Multi-carrier LAN adapter device using frequency domain equalizer

(12) United States Patent

Dobson

US006507585B1

(io) Patent No.: US 6,507,585 Bl (45) Date of Patent: Jan. 14,2003

(54) MULTI-CARRIER LAN ADAPTER DEVICE USING FREQUENCY DOMAIN EQUALIZER

(75) Inventor: William Kurt Dobson, Sandy, UT (US)

(73) Assignee: 3Com Corporation, Santa Clara, CA (US)

( * ) Notice: Subject to any disclaimer, the term ol this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.

(21) Appl. No.: 09/085,653

(22) Filed: May 27, 1998

(51) Int. CI.7 H04L 12/28

(52) U.S. CI 370/420; 370/401; 375/220;

375/223

(58) Field of Search 370/401, 419,

370/421, 290, 307, 478, 352, 208, 203, 206, 210, 497, 494; 375/222, 223, 260, 219, 229, 231, 235, 269, 272, 316, 322

FOREIGN PATENT DOCUMENTS

(56)

References Cited U.S. PATENT DOCUMENTS

3,679,882 A 7/1972 McAuliffe 235/152

4,106,103 A 8/1978 Perreault 364/827

4.152.649 A 5/1979 Choquet 325/42

4,227.152 A 10/1980 Godard et al 375/13

4,233,589 A 11/1980 Rawson et al 340/147

4,247,908 A 1/1981 Lockhart, Ir. et al 364/900

4,345,250 A 8/1982 lacobsthal 340/825.5

4,430,743 A 2/1984 Watanabe 333/18

4,509.206 A 4/1985 Carpe et al 455/245

4,519,074 A 5/1985 Basile 370/124

4,539,689 A 9/1985 Chiu et al 375/13

4,652,874 A 3/1987 Loyer 340/825.05

4,745,600 A 5/1988 Herman et al 370/95

4,751.701 A 6/1988 Roos et al 370/85

4,760.375 A 7/1988 Stecker 340/310

4,881,222 A 11/1989 Goeckler et al 370/70

4.885.742 A 12/1989 Yano 370/85.2

4.885.743 A 12/1989 Helbers et al 370/85.2

4,899,217 A 2/1990 MacFadyen et al 358/86

4,901,342 A 2/1990 lones 379/93

(List continued on next page.)

A LAN Adapter device having a frequency domain equalizer. The LAN adapter device allows LAN computing devices to connect to the LAN medium. The adapter devices are internal or external to the LAN devices and provide a transceiver and protocol stacks for the LAN devices to communicate with each other. The physical layer ol the transceivers includes transmitter having a DMT modulator and demodulator that is dynamically configurable with respect to data rate and spectrum usage. Within the receiver is an equalizer for equalizing the received signal with a simple yet effective equalizer training method, thereby obviating the need for extensive equalizer training and long-term coefficient storage. The equalizer trains on known symbols transmitted in one frame ol a transmitted packet to determine an estimate ol the channel response. The remaining frames that are modulated with data are equalized based on an estimate ol the channel response determined from interpolating between the points previously determined from the known symbols.

20 Claims, 6 Drawing Sheets

U.S. PATENT DOCUMENTS

4,943,980 A 7/1990 Dobson et al 375/42

4,959,713 A 9/1990 Morotomi et al 358/108

4.965.792 A 10/1990 Yano 370/85.2

5,003,579 A 3/1991 Jones 379/93

5,051,720 A 9/1991 Kittiratsunetom 340/310

5,117,418 A 5/1992 Chaffee et al 370/32.1

5,121,414 A 6/1992 Levine et al 375/96

5,128,964 A 7/1992 Mallory 375/39

5.130.793 A 7/1992 Bordry et al 358/86

5,166,924 A 11/1992 Moose 370/32.1

5,195,106 A 3/1993 Kazecki et al 375/12

5,197,066 A 3/1993 Sutterlin 370/85.3

5,206,886 A 4/1993 Bingham 375/97

5,210,530 A 5/1993 Kammerer et al 340/825.08

5,226,081 A 7/1993 Hinokimoto 380/34

5,228,062 A 7/1993 Bingham 375/97

5,278,844 A 1/1994 Murphy et al 371/37.1

5.285.474 A 2/1994 Chow et al 375/13

5,313.169 A 5/1994 Fouche et al 329/302

5,317,596 A 5/1994 Ho et al 370/32.1

5,319,674 A 6/1994 Cherabini 375/101

5,329,552 A 7/1994 De Couasnon et al 375/59

5,353,287 A 10/1994 Kuddes et al 370/85.2

5,355.375 A 10/1994 Christensen 370/85.2

5,377,327 A 12/1994 Jain et al 395/200

5,400,322 A 3/1995 Hunt et al 370/19

5,410,292 A 4/1995 Le Van Suu 340/310.06

5,461,640 A 10/1995 Gatherer 375/231

5,479,447 A 12/1995 Chow et al 375/260

5,519.727 A 5/1996 Okanoue et al 375/232

5,519,731 A 5/1996 Cioffi 375/260

5,521,908 A 5/1996 Younce et al 370/32.1

5,521,937 A 5/1996 Kondo et al 375/206

5,539,777 A 7/1996 Grube et al 375/316

5.553.008 A 9/1996 Huang et al 364/578

5,568,476 A 10/1996 Sherer et al 370/60

5,570,350 A 10/1996 Myer et al 370/18

5,572,511 A 11/1996 Ouyang et al 370/13

5,572,546 A 11/1996 Serfaty et al 375/221

5,592.482 A 1/1997 Abraham 348/8

5,596.577 A 1/1997 Perreault et al 370/449

5,596,604 A 1/1997 Cioffi et al 345/260

5,598,401 A 1/1997 Blackwell et al 379/94

5,606,577 A 2/1997 Grube et al 375/295

5,608,725 A 3/1997 Grube et al 370/338

5,621.662 A 4/1997 Humphries et al 364/550

5,625,651 A 4/1997 Cioffi 375/354

5,625,871 A 4/1997 Myer et al 455/33.1

5,627,828 A 5/1997 Lee 370/445

5,627,863 A 5/1997 Aslanis et al 375/357

5,636.211 A 6/1997 Newlin et al 370/465

5,636.246 A 6/1997 Tzannes et al 375/260

5.651.009 A 7/1997 Perrault et al 370/447

5,655,140 A 8/1997 Haddock 395/200.76

5,659,891 A 8/1997 Hays et al 455/103

5,668,802 A 9/1997 Chalmers et al 370/276

5,671.251 A 9/1997 Blackwell et al 375/222

5,673,290 A 9/1997 Cioffi 375/260

5.694.395 A 12/1997 Myer et al 370/480

5.694.396 A 12/1997 Firouzbakht et al 370/480

5,729,570 A 3/1998 Magill 375/206

5,909.463 A 6/1999 Johnson et al 375/220

6,005.893 A 12/1999 Hyll 375/260

6,021,158 A * 2/2000 Schurr 375/211

6,069,899 A 5/2000 Foley 370/494

6,101,182 A 8/2000 Sistanizadeh et al 370/352

6.101.216 A 8/2000 Henderson et al 375/222

6,130.893 A * 10/2000 Whittaker 370/420

6,154,465 A 11/2000 Pickett 370/466

OTHER PUBLICATIONS

Edfors, O., Sandell, M., Van De Beek, J., Wilson, S., Borjesson, P., OFDM Channel Estimation by Singular Value Decomposition, Division of Signal Processing, Lulea University of Technology, Lulea, Sweden, Purdue University, School of Electrical and Computer Engineering, West Lafayette, Indiana, Pgs. 1-5.

Nilsson, R., Edfors, O., Sandell, M., Borjesson, P., An Analysis of Two-Dimensional Pilot-Symbol Assisted Modulation for OFDM, Division of Signal Processing, Lulea University of Technology, Sweden, Department of Applied Electronics, Lund University, Lund, Sweden, Lucent Technologies, Bell Labs, Windmill Hill Business Park, Swindon, UK, Pgs. 1-4.

Wahlqvist, M., Ostberg, C, Van De Beek, J., Edfors, O., Borjesson, P., A Conceptual Study of OFDM-Based Multiple Access Schemes, Part l:Air Interface Requirements, Lulea University of Technology, Lulea, Sweden, Telia Research, Lulea, Sweden, Pgs. 1-7.

Van De Beek, J., Edfors, O., Borjesson, P., Wahlqvist, M.,
Ostberg, C, A Conceptual Study of OFDM-Based Multiple
Access Schemes, Part 2: Channel Estimation in the Uplink,
Lulea University of Technology, Lulea, Sweden, Telia
Research, Lulea, Sweden, Pgs. 1-7.

Van De Beek, J., Edfors, O., Borjesson, P., Wahlqvist, M.,
Ostberg, C, A Conceptual Study of OFDM-Based Multiple
Access Schemes, Part 3: Performance Evaluation of a Coded
System, Lulea University of Technology, Lulea, Sweden,
Telia Research, Lulea, Sweden, Pgs. 1-6.
Antipolis, Sophia, A Conceptual Study of OFDM-Based
Multiple Access Schemes, Part 4: Tracking of Time and
Frequency Offset, Telia Research, Dec. 1996, Pgs. 1-12.
Van De Beek, J., Sandell, M., Borjesson, P., ML Estimation
of Timing and Frequency Offset in Multicarrier Systems,
Division of Signal Processing, Lulea University of Technol-
ogy, Lulea, Sweden, Apr., 1996, Pgs. 1-24.
Sandell, M., Edfors, O., A Comparative Stud y of Pilot-
Based Channel Estimators for Wireless OFDM, Sep. 1996,
Pgs. 1-34.

Lulea University of Technology, Division of Signal Processing, Synchronization in OFDM, Mar. 27, 1998, Pgs. 1-3. Van De Beek, J., Sandell, M., Borjesson, P., On Synchronization in OFDM Systems Using the Cyclic Prefix, Division of Signal Processing, Lulea University of Technology, Lulea, Sweden, Pgs. 1-5.

Van De Beek, J., Sandell, M., Isaksson, M., Borjesson, P., Low-Complex Frame Synchronization in OFDM Systems, Division of Signal Processing, Lulea University of Technology, Lulea, Sweden, Telia Research, Lulea, Sweden, Pgs. 1-5.

Isaksson, Mikael, Proposal: Option for In-Band POT and
ISDN, Standards Project: T1E1.4:VDSL Sep. 22-26, 1997,
Pgs. 1-5.

Sandell, M., Van De Beek, J., Borjesson, P., Timing and
Frequency Synchronization in OFDM Systems Using the
Cyclic Prefix, Division of Signal Processing, Lulea Univer-
sity of Technology, Lulea, Sweden, Pgs. 1-4.
Edfors, O., Sandell, M., Van De Beek, J., Wilson, S.,
Borjesson, P., Analysis of DFT-Based Channel Estimators
for OFDM, Vehicular Technology Conference (VTC'96),
Chicago, Illinois, Jul. 25-28, 1995, Pgs. 1-25.
Edfors, O., Sandell, M., Van De Beek, J., Landstrom, D.,
Sjoberg, F, An Introduction to Orthogonal Frequency-Di-
vision Multiplexing, Sep. 1996, Pgs. 1-58.
Edfors, Ove, Low-Complexity Algorithms in Digital
Receivers, Doctoral Thesis, Lulea University of Technology,
Sep. 1996, Pgs. 1-190.

* cited by examiner