Method and apparatus for overlaying two CDMA systems on the same frequency bandwidth
First Claim
1. A method of overlaying a second CDMA system over a first CDMA system comprising the steps of:
- transmitting a first signal using a first CDMA channelization;
transmitting a second signal using a second CDMA channelization, wherein said first and second CDMA channelization share at least a portion of a common frequency spectrum and wherein said first signal and said second signal are transmitted into a common coverage area;
obtaining signal energy corresponding to said first signal;
obtaining signal energy corresponding to said second signal;
comparing a phase of said first signal to a phase of said second signal to generate a phase error indication based upon said obtained signal energies; and
adjusting a phase at which said second signal is transmitted in response to said phase error indication.
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Abstract
In order to align the timing of an overlay base station to the timing of an existing base station, a sync unit is introduced into the system. The sync unit has a first receiver configured to receive a first signal, the first signal having a first CDMA channelization. The first receiver is configured to produce an indication of a timing of the first signal. The sync unit also has a second receiver configured to receive a second signal, the second signal having a second CDMA channelization. The second receiver is configured to produce an indication of a timing of the second signal. The sync unit also has a time error detection unit configured to compare the timing of the first signal and the timing of the second signal to determine a relative timing offset thereof.
13 Citations
25 Claims
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1. A method of overlaying a second CDMA system over a first CDMA system comprising the steps of:
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transmitting a first signal using a first CDMA channelization;
transmitting a second signal using a second CDMA channelization, wherein said first and second CDMA channelization share at least a portion of a common frequency spectrum and wherein said first signal and said second signal are transmitted into a common coverage area;
obtaining signal energy corresponding to said first signal;
obtaining signal energy corresponding to said second signal;
comparing a phase of said first signal to a phase of said second signal to generate a phase error indication based upon said obtained signal energies; and
adjusting a phase at which said second signal is transmitted in response to said phase error indication. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of overlaying a second CDMA system over a first CDMA system comprising the steps of:
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transmitting a first signal using a first CDMA channelization;
transmitting a second signal using a second CDMA channelization, wherein said first and second CDMA channelization share at least a portion of a common frequency spectrum and wherein said first signal and said second signal are transmitted into a common coverage area;
obtaining signal energy corresponding to said first signal;
obtaining signal energy corresponding to said second signal;
comparing a timing of said first signal to a timing of said second signal to generate a timing error indication based upon said obtained signal energies; and
adjusting a timing at which said second signal is transmitted in response to said timing error indication. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A CDMA system comprising:
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a first base station configured to transmit a first signal using a first CDMA channelization;
a second base station configured to transmit a second signal using a second CDMA channelization; and
a sync unit configured to receive said first signal and said second signal and configured to determine a relative phase difference therebetween;
wherein said second base station is further configured to adjust a phase at which said second signal is transmitted based upon said relative phase difference; and
wherein said first signal is transmitted using a first CDMA channelization and said second signal is transmitted using a second CDMA channelization. - View Dependent Claims (22, 23, 24)
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25. A CDMA system comprising:
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a first base station configured to transmit a first signal using a first CDMA channelization;
a second base station configured to transmit a second signal using a second CDMA channelization; and
a sync unit configured to receive said first signal and said second signal and configured to determine a relative timing difference therebetween;
wherein said second base station is further configured to adjust a timing at which said second signal is transmitted based upon said relative timing difference; and
wherein said first signal is transmitted using a first CDMA channelization and said second signal is transmitted using a second CDMA channelization.
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Specification