Cellular radio communications system
First Claim
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1. A cellular radio communication system for transmitting data over a plurality of transmission links comprising:
- a generator for producing a modulated signal by applying a modulation scheme to data to be transmitted across a transmission link;
an amplifier having a non-linear mode of amplification and a linear mode of amplification; and
a processor for determining the quality of said transmission link, wherein a constant envelope modulation scheme and said non-linear mode of amplification is used for transmitting said data when said quality determination falls below a threshold, and a second modulation scheme and said linear mode of amplification is used for transmitting said data when said quality determination exceeds said threshold.
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Abstract
A cellular radio communication system is provided for transmitting data over a plurality of transmission links. The system includes means for generating a modulated signal by applying a constant amplitude envelope modulation scheme to data to be transmitted across poor quality transmission links and amplifier means for non-linearly amplifying the modulated signal. The system can additionally include means for generating a second modulated signal by applying an amplitude dependent modulation scheme to data to be transmitted across higher quality transmission links and amplifier means for linearly amplifying the second modulated signal. Using a constant amplitude envelope modulation scheme, such as GMSK or MLCAM for poorer quality links means that for these links signals can be amplifier non-linearly at higher gains.
219 Citations
27 Claims
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1. A cellular radio communication system for transmitting data over a plurality of transmission links comprising:
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a generator for producing a modulated signal by applying a modulation scheme to data to be transmitted across a transmission link;
an amplifier having a non-linear mode of amplification and a linear mode of amplification; and
a processor for determining the quality of said transmission link, wherein a constant envelope modulation scheme and said non-linear mode of amplification is used for transmitting said data when said quality determination falls below a threshold, and a second modulation scheme and said linear mode of amplification is used for transmitting said data when said quality determination exceeds said threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A transmitting unit for a cellular radio communication system for transmitting data over at least one transmission link comprising:
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a generator for producing a modulated signal by applying a modulation scheme to data to be transmitted across a transmission link;
an amplifier having a non-linear mode of amplification and a linear mode of amplification; and
an input for receiving a quality determination for said link;
wherein a constant envelope modulation scheme and said non-linear mode of amplification is used for transmitting said data when said quality determination falls below a threshold, and a second modulation scheme and said linear mode of amplification is used for transmitting said data when said quality determination exceeds said threshold. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of operating a cellular radio communication system for transmitting data over a plurality of transmission links comprising the steps of:
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determining the quality of a transmission link;
selecting a modulation scheme and an amplification mode according to said determination;
generating a modulated signal by applying said modulation scheme to data to be transmitted across said transmission links; and
amplifying the modulated signal using said selected mode of an amplifier having a non-linear mode of amplification and a linear mode of amplification, wherein a constant envelope modulation scheme and said non-linear mode of amplification is selected when said quality determination falls below a threshold, and a second modulation scheme and said linear mode of amplification is selected when said quality determination exceeds said threshold. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
a Quadrature Phase Shift Keying (QPSK) modulation scheme, a 16-QAM (Quadrature Amplitude Modulation) modulation scheme and a 64-QAM (Quadrature Amplitude Modulation) modulation scheme depending on the quality determination.
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24. A method according to claim 20 additionally comprising the steps of:
applying a level of forward error correction coding when said quality determination exceeds said threshold.
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25. A method according to claim 20 additionally comprising the step of:
allocating each transmission link a default modulation scheme for use when a call is initiated, which default modulation scheme is the highest spectral efficiency modulation scheme which will deliver a predetermined bit error rate in poor environmental conditions.
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26. A method according to claim 20 wherein the transmission links comprise a point to multi-point link.
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27. A method according to claim 20 wherein the system is a wireless access system.
Specification
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Current AssigneeMicrosoft Technology Licensing LLC (Microsoft Corporation)
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Original AssigneeNortel Networks Limited (Nortel Networks Corporation)
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InventorsDaly, Neil
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Primary Examiner(s)Chin, Stephen
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Assistant Examiner(s)Pathak, Sudhanshu C.
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Application NumberUS09/599,277Time in Patent Office1,447 DaysField of Search370/337, 455/69, 375/259, 375/302, 375/261, 330/149US Class Current375/261CPC Class CodesH04L 1/0003 by switching between differ...H04L 2001/0096 Channel splitting in point-...H04L 27/2017 in which the phase changes ...H04L 27/34 Amplitude- and phase-modula...
