TW200908599A - System and method of transmitting and receiving an OFDM signal with reduced peak-to-average power ratio - Google Patents

Abstract

A method transmits data by generating (110-i) a plurality of candidate orthogonal frequency division multiplex (OFDM) signals, selecting (120) the candidate OFDM signal that has the lowest peak-to-average-power ratio, and transmitting (130) the selected OFDM signal. Each of the candidate OFDM signals is generated by inserting (112, 200) a set of one or more dummy bits before a data bit sequence to produce an input bit sequence, recursively convolutionally encoding (114) the input bit sequence to generate an encoded bit sequence, interleaving (166) the encoded bit sequence, and OFDM modulating (118) the interleaved, encoded bit sequence to generate the candidate OFDM signal. The set of one or more dummy bits for each of the candidate OFDM signals is different than the set of one or more dummy bits for each of the other candidate OFDM signals.

Description

200908599 IX. Description of the Invention: [Technical Field of the Invention] The present invention relates to the field of data communication, and more specifically, to a transmission and reception of an orthogonal cheek multi-tower (OFDM) signal. System and method. [Prior Art] There is a need for more flexible and efficient resources to develop new communication system communication technologies.

ϋ For one of the wireless communication systems, s I & 仃 is selected as Orthogonal Frequency Division Multiplexing (OFDM). For example, the Worldwide Interoperability for Microwave Access (wiMAx) standard and

Both WiMedia Ultra Wideband (UWB) universal radio platforms use OFDM. OFDM is an efficient transmission method for high data rate wireless communication applications due to its robustness to frequency selective fading, high frequency efficiency, and ease of implementation. Therefore, OFDM is an attractive technology for wireless communication applications. However, there are some limitations and disadvantages of OFDM signals. One of the main drawbacks of 〇FDM is the peak-to-average power ratio (pApR) of OFDM signals. The OFDMk number with high PAPR imposes poor design choices on the output power amplification stage. If the amplifier is selected based on the average power of the transmitted 〇FDM signal, the peak of the OFDM signal can overload the power amplifier and cause intra-band distortion and out-of-band emissions. In-band distortion increases the bit error rate (BER) and out-of-band emissions cause unacceptable adjacent channel interference. On the other hand, the output power amplifier can have a sufficiently high compression point to handle the peak of the OFDM signal and provide a linear response. However, in general, this 132011.doc 200908599 amplifier will be badly large, inefficient, and will consume too much power. Many different mechanisms for reducing the PAPR of OFDM signals have been proposed. Basically, these mechanisms can be grouped into two categories. The mechanism belonging to the first category deliberately modifies the transmitted OFDM signal such that the peak is suppressed. X. Li et al.

Filtering on the P erformance of OFDM'' (IEEE

Communications Letters, Vol. 2, No. 5, pp. 131-133, May 1998) is an example of a reference to reveal the PAPR reduction mechanism in this first category. However, deliberate modification of the operation itself can introduce in-band noise' which can reduce the bit error rate (BER) performance of the transmission. The simplest solution in this category is to intentionally cut OFDM signals. Instead, the mechanism in the second category generates a plurality of modulated OFDM signals for a given data sequence at the transmitter, and then selects the OFDM signal with the lowest PAPR to be transmitted. These mechanisms do not cause distortion of the OFDM signal, but the implementation is at the expense of increased complexity at the transmitter. Partial Transfer Sequence (PTS) and Selective Mapping (SLM) are two types of mechanisms in this category. Power of L.J. Cimini, Jr., etc.

Reduction of an OFDM Signal Using Partial Transmit Sequences'' (IEEE COMMUNICATIONS LETTERS » No. 4, pp. 86-88, March 2000) and C. Tellambura's "P/zase Optimization criterion for reducing peak-to-average power Ratio in OFDM" (ELECTRONIC LETTERS, Vol. 43, No. 2, pp. 169-170, 1998) discloses a mechanism for using PTS. 132011.doc 200908599 Meanwhile, PV Eetvelt et al. "ΡβαΑ: ίο Jwotge Power Reduction for OFDM Schemes by Selective Scrambling'' (Electronic Letters, Vol. 32, pp. 1963-1964, October 1996); S. Muller Etc. "6>77£> From Sun "do/^£/«<^<^ 尸6(3众-^〇-

Average Power Ratio by Multiple Signal Representation'' (Annals of Telecommunications, Vol. 52, No. 1-2, pp. 58-67, 1997); N. Chen et al. "Crew Facior Reduction in OFDM Using Blind Selected Pilot Tone Mo Office/αίζ·(10)” (US Patent Application Publication No. US2006274868A1); and M. Breiling ^ A &"SLM Peak-Power Reduction Without Explicit Side Information” (IEEE COMMUNICATIONS Letters, Vol. 5, No. 6, Pages 239-241, June 2001) all reveal mechanisms for using SLM. Also, several methods have been proposed for reducing the PAPR of the transmitted OFDM signal in a space-time coded OFDM system. For example, H. Reddy's "Space-Time Coded OFDM with Low PAPR" (IEEE Global Telecommunications Conference, Vol. 2, pp. 799-803, December 2003) reveals a PAPR reduction mechanism based on lattice shaping. . It can effectively reduce the PAPR of OFDM signals. However, due to lattice shaping, spectral efficiency is reduced. Furthermore, due to error propagation, BER performance is worse than BER performance in the case of non-lattice shaping mechanisms. Meanwhile, YL Lee et al. "PeaAr-io-dverage Power Λαίζ'ο in MI MO-OFDM Systems Using Selective Mappin" (ΥΕΈΈ Communications Letters, Vol. 7, No. 12, 575-577 132011.doc 200908599 Page, December 2003) proposes an SLM-based PAPR reduction mechanism for Multiple Input Multiple Output (MIMO) OFDM systems. The proposed mechanism selects the sequence with the lowest average pApR transmitted on all transmitted antennas. Producing a sufficiently different candidate OFDM signal for each input information bit sequence and selecting the signal with the lowest pApR to be transmitted. There are several ways to generate a pseudo-random candidate OFDM signal. In Lee et al. The c/randomized phase rotation vectors are used to randomize the frequency domain OFDM symbols to the right and then generate the candidate 〇FDM signals. Meanwhile, in the Breiling et al. literature, the author uses the scrambler to disturb the input information bits. Yuan, and /7 virtual bits are used to set the scrambler to different initial states. In the case of "different values of virtual bits", a pseudo-slave can be generated. Machine candidate OFDM signals. However, such prior mechanisms in the second category also have disadvantages. In some cases, the index of the phase rotation vector corresponding to the transmitted OFDM signal needs to be explicitly transmitted to the receiver, usually as a side Information. This increases the number of additional items and reduces the amount of data delivered. In addition, due to the incorrect phase derotator used, errors in detecting this side information can cause error propagation. Additional complexity is added to the receiver, such as the addition of a descrambler. Also, for example, the mechanism disclosed by Chen requires a 〇FDM pilot tone with power substantially greater than the power level of the normal OFDM symbol: Quasi, and therefore it is not suitable for some popular 〇fdm systems, such as, 132011 .doc 200908599

WiMAX and WiMedia UWB In addition, channel coding is not considered in some of these mechanisms, but in the most realistic OFDM systems, channel coding is used before the 〇FDM modulator achieves frequency diversity and reduces BER (including staggered). Therefore, it would be desirable to provide a system and method for transmitting and receiving OFDM signals having reduced p APR. [Summary of the Invention]

In one aspect of the invention, a method for transmitting data is provided. The method includes generating a plurality of candidate orthogonal frequency division multiplexing (〇dfm) signals, wherein generating each of the specialized candidate OFDM signals includes inserting a set of one or more dummy bits before a data bit sequence Generating an input bit sequence, recursively encoding the input bit sequence to generate an encoded bit sequence, interleaving the encoded bit sequence, and 〇fdm modulating the interleaved encoded bit sequence to generate The candidate 〇fdm signal; selecting one of the plurality of candidate 〇Fdm signals having a low peak-to-average power ratio and transmitting the selected 〇FDM signal. The e of each of the candidate 〇fdm signals One or more virtual bits of the group are different from the group of one or more virtual bits of each of the other candidate 〇FDM signals. In another aspect of the invention, a system for transmitting data includes : a plurality of candidate orthogonal frequency division multi-weiler (qFDm) signal generators, each OF^ML number generation comprising a virtual bit inserter adapted to insert a set of one or more before the data bit sequence Virtual bit to generate an input bit a sequence, a recursive cyclocoder, which is located in sequence and produces an encoded bit sequence adapted to receive the input 'an interleaver, which is adapted to interleave the encoded bit 132011.doc -10- 200908599 a sequence, a FE) M modulator adapted to receive the interleaved encoded bit sequence and to generate a candidate OFDM signal; a signal selector adapted to select a lowest peak to average power ratio And - a transmitter adapted to transmit the selected 〇 FDM signal. The set of each of the candidate OFDM signal generators - or a plurality of dummy bits The element is different from the set of one or more virtual bits of each of the other itCT signals.

Cc In yet another aspect of the invention, a data receiver includes: an orthogonal frequency division multiple security (OFDM) demodulator adapted to receive a subtle speech and output-interleaved coding a sequence of bits; a deinterleaver, adapted to receive the interleaved encoded bit sequence and output-encoded bit sequence; a convolutional decoder adapted to decode the encoded bit The sequence and the output-output bit sequence; and - the virtual bit removed ^, should be adapted to remove a set of - or more virtual bits and output - data bits; columns. [Embodiment] In the following embodiments, the exemplary embodiments are described for the purpose of understanding the embodiments of the present invention. However, the “common familiarity” that e has benefited from this disclosure is obvious, and it is clear from the name of the Fufu Xi’s in this article—we’ll take the wu, and the details of the temple’s details according to the teachings. The scope of the patent scope is still available at any time. In addition, the description of well-known devices and methods is not described in the following. These methods and devices are obviously within the teachings of this teaching example 132011.doc 200908599 Figure 1 Functional block diagram of an embodiment of an orthogonal frequency division multiplexing (〇FDM) transmission system. As will be appreciated by those skilled in the art, a microprocessor-controlled, hard-wired (hard-Wd) logic circuit Or a combination thereof to physically implement the various functions shown in Figure 1. Similarly, although the functional blocks are illustrated as separate in Figure i for purposes of explanation, they may be combined in any physical embodiment. The OFDM transmission system 1 复 includes a plurality of (for example, "" candidate employment signal generators 1HM, a signal selector 12〇, and a transmitter 13〇. Each 〇FDMj5 generator 11〇_' Contains: a virtual bit inserter "2, a recursive cyclocoder 114 An interleaver U6 and a 〇 FDM modulator 118. The OFDM modulator 118 includes a symbol mapper 14 〇 a time domain transformer 150. In the OFDM transmission system 〇〇, the time domain converter 15 〇 includes an inverse fast Fourier Inverter (IFFT), but other embodiments may be used. In the FDM transmission system 100, the transmitter 13A includes an orthogonal space_time block coding benefit (OSTBC) 132 and a spatial diversity transmission including the antenna system 134. System. Other transmission configurations using only a single antenna may be used. Although not shown in Figure 1, the guard interval (loop preamble) may be used to insert/remove blocks in the OFDM transmission system 1 。. However, because This block does not affect the peak-to-average power ratio (PAPR) of the OFDM signal, so it will be omitted from Figure 1 to simplify the following diagram and discussion. OFDM Transmission System 1 〇〇 The following operations are provided. a candidate 〇 FDM signal generator 110-Z. Each candidate OFDM signal generator 110-/ generates a unique candidate OFDM signal from the data bit sequence. The signal selector 120 is selected from the candidate OFDM signals 132011.doc -12· 200908599 The lowest peak-to-average power ratio (PAPR) signal and the selected OFDM signal is provided to the transmitter 13, and the transmitter (10) then transmits the selected OFDM signal with the lowest PAPR. In each-candidate OFDM signal generator _, the channel code It is used to adopt frequency diversity and improve ship performance. Advantageously, the channel stone is a recursive convolutional code, and its feedback part can be regarded as a scrambler. The input bit sequence is input to the recursive cyclocoder 丨 。 4. Then, The encoded bits pass through the bit interleaver 116 and are mapped by the symbol mapper 14 为 to the symbol heart 'Ml』) from the symbol asterisk 〇, where the number of subcarriers in the m 〇 fdm symbol. The resulting symbols are grouped into and passed to the ifpt 150 to output the candidate OFDM signal. A complex baseband OFDM signal can be expressed as

(1) ViV (4) >0<t<NT where 'f(k)=k*M, Μ=1/(ΝΤ) ' and NT is the 〇FDM symbol interval length. The OFDM transmission system 100 is a space-time encoded 〇Fdm system, and thus the 'OSTBC 132 is included in the transfer key behind the OFDM modulator 118. For example, the signals transmitted by § 'total §' are generated based on two consecutive OFDM signals (7) and c2 (7) using the so-called Alamouti mechanism. In the first OFDM symbol interval, X/(%) is transmitted via the first antenna of the antenna system 134, and the heart (7) is transmitted via the second antenna of the antenna system 134. In the second OFDM symbol interval, transmitted via the first antenna and transmitted via the second antenna [/, where (·)* 132011.doc -13- 200908599 represents a complex conjugate. However, it should be understood that in other embodiments of an OFDM transmission system that does not use spatial diversity, OSTBC 1 32 may be omitted and antenna system 134 may use only a single antenna. The PAPR of the OFDM signal in equation (1) can be defined as

PAPR (2) max |x(〇| Q<t<NT' ' E{\x(tf) 2

Where E{·} represents the desired operation. It can be shown that when the oversampling rate L is large, the PAPR defined in (2) can be accurately approximated as:

PAPR max \x„ 0<t<LN' (3) where Xm (for w£w<LA〇 is a time domain signal sample and is defined as: (4)

N_~[ jl^cm 4n k=0

>0<m<LN

The OFDM transmitter 100 generates t/sufficient candidate OFDM signals for each input information bit sequence and selects the signal with the lowest PAPR to be transmitted. In particular, different patterns of n virtual bits are used in each candidate OFDM signal generator 110-/ to set each corresponding recursive cyclocoder 1 1 4 to a different initial state. In the case of "different values of virtual bits", a pseudo-random candidate OFDM signal can be generated. Channel coding can use frequency diversity and improve BER performance. Similarly, interleaver 116 and non-linear symbol mapper 118 can increase the pseudo-randomness of candidate OFDM signals. As will be seen below, at the data receiver, the descrambler is not required, 132011.doc -14-200908599 and only a Viterbi decoder is needed to decode the recursive convolutional code. The Viterbi decoder does not change the complexity of receiving a similar OFDIv/Hf number without PAPR, with the constraint that the feedback polynomial of the back % code used by the recursive cyclocoder ι 4 does not increase the memory length. Furthermore, since there is no error propagation, there is no BER performance loss due to PAPR reduction. '

In the first embodiment, virtual bit inserter i 12 inserts "virtual bit elements directly" before the data bit of the data bit sequence to produce an input bit sequence applied to recursive cyclocoder 114. In the case of a different value of the virtual bit, the recursive cyclocoder 114 of the C/ candidate OFDM signal generator 丨1〇d can be set to f/ different initial states. The virtual ^ of the binary representation of the virtual bit inserter D, ·, Mm), & in Fig. i is inserted before a sequence of data bits to produce an input bit sequence. The input bit sequence is then input to a recursive cyclocoder 1丨4 to produce an encoded bit sequence. The encoded bit sequence is provided to interleaver 116 to produce an interleaved encoded bit sequence. Finally, the parent-coded bit sequence is provided to 〇F DM modulator 118 to generate A different candidate OFDM signal. However, in the case of this embodiment, there is a constraint that the memory length of the whirling code should be larger than the number η of virtual bits. In addition, there must be two different values of "one virtual bit" that set the recursive cyclocoder 1 14 to the same initial state, which means that there are two candidate 〇FDM signals that are identical to each other. Therefore, the PAPR reduction is reduced. Figure 2 is a functional block diagram of another embodiment of a virtual bit insertion 132011.doc -15-200908599 device 200 that can be used in the OFDM transmission system of Figure 1. As will be appreciated by those skilled in the art. The various functions shown in Figure 2 are physically implemented using a software controlled microprocessor, a fixed line logic circuit, or a combination thereof. Again, although the functional blocks are illustrated as separate in Figure 2 for purposes of explanation, It is combined in any of the physical embodiments. The virtual bit inserter 200 includes a Hamming encoder 210 and a bit flipper 220.

The Hamming encoder 210 receives the first group (2"-heart 1) data bits of the length data bit sequence and generates a Hamming-coded bit sequence of length (2«-" therefrom. The bit flipper 22 flips the first bit of the sequence of the Hamming coded sequence (where (χκο, to output the length of the output bit sequence (2^). The bit flipper 220 intentionally A bit error in the sequence of bits is introduced by flipping one of the bits output by the Hamming encoder 210. The virtual bit inserter then outputs a second group of data bit sequences (F-«- [2*^-1])=^^2"+1) bits are used as the first group of bits of the output bit sequence. Therefore, the virtual bit inserter 2 receives the data bit of the length (F_w) a sequence, and outputting a sequence of output bits comprising F bits. When the meta-interpolator 200 is used in the candidate OFDM signal generator 丨丨〇_丨 of the figure, the output bit sequence is used as the input bit sequence. Applied to the recursive cyclocoder 114. For the candidate camphor signal generator 11 (each of which is flipped by the Hamming coded sequence - The same bit (including any bit that does not flip one of the signal generators lio-ί). Therefore: 13201J.doc -16- 200908599 • The bite mountain coded by Hamming, 1 s (2M), and • Other tributary bits di=b(i_n), 2" eve < corpse returning gyro encoder 114 for channel coding. Because han == error, deliberate ~ - bit error can be edited:: Hamming decoder correction 'its constraint is that all Hamming code bits 4 are correctly detected. Recursive whirling coder 114, bit intersection and non-linear mapper (10) can save different candidate points, making achievable Good PAPR reduces performance. "In this embodiment, there is no constraint on the memory length of the whirling code. In the above two embodiments, because the virtual bit_human operation, the revolving, the wide interleave is a linear operation, So only need to generate - corresponding to the virtual: insert: (d) a single interlaced convolutional codeword group. Calculate the other by adding a predicted 7L sequence to the interlaced convolutional codeword group % The interleaved whirling codeword group of the virtual bit inserter 112. This inter-transfer Design. Because of the need to perform a thank-you operation on the transmitter side, the complexity of the transmitter is increased to provide improved PAPR performance. However, the complexity of the data receiver remains almost unchanged. The ancient map 3 is -〇FDM data reception Functional block diagram of the embodiment of the device. As will be appreciated by those skilled in the art, various functions as shown in FIG. 3 can be physically implemented using a software control microprocessor, a fixed line: logic circuit, or a combination thereof. Likewise, although the functional blocks are illustrated as separate for purposes of explanation in FIG. 3, they may be combined in any of the physical embodiments. An orthogonal frequency division multiplexing one cyclotron decoder 340 data receiver 300 includes An antenna system 31 〇, (OFDM) demodulation transformer 320, a deinterleaver 330, 132011.doc • 17· 200908599 and a virtual bit remover 350. The OFDM demodulator 32A includes a first frequency domain converter 322-丨 and a second frequency domain converter 322-2, an orthogonal spatial-temporal block coding (〇STBC) decoder 324, and a _0FDM symbol in place. Meta converter or demapper. In one embodiment, the first frequency domain converter 322-1 and the second frequency domain converter 322-2 are each a fast Fourier transformer (FFT). The data receiver 300 operates to receive a space-time encoded 〇FDM signal. However, it should be understood that in other embodiments of the 〇FDM receiver, spatial diversity is not used, and the antenna system 310 can use only a single antenna, and the OFDM demodulation transformer 32 can include only a single frequency domain converter, and can The OSTBC decoder 324 is omitted. The 〇FDM demodulation transformer 320 receives the OFDM signal including the OFDM symbol and outputs an interleaved encoded bit sequence. If space-time coding (e.g., M_-0FDM configuration) is used, the still-% decoder 324 performs spatial time code decoding after only the frequency domain is changed. Deinterleaver 33q receives the interleaved encoded bit sequence, deinterleaves the bit sequence, and outputs the encoded bit sequence. The cyclotron decoder 34G decodes the encoded bit sequence and outputs an output bit sequence. The virtual bit remover 35 removes the "virtual bit, and outputs - the sequence of data bits from the bit sequence. In the embodiment the virtual bit remover 350 includes a Hamming decoder 352 to remove one or more virtual bits inserted by the virtual bit inserter 200 into the transmitted bit sequence. In the following FIGS. 4 to 6, it is shown that the curve of type 4" corresponds to the first embodiment virtual bit inserter (1), 13201I.doc -18-200908599 described above with respect to the figure! The curve denoted as ', type-3' corresponds to the second embodiment virtual bit inserter' example of which is the virtual bit inserter 2 shown in Figure 2. Figure 4 depicts the use of 根据 according to various embodiments The peak-to-average power ratio of the OFDM signal generated by the FDM transmission system is reduced. In these simulations, the number of OFDM subcarriers is "128, and the astrological sign is 16 (^河. Using the industry standard % rate whirling code [ 133 171], and the memory length of this code is 6. This code is modified to be in a recursive form with a feedback polynomial of 133. The theoretical PAPR performance curve is also depicted as a reference. These theoretical results are well matched to the Type-2 embodiment. Simulation results. For the same number of virtual bits, the Type-2 embodiment consistently exhibits PAPR performance better than the pApR performance of the Type_丨 embodiment, but with the increase, the performance gap between the two mechanisms is reduced. Small. In two ( 2) In the case of virtual bits, the type-1 mechanism can achieve a PAPR reduction of approximately 21 dB under the probability of 丨〇_4, and the type_2 mechanism can achieve a PAPR reduction of approximately 2.7 dB. In three (3) virtual In the case of a bit, a reduction of about 3·4 dB2 PApR can be achieved at a probability of ΙΟ4. When four (4 > virtual bits are used, a reduction of about 4 dBi pApR can be achieved. However, this improved implementation is required Performing sixteen (16) 128_ IFFTs at the transmitter (at the condition of four virtual bits). Figure 5 illustrates the power spectral density of an OFDM signal generated using a 〇FDM transmission system in accordance with various embodiments. In Figure 5, the out-of-band power after the nonlinear power amplifier is evaluated by measuring the power spectral density (PSD) of the distorted transmitted signal. To simulate a nonlinear power amplifier, the following AM/AM conversion model is used: 132011 .doc -19- 200908599 (5) s(xm) 1 +

|VP Λ2Ρ The second two is the input signal, and the maximum output signal of the power amplifier is oscillating. ^ In these simulations, production is 3. In the case of a 6^ input fallback (post), the proposed type_2 mechanism of Ά=3 can reduce the out-of-band light shot by about 5 dB. For comparison, Figure 5 also shows the simulation results for the (four) mechanism with a cutoff ratio of four (7). We can see that there is no post wave situation.

The next cut greatly increases the out-of-band light shot. For the same adjacent channel interference 2, the pApR mechanism used by the OFDM transmission system 1 imposes less stringent requirements on the IBO of the power amplifier, which means that a greater power efficiency is achieved. Figure 6 compares the bit error rate performance of the 〇fdm system generated using two different OFDM transmission systems. In Figure 6, the BER performance of the mechanism used by the OFDM transmission system 1 using space_time coding is shown. The simulated system has two transmit antennas and one receive antenna. The Alam〇uti mechanism is used to achieve spatial diversity. In this simulation, the channel model is a quasi-static flat fading channel. A nonlinear power amplifier with IB 〇 = 6 dB is used after the OFDM modulator. A hard decision demodulation is performed at the receiver side. The BEr performance of a system using a cutting mechanism with CR = 1.9 is also given for comparison. As can be seen, the type-2 mechanism with the [7,4] Hamming code has a performance gain of about 1 dB relative to the cutting mechanism because the truncation mechanism introduces in-band noise. In short 'in the case of a virtual bit, for each information bit sequence 132011.doc -20- 200908599

= 'The OFDM transmission system can just generate 2" sufficiently different candidate brilliant signals' and choose to transmit with the lowest sigh signal. PAPR reduction is achieved by increasing the complexity at the feeder. At the receiver side, decoding is almost identical to the conventionally encoded OFDM mechanism without pApR reduction. The most important $' does not exist due to error propagation of any side information detection errors. Because the base station always has A powerful digital signal processor, so this mechanism is especially suitable for the downlink of the coded OFDM system. In addition, it can be easily integrated into the space-time coded OFDM system, especially in the orthogonal space _ The time block code is deployed in the 0FDM system to achieve spatial diversity, and the whirling code is used to achieve frequency diversity X to improve the performance. It should be understood that this mechanism can be extended to have the #他频道码和经$ A system of inter-time coding mechanisms such as 'turbo code and space·time trellis code. Although preferred embodiments are disclosed herein, there may be many variations within the concepts and scope of the present invention. The present invention will be understood by those skilled in the art after reviewing the specification, the drawings and the scope of the patent application. Therefore, the present invention is limited only by the spirit and scope of the accompanying claims. Figure 1 is a block diagram of an embodiment of an embodiment of an orthogonal frequency division multiplexing (OFDM) transmission system. Figure 2 is a diagram of an embodiment of a virtual bit inserter that can be used in the OFDM transmission system of Figure 1. Figure 3 is a functional block diagram of one embodiment of an OFDM data receiver. Figure 4 depicts the peak-to-average power of a 13201Ldoc-21-200908599 OFDM signal generated using a 〇FE) VI transmission system in accordance with various embodiments. Figure 5 illustrates the power spectral density of an OFDM signal generated using an OFDM transmission system in accordance with various embodiments. Figure 6 compares the bit error rate performance of an OFDM system generated using two different OFDM transmission systems. Main component symbol description] 11 Hamming decoder 100 orthogonal frequency division multiplexing (OFDM) transmission system 110-/OFDM signal generator 112 virtual bit inserter 114 recursive cyclocoder 116 bit Element Interleaver 118 OFDM Modulator 120 Signal Selector 130 Transmitter 132 Orthogonal Space-Time Block Encoder (OSTBC) 134 Antenna System 140 Symbol Mapper 150 Time Domain Converter / IFFT 200 Virtual Bit Insert 210 Hamming Encoder 220 bit flipper 300 data receiver 3 10 antenna system 132011.doc -22- 200908599 320 orthogonal frequency division multiplexing (OFDM) demodulator 322-1 first frequency domain converter 322-2 second Frequency Domain Converter 324 Orthogonal Space-Time Block Coding (OSTBC) Decoder 326 OFDM Symbol to Bit Converter or Demapper 330 Deinterleaver 340 Cyclotron Decoder 350 Virtual Bit Removal Benefit 132011.doc •23 ·

Claims (1)

200908599 X. Patent Application Range: 1 · A method for transmitting data, comprising: generating (11〇-Z) a plurality of candidate orthogonal frequency division multiplexing (OFDM) signals, wherein each of the candidate 〇FDM signals is generated One includes: inserting (112, 2〇〇) a set of one or more dummy bits before the data bit sequence to generate an input bit sequence, recursively returning to the % code (114) the input bit sequence to generate An encoded bit sequence, interleaving (116) the encoded bit sequence, OFDM modulating (11 8) the interleaved encoded bit sequence to generate the candidate OFDM signal; selecting (120) having a One of the plurality of candidate OFDM signals having a lowest peak-to-average power ratio; and transmitting (130) the selected 〇fdm signal, wherein the set of one or more virtual bits of each of the candidate OFDM signals This 袓j ' ' or multiple virtual bits 7L are different from each of the other candidate OFDM signals. 2. The method of claim 1 wherein the data bit sequence comprises 2 bits, and wherein the set of one or more dummy bits is inserted (2〇〇) before the data bit sequence to generate the input bit The meta-sequence includes: applying a first group of X bits of one of the data bit sequences to a Hamming encoder (2 1 〇) to generate a Hamming-encoded bit sequence; flipping (220) The sequence of the Hamming coded sequence, 132011.doc 200908599, to output the input bit sequence υ /r force <a group of bits; and rotate the data bit sequence 篦 _ ^ first group Forming a bit as a second set of bits of the input bit sequence, wherein one of the sequences of the Hamming code that is flipped over is inverted for the parent of the candidate OFDM 现The element is different from one of the Hamming-coded sequences of each of the other candidate OFDM signals. 3. The method of </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> <RTIgt; The bit sequence maps 〇4〇) to a plurality of OFDM symbols; and transforms (15〇) the OFDM symbols into a time domain to generate the 〇FDM signal. 4. The method of claim 1 wherein the selected OFDM signal comprises orthogonal space-time block coding (〇STBC) (1 32) the 〇fdm signal and applying the OSTBC signal to an empty Rolling diversity transfer system (134). 5. A system for transmitting data (1〇〇), comprising: a plurality of candidate orthogonal frequency division multiplexing (OFDM) signal generators (11 〇 _ 0, each containing, a dummy bit insertion And (112, 200) adapted to insert a set of one or more dummy bits before a sequence of data bits to generate an input bit sequence, a recursive cyclocoder (114) adapted to receive The input bit sequence is generated and an encoded bit sequence is generated, 132011.doc 200908599 an interleaver (116) adapted to interleave the encoded bit sequence, an OFDM modulator (118) Adapting to receive the interleaved encoded bit sequence and generating a candidate 〇 FDm signal; a signal selector (120) adapted to select the plurality of candidate OFDM signals having a lowest peak-to-average power ratio And a transmitter (1 30) adapted to transmit the selected 〇FDM signal, wherein the candidate OFDM signal generators (1 1 〇 〇 的 of the group of one or more Virtual bit and other candidate 〇FDM signal generators (1 The set of one or more virtual bits of each of 1 0-Z) is different. 6. The system (100) of claim 5, wherein each virtual bit inserter (2〇〇) comprises: a Hamming encoder (210) adapted to receive a first group of bits of the data bit sequence and to generate a Hamming-coded bit sequence; and to position the flip-bit (22〇) To flip a bit of the Hamming coded sequence, wherein the first row of bits of the input bit sequence is rotated to be rotated; wherein each of the candidate 〇FDM signals is flipped One of the sequences of the Hamming coded sequence is different from one of the sequences of the Hamming 35 stone horse that each of the other candidate magnolia signals is flipped. 7. The system of claim 5 ( 1〇〇), wherein the 〇FDM modulator (1)8) includes a 132011.doc 200908599 ~ OFDM symbol mapper (140) adapted to map the interleaved encoded bit sequence to a plurality of 〇FDm a symbol; and a converter (1 50) that are adapted to transform the 〇Fdm symbols into the time domain to produce the OFDM 8. The system of claim 5, wherein the transmitter (130) comprises an orthogonal two-interval block encoder (OSTBC) (l 32) and a spatial diversity transmission system (134) 9. A data receiver (300) comprising: an Orthodox Division Frequency Division Multiplexing (OFDM) demodulation transformer (32A) adapted to receive an OFDM signal and output an interlaced encoded a bit sequence deinterleaver (330) adapted to receive the interleaved encoded bit sequence and output an encoded bit sequence; a cyclocoder (340) adapted to decode the sequence Encoded bit sequence and rotates an output bit sequence; and a virtual bit remover (350) adapted to derive from the output bit Data bit order The value of multiple virtual bits. The virtual bit remover is beneficial to the group to be removed — or An output demapper (326)' wherein the OFDM demodulator is used to demap the frequency domain converter 132011.doc