Efficient radio signal diversity combining using a small set of discrete amplitude and phase weights
First Claim
1. A method of diversity combining in a receiver, the method comprising:
- receiving a first received signal at a first antenna of the receiver;
receiving a second received signal at a second antenna of the receiver;
selecting an optimal complex weight A from a predetermined finite set of discrete complex weights, wherein the discrete complex weights comprise discrete gains and discrete phases, and wherein the finite set of discrete complex weights has less than 100 complex weights;
varying the amplitude and phase of the first received signal in accordance with the selected optimal weight A; and
combining the varied first received signal with the second received signal,wherein the optimal complex weight A is selected to maximize a signal-to-impairment ratio for the combined signal.
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Abstract
A method and apparatus for diversity-combining two electromagnetic signals (11,21) within a receiver (25). Two separated antennas (10,20) are employed. The antennas (10,20) are separated by some combination of spatial, polarization, and pattern separation. The first antenna (10) receives the first signal (11), and the second antenna (20) receives the second signal (21). Coupled to at least one of the antennas (10,20) is a circuit (12) for varying the gain and the phase of the signal (11,21) received at said antenna (10 or 20, respectively). The gain and the phase are constrained to be selected from within a finite set of preselected discrete gains and a finite set of preselected discrete phases. A search module (6) searches through all of the gain/phase combinations to optimize the signal-to-impairment ratio within the receiver (25). When the signal-to-impairment ratio is optimized, the gain and the phase are fixedly established. The search (6) is broken into two discrete searches, a relatively coarse search and a relatively fine search. The searching step (6) is typically performed whenever the signal-to-impairment ratio falls below a preselected value. A smart rounding module (14) can be used to recover the phase of the carrier of the combined signal (22) without any significant performance degradation.
50 Citations
20 Claims
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1. A method of diversity combining in a receiver, the method comprising:
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receiving a first received signal at a first antenna of the receiver; receiving a second received signal at a second antenna of the receiver; selecting an optimal complex weight A from a predetermined finite set of discrete complex weights, wherein the discrete complex weights comprise discrete gains and discrete phases, and wherein the finite set of discrete complex weights has less than 100 complex weights; varying the amplitude and phase of the first received signal in accordance with the selected optimal weight A; and combining the varied first received signal with the second received signal, wherein the optimal complex weight A is selected to maximize a signal-to-impairment ratio for the combined signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A diversity combining radio receiver device comprising:
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a first antenna coupled to a first received signal; a second antenna coupled to a second received signal; a signal varying circuit coupled to the first antenna, wherein the signal varying circuit varies the amplitude and phase of the first received signal in accordance with an optimal weight A selected from a predetermined finite set of discrete complex weights, wherein the discrete complex weights comprise discrete gains and discrete phases, and wherein the finite set of discrete complex weights has less than 100 complex weights; a signal combining circuit coupled to the signal varying circuit and the second antenna, wherein the signal combining circuit combines a varied first received signal produced by the signal varying circuit with the second received signal; wherein the optimal complex weight A maximizes a signal-to-impairment ratio for a combined signal produced by the signal combining circuit. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A method of diversity combining in a receiver, the method comprising:
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a) receiving a first received signal at a first antenna of the receiver; b) receiving a second received signal at a second antenna of the receiver; c) selecting a complex weight A from a predetermined finite set of discrete complex weights, wherein the discrete complex weights comprise various discrete gains and various discrete phases; d) combining the first received signal with the second received signal such that the first received signal is scaled in amplitude and phase relative to the second received signal in accordance with the selected complex weight A; e) calculating a signal-to-impairment ratio for the combined signal; f) repeating steps (c), (d), and (e) for a subset of distinct complex weights; and g) selecting an optimal weight from the subset of distinct complex weights, wherein the optimal weight corresponds to a maximum signal-to-impairment ratio. - View Dependent Claims (20)
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Specification