of the two parts comprises a time slot specific combiner which serves for the transmission of data from the bus to its associated node, each node and the bus having independent data scheduling.

Communication systems

Data relating to the status of usersin a mobile communications system is broadcast via satellitefrom a network registerto local registersin an HDLC format. Each of the local registersrequests retransmission of any HDLC frames which are incorrectly received. The network registerrecords the earliest transmitted frame not yet acknowledged by all of the local registers and inhibits transmission of new frames if they fall outside a transmission window relative to the earliest transmitted frame. The network registerpolls the local registersfor retransmission requests and the local registersalso send unsolicited requests to the network register. The network registeronly retransmits a frame once if multiple requests for that frame are transmitted within a predetermined period. When a new local registerenters the broadcast reception group, the network registerinforms the new local registerwhich new frame will next be transmitted. The number of bits used for frame sequence numbers is greater than that defined in the HDLC protocols.

Method and apparatus for transmitting data

A timing recovery apparatus for asynchronous residual time stamping is disclosed. The timing recovery apparatus is placed at the timing domain boundaries for extending the use of synchronous residual time stamping into a new timing domain and for calculating the value indicative of the number of complete source network clock cycles in a predetermined time period which is loaded into a counter. When the counter reaches a predetermined value, a latch connected to a further counter contains a new residual time stamp value.

Timing recovery apparatus

A communication system for transmission of data from an ATM network to a mobile radio system having an interface apparatus coupled therebetween which is operative to remove from the header of each ATM cell entering the system from the network VPI and VCI data. A translator, responsive to the VPI and VCI data, appropriately codes data formed of the remainder of each cell from which the VPI and VCI data has been removed so that it will be received by a mobile user having an address as indicated by the VPI and CPI data. A second translator responsive to codes corresponding to user addresses produces corresponding VPI and VCI data. A unit for recombining the VPI and VCI data with data formed of the remainder of the cell from which it was removed is provided to thereby produce whole cells suitable for transmission from the system to a mobile terminal.

An asynchronous transmission mode (ATM) system adapted for use with mobile terminals, the system comprising a mobile network interface unit connected to a network, a plurality of base stations connected to the network, and at least one mobile terminal arranged to communicate with the base stations over a radio link, the network being arranged to connect the mobile network interface unit and the base stations, said connections being defined by a virtual path identifier, a unique virtual channel identifier being allocated at set up of a call or connection by the mobile network interface unit, for identifying a call or connection associated with a mobile terminal being handled within an area controlled by the mobile network interface unit, the virtual channel identifier being placed in a virtual channel identifier field of ATM cell carrying user data associated with the call or connection.

Growing community of inventors

Winchester, United Kingdom

Michael J McTiffin