Arrangement for synchronizing a plurality of base stations
First Claim
Patent Images
1. A communications system comprising:
- a plurality of communications base stations each having operations synchronized to a received synchronization signal;
a plurality of communications links connected to the plurality of base stations, at least one link being connected to each base station;
a controller connected to the plurality of links for sending communications traffic to the base stations via the links, and using an ISDN protocol to transport the traffic on the links; and
means in the controller for sending the synchronization signal simultaneously to all of the base stations via the links to synchronize the operations of the base stations, by embedding the synchronization signal in the ISDN protocol on the links includingmeans for causing otherwise-unused bits of the ISDN protocol to transport the synchronization signal on the links.
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Accused Products
Abstract
In a wireless telecommunications system (FIG. 1), over-the-air operations of a plurality of base stations (11 ) are synchronized via a synchronization signal that is embedded in the normal communications protocol that is used to convey traffic between a control switch (12) and the base stations. In the physical-layer protocol of the ISDN S or T basic-rate interface, the S or M bits are employed to conduct the synchronization signal. The synchronization signal is generated in the control switch and broadcast therein to port circuit packs (310) via a synchronization bit of a dedicated time-slot of a TDM bus (303).
169 Citations
23 Claims
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1. A communications system comprising:
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a plurality of communications base stations each having operations synchronized to a received synchronization signal; a plurality of communications links connected to the plurality of base stations, at least one link being connected to each base station; a controller connected to the plurality of links for sending communications traffic to the base stations via the links, and using an ISDN protocol to transport the traffic on the links; and means in the controller for sending the synchronization signal simultaneously to all of the base stations via the links to synchronize the operations of the base stations, by embedding the synchronization signal in the ISDN protocol on the links including means for causing otherwise-unused bits of the ISDN protocol to transport the synchronization signal on the links. - View Dependent Claims (2)
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3. A communications base station having operations synchronized to a received synchronization signal, comprising:
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means for connecting to at least one communications link to receive communications traffic transported on the link by an ISDN protocol; and means coupled to the connecting means for extracting the synchronization signal from among the received communications traffic, which synchronization signal is transported on the link along with the traffic by being embedded in the ISDN protocol, including means for extracting from otherwise-unused bits of the ISDN protocol the synchronization signal, which is transported by the otherwise-unused bits of the ISDN protocol on the link. - View Dependent Claims (4, 5)
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6. A controller for at least one communications base station having operations synchronized to a received synchronization signal, comprising:
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means for connecting to at least one communications link that connects to the at least one base station, for sending communications traffic to the at least one base station via the at least one link, the connecting means using an ISDN protocol to transport the traffic on the at least one link; and means coupled to the connecting means, for sending the synchronization signal simultaneously to all base stations of the at least one base station via the at least one link to synchronize the operations of the at least one base station by embedding the synchronization signal in the ISDN protocol on the at least one link, including means for causing other, wise-unused bits of the ISDN protocol to transport the synchronization on the at least one link. - View Dependent Claims (7, 8, 9, 10)
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11. A controller for a plurality of communications base stations having operations synchronized to a received synchronization signal, comprising:
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a time-division multiplexed (TDM) bus having a repeating plurality of time slots including a predetermined time slot, at least some of the time slots carrying communications traffic; means connected to the TDM bus for periodically transmitting the synchronization signal on the TDM bus in the predetermined time slot; a plurality of port circuit means connected to the TDM bus, each for interfacing to the TDM bus at least one communications link of a plurality of communication links that connect to the plurality of base stations, each port circuit means for transmitting communications traffic carried by at least one time slot of the TDM bus, in an information-carrying frame repeatedly outgoing on the at least one link; means for distributing, to the plurality of port circuit means, a repeating framing clock signal that has a repetition rate higher than a rate of repetition of the information-carrying frame; means for causing all of the plurality of port circuit means to synchronize their transmissions of sequential instances of the information-carrying frame with receipt of same ones of non-sequential instances of the framing clock signal; and means connected to the TDM bus and responsive to receipt of the synchronization signal in the predetermined time slot, for transmitting the received synchronization signal to the plurality of base stations from each port circuit means in a next-outgoing information-carrying frame to synchronize the operations of the plurality of base stations, whereby transmissions by all of the port circuit means of instances of the information-carrying frame that carry the synchronization signal are synchronized with each other so that all of the port circuit means transmit the synchronization signal to the plurality of base stations at a same time. - View Dependent Claims (12, 13, 14, 15, 17)
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16. The controller of claim 16 wherein the predetermined protocol comprises an ISDN protocol.
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18. A method of transporting a synchronization signal to a plurality of communications base stations each having operations synchronized to said synchronization signal received from a controller connected to the base stations by a plurality of links, comprising the steps of:
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sending communications traffic from the controller to the base stations via the links, by using an ISDN protocol to transport the traffic on the links; and sending the synchronization signal from the controller simultaneously to all of the base stations via the links to synchronize the operations of the base stations, by embedding the synchronization signal in the ISDN protocol on the links including causing otherwise-unused bits of the ISDN protocol to transport the synchronization signal on the links. - View Dependent Claims (19)
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20. A method of distributing a synchronization signal in a controller for a plurality of communications base stations having operations synchronized to the synchronization signal, comprising the steps of:
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periodically transmitting the synchronization signal in a predetermined time slot of a time-division multiplexed (TDM) bus having a repeating plurality of time slots including the predetermined time slot; transmitting communications traffic carried by at least one time slot of the TDM bus, from a plurality of port circuits connected to the TDM bus on communications links leading to the plurality of base stations, in an information-carrying frame repeatedly outgoing on each of the links; distributing, to the plurality of port circuits, a repeating framing clock signal that has a repetition rate higher than a rate of repetition of the information-carrying frame; synchronizing transmissions of sequential instances of the information-carrying frame from all of the ports circuits with receipt of same ones of non-sequential instances of the framing clock signal at each of the port circuits; and in response to receipt of the synchronization signal in the predetermined time slot at an arrangement connected to the TDM bus, transmitting the received synchronization signal to the plurality of base stations from each port circuit means in a next-outgoing information-carrying frame to synchronize the operations of the plurality of base stations, whereby transmissions from all of the port circuits of instances of the information-carrying frame that carry the synchronization signal are synchronized with each other so that all of the port circuits transmit the synchronization signal to the plurality of base stations at a same time.
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21. A controller for at least one communications base station having operations synchronized to a received synchronization signal, comprising:
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a time-division multiplexed (TDM) bus having a repeating plurality of time slots including a predetermined time slot, at least some of the time slots carrying communications traffic; means connected to the TDM bus for periodically transmitting the synchronization signal on the TDM bus in the predetermined time slot; port circuit means connected to the TDM bus, for interfacing to the TDM bus at least one communications link that connects to the at least one base station and for transmitting communications traffic carried by at least one time slot of the TDM bus on the at least one link to the at least one base station by using a predetermined protocol to transport the traffic on the at least one link; and means connected to the TDM bus and responsive to receipt of the synchronization signal in the predetermined time slot, for causing the port circuit means to transmit the synchronization signal simultaneously to all of the base stations of the at least one base station to synchronize the operations of the at least one base station, the synchronization signal being embedded in the predetermined protocol on the at least one link. - View Dependent Claims (22, 23)
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Specification