TWI666886B - Transmitting device, receiving device, and method applicable in an orthogonal frequency division multiplexing-code division multiple access system - Google Patents

Abstract

This case discloses an orthogonal frequency division multiplexing code multiple access system. The system includes a transmitter and a receiver. At the transmitter, an extension and subcarrier mapping unit expands the input data symbol with a compound quadrature sequence (SCQS) code to generate a plurality of chirp signals, and maps each chirp signal to one of the plurality of subcarriers. Inverse discrete Fourier transform is performed on the chirp signal mapped to the subcarrier, and the cyclic prefix (CP) is inserted into the orthogonal frequency division multiplex frame. A parallel-to-serial (P / S) converter converts time-domain data into a serial data stream for transmission. At the receiver, a serial-to-parallel (S / P) converter can convert the received data into a plurality of received data streams, and remove the cyclic prefix from the received data. Perform discrete Fourier transform and equalization on the received data. The despreader can despread the output of the equalizer to recover the transmitted data.

Description

Transmission device, receiving device and method applied in orthogonal frequency division multiplexing division code multiple access system

The present invention relates to a wireless communication system. More particularly, the present invention relates to an orthogonal frequency division multiplexing (OFDM) division code multiple access (CDMA) communication system.

In the future, wireless communication networks will provide broadband services for users' wireless Internet access. These broadband services require reliable and high-rate communications with limited frequency spectrum and inter-symbol interference (ISI) time-sharing (frequency-selective) channels produced by multiple fading. Orthogonal frequency division multiplexing is one of the most promising solutions for several reasons. The orthogonal frequency division multi-tool has high spectral efficiency, and adaptive coding and modulation can be used across subcarriers. The implementation is simplified because baseband modulation and demodulation can be performed using simple circuits such as an inverse fast Fourier transform (IFFT) circuit and a fast Fourier transform (FFT) circuit. Because only one tap equalizer is sufficient to provide superior robustness in a multiplexed environment, a simple receiver structure is one of the advantages of an orthogonal frequency division multiplexing system. In other cases, When the signal extension is used in combination with multiple carriers, a more advanced equalizer is required.

Orthogonal frequency division multiplexing has been adopted by several standards, such as Digital Audio Broadcasting (DAB), Digital Audio Broadcasting Terrestrial (DAB-T), IEEE 802.11a / g, IEEE 802.16 and Asymmetric Digital Subscriber Line (ADSL). Orthogonal frequency division multiplexing systems are considered for use in the long-term evolution of the Wideband Division Code Multiple Access (WCDMA) such as the 3rd Generation Partnership Project (3GPP), Division Multiple Access 2000, Fourth Generation (4G) wireless systems, IEEE 802.11n, IEEE 802.16 and IEEE 802.20.

Despite all the advantages, the orthogonal frequency division multiplexing system has several disadvantages. One of the major disadvantages of orthogonal frequency division multiplexing is its inherent high peak-to-average power ratio (PAPR). As the number of subcarriers increases, the peak-to-average power ratio of the orthogonal division multiplexing also increases. When high peak-to-average power ratio signals are transmitted via a non-linear power amplifier, severe signal distortion occurs. Therefore, the orthogonal frequency division multiplexing system requires a highly linear power amplifier with power backoff. As a result, the power efficiency with orthogonal frequency division multiplexing is very low and the battery life of mobile devices implementing orthogonal frequency division multiplexing is limited.

Techniques for reducing the peak-to-average power ratio of an orthogonal frequency division multiplexed system have been extensively studied. These peak-to-average power ratio techniques include encoding, clipping, and filtering. These methods are different in their effectiveness, and each has its own inherent permutation of complexity, efficiency, and spectral efficiency.

The present invention relates to an orthogonal frequency division multiple division code multiple access system. The department The system includes a transmitter and a receiver. At the transmitter, the extension and subcarrier mapping unit can expand the compound quadrature sequence (SCQS) code to expand the input data symbols to generate a plurality of chirp signals, and map each chirp signal to one of the plurality of subcarriers. Inverse Discrete Fourier Transform (IDFT) or Inverse Fast Fourier Transform Unit can perform inverse discrete Fourier transform or inverse fast Fourier transform on the chirp signal mapped to the sub-carrier, and the loop The prefix (CP) is inserted into the orthogonal frequency division multiplex frame. A parallel-to-serial (P / S) converter converts time-domain data into a serial data stream. At the receiver, a serial-to-parallel (S / P) converter can convert the received data into a plurality of received data streams, and the cyclic prefix is removed from the received data. The discrete Fourier transform (DFT) or fast Fourier transform unit can perform discrete Fourier transform or fast Fourier transform and perform equalization on the received data. The despreader can despread the equalizer output to recover the transmitted data.

110, 510, 610‧‧‧ transmitter

112‧‧‧Spreader

123‧‧‧ Information

124‧‧‧ mixer

150, 550, 650‧‧‧ receivers

151, 551, 651‧‧‧ conjugate

165‧‧‧output

611‧‧‧Time domain spreading code

662‧‧‧Time-Frequency Lake Combiner

804‧‧‧Despreader

812‧‧‧multiplier

c _i ‧‧‧ extended compound quadratic serial code

CP‧‧‧ Cyclic prefix

DFT‧‧‧ Discrete Fourier Transformation

IDFT‧‧‧ Inverse Discrete Fourier Transform

OFDM‧‧‧ Orthogonal Frequency Division Multiplexing

P / S‧‧‧ side by side

SCQS‧‧‧Extended Compound Quadratic Sequence

SF‧‧‧Expansion factor

S / P‧‧‧ Tandem Pair

The present invention can be understood in more detail from the following preferred embodiments in conjunction with the description of the accompanying drawings, in which: FIG. 1 is a block diagram of an orthogonal frequency division multiplexing division multiple access system according to an embodiment of the present invention; FIG. 2 shows The encoding group of the extended composite secondary sequence code according to the present invention; Fig. 3 shows the extension and subcarrier mapping in the system of Fig. 1; Fig. 4 shows the alternative explanation of the extension and subcarrier mapping in the system of Fig. 1; FIG. 5 is a block diagram of an orthogonal frequency division multiplexing division multiple access system according to another embodiment of the present invention; FIG. 6 is an orthogonal frequency division multiplexing division multiple access system according to another embodiment of the present invention; Take a system block diagram; FIG. 7 shows an alternative method of frequency domain extension and subcarrier mapping in the system of FIG. 6; and FIG. 8 shows an example block diagram of a time-frequency Rake combiner according to the present invention.

The invention can be applied to wireless communication systems that implement orthogonal frequency division multiplexing and code division multiple access, such as IEEE 802.11, IEEE 802.16, long-term evolution third-generation (3G) honeycomb systems, and fourth-generation (4G) systems, Satellite system, digital sound broadcasting, digital video broadcasting (DVB) or the like.

The features of the present invention can be incorporated into integrated circuits (ICs) or configured in circuits that include multiple interconnect components.

The invention can provide an orthogonal frequency division multiplexing-dividing code multiple access system with improved peak-to-average power ratio and capacity. The invention uses a special spreading code and a compound secondary sequence code to expand the input data symbols. The extended composite secondary sequence code includes two components: a secondary phase sequence code and an orthogonal (or pseudo-orthogonal) spreading code. Examples of secondary phase sequence codes marked by G are Newman phase codes (or polyphase codes), generalized loop sequences (GCL), and Zadoff-Chu sequences. The secondary phase sequence is also called a polyphase sequence.

In order to support the variable spreading factor (VSF), the sequence length of the quadratic phase sequence (or polyphase sequence) is limited to K = 2 ^k . In some special cases (such as random access channels or on-chain references), the sequence length of the secondary phase sequence (or polyphase sequence) can be any arbitrary integer. Given this carrier number N = 2 ^{n in the system} , consider the N sequence length as N. Next, the general Newman phase code sequence is fixed. The general Newman phase code sequence is:

More orthogonal Newman phase code sequences are created by transforming the general Newman phase code sequence. The first conversion version (or discrete Fourier transform modulation) of the general Newman phase code sequence is:

The two Newman phase code sequences with different transitions are orthogonal to each other.

An example of the orthogonal (pseudo-orthogonal) spreading code marked by H is the Walsh-Hadamard code, which is given as:

Spreading compound secondary sequence codes are constructed by combining quadratic phase codes and orthogonal (pseudo-orthogonal) spreading codes. For a specific spreading factor of 2 ^m , the extended composite secondary sequence code has a 2 ^m chirp signal. The general secondary phase sequence code part of the extended compound secondary sequence code has a 2 ^m chirp signal, which is:

Where k = 0, 1, ..., 2 ^m -1, i = 0, 1, ..., 2 ^nm -1. The first transformed version of the quadratic phase sequence code part has a 2 ^m chirp signal, which is:

Among them, 1 = 0, 1, ..., N-1, k = 0, 1, ..., 2 ^m -1, i = 0, 1, ..., 2 ^nm -1.

For a specific extended compound secondary sequence code with a spreading factor of 2 ^m , the orthogonal (pseudo-orthogonal) spreading code part of the extended compound secondary sequence code is an orthogonal (pseudo-orthogonal) spreading code group with a spreading factor of 2 ^m . One of the encodings is given. For example, the h-th encoding is marked (h, :).

Expansion of the second composite sequence code k c _i number of voice-based pumping is constructed as a first transformed version ships Newman phase code sequences of k-sequence code and a quadratic phase with N = 2 ^m of the size of the orthogonal h (Pseudo The product of the kth sound signal of the orthogonal) spreading code.

The encoding group size of the extended composite secondary sequence code is determined by the encoding group size of the orthogonal (pseudo-orthogonal) extension code portion and the secondary phase sequence code portion. Regardless of the spreading factor, the encoding group size of the secondary phase sequence code is fixed and determined by the different number of conversions of the system's subcarriers 2 ⁿ . The encoding group size of orthogonal (pseudo-orthogonal) spreading codes depends on the spreading factor. For example, in the Walsh-Hadamard code example, the size is equal to the expansion factor 2 ^m (0 m n).

Different users are assigned different extended compound secondary sequence codes. In order for the receiver to distinguish different users, the quadratic phase sequence code part, orthogonal (false Orthogonal) spreading code part or the spreading compound secondary sequence code used by the two users is different. The encoding group of the extended composite secondary sequence code is shown in FIG. 2. When there is no multiplexing, as long as the secondary phase sequence code parts are different, different extended composite secondary sequence codes are orthogonal; or orthogonal spreading codes are used. Different extended composite secondary sequence codes are pseudo-orthogonal only if their secondary phase sequence code portions are the same and a pseudo-orthogonal spreading code is used. In both cases, the multiple access interference (MAI) between different codes is zero or very small.

In a multi-path fading environment, the codes assigned to different users should make the difference in the transformation of the secondary phase sequence code part as large as possible. The codes assigned to different users should not cause any multiple access interference between the two codes if the difference in the transformation of the two-phase sequence code part of the two codes is not less than the maximum delay spread of the multiple channels. Therefore, the corresponding orthogonal (pseudo-orthogonal) spreading code portions can be assigned the same. Alternatively, the difference in the transformation of the part of the secondary phase sequence code may be limited to the maximum delay spread of the multiple channels. This can create more coding with full multiple access interference immunity. This can be achieved as long as the number of users in the system is only N / L, where N is the number of subcarriers and L is the maximum delay spread of the multiple channels.

If the difference in the transformation of the two-phase sequence codes of the two codes is smaller than the maximum delay spread of the multiple channels, the corresponding orthogonal (pseudo-orthogonal) spreading code sections should be different to reduce the Multiple access interference.

In this method, because the phase relationship between orthogonal codes is further reduced by the correlation of the two-phase phase sequence code, the multiple access interference can be reduced compared with the conventional coded multiple access system. For interference limiting systems (e.g. Code multiple access), multiple access interference reduction means increased system capacity.

The orthogonal frequency division multiplexing-code division multiple access system of the present invention includes a transmitter and a receiver. The transmitter includes an extension and subcarrier mapping unit and an orthogonal frequency division multiplexing unit. The extension and subcarrier mapping component can expand the input data symbol into a plurality of chirp signals and map the chirp signals to one of the plurality of subcarriers. The orthogonal frequency division multiplexing unit can perform conventional orthogonal frequency division multiplexing operations. This extension can be performed in the frequency domain, time domain or both, which will be explained in detail as follows.

FIG. 1 is a block diagram of an orthogonal frequency division multiplex division code multiple access system 100 according to a first embodiment of the present invention. The system 100 includes a transmitter 110 and a receiver 150. The transmitter 110 includes a spreader 112, a serial-to-parallel (S / P) converter 114, a primary carrier mapping unit 116, an inverse discrete Fourier transform unit 118, and a cyclic prefix (CP) insertion. The unit 120 includes a parallel-to-serial (P / S) converter 122 and an optional mixer 124. The spreader 112 may use the extended composite secondary sequence code 111 to expand the input data symbol 101 in the frequency domain. The procedures for extension and subcarrier mapping are shown in Figure 3. The spreading factor used to extend the compound quadratic sequence code c _i is 2 ^m (0 m n). One user can use all 2 ⁿ carriers in the system. Therefore, the number of data symbols that can be transmitted by a user in an orthogonal frequency division multiplex frame is 2 ^nm . Each data symbol d (i) 101 by spreading code based c _i 111 extended to 2 ^m 113.2 ^m jack voice number 113, followed by pumping voice parallel to serial converter 114 is converted into parallel pumping voice No. 2 ^m 115, and each chirp signal is mapped equidistantly to one of the subcarriers 117 by the subcarrier mapping unit 116. The distance between sub-carriers used for the chirp signal of the same data symbol is the 2 ^nm sub-carrier. The chirp signals of different data symbols are sequentially mapped to the subcarriers in the system, so that the chirp signals of the data symbol d (i) can be mapped to the subcarriers 2 ^nm ‧k + i, (k = 0, 1, ..., 2 ^m -1, i = 0, 1, ..., 2 ^nm -1).

Figure 4 shows an alternative embodiment of extension and sub-carrier mapping. The repeater 402 is used in place of the spreader 112 to repeat each data symbol d (i) 2 ^m times at a chirp signal rate. The repeated data symbol 404 is converted into a 2 ^m parallel symbol 407 by a serial-to-parallel converter 406, and each symbol is sequentially and equidistantly mapped to one of the 2 ^m sub-carriers by a sub-carrier mapping and weighting unit 408. . The distance between each subcarrier is 2 ^nm subcarrier. The chirp signals of different data symbols are sequentially mapped to the subcarriers in the system, so that the chirp signals of the data symbol d (i) can be mapped to the subcarriers 2 ^nm . k + i, (k = 0, 1, ..., 2 ^m -1, i = 0, 1, ..., 2 ^nm -1). Is mapped to 2 ^{nm for} each subcarrier. The sign of k + i is to make the subcarrier 2 ^{nm by} weighting the extended compound quadratic sequence code. The symbol on k + i is multiplied and marked as The k-th sound signal of the extended composite secondary sequence code.

Referring back to FIG. 1, the chirp signal 117 mapped on the subcarrier is fed into the inverse discrete Fourier transform unit 118 and converted into time domain data 119. The cyclic prefix is then added to each orthogonal frequency division multiplex frame end by the cyclic prefix insertion unit 120. The time domain data 121 with a cyclic prefix is then converted into serial data 123 by a parallel-to-serial converter 122 and transmitted on a wireless channel. It should be noted that the inverse discrete Fourier transform operation can be replaced by an inverse fast Fourier transform or other similar operation. The cyclic prefix insertion can be used in the inverse discrete Fourier transform output by a side-to-side converter. 122 is performed before conversion to serial data, and cyclic prefix removal may be performed before the received signal is converted into a parallel data stream by the serial-to-parallel converter 154.

Due to the structure of the extended data, the inverse discrete Fourier transform operation system can be simplified. The output 119 of the inverse discrete Fourier transform unit 118 can be transformed by a specific phase. This bit is a function corresponding to the input data subcarrier and data symbol index. Therefore, the inverse discrete Fourier transform operation can be replaced by a phase transform calculation that does not require much calculation.

For example, suppose n / 2 <m n and the orthogonal (pseudo-orthogonal) spreading code part of the extended compound quadratic sequence code is {1,1, ..., 1}. The h-th output of the inverse discrete Fourier transform unit 118 is given as follows:

The value of h satisfies the following conditions: h = 2 ^nm ‧p + i, p = 0,1, ... 2 ^m -1, i = 0,1, ..., 2 ^nm -1

The masking operation may be performed at the transmitter 110 and the corresponding unmasking operation may be performed at the receiver 150. The purpose of the mask is to reduce multiple access interference between cells. At the transmitter 110, the mixer 124 may multiply the data 123 by the mask code 125 before transmitting. The corresponding unmasking operation is performed at the receiver 150. The mixer 152 may multiply the received signal 128 by the conjugate 151 of the mask code 125 to generate a demasked data stream 153.

Referring to FIG. 1, the receiver 150 includes an optional mixer 152, a serial-to-parallel converter 154, a cyclic prefix removal unit 156, a discrete Fourier conversion unit 158, an equalizer 160 and A solution spreader (including Contains a multiplier 162, an adder 164, and a scaler 166). The time-domain received data 128 is converted into a parallel data stream by a serial-to-parallel converter 154, and the cyclic prefix is removed by a cyclic prefix removing unit 156. These operational efficiencies can be exchanged as explained above. The output 157 from the cyclic prefix removal unit 156 is then fed into a discrete Fourier transform unit 158 to be converted into frequency domain data 159. The equalization of the frequency domain data 159 is performed by the equalizer 160. For example, in a traditional orthogonal frequency division multiplexing system, a simple one-point equalizer can be used for frequency domain data 159 at each subcarrier. It should be noted that the discrete Fourier transform operation may be replaced by a fast Fourier transform operation or other similar operations.

Due to the extended data structure, the discrete Fourier transform operation can also be simplified. The output 159 of the discrete Fourier transform unit is a data symbol transformed by a specific phase. The phase is a function corresponding to the input data subcarrier and data symbol index. Therefore, the discrete Fourier transform operation can be replaced by a phase transform calculation that does not require much calculation. This is done in a similar way but in contrast to the inverse discrete Fourier transform at the opposite transmitter side.

The equalized data are despread and spread in the frequency domain. After equalization, the output 161 at each subcarrier is multiplied by a multiplier 162 by the extended compound secondary sequence code used at the transmitter 110. ， K = 0，1 ， ... ， 2 ^m -1 corresponding to the conjugate 168 of the chirp signal. Next, the multiplication output 163 at all subcarriers is summed by the adder 164, and the summed output 165 is normalized by the ruler 166 with an expansion factor of the extended composite secondary sequence code to recover the data 167.

The receiver 150 may further include a block linear equalizer or a joint detector (not shown) that can process the despreader output. Any type of block linear equalizer or joint detector can be used. One of the traditional configurations of the block linear equalizer or joint detector is a minimum mean square error (MMSE) block linear equalizer. In this example, the channel matrix H is established and calculated for the subcarriers, and the equalization system uses the established channel matrix to perform:

Where H is the channel matrix, Is the received signal in the subcarrier, Is the equalized data vector in the subcarrier.

For the on-chain operation, it is better to maintain a fixed envelope after the inverse discrete Fourier transform operation, which promotes the use of efficient and inexpensive power amplifiers. To maintain a fixed envelope, the following conditions must be met for a system with N = 2 ^n- th carrier. First, the expansion factor of 2 ^m is m n limit, where a The term means the smallest integer greater than a. Secondly, for the spreading factor of 2 ^m , only part of the orthogonal codes are used to combine the secondary phase sequence codes to generate an extended composite secondary sequence code that can obtain a fixed envelope. For example, in the Newman phase code and Hadamard code examples, only the first Hadamard code group Codes (2 ^{m in} size) are used in combination with Newman phase sequence codes to generate extended composite quadratic sequence codes. b The term means the largest integer less than b.

As mentioned above, as long as the number of users in the system does not exceed N / L, there is no multiple access interference and no multi-user detection (MUD) is required. When the number of users in the system exceeds N / L, there will be multiple access interferences and multi-user detection may be implemented. Multiple access interference is better than traditional coded multiple access systems with the same number of users.

Suppose there are M users in the system. Then the number of users detected by the multi-user in the conventional coded multiple access system will be M. However, the number of users detected by multiple users in the conventional CDMA multiple access system according to the present invention will be M / L Compared with the traditional code division multiple access system, the L metric is reduced. In this way, the complexity of the multi-user detection operation is much lower than the multi-user detection in the prior art conventional coded multiple access system. Multiple antennas at the transmitter and / or receiver can also be used.

FIG. 5 is a block diagram of an orthogonal frequency division multiplexing division multiple access system 500 (multi-carrier direct sequence (MC-DS) division multiple access system) according to another embodiment of the present invention. The system 500 includes a transmitter 510 and a receiver 550. The transmitter 510 includes a serial-to-parallel converter 512, a plurality of multipliers 514, a primary carrier mapping unit 516, an inverse discrete Fourier transform unit 518, a parallel-to-serial converter 520, and a cyclic prefix. Insertion unit 522, and an optional mixer 524. If the system 500 has N = 2 ⁿ carriers, the N consecutive data symbols 501 of user i are converted from serial to N parallel symbols 513 by a serial-to-parallel converter 512. The jth data symbol of the N parallel data symbol 513 of the user i is labeled as d ^j (i), where j = 0, 1, ..., N-1. The extended compound secondary sequence code used by user i is labeled as c _i . Each N-parallel data symbol 513 is extended in the time domain using an extended composite quadratic sequence code c _i 511. The spreading factor of the extended compound quadratic sequence code c _i is 2 ^m (0 m n). Therefore, each data symbol 513 is extended to a 2 ^m chirp signal 515 by expanding the compound secondary sequence code c _i 511.

During the duration of each chirp signal, one chirp signal of each N data symbol d ^j (i) is transmitted on its corresponding subcarrier j. One user can use all 2 ⁿ carriers in the system. Therefore, the number of data symbols that can be transmitted by a user in an orthogonal frequency division multiplex frame is 2 ⁿ .

The chirp signal 515 is equally mapped to the subcarrier by the subcarrier mapping unit 516. The chirp signal 517 on the subcarrier is fed into the inverse discrete Fourier transform unit 518 and converted into time domain data 519. The time-domain data 519 is converted from parallel to serial data 521 by a parallel-to-serial converter 520, and a cyclic prefix is added to each frame end by a cyclic prefix insertion unit 522. The data 523 with a cyclic prefix is transmitted on a wireless channel. Similarly, the extended composite secondary sequence code is used to perform a conventional direct sequence code division multiple access operation on each subcarrier, and the direct sequence code division multiple access signal on the subcarrier is transmitted in parallel using an orthogonal frequency division multiplexing structure.

The receiver 550 includes a cyclic prefix removal unit 554, a serial-to-parallel converter 556, a discrete Fourier transform unit 558, an equalizer 560, a plurality of Rake combiners 562, and a parallel-to-parallel Column converter 564. First, the cyclic prefix is removed from the received data 528 via the wireless channel by the cyclic prefix removing unit 554. The data 555 is then converted from the serial to the parallel data 557 by a serial-to-parallel converter 556. The parallel data 557 is then fed into the discrete Fourier transform unit 558 and converted into frequency domain data 559. Then, the frequency domain data 559 is equalized by the equalizer 560. For example, in a traditional orthogonal frequency division multiplexing system, a simple one-point equalizer can be used at each carrier.

The data 561 on each carrier after equalization is recovered in the time domain by the RAKE combiner 562 (including the despreader). The parallel data symbols 563 generated by each RAKE combiner 562 are parallel-paired by a parallel-to-serial converter 564 Serial conversion to recover the transmitted data.

As in the first embodiment of FIG. 1, a masking operation can be performed at the transmitter 510 and a corresponding demasking operation can be performed at the receiver 550 to reduce multiple access interference between cells. The mixer 524 may multiply the output 523 from the cyclic prefix insertion unit 522 by the mask code 525 before transmitting. The mixer 552 of the receiver 550 may multiply the received signal 528 by the conjugate 551 of the mask code 525 used at the transmitter 510.

FIG. 6 is a block diagram of an orthogonal frequency division multiplexing division multiple access system 600 according to a third embodiment of the present invention. The system 600 includes a transmitter 610 and a receiver 650. The transmitter 610 includes a serial-to-parallel converter 612, a plurality of multipliers 614, a plurality of repeaters 616, a plurality of serial-to-parallel converters 618, a carrier mapping and weighting unit 620, and a reverse discrete richer A leaf conversion unit 622, a parallel-to-serial converter 624, a cyclic prefix insertion unit 626, and an optional mixer 628. According to the third embodiment, the input data symbols are expanded twice, once in the time domain and once in the frequency domain. Assume that the total number of subcarriers is 2 ⁿ , and the expansion factors used for time domain and frequency domain extension are 2 ^p and 2 ^{m, respectively} . The user i N _T consecutive data symbol 601 by lines parallel to serial converter 612 is converted from serial to parallel N _T symbol 613. The N _T value is equal to 2 ^nm . The j-th data symbol of the N _T parallel data symbol 613 of the user i is labeled as d ^j (i), where j = 0, 1, ..., N-1. The time domain extension code 611 used by user i is marked as (i, :). Each N _T parallel data symbol 613 then multiplies the symbol 613 by a time domain spreading code by a multiplier 614 (i, :) 611 is extended in the time domain. Time domain spreading code The expansion factor of (i, :) is 2 ^p defined in equations (3) and (4). Each data symbol 613 is extended based voice jack No. 2 ^p, and 2 ^p N _T parallel pumping voice stream number 615 is generated.

After the time domain expansion, the frequency domain expansion system is performed. For each jack voice stream number j (corresponding to the j-th data symbol of the N _T data symbol), the given user i, N _T jack system each jack voice number of the voice stream number is repeated to continuously during each pumping voice number 616 repeats 2 ^m times, the sound signal which is repeated 2 ^m times is converted into a parallel 2 ^m sound signal 619 by a serial-to-parallel converter 618. The 2 ^m chirp signal is then sequentially mapped to a 2 ^m equidistant sub-carrier by a sub-carrier mapping and weighting unit 620. The distance between each subcarrier is 2 ^nm subcarrier. The sub-carrier mapping is performed sequentially so that the repeated sound signal from the j-th sound signal stream is mapped to the sub-carrier 2 ^nm ‧k + j, (k = 0, 1, ..., 2 ^m -1 , J = 0, 1, ..., 2 ^nm -1). Before the inverse discrete Fourier transform operation, the chirp signal on each carrier 2 ^nm ‧k + j is marked by The k- _th sound signal of the extended composite secondary sequence code c _i is weighted.

One user can use all 2 ⁿ carriers in the system. Therefore, the number of data symbols that can be transmitted by a user in an orthogonal frequency division multiplex frame is 2 ^nm .

Figure 7 shows an alternative method of frequency domain extension and subcarrier mapping in the system of Figure 6. In addition to repeating the chirp signal 2 ^m times, the chirp signal 615 is a frequency domain spreading code. Expand directly. For each jack voice stream number j (corresponding to the j-th data symbol of the N _T data symbol), the given user i, each of the pumping system 615 to voice duration during each pumping voice number multiplier 702 by complex spreading code sequences of secondary 703 is a 2 ^m chirp signal 704, and the frequency domain extended chirp signal 704 is converted into a 2 ^m parallel chirp signal 707 by a serial-to-parallel converter 706. As described above, these parallel chirp signals 707 are then sequentially mapped by the sub-carrier mapping unit 708 to the 2 ^m equidistant sub-carriers 709. The distance between each subcarrier is 2 ^nm subcarrier. The sub-carrier mapping is performed sequentially so that the repeated sound signal from the j-th sound signal stream is mapped to the sub-carrier 2 ^nm ‧k + j, (k = 0, 1, ..., 2 ^m -1 , J = 0, 1, ..., 2 ^nm -1).

Referring again to FIG. 6, the chirp signal 621 mapped on the subcarrier is fed into the inverse discrete Fourier transform unit 622 and is converted into time domain data 623. The time-domain data 623 is converted from the parallel data to the serial data 625 by a parallel-to-serial converter 624, and a cyclic prefix is added to each frame end of the data 625 by a cyclic prefix insertion unit 626. The data 627 with a cyclic prefix is transmitted on a wireless channel.

The receiver 650 includes an optional mixer 652, a cyclic prefix removal unit 654, a serial-to-parallel converter 656, a discrete Fourier transform unit 658, an equalizer 660, and a plurality of time-frequency Rake combiner 662 and a parallel-to-serial converter 664. At the receiver 650 side, the cyclic prefix is removed from the received data 632 through the wireless channel by the cyclic prefix removing unit 654. The data 655 is then converted from the serial to the parallel data 657 by a serial-to-parallel converter 656. The parallel data 657 is fed to the discrete Fourier transform unit 658 and converted into frequency domain data 659. Then, the frequency domain data 659 is equalized by the equalizer 660. For example, in the traditional orthogonal frequency division multiplexing system, a simple one-point equalizer can be used at each subcarrier.

After equalization, the data 661 on each subcarrier is recovered by the time-frequency Rake combiner 662, which will be explained in detail as follows. Time-frequency The parallel data symbol 663 generated by the rate rake combiner 662 is then parallel-to-serial converted by the parallel-to-serial converter 664 to recover the transmitted data.

The time-frequency RAKE combiner 662 is a RAKE combiner that can process time and frequency domain recovery at the transmitter and is extended in the time and frequency domain. Figure 8 shows 662 examples of the Laker combiner. Those skilled in the art should note that the time-frequency RAKE combiner 662 can be implemented in many different ways, and the configuration shown in Figure 8 is provided as an example and not a limitation. Each time-frequency RAKE combiner 662 includes a primary carrier grouping unit 802, a despreading spreader 804, and a RAKE combiner 806. For each data symbol j (j = 0, 1, ..., 2 ^nm -1) of the _NT continuous data symbol, the sub-carrier grouping unit 802 can collect the snoring signal 661 2 ^nm on the following sub-carriers. k + j, a total of 2 ^m sound signals. Then, the despreader 804 may perform frequency domain despreading on the chirp signal on the 2 ^m- th carrier. The despreader 804 includes a plurality of multipliers 812 that can multiply the conjugate 813 of the extended composite quadratic sequence code by the collected chirp signal 811, and can add up one of the multiplier outputs 814 to an adder 815, which is normal. One of the rulers 817 of the summed output 816. After despreading in the frequency domain, the chirp signal on the 2 ^n- th carrier becomes the chirp signal 818 on the _TT parallel chirp signal stream. In order to restore the j-th data symbol of user i, the time-domain Rake combination is performed on the corresponding chirp signal stream 818 by the Rake combiner 806.

Referring again to FIG. 6, a masking operation can be performed at the transmitter 610 and a corresponding demasking operation can be performed at the receiver 650 to reduce multiple access interference between cells. The mixer 628 can insert The output 627 of the input unit 626 is multiplied by the mask code 630. The mixer 652 of the receiver 650 may multiply the received signal 632 by the conjugate 651 used for the mask code at the transmitter 610.

For all the above embodiments, the predetermined data vector {d (i)} (that is, the prediction signal) may be transmitted. In this method, the uplink transmitted signal can be used as a random access channel (RACH) pilot or an uplink pilot signal. For example, a predetermined data vector {d (i)} of 1, {1,1, ..., 1} can be transmitted.

Although the features and components of the present invention are described in specific embodiments in specific combinations, each feature and component does not require other features and components of the preferred embodiment, or various combinations of other features and components with or without the present invention. Is used alone.

Claims (20)

A device for user equipment (UE) includes: a processor, which is configured to generate a polyphase sequence; and to determine an orthogonal sequence; and an expansion circuit, which is configured to combine an input symbol and the polyphase sequence, and use the positive A cross sequence is used to expand the combined result to obtain a plurality of symbols; and a mapping circuit is configured to map the plurality of symbols to a plurality of subcarriers. The device according to item 1 of the scope of patent application, further comprising: an inverse Fourier transform (IFT) circuit, which is configured to implement IFT on the plurality of symbols mapped to the plurality of subcarriers to obtain time-domain symbols . The device according to item 2 of the patent application scope, wherein the IFT includes at least one of an inverse fast Fourier transform (IFFT) and an inverse discrete Fourier transform (IDFT). The device as described in the second item of the patent application scope further includes: a cyclic prefix (CP) insertion circuit, which is configured to insert CP into such time-domain symbols. The device according to item 1 of the scope of patent application, wherein the processor is configured to generate a general polyphase sequence; and convert the general polyphase sequence, wherein the polyphase sequence is obtained by Generic polyphase sequences are generated by conversion. The device according to item 5 of the patent application scope, wherein the conversion includes a phase conversion of the general polyphase sequence. The device as described in claim 5 of the patent application scope, wherein the conversion includes a discrete Fourier transform (DFT) modulation of the general polyphase sequence. The device according to item 5 of the patent application scope, wherein different transformations of the general polyphase sequence result in different polyphase sequences which are orthogonal to each other. The device according to item 1 of the scope of patent application, wherein the polyphase sequence is at least one of a quadratic phase sequence and a Zadoff-Chu sequence. The device according to item 1 of the scope of patent application, wherein the mapping circuit is configured to sequentially map the plurality of symbols to the plurality of subcarriers. A user equipment (UE) includes: an expansion circuit, which constitutes a combination of input symbols and a polyphase sequence, and uses an orthogonal sequence to expand the combined result to obtain a plurality of symbols; a mapping circuit, which constitutes the plurality of symbols Mapping to a plurality of subcarriers; and an orthogonal frequency division multiplexing (OFDM) transmission receiver, the OFDM transmission receiver includes: an inverse Fourier transform (IFT) circuit, which constitutes a pair of mappings to the plurality of subcarriers Implement the IFT on the plurality of symbols to obtain a time-domain symbol, wherein the IFT is at least one of an inverse fast Fourier transform (IFFT) and an inverse discrete Fourier transform (IDFT); and a cyclic prefix (CP) Insertion circuit, which constitutes the insertion of CP in such time-domain symbols. The UE according to item 11 of the scope of patent application, wherein the UE further comprises a processor, the processor system being configured to: generate a general polyphase sequence; and convert the general polyphase sequence; and generate the multiphase sequence Phase sequence, where the polyphase sequence is derived by transforming the general polyphase sequence. The UE according to item 12 of the patent application scope, wherein the processor system is configured to transform the general polyphase sequence by modulating a discrete Fourier transform (DFT) of the general polyphase sequence. The UE according to item 12 of the scope of patent application, wherein different conversions of the general polyphase sequence result in different polyphase sequences that are orthogonal to each other. The UE according to item 11 of the scope of patent application, wherein the polyphase sequence is a quadratic phase sequence, and wherein the secondary phase sequence is a Zadoff-Chu sequence. The UE according to item 11 of the scope of patent application, wherein the mapping circuit is configured to sequentially map the plurality of symbols to the plurality of subcarriers. A computer-readable medium having instructions stored thereon, which, when executed by a computing device, cause the computing device to: generate a polyphase sequence based on a general polyphase sequence; combine an input symbol and the A polyphase sequence, and using an orthogonal sequence to expand the combined result to obtain a plurality of symbols; and mapping the plurality of symbols to a plurality of subcarriers. The computer-readable medium according to item 17 of the scope of patent application, wherein the polyphase sequence is generated by converting the general polyphase sequence. The computer-readable medium according to item 17 of the scope of patent application, wherein the instructions, when executed by the computing device, further cause the computing device to: generate the orthogonal sequence, wherein the orthogonal sequence It is selected from a set of orthogonal spreading codes. The computer-readable medium as described in item 17 of the scope of patent application, wherein the instructions for mapping the plurality of symbols to the plurality of subcarriers include instructions, and when executed by the computing device, The computing device is caused to: sequentially map the plurality of symbols to the plurality of subcarriers.