Mobile assisted handoff in radiocommunication systems
First Claim
1. A communications terminal comprising:
- means for receiving and processing a radio signal to produce a multichannel signal including a plurality of channels and to produce a demodulated signal corresponding to a single channel;
means for producing digital samples of said multichannel signal;
means for removing at least one channel from said digital samples of said multichannel signal, wherein processing means make energy measurements on said at least one channel, wherein said single channel and said at least one channel are associated with different frequencies.
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Abstract
Methods and apparatuses for radiocommunication systems including energy (e.g., signal strength) measurements are described. To enable measurements to be performed in parallel with information signal decoding and demodulation, a duplicate of a received signal can be made. The duplicate can be processed to enable measurement on any desired channel. Various access methodologies including FDMA, TDMA and CDMA are contemplated. The measurement information can then be reported to the system for usage in handoff determination. The inventive techniques allow for MAHO measurements to be performed without idle time being available for a receiver and without a dedicated scanning receiver being provided solely for measurement purposes.
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Citations
23 Claims
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1. A communications terminal comprising:
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means for receiving and processing a radio signal to produce a multichannel signal including a plurality of channels and to produce a demodulated signal corresponding to a single channel;
means for producing digital samples of said multichannel signal;
means for removing at least one channel from said digital samples of said multichannel signal, wherein processing means make energy measurements on said at least one channel, wherein said single channel and said at least one channel are associated with different frequencies. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
means for transmitting said measurements over an air interface.
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15. A method for making signal strength measurements on at least one channel comprising the steps of:
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generating a first and a second copy of a received signal;
processing said first copy to obtain an information signal on a first channel; and
processing said second copy to obtain signal strength measurements on said at least one channel, wherein said first channel and said at least one channel are associated with different frequencies. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
filtering said first copy to obtain a frequency band of interest; and
demodulating said first copy to obtain said information signal.
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17. The method of claim 15, wherein said step of processing said second copy further comprises the steps of:
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digitizing said second copy to produce digital samples;
buffering said digital samples; and
processing said buffered digital samples.
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18. The method of claim 17, wherein said step of processing said second copy further comprises the steps of:
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selecting from among said buffered digital samples, those samples associated with said at least one channel;
determining magnitude squared values of said selected digital samples; and
accumulating said magnitude squared values.
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19. The method of claim 17, wherein said step of processing said buffered digital samples further comprises the step of:
channelizing said buffered digital samples based upon at least one of frequency, time and spreading code.
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20. The method of claim 17, wherein said step of processing said buffered digital samples further comprises the step of:
processing said buffered digital samples using a fast fourier transform processor to separate said buffered digital samples by frequency.
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21. The method of claim 20, further comprising the step of:
extracting said at least one channel from said processed buffered digital samples based upon a desired time slot.
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22. The method of claim 20, further comprising the step of:
extracting said at least one channel from said processed buffered digital samples based upon a desired spreading code.
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23. A communication terminal comprising:
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a receiver for receiving a transmitted signal, processing said transmitted signal into a filtered signal and generating an information signal therefrom;
a splitter for generating a copy of said filtered signal; and
a processor for generating energy measurements on at least two channels associated with different frequencies using said copy of said filtered signal.
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Specification