WO2004019545A1 - Method and apparatus for minima enlargement - Google Patents
Method and apparatus for minima enlargement Download PDFInfo
- Publication number
- WO2004019545A1 WO2004019545A1 PCT/US2003/025529 US0325529W WO2004019545A1 WO 2004019545 A1 WO2004019545 A1 WO 2004019545A1 US 0325529 W US0325529 W US 0325529W WO 2004019545 A1 WO2004019545 A1 WO 2004019545A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- symbols
- modulated signal
- threshold
- minima
- adjustment
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2614—Peak power aspects
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2626—Arrangements specific to the transmitter only
- H04L27/2627—Modulators
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/02—Channels characterised by the type of signal
- H04L5/06—Channels characterised by the type of signal the signals being represented by different frequencies
Definitions
- the present invention relates generally to a method and apparatus for minima enlargement.
- Wireless telecommunication systems sometimes are divided into a series of cell areas covering a service area.
- Each cell area has a transmitting base station using an operating frequency set comprising a plurality of radio channels to communicate with mobile subscribers.
- Each channel represents an information signal at a particular frequency carrier or band.
- the channels can all be combined by a broadband signal combiner into a multi-subchannel signal at lower power levels and then amplified by a single linear amplifier (or its equivalent, a plurality of linear amplifiers in parallel, each amplifying a reduced power version of the same multi-carrier subchannel signal) to raise the multi-subchannel signal to an appropriate transmit power level.
- a single linear amplifier or its equivalent, a plurality of linear amplifiers in parallel, each amplifying a reduced power version of the same multi-carrier subchannel signal
- Another application of multi-subchannel technology is to split the single, high symbol rate modulation into a plurality of lower rate sub-channels that each has a low enough modulation bandwidth to avoid the need for an adaptive equalizer.
- Highly linear multi-subchannel modulations have large dynamic ranges where the minimum voltage can approach -50 dB or lower from the signal mean. This will essentially take the linear amplifier used to increase the power of the signal prior to transmission down to idle bias current and cause a spike in the load impedance with unpredictable results.
- supply modulation techniques used to increase the linear amplifier efficiency if the supply voltage approaches zero, the linear amplifier could have problems with phase, noise and stability.
- floor clamp circuits have been employed to prevent the voltage from dropping below a specified threshold.
- FIG. 1 illustrates a block diagram of a transmit modem in accordance with the present invention
- FIG. 2 illustrates a pictorial representation of minima enlargement in accordance with the present invention.
- the present invention discloses an improved method and apparatus for minima enlargement in a modulator.
- the present invention allows control of the compression in accordance with the type of information being sent and will tailor symbols on multiple subchannels, including empty subchannels, in a controlled, individualized manner to improve the minima to average power ratio.
- FIG. 1 illustrates a block diagram of the transmit modem with the iterative minima enlarger.
- the block diagram comprises an unmodulated symbols input 100, a frequency division multiplexing ("FDM") modulator 102, a minima enlarger 104, and a summation component 106.
- the unmodulated symbols, X(k,m) 100 is the complex baseband symbol matrix with k selecting the frequency axis, and m selecting the time axis.
- the FDM modulator 102 modulates symbols according to the following equation:
- x(n) the 7 ⁇ th sample of the modulated output
- g the pulse shaping filter
- N s the pulse shaping filter length (in units of symbol periods)
- I the filter interpolation rate
- M the number of subchannels.
- the minima enlarger 104 detects signal minima and computes an adjustment matrix that when combined with the unmodulated symbols, X(k,m), 100 enlarges the signal above the minima threshold, M p .
- the signal minima is defined as any output sample whose magnitude is less than a specified minima threshold, M p .
- the minima threshold, M p can either be predetermined or dynamically adjusted based on system needs. When the signal drops below the minima, the problems discussed in the background manifest themselves.
- the adjustment matrix of the present invention brings the signal above the threshold and avoids the aforementioned problems.
- the summation component combines the unmodulated symbols, X(k,m),
- the minima enlarger 104 must find the ⁇ (k,m) such that:
- FIG. 2 pictorially illustrates minima enlargement.
- the magnitude of x(p) 200 is close to the origin, and hence the output of the linear amplifier is no longer reliable.
- ⁇ p 202, the phase of X ⁇ (P) 204 is the same as the phase of x(p)200. Making all contributions towards X ⁇ (P) 204 coherent in this direction minimizes the magnitude.
- the pulse-shaping filter is acting as a weighting function to the symbol adjustment matrix. Moving symbols that align with large filter coefficients have a greater impact on the magnitude than others.
- the pulse-shaping filter coefficients themselves can be used to weight the changes.
- ⁇ (k,m) it is noted that the various symbol types have different importance. For example, in most applications pilot and synchronization symbols should be altered much less than data symbols.
- W(k,m) as a matrix the same dimension as X(k,m) that contains weights for each entry in X(k,m). The complete equation for ⁇ (k,m) is given by:
- w r (n,m) is defined as the one-dimensional LFFT of W(k,m) along the frequency axis:
- the present invention provides a method and apparatus for receiving a plurality of symbols, and modulating the plurality of symbols to create a first modulated signal.
- the first modulated signal is then compared to a threshold. If the first modulated signal is above the threshold, the first modulated signal is transmitted. If the first modulated signal, however, is below the threshold, an adjustment to the received plurality of symbols is computed and added to the received plurality of symbols to create an adjusted plurality of symbols.
- the adjusted plurality of symbols is then modulated to create a second modulated signal.
- the second modulated signal is transmitted if it exceeds the threshold; otherwise, the steps of computing, adding and the second step of modulating are repeated until the modulated signal exceeds the threshold.
- the present invention provides a method and apparatus for receiving a plurality of symbols, mixing the plurality of symbols using an inverse fast Fourier transform to create a plurality of mixed symbols, and pulse shaping the plurality of mixed symbols to create a first modulated signal.
- the first modulated signal is then compared to a threshold. If the first modulated signal is above the threshold, the first modulated signal is transmitted. If the first modulated signal is below the threshold, an adjustment to the plurality of mixed symbols is computed and added to the plurality of mixed symbols to create an adjusted plurality of mixed symbols.
- Pulse shaping is performed on the adjusted plurality of mixed symbols to create a second modulated signal.
- the second modulated signal is transmitted if the second modulated signal exceeds the threshold; otherwise, the steps of computing, adding and the second step of pulse shaping are repeated until the modulated signal exceeds the threshold.
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2003262689A AU2003262689B2 (en) | 2002-08-22 | 2003-08-14 | Method and apparatus for minima enlargement |
IL16148903A IL161489A0 (en) | 2002-08-22 | 2003-08-14 | Method and apparatus for minima enlargement |
EP03793064A EP1540873A4 (en) | 2002-08-22 | 2003-08-14 | Method and apparatus for minima enlargement |
IL161489A IL161489A (en) | 2002-08-22 | 2004-04-19 | Method and apparatus for minima enlargement |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/225,982 | 2002-08-22 | ||
US10/225,982 US6754284B2 (en) | 2002-08-22 | 2002-08-22 | Method and apparatus for minima enlargement |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2004019545A1 true WO2004019545A1 (en) | 2004-03-04 |
Family
ID=31946317
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2003/025529 WO2004019545A1 (en) | 2002-08-22 | 2003-08-14 | Method and apparatus for minima enlargement |
Country Status (7)
Country | Link |
---|---|
US (1) | US6754284B2 (en) |
EP (1) | EP1540873A4 (en) |
AU (1) | AU2003262689B2 (en) |
IL (2) | IL161489A0 (en) |
MX (1) | MXPA04003749A (en) |
TW (1) | TWI239185B (en) |
WO (1) | WO2004019545A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2343861A3 (en) * | 2005-12-08 | 2011-08-17 | Hewlett-Packard Development Company, L.P. | Method of transmitting a multi-carrier signal and corresponding communications device |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7171245B2 (en) * | 2004-05-06 | 2007-01-30 | Chunghwa Telecom Co., Ltd. | Method for eliminating musical tone from becoming wind shear sound |
US8306486B2 (en) * | 2009-07-23 | 2012-11-06 | Panasonic Corporation | Methods and apparatus for reducing the average-to-minimum power ratio of communications signals in communications transmitters |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4700151A (en) * | 1985-03-20 | 1987-10-13 | Nec Corporation | Modulation system capable of improving a transmission system |
US6298094B1 (en) * | 1998-03-30 | 2001-10-02 | Motorola, Inc. | Method and apparatus for power control in a transmitter |
US6456669B1 (en) * | 1997-10-31 | 2002-09-24 | Sony Corporation | Data communication method, transmitter, and cellular radio communication system |
US6490269B1 (en) * | 1998-07-22 | 2002-12-03 | Sony Corporation | OFDM signal generation method and OFDM signal generation apparatus |
US6591090B1 (en) * | 1998-05-27 | 2003-07-08 | Nokia Mobile Phones Limited | Predistortion control for power reduction |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5469127A (en) * | 1992-08-04 | 1995-11-21 | Acrodyne Industries, Inc. | Amplification apparatus and method including modulator component |
US6134268A (en) | 1998-10-19 | 2000-10-17 | Motorola, Inc. | Apparatus for performing a non-integer sampling rate change in a multichannel polyphase filter |
US6147984A (en) | 1999-04-14 | 2000-11-14 | Motorola, Inc. | Method and apparatus for peak limiting in a modulator |
US6242975B1 (en) * | 1999-05-25 | 2001-06-05 | Conexant Systems, Inc. | Envelope peak and trough limiting to improve amplifier efficiency and distortion characteristics |
-
2002
- 2002-08-22 US US10/225,982 patent/US6754284B2/en not_active Expired - Fee Related
-
2003
- 2003-08-14 AU AU2003262689A patent/AU2003262689B2/en not_active Ceased
- 2003-08-14 IL IL16148903A patent/IL161489A0/en unknown
- 2003-08-14 WO PCT/US2003/025529 patent/WO2004019545A1/en not_active Application Discontinuation
- 2003-08-14 EP EP03793064A patent/EP1540873A4/en not_active Withdrawn
- 2003-08-22 TW TW092123200A patent/TWI239185B/en not_active IP Right Cessation
-
2004
- 2004-04-19 IL IL161489A patent/IL161489A/en not_active IP Right Cessation
- 2004-04-21 MX MXPA04003749A patent/MXPA04003749A/en active IP Right Grant
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4700151A (en) * | 1985-03-20 | 1987-10-13 | Nec Corporation | Modulation system capable of improving a transmission system |
US6456669B1 (en) * | 1997-10-31 | 2002-09-24 | Sony Corporation | Data communication method, transmitter, and cellular radio communication system |
US6298094B1 (en) * | 1998-03-30 | 2001-10-02 | Motorola, Inc. | Method and apparatus for power control in a transmitter |
US6591090B1 (en) * | 1998-05-27 | 2003-07-08 | Nokia Mobile Phones Limited | Predistortion control for power reduction |
US6490269B1 (en) * | 1998-07-22 | 2002-12-03 | Sony Corporation | OFDM signal generation method and OFDM signal generation apparatus |
Non-Patent Citations (1)
Title |
---|
See also references of EP1540873A4 * |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2343861A3 (en) * | 2005-12-08 | 2011-08-17 | Hewlett-Packard Development Company, L.P. | Method of transmitting a multi-carrier signal and corresponding communications device |
Also Published As
Publication number | Publication date |
---|---|
MXPA04003749A (en) | 2004-07-23 |
US6754284B2 (en) | 2004-06-22 |
EP1540873A4 (en) | 2010-06-16 |
IL161489A (en) | 2009-07-20 |
EP1540873A1 (en) | 2005-06-15 |
TWI239185B (en) | 2005-09-01 |
AU2003262689B2 (en) | 2005-09-01 |
AU2003262689A1 (en) | 2004-03-11 |
TW200420069A (en) | 2004-10-01 |
IL161489A0 (en) | 2004-09-27 |
US20040042540A1 (en) | 2004-03-04 |
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