CN101636937A - Method of generating random access preambles in wireless communication system - Google Patents

Abstract

A method of generating random access preambles includes receiving information on a source logical index and generating random access preambles in the order of increasing cyclic shift from root ZC sequences with the consecutive logical indexes from the beginning of the source logical index until a predetermined number of the random access preambles are found, wherein the consecutive logical indexes are mapped to root indexes of the root ZC sequences.

Description

Method for generating random access preamble in wireless communication system

technical field

The present invention relates to wireless communication, in particular to a method for generating a random access preamble in a wireless communication system.

Background technique

3GPP (3rd Generation Partnership Project: Third Generation Partnership Project) mobile communication systems based on WCDMA (Wideband Code Division Multiple Access) wireless access technology are widely deployed around the world. HSDPA (High Speed Downlink Packet Access: High Speed Downlink Packet Access) can be defined as the first evaluation stage of WCDMA, which provides a highly competitive wireless access technology in the medium and long term. However, since radio access technologies are being steadily developed to meet increasing needs and expectations of users and providers, new technological evolution is required in 3GPP to secure future competitiveness.

One system considered to be compatible with the third-generation system is an OFDM (Orthogonal Frequency Division Multiplexing) system that reduces inter-symbol interference (ISI) with low complexity. In OFDM, serially input data symbols are converted into N parallel data symbols and transmitted on N orthogonal subcarriers. These subcarriers remain orthogonal in the frequency domain. Each orthogonal channel experiences frequency-selective fading independently of each other, and when the interval between symbols is long enough, ISI can be eliminated. OFDMA (Orthogonal Frequency Division Multiple Access: Orthogonal Frequency Division Multiple Access) refers to a multiple access method that uses OFDM as a modulation scheme. In OFDMA, frequency resources (ie, subcarriers) are provided to individual users. In this case, since respective frequency resources are independently provided to a plurality of users, these frequency resources do not overlap with each other. That is, these frequency resources are allocated exclusively to user(s).

In order to send or receive data packets, control information needs to be sent. For example, the uplink control information includes an ACK (Acknowledgment: acknowledgment)/NACK (Negative-Acknowledgment negative acknowledgment) signal indicating the successful transmission of downlink data, and a CQI (Channel Quality Indicator: channel quality indication) indicating the quality of the downlink channel. symbol), PMI (Precoding Matrix Index: precoding matrix index), RI (Rank Indicator: rank indicator), etc. Also, a random access preamble needs to be transmitted to perform a random access procedure.

Sequences are typically used to send uplink control information or random access preambles. Sequences are transmitted via a control channel or a random access channel as spreading codes, user equipment identifiers or signatures.

FIG. 1 is an exemplary diagram illustrating a method of performing a random access procedure in a WCDMA system. A random access procedure is performed to allow the user equipment to acquire uplink synchronization with the network or to acquire uplink radio resources for transmitting uplink data.

Referring to FIG. 1 , a user equipment transmits a preamble via a PRACH (Physical Random Access Channel: Physical Random Access Channel), which is an uplink physical channel. The preamble is sent during the access slot of 1.33ms. The preamble is randomly selected from 16 preambles.

Once the base station receives the preamble from the user equipment, the substrate transmits a response via AICH (Acquisition Indicator Channel: Acquisition Indicator Channel) which is a downlink physical channel. The base station sends an acknowledgment (ACK) or negative acknowledgment (NACK) to the user equipment via the AICH. If the user equipment receives the ACK, the user equipment uses the OVSF (Orthogonal Variable Spreading Factor: Orthogonal Variable Spreading Factor) code corresponding to the preamble to send a message with a length of 10ms or 20ms. If the user equipment receives NACK, the user equipment retransmits the preamble in an appropriate time. If the user equipment does not receive a response corresponding to the previously transmitted preamble, the user equipment transmits a new preamble at a power level higher than that of the previous preamble after elapse of a predetermined access slot code.

The user equipment acquires information on 16 preambles (ie, sequences) and uses one selected from the 16 preambles as a preamble in a random access procedure. If the base station informs the user equipment of information about each available sequence, signaling overhead will increase. Therefore, usually the base station pre-specifies a sequence set and transmits the index of the sequence set to the 16 preambles. To this end, the user equipment and the base station should respectively store the sequence set according to the index in their buffers. This can be troublesome if the number of sequences belonging to that sequence set increases or if the number of sequence sets increases.

In order to enhance the data detection performance of the receiver and improve the capability, the correlation or CM (Cubic Metric: cubic metric) characteristics of the sequence should be guaranteed to a certain extent. This means that the sequences belonging to the set of sequences used for the random access procedure should have correlation or CM properties guaranteed to be greater than a certain level. Specifically, considering the Doppler effect, in order to ensure the characteristics of the sequence, it is necessary to use the sequence for the high-speed environment where the user equipment moves at a speed of 30 km/h or faster and the sequence for the low-speed environment separately.

It is desirable to find a way to guarantee the properties of the sequence used for the transmission of uplink control information with a small amount of signaling overhead.

Contents of the invention

technical problem

Provides a method to generate a logical index of Zadoff-Chu (ZC) root sequences (root ZC sequences) to facilitate sequence generation.

A method of performing a random access procedure in a wireless communication system using a logical index of a ZC root sequence is provided.

A method for generating a random access preamble using a logical index of a ZC root sequence is provided.

Technical solutions

In one aspect, a method of generating a logical index of a Zadoff-Chu (ZC) root sequence is provided, the method comprising the steps of: dividing a plurality of root indexes of a ZC root sequence into one or more according to a predetermined cyclic shift parameter A plurality of subgroups, the subgroups including at least one root index of the ZC root sequence, and mapping the root indices of the ZC root sequences in the subgroups to consecutive logical indices.

In another aspect, a method of performing a random access procedure in a wireless communication system is provided, the method comprising the steps of: selecting a random access preamble from a plurality of random access preambles, the plurality of random access preambles The incoming preamble is generated from the available cyclic shifts of the ZC root sequence with consecutive logical indices mapped to the root index of the ZC root sequence; the selected random access preamble is transmitted , and receiving a random access response including the identifier of the selected random access preamble.

In yet another aspect, a method of performing a random access procedure in a wireless communication system is provided, the method comprising the steps of: transmitting a predetermined cyclic shift parameter and a source logic index for generating a plurality of random access preambles ; receiving a random access preamble selected from the plurality of random access preambles according to the available cyclic shift of the ZC root sequence with the source logical index and the generated from at least one consecutive logical index of the source logical index, and sending a random access response including an identifier of the random access preamble.

In yet another aspect, there is provided a method of generating a random access preamble, the method comprising the steps of: in order of increasing cyclic shifts according to a first ZC root sequence having a first root index mapped to a first logical index generating a random access preamble; and, when a predetermined number of random access preambles cannot be generated according to the first ZC root sequence, according to a second ZC root sequence having a second root index mapped to a second logical index according to A further random access preamble is generated in an order of increasing cyclic shift, the second logical index being consecutive to the first logical index.

In yet another aspect, a method of generating a random access preamble, the method comprising the steps of: receiving information about a source logical index; and based on a sequence of ZC roots having consecutive logical indices starting at said source logical index, The random access preambles are generated in the order of increasing cyclic shift until a predetermined number of random access preambles are obtained, wherein the consecutive logical indices are mapped to the root indices of the ZC root sequence.

Beneficial effect

By utilizing consecutive logical indices, a set of random access preambles with similar physical characteristics can be generated. Control signaling for generating a random access preamble can be minimized. Random access failures can be reduced and efficient cell planning can be performed in this high-speed environment.

Description of drawings

FIG. 1 is an exemplary diagram illustrating a method of performing a random access procedure in a WCDMA system.

FIG. 2 is a diagram illustrating a wireless communication system.

FIG. 3 is a flowchart illustrating processing of a method of generating a sequence according to an exemplary embodiment of the present invention.

FIG. 4 is a graph showing a CM (CubicMetric: cubic metric) characteristic and a maximum supportable cell radius characteristic with respect to a physical root index according to an exemplary embodiment of the present invention.

FIG. 5 is a graph showing a CM characteristic and a maximum supportable cell radius characteristic with respect to a logical root index according to an exemplary embodiment of the present invention.

FIG. 6 is a graph showing a CM characteristic and a maximum supportable cell radius characteristic with respect to a logical root index according to another exemplary embodiment of the present invention.

7 to 14 are graphs illustrating CM characteristics and maximum supportable cell radius characteristics with respect to logical root indexes according to still another exemplary embodiment of the present invention.

FIG. 15 is a graph showing the limited number of cyclic shifts that can be used per Ncs per logical index for CM mapping according to an exemplary embodiment of the present invention.

FIG. 16 is a graph showing the number of limited cyclic shifts that can be used per Ncs per logical index for maximum supportable cell size mapping according to an exemplary embodiment of the present invention.

FIG. 17 is a graph showing the limited number of cyclic shifts that can be used per Ncs per logical index for hybrid mapping according to an exemplary embodiment of the present invention.

FIG. 18 is a diagram illustrating an example of a logical root index allocated to a cell with respect to a CM map according to an exemplary embodiment of the present invention.

FIG. 19 is a diagram illustrating an example of mapping a logical root index allocated to a cell with respect to a maximum supportable cell size according to an exemplary embodiment of the present invention.

FIG. 20 is a diagram illustrating an example of mapping a logical root index allocated to a cell with respect to a maximum supportable cell size according to an exemplary embodiment of the present invention.

FIG. 21 is a diagram illustrating a method of searching a logical root index according to CM characteristics according to an exemplary embodiment of the present invention.

FIG. 22 is a diagram illustrating a method of searching a logical root index according to CM characteristics according to another exemplary embodiment of the present invention.

FIG. 23 is a diagram illustrating a method of searching a logical root index according to CM characteristics according to still another exemplary embodiment of the present invention.

FIG. 24 is a graph showing CM characteristics with respect to physical root indexes according to an exemplary embodiment of the present invention.

FIG. 25 is a graph showing a CM characteristic and a maximum supportable cell radius characteristic with respect to a logical root index according to another exemplary embodiment of the present invention.

FIG. 26 is a graph showing a CM characteristic and a maximum supportable cell radius characteristic with respect to a logical root index according to another exemplary embodiment of the present invention.

FIG. 27 is a diagram showing a process of sorting and grouping CMs into 2 groups.

FIG. 28 is a diagram showing a process of grouping indexes sorted by the maximum supportable Ncs property into Ncs groups in each group.

FIG. 29 is a diagram showing a process of sorting indexes by CM characteristics in each Ncs group.

FIG. 30 is a flowchart illustrating a random access procedure according to an exemplary embodiment of the present invention.

Figure 31 is a schematic block diagram of elements of user equipment to which the exemplary embodiments are applied.

Detailed ways

Figure 2 illustrates a wireless communication system. Such wireless communication systems can be widely deployed to provide various communication services such as voice, packet data, and so on.

Referring to FIG. 2 , a wireless communication system includes a user equipment (UE) 10 and a base station (BS) 20 . The UE 10 may be fixed or mobile, and may be referred to by other terms (e.g., MS (Mobile Station: Mobile Station), UT (User Terminal: User Terminal), SS (Subscriber Station: User Station), wireless equipment, etc.) etc.) . The BS 20 is a fixed station that communicates with the UE 10, and may also be called Node B, BTS (Base Transceiver System: Base Transceiver System), AP (Access Point: Access Point), and the like. There may be one or more cells in the BS 20.

Thereafter, downlink means communication from BS 20 to UE 10, and uplink means communication from UE 10 to BS 20. In the downlink, the transmitter may be part of the BS 20 and the receiver may be part of the UE 10. In the uplink, the transmitter may be part of the UE 10 and the receiver may be part of the BS 20.

There is no limitation with regard to the multiple access techniques used in the wireless communication system. For example, various multiple access technologies (for example, CDMA (Code Division Multiple Access: Code Division Multiple Access), TDMA (Time Division Multiple Access: Time Division Multiple Access), FDMA (Frequency Division Multiple Access: Frequency Division Multiple Access), SC -FDMA (Single Carrier-FDMA: Single Carrier-FDMA) and ODFMA (Orthogonal Frequency Division Multiple Access: Orthogonal Frequency Division Multiple Access)). For clarity, an OFDMA-based wireless communication system is described below.

OFDM uses multiple orthogonal subcarriers. OFDM utilizes the orthogonality between IFFT (Inverse Fast Fourier Transform: Inverse Fast Fourier Transform) and FFT (Fast Fourier Transform: Fast Fourier Transform). The transmitter performs IFFT on the data and sends these data, and the receiver performs FFT on the received signal to recover the original data. The transmitter uses IFFT to combine multiple subcarriers, and the receiver uses corresponding FFT to separate the combined multiple subcarriers. According to OFDM, the complexity of a receiver in a frequency selective fading environment of a wideband channel can be reduced, and spectral efficiency can be improved by performing selective scheduling in the frequency domain by utilizing different channel characteristics of subcarriers. OFDMA is a multiple access scheme based on OFDM. According to OFDMA, different subcarriers can be allocated to multiple users, thereby improving the efficiency of radio resources.

There are various types of control information (for example, ACK (Acknowledgment: Acknowledgment)/NACK (Negative-Acknowledgment) signal indicating whether retransmission should be performed, CQI (Channel Quality Indicator: Channel Quality Indicator) indicating the quality of the downlink channel indicator), a random access preamble for the random access process, and MIMO control signals such as PMI (Precoding Matrix Index: precoding matrix index), RI (Rank Indicator: rank indicator), etc.).

Orthogonal sequences may be used to send control information. Orthogonal sequences refer to sequences with good correlation properties. The orthogonal sequence may include, for example, a CAZAC (Constant Amplitude Zero Auto-Correlation: Constant Envelope Zero Auto-Correlation) sequence.

Regarding the ZC (Zadoff-Chu) sequence (one of the CAZAC sequences), the kth element c(k) of the ZC root sequence (root ZC sequence) corresponding to the root index M can be expressed as:

Mathematical diagram 1

【Formula 1】

$c\left(k\right)=\exp \{-\frac{\mathrm{j\πMk}(k+1)}{N}\},$ for odd N

$c\left(k\right)=\exp \{-\frac{\mathrm{j\π}{\mathrm{Mk}}^2}{N}\},$ For even N

Among them, N is the length of the ZC root sequence, and the root index M and N are mutually prime. If N is a prime number, the number of root indices of the ZC sequence shall be N-1.

The ZC sequence c(k) has the following three properties.

Mathematical diagram 2

【Formula 2】

|c(k)|=1 for all k, N, M

Math Figure 3

【Formula 3】

Mathematical Figure 4

【Formula 4】

${\mathrm{<figure-callout\; id="1"\; label="R\; m"\; filenames="A2008800085940050H2.png"\; state="\{\{state\}\}">R</figure-callout>}}_{m_{}}\left(d\right)=\mathrm{const}$ For all M ₁ , M ₂

Equation 2 indicates that the dimension of the ZC sequence is always 1, while Equation 3 expresses the autocorrelation of the ZC sequence as a Dirac-delta function. Here, autocorrelation is based on circular correlation. Equation 4 indicates that the cross-correlation is always constant.

In a wireless communication system, if it is assumed that the cells are distinguished by the root index of the ZC sequence, the user equipment needs to know the root index or root index group that can be used in the cell, and the base station should broadcast the available root index or the available root index to the user equipment. Root index group.

If the length of the ZC sequence is N, then the number of root indices should be the number of natural numbers smaller than N that are relatively prime to N. If N is a prime number, the number of root indices is N-1. In this case, in order for the base station to notify the user equipment about one of N-1 root indexes, ceil(log ₂ (N-1)) bits are required. ceil(x) represents the smallest integer greater than x.

Each cell may use a different number of root indices according to the cell radius. If the cell radius increases, the number of ZC sequences capable of maintaining orthogonality through cyclic shift decreases due to propagation delay or round-trip delay and/or delay spread. That is, if the cell radius increases, although the length of the ZC sequence is fixed (constant, unchanged), the number of available cyclic shifts in the corresponding root index decreases. Because the sequences generated by cyclic shifting in the root index are orthogonal to each other, they are also called ZCZ (Zero Correlation Zone: Zero Correlation Zone) sequences. The minimum number of ZC sequences allocated to user equipment in each cell should be guaranteed. Therefore, if the cell radius increases, the number of root indices used in each cell also increases to ensure the minimum number of ZC sequences.

Assume that the ZC root index (root ZC indexes) group available in each cell is R _i , and a total of M ZC root index groups are set, which can be expressed as R ₁ , R ₂ , . . . , R _M . If R _i =10, it can be said that the cell set as R _i uses 10 ZC root indexes. According to each cell radius, it is assumed that N=839, M=7, R ₁ =1, R ₂ =2, R ₃ =4, R ₄ =8, R ₅ =16, R ₆ =32 and R ₇ =64. Then, if the cell radius is large, a minimum of 7 bits (ceil(log ₂ (7))+ceil(log ₂ (838/64))=7 bits) is required to send control information, while if the cell radius is small, a maximum of 13 bits (ceil(log ₂ (7))+ceil(log ₂ (838/1))=13 bits) to transmit control information.

With the advancement of wireless communication systems, the demand for higher transmission rates is gradually increasing, and cells with smaller radii are also gradually increasing. Because these cells with small radii only use a single ZC root index, more bits are needed to send control information, which may cause excessive signal overhead. Therefore, a technique for reducing the number of bits required for signal transmission in each cell is required. In particular, reducing the number of signal transmission bits is critical in cells with small cell radii.

FIG. 3 is a flowchart illustrating processing of a method of generating a sequence according to an exemplary embodiment of the present invention.

Referring to FIG. 3, a plurality of ZC root sequences are divided into one or more subgroups according to a predetermined cyclic shift parameter (S110). At least one ZC root sequence is included in the subgroup. If the cyclic shift parameter is Ncs, the ZC root sequence has a zero-correlation zone of length Ncs-1. The cyclic shift parameter is a parameter used to obtain the cyclic shift unit of the ZC root sequence, and the subgroups can be sorted according to the cyclic shift parameter. Because the Doppler effect is strong in a high-speed environment, the cyclic shift unit is obtained by using the cyclic shift parameter according to the maximum supported cell radius and the Doppler frequency shift in the detection stage. The cyclic shift unit is a unit used to cyclically shift the ZC root sequence. The cyclic shift parameter of the ZC root sequence is less than or equal to a predetermined cyclic shift parameter of the subgroup of the ZC root sequence. The value of the cyclic shift of the ZC root sequence is greater than the cyclic shift parameter of the ZC root sequence.

Sort the ZC root sequence according to CM (Cubic Metric: cubic metric) in the subgroup. Sorting the ZC root sequence according to the CM characteristic refers to sorting the ZC root sequence according to the combination of the ZC root index and according to the CM characteristic of the ZC sequence. Cross-correlation, PAPR (Peak-to-Average Power Ratio: Peak-to-Average Power Ratio), Doppler frequency, etc., and CM can be used as metrics for ordering ZC root sequences in subgroups. Sorting according to the cross-correlation property refers to sorting the ZC root sequence according to the cross-correlation property of the ZC sequence according to the combination of the ZC root indexes. Sorting according to the PAPR characteristic refers to sorting the ZC root sequence according to the PAPR characteristic of the ZC sequence according to the combination of the ZC root index. The sorting according to the Doppler frequency characteristic refers to sorting the ZC root sequences according to the robustness of the root index to the Doppler frequency.

In relatively high-mobility cells or high-speed cells, a root index with a robust Doppler frequency can be used to gain gain. When restricted cyclic shift is used in a high mobility cell, the root indices of the ZC root sequence may be sorted (or grouped) according to the maximum supportable cell radius or the maximum supportable cyclic shift characteristic. By comparing the maximum supportable cyclic shift parameter of each ZC root cyclic sequence with a predetermined cyclic shift parameter, the root index of the ZC root sequence can be divided into subgroups, so that the ZC root sequences of each subgroup can have similar characteristic.

The physical root indexes of the ZC root sequences belonging to a subgroup are mapped onto consecutive logical indexes (S130). The physical root index refers to the root index of the ZC sequence actually used by the base station and/or user equipment to send control information or random access preamble. The logical index refers to the logical root index to which the physical root index is mapped.

As mentioned above, when the ZC root sequence is divided into subgroups according to a predetermined cyclic shift parameter, and consecutive logical indexes are allocated to the subgroups, the base station may only notify the user equipment of at least one logical index to provide information about Information on multiple ZC sequences. For example, assume that ZC root sequences are sorted according to CMs in subgroups, and a single logical index is notified to the user equipment. Then, the user equipment generates a ZC root sequence according to the physical root index to which the received single logical index is mapped. If the number of ZC sequences generated according to a single logical index (for example, the number of cyclic shifts available for the ZC sequence) is insufficient, the user equipment generates a new ZC root sequence. Since adjacent (contiguous) logical indices have similar CM properties, even if only one logical index is given, the user equipment can generate multiple ZC sequences with similar CM properties.

<Example of sorting by CM property>

FIG. 4 is a graph showing a CM (CubicMetric: Cubic Metric) characteristic and a maximum supportable cell radius characteristic with respect to a physical root index according to an exemplary embodiment of the present invention. FIG. 5 is a graph showing logical root indexes corresponding to CM characteristics and maximum supportable cell radius characteristics according to an exemplary embodiment of the present invention. Fig. 6 is a graph showing logical root indexes corresponding to CM characteristics and maximum supportable cell radius characteristics according to another exemplary embodiment of the present invention.

If "N" is the length of the ZC sequence, the physical root index in FIG. 4 can be expressed as U _p =1, 2, 3, ..., N-3, N-2, N-1. Fig. 5 shows alternately picking physical root indices one by one from the start and end, and reordering them as U _p = 1, N-1, 2, N-2, 3, N-3, 4... The result obtained. FIG. 6 shows the result obtained by sorting the physical indices in FIG. 4 into CM values corresponding to the logical indices.

Table 1 shows an example of sorting physical root indexes and logical indexes based on CM.

Table 1

【Table 1】

Since physical root indexes are sorted according to CM characteristics and then mapped onto logical indexes, it is possible to maintain CM characteristics of ZC sequences corresponding to consecutive logical indexes as well, and it is possible to perform CM-based cell planning. The base station can plan a CM-based cell in a power-limited environment (such as a cell with a bad channel environment or a cell with a large cell radius). Also, the base station can use an index with good CM characteristics as a dedicated preamble for handover and the like. A user equipment in a harsh channel environment has already used its maximum power, therefore, it hardly obtains a power ramping effect. Therefore, the base station can allocate an index with good CM characteristics to the user equipment to improve the detection probability.

<Example of sorting based on maximum supportable cell radius characteristics>

FIG. 7 is a graph showing CM characteristics and maximum supportable cell radius characteristics with respect to a physical root index according to another exemplary embodiment of the present invention. FIG. 8 is a graph illustrating a CM characteristic and a maximum supportable cell radius characteristic with respect to a logical root index according to another exemplary embodiment of the present invention. FIG. 9 is a graph illustrating a CM characteristic and a maximum supportable cell radius characteristic with respect to a logical root index according to another exemplary embodiment of the present invention.

Referring to FIG. 7 to FIG. 9, FIG. 7 shows the sorting of the ZC sequences used in FIG. 4 according to the maximum supportable cell radius. If "N" is the length of the ZC sequence, then by (1/U _p ) mod N to the physical root index U _p in Figure 7 =1, 2, 3, ..., N-3, N-2, N- 1 for reordering. In this case, performing (1/U _p ) mod N on the ZC sequence index generated in the time domain means mapping the ZC sequence index generated in the time domain to the ZC sequence index generated in the frequency domain. In other words, this conversion refers to reordering the properties of the ZC-sequence indices generated in the time domain to the ZC-sequence indices generated in the frequency domain. Figure 8 shows alternately picking the indices that have been converted from the physical index U _p to (1/U _p ) mod N from the beginning and the end one by one, and reordering them as 1, N-1, 2, N-2, 3, N-3, 4... and the results obtained. FIG. 9 shows the results obtained by precisely reordering according to the maximum supportable cell radius corresponding to the physical index.

Table 2 shows an example of sorting based on the maximum supportable cell radius.

Table 2

【Table 2】

The method of reordering according to the maximum supported cell radius can be applied to the case of using limited cyclic shift in a high-speed cell environment. In the use-limited cyclic shift, the value of the supportable cyclic shift parameter Ncs may vary according to the index. If the physical root index shown in FIG. 4 is used as it is, it is difficult to use consecutive physical indexes in a single cell. Therefore, non-repetitive indexes for each cell should be allocated in the entire network, but this may cause the following problem: the reuse factor of the sequence is reduced and cell planning is difficult. This problem can be solved by using a logical index sorted by the characteristic of the largest supportable cell radius, but this kind of sorting by the characteristic of the largest supportable cell radius may not be able to obtain gains in CM characteristics.

<Example of sorting based on CM characteristics and maximum supportable cell radius characteristics>

The sorting according to the CM characteristic has opposite characteristics to the sorting according to the maximum supportable cell radius characteristic. A method for realizing the gain of both the CM characteristic and the maximum supportable cell radius characteristic is introduced below.

The sorting method by combining different properties follows the steps below.

Step 1. Sort the entire index according to a specific (special) characteristic.

Step 2. Divide the entire index into sections (groups) based on related values (grouping).

Step 3. Sorting the indexes of the sections in each section (group) according to their different characteristics.

Step 4. Repeat steps 2 and 3. In this case, when dividing the index into sections, the subsequent section may have an association with the preceding section, or the subsequent section may not have any association with the preceding section, At the same time, new criteria can be applied to the subsequent section.

FIG. 10 is a graph showing a CM characteristic and a maximum supportable cell radius characteristic with respect to a logical root index according to still another exemplary embodiment of the present invention. That is to say, FIG. 10 shows the sorting according to the characteristics of the maximum supportable cell radius and the section of the maximum supportable cell radius set according to the special value Ncs (predetermined cyclic shift parameter). FIG. 11 is a graph showing sorting according to CM characteristics within the setting section of FIG. 10 .

Referring to FIG. 10 and FIG. 11 , firstly, the entire index is sorted according to the maximum supportable cell radius, and the entire index is divided into (multiple) sections according to the cyclic shift parameter Ncs or the maximum supportable cell radius value. The cyclic shift parameter Ncs is used to obtain the cyclic shift unit supported by each ZC sequence.

Table 3 shows an example of the cyclic shift parameter Ncs.

table 3

【table 3】

If the physical index has such characteristics as shown in FIG. 4 , then as shown in FIG. 9 , the entire index can be sorted according to the maximum supportable cell radius. The results shown in Fig. 10 are obtained when the sector(s) are divided by the maximum supportable cell radius value with respect to the cyclic shift parameter Ncs. Here, the value of "unprotected sampling" is used.

When the root indexes were sorted according to the CM characteristics in each divided section, the result shown in FIG. 11 was obtained. In this case, a hybrid ordering considering both CM and maximum supportable cell radius is applied in the mapping from physical index to logical index (shown in Figure 4).

Table 4

【Table 4】

Multiple sequences are divided into multiple subgroups according to a predetermined cyclic shift parameter Ncs, and sorting is performed in each subgroup according to CM characteristics. The plurality of subgroups are sorted according to each corresponding cyclic shift parameter. The largest peak (or the smallest peak) appearing in the upper part of the graph as shown in FIG. 11 indicates the root index of each subgroup having the largest CM (or the smallest CM).

Each cell can use continuous logical indexes without considering the cell size by hybrid sorting according to cyclic shift parameters and CM characteristics, and can perform CM-based cell planning according to the characteristics of each cell. For user equipment in a special power-limited environment in each cell, the base station can use the smallest logical index allocated to the base station itself. For example, the base station may use the smallest logical index as a dedicated preamble for the user equipment performing handover. In the smallest cell size interval, the supportable cell size is very small, and there may be an index with a value smaller than 0 km. Such an index represents an index that cannot use restricted cyclic shifts. Furthermore, the extent(s) can be further divided to simplify index allocation. In Fig. 11, the first segment is divided into 0-1.1 km, but this segment can be divided into smaller parts and sorted based on CM. For example, the first section can be divided into two parts of 0-500m and 500m-1.1km and the first section can be sorted based on CM.

Table 5 shows physical indexes of Ncs sections according to settings.

table 5

【table 5】

Table 5 shows that multiple physical root indexes are divided into multiple subgroups according to a predetermined cyclic shift parameter Ncs, and continuous logical indexes are allocated in each subgroup.

Using such a set of logical indexes makes it possible to easily select a sequence according to the cell size in a cell with high mobility. Also, if a cell requires low CM characteristics, it can simply select the previous index among the indexes that can be used for the cell size, thereby using an index with low CM characteristics. Table 5 is not meant to use only index values (physical or logical) related to Ncs. In a cell of low/medium mobility an index suitable for the CM characteristic of the cell may be selectively used regardless of the cell size. In addition, an Ncs section table that can be used in a cell of low/medium mobility can be set separately. In this case, the table to be applied may be selected using a distinguishing signal of a cell with low/medium mobility and a cell with high mobility.

FIG. 12 is a graph showing CM characteristics and maximum supportable cell radius characteristics with respect to a logical root index according to still another exemplary embodiment of the present invention. That is, Figure 12 shows sorting based on various characteristics as well as pair allocation.

Referring to FIG. 12 , the ZC sequence has a property of complex conjugate symmetry, and based on this, indices having complex conjugate symmetry can be assigned consecutively in pairs.

The complex conjugate symmetry of the ZC sequence can be expressed as follows:

Mathematical Figure 5

【Formula 5】

${\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; a</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>$

Among them, (.) ^* represents complex conjugate. The sum of the two root indices of two ZC sequences with complex conjugate symmetry is equal to the length of the ZC sequences. This property cannot be obtained if only a single root index is used in a cell, but in case of using multiple root indices with complex conjugate symmetric properties, the complexity of the receiver's detector can be halved. While applying CM-based sorting, maximum supportable cell radius-based sorting, hybrid sorting, etc. to the root index, root indices having complex conjugate symmetry properties can be continuously assigned. When assigning indexes in pairs, the base station notifies only a single logical index, and the user equipment naturally uses paired indexes when increasing the logical index as needed.

In the above Table 5, each group includes an odd number of indices, and in order to constitute a complex conjugate symmetric property, a lower group can use an index in a higher group, which can be expressed as shown in Table 6.

Table 6

【Table 6】

The result of constituting complex conjugate symmetry properties looks similar to that of the hybrid ordering of Fig. 11. That is, indexes can be ordered so that they can be allocated in pairs without reducing their special properties.

FIG. 13 is a graph showing CM characteristics and maximum supportable cell radius characteristics with respect to a logical root index according to another exemplary embodiment of the present invention. That is, FIG. 13 shows sorting based on various characteristics as well as pairwise assignments.

Referring to FIG. 13 , the sections divided in FIG. 12 can be divided more finely. For example, the segments of configuration numbers 11 and 12 of Table 3 may be halved to use a wider maximum cell radius.

Table 7 shows a mapping table of physical indexes of respective sectors when the 11th and 12th sectors are halved.

Table 7

【Table 7】

The maximum cell radius can be increased from 29.14km to 34.15km to be used by applying Table 7. Here, the special section is bisected and reordered, but this is only an example. That is, the size of the special section can be divided in various ways. For example, to support a special maximum cell radius, segments may be divided based on the special maximum cell radius. Alternatively, segments can be divided in such a way that the number of indexes used for a particular segment is doubled. Segments with a small number of indexes can be grouped into a segment to which a second sort can be applied. Additionally, segments with a large number of indexes can be grouped into two (or more) segments, to which a second sort can be applied.

FIG. 14 is a graph showing CM characteristics and maximum supportable cell radius characteristics with respect to a logical root index according to another exemplary embodiment of the present invention. That is, FIG. 13 shows that indexes are divided into groups based on CM characteristics and sorted by the maximum supportable cell size in each group.

Referring to Figure 14, first, the indexes can be sorted according to the CM characteristics, and divided into groups with CM higher than 1.2dB (i.e., QPSK CM) and groups with lower CM, and then, in each group, according to the largest supportable cell Sort by radius. Indexes in groups with CMs lower than QPSK may be sorted in order of decreasing maximum supportable cell size, and indices in groups with CMs higher than QPSK may be sorted in order of increasing maximum supportable cell size.

Table 8 is a mapping table according to the physical index of the section under the following conditions, sort the index according to the CM characteristic, and group the index based on 1.2dB (single CM value), and then in each group according to the largest possible Support cell size sorting.

Table 8

【Table 8】

<Comparison of multiplexing factors in large cells>

FIG. 15 is a graph showing the limited number of cyclic shifts that can be used per Ncs per logical index for CM mapping according to an exemplary embodiment of the present invention. FIG. 16 is a graph showing the number of limited cyclic shifts that can be used per Ncs per logical index for maximum supportable cell size mapping according to an exemplary embodiment of the present invention. FIG. 17 is a graph showing the limited number of cyclic shifts that can be used per Ncs per logical index for hybrid mapping according to an exemplary embodiment of the present invention.

Referring to FIGS. 15 to 17 , compared with CM mapping, maximum supportable cell size mapping and hybrid mapping may use consecutive indexes in high-speed cells. For example, suppose there are 20 cells, the cyclic shift parameter Ncs of the first cell is 13, the Ncs of the next 2 cells (ie, the 2nd cell and the 3rd cell) is 26, and the Ncs of the next 3 cells are 38, the Ncs of the next 4 plots is 38, the Ncs of the next 4 plots is 52, and the Ncs of the next 4 plots is 64. In this case, pairwise index assignments are applied to the individual maps. Ncs represents the number of cyclic shifts according to cell size. Referring to Figure 13, it should be noted that the middle part is 0 and no limited cyclic shift is available. In contrast, referring to Figures 15 and 16, no restricted cyclic shifts are available. That is, consecutive indexes cannot be used for CM mapping but can be used for maximum supportable cell size mapping and hybrid mapping.

FIG. 18 is a diagram illustrating an example of a logical root index assigned to a cell with respect to a CM map according to an exemplary embodiment of the present invention. FIG. 19 is a diagram illustrating an example of a logical root index allocated to a cell with respect to a maximum supportable cell size map according to an exemplary embodiment of the present invention. FIG. 20 is a diagram illustrating an example of mapping a logical root index allocated to a cell with respect to a maximum supportable cell size according to an exemplary embodiment of the present invention. That is, FIGS. 18 to 20 show which indexes are allocated to cells based on the assumptions of FIGS. 15 to 17 .

18 to 20, it is assumed that each cell has high-speed mobility. Referring to FIG. 18, it should be noted that consecutive indexes are not used in large cells. In contrast, referring to Figures 19 and 20, it should be noted that consecutive indices can be used in large cells. In FIG. 19 and FIG. 20, if the Ncs of one cell is 209 (Ncs=209), four cells with Ncs of 167 (Ncs=167) can be constructed. The reason for this is that consecutive indexes cannot be used in FIG. 18 . More importantly, it should be noted that in Fig. 18, if the Ncs of one cell is 209 and the Ncs of 3 cells are 167, then no district. For comparison, in FIG. 19 and FIG. 20 , cells of various sizes can be constructed. Also, it should be noted that in FIG. 18, multiple indices have a value of 0 at the y-axis and cannot be used for cells moving at high speed. While those indices can be used when high mobility cells are mixed with only one low mobility cell, such indices greatly reduce the cell construction capability. Therefore, the inability to use these consecutive indices greatly reduces the reuse factor when there are multiple large cells. That is, by using consecutive indices, different cells can use additional space. Using consecutive indexes does not make a big difference in a network that includes only small cells, but for networks that include multiple large cells, supporting the use of consecutive indexes can increase the reuse factor. 18 to 20 consider the case of having high-speed mobility in each cell, but even when there are cells with low-speed mobility or medium-speed mobility, if consecutive indexes cannot be used for the same reason, then It also makes the reuse factor limited. Likewise, if consecutive indices are used in cells with low or medium mobility, the reuse factor for cells with high mobility will be further restricted.

Table 9, Table 10 and Table 11 show the precise index used by each mapping. Table 9 shows the index for CM mapping, Table 10 shows the index for the maximum supportable cell size mapping, and Table 11 shows the index for hybrid mapping, in Table 9 and Table 10, in turn Physical root indexes with respect to logical indexes 1 to 838 are set.

Table 9

【Table 9】

Table 10

【Table 10】

<Supported cell size sorting and CM classification>

FIG. 21 is a diagram illustrating a method of searching a logical root index according to CM characteristics according to an exemplary embodiment of the present invention. FIG. 22 is a diagram illustrating a method of searching a logical root index according to CM characteristics according to another exemplary embodiment of the present invention. FIG. 23 is a diagram illustrating a method of searching a logical root index according to CM characteristics according to still another exemplary embodiment of the present invention.

Referring to FIGS. 21 to 23 , physical indexes are first sorted according to supportable cell sizes. Thereafter, a method of using available indexes in each cell varies according to characteristics of a single transmitted index. The allocation of logical indexes may be formed according to one logical index+Ncs. This can be achieved by the following 2 methods.

In one approach, each cell uses only a single sequence class (see Figure 20), which is divided into low and high CM indices.

If the transmitted logical index has CM characteristics lower than or equal to QPSK CM (1.2dB) of SC-FDMA, then search and use the nearest adjacent logical index with CM characteristics lower than or equal to QPSK CM of SC-FDMA . If the transmitted logical index has a CM characteristic higher than QPSK CM of SC-FDMA, the nearest adjacent logical index having a CM characteristic higher than QPSK CM of SC-FDMA is sequentially searched for and used.

In another approach, a single cell can use either of the sequence classes (lower CM or higher CM) (see Figures 20 and 21). It is divided into lower CM index, higher CM index and mixed CM index.

If the transmitted logical index has CM characteristics lower than or equal to QPSK CM (1.2dB) of SC-FDMA, then search and use the nearest adjacent logical index with CM characteristics lower than or equal to QPSK CM of SC-FDMA . In this case, when the end of one Ncs segment is reached, the index is reset to the index of the first higher CM with the next Ncs segment. If the transmitted logical index has a CM characteristic higher than QPSK CM (1.2dB) of SC-FDMA, the nearest adjacent logical index having a CM characteristic higher than QPSK CM of SC-FDMA is sequentially searched for and used. In this case, when the end of one Ncs segment is reached, the index is reset to the index of the first lower CM with the next Ncs segment.

The direction (+/-, the direction in which the index increases/decreases) for searching the index with the same characteristic may be the same or different. Similar to the sorting direction (ascending/descending) of the index described above, the direction used to search the index does not affect the proposed technique.

FIG. 24 is a graph showing CM properties with respect to physical root index according to an exemplary embodiment of the present invention.

Referring to FIG. 24, a sequence class may be defined in terms of physical indexes. The physical root index can be classified by setting the CM classification threshold. Classification of the physical root index can be performed simply by checking whether the selected physical index belongs to a high-CM region or a low-CM region. For example, it can be noticed that if the threshold for CM classification is 1.2dB, high CM regions can be determined as [238, Nzc-238]. Using this method makes it possible to generate indexes by simple numerical calculation formulas to sort indexes (or index maps) without complicated tables.

The mapping of the physical index U phy (U _log ) in response to the logical _index U _log based on the maximum supportable cell size (or Ncs) can be expressed as:

Mathematical Figure 6

【Formula 6】

${\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; plty</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; u</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>& \mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1,2,3</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1,2</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 139</span>}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>& \mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1,2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 140</span>}\end{array}\right.$

u _plty (2·i)=N _ZC −u _plty (2·i−1), i=1, 2, . . . , (N _ZC −1)/2

where α _i,1 =(N _ZC +1), α _i,2 =2i-1, α _i,3 =2i and u'(r)=(-1/r) mod N _ZC

                             

An example of selecting adjacent available indices when multiple indices are used in a cell can be expressed as:

Mathematical Figure 7

【Equation 7】

Wherein, U _log ++ represents the next logical index associated with U _log (for example, U _log + 1, U _log +2, U _log +3, . . . ) and I _t =238. In this case, all indexes are searched in the positive (+) direction (that is, in the direction in which the index increases). If mixed CM indexes are not allowed, the search process is simpler. When the low CM sequence reaches the boundary of Nzc-1 through U _log ++ process, this U _log ++ is set as the first logical index of U _log ++. However, some conditions are required if mixed CM indexes are allowed. If U _log ++ reaches the boundary of the Ncs sequence, then the U _log ++ is reset to the first logical index in the U _log ++Ncs segment. If U log++ reaches the boundary of an Ncs segment during U _log ++ processing for a higher CM, reset U _{log ++} to the first logical index of the next Ncs segment. In this case, as for the CM characteristics when U _log ++ is reset, if mixing CM indices is not allowed, then U _log ++ can be reset to the first CM with the same characteristics as the transmitted index an index. Whereas if mixed CM indices are allowed, U _log ++ can be reset to a higher or lower CM that has been previously determined from the nature of the indices sent.

Another example of selecting adjacent available indices when multiple indices are used in a cell can be expressed as:

Numeral Figure 8

【Formula 8】

Wherein, U _log ++ represents the next logical index associated with U _log (for example, U _log +1, U _log +2, U _log +3, . . . ) and I _t =238. In this case, indexes are searched in positive (+) and negative (-) directions (that is, in directions in which the index increases or decreases).

If it is difficult to use a numerical calculation formula to express the ordering of indexes, each base station and each user equipment should have a large ordering table of 838*10 bits (1-838)=8380 bits. However, if Equation 6 is given, each base station and each user equipment can be sorted using the maximum supportable cell size without such a sorting table. Table 12 shows the mapping from physical index to logical index based on the maximum supportable cell size using Equation 6.

Table 12

【Table 12】

In all the exemplary embodiments described above, when the indexes are sorted based on a certain property, the order of values with the same property does not affect the order of sorting. Likewise, the order of pairwise indexes does not affect the order of sorting. In the sorting (mapping) method according to all the exemplary embodiments, as the index increases, the indices are sorted in ascending order of increasing CM or maximum supportable cell size, but this is only an example. That is, as the index increases, the indexes may be sorted in each group in ascending order of increasing CM or maximum supportable cell size or in descending order of decreasing CM or maximum supportable cell size. In addition, the index can be sorted by the shape of the peak (^) or by the shape of the valley (v). Meanwhile, directivity of CM or maximum supportable cell size may be determined to be different in each group.

FIG. 25 is a graph showing a CM characteristic and a maximum supportable cell radius characteristic with respect to a logical root index according to another exemplary embodiment of the present invention. As the logical index increases, these indices may be sorted in ascending order of increasing maximum supportable cell size or in descending order of decreasing CM. FIG. 26 is a graph showing a CM characteristic and a maximum supportable cell radius characteristic with respect to a logical root index according to another exemplary embodiment of the present invention. The respective CM groups have been grouped based on the cyclic shift parameter Ncs. As the logical index increases, these indices are sorted in ascending order of increasing maximum supportable cell size, in descending order of decreasing odd group of CMs, and in ascending order of increasing even group of CMs.

Referring to FIGS. 25 and 26 , directivity of CM or maximum supportable cell size may be determined to be different in each group. After sorting the indexes in ascending order of increasing maximum supportable cell size, when sorting the indexes in descending order of decreasing CM, the result shown in FIG. 25 is presented. When the odd groups are sorted in descending order of CM decrease, and the even groups are sorted in ascending order of CM increase, the result shown in FIG. 26 is presented. By making the ordering different in adjacent (contiguous) groups, a large number of adjacent (contiguous) indices with low CM can be used for low mobility cells without regard to the maximum supportable cell radius.

In all the exemplary embodiments described above, if a single index is allocated in each cell according to the sorting (mapping) method, each user equipment can add 1 to the transmitted index or subtract 1 from the transmitted index ( That is, the index is used by incrementing or decrementing by 1) each time as needed to satisfy the required number of random access preambles per cell. When using an index by adding 1 every time, when the largest index 838 is used, it is possible to return to the smallest index 1 and use it. When the index is used by decrementing 1 each time, when the smallest index 1 is used, it is possible to return to the largest index 838 and use it. Also, the direction of growth (+/-) may be used differently according to each characteristic (eg, lower CM/higher CM). When the indexes are sorted in an ascending order in which the maximum supportable cell size increases as the index increases, since indexes available in large cells are limited, it is preferable to allocate indexes starting from large cells. In this case, the simplest method of cell planning is to assign the largest index to the largest cell, and then use the index piecewise by subtracting 1 each time.

<Implementation of Hybrid Sort>

FIG. 27 is a diagram showing a process of grouping CM rankings into two groups. FIG. 28 is a diagram showing a process of grouping indexes sorted by the maximum supportable Ncs property into Ncs groups in each group. FIG. 29 is a diagram showing a process of sorting indexes by CM characteristics in each Ncs group.

Referring to FIGS. 27 to 29 , (1) Sort indexes according to CM characteristics. Divide the indices into groups above 1.2dB (QPSK CM for SC-FDMA) and below 1.2dB (as shown in Figure 27).

(2) After sorting the entire index according to the maximum cell radius, divide the index into segments according to the Ncs value (or the maximum supportable cell radius value). After sorting the groups by the maximum supportable cell radius, these groups are divided into segments with the maximum supportable cell radius value relative to Ncs. In this case, the plurality of groups can be grouped entirely into different groups according to the Ncs value, several special Ncs values can be partitioned into groupings, or a special Ncs value can be further divided. Here, taking the case of using a group corresponding to each Ncs value, the divided sections are as shown in FIG. 28 .

(3) As shown in FIG. 29 , indexes are sorted according to CM characteristics in each divided section. Here, 13, 15, 18, 22, 26, 32, 38, 46, 59, 76, 119, 167, 237, 279, and 419 are used as the Ncs sample values. Table 13 shows the relationship between physical indexes and logical indexes according to the results of FIG. 29 .

Table 13

【Table 13】

In Table 13, there are groups with only a few indexes. Such groups with only a few indexes can be combined with adjacent groups to form a single group.

In all the exemplary embodiments described above, in the case of pairwise assignment, the relative position of two adjacent pairwise indices does not affect the proposed technique. Furthermore, when the indices are sorted by a certain property (eg, CM, maximum supportable cell size (or Ncs, etc.)), the ordering of indices with similar properties does not affect the proposed technique.

In using the above method, the user equipment and the base station should have a mapping table showing the relationship between the physical index and the logical index in each memory. In this case, it is possible to store all 838 indices in each memory or only half of them according to pair-wise allocation. If you only save half, you can assume that the (N-i)th index comes after the i'th index for processing.

When the above-mentioned method is used to sort the indexes and notify the base station of the indexes available in the cell, a method of notifying the number of Ncs configurations and a single logical index can be used. In this case, logical indices 1 to 838 may be notified to a single logical index with 10 bits. Alternatively, the indices 1 to 419 may be notified by using only one value allocated in pairs with 9 bits. In this case, for separate use of pairwise allocation, an additional 1 bit may be used to indicate whether the index used is the front index 1 to 419 or the rear index 420 to 838 in the pairwise allocation. When the index is notified with only 9 bits, processing can be performed on the assumption that the (N-i)th index immediately follows the i-th index.

FIG. 30 is a flowchart illustrating a random access procedure according to an exemplary embodiment of the present invention.

Referring to FIG. 30, a user equipment (UE) receives random access information from a base station (BS) (S310). The random access information includes information on the cyclic shift parameter Ncs and information on generating a plurality of random access preambles. The cyclic shift parameter Ncs is used to obtain the value of the cyclic shift of the ZC root sequence. Information on generating a random access preamble is information on logical indexes. The logical index is the index to which the physical root index of the ZC root sequence is mapped. The logical index is the source index of the set generating the random access preamble.

Information about the cyclic shift parameter Ncs and the logical index can be broadcast as part of the system information or sent in the downlink control channel. There is no limitation on the method or format of sending the cyclic shift parameter Ncs or logical index.

The user equipment obtains a physical root index mapped from the logical index (S320). There are 64 preambles available in each cell. The set of 64 preamble sequences in a cell is solved by first including all available cyclic shifts of the Zadoff-Chu root sequence with that logical index, in order of increasing cyclic shifts. When 64 random access preambles cannot be generated from a single Zadoff-Chu root sequence, additional preamble sequences are obtained from root sequences with consecutive logical indices until all 64 sequences are found. The order of the logical root sequence is cyclic: when Nzc=838, logical index 0 is connected after 837. Therefore, the user equipment can find each available random access preamble by a single logical index.

Even if the base station only informs the user equipment of a single logical index, the user equipment can find the available 64 random access preambles. Furthermore, ZC root sequences corresponding to consecutive logical indices have similar properties, and all generated sequences have substantially similar properties. Likewise, the ZC root sequence corresponding to consecutive logical indices may be complex conjugate symmetric, which means that the sum of the two root indices of the ZC root sequence corresponding to two consecutive logical indices is equal to the length of the ZC root sequence.

After the physical root indexes are sorted according to the subgroups according to the CM, the logical indexes can be sequentially mapped to the physical root indexes of the ZC root sequence. Subgroups are obtained by grouping ZC sequences according to predetermined cyclic shift parameters. Even if a continuous logical index is selected, a ZC root index having characteristics similar to those of an existing logical index can be obtained. Therefore, with only a single logical index, the user equipment can obtain the 64 preamble sequences required for selecting a random access preamble.

As described above, a logical index is an index to which a physical index is mapped in a state where ZC sequences have been grouped into subgroup(s) according to a predetermined cyclic shift parameter and sorted by CM in each subgroup. Therefore, logical sequences belonging to a single subgroup have the same cyclic shift parameter. Although the base station only allocates logical sequences considering the mobility of the user equipment, the user equipment can obtain multiple ZC sequences with the same cyclic shift parameter Ncs and CM-like characteristics.

The user equipment sends the selected random access preamble to the base station on RACH (Random Access Channel: random access channel) (S330). That is, the user equipment randomly selects one of 64 available random access preambles and transmits the selected random access preamble.

The base station transmits a random access response as a response to the random access preamble (S340). The random access response may be a MAC message configured in MAC (higher layer of the physical layer). The random access response is sent in DL-SCH (Downlink Shared Channel: Downlink Shared Channel). The random access response is addressed by RA-RNTI (Random Access-Radio Network Temporary Identifier: Random Access-Radio Network Temporary Identifier) sent on PDCCH (Physical Downlink Control Channel: Physical Downlink Control Channel). RA-RNTI is an identifier for identifying time/frequency resources used for random access. The random access response may include timing alignment information, initial uplink grant and temporary C-RNTI (Cell-Radio Network Temporary Identifier: Cell-Radio Network Temporary Identifier). Timing adjustment information refers to timing correction information for uplink transmission. The initial uplink grant is ACK/NACK information for uplink transmission. Temporary C-RNTI refers to a non-permanent user equipment identifier before conflict resolution.

The user equipment performs scheduled uplink transmission on the UL-SCH (S350). If there is data additionally transmitted as needed, the user equipment performs uplink transmission to the base station and performs a collision resolution process.

If an error occurs in the transmission of the random access preamble, the random access procedure is delayed. Because the random access process is performed when the base station is initially accessed or during the switching process of the base station, the delay in the random access process may cause access delay or service delay. The user equipment can obtain 64 preamble sequences suitable for a high-speed environment, so that the user equipment can reliably send a random access preamble in a high-speed environment.

By utilizing consecutive logical indices, a set of random access preambles with similar physical properties can be generated. Control signaling to generate a random access preamble can be minimized. It is possible to reduce random access failures and perform efficient cell planning in a high-speed environment.

Fig. 31 is a schematic block diagram of elements of a user equipment to which an exemplary embodiment is applied.

The user equipment 50 may include a processor 51 , a memory 52 , an RF unit 53 , a display unit 54 and a user interface unit 55 . The processor 51 can handle the generation and mapping of sequences, and implement the functions related to the various exemplary embodiments described above. The memory 52 may be connected to the processor 51 and store an operating system, application programs and files. The display unit 54 can display various information and utilizes known elements such as LCD (Liquid Crystal Display: Liquid Crystal Display), OLED (Organic LightEmitting Diodes: Organic Light Emitting Diodes), and the like. The user interface unit 55 can be formed by combining user interfaces such as a keypad, a touch screen, and the like. The RF unit 53 is coupled with the processor 51 and transmits or receives wireless signals.

The above-mentioned various components can be executed by a processor (such as a microprocessor based on software coded to perform such a function, program code, etc.), a controller, a microcontroller, an ASIC (Application Specific Integrated Circuit: Application Specific Integrated Circuit), etc. Function. It is obvious that those skilled in the art can design, develop and implement these codes based on the specification of the present invention.

Although the embodiments of the present invention have been disclosed for illustrative purposes, it will be understood by those skilled in the art that various modifications, additions and substitutions may be made thereto without departing from the scope of the present invention. Therefore, the embodiments of the present invention are not limited to the above-described embodiments, but are defined by the appended claims and all scopes of equivalents thereof.

Claims (26)

1, a kind of method of logic index of generation Zadoff-Chu (ZC) root sequence, this method may further comprise the steps:

According to predetermined cyclic shift parameter, a plurality of index of ZC root sequence are divided into one or more height groups, this child group comprises at least one root index of ZC root sequence; And

The root index of the ZC root sequence in the described son group is mapped to continuous logic index.

2, method according to claim 1, wherein, ZC root sequence has the zero correlation block of length for (the cyclic shift parameter value-1 of ZC root sequence).

3, method according to claim 1, this method is further comprising the steps of:

Before being mapped to the logic index, sort according to a kind of root index of measuring the ZC root sequence in the antithetical phrase group.

4, method according to claim 3, wherein, described measuring is cubic measure (CM).

5, method according to claim 1, this method is further comprising the steps of:

Utilize the value of cyclic shift that ZC root sequence is carried out cyclic shift, wherein, the value of this cyclic shift is to utilize the cyclic shift parameter of described ZC root sequence and the Doppler frequency shift of detection-phase to try to achieve.

6, method according to claim 5, wherein, the cyclic shift parameter of described ZC root sequence is less than or equal to the pre-cyclic shift parameter of the child group of described ZC root sequence.

7, method according to claim 5, wherein, the value of the cyclic shift of described ZC root sequence is greater than the cyclic shift parameter of described ZC root sequence.

8, method according to claim 1, wherein, k the element c (k) of ZC root sequence limited by following formula:

$c\left(k\right)=\exp \{-\frac{\mathrm{j\&pi;Mk}(k+1)}{N}\},$ For odd number N

$c\left(k\right)=\exp \{-\frac{\mathrm{j\&pi;}{\mathrm{Mk}}^2}{N}\},$ For even number N

Wherein, N is the length of ZC root sequence, and M is a physics root index, and M and N are relatively prime.

9, method according to claim 1, this method is further comprising the steps of:

According to predetermined cyclic shift parameter described son group is sorted.

10, method according to claim 1, wherein, first logic index of last the logic index of the first son group and the second son group is continuous, and the described second sub-group is continuous with the described first son group.

11, a kind of method of in wireless communication system, carrying out random access procedure, this method may further comprise the steps:

From a plurality of random access lead codes, select a random access lead code, these a plurality of random access lead codes are that the available cycles displacement according to the ZC root sequence with continuous logic index generates, wherein, described continuous logic index is mapped to the root index of described ZC root sequence;

Send selected random access lead code; And

Reception comprises the accidental access response of the identifier of selected random access lead code.

12, method according to claim 11 wherein, equals the length of ZC root sequence with two root index sums of two the continuous corresponding ZC root of logic index sequences.

13, method according to claim 11, wherein, the identifier of access at random by physical downlink control channel (PDCCH) comes the accidental access response on the addressing downlink sharied signal channel (DL-SCH).

14, method according to claim 11, this method is further comprising the steps of:

To generate random access lead code, wherein, this cyclic shift parameter is used to obtain the value of cyclic shift from base station receive logic index and cyclic shift parameter.

15, a kind of method of in wireless communication system, carrying out random access procedure, this method may further comprise the steps:

Send predetermined cyclic shift parameter and the source logic index that is used to generate a plurality of random access lead codes;

The random access lead code that reception is selected from described a plurality of random access lead codes, described a plurality of random access lead codes are to generate according to the available cycles displacement of the ZC root sequence with described source logic index and at least one continuous logic index of described source logic index; And

Transmission comprises the accidental access response of the identifier of described random access lead code.

16, method according to claim 15 wherein, is broadcasted described source logic index as the part of system information.

17, method according to claim 15 wherein, equals the length of ZC root sequence with two root index sums of two the continuous corresponding ZC root of logic index sequences.

18, method according to claim 15, this method is further comprising the steps of:

Receive the cyclic shift parameter, wherein utilize described cyclic shift parameter to try to achieve the value of described cyclic shift.

19, a kind of method that generates random access lead code, this method may further comprise the steps:

According to a ZC root sequence, generate random access lead code according to the order that increases cyclic shift with first index that is mapped to the first logic index; And

In the time can not generating the random access lead code of predetermined quantity according to a described ZC root sequence, according to the 2nd ZC root sequence with second index that is mapped to the second logic index, generate other random access lead code according to the order that increases cyclic shift, described second logic index and the described first logic index are continuous.

20, method according to claim 19, this method is further comprising the steps of:

Receive the described first logic index from the base station.

21, method according to claim 19, wherein, the described predetermined quantity of random access lead code is 64.

22, method according to claim 19, this method is further comprising the steps of:

Receive the information of relevant cyclic shift parameter, wherein utilize this cyclic shift parameter to try to achieve the value of cyclic shift.

23, method according to claim 19, this method is further comprising the steps of:

From described random access lead code and described other random access lead code, select random access lead code; And

Send selected random access lead code.

24, a kind of method that generates random access lead code, this method may further comprise the steps:

Receive the information of relevant source logic index; And

According to ZC root sequence with the continuous logic index that originates in described source logic index, generate random access lead code according to the order that increases cyclic shift, until the random access lead code that has obtained predetermined quantity, wherein, described continuous logic index is mapped to the root index of ZC root sequence.

25, method according to claim 24 wherein, according to ZC root sequence, generates described random access lead code according to the order that increases cyclic shift.

26, method according to claim 25, this method is further comprising the steps of:

Receive the information of relevant cyclic shift parameter, wherein utilize this cyclic shift parameter to try to achieve the value of cyclic shift.

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