Adaptive synchronization arrangement
DC CAFCFirst Claim
1. A communications system comprising:
- a first unit for receiving incoming communication traffic at times dictated by first clock signals having a nominal frequency and a first phase;
a second unit for transmitting incoming communication traffic at times dictated by clock signals having the nominal frequency;
a third unit for interfacing communications between the first and the second units by transmitting to the first unit incoming communication traffic received from the second unit at times dictated by clock signals having the nominal frequency and having a second phase that is offset by an adjustably fixed amount from the first phase;
a communications medium connecting the second unit with the third unit and conveying communication traffic transmitted by the second unit to the third unit for reception, the communications medium having a fluctuating transmission delay;
first means for determining whether the third unit receives incoming communication traffic from the second unit within predetermined windows of time prior to the times of transmission by the third unit of the received incoming communication traffic; and
second means responsive to a determination that receptions of the incoming communication traffic at the third unit fall outside of the windows for either increasing or decreasing the amount of the offset of the second phase from the first phase to move the receptions into the windows.
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Accused Products
Abstract
A CDMA cellular radio-telephone system (FIG. 2) has switching systems (201) synchronized to public telephone network (100) timing signals (600), and radio telephones (203) and cell base stations (202) synchronized to a different clock (1000). Transmission delays between the cell base stations and the telephone network are variable. Switching systems include digital communications interfaces (264) to the telephone system, whose connections to the telephone system are synchronized to the telephone system, and whose connections to the cells are nominally also synchronized to the telephone system but whose processor (602) operates for each call within predefined windows (1302, 1402) of phase relationships to the operation of the cell that is handling the call, and occasionally adjusts (FIGS. 13-16) its phase relationships to the operation of the telephone system to achieve and maintain its operation within the predefined windows. Packet-switched communications (350) between the cells and the switching systems absorb the phase relationship fluctuations and the timing adjustments in inter-packet intervals. Circuit-switched signal communications between the switching systems and the telephone system absorb the timing adjustments by means of vocoder (604)-implemented slips--bit insertions or deletions--in the communications traffic bit stream.
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Citations
42 Claims
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1. A communications system comprising:
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a first unit for receiving incoming communication traffic at times dictated by first clock signals having a nominal frequency and a first phase; a second unit for transmitting incoming communication traffic at times dictated by clock signals having the nominal frequency; a third unit for interfacing communications between the first and the second units by transmitting to the first unit incoming communication traffic received from the second unit at times dictated by clock signals having the nominal frequency and having a second phase that is offset by an adjustably fixed amount from the first phase; a communications medium connecting the second unit with the third unit and conveying communication traffic transmitted by the second unit to the third unit for reception, the communications medium having a fluctuating transmission delay; first means for determining whether the third unit receives incoming communication traffic from the second unit within predetermined windows of time prior to the times of transmission by the third unit of the received incoming communication traffic; and second means responsive to a determination that receptions of the incoming communication traffic at the third unit fall outside of the windows for either increasing or decreasing the amount of the offset of the second phase from the first phase to move the receptions into the windows. - View Dependent Claims (2, 3)
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4. A communications system comprising:
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a first unit for transmitting outgoing communication traffic at times dictated by first clock signals having a nominal frequency and a first phase; a second unit for transmitting outgoing communication traffic at times dictated by clock signals having the nominal frequency; a third unit for interfacing communications between the first and the second units by transmitting to the second unit outgoing communication traffic received from the first unit at times dictated by clock signals having the nominal frequency and having a second phase that is offset by an adjustably fixed amount from the first phase; a communications medium connecting the second unit with the third unit and conveying communications traffic transmitted by the third unit to the second unit for reception, the communications medium having a fluctuating transmission delay; first means for determining whether the second unit receives outgoing communication traffic from the third unit within predetermined windows of time prior to the times of transmission by the second unit of the received outgoing communication traffic; and second means responsive to a determination that receptions of the outgoing communication traffic at the second unit fall outside of the windows for either increasing or decreasing the amount of the offset of the second phase from the first phase to move the receptions into the windows. - View Dependent Claims (5, 6)
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7. A communications system comprising:
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a first unit for transmitting outgoing communication traffic and receiving incoming communication traffic at times dictated by first clock signals having a nominal frequency and a first phase; a second unit for transmitting received incoming and outgoing communication traffic at times dictated by second clock signals having the nominal frequency; a third unit for interfacing communications between the first and the second units by transmitting to the second unit outgoing communication traffic received from the first unit at times dictated by third clock signals having the nominal frequency and having a second phase that is offset by an adjustably fixed first amount from the first phase, and by transmitting to the first unit incoming communication traffic received from the second unit at times dictated by fourth clock signals having the nominal frequency and having a third phase that is offset by an adjustably fixed second amount from the first phase; a communications medium connecting the second unit with the third unit and conveying communication traffic transmitted by, respectively, the second unit and the third unit to, respectively, the third unit and the second unit for reception, the communications medium having a fluctuating transmission delay; first means for determining whether the second unit receives outgoing communication traffic from the third unit within first predetermined windows of time prior to the times of transmission by the second unit of the received outgoing communication traffic; second means for determining whether the third unit receives incoming communication traffic from the second unit within second predetermined windows of time prior to the times of transmission by the third unit of the received incoming communication traffic; and third means responsive to a determination that either receptions of the outgoing communication traffic at the second unit fall outside of the first windows or receptions of the incoming communication traffic at the third unit fall outside of the second windows for either increasing or decreasing the amount of the offset of either the second phase or the third phase from the first phase to move the receptions that fall outside of their corresponding windows into the corresponding windows. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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15. A call-traffic processing apparatus for a cellular radio-telephone system that includes the apparatus, a communications medium connected to the apparatus and having a fluctuating transmission delay, at least one cell connected to the communications medium and each for transmitting first packets containing first frames of coded incoming call traffic received from a radio telephone to the apparatus across the medium and for transmitting to the radio telephone outgoing call traffic received across the medium from the apparatus in second packets containing second frames of coded outgoing call traffic, and a mobile-telephone switching system for interconnecting cells with each other and with a telephone network by routing a first digital stream of incoming call traffic received from the apparatus to a destination and by routing a second digital stream of outgoing call traffic received from a source to the apparatus, and wherein the first and the second digital streams are synchronized with first clock signals having a nominal frequency and a first phase and derived from the telephone network, and the transmissions of the incoming and the outgoing call traffic by the cell are synchronized with second clock signals having the nominal frequency, the call-traffic processing apparatus comprising:
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outgoing vocoder means for receiving the second digital stream of outgoing call traffic synchronously with the first clock signals, coding the received outgoing call traffic, and transmitting second frames of the coded outgoing call traffic synchronously with third clock signals having the nominal frequency and a second phase that is offset by an adjustably fixed first amount from the first phase, incoming vocoder means for receiving first frames of the coded incoming call traffic synchronously with fourth clock signals having the nominal frequency and a third phase that is offset by an adjustably fixed second amount from the first phase, decoding the received incoming call traffic, and transmitting the second digital stream of incoming call traffic synchronously with the first clock signals; outgoing processing means for receiving the second frames of the coded outgoing call traffic from the outgoing vocoder means, packetizing the received second frames into the second packets, and transmitting the second packets to the cell synchronously with fifth clock signals having the nominal frequency and a fourth phase that is offset by an adjustably fixed third amount from the first phase; incoming processing means for receiving the first packets from the cell, depacketizing the received first packets into the first frames, and transmitting the first frames to the incoming vocoder means synchronously with sixth clock signals having the nominal frequency and a fifth phase that is offset by an adjustably fixed fourth amount from the first phase; clock signal generating means for deriving the third, the fourth, the fifth, and the sixth clock signals from the first clock signals; first means for determining whether the incoming processing means receive the first packets within first predetermined windows of time prior to the times of transmission of the first frames by the incoming processing means to the incoming vocoder means; second means for determining whether the cell receives the second packets within second predetermined windows of time prior to the times of transmission by the cell of the received outgoing call traffic to the mobile telephone; and third means responsive to a determination that either receptions of the first packets fall outside of the first windows or receptions of the second packets fall outside of the second windows for causing the clock signal generating means to either increase or decrease the amounts of the offsets of either both the second and the fourth phases or both the third and the fifth phases, with respect to the first phase, to move the packet receptions that fall outside of their corresponding windows into the corresponding windows. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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22. A method of operating a communications system comprising a first unit for transmitting incoming communications, a second unit for receiving incoming communications, a third unit for interfacing communications between the first and the second units, and a communications medium having a fluctuating transmission delay and connecting the first unit with the third unit, the method comprising the steps of:
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transmitting incoming communication traffic from the first unit at times dictated by first clock signals having a nominal frequency; conveying the communication traffic transmitted by the first unit via the communications medium to the third unit for reception; receiving the transmitted incoming communication traffic at the third unit; transmitting from the third unit to the second unit the incoming communication traffic received from the first unit at times dictated by clock signals having the nominal frequency and having a first phase that is offset by an adjustably fixed amount from a second phase; receiving incoming communication traffic transmitted from the third unit at the second unit at times dictated by clock signals having the nominal frequency and the second phase; determining whether the third unit receives incoming communication traffic from the first unit within predetermined windows of time prior to the times of transmission by the third unit of the received incoming communication traffic; and either increasing or decreasing the amount of the offset of the first phase from the second phase, in response to a determination that receptions of the incoming communication traffic at the third unit fall outside of the windows, to move the receptions into the windows. - View Dependent Claims (23, 24)
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25. A method of operating a communications system comprising a first unit for transmitting communications, a second unit for receiving outgoing communications, a third unit for interfacing communications between the first and the second units, and a communications medium having a fluctuating transmission delay and connecting the third unit with the second unit, the method comprising the steps of:
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transmitting outgoing communication traffic from the first unit at times dictated by clock signals having a nominal frequency and a first phase; receiving at the third unit the outgoing communication traffic transmitted by the first unit; transmitting from the third unit to the second unit outgoing communication traffic received from the first unit at times dictated by clock signals having the nominal frequency and having a second phase that is offset by an adjustably fixed amount from the first phase; conveying the communication traffic transmitted by the third unit via the communications medium to the second unit for reception; receiving at the second unit the outgoing communication traffic transmitted by the third unit; transmitting outgoing communication traffic from the second unit at times dictated by clock signals having the nominal frequency; determining whether the second unit receives outgoing communication traffic from the third unit within predetermined windows of time prior to the times of transmission by the second unit of the received outgoing communication traffic; and either increasing or decreasing the amount of the offset of the second phase from the first phase, in response to a determination that receptions of the outgoing communication traffic at the second unit fall outside of the windows, to move the receptions into the windows. - View Dependent Claims (26, 27)
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28. A method of operating a communications system comprising a first unit for transmitting outgoing communication traffic and receiving incoming communication traffic, a second unit for transmitting received incoming and outgoing communication traffic, a third unit for interfacing communications between the first and the second units, and a communications medium having a fluctuating transmission delay and connecting the second unit with the third unit, the method comprising the steps of:
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transmitting outgoing communication traffic from the first unit and receiving incoming communication traffic at the first unit at times dictated by first clock signals having a nominal frequency and a first phase; transmitting received incoming and outgoing communication traffic from the second unit at times dictated by second clock signals having the nominal frequency; receiving at the third unit the outgoing communication traffic transmitted by the first unit; transmitting from the third unit to the second unit outgoing communication traffic received from the first unit at times dictated by third clock signals having the nominal frequency and having a second phase that is offset by an adjustably fixed first amount from the first phase; conveying the outgoing communication traffic transmitted by the third unit via the communications medium to the second unit for reception; conveying the incoming communication traffic transmitted by the second unit via the communications medium to the third unit for reception; receiving at the third unit the incoming communication traffic transmitted by the second unit; transmitting from the third unit to the first unit incoming communication traffic received from the second unit at times dictated by fourth clock signals having the nominal frequency and having a third phase that is offset by an adjustably fixed second amount from the first phase; determining whether the second unit receives outgoing communication traffic from the third unit within first predetermined windows of time prior to the times of transmission by the second unit of the received outgoing communication traffic; determining whether the third unit receives incoming communication traffic from the second unit within second predetermined windows of time prior to the times of transmission by the third unit of the received incoming communication traffic; and either increasing or decreasing the amount of the offset of either the second phase or the third phase from the first phase, in response to a determination that either receptions of the outgoing communication traffic at the second unit fall outside of the first windows or receptions of the incoming communication traffic at the third unit fall outside of the second windows, to move the receptions that fall outside of their corresponding windows into the corresponding windows. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35)
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36. A method of processing call traffic in an interface arrangement of a cellular radio-telephone system that includes the arrangement, a communications medium connected to the apparatus and having a fluctuating transmission delay, at least one cell connected to the communications medium and each for transmitting first packets containing first frames of coded incoming call traffic received from a radio telephone to the arrangement across the medium and for transmitting to the radio telephone outgoing call traffic received across the medium from the arrangement in second packets containing second frames of coded outgoing call traffic, and a mobile-telephone switching system for interconnecting cells with each other and with a telephone network by routing a first digital stream of incoming call traffic received from the arrangement to a destination and by routing a second digital stream of outgoing call traffic received from a source to the arrangement and wherein the first and the second digital streams are synchronized with first clock signals having a nominal frequency and a first phase and derived from the telephone network, and the transmisions of the incoming and the outgoing call traffic by the cell are synchronized with second clock signals having the nominal frequency, the method comprising the steps of:
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receiving the second digital stream of outgoing call traffic synchronously with the first clock signals; coding the received outgoing call traffic; transmitting second frames of the coded outgoing call traffic synchronously with third clock signals having the nominal frequency and a second phase that is offset by an adjustably fixed first amount from the first phase; receiving the second frames of the coded outgoing call traffic; packetizing the received second frames into the second packets; transmitting the second packets to the cell via the communications medium synchronously with fifth clock signals having the nominal frequency and a fourth phase that is offset by an adjustably fixed third amount from the first phase; receiving the first packets from the cell via the communications medium; depacketizing the received first packets into the first frames; transmitting the first frames synchronously with sixth clock signals having the nominal frequency and a fifth phase that is offset by an adjustably fixed fourth amount from the first phase; receiving the first frames of the coded incoming call traffic synchronously with fourth clock signals having the nominal frequency and a third phase that is offset by an adjustably fixed second amount from the first phase; decoding the received incoming call traffic; transmitting the second digital stream of incoming call traffic synchronously with the first clock signals; determining whether the interface arrangement receives the first packets within first predetermined windows of time prior to the times of transmission of the first frames by the interface arrangement; determining whether the cell receives the second packets within second predetermined windows of time prior to the times of transmission by the cell of the received outgoing call traffic to the mobile telephone; and either increasing or decreasing the amounts of the offsets of either both the second and the fourth phases or both the third and the fifth phases, with respect to the first phase, in response to a determination that either receptions of the first packets fall outside of the first windows or receptions of the second packets fall outside of the second windows, to move the packet receptions that fall outside of their corresponding windows into the corresponding windows. - View Dependent Claims (37, 38, 39, 40, 41, 42)
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Specification