CN101536445A - Method of transmitting data in a mobile communicaiton system - Google Patents

Abstract

Disclosed is a data transmission method in a mobile communication system. Said method of data transmission via code sequences in a mobile communication system comprises: grouping an input data stream into a plurality of blocks, said blocks consisting of at least 1 bit, such that each block is mapped to a corresponding signature multiplies the stream of signature sequences to which multiple blocks are mapped by a specific code sequence, and sends the stream of signature sequences multiplied by the specific code sequence to a receiver.

Description

Method for transmitting data in mobile communication system

technical field

The present invention relates to a mobile communication system, and more specifically relates to a method for extending a code sequence, a structure of a random access channel and a method for transmitting data in the mobile communication system.

Background technique

In a state where the user equipment is not uplink-synchronized with the base station, the user equipment uses a random access channel (RACH) to access the network. A signal having repetitive characteristics in the time domain is used in the random access channel so that a receiver can easily search for a start position of a transmission signal. Typically, the repetition property is achieved by the repeated transmission of the preamble.

A representative example of one sequence for realizing the preamble includes a CAZAC (Constant Amplitude Zero Autocorrelation) sequence. The CAZAC sequence is represented by a Dirac-Delta function in the case of autocorrelation and has a constant value in the case of cross-correlation. In this regard, it has been estimated that CAZAC sequences have good transmission characteristics. However, CAZAC sequences have limitations in that a maximum number of N-1 sequences can be used for sequences with length N. For this reason, a method for increasing available bits of a sequence while maintaining good transmission characteristics is required.

Meanwhile, various methods for transmitting data from a random access channel by using a CAZAC sequence are provided. As far as they are concerned, the first method directly interprets the CAZAC sequence ID as message information. Assuming that data to be transmitted is a preamble, if a sufficient amount of sequences usable as preambles is provided, message passing can be performed using only the CAZAC sequence ID without additional operations. However, since a method of transmitting additional information should be considered in the RACH that is actually synchronized, there arises a problem that it is difficult to realize a sufficient amount of CAZAC sequence sets, and the cost required for the search by the receiver increases.

The second method transmits the CAZAC sequence and the Walsh sequence simultaneously by using a code division multiplexing (CDM) method. In this case, the CAZAC sequence ID is used as user equipment identification information, and the Walsh sequence transmitted in the CDM manner is interpreted as message information. Fig. 1 is a schematic block diagram showing a transmitter for implementing the second method. However, the second method has a limitation: even if the Walsh sequence is added to the CAZAC sequence, when the Walsh sequence has length N, only log ₂ N bits of additional information can be obtained.

The third method is to transmit the CAZAC sequence and the Walsh sequence in a manner of mixing the Walsh sequence and the CAZAC sequence. In this case, the CAZAC sequence ID is used as user equipment identification information, and the Walsh sequence is interpreted as message information. Fig. 2 is a block diagram showing a data processing procedure performed at a transmitter for realizing the third method. However, according to the third method, since the sequence ID is difficult to detect because the Walsh sequence acts as noise during the detection of the CAZAC sequence, there is a limitation that a repeated sequence should be transmitted to prevent the Walsh sequence from acting as noise during the detection of the CAZAC sequence.

A fourth method either gives orthogonality between the blocks making up the corresponding sequence by multiplying the exponential term with the CAZAC sequence, or directly applies data modulation, such as DPSK, DQPSK, D8PSK, etc. In this case, the CAZAC sequence ID is used as user equipment identification information, and the modulated sequence is demodulated and then used as message information. FIG. 3A shows data modulation according to the former method of the fourth method, and FIG. 3B shows data modulation according to the latter method of the fourth method.

Also, the fifth method transmits a CAZAC sequence by attaching a message part to the CAZAC sequence. Figure 4A shows the case where a message (encoded bit) is attached to a CAZAC sequence used as a preamble, while Figure 4B shows the case where a message (encoded bit) is attached to a predetermined number of fields given to be orthogonal A sequence of blocks.

However, the fourth method and the fifth method have a problem of being susceptible to channel state changes.

Contents of the invention

Therefore, the present invention is proposed to substantially eliminate one or more problems caused by the limitations and disadvantages of the related art, and an object of the present invention is to provide a method for transmitting and receiving messages between user equipment and base stations by using long sequences. A method to maximize time diversity/frequency diversity and mitigate performance degradation caused by channels.

Another object of the present invention is to provide a method of transmitting data through a code sequence in a mobile communication system, wherein the amount of data can be increased and the transmitted data becomes more robust against noise or channel changes.

Yet another object of the present invention is to provide a method for proposing a structure of an efficient random access channel in a multi-carrier system.

Still another object of the present invention is to provide a method for minimizing the time of a random access channel accessed by a user equipment in a mobile communication system.

To achieve these objects and other advantages and in accordance with the object of the present invention, as embodied and broadly described herein, a method of data transmission via a random access channel in a mobile communication system comprises: generating by multiplying a code sequence with an index sequence new code and transmit the new code sequence to the receiver.

In another aspect of the present invention, a data transmission method performed in a mobile communication system by using a code sequence includes: conjugating at least one element included in at least one block of the code sequence divided into at least two blocks, To indicate the predetermined information, and transmit the code sequence in which at least one block is conjugated to the receiver.

In yet another aspect of the present invention, a data transmission method in a mobile communication system by using code sequences includes: generating a second code sequence indicating predetermined information by combining at least two first code sequences mapped using at least one information bit, respectively. a code sequence, and transmitting the second code sequence to the receiver.

In yet another aspect of the present invention, a code sequence transmission method in a mobile communication system includes: generating a combined code sequence by combining a base code sequence to at least one code sequence obtained through a cyclic shift of the base code sequence, and transmitting the combined code sequence to the receiver.

In yet another aspect of the present invention, the code sequence transmission method in the mobile communication system includes: generating a repeated code sequence by repeating and concatenating the first code sequence at least one or more times, and duplicating a certain part of the back end of the repeated code sequence And cascading the duplicate part to the front end of the repeated code sequence to generate a cyclic prefix (CP), and transmitting the repeated code sequence in which the CP is generated to the receiver.

In yet another aspect of the present invention, the method for assigning a random access channel (RACH) in a multi-carrier system includes: so that the frequency bands (frequency bands) of the random access channels assigned to at least two adjacent frames do not overlap each other The method allocates a random access channel to each of at least two adjacent frames, and transmits allocation information of the random access channel allocated to the at least two adjacent frames to at least one user equipment.

In yet another aspect of the present invention, a data transmission method via a code sequence in a mobile communication system includes: respectively mapping each of a plurality of blocks having at least 1 bit of an input data stream to a corresponding signature sequence, The signature sequence stream to which the plurality of blocks are mapped is multiplied by the specific code sequence, and the signature sequence stream multiplied by the specific code sequence is transmitted to the receiver.

Description of drawings

1 shows an example of a method of data transmission through a random access channel in an OFDMA system according to the related art;

FIG. 2 shows another example of a method for data transmission through a random access channel in an OFDMA system according to the related art;

3A and 3B show another example of a method of data transmission through a random access channel in an OFDMA system according to the related art;

4A and 4B show another example of a method for data transmission through a random access channel in an OFDMA system according to the related art;

Figure 5 shows an example of the structure of a random access channel used in an OFDMA system;

FIG. 6A and FIG. 6B show examples of sending RACH signals in the time domain or frequency domain based on the structure of the random access channel in FIG. 5;

FIG. 7 shows another example of the structure of a random access channel used in an OFDMA system;

8A and 8B show yet another example of the structure of a random access channel used in an OFDMA system;

Figure 9 shows the structure of a random access channel according to an embodiment of the present invention;

FIG. 10 shows the structure of a random access channel allocated with subframes of RACH pilots;

Fig. 11 shows the repetition structure of the preamble according to one embodiment of the present invention;

12 is a structural diagram of unit data to show one embodiment of the present invention, which transmits data by using a code sequence extended through conjugation;

13 is a flowchart illustrating a process of receiving and decoding data transmitted in a code sequence spread via conjugation, according to one embodiment of the present invention;

FIG. 14 is a structural diagram of unit data to show one embodiment of the present invention, which transmits data by using code sequences spread through packets;

15 is a flowchart illustrating a process of receiving and decoding data transmitted in code sequences spread via packets;

16 is a structural diagram of unit data to illustrate one embodiment of the present invention, which transmits data by using a code sequence extended through packetization and delay processing;

Figure 17 is a flowchart illustrating the process of receiving and decoding data transmitted in a code sequence spread via packet and delay processing;

18 is a structural diagram of unit data to show one embodiment of the present invention, which transmits data by using a code sequence spread through PPM modulation;

19 is a flowchart illustrating a process of receiving and decoding data transmitted in a code sequence spread via PPM modulation;

FIG. 20A and FIG. 20B are flowcharts of a process of performing synchronization in a random access channel according to the data transmission method of the present invention;

Figure 21 illustrates a method of transmitting data to a receiver via a signaling channel according to one embodiment of the present invention; and

Figure 22 shows an example of a receiver and transmitter for transmitting preamble and data over RACH, SCH or other channels according to one embodiment of the present invention.

Detailed ways

Hereinafter, the structure, operation and other features of the present invention can be easily understood through the preferred embodiments of the present invention, examples of which are shown in the accompanying drawings.

In a state where the UE is not uplink-synchronized with the base station, a random access channel (RACH) is used to allow the UE to access the network. Depending on the way of accessing the network, the random access mode can be divided into an initial ranging access mode and a periodic ranging access mode. According to the initial ranging access method, the user equipment obtains downlink synchronization and first accesses the base station. According to the periodic ranging access method, if necessary, the user equipment connected to the network accesses the network. The initial ranging access method is used to enable the user equipment to synchronize with the network and receive its required ID from the network while accessing the network. The periodic ranging access mode is used to start the protocol to receive data from the base station, or to start the protocol when there is a data packet to be transmitted.

In particular, the periodic ranging access scheme can be divided into two types in the 3GPP LTE (Long Term Evolution) system, namely, a synchronous access scheme and an asynchronous access scheme. When the user equipment accesses the RACH, if the uplink signal is within the synchronization limit, the synchronous access method is used. If the uplink signal is outside the synchronization limit, then the asynchronous access method is used. The asynchronous access method is used when the user first accesses the base station or does not perform synchronization update after performing synchronization. At this time, the synchronous access method is the same as the periodic ranging access method, and when the user equipment accesses the RACH for the purpose of notifying the base station of the changed state of the user equipment and requesting resource allocation, the synchronous access method is used Way.

On the other hand, the synchronous access approach alleviates the limitation of the guard time in RACH by assuming that the user equipment does not get out of uplink synchronization with the base station. For this, more time-frequency resources can be used. For example, a large number of messages (more than 24 bits) can be added to a preamble sequence for random access in synchronous access mode, so that both the preamble sequence and the message are transmitted together.

The structure of the RACH that performs the unique functions of the RACH while satisfying the aforementioned synchronous and asynchronous access schemes is now described.

FIG. 5 is a diagram showing an example of the structure of a random access channel (RACH) used in an OFDMA system. As shown in Fig. 5, note that, according to the radius of the cell, the RACH can be divided into N subframes on the time axis and M frequency bands on the frequency axis. The frequency at which the RACH is generated is determined according to QoS (Quality of Service) requirements in the Medium Access Control (MAC) layer. Generally, the RACH is generated every certain period (tens of milliseconds (ms) to hundreds of milliseconds). In this case, a frequency diversity effect and a time diversity effect are provided during generation of several RACHs while reducing collisions among user equipments accessing through the RACHs. The length of a subframe may be 0.5 milliseconds, 1 millisecond, and so on.

In the RACH structure shown in FIG. 5 , a random subframe is called a time-frequency resource (TFR) as a basic unit of data transmission. FIG. 6A is a diagram showing one type of transmitting a random access signal to a TFR in the time domain, and FIG. 6B shows one type of transmitting a RACH signal in the frequency domain.

As shown in FIG. 6A, if the random access signal is generated in the time domain, the original subframe structure is ignored, and the signal is arranged only by TFR. In contrast, as shown in FIG. 6B , in the case of the synchronous random access scheme, the subframe structure is maintained in the frequency domain, and at the same time, a random access signal to be transmitted to a subcarrier of each OFDM symbol is generated. Accordingly, orthogonality can be maintained between the respective blocks constituting the TFR, and channel estimation can be easily performed.

FIG. 7 is a diagram showing another example of the structure of the RACH used in the OFDMA system. As shown in Fig. 7, note that in the TDM/FDM scheme with RACH burst duration attached to the wideband pilot and in the TDM scheme, the preamble 'b' and the pilot 'a' partially overlap. Note also that in the TDM/FDM scheme with wideband pilot embedded and in the TDM scheme, pilot 'a' and pilot 'b' overlap preamble 'a' and preamble 'b' at the same time. In other words, the preamble and the pilot are designed to be transmitted together through the RACH so that message decoding is easily performed through channel estimation if the message is added to the RACH. Alternatively, wideband pilots are used so that channel quality information (CQI) for all RACH bands can be obtained in addition to the preamble bands of the RACH.

8A and 8B are diagrams showing another example of the structure of the RACH used in the OFDMA system.

As shown in FIG. 8A , the preamble is transmitted at a predetermined period through the frequency band, and a short block duration is provided in a certain period so that a pilot for decoding the preamble is transmitted to the corresponding short block. At this time, pilot transmission is performed through a part of the entire frequency band (transmission through 25 subcarriers of the middle band corresponding to a total of 75 subcarriers), so that the pilot can be transmitted to specific user equipment.

In addition, as shown in FIG. 8B, the message to be transmitted and the pilot used to decode the message are multiplexed and passed through some frequency bands selected from all frequency bands (for example, 25 intermediate subcarrier bands for a total of 75 subcarrier bands). carrier band) to carry on the message to be transmitted and the pilot used to decode the message. Accordingly, individual user equipments performing multiple access can be identified by allocating some frequency bands at different frequencies.

FIG. 9 is a diagram showing the structure of a RACH according to one embodiment of the present invention.

Usually, the frequency of generating RACH is determined according to the QoS requirements in the MAC layer. The RACH is generated with a variable cycle (several milliseconds to hundreds of milliseconds) according to the requirements of the cell. The RACH may be generated in the time and frequency domains as described above with reference to FIGS. 6A and 6B . In the embodiment of FIG. 9, the structure of the RACH corresponds to the case where the random access signal is generated in the frequency domain.

Referring to FIG. 9, in this embodiment, in order to overcome the defect that a longer interval is required for retrying when the user equipment fails to access the RACH, if the frequency and the amount of overhead when generating the RACH are determined, the corresponding RACH resources are distributed among in each frame of a cycle. The number of frames included in one cycle can be freely determined as necessary. At this time, it is preferable that the RACHs are separately arranged so that the RACHs are evenly assigned to each frequency band with respect to a plurality of frames constituting one cycle. However, the position of the time axis can be changed without changing the position of the frequency axis and vice versa according to the specific requirements of the cells (synchronization action or reduction of inter-cell interference) or if the system band is small. Also, the setting of any one of frequency and time may be changed to obtain the minimum interval between RACHs set in each frame.

In the embodiment of FIG. 9 , the network should notify the user equipment of the location information of the allocated RACH resources. In other words, the network can notify each user equipment of frequency information and time information occupied by RACH resources allocated to each frame included in one cycle, and each user equipment can use the location information from the network, via Random access is attempted using the allocated RACH resources. The location information of the RACH resources of each frame may be represented by subcarrier offset, subcarrier number, timing offset and symbol number. However, if the RACH information on each frame is represented by the above-mentioned four parameters, the amount of information will increase, which is not expected. Therefore, there is a need for a method of reducing the amount of information indicating the location information of the RACH allocated on each frame. The location information of the RACH may be conveyed through a broadcast channel (BCH) or other downlink control channel.

As one method, a method using a hopping pattern can be considered. The frequency hopping pattern represents a pattern composed of information indicating the frequency domain of RACH resources allocated to each frame within one cycle. In other words, in the embodiment of FIG. 9 , since the RACH resources are separately arranged so as to be evenly allocated to each frequency band with respect to a plurality of frames constituting one period, an indicator indicating that Each frame is allocated as a frequency band of the RACH resource, and the frequency band of the RACH resource allocated to each frame within one period may be notified by a pattern of an indicator indicating the corresponding frequency band.

For example, if four frames are used as one cycle in a system using a total band of 10 MHz, the position of RACH includes sub-bands (sub- band). At this time, the total band is composed of four sub-bands, in which the respective sub-bands are indicated as 1, 2, 3 and 4 in order from the high frequency band to the low frequency band by indicators indicating each sub-band. In this way, the frequency band position information of the RACH resources allocated to all frames in one period can be represented by the above-mentioned pattern constructed by the indicator, for example, 2, 3, 1, 4. The frequency hopping pattern may be configured differently or equally per frame. The time information of the RACH resources allocated to each frame within one period can generally be represented by a timing offset and the number of symbols. At this time, at least any one of the timing offset and the number of symbols may be fixed to reduce the amount of information. For example, if the timing offset and number of symbols for RACH resources pre-determined for each frame are fixed, the network only needs to transmit the frequency hopping pattern to inform the user equipment of the location information of the RACH resources of all frames within one cycle .

If each sub-band is narrow or considering the influence of interference between user equipments, frequency hopping patterns for all frames may be equally set. In this case, the network only needs to report the frame period to the user equipment.

Hereinafter, a process of transmitting uplink data from a user equipment to a base station by using the RACH structure of the embodiment as shown in FIG. 9 will be described. In this case, data transmission is performed through RACH in a reverse common channel consisting of a plurality of frames.

First, the user equipment tries to access the dispersed RACH included in the current frame to transmit its information to the base station. If the user equipment successfully accesses the RACH, the user equipment transmits preamble data via the corresponding RACH. However, if the user equipment fails to access the RACH, the user equipment tries to access the RACH separately arranged in the next sequential frame. At this time, if the frequency band is not wide enough or there is no specific requirement (inter-cell interference or limitation of the activity range of the user equipment), it is preferable to arrange the RACH included in the frame of the next order in a frequency band different from that of the RACH of the previous frame . Moreover, the above access process is continued in the next sequence of frames until the user equipment successfully accesses the RACH.

Meanwhile, in the case of synchronous RACH, subframes of each frame preferably include short blocks to which pilots for user equipments that have accessed the corresponding RACH are allocated. At least one RACH pilot and access pilot may be assigned to the short block in a predetermined pattern. In other words, the user equipment that has accessed the RACH should know the channel information to receive the channel from the base station. Channel information can be set in the RACH pilot within the uplink short block. The base station allocates an appropriate channel to the user equipment through the corresponding RACH pilot. Meanwhile, if a user equipment having access to RACH notifies the base station of channel quality information on whether the user equipment is preferably allocated a channel through the RACH pilot, an appropriate channel can be allocated to the user equipment during scheduling, thereby maintaining high-quality communication.

Accordingly, a RACH pilot for a user equipment having accessed the RACH may be individually allocated to a subframe including the RACH. Therefore, the user equipment accessing the RACH sends the preamble to the base station through the corresponding RACH and sends the pilot used to transmit the channel quality information to the designated RACH pilot. The RACH pilot is a sequence specified according to the preamble, and preferably, if possible, user equipments using different preamble sequences use different RACH pilot sequences or select RACH pilots of different subcarriers or partially overlap subcarriers.

FIG. 10 is a diagram showing a structure of a random access channel of a subframe to which RACH pilots are allocated. Note that each subframe includes at least one short block to which at least one RACH pilot and access pilot are allocated in a predetermined pattern. In this case, RACH pilots exist in the frequency band to which RACH is allocated and other system bands. In this embodiment, it has been described that there are two short blocks in each frame, and RACH pilots are transmitted to the short blocks. However, the present invention is not limited to such embodiments, and various modifications can be made within the scope apparent to those skilled in the art.

As described above, it has been described that a preamble, synchronization timing information including pilot information, uplink resource allocation information, and messages (eg, uplink data) can be transmitted through the RACH of various structures. Obviously, the data transmission method according to the embodiment of the present invention can be used for RACH and other channels.

At the same time, preamble and message can be transmitted separately through RACH. Alternatively, the message can be transmitted by implicitly enclosing it in a preamble. One embodiment of the present invention relates to a method of transmitting a preamble through the latter transmission mode. In one embodiment of the present invention, a more extended code sequence than that of the related art can be used for efficient transmission of the preamble. Hereinafter, a method for improving a CAZAC sequence for efficient transmission of a preamble according to an embodiment of the present invention will be described.

Since the receiver should search for the starting position of the transmission signal in the random access channel, the transmission signal is usually designed to have a specific pattern in the time domain. For this, a preamble is repeatedly transmitted in the frequency domain or a certain interval is maintained between subcarriers to obtain a repetition characteristic in the time domain, thereby identifying timing synchronization.

In the former case, the preamble represents a reference signal for initial synchronization setup, cell detection, frequency offset and channel estimation. In cellular mobile communication systems, sequences with excellent cross-correlation properties are preferably used for repeated transmission of preambles. For this, binary Hardamard codes or polyphase CAZAC sequences can be used. Specifically, since a CAZAC sequence is represented by a Dirac-Delta function in the case of autocorrelation and has a constant value in the case of cross-correlation, it is estimated that the CAZAC sequence has excellent transmission characteristics.

CAZAC sequences can be classified into the following GCL sequences (Equation 1) and Zadoff-Chu sequences (Equation 2).

【Formula 1】

$c(k;N,m)=\exp (-\frac{\mathrm{j\πMk}(k+1)}{N})$ N is an odd number

$c(k;N,m)=\exp (-\frac{\mathrm{j\π}{\mathrm{Mk}}^2}{N})$ N is an even number

【Formula 2】

$c(k;N,m)=\exp \left(\frac{\mathrm{j\πMk}(k+1)}{N}\right)$ N is an odd number

$c(k;N,m)=\exp \left(\frac{\mathrm{j\π}{\mathrm{Mk}}^2}{N}\right)$ N is an even number

In the above formula, note that if the CAZAC sequence has length N, the actually available sequences are limited to N-1 sequences. Therefore, the number of CAZAC sequences must be increased to efficiently use them in practical systems.

For example, a method is proposed to provide an improved CAZAC sequence p(k) by multiplying the CAZAC sequence c(k) with a predetermined modulation sequence m(k), thereby increasing the number of available sequences by one. In other words, assuming that a Zadoff-Chu sequence is used as the CAZAC sequence, the CAZAC sequence c(k), modulation sequence m(k), and improved CAZAC sequence p(k) can be defined by the following formulas 3, 4, and 5, respectively.

【Formula 3】

CAZAC sequence:

$\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ;</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; j\&pi;Mk</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; )</span>$

【Formula 4】

modulation sequence

$\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;\&sigma;</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>$

【Formula 5】

Improved CAZAC sequence (or improved preamble):

$\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; j\&pi;M</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;\&delta;</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>$

The improved CAZAC sequence p(k) maintains the autocorrelation and cross-correlation properties of CAZAC sequences. Equation 6 below shows the autocorrelation characteristic of p(k), and it can be known from Equation 6 that the final result is a Dirac-delta function. Specifically, if the modulation sequence m(k) is a sequence with a certain phase, it is characterized in that the modulation sequence m(k) always maintains the autocorrelation property.

【Formula 6】

$\mathrm{<span\; class="notranslate">\; ad</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; j\&pi;M</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;\&delta;</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>$

$\exp (-\frac{\mathrm{j\&pi;M}}{N}k(k+1)-\frac{j2\mathrm{\&pi;\&delta;}}{N}k)$

$=\underset{k}{\mathrm{\&Sigma;}}\exp (\frac{j2\mathrm{\&pi;M}}{N}(2\mathrm{dk}+d(d+1))+\frac{j2\mathrm{\&pi;\&delta;}}{N}d)$

$=\exp \left(\frac{j2\mathrm{\&pi;\&delta;}}{N}d\right)\underset{k}{\mathrm{\&Sigma;}}\exp (\left(\frac{\mathrm{j\&pi;M}}{N}(2\mathrm{dk}+d(d+1))\right)=\left\{\begin{array}{cc}1& d=0\\ 0& d\&NotEqual;0\end{array}\right.$

Furthermore, Equation 7 below shows the cross-correlation characteristic of p(k).

【Formula 7】

$\mathrm{<span\; class="notranslate">\; cc</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; j\&pi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;\&delta;</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>$

$\exp (-\frac{\mathrm{j\&pi;M}}{N}k(k+1)-\frac{j2\mathrm{\&pi;\&delta;}}{N}k)$

$=\underset{k}{\mathrm{\&Sigma;}}\exp \left(\frac{\mathrm{j\&pi;x}}{N}(k+d)(k+d+1)\right)$

$\exp (\frac{\mathrm{j\&pi;M}}{N}(k+d)(k+d+1)+\frac{j2\mathrm{\&pi;\&delta;}}{N}(k+d))$

$\exp (-\frac{\mathrm{j\&pi;M}}{N}k(k+1)-\frac{j2\mathrm{\&pi;\&delta;}}{N}k)$

$=\exp \left(\frac{\mathrm{j\&pi;x}}{N}(k+d)(k+d+1)\right)$

$\exp (\frac{j\mathrm{\&pi;M}}{N}(2\mathrm{dk}+d(d+1))+\frac{j2\mathrm{\&pi;\&delta;}}{N}d)$

$=\exp \left(\frac{\mathrm{j\&pi;M}}{N}d(d+1)\right)\underset{k}{\mathrm{\&Sigma;}}\exp \left(\frac{\mathrm{j\&pi;x}}{N}(k+d)(k+d+1)\right)$

$\exp \left(\frac{j2\mathrm{\&pi;dM}}{N}k\right)$

In this case, although Equation 7 appears to be similar to Equation 6, note that, in terms of the summation term, the autocorrelation is represented by the sum of the exponents, while the cross-correlation is represented by the product of the two series. The first term is another CAZAC sequence with a seed value of x, and the second term is a simple exponential function. The sum of the products of two sequences is equivalent to obtaining the coefficient of the exponential function, and its value is equivalent to the value obtained by converting the CAZAC sequence whose seed value is x into the frequency domain and taking the value from the frequency position of the index.

Since the CAZAC sequence has the autocorrelation of Dirac-delta characteristics, if it is Fourier transformed, it will maintain the autocorrelation characteristics of equal amplitude Dirac-delta even in the transformed area. For this, if you take the values at specific positions from the frequency domain, they have magnitude 1 and are equal to each other, but their phases are different from each other. Therefore, if this result is added to Equation 7 to obtain cross-correlation, the obtained cross-correlation can be briefly expressed by Equation 8 below.

[Formula 8]

$\mathrm{<span\; class="notranslate">\; cc</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; j\&pi;M</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;\&delta;</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; )</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; j\&pi;x</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>$

$\exp \left(\frac{j2\mathrm{\&pi;dM}}{N}k\right)$

$=\exp (\frac{\mathrm{j\&pi;M}}{N}d(d+1)+\frac{j2\mathrm{\&pi;\&delta;}}{N}d)C(D/N;x)$

It can be known from formula 8 that since the size of C(dM/N; x) is always 1, and the size of the exponential term is also 1, the cross-correlation is always fixed at 1.

Finally, through Equation 5, the characteristics of the related art CAZAC sequence can be maintained, and the number of codes can be increased at the same time. This means that the result in the region where the exponential term is multiplied is equivalent to applying a cyclic shift to the Fourier transform region, and multiplying an exponential sequence in the time domain is equivalent to performing a cyclic shift in the frequency domain.

In other words, note that if one obtains the correlation between two sequences p(k; M, N, d1) and p(k; M, N, d2) whose seed values are equal to each other, the delay in the cross-correlation A pulse occurs at the point at which the value d reaches d1-d2. Although the improved sequence design described above has the same result as the cyclic shift of the CAZAC sequence, embodiments of the present invention are also advantageous because the result can be obtained by a simple procedure such as Fourier transform and After the cyclic shift, the two exponential sequences are multiplied without inverse Fourier transform.

Hereinafter, a method of improving data transmission reliability of a preamble by performing predetermined data processing of a related art code sequence and a method of extending the length of a code sequence when simultaneously transmitting data will be described. If a CAZAC sequence is used as a code sequence, the CAZAC sequence extended by the above method is preferably used. However, the CAZAC sequence is not necessarily limited to the CAZAC sequence extended by the above method, and a related art CAZAC sequence may also be used.

First, what will be described is the structure of transmission data (ie, preamble) generally applied to the embodiments of the present invention.

In the 3GPP LTE (Long Term Evolution) system, the transmitter can repeat the transmission of the same sequence two or more times in order to allow the receiver to easily detect the transmitted data or to improve additional detection performance (ie, increase the spreading gain). Therefore, regardless of the type of the received sequence, the receiver only needs to detect the repetitive pattern, so the time position of the user equipment accessing the RACH can be easily identified and the detection performance can be improved.

FIG. 11 is a diagram showing the structure of a preamble according to one embodiment of the present invention. In OFDM transmission systems, a cyclic prefix (CP) is used, in which the last part of the OFDM symbol is copied and then prepended to the OFDM symbol to compensate for multipath loss in signal transmission. Therefore, if an OFDM symbol consists of two repeated preambles, a part of the latter order preamble is copied to the first part by the CP to compensate for the multipath loss of the corresponding preamble. Also, CP is advantageous because it easily identifies user equipments accessing different RACHs in case CAZAC has good cycle correlation.

Since inter-symbol interference does not occur even if a single sequence is transmitted into it by a preamble CP instead of repeated transmission of the sequence, a predetermined reception algorithm can be realized without hindrance in the frequency domain. However, if the receiver implements the receiving algorithm in the time domain using neither repeated transmission nor CP, the receiver should detect various code sequences to identify user equipments accessing the RACH. In view of this, the preamble is preferably realized by the structure of a repeating pattern. At this time, whether to implement the repeating pattern may be determined according to the data rate supported by the system, or, if the repeating pattern is implemented, the number of repetitions may be determined. For example, in order to support the minimum data rate supported by the system, the RACH preamble may be transmitted repeatedly one or more times according to the length of the sequence.

First, first to fourth embodiments related to a data processing method of a sequence constituting a preamble structure will be described below. In these embodiments, the data transmitted to the receiver may be the preamble structure of Figure 11, or a partially omitted structure (neither repeated transmission nor CP). Although it is assumed that CAZAC sequences are used as code sequences for data transmission, the code sequences are not necessarily limited to CAZAC sequences. Various sequences having excellent transmission characteristics, such as Hadarmad codes and gold codes, can be used as code sequences.

<First embodiment>

In order to transmit data, the transmission signals making up the data usually require identifiable landmarks. In this example, conjugates are used as landmarks. Since the phase variation width between the conjugate transmission signal and other transmission signals is large, the interference between transmission signals is reduced, whereby the reliability of data transmission can still be improved regardless of channel influence.

FIG. 12 illustrates a method of transmitting data through conjugation according to one embodiment of the present invention. In the embodiment of FIG. 12, one CAZAC sequence is divided into four blocks, and "0" or "1" indicates whether to perform conjugation for each block. For example, it can be set that an unconjugated block is represented by "0", and a conjugated block is represented by "1". In this way, a CAZAC sequence can represent 4-bit information. In other words, if a CAZAC sequence is divided into N blocks, it can represent N bits of information.

At this time, in a single CAZAC sequence having a longer length corresponding to the transmission data length, a part of a single CAZAC sequence corresponding to a specific block having a value of 1 may be conjugated. Also, among a plurality of CAZAC sequences having a shorter length corresponding to the length of each block of transmission data, a CAZAC sequence corresponding to a specific block having a value of 1 may be conjugated.

FIG. 13 is an example showing a method of receiving and decoding a sequence transmitted from a transmitter through conjugation according to one embodiment of the present invention.

Preferably, the transmitter always assigns the value 0 to the first block of transmitted data, so that this first block is subsequently used as a reference. Accordingly, the receiver identifies the sequence ID of the received first block (S1101), and then measures a peak value by using only the corresponding block (S1102). Next, the receiver identifies the serial IDs of the first block and the second block (S1103), and then measures the peak value by using the first block and the second block together. At this time, since it is not clear whether the sequence of the second block is in a conjugated state, the receiver respectively measures the peak value corresponding to the case where the corresponding block is conjugated (S1104) and measures the peak value corresponding to the case where the corresponding block is not conjugated. The peak of the situation (S1105), and then select the larger one of the two peaks (S1106). Subsequently, the receiver identifies the sequence IDs of the first to third blocks (S1107), and then uses the first to third blocks together to measure peak values. In this case, since it is not clear whether the sequence of the third block is in a conjugated state, the receiver respectively measures the peak corresponding to the case where the corresponding block is conjugated (S1108) and measures the peak value corresponding to the case where the corresponding block is not conjugated. The peak of the situation of the yoke (S1109), and then select the larger one of the two peaks (S1110). In this way, decoding is performed on the first tile to the last tile, thereby finally decoding the original data.

<Second Embodiment>

FIG. 14 is a diagram illustrating a method of transmitting data using a sequence according to another preferred embodiment of the present invention. Although data transfer is performed by changing the sequence in the first embodiment, in this embodiment, the sequence type used to represent one block is divided into a sequence (first sequence) with a block value of "0" and a block A sequence with a value of "1" (second sequence), and the first sequence and the second sequence are grouped. In this case, since the receiver only detects the sequence ID (first sequence ID or second sequence ID) of each block, the receiver is less affected by noise or channel.

All sequences consist of a group obtained by grouping two subsequences (first sequence and second sequence) (i and j are integers different from each other) "{ c0(k; M _i ), c1(k; M _j )}" to represent. In this case, c ₀ (k; M _i ) is the first sequence with a block value (or bit value) of 0, and c ₁ (k; M _j ) is the second sequence with a block value of 1. At this time, a CAZAC sequence having a longer length corresponding to the transmission data length can be used as each subsequence constituting each group. Alternatively, a CAZAC sequence having a shorter length corresponding to the length of each block of transmission data may be used as each subsequence constituting each group.

At the same time, the receiver recognizes the sequence ID of each block, and recognizes the sequence type (first sequence or second sequence) of each block from the sequence ID set consisting of the recognized sequence IDs. At this time, the sequence type of each block can be represented by a group ID. In other words, in this embodiment, since it is assumed that the code value of each block can be represented by 0 and 1, two sequence types or two types of group IDs for each block are obtained. The code value of each block can be retrieved through the group ID. This decoding process will be described in detail below with reference to FIG. 15 .

If a sequence is received, the receiver identifies a sequence ID of each block constituting the corresponding sequence (S1501), and measures a peak value of a sequence ID set composed of the identified sequence IDs (S1502). In this case, two peaks having higher frequencies when generated are selected (S1503) in order to identify the sequence generating the corresponding peaks as the first sequence and the second sequence constituting the group. At this time, if the first sequence and the second sequence are respectively represented by predetermined group IDs, the first group ID representing a code value of 0 and the second group ID representing a code value of 1 may be respectively identified. Finally, the group ID of each block can be identified through step S1503 (S1504), and thus the code value of each block can be identified (S1508).

If there is a sequence ID for which the group ID cannot be identified due to an error occurring during the decoding process, a peak is searched in the set of corresponding sequence IDs (S1505), and, among these peaks, two strong peaks are detected (S1506), thereby The group ID is again identified from the detected strong peaks (S1507). Subsequently, the code value of the corresponding block can be identified from the identified group ID (S1508).

<Third embodiment>

FIG. 16 is a diagram illustrating a method of transmitting data using a sequence according to another preferred embodiment of the present invention.

If the second embodiment is further extended, the total number of data bits that can be transmitted by one group can be increased. For example, if two sequences are limited to one group as in the second embodiment, data of 1 bit per block can be transmitted. If four sequences are defined as one group, data of 2 bits per block can be transmitted. If eight sequences are defined as one group, data of 3 bits per block can be transmitted. However, since multiple sequences are grouped and limited to a set, there is a problem that if the length of each sequence is short, the number of selectable groups decreases in proportion to the short length of each sequence .

Therefore, the length of the sequence must be extended to increase the number of groups that can be selected. For this reason, in this embodiment, the sequence length of each block is extended, and the sequences are overlapped multiple times as shown in FIG. 16B , and the independence is maintained due to the transmission delay between overlapping sequences.

Referring to Fig. 16(a), a data value of 2 bits is assigned to each block. Therefore, the sequence group of each block consists of four different CAZAC sequences. Since each CAZAC sequence forming a sequence group should recognize four values, the group size should be increased accordingly. In this case, however, there is a problem that the number of groups usable by each base station is reduced. Correspondingly, as shown in FIG. 16, the length of each CAZAC sequence is extended as much as necessary, and a predetermined delay is given to each CAZAC sequence during data transmission, whereby the independence between the respective CAZAC sequences is maintained .

Meanwhile, the receiver recognizes the ID of the corresponding block based on the order of each CAZAC sequence represented in the time/frequency domain, and the method of decoding the code value from the corresponding block ID is almost the same as that of the second embodiment. Hereinafter, a data decoding process of a receiver will be described in detail with reference to FIG. 17 .

If a sequence is received, the receiver identifies a sequence ID of each block constituting the corresponding sequence (S1701), and measures a peak value of a sequence ID set composed of the identified sequence IDs (S1702). In this embodiment, since one block represents 2 bits, the first, second, third and fourth sequences representing 00, 01, 10, 11 form a group. Therefore, as a measurement result, the receiver should select 4 peaks having higher frequencies when generated (S1703). In this case, the selected peaks are mapped to the first, second, third and fourth sequences respectively according to the order expressed in the time/frequency domain. Also, if the first sequence to the fourth sequence are respectively represented by predetermined group IDs, the first group ID representing the code value 00, the second group ID representing the code value 01, the third group ID representing the code value 10, and Indicates the fourth group ID with code value 11. Finally, the group ID of each block can be identified through step S1703 (S1704), so the code value of each block can be identified (S1708).

If there is a sequence ID that cannot recognize the group ID due to an error in the decoding process, the peaks are searched again in the set of corresponding sequence IDs (S1705), and among these peaks, four strong peaks are detected (S1706), thereby again The group ID is identified from the detected strong peaks (S1707). Then, the code value of the corresponding block can be identified from the identified group ID (S1708).

<Fourth Embodiment>

FIG. 18 is a diagram illustrating a method of transmitting data using a sequence according to another preferred embodiment of the present invention.

In the case of further extending the second and third embodiments, the signal position is changed by pulse position modulation (PPM) so that the sequence length can be logically extended. PPM initially transmits data with a relative pulse delay, but in this embodiment a PPM based on the start of the sequence is used.

If the data bits to be transmitted are determined, the base station selects a sequence for the corresponding data transmission and determines the block length to apply the PPM to the corresponding sequence and the length of the duration constituting each block. When generating a preamble, a sequence corresponding to each block is individually required. However, in this embodiment, since a cyclic shift equivalent to a particular duration in a particular block constituting the corresponding sequence is applied to the same sequence, the respective sequences are initially identical to each other but are identified from each other by the cyclic shift .

For example, suppose a sequence length is divided into four blocks (block 1 to block 4) and each block is represented by 2 bits, and each block is divided into four durations (from duration 1 to duration Time 4) to represent the value "00, 01, 10, 11". At this time, four durations included in one block are used as start identification positions to cyclically shift the sequence corresponding to the corresponding block. If the preamble to be transmitted has a total length of 256, block 1 has a cyclic shift value of 0-63, block 2 has a cyclic shift value of 64-127, block 3 has a cyclic shift value of 128-195, and Block 4 has a cyclic shift value of 196-255. If a specific sequence for the transmission of the preamble is determined, "00" is transmitted through block 1, which is subjected to a cyclic shift, thereby setting the start position in duration 1 (0-15) of block 1 . If "10" is transferred to block 2, sequence 2 undergoes a cyclic shift, setting the start position in duration 3 of block 2 (96-111). In this way, the cyclic shift is applied to other blocks, and then the respective sequences (from sequence 1 to sequence 4) are combined into one group to generate a preamble. In this case, the number of blocks can be generated from 1 to any random number. Also, the minimum unit of cyclic shift can be limited to exceed a certain value in consideration of channel or timing errors.

Meanwhile, the receiver identifies the respective subsequences (from Sequence 1 to Sequence 4) constituting the corresponding sequence by performing data processing on the transmitted sequence, and searches the start position of each identified sequence to perform data decoding. This process will be described in detail with reference to FIG. 19 .

If a sequence is received in the receiver (S1901), the receiver detects the ID of the corresponding sequence (S1903), and performs full correlation by performing predetermined data processing on all received signals (received sequences) by using the detection result (S1905). At this time, a complete search algorithm or a differential search algorithm can be used to detect the sequence ID.

Since signals are transmitted and received from a transmitter by combining multiple sequences, the signal that has been subjected to correlation includes multiple peaks. In this embodiment, four peaks are detected, and the receiver determines which one of block 1 to block 4 each detected peak corresponds to and which duration of the corresponding block (S1909) to decode Bit order and bit value of raw data (S1911).

Methods of efficiently transmitting preamble sequences and messages over the RACH have been described above. Finally, the process of transmitting a preamble from a user equipment (UE) to a base station (Node B) and performing synchronization between both the user equipment and the base station will be described according to two embodiments. Figures 20A and 20B illustrate these two embodiments.

In the embodiment of Fig. 20A, synchronization is performed in such a way that the user equipment only visits the base station once. In other words, if the user equipment transmits the preamble and messing including the information required for synchronization to the base station (S2001), the base station transmits the timing information to the user equipment (S2003) and at the same time allocates the timing information for the uplink resources for data transmission (S2005). The user equipment transmits uplink data to the base station through the allocated resources (S2007).

In the embodiment of Fig. 20B, for synchronization, the user equipment visits the base station twice. In other words, if the user equipment transmits the preamble to the base station (S2011), the base station transmits timing information to the user equipment (S2013) and at the same time allocates resources for requesting scheduling (S2013). The user equipment transmits a message for requesting scheduling to the base station through the allocated resources (S2015). Then, the base station allocates resources for transmission of uplink data to the user equipment (S2017). Through this method, the user equipment transmits uplink data to the base station through the secondary allocated resources (S2019).

FIG. 21 is a diagram illustrating a method of transmitting data to a receiver through a signaling channel according to one embodiment of the present invention.

Since the receiver should search for the start position of the transmitted signal during the actual implementation of the random access channel, its common design is to make the random access channel have a specific pattern in the time domain. For this, a preamble sequence can be used so that the random access signal initially has a repeating pattern. Alternatively, a certain spacing can be maintained between subcarriers in the frequency domain to obtain a repetitive signature in the time domain. Therefore, the access method of FIG. 6A and FIG. 6B is characterized in that the start position of the transmission signal should be easily searched in the time domain. For this, CAZAC sequences are used. CAZAC sequences can be classified into GCL sequences (Equation 1) and Zadoff-chu sequences (Equation 2).

Meanwhile, a specific sequence of longer length is preferably used to transmit unique information of a user equipment or a base station through RACH (Random Access Channel) or SCH (Synchronization Channel). This is because the receiver can easily detect the corresponding ID, and more different kinds of sequences can be used to facilitate system design.

However, if the message is transmitted using the corresponding ID of a longer-length sequence, since the amount of information increases with a log ₂ function, there is a limit to using ID for message transmission only when the sequence exceeds a certain length. Therefore, in this embodiment, where the sequence is separated by blocks, a sequence of short signatures corresponding to the data to be transferred to each block of the sequence is used, rather than specific operations such as conjugation or negation.

Referring to FIG. 21 , the sequence is divided into a predetermined number of blocks, and a short signature sequence corresponding to the data to be transmitted is applied to each divided block. The long CAZAC sequence is multiplied with the combination of blocks to which the short signature sequence is applied, thereby completing the final data sequence to be transmitted to the receiver.

In this case, assuming the short signature sequence consists of four signatures, the following set of signatures can be used. Also, if there is a difference between the individual data constituting the signature set, any other signature set may be used without specific limitations.

1) Modulation value: {1+j, 1-j, -1-j, -1+j}

2) Index sequence: {[exp(jw ₀ n)], [exp(jw ₁ n)], [exp(jw ₂ n)], [exp(jw ₃ n)]}, where n=0... Ns, and Ns is the length of each block

3) Walsh Hadamard sequence: {[1111], [1-11-1], [11-1-1], [1-1-11]}, where, if the length Ns of each block is longer than 4, then Repeat each sequence to adjust length.

Examples of long CAZAC sequences that can be used in the embodiment of FIG. 21 include, but are not limited to: a GCL CAZAC series, Zadoff-Chu sequences, and combinations of two or more short GCLs of the same length or different lengths or Sequence generated by Zadoff-ChuCAZAC sequence.

The above-described method of applying the short signature sequence used for data transmission and reception to the long CAZAC sequence is advantageous in that the modulation method of the transmitted data is less affected by the channel than the related art, and that although the bits constituting one signature Its performance hardly diminishes as its numbers increase.

Figure 22 shows an example of a receiver and transmitter for transmitting preambles and data via RACH, SCH or other channels in the aforementioned manner.

Since the number of bits can be increased according to the signature, channel coding can be applied to the transmitter. If channel coding is performed, time diversity/frequency diversity can be obtained by an interleaver. Also, bit-to-signature mapping can be performed to minimize the bit error rate. In this case gray mapping can be used. Mix the sequence that has gone through this procedure with CAZAC and send it.

The receiver detects the CAZAC ID and calculates the log-likelihood ratio (LLR) for each bit. The receiver then decodes the transmitted data through a channel decoder. Considering the complexity of the sequence search according to the receiver as configured in FIG. 22 , the transmitter preferably uses the index sequence as the signature sequence. In this case, the receiver can easily search for CAZAC ID by phase-difference Fourier transform. The receiver can then easily compute the LLRs from the signature again by Fourier transform.

According to the present invention, the structure on the frequency axis/time axis of the RACH can be more clearly recognized. Also, since RACH resources are allocated separately to each frame, even if the user equipment fails to access a specific RACH, the user equipment can directly access the RACH of the next frame, whereby access to the base station is improved. In addition, user equipment can easily access RACH even if the service area of QoS conditions is very limited.

In addition, according to the present invention, since information is transmitted and received between the user equipment and the base station by using coded sequences, time diversity/frequency diversity can be maximized, and performance due to channel influence can be weakened by signature attenuation.

According to the present invention, since the total length of the corresponding sequence can be used while maintaining the advantages of the coding sequence according to the related art, data transmission can be performed more efficiently. Also, since the coded sequence is subjected to predetermined data processing, the amount of information to be transmitted can be increased, and the transmitted data becomes more robust against noise or a channel.

It will be apparent to those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit and essential characteristics of the present invention. Accordingly, the above-described embodiments are to be considered in every respect as illustrative and not restrictive. The scope of the present invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the present invention are included in the scope of the present invention.

Industrial Applicability

The present invention is applicable to wireless communication systems such as mobile communication systems or wireless Internet systems.

Claims (30)

1. A method for transmitting data on a random access channel in a mobile communication system, the method comprising: generate new codes by multiplying the sequence of codes with the sequence of indices; and Transmit the new code sequence to the recipient. 2. The method according to claim 1, wherein the code sequence is a CAZAC (Constant Amplitude Zero Autocorrelation) sequence. 3. The method according to claim 1 or 2, wherein the code sequence is transmitted as a preamble. 4. A method of transmitting data by using a code sequence in a mobile communication system, the method comprising: conjugating at least one element included in at least one block in the code sequence divided into at least two blocks to indicate predetermined information; and The code sequence in which the at least one block is conjugated is transmitted to a recipient. 5. The method of claim 4, wherein the code sequence is a CAZAC sequence. 6. A method of transmitting data by using code sequences in a mobile communication system, the method comprising: generating a second code sequence indicating predetermined information by combining at least two first code sequences mapped with at least one information bit, respectively; and The second code sequence is transmitted to a recipient. 7. The method of claim 6, wherein the first code sequence is a CAZAC sequence. 8. The method according to claim 6, wherein if each of said first code sequences is mapped with 'n' information bits, then selecting all of them from the sequence group consisting of 2 ⁿ first code sequences said at least two first code sequences. 9. The method of claim 6, wherein said at least two first code sequences are summed after a predetermined delay is given to each of said at least two first code sequences, thereby performing said Said combination of at least two first code sequences. 10. A method of transmitting a code sequence in a mobile communication system, the method comprising: generating a combined code sequence by combining a base code sequence to at least one code sequence obtained via a cyclic shift of said base code sequence; and The combined code sequence is transmitted to a recipient. 11. The method of claim 10, wherein each of the base code sequence and the at least one code sequence identifies one or more information bits. 12. The method of claim 10, wherein the step of generating the combined code sequence is performed in the frequency domain. 13. The method of claim 10, wherein the step of generating the combined code sequence is performed in the time domain. 14. The method of claim 10, wherein the combined code sequence is transmitted over a random access channel (RACH). 15. The method of claim 10, wherein the at least one code sequence is obtained by cyclic shifting of the base code sequence as many as integer multiples of cyclic shift units. 16. A method of transmitting a code sequence in a mobile communication system, the method comprising: generating a repeating code sequence by repeating the concatenated first code sequence at least one or more times; generating a cyclic prefix (CP) by duplicating a portion of the back end of the repeated code sequence and concatenating the copied portion to the front end of the repeated code sequence; and The repeating code sequence is transmitted to the receiver, and the CP is generated in the repeating code sequence. 17. The method of claim 16, wherein the repeating code sequence is transmitted as a preamble on a random access channel. 18. A method of allocating random access channels in a multi-carrier system, the method comprising: assigning a random access channel to each of at least two adjacent frames such that frequency bands of the random access channels assigned to the at least two adjacent frames do not overlap each other; and The allocation information of the random access channels allocated to the at least two adjacent frames is transmitted to at least one user equipment. 19. The method of claim 18, wherein the frequency bands allocated to the random access channels of the at least two adjacent frames have a periodically repeating pattern. 20. The method of claim 18, wherein the allocation information includes a frequency hopping pattern of frequency bands of the random access channel allocated to the at least two adjacent frames. 21. The method of claim 18, wherein the random access channel is evenly allocated to the at least two adjacent frames. 22. The method according to claim 18, further comprising allocating a channel region for pilot signal transmission at the user equipment to at least one subframe to which the random access into the channel. 23. The method of claim 22, wherein the user equipment attempting random access through the random access channel transmits a pilot signal through the channel region. 24. A method of transmitting data using code sequences in a mobile communication system, the method comprising: respectively mapping each of the plurality of blocks having at least one bit of the input data stream to a corresponding signature sequence; multiplying a stream of signature sequences to which the plurality of blocks are mapped by a specific code sequence; and Transmitting said signature sequence stream multiplied by said specific code sequence to a recipient. 25. The method of claim 24, wherein the particular code sequence is a single CAZAC sequence. 26. The method of claim 24, wherein the specific code sequence is a sequence obtained by concatenating at least two different CAZAC sequences. 27. The method of claim 24, wherein the signature sequence is a sequence of indices. 28. The method of claim 24, wherein the signature sequence is a Hadamard sequence. 29. The method of claim 24, further comprising repeating each signature sequence such that the length of the signature sequence stream matches the length of the particular code sequence, wherein the plurality of blocks map to the signature sequence sequence flow. 30. The method of claim 24, wherein the signature sequence map is a Gray map.

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