QPSK modulated backscatter system

Details QPSK modulated backscatter system QPSK modulated backscatter system

1996-12-31

2002-09-24

Trost, William G. (Department: 2683)

Pulse or digital communications

Systems using alternating or pulsating current

Angle modulation

C455S073000, C455S106000, C340S572100, C340S505000

Reexamination Certificate

active

06456668

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to wireless communication systems and, more particularly, to a wireless communication system using modulated backscatter technology.
2. Description of the Related Art
Radio Frequency IDentification (RFID) systems are used for identification and/or tracking of equipment, inventory, or living things. RFID systems are radio communication systems that communicate between a radio transceiver, called an Interrogator, and a number of inexpensive devices called Tags or transponders. In RFID systems, the Interrogator communicates to the Tags using modulated radio signals, and the Tags respond with modulated radio signals. The Interrogator first transmits an amplitude modulated signal to the Tag. Then, the Interrogator transmits a Continuous-Wave (CW) radio signal to the Tag. The Tag then modulates the CW signal using Modulated BackScattering (MBS) where the antenna is electrically switched, by the Tag's modulating signal, from being an absorber of RF radiation to being a reflector of RF radiation; thereby encoding the Tag's information onto the CW radio signal. The Interrogator demodulates the incoming modulated radio signal and decodes the Tag's information message.
MBS systems typically utilize amplitude modulated techniques for communications from the Interrogator to the Tag. For Tag to Interrogator MBS communications, prior art maintains the use of Frequency Shift Keying modulation techniques. Prior art also maintains baseband homodyne detection of the MBS signal at the interrogator; however baseband homodyne detection suffers from oscillator phase noise, large DC offsets, and mixer noise.
SUMMARY OF THE INVENTION
In an embodiment of this invention, we disclose techniques for utilizing Quadrature Phase Shift Keying (QPSK) in an MBS system; we also disclose techniques for extending QPSK to higher orders of phase modulation.
In accordance with an embodiment of the present invention, a duplex radio communication system comprises an Interrogator which generates a radio signal to at least one remote Tag. The remote Tag receives the radio signal. The Tag then generates a subcarrier signal, and using Quadrature Phase Shift Keying (QPSK), modulates an information signal onto the subcarrier. A Backscatter Modulator, using this modulated subcarrier, modulates the reflection of the radio signal, the reflected signal being a reflected modulated signal. The Interrogator receives and demodulates the reflected modulated signal to obtain the information signal. In one embodiment, demodulation utilizes a homodyne detector. In another embodiment, the Interrogator modulates an information signal onto the radio signal, transmits that modulated radio signal to the Tag, and the Tag demodulates that modulated radio signal to recover the information signal. In another embodiment, higher order phase modulations are used to modulate an information signal onto the subcarrier.


REFERENCES:
patent: 3720940 (1973-03-01), Fox et al.
patent: 3944928 (1976-03-01), Augenblick et al.
patent: 3984835 (1976-10-01), Kaplan et al.
patent: 4068232 (1978-01-01), Meyeres et al.
patent: 4075632 (1978-02-01), Baldwin et al.
patent: 4360810 (1982-11-01), Landt
patent: 4471345 (1984-09-01), Barrett, Jr.
patent: 4510495 (1985-04-01), Sigrimis et al.
patent: 4584534 (1986-04-01), Lijphart et al.
patent: 4641374 (1987-02-01), Oyama
patent: 4656463 (1987-04-01), Anders et al.
patent: 4691202 (1987-09-01), Denne et al.
patent: 4737789 (1988-04-01), Nysen
patent: 4739328 (1988-04-01), Koelle et al.
patent: 4816769 (1989-03-01), Ma et al.
patent: 4816839 (1989-03-01), Landt
patent: 4827395 (1989-05-01), Anders et al.
patent: 4888591 (1989-12-01), Landt et al.
patent: 4912471 (1990-03-01), Tyburski et al.
patent: 4937581 (1990-06-01), Baldwin et al.
patent: 4963887 (1990-10-01), Kawashima et al.
patent: 4993068 (1991-02-01), Piosenka et al.
patent: 5030807 (1991-07-01), Landt et al.
patent: 5039994 (1991-08-01), Wash et al.
patent: 5055659 (1991-10-01), Hendrick et al.
patent: 5086391 (1992-02-01), Chambers
patent: 5131038 (1992-07-01), Puhl et al.
patent: 5153919 (1992-10-01), Reeds
patent: 5164985 (1992-11-01), Nysen et al.
patent: 5214409 (1993-05-01), Beigel
patent: 5214410 (1993-05-01), Verster
patent: 5227803 (1993-07-01), O'Connor et al.
patent: 5251218 (1993-10-01), Stone et al.
patent: 5252979 (1993-10-01), Nysen
patent: 5264854 (1993-11-01), Spiess
patent: 5305008 (1994-04-01), Turner et al.
patent: 5305459 (1994-04-01), Rydel
patent: 5339073 (1994-08-01), Dodd et al.
patent: 5347263 (1994-09-01), Carroll et al.
patent: 5353301 (1994-10-01), Mitzlaff
patent: 5381137 (1995-01-01), Ghaem et al.
patent: 5390339 (1995-02-01), Bruckert et al.
patent: 5400949 (1995-03-01), Hirvonen et al.
patent: 5410315 (1995-04-01), Huber
patent: 5420757 (1995-05-01), Eberhardt et al.
patent: 5423056 (1995-06-01), Linquist et al.
patent: 5425032 (1995-06-01), Shloss et al.
patent: 5426667 (1995-06-01), van Zon
patent: 5434572 (1995-07-01), Smith
patent: 5438329 (1995-08-01), Gastouniotis et al.
patent: 5448110 (1995-09-01), Tuttle et al.
patent: 5448242 (1995-09-01), Sharpe et al.
patent: 5455575 (1995-10-01), Schuermann
patent: 5461385 (1995-10-01), Armstrong
patent: 5463402 (1995-10-01), Walrath et al.
patent: 5477215 (1995-12-01), Mandelbaum
patent: 5478991 (1995-12-01), Watanabe et al.
patent: 5479160 (1995-12-01), Koelle
patent: 5479416 (1995-12-01), Snodgrass et al.
patent: 5485520 (1996-01-01), Chaum et al.
patent: 5491484 (1996-02-01), Schuermann
patent: 5510795 (1996-04-01), Koelle
patent: 5521944 (1996-05-01), Hegeler et al.
patent: 5523749 (1996-06-01), Cole et al.
patent: 5525993 (1996-06-01), Pobanz et al.
patent: 5525994 (1996-06-01), Hurta et al.
patent: 5530202 (1996-06-01), Dais et al.
patent: 5543798 (1996-08-01), Schuermann
patent: 5559828 (1996-09-01), Armstrong et al.
patent: 5565858 (1996-10-01), Guthrie
patent: 5572222 (1996-11-01), Mailandt et al.
patent: 5581576 (1996-12-01), Lanzetta et al.
patent: 5600538 (1997-02-01), Xanthopoulos
patent: 5610939 (1997-03-01), Takahashi et al.
patent: 5633613 (1997-05-01), MacDonald
patent: 5640683 (1997-06-01), Evans et al.
patent: 5649295 (1997-07-01), Shober et al.
patent: 5649296 (1997-07-01), Maclellan et al.
patent: 5686928 (1997-11-01), Pritchett et al.
patent: 5708444 (1998-01-01), Pouwels et al.
patent: 5727027 (1998-03-01), Tsuda
patent: 5760653 (1998-06-01), Soda
patent: 5774673 (1998-06-01), Beuk et al.
patent: 5774876 (1998-06-01), Woolley et al.
patent: 5796827 (1998-08-01), Coppersmith et al.
patent: 5804810 (1998-09-01), Wolley et al.
patent: 5850187 (1998-12-01), Carrender et al.
patent: 5852403 (1998-12-01), Boardman
patent: 5872516 (1999-02-01), Bonge, Jr. et al.
patent: 5873025 (1999-02-01), Evans et al.
patent: 5874903 (1999-02-01), Shuey et al.
patent: 5929779 (1999-07-01), MacLellan et al.
patent: 5940006 (1999-08-01), MacLellan et al.
patent: 5943378 (1999-08-01), Keba et al.
patent: 5952922 (1999-09-01), Shober
patent: 6023610 (2000-02-01), Wood et al.
patent: 0 313 491 (1989-04-01), None
patent: 0 346 922 (1989-12-01), None
patent: 0 520 445 (1992-12-01), None
patent: 0 670 558 (1995-02-01), None
patent: 0 724 351 (1996-07-01), None
patent: 0 732 597 (1996-09-01), None
patent: 0 750 200 (1996-12-01), None
patent: 0 750 201 (1996-12-01), None
patent: 0779 520 (1996-12-01), None
patent: 1 098 431 (1982-11-01), None
patent: 2 193 359 (1988-02-01), None
patent: 2 202 415 (1988-09-01), None
patent: S63-52082 (1988-03-01), None
patent: WO 89/05549 (1989-06-01), None
patent: WO 94/19781 (1994-09-01), None
“A Microwave Noncontact Identification Transponder Using Subharmonic Interrogation,” Carol W. Pobanz, 8099 IEEE Transactions on Microwave Theroy and Techniques, 43 (1995), Jul., No. 7, PT. II, New York, US, pp. 1673-1679.
“A Coded Radar Reflector For Remote Identification Of Personnel And Vehicles,” Frank R. Williamson, Lacey F. Moore, Ralph Brooks, Julie Anne Williamson, and Melvin C. McGee, Record of the 1993 IEEE National Radar Conference, Lynnfield, MA, USA, Apr.

Affiliated with

Also associated with

Rating

QPSK modulated backscatter system does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with QPSK modulated backscatter system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and QPSK modulated backscatter system will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2831441