CN101369840B - TDD accidental access method, system and its composition modules - Google Patents

Abstract

The present invention relates to a random access channel allocation method for a medium-coverage and large-coverage system in the TD-SCDMA evolution system based on OFDM modulation. By adding a guard interval to the random access preamble sequence, it can be used in the case of large interference. It can be allocated at the back end of the uplink time slot as much as possible, so as to solve the technical problem that the TS0 time slot and DwPTS time slot of the remote cell interfere with the random access preamble sequence of the local cell in medium coverage and large coverage systems. By adopting the invention, the distribution of the random access channel is more flexible, and the detection success probability of the preamble sequence by the base station is improved.

Description

Time division duplex random access method, system and components thereof

technical field

The present invention relates to the random access technology in the evolution system of Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) based on Orthogonal Frequency Division Multiplexing (Orthogonal Frequency Division Multiplexing, OFDM), in particular A time-division duplex random access method for medium coverage and large coverage systems, the system and its constituent modules.

Background technique

TD-SCDMA is the only international standard among the three major international standards of the third-generation mobile communication system that adopts time division duplex (TDD) mode and supports uplink and downlink asymmetric service transmission, and has greater flexibility in spectrum utilization. The system comprehensively adopts advanced technologies in wireless communication such as smart antenna, uplink synchronization, joint detection and software radio, so that the system has high performance and spectrum utilization. With the development of society and the advancement of technology, people's requirements for mobile communications are constantly increasing, and it is hoped that the system can provide data transmission services with large capacity, high speed, and low delay. In order to meet this growing demand, the TD-SCDMA system also needs to evolve and improve performance.

In the evolution scheme of TD-SCDMA, in order to obtain high-speed and large-capacity services, a wider bandwidth needs to be occupied, so it is called a broadband time-division duplex cellular system. In the broadband TDD cellular system, it is usually divided into three levels according to the radius of the cell to be covered. The coverage range of 0km to 10Km is usually called small coverage, 10km to 70km is medium coverage, and more than 70km is large coverage. .

The asynchronous random access preamble (preamble) sequence of the broadband TDD cellular system is used for uplink clock synchronization and UE identifier detection. In the broadband TDD cellular system with medium coverage and large coverage design, the preamble sequence is next to The uplink and downlink switching point, and the uplink and downlink switching time at this time just corresponds to the uplink and downlink protection of the cell radius, so the signal of the base station of the adjacent cell may interfere with the random access preamble sequence of the cell. In fact, the data time slot after the uplink and downlink guard intervals of the cell will also be interfered. However, for the data channel, the interference can be avoided through scheduling, and other interference avoidance or elimination methods can be adopted. Even if the data block is demodulated incorrectly, it can be retransmitted to ensure correct reception. However, for the random access channel, large interference has a great impact on the user terminal (UE), which will reduce the access success rate of the UE, prolong the random access time of the UE, and have a great impact on the specific use of the user. very big.

Figure 1(a) is the frame structure of the original TD-SCDMA evolution system in the broadband time division duplex cellular system, and Figure 1(b) is the frame structure in the case of large coverage in the broadband time division duplex cellular system, in which TS0 is fixed as downlink DwPTS is the downlink pilot time slot, GP is the uplink and downlink guard interval, and UpPTS is the uplink pilot time slot. In the figure, the ones marked with ↑ are uplink time slots, the ones marked with ↓ are downlink time slots, the dotted line between TS4 and TS6 or TSx means omission, and the middle time slots are not drawn. In a large coverage system, TSx represents the xth time slot. Since it is uncertain whether it is an uplink or downlink time slot, its uplink and downlink attributes are not marked in the figure. Since in the large coverage system, the random access channel occupies resources in the frequency domain, which cannot be represented by UpPTS time slots like the small coverage system, so in the large coverage system in Figure 1(b), the preamble sequence to identify.

In Figure 1(b), the random access preamble sequence is allocated next to the GP, where the length of the GP corresponds to twice the cell radius, that is, the time elapsed for twice the cell radius distance from the speed of light. In the case of medium coverage and large coverage, in order to meet the requirements of the signal-to-noise ratio received by the base station, the preamble sequence needs to be extended accordingly in the case of relatively small coverage. In the case of medium coverage and large coverage, when the UE in the local cell sends random access preamble sequences to the base station of the local cell, these random access preamble sequences will arrive at the local cell together with the TS0 time slot or DwPTS time slot signal of the remote cell The base station, that is to say, the random access preamble sequence of the local cell is interfered by the signal of the TS0 time slot and the DwPTS time slot of the remote cell, for example, the first-layer cell outside the local cell. In fact, the uplink data time slots of the UE in this cell, such as TS2 and TS3, are also interfered by the TS0 time slot and DwPTS time slot of the remote cell. Scheduling between time slots, or using interference coordination, or using interference avoidance methods to reduce the impact of remote cells on the uplink data time slots of this cell. Even if a detection error occurs in the data block in the case of interference, correct transmission can be ensured through retransmission. However, the signal interference of the TS0 time slot and the DwPTS time slot of the remote cell has a great impact on the preamble sequence. These interferences will reduce the reception quality of the preamble sequence by the base station of the cell, and reduce the success rate of random access detection. After the UE sends the preamble sequence for random access, it receives and detects the corresponding channel within the time it waits for the feedback from the base station to see if there is an access success indication fed back from the base station. Due to the existence of interference, the performance of the base station to detect the preamble sequence is degraded, resulting in the inability to correctly detect the preamble sequence. When the base station cannot correctly detect the preamble sequence, the base station does not send feedback information to the UE. If the UE does not detect a feedback signal on the corresponding feedback channel, it will wait until the preset waiting time expires, and then the UE will re-initiate another random access. Due to the last random access detection, many UEs did not receive correct feedback information. In the next moment, more UEs will send preamble sequences to the base station of the cell, which will cause the base station to detect multiple preamble sequences. Performance drops further.

To sum up, the interference of the TS0 time slot and the DwPTS time slot of the remote cell has a great impact on the random access process, and further affects the normal operation of the entire communication system.

Contents of the invention

In view of this, one of the objects of the present invention is to provide a method for allocating random access channels, which can solve the technical problem of the interference of the TS0 time slot and the DwPTS time slot of the remote cell to the random access preamble.

In order to achieve the above object, technical solution of the present invention is achieved in that way:

In order to achieve the above object, technical solution of the present invention is achieved in that way:

A time-division duplex random access method. When a mobile user terminal performs random access, it sends a preamble sequence to a cell base station through a random access channel, and a blank area is included in the random access channel as the Guard interval for the preamble sequence.

Based on the above technical solution, the guard interval is located after the preamble sequence and immediately adjacent to the preamble sequence.

Based on the above technical solution, the value range of the guard interval time length is greater than zero and less than or equal to the time elapsed by the speed of light corresponding to the distance of twice the cell radius.

Based on the above technical solution, the preamble sequence and the guard interval are allocated in the uplink time slots away from the uplink and downlink guard intervals.

Based on the above technical solution, the random access preamble sequence and its guard interval may span more than two time slots, and its total duration is obtained according to the following method:

Length (preamble sequence + guard interval) = N × Length (TS)

Wherein, Length represents a function for calculating the time length, N is a positive integer greater than or equal to 1 and less than or equal to the sum of all uplink time slots, and TS represents a single time slot.

Based on the above technical solution, the random access preamble sequence is a directly generated long synchronization code sequence, or is formed by repeating a short synchronization code sequence.

Based on the above technical solution, the synchronization code sequence is a Zadoff-Chu sequence, a GCL sequence, a Golay sequence or a Barker sequence.

Based on the above technical solution, a 521-point Zadoff-Chu sequence is used as a reference synchronization code sequence, and in the case of larger coverage, the 521-point Zadoff-Chu sequence is repeated to form a long preamble sequence.

Based on the above technical solution, the number of the 521-point Zadoff-Chu sequences constituting the preamble sequence is an integer value obtained by dividing the cell radius by 21.25 kilometers and rounding up.

Another object of the present invention is to provide a random access module for time division duplex terminals, which at least includes:

A sequence selection module, configured to select and obtain the preamble sequence in the broadcast information of the base station;

A random access channel forming module, configured to form a random access channel according to the broadcast information and the selected preamble sequence;

A sending module, configured to send a preamble sequence to a cell base station through a random access channel;

The base station response detection module is used to detect the base station response channel to determine whether the access is successful;

The random access channel includes a blank region as a guard interval of the preamble sequence.

Based on the above technical solution, the preamble sequence and the guard interval are located in the uplink time slot far away from the uplink and downlink guard intervals.

Based on the above technical solution, the random access preamble sequence and its guard interval may span more than two time slots, and its total duration is obtained according to the following method:

Length (preamble sequence + guard interval) = N × Length (TS)

Wherein, Length represents a function for calculating the time length, N is a positive integer greater than or equal to 1 and less than or equal to the sum of all uplink time slots, and TS represents a single time slot.

Another object of the present invention is to provide a random access module of a time division duplex base station, comprising at least:

The broadcast module is used to broadcast the location information of the random access channel and the preamble sequence usable by the cell through the broadcast channel;

A random access sequence detection module, configured to detect a preamble sequence in a random access channel;

A random access response module, configured to respond to the detected preamble sequence through a response channel;

It is characterized in that the random access channel includes a blank area as a guard interval of the preamble sequence.

Based on the above technical solution, the random access module of the base station further includes an uplink time slot setting module, configured to configure the uplink time slot according to the coverage and the time slot width occupied by the preamble sequence and guard interval.

Based on the above technical solution, a preamble sequence grouping module is also included, which is used for grouping according to the grouping conditions corresponding to each preamble sequence.

Another object of the present invention is to provide a time division duplex random access system, including a terminal random access module and a base station random access module, the terminal random access module at least includes:

A sequence selection module, configured to select and obtain the preamble sequence in the broadcast information of the base station;

A random access channel forming module, configured to form a random access channel according to the broadcast information and the selected preamble sequence;

A sending module, configured to send a preamble sequence to a cell base station through a random access channel;

The base station response detection module is used to detect the base station response channel to determine whether the access is successful;

The base station random access module includes at least:

The broadcast module is used to broadcast the location information of the random access channel and the preamble sequence usable by the cell through the broadcast channel;

A random access sequence detection module, configured to detect a preamble sequence in a random access channel;

A random access response module, configured to respond to the detected preamble sequence through a response channel;

The random access channel includes a blank region as a guard interval of the preamble sequence.

Based on the above technical solution, the preamble sequence and the guard interval are located in the uplink time slot far away from the uplink and downlink guard intervals.

Aiming at the wideband time division duplex cellular system, the present invention proposes a random access channel design scheme with a guard interval in medium coverage and large coverage, and does not require the preamble sequence to be adjacent to the uplink and downlink guard intervals, so that the random access channel The allocation is more flexible; in the present invention, the preamble sequence with the guard interval is placed in the uplink time slot position away from the uplink and downlink guard intervals, and according to the allocation criterion of the random access channel, the interference of the remote base station can be avoided as much as possible, ensuring The base station of this cell correctly detects the random access channel, so as to realize the accurate and fast random access of the terminal, and provides an effective solution for the OFDM system to realize the random access of the terminal.

Description of drawings

Fig. 1 (a) is the frame structure of the original TD-SCDMA evolution system and the design diagram of random access UpPTS;

Figure 1(b) is the frame structure of the TD-SCDMA evolved system in the case of large coverage;

Fig. 2 is the Preamble sequence structure following the guard interval proposed by the present invention;

Figure 3(a) is a random access channel position allocation map under the 5km coverage situation;

Figure 3(b) is a random access channel position allocation diagram under the 30km coverage;

Figure 3(c) is a random access channel position allocation diagram under the coverage of 100km;

Figure 4(a) is a random access channel position allocation diagram in the case that TS4 is a downlink time slot with 5km coverage;

Figure 4(b) is a random access channel position allocation diagram in the case that TS4 is a downlink time slot with 30km coverage;

Figure 4(c) is a random access channel location allocation diagram in the case that TS4 is a downlink time slot with 100km coverage;

Figure 5(a) is a random access channel structure diagram in the case of 20km coverage, using a 521-point Zadoff-Chu sequence;

Figure 5(b) is a random access channel structure diagram when two 521-point Zadoff-Chu sequences are used in the case of 40km coverage;

Figure 5(c) is a random access channel structure diagram in the case of using three 521-point Zadoff-Chu sequences in the case of 60km coverage;

FIG. 6 is a sequence diagram of a random access process between a UE and a base station;

FIG. 7 is a module composition diagram of the random access part of the terminal and the base station.

Detailed ways

The core idea of the present invention is to redesign the structure of the random access channel so that the redesigned random access channel can be flexibly configured in the uplink channel under the condition that the uplink channel allocation can be performed, and the random access channel of this cell The sending position of the preamble sequence is far away from the time when the TS0 time slot and DwPTS time slot of the remote base station arrive at the local cell, so as to reduce the interference of the TS0 time slot and DwPTS time slot of the remote base station on the preamble sequence of the local cell as much as possible, thereby improving random access Channel detection success rate and UE access speed.

The present invention includes a blank area that does not send any data in the random access channel, and the blank area is used as the guard interval (GT) of the preamble sequence to eliminate the time uncertainty of the preamble sequence. Data time slot interference, as shown in Figure 2. Using the improved random access channel allocation structure, the random access channel does not have to be limited to be allocated close to the GP, because the preamble sequence in this random access channel allocation structure has its own guard interval, which can prevent the preamble sequence from moving forward Or when moving backwards, the data time slots before and after are disturbed. The value range of GT is theoretically greater than zero and less than or equal to the time required for the speed of light to travel twice the distance of the cell radius. The value of GT is configurable, and its value is mainly determined by the height of the base station antenna when the base station receiving signal-to-noise ratio is satisfied. Generally, when the UE sends the preamble sequence, it estimates a timing advance so that the preamble sequence it sends can reach the base station at its target time. Taking Figure 3(b) as an example, the target time of the preamble sequence should be at the beginning of the TS3 time slot. If a UE is at the edge of the cell, the UE needs to advance the time of GT/2 when sending the preamble sequence, and it sends the preamble sequence It will arrive at the base station of the cell at the starting position of the TS3 time slot, so that the preamble sequence will not affect the preceding and following data time slots due to the guard interval.

Comparing Figure 1(b) with Figure 3(b) and Figure 3(c), it can be seen that in the existing random access channel allocation structure of medium coverage and large coverage systems, preamble sequences can only be allocated in tight The location of the GP is close to the location of the GP, and when the uplink channel allocation can be performed, the Preamble sequence structure with a guard interval shown in Figure 2 is used. The specific location of the random access channel is no longer necessarily the first behind the GP. In a time slot, it can be flexibly configured in the uplink channel. In the large coverage system shown in Figure 3(c), in the case of relatively large interference, when TS3 and TS4 are also uplink time slots, the random access preamble sequence can be placed in the positions of TS3 and TS4 time slots. The preamble sequence is placed in the TS3 and TS4 time slots, so that the sending position of the random access preamble sequence is far away from the moment when the TS0 time slot and DwPTS time slot of the remote base station arrive at the cell, thereby avoiding the time slot TS0 and DwPTS of the remote base station. The slot interferes with the preamble sequence of the cell.

Figure 4(a) and Figure 4(c) respectively show the small coverage and large coverage cases, TS4 is the downlink time slot, and the random access preamble sequence position allocation scheme comparison diagram, Figure 4(b) shows the middle In terms of coverage, TS3 is a random access preamble sequence location allocation scheme for downlink time slots. In the case of medium coverage, since TS3 is downlink, the random access preamble sequence can only be allocated in TS1 and TS2 time slots. In the case of large coverage, since TS4 is downlink, random access preamble sequences can only be allocated in TS2 and TS3 time slots. Compared with the scheme without GT, in this random access channel allocation scheme, the preamble sequence will not occupy the time of GP, so the interference of remote base stations TS0 and DwPTS will be small. In practice, this structure is mainly used in cells where the interference between TS0 and DwPTS is not very large.

Using the random access preamble sequence structure with guard interval designed in the present invention, the allocation criterion in the random access channel of the medium coverage and large coverage system is: when there are enough uplink channels, carry out according to the interference situation The allocation of the position of the random access preamble sequence, when the interference is relatively large, allocate the position of the random access preamble sequence and its guard interval as far as possible to the uplink time slot position away from the uplink and downlink guard intervals. In this way, when there are enough uplink time slots, interference from remote base stations can be avoided.

Specifically, the interference of TS0 and DwPTS in a certain cell can be measured when the cell is initially set up, and the random access channel can be allocated according to the measured value. Dynamic measurement is not necessary, and dynamic measurement is also complicated and difficult to measure. .

The length of the random access preamble sequence with guard interval shown in Figure 3 and Figure 4 corresponds to the length of two time slots. In practice, in order to ensure the detection probability, the random access preamble sequence and GT may be longer, that is The length of N slots. Right now

Length(preamble sequence+GT)=N×Length(TS)

Length represents the function to obtain the length of time. For medium coverage, N is an integer greater than or equal to 1, that is, the time length of preamble and GT can be placed in one time slot; for large coverage, N can only be An integer greater than 1, because only one slot for preamble transmission is not enough for large coverage. The meaning of the above formula is that the sum of the duration occupied by the preamble sequence and the GT guard interval is equal to an integer multiple of a time slot in TD-SCDMA.

In the case of relatively strong interference, the allocation criterion of the random access preamble sequence with guard interval in the random access channel described in the present invention is applicable to the random access preamble sequence of any length.

Adopt the following method to produce the long preamble sequence of large-radius sub-district in the specific embodiment of the present invention:

A. Generate long preamble sequences directly. The advantage of this method is that the number of sequences that can be used is large, but the complexity of generating long preamble sequences is relatively high, and it is difficult to implement;

B. Repeat the short preamble sequence to form a long preamble sequence. The advantage of this method is that while providing a sufficient number of sequences, it can avoid the high complexity of directly generating long sequences, and can also improve the detection performance to a certain extent.

For the selection of the specific preamble sequence, you can choose Zadoff-Chu sequence, GCL sequence, Golay sequence, or Barker sequence with good autocorrelation and cross-correlation characteristics.

In a specific embodiment of the present invention, a short Zadoff-Chu sequence is used as a synchronization code sequence, and the short Zadoff-Chu sequence is repeated to form a long preamble sequence in the case of medium coverage and large coverage. In Fig. 5(a), a 521-point Zadoff-Chu sequence is used, its time length is 533.33us, the guard interval time length is 141.67us, and the corresponding cell radius is 21.25km. In Figure 5(b), two 521-point Zadoff-Chu sequences are used, that is, the 521-point Zadoff-Chu sequence is used to repeat once, the time length is 1066.66us, and the guard interval time length is 283.34us, corresponding to the cell radius It is 42.5km. In Figure 5(c), three 521-point Zadoff-Chu sequences are used, that is, the 521-point Zadoff-Chu sequence is used to repeat twice, the time length is 1599.99us, and the guard interval time length is 425.01us, corresponding to the cell The radius is 63.75km. For a larger cell radius, the formula for calculating the number of Zadoff-Chu sequences of 521 points constituting the preamble sequence is:

TRUNC (community radius in kilometers/21.25km)

TRUNC is an upward rounding function. For example, when the cell radius is 84km, 84km/21.25 is about 3.953, which is rounded up to 4, that is, four 521-point Zadoff-Chu sequences are used to form the preamble sequence when covering 84km kilometers . For example, when the cell radius is 85km, 85km/21.25 is 4, then use 4 Zadoff-Chu sequences of 521 points. For example, when the cell radius is 86km, 86km/21.25 is about 4.05, then use five Zadoff-Chu sequences of 521 points, and so on.

Figure 6 is a sequence diagram of the random access process between the UE and the base station. According to the time sequence of signal transmission, the entire random access process can be divided into 4 steps, which are described in detail below:

Step 1: The base station broadcasts the location information of the random access channel and all preamble sequence identifiers available in the cell through the broadcast channel.

Due to the limitation of the length of the random access channel, the number of uplink time slots allocated by the base station is also limited to a certain extent. Different from the prior art, with the technical solution disclosed in the present invention, the number of uplink time slots at this time must meet the requirement of sending random access channel length. For medium coverage, the base station must allocate at least one uplink time slot. If the random access channel occupies the length of two uplink time slots, the base station must allocate at least two uplink time slots; for large coverage, the base station must allocate at least two uplink time slots. Two uplink time slots need to be allocated, otherwise the random access channel cannot be allocated. After allocating the number of uplink time slots according to the length of the random access channel and the amount of uplink data required by the system, the base station allocates the number of random access channels according to the estimated number of random access users in the current cell. Then, the base station broadcasts the location information of the random access channel and the preamble sequence used by the cell through the broadcast channel.

In TD-SCDMA, the number of preamble sequences that can be used in a cell has been planned during the cell planning. If the planned number is 16, the base station of the cell will broadcast all available preamble sequences when broadcasting downwards. The UE chooses randomly by itself.

In a specific embodiment of the present invention, in order to identify the channel transmission quality corresponding to the preamble sequence to the terminal, all available preamble sequences are grouped, such as 16 sequences are divided into two groups, namely group 1 and group 2, then select group 1 sequence, it implies that its downlink channel quality is relatively good; if the selected sequence is in group 2, it implies that its downlink channel quality is relatively poor. In addition to the above-mentioned downlink channel quality, other parameters can also be selected for grouping conditions.

Step 2: Randomly select a preamble sequence from all preamble sequences, and send it to the base station on a random access channel.

The UE randomly selects a preamble sequence from the optional preamble sequence group according to the broadcast information of the base station and the implicit information transmitted by the preamble sequence according to the current need, and then randomly selects a channel among all random access channels, and sends the preamble sequence.

The sending timing advance of this preamble is determined according to the timing advance algorithm. Since the GT is placed behind the preamble, a constant, namely GT/2, needs to be subtracted from the timing advance, so that the preamble will not interfere with the preceding and following data time slots within the range of the random access channel.

Step 3: The base station detects the preamble sequence at the assigned random access channel position. The detection is a correlation detection, and the base station responds to the detected preamble sequence, and the response channel is a fixed channel. The response information of the base station includes the response preamble sequence, timing advance information, etc., and may also include resource allocation information corresponding to the preamble sequence. Of course, the resource allocation information may also be default, that is, not to be sent.

Step 4: The UE detects the response channel of the base station within a fixed period of time, and if it detects the preamble sequence sent by itself, then the UE considers itself detected by the base station. Then, the UE sends data on the uplink resource corresponding to the preamble.

Fig. 7 is a block diagram of the random access part of the terminal and the base station capable of implementing the aforementioned method of the present invention. The composition of the random access part of the terminal includes: a sequence selection module, a random access channel formation module, a sending module, and a base station response detection module. The sequence selection module is used to select and obtain the preamble sequence in the broadcast information of the base station. The random access channel forming module is used to form a random access channel according to the cell broadcast information and the selected preamble sequence. The preamble sequence in the formed random access channel carries its own guard interval, and the preamble sequence and its guard interval are located in the uplink time slot in the TD-SCDMA frame. The sending module is configured to send the preamble sequence to the base station of the cell through a random access channel. The base station response detection module is used to detect the base station response channel to determine whether the access is successful.

The composition of the random access part of the base station includes: a broadcast module, a random access sequence detection module, a random access response module, an uplink time slot setting module, and a preamble sequence grouping module. The broadcast module is used to broadcast the location information of the random access channel and the preamble sequence available in the cell through the broadcast channel. The random access sequence detection module is used to detect the preamble sequence in the random access channel, and the preamble sequence carries its own guard interval. The random access response module is configured to respond to the detected preamble sequence through the response channel. The uplink time slot setting module is used to configure the uplink time slot according to the coverage area and the time slot width occupied by the preamble sequence and the guard interval. The purpose of this module is to make the number of uplink time slots must meet the length of the sending random access channel requirements, the settings can be set during system initialization. The preamble sequence grouping module is configured to group the preamble sequences according to the grouping conditions corresponding to the preamble sequences, such as downlink channel quality. The grouping itself identifies relevant information about the grouping conditions to the client, and the client can perform corresponding operations according to the implicit information contained in the grouping.

The present invention improves the structure of the random access channel, combined with the allocation criterion of the random access channel disclosed in the present invention, it can avoid the interference of the TS0 time slot and the DwPTS time slot of the remote cell on the random access process as much as possible. Therefore, accurate and fast random access of the UE is realized, and the operation efficiency of the entire communication system is improved.

The present invention can also have other various embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations are all Should belong to the scope of protection of the appended claims of the present invention.

Claims (13)

1. A time division duplex random access method, when a mobile user terminal is performing random access, it sends a preamble sequence to the cell through a random access channel, and it is characterized in that a blank is included inside the random access channel An area, as a guard interval of the preamble sequence, wherein the preamble sequence and the guard interval are allocated in uplink time slots away from the uplink and downlink guard intervals, and the guard interval is located in the preamble sequence followed by the preamble sequence. 2. The time division duplex random access method according to claim 1, wherein the value range of the guard interval time length is greater than zero and less than or equal to the time experienced by the speed of light corresponding to 2 times the cell radius distance. 3. The time division duplex random access method according to any one of claims 1 to 2, wherein the random access preamble sequence and its guard interval can span more than two time slots, and its total The duration is obtained as follows: Length (preamble sequence + guard interval) = N*Length(TS) Wherein, Length represents a function for calculating the time length, N is a positive integer greater than or equal to 1 and less than or equal to the sum of the number of uplink time slots, and TS represents a single time slot. 4. The time division duplex random access method according to claim 3, wherein the random access preamble sequence is a directly generated long synchronization code sequence, or is formed by repeating a short synchronization code sequence. 5. The time division duplex random access method according to claim 4, wherein the synchronization code sequence is a Zadoff-Chu sequence, a GCL sequence, a Colay sequence or a Barker sequence. 6. time division duplex random access method according to claim 5, is characterized in that, uses the Zadoff-Chu sequence of 521 points as reference synchronous code sequence, under the larger coverage situation, the Zadoff-Chu sequence of this 521 points The long preamble sequence is formed after the sequence is repeated. 7. The time-division duplex random access method according to claim 6, wherein the number of Zadoff-Chu sequences forming the 521 points of the preamble sequence is rounded up after dividing 21.25 kilometers by the cell radius The resulting integer value. 8. A time division duplex terminal random access module, at least including: A sequence selection module, configured to select and obtain the preamble sequence in the broadcast information of the base station; A random access channel forming module, configured to form a random access channel according to the broadcast information and the selected preamble sequence; A sending module, configured to send a preamble sequence to a cell base station through a random access channel; The base station response detection module is used to detect the base station response channel to determine whether the access is successful; It is characterized in that the random access channel includes a blank area inside as a guard interval of the preamble sequence, and the guard interval of the preamble sequence is located after the preamble sequence and immediately adjacent to the preamble sequence. The synchronization code sequence, the preamble sequence and the guard interval are allocated in the uplink time slot far away from the uplink and downlink guard intervals. 9. The TDD terminal random access module according to claim 8, wherein the random access preamble sequence and its guard interval can span more than two time slots, and its total duration is according to the following method get: Length (preamble sequence + guard interval) = N*Length(TS) Wherein, Length represents a function for calculating the time length, N is a positive integer greater than or equal to 1 and less than or equal to the sum of the number of uplink time slots, and TS represents a single time slot. 10. A time division duplex base station random access module, comprising at least: The broadcast module is used to broadcast the location information of the random access channel and the preamble sequence usable by the cell through the broadcast channel; A random access sequence detection module, configured to detect a preamble sequence in a random access channel; A random access response module, configured to respond to the detected preamble sequence through a response channel; It is characterized in that the random access channel includes a blank area inside as a guard interval of the preamble sequence, and the guard interval of the preamble sequence is located after the preamble sequence, immediately adjacent to the The preamble sequence, the preamble sequence and the guard interval are allocated in uplink time slots away from the uplink and downlink guard intervals. 11. The time division duplex base station random access module according to claim 10, characterized in that, the base station random access module also includes an uplink time slot setting module for Configure the uplink time slot according to the time slot width occupied by the guard interval. 12. The time division duplex base station random access module according to claim 11, further comprising a preamble sequence grouping module for grouping according to the corresponding grouping conditions of each preamble sequence. 13. A time division duplex random access system, comprising a terminal random access module and a base station random access module, the terminal random access module at least including: A sequence selection module, configured to select and obtain the preamble sequence in the broadcast information of the base station; A random access channel forming module, configured to form a random access channel according to the broadcast information and the selected preamble sequence; A sending module, configured to send a preamble sequence to a cell base station through a random access channel; The base station response detection module is used to detect the base station response channel to determine whether the access is successful; The base station random access module includes at least: The broadcast module is used to broadcast the location information of the random access channel and the preamble sequence usable by the cell through the broadcast channel; A random access sequence detection module, configured to detect a preamble sequence in a random access channel; A random access response module, configured to respond to the detected preamble sequence through a response channel; It is characterized in that the random access channel includes a blank area inside as a guard interval of the preamble sequence, and the guard interval of the preamble sequence is located after the preamble sequence and immediately adjacent to the preamble sequence. The synchronization code sequence, the preamble sequence and the guard interval are allocated in the uplink time slot far away from the uplink and downlink guard intervals. the

Images