WO2008000189A1

WO2008000189A1 - A method and devices for sending the access preamble in the course of random access

Info

Publication number: WO2008000189A1
Application number: PCT/CN2007/070161
Authority: WO
Inventors: Wei Ruan; Yinggang Du
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2006-06-23
Filing date: 2007-06-22
Publication date: 2008-01-03
Also published as: CN101094511B; CN101094511A

Abstract

A method and devices for sending the access preamble in the course of random access are provided. The method includes: the types of access preamble with different length in time domain are set; the relation is set between the distance from a terminal to a base station, and/or random access channel quality, and/or terminal speed and the access preamble with different length in time domain; the terminal detects the above distance and/or quality and/or speed, then determines and sets the access preamble type according to the relation; finally, sends the preamble. Therefore, the terminal near the base station in the cell can avoid adopting a too long access preamble in time domain, which prevents the wasting of time and frequency resource and the delay of random access time.

Description

A method and apparatus for transmitting an access prefix in a random access procedure.

The present invention relates to an access technology for a terminal in a wireless communication system, and more particularly to a method and apparatus for transmitting an access prefix in a random access procedure. Background of the invention

Wireless communication systems all need to provide communication services for a certain number of terminals. These terminals are dispersed in the coverage of different base stations of the wireless communication system. When the terminal wants to communicate, it first needs to initiate a random access procedure to the associated base station. Therefore, random access Technology plays an important role in all types of wireless communication systems

In the random access process, the terminal first needs to send an access prefix to the associated base station through the random access channel, and is used to request uplink synchronization with the associated base station, and may include a signature indicating a random identifier (ID, MeMky) and other information. Sequence; Then, the terminal performs uplink synchronization with the owning base station according to the timing information sent by the base station, and then sends an access request message, which is used to request the establishment of the service channel link between the terminal and the associated base station.

The access prefix is also called an access probe.

The setting of the access prefix needs to consider the difficulty of the base station in capturing the access prefix. In addition to the signature sequence type included in the access prefix, the length of the time domain occupied by the access prefix also has a certain impact on the difficulty of the base station. In any unit time, the maximum transmit power used by the terminal to transmit the access prefix is limited. Only by accumulating in the time domain can the base station capture the detection energy of the access prefix. Therefore, the access prefix that occupies a longer time domain length can obtain a larger detection energy, which facilitates the base station to capture the access prefix. The access prefix that occupies a shorter time domain length obtains a smaller detection energy, and is randomly connected. In the case of inbound channel. Quality _ is poor, the base station is difficult to capture the access prefix. On the other hand, when the base station captures an access prefix that occupies more time domain lengths, it takes a long time, that is, only after receiving all time-frequency resources related to the access prefix, the base station can complete the acquisition. For example, in an Orthogonal Frequency Division Multiplexing (OFDM) system, an access prefix occupies three physical frames, and the base station only completes the access after receiving the three physical frames. Capture of the prefix. Accordingly, the base station requires less time when capturing an access prefix that occupies less time domain length. Therefore, for access prefixes occupying different time domain lengths, each has advantages and is suitable for different random access situations.

Figure 1 shows the structure of the access prefix of the prior art. Three access prefixes of different time domain lengths are set according to the size of the cell where the terminal is located.

When the cell where the terminal is currently located is small, for example, the radius of the cell is less than: 13 km, the access prefix of the first column is used, and the access prefix occupies one subframe; when the cell where the terminal is currently located is larger, such as the radius of the cell When the distance is greater than 13 km and less than 28 km, the access prefix of the second column is used, occupying two subframes, and the information contained in the access prefix, such as the signature sequence, is repeated once; when the current cell of the terminal is large, such as a cell When the radius is greater than 28 km, the access prefix of the third column is used, occupying three subframes, and the information of the access prefix is repeated twice. After the access prefix is sent on the following channel > The protection time is also set, and the protection time is also increased with the increase of the cell.

The advantage of setting the access prefix in this way is: For a small cell, there is a shorter random access period, and the access prefix occupies a shorter time domain length. Small cells are usually busy cells. These cells have more terminals, shorter random access periods, and shorter time domain lengths, which facilitates frequent random access of multiple terminals. Terminal random ~ efficiency. For a large cell, the terminal located at the edge of the cell is far away from the base station, and the access prefix sent by the terminal has a large path loss. The longer the time domain length of the access prefix can increase the detection energy, which is beneficial to offset the path loss. Impact, improve the ability of the base station to capture the access prefix. Large protection time also allows the base station to tolerate large synchronization errors during uplink synchronization search. Poor, facilitating random access synchronization of terminals at the cell edge.

However, there are also disadvantages in using this method: For a larger or larger cell, the access prefix occupies a longer time domain length, which is advantageous for random access of a terminal at a cell edge that is farther from the cell base station, but for the cell. A terminal that is closer to the base station of the cell is unnecessary. If an access prefix that occupies a longer time domain length is used, not only the time-frequency resources in the cell are wasted, but also the time of random access is extended, and the random access is reduced. s efficiency. Summary of the invention

The embodiment of the invention provides a method for transmitting an access prefix in a random access procedure, and the key method can avoid wasting time-frequency resources in a large cell and prolonging the time of random access.

The embodiment of the present invention further provides a transmitting device that sends an access prefix in a random access procedure, which can avoid wasting time-frequency resources in a large cell and prolonging the time of random access.

According to the above objective, the technical solution of the embodiment of the present invention is implemented by:

a method for transmitting an access prefix in a random access procedure, setting an access prefix type having different time domain lengths in a cell, and setting a terminal-to-base station distance value, or/and a random access channel quality value, or And the correspondence between the current moving speed of the terminal and the access prefix type of different time domain lengths, the method further includes:

The terminal detects the distance value of the current cell base station or the reverse access target cell base station, or / and the access channel quality value, or / and the current mobile terminal speed;

The terminal determines, according to the set correspondence relationship, the detected distance value, or/and the access channel quality value> or/and the access prefix type corresponding to the current mobile speed of the terminal, and sends the current access cell according to the time domain length setting of the type. After the base station or the reverse access target base station access prefix, send „

A transmitting device for transmitting an access prefix in a random access process, characterized in that The device includes n access prefix generators, a prefix type selector, a random access channel, an OFDM modulation module, and an antenna, where

0 access prefix generators are respectively used to generate the prefix/prefix with different time domain lengths and then sent to the prefix type selector;

a prefix type selector, configured to receive a time domain length according to a distance value of the terminal to the current cell base station or the reverse access target cell base station or/and a random access channel shield value or/and a current mobile terminal speed Ο After selecting a corresponding access prefix from different access prefixes, sending the access prefix to the random access channel;

a random access channel, configured to perform OFDM modulation on the received access prefix through an orthogonal frequency division multiplexing OFDM modulation module, and then send the antenna through the antenna

A transmitting apparatus for transmitting an access prefix in a random access process, the apparatus comprising a different length signature sequence selector, a DFT transform module, a subcarrier mapping module, and an OFDM modulation mode different length signature sequence escaper, configured according to the terminal Sending a signature sequence of a corresponding length to the current cell base station or the reverse access target cell base station or/and the random access channel quality value or/and the terminal current moving speed, and sending the signature sequence to the DFT transform module;

a DFT transform module, configured to perform DFT transform on the received signature sequence of the corresponding length, and send the signal to the subcarrier mapping module;

a subcarrier mapping module, configured to map the received DFT transformed signature sequence, and map the DFT transformed signature sequence to a subcarrier of the OFDM symbol, and send the signal to the OFDM tuner module;

OFDM: a modulation module, configured to perform OFDM modulation on the received DFT-transformed signature sequence on the sub-carrier of the OFDM: symbol, and transmit it as an access prefix through the antenna.

Between the OFDM modulation module and the antenna, a transmission slot selection module is further included for After the OFDM modulated signature sequence is selected by the transmission slot, it is sent as an access prefix through the antenna.

It can be seen from the above solution that the embodiment of the present invention sets multiple access prefixes of different time domain lengths for a cell, and the terminals in the cell are based on the distance from the neighboring base station or/and the quality of the current random channel or/and the terminal. The current mobile speed is initiated by using an access prefix that occupies different time domain lengths. Therefore, in the embodiment of the present invention, a terminal that is closer to the cell base station in a large cell or a terminal that is faster in moving speed does not use an access prefix that occupies a longer time domain length, thereby avoiding wasteful of a large cell. Time-frequency resources and delays. Long time; ^ access time. BRIEF DESCRIPTION OF THE DRAWINGS

1 is a schematic diagram of recording of a prior art access prefix;

2 is a flow chart of a method for sending an access prefix in an access procedure according to an embodiment of the present invention;

3 is a schematic structural diagram of an access prefix according to a first embodiment of the present invention; FIG. 4 is a schematic diagram of a transmitting apparatus for transmitting an access prefix in a random access procedure according to a specific embodiment of the present invention;

5 is a schematic diagram of an access prefix multiplexed in an FDM according to a fourth embodiment of the present invention;

6a and FIG. 6b are schematic diagrams showing the structure 2 of the access prefix multiplexing in the FDM according to the specific embodiment of the present invention;

FIG. 7 is a schematic diagram of a structure of an access prefix multiplexed in a 提供 according to a sixth embodiment of the present invention. FIG. 8 is a schematic diagram of different types of cells according to a seventh embodiment of the present invention; FIG. Schematic diagram of the access prefix structure; FIG. 10 is a schematic diagram of a transmitting apparatus for transmitting an access prefix in a random access procedure according to Embodiment 8 of the present invention. Mode for carrying out the invention

In order to make the objects, technical solutions and advantages of the present invention more comprehensible, the present invention will be further described in detail below with reference to the accompanying drawings.

In the embodiment of the present invention, the access prefix of the terminal from the neighboring base station or/and the current random channel quality or/and the current moving speed of the terminal adopts an access prefix occupying different time domain lengths, which ensures that the base station captures the The success rate of the access prefix sent by the terminal, which saves the time-frequency resource of the cell and shortens the random access time of the terminal, improves the random access efficiency of the terminal. In the embodiment of the present invention, when the terminal is close to the base station or/or When the quality of the current random channel is good, the terminal is allocated an access prefix that occupies a shorter time domain length. When the terminal is far away from the base station or/and the quality of the current random channel is bad, the terminal is allocated a long time domain length. The incoming prefix can make the access prefix sent by the terminal meet certain performance values when received by the affiliated base station, such as a certain average detected signal-to-noise ratio, which is given empirically when performing random access system setting.

In the embodiment of the present invention, for a terminal in a cell with a relatively small radius, an access prefix of the first column shown in the figure may be used. For a terminal in a cell having a relatively large radius, an access prefix occupying different time-frequency resources is used according to the distance of the terminal from the base station or/and the quality of the current random channel, that is, the first column shown in FIG. 1 may be used. The access prefix of the second or third column.

The embodiment of the present invention can also use the access prefix of different time domain lengths according to the current moving speed of the terminal, which can also ensure that the base station captures the access prefix success rate sent by the reading terminal and saves the time-frequency resources of the cell and shortens. The random access time of the terminal improves the random access efficiency of the terminal. FIG. 2 is a flowchart of a method for sending and sending an access prefix in a random access procedure according to an embodiment of the present invention, where specific steps are as follows:

Step 200: Set a correspondence between a terminal-to-base station distance value or/and a random access channel quality value, or / and a current mobile terminal speed and an access prefix type of different time domain lengths used.

The corresponding relationship may be set in the terminal, or may be set in the base station to which the terminal belongs, and the base station to which the terminal belongs broadcasts the corresponding relationship message to the terminal through the downlink broadcast channel.

Step 201: The terminal determines a current distance value to the base station or/and a random access channel quality value, or/and a current mobile terminal speed.

The terminal determines that the current distance value can be determined by a Global Positioning System (GPS) positioning or other existing positioning methods, and determining the current random access channel quality value may be performed by detecting a downlink pilot power or a signal to noise ratio in the cell. To determine, the current moving speed can be determined by detecting the speed of the downlink pilot quality, the GPS speed measurement method or other existing speed measurement methods.

The access channel quality value may be the intra-cell downlink pilot power value or the SNR value step 202, and the terminal determines the current distance value or/and the random access channel quality value, or/and the terminal current mobile according to the set correspondence relationship. After the access prefix type corresponding to the speed is set, the type is set to be sent to the currently located cell base station and then sent.

In step 201, the terminal may further determine whether the currently located cell is a cell with multiple access prefix types, and the basis for the determination is determined according to the information sent by the wide faint channel of the cell in the cell, and if yes, step 201 is performed. Otherwise, according to the process in the prior art, the access prefix specified by the cell is used to initiate the follow-up process. When the cell has multiple access prefix types, the base station that is responsible for the cell may send the bearer identifier through the downlink broadcast channel. The cell has multiple access prefix type information.

In the embodiment of the present invention, if the terminal switches or other related situations, the terminal Not only the distance value to the base station of the current cell or/and the random access channel quality value, or/and the current mobile terminal speed, but also the distance value to the reverse access target cell base station or/and the random access channel can be determined. Method for determining the quality value, or/and the current moving speed of the terminal, thereby selecting the corresponding access prefix to be sent to the reverse access target cell, the reverse access target cell base station, and selecting the corresponding access prefix to be sent to the reverse access target cell as shown in picture 2

In the embodiment of the present invention, the access prefix occupying different time domain lengths may be code division multiplexing (CDM), frequency division multiplexing (FDM, Frequency).

Division Multiplexing), or multiplexed by Time Division Multiplexing (TDM), and then transmitted to the base station. For example, in the CDM mode, the signature sequences in the access prefix may be grouped, and the time domain lengths of the prefixes corresponding to the signature sequences of different groups are different. The terminal according to the previous distance value or/and the random incoming channel quality value or/and the terminal. The current mobile speed is selected in the different groups of the signature sequence to be sent in the access prefix, and the base station to which the terminal belongs uses the time domain window of different lengths to capture the access prefix. The FI3M mode, that is, the access prefix of different time domain lengths does not occupy 13⁄4. The frequency band is transmitted in the random access channel, and the terminal selects the corresponding frequency band to send an access prefix according to the current distance value or/and the random access channel quality value or/and the current moving speed of the terminal, and the base station to which the terminal belongs uses different frequency bands. The domain window captures the access prefix. The TDM mode, that is, the access prefixes of different time domain lengths occupy different time slots of the same frequency band and are sent in the random access channel, and the terminal 4 according to the current distance value or/and the random access channel quality value. Or/and the corresponding time slot on the current mobile speed selection band of the terminal sends an access prefix, and the terminal belongs to the station Different time slots of time domain window capture Di access preamble.

The following describes an embodiment of the present invention by way of specific embodiments.

Specific embodiment 1

It is assumed that the wireless communication system is an Orthogooa! Frequency Division Multiplexing Access (OFDMA) system, which supports three different time domain length access prefixes, as shown in FIG. The access prefix is the shortest access prefix. It consists of a signature sequence, which is smaller than one physical frame, plus the guard time is one physical frame. The access prefix 2 is the second long access prefix, consisting of two repeated signature sequences, plus two protections. The time constitutes two physical frames; the prefix: 5 is the longest access prefix, consisting of three repeated signature sequences, plus three guard times to form three physical frames.

In the system, two thresholds A1 and A2 are set. When the terminal detects that the downlink pilot signal to noise ratio is greater than or equal to A1, the terminal adopts the access prefix 1; when the terminal detects that the downlink pilot signal to noise ratio is less than A1 is greater than or equal to A2. When the terminal detects that the downlink pilot signal-to-noise ratio is less than A2, the terminal adopts the access prefix 3»A1 and M is empirically obtained when the system is set.

In this system, the terminals of the system can be divided into three categories, and different access prefixes are used to perform random access procedures.

FIG. 3 is a schematic diagram of a transmitting apparatus for transmitting an access prefix in a random access procedure according to a specific embodiment of the present invention, where the transmitting apparatus is generally used in a system employing OFDMA, wherein the transmitting apparatus includes 31 access prefix generators. The access prefixes with different time domain lengths are respectively generated and sent to the prefix type selector. The prefix type selector selects one of the access prefixes according to the current random access channel quality value, and then sends the signal to the random access channel. The module performs OFDM modulation and transmits it through the antenna.

The receiving device that receives the access prefix in the random access process in the embodiment of the present invention is the same as the prior art, except that when the access prefix is captured, the access prefix with different time domain lengths is separately captured.

Concrete example two

Assuming that the wireless communication system is an OFDM system, the system supports three different time domain length access prefixes: The access prefix is the shortest access prefix, consisting of a signature sequence, the signature sequence is less than one physical frame, plus protection time Is a physical frame; access prefix 2 is the second long access prefix, consisting of two repeated signature sequences, plus two guard times to form two physical dens; access prefix 3 is the longest access Prefix, consisting of three repeated signature sequences The composition, plus three guard times, constitutes three physical frames.

Set two thresholds B1 and B2 in the system. When the terminal detects that the current moving speed is not less than 'B1>, the incoming prefix uses the access prefix. When the terminal detects that the current moving speed is less than B1 is greater than B2, access The prefix uses the access prefix 2; when the terminal detects that the current moving speed is not greater than B2, the access prefix uses the access prefix 3. Thresholds B1 and B2 are given by experience when set.

In this way, the terminals of the Weng system are classified into three types, which use different types of access prefixes. The current high speed uses a short access prefix, and the current low speed uses a long access prefix. This system can also use the transmitting device shown in Figure 4, except that the prefix type selector ^ "terminal current moving speed selects one of the access prefixes and sends it to the following channel.

Specific examples

Assume that the wireless communication system is an OFI3M system, which supports two different time domain length access prefixes: Access prefix 1. Short access prefix, consisting of one signature sequence, occupying N consecutive OFDM symbols; Prefix 2 is a long access prefix consisting of two repeated signature sequences, occupying 2N consecutive OFDM symbols.

The threshold A of the pilot strength and the threshold B of the terminal moving speed are set in the system. When the terminal detects that the current moving speed is not less than B, the access prefix 1 is used; when the terminal detects that the current moving speed is less than B and the pilot strength When the terminal is less than A, the access prefix 2 is used. When the terminal detects that the current moving speed is less than B and the pilot strength is not less than A, the access prefix 1 threshold A and the threshold B are set by experience.

In this way, the terminals of the system are classified into two types, each adopting different types of access prefixes, and the current high speed adopts a short-length access prefix, and the current speed is low and the pilot strength is small. It is also possible to use the transmitting device shown in FIG. 4, except that the prefix type selector is selected according to the current moving speed of the terminal and the random access channel quality value. After an access prefix occurs by two prefix sequence generators, it is sent to the random access channel.

The access prefixes of different time domain lengths can be multiplexed in the CDM mode. That is, the access prefix of the time domain length occupies the same time-frequency resource, and the sequence of the hypothetical access prefix is differentiated by different sequence codes. a signature sequence, which is divided into three groups, wherein the first group is used in the structure of the access prefix 1 shown in FIG. 3, and the second group is used in the structure of the access prefix 2 shown in FIG. The group is used in the structure of the access prefix 3 shown in S3.

As shown in FIG. 5, access prefixes of different structures overlap in the time-frequency domain, and _β is distinguished by different signature sequences. Generally, the cross-correlation between different signature sequences is small, for example, using a Walsh sequence, GCL. Sequences and PN sequences are used as signature sequences, so the interference between different access prefixes is small and does not affect the acquisition of base station access prefixes.

Specific examples 5

The access prefixes of different time-domain lengths can be used in the FDM mode. That is, the access prefixes of different time domain lengths occupy different frequency bands. After the terminal determines the used access prefix, it sends and receives the corresponding frequency band. In the prefix, the base station uses different length time domain windows on different frequency bands to detect the access prefix.

As shown in Fig. 6a and Fig. 6b, different access prefixes do not overlap in the frequency domain, and they use different frequency bands, so there is no interference between them. It is composed of access prefixes on the three frequency bands in the random access channel, and relatively more time-frequency resources are occupied by the CDM mode. In Figure 6, the access prefix has 3 access slots in 3 frames, which is more than the access slots of other access prefixes. The advantage of this setting is that in a large cell, usually close to the base station. More terminals, more time slots can meet the simultaneous access of more terminals

Concrete embodiment 6

The access prefixes of different time domain lengths can be used in the TDM mode. That is, the access prefixes of different time domain lengths occupy the same frequency band, but occupy different time slots. When the terminal is After the access prefix is used, the used access prefix is transmitted on the corresponding time slot, and the base station uses the time domain window to capture the access prefix on different time slots.

As shown in Figure 7, the access prefixes of different time domain lengths do not overlap in the time-frequency domain. > They are multiplexed on different time slots, so there is no interference between them. The random access channel is formed by a time-frequency block group in this frequency band, and relatively more time-frequency resources are occupied by the CDM.

Specific; 3⁄4 case seven

In cellular mobile communication systems, the size of the cell radius does not vary greatly. For example, the radius of a suburb and a remote area is much larger than the radius of a city in a bustling area.

According to the size of the cell radius, the cell is divided into three small (Sma l ), medium (Medium), and large (Large) three small cells for the small cell, the radius of the cell is small, and one type of terminal is included, that is, the shortest connection is used. The prefixed terminal for the cell of Ivfedium contains two types of terminals, namely the terminal using the shortest access prefix and the terminal using the second short access prefix. For a large cell, its cell contains three types of terminals, that is, a terminal using the shortest access prefix, a terminal using the second short access prefix, and a terminal using the longest access prefix.

The identification of the different types of cells by the terminal is obtained by receiving the information of the downlink broadcast channel after entering the cell, and after the base station is established, according to the coverage of the base station, the covered cells are set to the corresponding type, and This information is notified to the terminal of the cell through the downlink broadcast channel.

As shown in Figure 8: The cell of Sma] has a smaller radius, and one type of access prefix can meet the requirements. The Medium cell requires two types of access prefixes, and the Large cell requires three types of access. In the prefix, the area drawn by the slash is the access prefix: the area covered by 1 , the area drawn by the m character is the area covered by the access prefix 2; the area drawn by the vertical line is covered by the access prefix 3. Area

Specific facts. Access prefixes of different time domain lengths can also be implemented in one physical frame. For example,

The number of subcarriers included in the OFDM system is 512, and one physical frame contains 8 OFDM symbols. The number of subcarriers allocated to the random access channel is consecutive 128 subcarriers. As shown in Figure 9, the four access prefixes are classified into two types, one for four consecutive OFDM symbols, and the other for eight consecutive OFDM symbols. For example, the Walsh code is used as the access prefix. The first type is used. The Walsh code is 512 in length, and the second is Walsh code in length 1024. The first type of access prefix is arranged in an array of .128 rows and 4 columns. Each column is subjected to a 128-point discrete Fourier transform (DFT _? Discrete Fourier Trajisform), and then mapped to 28 subcarriers of the OFDM symbol, after OFDM modulation. Send out through the antenna. The four columns are transmitted through four consecutive OFDM symbols, and the first four OFDM symbols or the last four OFDM symbols of one frame can be randomly selected. The two access prefixes are arranged in an array of 28 rows and eight columns, and each column passes through 128. After the DFT transform of the point, it is quickly transmitted to the 128 subcarriers of the OFDM symbol, and after OFDM modulation, the two access prefixes are sent out through the antenna through code division multiplexing. For example, an Hsh code with an even-numbered index in the Walsh code of length 5]2 is assigned as an access prefix to the first random access prefix, that is, "256", face, ^, etc. 256 will be 1024 in length. The Walsh code with the odd-numbered index in the W lsh code is allocated as the access prefix. For the second random access prefix, ie ^, medical ⁴ , ^ ^5, etc. ₅ 】 2. Two access prefix multiplexes are randomly connected On the channel, they are orthogonal to each other in the code domain, and no mutual interference is formed.

Or the Walsh code division method may also be as follows: The first Ns of the Walsh code of length 5]2 is used as a signature sequence to assign an access prefix, that is, draw ^: , , , ^Wai -; The Walsh code of length 5 〗 2 is extended to a subcode of length 1024, that is, ( ^ί , Waish^, ), (discussion, Wa^^ ), (

^ ^sh ^2 ), ( W^^ , Wai^ ₎ ; is assigned to the second access prefix, In this way, the ratio of the number of signatures of the two access prefixes can be arbitrarily selected, and Ns is an integer.

The transmitting device that implements the above-mentioned access prefix transmission is shown in FIG. 10: the terminal according to the distance to the current cell base station or the reverse access target cell base station, or/and the random access channel quality value, or/and the terminal current mobile Speed, select a signature sequence of a suitable length in a signature sequence selector of different lengths, and the signature sequence is subjected to DFT transformation by a DFT transform module, and the DFT-transformed signature sequence is mapped to the OFDM symbol by subcarrier mapping of the subcarrier mapping module. On the subcarrier, after OFDM modulation by the OFDM modulation module, the transmission time slot is selected: the module selects the appropriate time slot to send out _β. For the 512-order Walsh code, the first 4 OFDM symbols of one physical frame or The last 4 OFDM symbols; for the 1024-order Walsh code is transmitted at the beginning of a physical frame.

The present invention provides several access prefixes with different time domain lengths in the same cell to meet the needs of terminals within the cell that are different from each other or/and different channel quality or/and current mobile speed: Or / and the channel with poor channel quality or / and the current moving speed adopts an access prefix with a long time domain length to improve the signal to noise ratio of the access prefix, increase the probability of the base station accessing the access prefix, and the terminal close to the base station or / and the channel quality is good or / and the current mobile speed is slow. The access prefix with a short time domain length is used to reduce the time-frequency resource of the cell occupied by a single access prefix, improve the utilization of the time-frequency resource of the cell, and improve the random access. The speed of the process „ In the embodiment of the present invention, several multiplexing methods of access prefixes with different time domain lengths are also proposed, which can be flexibly set according to the needs of the current system.

In the embodiment of the present invention, the cells with different radii are distinguished, and the small cell adopts a time domain with a large access prefix and a plurality of time domain length access prefixes, thereby improving the random access system. Overall performance.

The specific embodiments described above further explain the technical solutions and the beneficial effects of the present invention. It should be understood that the above description is only the specific implementation of the present invention. The invention is not intended to limit the invention, and any modifications, equivalents, improvements, etc., which are within the spirit and scope of the invention, are intended to be included within the scope of the invention.

Claims

Request

A method for transmitting an access prefix in a random access procedure, characterized in that: setting an access prefix type with different time domain lengths in a small > setting a terminal-to-base station distance value, or/and random access Correspondence between the channel quality value, or / and the current mobile speed of the terminal and the access prefix type of different time domain lengths > The method further includes:

The terminal detects the distance value of the current cell base station or the reverse access target cell base station, or / and the random access channel quality value, or / and the current mobile terminal speed;

The terminal determines, according to the set correspondence relationship, the detected distance value> or Z and the random access channel quality value, or/and the access prefix type corresponding to the current moving speed of the terminal, and sends the current access group according to the time domain length setting of the type. Sending after the access prefix of the cell base station or the reverse access ^ 3 standard cell base station

2. The method of claim 2, wherein in the Orthogonal Frequency Division Multiplexing (OFDM) OFDM system, the access prefix is sent as:

Pre-access 鳆 carries and transmits on consecutive OFDM symbols

3. The method according to claim 2, wherein: the access prefix is sent on the continuous OFDM symbol as:

The signature sequence of the access prefix is divided into a number of sub-sequences of the consecutive OFDM symbols, and each sub-sequence is subjected to discrete Fourier DFT transform, mapped onto consecutive sub-carriers of the OFDM symbol, and after OFDM modulation, transmitted through the antenna.

4. A method as claimed in claim 3, characterized in that the signature sequence is a Wa!sJi code sequence, a GCL sequence or a DFT sequence.

5. The method according to claim 4, wherein when the signature sequence is a Wakh code, and the access prefix is divided into two types, the selection process of the signature sequence is:

The first Ns Walsh code sequences in the Walsh code of order N 1 are taken as the signature sequence of the short access prefix; the remaining Ni -Ns are on the child nodes of the N1 order Wajsh code tree The order of the Walsh code sequence is the signature sequence of the long access prefix. The N is 5.12 and the N2 is !024. The Ns is an integer.

6. The method according to claim 4, wherein when the order NI of the Walsh code is 5.12 and the N2 is 1024, and the access prefix is divided into two types, the selection process of the signature sequence is :

The Wa sJi code of the short access prefix is:

The %3⁄4lsh code of the long access prefix is: ( Walsh-,

(Sa, painting), (painting, yang ^ hidden) _t<

The method of claim 4, wherein when the order of the Walsh code is N1, the N2 is 1024, and the access prefix is divided into two types, the selection process of the signature sequence is:

The Walsh code of the short access prefix is: ² , ² , ,,

Walsh, where the long access prefix Walsh code is: ^li!S4 WaLs i

And

Wah ^ Yang

8. The method of claim 2, wherein in an OFDM system each of which includes 8 OFDM: symbols, and when the access prefix is divided into two types, the access prefix is on consecutive OFDM symbols The bearer is sent as:

The short access prefix modulation carries the transmission on 4 consecutive OFDM symbols, wherein the long access prefix modulation carries the transmission on 8 consecutive OFDM symbols.

9. The method of claim 8, wherein said short access is The prefix modulation carries the transmission on 4 consecutive OFDM symbols, where the long access prefix modulation is carried on 8 consecutive OFDM symbols and is transmitted as:

Divide the Waisli code with a short access prefix into 128 rows and 4 columns, each column going through! After the 28-point DFT transform, it is mapped to 128 consecutive subcarriers of the OFDM symbol, and after OFDM modulation, it is transmitted through the antenna; the Wa code of the long access prefix is divided into 28 rows and 8 columns, each column respectively After 128 points of DFT transform, it is mapped to 128 consecutive subcarriers of OFDM symbols, and after OFDM modulation, it is transmitted through the antenna.

The method according to claim 8, wherein the sending of the short access preamble is performed by randomly selecting the first 4 OFDM symbols or the last 4 OFDM symbols of one physical frame.

1. The method of claim 1, wherein the terminal detects a distance value of a current cell base station or a reverse access target cell base station, or/and a random access channel quality value, or / and before the terminal's current moving speed, the reading method also includes:

The terminal determines whether the current cell or the reverse access target cell is set to have different time domains according to whether the current cell site or the reverse access target cell base station sends the access prefix type information with different time domain lengths sent by the downlink broadcast channel. The access prefix type of the length, if yes, performing the terminal detecting step; otherwise, setting the access prefix by using the access prefix type set by the current cell or the reverse access target cell, and then sending the packet to the current cell site or Access to the a-cell base station

The method according to claim U, wherein the information about the access prefix type of the time domain length that is sent by the current cell base station or the reverse access target cell base station of the terminal through the downlink broadcast channel is :

The base station or the reverse access target cell base station of the terminal currently determines whether to set the access prefix type of different time domain lengths in the cell according to the radius of the covered cell, and if yes, the downlink broadcast channel is configured to be sent. Different time domain lengths before access Type information; otherwise, the access prefix type information without setting different time domain lengths or not sending information is sent through the downlink broadcast channel.

13. The method according to claim ,, wherein the random access channel quality value is a downlink pilot power value or a signal to noise ratio value in a current cell of the terminal.

14. The method according to claim 12, wherein the terminal detects that the distance value of the current base station or the reverse access target cell base station is detected by the global positioning system GPS positioning mode;

The random access channel quality value is determined by detecting a downlink pilot power or a signal to noise ratio in a current cell or a reverse access Q target cell of the terminal;

The current moving speed of the terminal is determined by detecting the change speed of the downlink pilot quality, or GPS.

The method according to claim 1, wherein the transmitting the pre-access level to the current cell base station or the reverse access target cell base station is multiplexed and transmitted by a code division multiplexing CDM method, and the process is For:

Determining, in advance, the signature sequences having different time domain lengths included in the access prefix, and selecting, by the terminal, the signature sequence in one of the groups according to the time domain length of the determined access prefix type to be included in the access prefix and sending;

The method further includes: capturing, by the terminal base station or the reverse access target cell base station, the access prefix by using a time domain window of different lengths.

The method according to claim 1, wherein the sending the access prefix to the current cell base station or the reverse access target cell base station is multiplexed and transmitted by frequency division multiplexing (FDM), and the process is:

The terminal sends the access prefix occupying different frequency bands according to the time domain length of the determined access prefix type, and then sends the terminal;

The method further includes: the cell base station or the reverse access target cell base station currently connected by the terminal Time domain window over different frequency bands captures the access prefix

17. The method as claimed in claim 1, wherein the sending the access prefix to the current cell base station or the reverse access target cell base station is performed by time division multiplexing TDM mode multiplexing, and the process is:

The terminal sends an access prefix that occupies different slots of the same frequency band according to the time domain length of the determined access prefix type, and then sends the access prefix;

The method further includes: the cell base station or the reverse access target cell base station to which the terminal currently belongs captures the access prefix by using a time domain window in different time slots.

18. A transmitting apparatus for transmitting an access prefix in a random access procedure, characterized in that: the apparatus comprises n access prefix generators, a prefix type selector, a random access channel, an OFDM modulation module, and an antenna, wherein ,

0 access prefix generators are respectively configured to generate access prefixes with different time domain lengths and then send them to the prefix type selector;

The random access channel is configured to perform OFDM modulation on the received access prefix by using an orthogonal frequency division multiplexing OFDM modulation module, and then send the signal through the antenna.

A transmitting apparatus for transmitting an access prefix in a random access process, the apparatus comprising: a different length signature sequence selector, a DFT transform module, a subcarrier mapping module, an OFDM modulation module, and an antenna, where

Different length signature sequence selectors for selecting a corresponding length according to a distance value of the terminal to the current cell base station or the reverse access target cell base station or/and a random access channel quality value or/and a current mobile terminal speed The signature sequence is sent to the DFT transformation module; a DFT transform module, configured to perform DFT transform on a received signature sequence of a corresponding length,

a subcarrier mapping module, configured to map the received DFT transformed signature sequence, and map the I3FT transformed signature sequence to a subcarrier of the OFDM symbol, and send the signal to the OFDM modulation module;

An OFDM modulation module, configured to perform OFDM modulation on the received DFT-converted signature sequence on the subcarriers of the OFDM symbol, and send the same as an access prefix through the antenna.

20. The apparatus according to claim 9, further comprising: a transmission slot selection module between the OFDM modulation module and the antenna, configured to: after the OFDM-modulated signature sequence is selected by the transmission slot, The access prefix is sent through the antenna