`US009014243B2
`
`(12) United States Patent
`Tzannes
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`US 9,014,243 B2
`Apr. 21, 2015
`
`(54) SYSTEM AND METHOD FOR SCRAMBLING
`USING A BIT SCRAMBLER AND A PHASE
`SCRAMBLER
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`(71) Applicant: TQ Delta, LLC, Austin, TX (US)
`
`(72)
`
`Inventor: Marcos C. Tzannes, Orinda, CA (US)
`
`(73) Assiguee: TQ Delta, LLC, Austin, "X (US)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`EP
`EP
`
`3,898,566 A
`3,955,141 A
`4,069,392 A
`
`8/1975 Switzer et al.
`5/1976 Lyon et al.
`1/1978 Goldcnberg et al.
`(Continued)
`FOREIGN PATENT DOCUMENTS
`0584534
`3/1994
`0719004
`6/1996
`
`(Continued)
`OTHER PUBLICATIONS
`
`(21) App]. No.: 13/718,016
`
`(22)
`
`Filed:
`
`Dec. 18, 2012
`
`(65)
`
`Prior Publication Data
`US 2013/0136160 Al
`May 30,2013
`
`Related U.S. Application Data
`(60) Continuation of application No. 13/439,605, filed on
`Apr. 4, 2012, now Pat. No. 8,355,427, which is a
`continuation of application No. 13/284,549, filed on
`Oct. 28, 2011, now Pat. No. 8,218,610, which is a
`
`(Continued)
`
`(51)
`
`(2006.01)
`(2006.01)
`(2006.01)
`
`Int. Cl.
`H041, 2706
`H04L 25/03
`H0413 1/40
`'
`(52) U.S. Cl.
`CPC .... .. H04L 2 7/262 7 (2013.01); H04L 25/03866
`(2013.01); H04L 27/2614 (2013.01); H04L
`27/2621 (201301); H04B 1/40 (2013.01)
`(58) Field of Classification Search
`USPC ........................................1. 375/222, 340, 341
`See application file for complete Search history.
`
`Baum] et 31., “Reducing the Peak-To—Average Power Ratio of
`Multicarrier Modulation by Selected Mapping,” Electronics Letters,
`GB, IEE Stevenage, vol. 32(22), Oct. 24, 1996, pp. 2056-2057,
`XP000643915 ISSN: 0013-5194.
`(Continued)
`
`. Primary Examiner — Jaison Joseph
`(74) Attorney, Agent, or Firm —Jason I-I. Vick; Sheridan
`Ross, PC
`
`ABSTRACT
`(57)
`A system and method that demodulates the phase character-
`istic of a carrier signal are described. The scrambling of the
`phase characteristic of each carrier signal includes associat-
`ing a value with each carrier signal and computing a phase
`shift for each carrier signal based on the value associated with
`that carrier signal. The Value is determined independently of
`any input bit value carried by that carrier signal. The phase
`shift computed for each carrier signal is combined with the
`phase characteristic ofthat carrier signal so as to substantially
`scramble the phase characteristic ofthe carrier signals. Bits of
`an input ‘signal are modulated onto the carrier signals having
`the substantially scrambled phase characteristic to produce a
`transmission signal with a reduced PAR.
`
`25 Claims, 2 Drawing Sheets
`
`
`
`Receiver
`Phase
`Dsscramblar
`
`Transmitter
`
`Remote _
`Transceiver
`.13.
`
`1QAM
`Encoder
`5.2
`
`Transceiver 1|!
`
`CIOMCAST-1001
`
`Comcast Cable Communications LLC, et. al. v. T0 Delta
`
`Page 1 of 12
`
`
`
`US 9,014,243 B2
`Page 2
`
`Related U.S. Application Data
`
`continuation of application No. 11/860,080, filed on
`Sep. 24, 2007, now Pat. No. 8,073,041, which is a
`division of application No. 11/211,535, filed on Aug.
`26, 2005, now Pat. No. 7,292,627, which is a continu(cid:173)
`ation of application No. 09/710,310, filed on Nov. 9,
`2000, now Pat. No. 6,961,369.
`
`(60) Provisional application No. 60/164,134, filed on Nov.
`9, 1999.
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`1111982 Qureshi
`4,358,853 A
`4,985,900 A
`111991 Rhindetal.
`111995 Jasper et al.
`5,381,449 A
`10/1997 Hayashino et al.
`5,682,376 A
`12/1997 Myer et al.
`5,694,395 A
`5,742,679 A * 4/1998 Olafsson ....................... 370/527
`5,748,677 A
`5/1998 Kumar
`5,870,016 A
`2/1999 Shrestha
`5,896,419 A * 4/1999 Suzuki .......................... 375/219
`5,903,614 A * 5/1999 Suzuki et al. ................. 375/340
`5,914,932 A * 6/1999 Suzuki et al. ................. 370/203
`5,937,010 A
`8/1999 Petranovich et al.
`5,991,262 A
`1111999 Laird et al.
`6,128,350 A
`10/2000 Shastri et al.
`6,256,355 Bl
`7/2001 Sakoda et al.
`6,259,685 Bl
`7/2001 Rinne et al.
`6,366,555 Bl
`412002 Gatherer et al.
`6,507,585 Bl
`112003 Dobson
`6,519,292 Bl
`212003 Sakoda et al.
`6,590,860 Bl * 7/2003 Sakoda et al.
`6,704,317 Bl
`3/2004 Dobson
`6,757,299 Bl
`6/2004 Verma
`6,781,951 Bl
`8/2004 Fifield
`6,961,369 Bl
`1112005 Tzannes
`6,967,997 B2
`1112005 Humphrey
`7,257,168 B2
`8/2007 Goldstein et al.
`7,286,614 B2
`10/2007 Goldstein et al.
`7,292,627 B2
`1112007 Tzannes
`7,471,721 B2
`12/2008 Tzannes
`10/2009 Cimini, Jr. et al.
`7,610,028 B2
`7,769,104 B2
`8/2010 Tzannes
`8,073,041 Bl
`12/2011 Tzannes
`112012 Tzannes
`8,090,008 B2
`8,218,610 B2
`7/2012 Tzannes
`2002/0172146 Al
`1112002 Wu eta!.
`2003/0128673 Al
`7/2003 Lee et al.
`2005/0141410 Al
`6/2005 Zhang et al.
`200610092902 Al
`512006 Schmidt
`200610140288 Al
`612006 Holden
`2010/0190507 Al
`7/2010 Karabinis et al.
`2012/0069878 Al
`3/2012 Tzannes
`2012/0195353 Al
`8/2012 Tzannes
`
`................ 370/203
`
`FOREIGN PATENT DOCUMENTS
`
`EP
`GB
`JP
`JP
`WO
`WO
`WO
`
`1542488
`2330491
`H08(1996)-321820
`H10(1998)-084329
`WO 98/32065
`WO 99/22463
`WO 99/29078
`
`6/2005
`4/1999
`12/1996
`3/1998
`7 /1998
`5/1999
`6/1999
`
`OTHER PUBLICATIONS
`
`Henkel, "Analog Codes for Peak-to-Average Ratio Reduction," in
`Proceedings 3rd ITG Conf. Source and Channel Coding, Munich,
`Germany, Jan. 2000, 5 pages.
`Narahashi et al., "New phasing scheme of N multiple carriers for
`reducing peak-to-average power ratio," Electronics Letters, Aug.
`1994, vol. 30(17), pp. 1382-1383.
`
`Tellado et al., "Revisiting DMT's Peak-to-Average Ratio," Antwerp,
`Apr. 20-24, 1998, pp. 1-14.
`Tellambura, "A coding technique for reducing peak-to-average
`power ratio in OFDM," In the Proceedings of Global Telecommuni(cid:173)
`cations Conference, IEEE, Nov. 1998, pp. 2783-2787.
`Tellambura, "Phase optimisation criterion for reducing peak-to-av(cid:173)
`erage power ratio in OFDM," Electronics Letters, Jan. 1998, vol.
`34(2), pp. 169-170.
`Van Eetvelt et al., "Peak to average power reduction for OFDM
`schemes by selective scrambling," Electronics Letters, Oct. 1996,
`vol. 32(21), pp. 1963-1964.
`Invitation to Pay Additional Fees for International (PCT) Patent
`Application No. PCT/US00/30958, mailed Mar. 23, 2001.
`Invitation to Restrict or to Pay Additional Fees for International
`(PCT) Patent Application No. PCT/US00/30958, mailed Nov. 14,
`2001.
`Annex to Form PCT/ISA/206 for PCT/US00/30958, Mar. 23, 2001,
`3 pages.
`International Search Report for International (PCT) Patent Applica(cid:173)
`tion No. PCT/US00/30958, mailed Jun. 12, 2001.
`International Preliminary Examination Report for International
`(PCT) Patent Application No. PCT/US00/30958, completed Mar. 4,
`2002.
`Written Opinion for International (PCT) Patent Application No.
`PCT/US00/30958, mailed Dec. 18, 2001.
`Notification of Reasons for Refusal (including translation) for Japa(cid:173)
`nese Patent Application No. 2001-537217, date of dispatch, Mar. 3,
`2008.
`Decision of Refusal (including translation) for Japanese Patent
`Application No. 2001-537217, date of dispatch, Nov. 4, 2008.
`Notice of Preliminary Rejection (translation only) for Korean Patent
`Application No. 7005830/2002 dated Nov. 22, 2006.
`Official Action for U.S. Appl. No. 09/710,310, mailed May4, 2004.
`Notice of Allowance for U.S. Appl. No. 09/710,310, mailed Jul. 5,
`2005.
`Notice of Allowance for U.S. Appl. No. 111211,535, mailed Sep. 6,
`2007.
`Notice of Allowance for U.S. Appl. No. 111860,080, mailed Oct. 17,
`2011.
`Notice of Allowance for U.S. Appl. No. 13/284,549, mailed Mar. 20,
`2012.
`Notice of Allowance for U.S. Appl. No. 13/439,605, mailed Sep. 14,
`2012.
`Official Action for U.S. Appl. No. 111863,581, mailed Feb. 6, 2008.
`Notice of Allowance for U.S. Appl. No. 111863,581, mailed Oct. 8,
`2008.
`Official Action for U.S. Appl. No. 12/255,713, mailed Oct. 15, 2009.
`Notice of Allowance for U.S. Appl. No. 12/255,713, mailed May 18,
`2010.
`Notice of Allowance for U.S. Appl. No. 12/783,725, mailed Nov. 17,
`2011.
`Official Action for U.S. Appl. No. 13/303,417, mailed Jul. 5, 2013.
`Notice of Allowance for U.S. Appl. No. 13/303,417, mailed Feb. 7,
`2014.
`U.S. Appl. No. 14/256,677, filed Apr. 18, 2014, Tzannes.
`Official Action for U.S. Appl. No. 14/256,677 mailed Sep. 18, 2014.
`Notice of Allowance for U.S. Appl. No. 14/256,677 mailed Nov. 17,
`2014.
`Petition for Inter Partes Review of Claims 20 and 26 of U.S. Patent
`No. 7,292,627 Under 35 U.S.C. §§ 311-319 and 37 C.F.R. § 42,
`including Exhibits 1001-1022, Case No, IPR2015-00247, filed Nov.
`7, 2014 (786 pages).
`Petition for Inter Partes Review of Claim 1 of U.S. Patent No.
`7,471,721Under35 U.S.C. §§ 311-319 and37 C.F.R. § 42, including
`Exhibits 1001-1022, Case No. IPR2015-00239, filed Nov. 7, 2014,
`(775 pages).
`PetitionforinterPartes Review of Claims 1and14 ofU.S. Patent No.
`8,090,008 Under 35 U.S.C. §§ 311-319 and37 C.F.R. § 42, including
`Exhibits 1001-1021, Case No. IPR2015-00240, filed Nov. 7, 2014,
`(830 pages).
`
`Page 2 of 12
`
`
`
`US 9,014,243 B2
`Page 3
`
`(56)
`
`References Cited
`
`OTHER PUBLICATIONS
`
`PetitionforinterPartes Review of Claims 1and14 ofU.S. Patent No.
`8,073,041Under35 U.S.C. §§ 311-319 and37 C.F.R. § 42, including
`Exhibits 1001-1022, Case No. IPR2015-00241, filed Nov. 7, 2014
`(815 pages).
`U.S. Appl. No. 14/540,332, filed Nov. 13, 2014, Tzannes.
`Petition for Inter Partes Review of Claims 1, 6, 7, and 31 of U.S.
`Patent No. 8,218,610 Under 35 U.S.C. §§ 311-319 and 37 C.F.R. §
`42, including Exhibits 1001-1021, Case No. IPR2015-00242, filed
`Nov. 7, 2014 (882 pages).
`Petition for Inter Partes Review of Claims 1, 6, 7, and 29 of U.S.
`Patent No. 8,355,427 Under 35 U.S.C. §§ 311-319 and 37 C.F.R. §
`42, including Exhibits 1001-1022, Case No. IPR2015-00243, filed
`Nov. 7, 2014 (909 pages).
`TQ Delta LLC's Mandatory Notices Under 37 C.F.R. 42.8(a)(2) for
`2Wire, Inc. v. TQ Delta, LLC, United States Patent and Trademark
`Office-Before the Patent Trial and Appeal Board, Case No. IPR
`2015-00247 filed Nov. 26, 2014 (5 pages).
`Notice of Filing Date Accorded to Petition and Time for Filing Patent
`Owner Preliminary Response for 2Wire, Inc. v. TQ Delta, LLC,
`United States Patent and Trademark Office-Before the Patent Trial
`and Appeal Board, Case No. IPR 2015-00247 filed Dec. 1, 2014 (4
`pages).
`Order-Authorization to File a Motion to Correct Filing Date 37
`C.F.R. § 42.5 for 2Wire, Inc. v. TQ Delta, LLC, United States Patent
`and Trademark Office-Before the Patent Trial and Appeal Board,
`Case No. IPR 2015-00247 filed Dec. 5, 2014 (3 pages).
`2Wire, Inc.'s Motion to Correct Filing Date (Including Exhibits
`1023-1030) for 2Wire, Inc. v. TQ Delta, LLC, United States Patent
`and Trademark Office-Before the Patent Trial and Appeal Board,
`Case No. IPR 2015-00247 filed Dec. 12, 2014 (57 pages).
`TQ Delta LLC's Opposition to Petitioner's Motion to Change the
`Petition Filing Date for 2Wire, Inc. v. TQ Delta, LLC, United States
`Patent and Trademark Office-Before the Patent Trial and Appeal
`Board, Case No. IPR 2015-00247 filed Dec. 19, 2014 (7 pages).
`Decision-Motion to Correct Filing Date 37 C.F.R § 42.5 for 2Wire,
`Inc. v. TQ Delta, LLC, United States Patent and Trademark Office(cid:173)
`Before the Patent Trial and Appeal Board, Case No. IPR2015-00247
`filed Jan. 15, 2015 (9 pages).
`TQ Delta LLC's Mandatory Notices Under 37 C.F.R. 42.8(a)(2) for
`2Wire, Inc. v. TQ Delta, LLC, United States Patent and Trademark
`Office-Before the Patent Trial and Appeal Board, Case No. IPR
`2015-00239 filed Nov. 26, 2014 (5 pages).
`Notice of Filing Date Accorded to Petition and Time for Filing Patent
`Owner Preliminary Response for 2Wire, Inc. v. TQ Delta, LLC,
`United States Patent and Trademark Office-Before the Patent Trial
`and Appeal Board, Case No. IPR 2015-00239 filed Dec. 1, 2014 (4
`pages).
`Order-Authorization to File a Motion to Correct Filing Date 37
`C.F.R. § 42.5 for 2Wire, Inc. v. TQ Delta, LLC, United States Patent
`and Trademark Office-Before the Patent Trial and Appeal Board,
`Case No. IPR 2015-00239 filed Dec. 5 2014 (3 pages).
`2Wire, Inc.'s Motion to Correct Filing Date (Including Exhibits
`1023-1030) for 2Wire, Inc. v. TQ Delta, LLC, United States Patent
`and Trademark Office-Before the Patent Trial and Appeal Board,
`Case No. IPR 2015-00239 filed Dec. 12, 2014 (57 pages).
`TQ Delta LLC's Opposition to Petitioner's Motion to Change the
`Petition Filing Date for 2Wire, Inc. v. TQ Delta, LLC, United States
`Patent and Trademark Office-Before the Patent Trial and Appeal
`Board, Case No. IPR 2015-00239 filed Dec. 19, 2014 (7 pages).
`Decision-Motion to Correct Filing Date 37 C.F.R § 42.5 for 2Wire,
`Inc. v. TQ Delta, LLC, United States Patent and Trademark Office(cid:173)
`Before the Patent Trial and Appeal Board, Case No. IPR 2015-00239
`filed Jan. 15, 2015 (9 pages).
`TQ Delta LLC's Mandatory Notices Under 37 C.F.R 42.8(a)(2) for
`2Wire, Inc. v. TQ Delta, LLC, United States Patent and Trademark
`Office-Before the Patent Trial and Appeal Board, Case No. IPR
`2015-00240 filed Nov. 26, 2014 (5 pages).
`Notice of Filing Date Accorded to Petition and Time for Filing Patent
`Owner Preliminary Response for 2Wire, Inc. v. TQ Delta, LLC,
`
`United States Patent and Trademark Office-Before the Patent Trial
`and Appeal Board, Case No. IPR 2015-00240 filed Dec. 1, 2014 (4
`pages).
`Order: Authorization to File a Motion to Correct Filing Date 37
`C.F.R. § 42.5 for 2Wire, Inc. v. TQ Delta, LLC, United States Patent
`and Trademark Office-Before the Patent Trial and Appeal Board,
`Case No. IPR 2015-00240 filed Dec. 5, 2014 (3 pages).
`2Wire, Inc.'s Motion to Correct Filing Date for 2Wire, Inc. v. TQ
`Delta, LLC, United States Patent and Trademark Office-Before the
`Patent Trial and Appeal Board, Case No. IPR 2015-00240 filed Dec.
`12, 2014 (57 pages).
`TQ Delta LLC's Opposition to Petitioner's Motion to Change the
`Petition Filing Date for 2Wire, Inc. v. TQ Delta, LLC, United States
`Patent and Trademark Office-Before the Patent Trial and Appeal
`Board, Case No. IPR 2015-00240 filed Dec. 19, 2014 (7 pages).
`Decision: Motion to Correct Filing Date 37 C.F.R. § 42.5 for 2Wire,
`Inc. v. TQ Delta, LLC, United States Patent and Trademark Office(cid:173)
`Before the Patent Trial and Appeal Board, Case No. IPR 2015-00240
`filed Jan. 15, 2015 (9 pages).
`TQ Delta LLC's Mandatory Notices Under 37 C.F.R. 42.8(a)(2) for
`2Wire, Inc, v. TQ Delta, LLC, United States Patent and Trademark
`Office-Before the Patent Trial and Appeal Board, Case No. IPR
`2015-00241 filed Nov. 26, 2014 (5 pages).
`Notice of Filing Date Accorded to Petition and Time for Filing Patent
`Owner Preliminary Response for 2Wire, Inc. v. TQ Delta, LLC,
`United States Patent and Trademark Office6-Before the Patent Trial
`and Appeal Board, Case No. IPR 2015-00241 filed Dec. 1, 2014 (4
`pages).
`Order: Authorization to File a Motion to Correct Filing Date 37
`C.F.R. § 42.5 for 2Wire, Inc. v. TQ Delta, LLC, United States Patent
`and Trademark Office-Before the Patent Trial and Appeal Board,
`Case No. IPR 2015-00241 filed Dec. 5, 2014 (3 pages).
`2Wire, Inc.'s Motion to Correct Filing Date for 2Wire, Inc. v. TQ
`Delta, LLC, United States Patent and Trademark Office-Before the
`Patent Trial and Appeal Board, Case No. IPR 2015-00241 filed Dec.
`12, 2014 (57 pages).
`TQ Delta LLC's Opposition to Petitioner's Motion to Change the
`Petition Filing Date for 2Wire, Inc. v. TQ Delta, LLC, United States
`Patent and Trademark Office-Before the Patent Trial and Appeal
`Board, Case No. IPR 2015-00241 filed Dec. 19, 2014 (7 pages).
`Decision: Motion to Correct Filing Date 37 C.F.R. § 42.5 for 2Wire,
`Inc. v. TQ Delta, LLC, United States Patent and Trademark Office(cid:173)
`Before the Patent Trial and Appeal Board, Case No. IPR2015-00241
`filed Jan. 15, 2015 (9 pages).
`TQ Delta LLC's Mandatory Notices Under 37 C.F.R. 42.8(a)(2) for
`2Wire, Inc. v. TQ Delta, LLC, United States Patent and Trademark
`Office-Before the Patent Trial and Appeal Board, Case No. IPR
`2015-00242 filed Nov. 26, 2014 (5 pages).
`Notice of Filing Date Accorded to Petition and Time for Filing Patent
`Owner Preliminary Response for 2Wire, Inc. v. TQ Delta, LLC,
`United States Patent and Trademark Office-Before the Patent Trial
`and Appeal Board, Case No. IPR 2015-00242 filed Dec. 1, 2014 (4
`pages).
`Order: Authorization to File a Motion to Correct Filing Date 37
`C.F.R. § 42.5 for 2Wire, Inc. v. TQ Delta, LLC, United States Patent
`and Trademark Office-Before the Patent Trial and Appeal Board,
`Case No. IPR 2015-00242 filed Dec. 5, 2014 (3 pages).
`2Wire, Inc.'s Motion to Correct Filing Date for 2Wire, Inc. v. TQ
`Delta, LLC, United States Patent and Trademark Office-Before the
`Patent Trial and Appeal Board, Case No. IPR 2015-00242 filed Dec.
`12, 2014 (57 pp.).
`TQ Delta LLC's Opposition to Petitioner's Motion to Change the
`Petition Filing Date for 2Wire, Inc. v. TQ Delta, LLC, United States
`Patent and Trademark Office-Before the Patent Trial and Appeal
`Board, Case No. IPR 2015-00242 filed Dec. 19, 2014 (7 pages).
`Decision: Motion to Correct Filing Date 37 C.F.R. § 42.5 for 2Wire,
`Inc. v. TQ Delta, LLC, United States Patent and Trademark Office(cid:173)
`Before the Patent Trial and Appeal Board, Case No. IPR2015-00242
`filed Jan. 15, 2015 (9 pages).
`TQ Delta LLC's Mandatory Notices Under 37 C.F.R. 42.8(a)(2) for
`2Wire, Inc. v. TQ Delta, LLC, United States Patent and Trademark
`Office-Before the Patent Trial and Appeal Board, Case No. IPR
`2015-00243 filed Nov. 26, 2014 (5 pages).
`
`Page 3 of 12
`
`
`
`US 9,014,243 B2
`Page 4
`
`(56)
`
`References Cited
`
`OTHER PUBLICATIONS
`
`Notice of Filing Date Accorded to Petition and Time for Filing Patent
`Owner Preliminary Response for 2Wire, Inc. v. TQ Delta, LLC,
`United States Patent and Trademark Office-Before the Patent Trial
`and Appeal Board, Case No. IPR 2015-00243 filed Dec. 1, 2014 (4
`pages).
`Order: Authorization to File a Motion to Correct Filing Date 37
`C.F.R. § 42.5 for 2Wire, Inc. v. TQ Delta, LLC, United States Patent
`and Trademark Office-Before the Patent Trial and Appeal Board,
`Case No. IPR 2015-00243 filed Dec. 5, 2014 (3 pages).
`
`2Wire, Inc.'s Motion to Correct Filing Date for 2Wire, Inc. v. TQ
`Delta, LLC, United States Patent and Trademark Office-Before the
`Patent Trial and Appeal Board, Case No. IPR 2015-00243 filed Dec.
`12, 2014 (57 pages).
`TQ Delta LLC's Opposition to Petitioner's Motion to Change the
`Petition Filing Date for 2Wire, Inc. v. TQ Delta, LLC, United States
`Patent and Trademark Office-Before the Patent Trial and Appeal
`Board, Case No. IPR 2015-00243 filed Dec. 19, 2014 (7 pages).
`Decision: Motion to Correct Filing Date 37 C.F.R. § 42.5 for 2Wire,
`Inc. v. TQ Delta, LLC, United States Patent and Trademark Office(cid:173)
`Before the Patent Trial and Appeal Board, Case No. IPR2015-00243
`filed Jan. 15, 2015 (9 pages).
`* cited by examiner
`
`Page 4 of 12
`
`
`
`76
`
`74
`
`I
`.: Scrambler f
`~-----------J
`
`54
`
`22
`
`26
`
`Receiver
`
`Transceiver 1.Q
`
`18
`
`FIG. 1
`
`2
`
`34
`
`~
`00
`•
`~
`~
`~
`
`~ = ~
`
`Receiver
`
`I I
`
`66'
`
`I I
`
`30
`
`l /l
`
`Phase
`Descrambler
`
`Transmitter
`
`Remote
`Transceiver
`H.
`
`>
`'e :-:
`N .... ~
`0 ....
`
`N
`
`Ul
`
`('D
`
`1J1 =-('D
`.....
`....
`0 .....
`N
`
`d
`rJl
`
`'N
`
`\C = "'"" ~
`~ w = N
`
`Page 5 of 12
`
`
`
`U.S. Patent
`
`Apr. 21, 2015
`
`Sheet 2of2
`
`US 9,014,243 B2
`
`STEP 100
`
`GENERATE VALUE(S)
`
`,------------ ------------
`STEP 110-1
`COMMUNICATE VALUE(S)
`:
`TO SYNCHRONIZE
`:
`1
`~------------ -----------~
`
`STEP 115
`
`COMPUTE PHASE SHIFT
`
`STEP 120
`
`COMBINE PHASE SHIFT WITH
`PHASE CHARACTERISTIC
`
`-----,
`
`STEP 130
`
`COMBINE CARRIER SIGNALS INTO
`A TRANSMISSION SIGNAL
`
`,,, ......
`
`,,/'
`
`............
`......
`
`......
`
`/
`
`/
`
`/
`
`'
`r-----------,
`'-....
`,,,"'
`,,,,,,"' DETECT CLIPPING "'<YES I
`TRANSMIT
`1
`STEP 140-<, OF TRANSMISSION ,,,/--~ PREDEFINED l
`L ___ ~l§~~_!:. ___ J
`",,
`SIGNAL
`,,,,,,"'
`'-....
`?
`,,-"'
`'STEP
`.....
`150
`
`..........
`'
`
`.....
`
`/
`
`/
`
`//
`
`STEP 160
`
`TRANSMIT TRANSMISSION SIGNAL
`
`FIG. 2
`
`Page 6 of 12
`
`
`
`US 9,014,243 B2
`
`1
`SYSTEM AND METHOD FOR SCRAMBLING
`USING A BIT SCRAMBLER AND A PHASE
`SCRAMBLER
`
`RELATED APPLICATION
`
`2
`voltage, current, phase, frequency, power) to the time-aver(cid:173)
`aged value of the signal parameter. In DMT systems, the PAR
`of the transmitted signal is determined by the probability of
`the random transmission signal reaching a certain peak volt(cid:173)
`age during the time interval required for a certain number of
`symbols. An example of the PAR of a transmission signal
`transmitted from a DMT transmitter is 14.5 dB, which is
`equivalent to having a lE-7 probability of clipping. The PAR
`of a transmission signal transmitted and received in a DMT
`10 communication system is an important consideration in the
`design of the DMT communication system because the PAR
`of a signal affects the communication system's total power
`consumption and component linearity requirements of the
`system.
`If the phase of the modulated carriers is not random, then
`the PAR can increase greatly. Examples of cases where the
`phases of the modulated carrier signals are not random are
`when bit scramblers are not used, multiple carrier signals are
`used to modulate the same input data bits, and the constella-
`20 ti on maps, which are mappings of input data bits to the phase
`of a carrier signal, used for modulation are not random
`enough (i.e., a zero value for a data bit corresponds to a 90
`degree phase characteristic of the DMT carrier signal and a
`one value for a data bit corresponds to a -90 degree phase
`25 characteristic of the DMT carrier signal). An increased PAR
`can result in a system with high power consumption and/or
`with high probability of clipping the transmission signal.
`Thus, there remains a need for a system and method that can
`effectively scramble the phase of the modulated carrier sig-
`30 nals in order to provide a low PAR for the transmission signal.
`
`This application is a Continuation of U.S. application Ser.
`No. 13/439,605, filed Apr. 4, 2012, now U.S. Pat. No. 8,355,
`427, which is a Continuation of U.S. application Ser. No.
`13/284,549, filed Oct. 28, 2011, now U.S. Pat. No. 8,218,610,
`which is a continuation of Ser. No. 11/860,080, filed Sep. 24,
`2007, now U.S. Pat. No. 8,073,041, which is a divisional of
`U.S. application Ser. No. 11/211,535, filed Aug. 26, 2005,
`now U.S. Pat. No. 7,292,627, which is a continuation of U.S.
`application Ser. No. 09/710,310, filed on Nov. 9, 2000, now 15
`U.S. Pat. No. 6,961,369, which claims the benefit of the filing
`date of U.S. Provisional Application Ser. No. 60/164,134,
`filed Nov. 9, 1999, entitled "A Method For Randomizing The
`Phase Of The Carriers In A Multicarrier Communications
`System To Reduce The Peak To Average Power Ratio Of The
`Transmitted Signal," each which are incorporated by refer(cid:173)
`ence herein in their entirety.
`
`FIELD OF THE INVENTION
`
`This invention relates to communications systems using
`multicarrier modulation. More particularly, the invention
`relates to multicarrier communications systems that lower the
`peak-to-average power ratio (PAR) of transmitted signals.
`
`BACKGROUND OF THE INVENTION
`
`In a conventional multicarrier communications system,
`transmitters communicate over a communication channel
`using multicarrier modulation or Discrete Multitone Madu- 35
`lation (DMT). Carrier signals (carriers) or sub-channels
`spaced within a usable frequency band of the communication
`channel are modulated at a symbol (i.e., block) transmission
`rate of the system. An input signal, which includes input data
`bits, is sent to a DMT transmitter, such as a DMT modem. The 40
`DMT transmitter typically modulates the phase characteris(cid:173)
`tic, or phase, and amplitude of the carrier signals using an
`Inverse Fast Fourier Transform (IFFT) to generate a time
`domain signal, or transmission signal, that represents the
`input signal. The DMT transmitter transmits the transmission 45
`signal, which is a linear combination of the multiple carriers,
`to a DMT receiver over the communication channel.
`The phase and amplitude of the carrier signals of DMT
`transmission signal can be considered random because the
`phase and amplitude result from the modulation of an arbi- 50
`trary sequence of input data bits comprising the transmitted
`information. Therefore, under the condition that the modu(cid:173)
`lated data bit stream is random, the DMT transmission signal
`can be approximated as having a Gaussian probability distri(cid:173)
`bution. A bit scrambler is often used in the DMT transmitter 55
`to scramble the input data bits before the bits are modulated to
`assure that the transmitted data bits are random and, conse(cid:173)
`quently, that the modulation of those bits produces a DMT
`transmission signal with a Gaussian probability distribution.
`With an appropriate allocation of transmit power levels to 60
`the carriers or sub-channels, such a system provides a desir(cid:173)
`able performance. Further, generating a transmission signal
`with a Gaussian probability distribution is important in order
`to transmit a transmission signal with a low peak-to-average
`ratio (PAR), or peak-to-average power ratio. The PAR of a 65
`transmission signal is the ratio of the instantaneous peak
`value (i.e., maximum magnitude) of a signal parameter (e.g.,
`
`SUMMARY OF THE INVENTION
`
`The present invention features a system and method that
`scrambles the phase characteristics of the modulated carrier
`signals in a transmission signal. In one aspect, a value is
`associated with each carrier signal. A phase shift is computed
`for each carrier signal based on the value associated with that
`carrier signal. The value is determined independently of any
`input bit value carried by that carrier signal. The phase shift
`computed for each carrier signal is combined with the phase
`characteristic of that carrier signal to substantially scramble
`the phase characteristics of the carrier signals.
`In one embodiment, the input bit stream is modulated onto
`the carrier signals having the substantially scrambled phase
`characteristic to produce a transmission signal with a reduced
`peak-to-average power ratio (PAR). The value is derived from
`a predetermined parameter, such as a random number gen(cid:173)
`erator, a carrier number, a DMT symbol count, a superframe
`count, and a hyperframe count. In another embodiment, a
`predetermined transmission signal is transmitted when the
`amplitude of the transmission signal exceeds a certain level.
`In another aspect, the invention features a method wherein
`a value is associated with each carrier signal. The value is
`determined independently of any input bit value carried by
`that carrier signal. A phase shift for each carrier signal is
`computed based on the value associated with that carrier
`signal. The transmission signal is demodulated using the
`phase shift computed for each carrier signal.
`In another aspect, the invention features a system compris(cid:173)
`ing a phase scrambler that computes a phase shift for each
`carrier signal based on a value associated with that carrier
`signal. The phase scrambler also combines the phase shift
`computed for each carrier signal with the phase characteristic
`of that carrier signal to substantially scramble the phase char(cid:173)
`acteristic of the carrier signals. In one embodiment, a modu(cid:173)
`lator, in communication with the phase scrambler, modulates
`
`Page 7 of 12
`
`
`
`US 9,014,243 B2
`
`3
`bits of an input signal onto the carrier signals having the
`substantially scrambled phase characteristics to produce a
`transmission signal with a reduced PAR.
`
`DESCRIPTION OF THE DRAWINGS
`
`The invention is pointed out with particularity in the
`appended claims. The advantages of the invention described
`above, as well as further advantages of the invention, may be
`better understood by reference to the following description 10
`taken in conjunction with the accompanying drawings, in
`which:
`FIG. 1 is a block diagram of an embodiment of a digital
`subscriber line communications system including a DMT
`(discrete multitone modulation) transceiver, in communica(cid:173)
`tion with a remote transceiver, having a phase scrambler for
`substantially scrambling the phase characteristics of carrier
`signals; and
`FIG. 2 is a flow diagram of an embodiment of a process for
`scrambling the phase characteristics of the carrier signals in a
`transmission signal.
`
`4
`QAM symbols 58 in the frequency domain. In particular, the
`QAM encoder 42 maps the input serial data bit stream 54 into
`N parallel quadrature amplitude modulation (QAM) constel(cid:173)
`lation points 58, or QAM symbols 58, where N represents the
`number of carrier signals generated by the modulator 46. The
`BAT 44 is in communication with the QAM encoder 42 to
`specify the number of bits carried by each carrier signal. The
`QAM symbols 58 represent the amplitude and the phase
`characteristic of each carrier signal.
`The modulator 46 provides functionality associated with
`the DMT modulation and transforms the QAM symbols 58
`into DMT symbols 70 each comprised of a plurality oftime(cid:173)
`domain samples. The modulator 46 modulates each carrier
`signal with a different QAM symbol 58. As a result of this
`15 modulation, carrier signals have phase and amplitude char(cid:173)
`acteristics based on the QAM symbol 58 and therefore based
`on the input-bit stream 54. In particular, the modulator 46
`uses an inverse fast Fourier transform (IFFT) to change the
`QAM symbols 58 into a transmission signal 38 comprised of
`20 a sequence of DMT symbols 70. The modulator 46 changes
`the QAM symbols 58 into DMT symbols 70 through modu(cid:173)
`lation of the carrier signals. In another embodiment, the
`modulator 46 uses the inverse discrete Fourier transform
`(IDFT) to change the QAM symbols 58 into DMT symbols
`70. In one embodiment, a pilot tone is included in the trans(cid:173)
`mission signal 38 to provide a reference signal for coherent
`demodulation of the carrier signals in the remote receiver 34
`during reception of the transmission signal 38.
`The modulator 46 also includes a phase scrambler 66 that
`combines a phase shift computed for each QAM-modulated
`carrier signal with the phase characteristic of that carrier
`signal. Combining phase shifts with phase characteristics, in
`accordance with the principles of the invention, substantially
`scrambles the phase characteristics of the carrier signals in
`35 the transmission signal 38. By scrambling the phase charac(cid:173)
`teristics of the carrier signals, the resulting transmission sig(cid:173)
`nal 38 has a substantially minimized peak-to-average (PAR)
`power ratio. The phase scrambler 66 can be part of or external
`to the modulator 46. Other embodiments of the phase scram-
`40 bier 66 include, but are not limited to, a software program that
`is stored in local memory and is executed on the modulator
`46, a digital signal processor (DSP) capable of performing
`mathematical functions and algorithms, and the like. The
`remote receiver 34 similarly includes a phase descrambler 66'
`45 for use when demodulating carrier signals that have had their
`phase characteristics adjusted by the phase scrambler 66 of
`the DMT transceiver 10.
`To compute a phase shift for each carrier signal, the phase
`scrambler 66 associates one or more values with that carrier
`50 signal. The phase scrambler 66 determines each value for a
`carrier signal independently of the QAM symbols 58, and,
`therefore, independently of the bit value(s) modulated onto
`the carrier signal. The actual value(s) that the phase scrambler
`66 associates with each carrier signal can be derived from one
`or more predefined parameters, such as a pseudo-random
`number generator (pseudo-RNG), a DMT carrier number, a
`DMT symbol count, a DMT superframe count, a DMT hyper(cid:173)
`frame count, and the like, as described in more detail below.
`Irrespective of the technique used to produce each value, the
`same technique is used by the DMT transmitter 22 and the
`remote receiver 34 so that the value associated with a given
`carrier signal is known at both ends of the communication
`channel 18.
`The phase scrambler 66 then solves a predetermined equa(cid:173)
`tion to compute a phase shift for the carrier signal, using the
`value( s) associated with that carrier signal as input that effects
`the output of the equation. Any equation suitable for comput-
`
`DETAILED DESCRIPTION
`
`FIG. 1 shows a digital subscriber line (DSL) communica- 25
`tion system 2 including a discrete multitone (DMT) trans(cid:173)
`ceiver 10 in communication with a remote transceiver 14 over
`a communication