WO2009046668A1

WO2009046668A1 - Method and apparatus for service transmission in the time division duplex system

Info

Publication number: WO2009046668A1
Application number: PCT/CN2008/072537
Authority: WO
Inventors: Shiqiang Suo; Xueming Pan; Hai Tang; Ke Wang; Shaohui Sun; Yingmin Wang
Original assignee: Da Tang Mobile Communications Equipment Co., Ltd.
Priority date: 2007-09-30
Filing date: 2008-09-26
Publication date: 2009-04-16
Also published as: CN101399628A; CN101399628B

Abstract

A method and an apparatus for service transmission in the time division duplex system are provided, at first configuring a couple of uplink and downlink switching points and a group of special slots in a wireless frame, and determining the length of guard period in the group of special slots according to the demand of system to the cover area, and then the system uses configured wireless frame to transmit service. The application of the embodiment of the present invention will not only accommodate the demand of system to the cover area, but also reduce the system overhand, and will enhance the transmission efficiency of system.

Description

Method and device for performing trade in time division duplex system

Technical field

The present invention relates to a Time Division Duplex (TDD) system, and more particularly to a method and apparatus for service transmission in a TDD system. Background of the invention

In a TDD system, the transmission coverage of the system is closely related to the frame structure used for transmission. To meet the requirements of Long Term Evolution (LTE), the frame structure of the TDD system is preferably the second type of frame structure in the two frame structures supported by the LTE system.

When the coverage is large, this frame structure results in a significant reduction in system transmission efficiency and does not really meet the system coverage requirements.

Summary of the invention

In view of this, the main purpose of embodiments of the present invention is to provide a method and apparatus for performing service transmission in a TDD system, which can not only meet the requirements of system coverage, but also improve system transmission efficiency.

Another main object of embodiments of the present invention is to provide an apparatus for performing traffic transmission in a TDD system, which can not only adapt to system coverage requirements, but also improve system transmission efficiency.

In order to achieve the first aspect of the present invention, an embodiment of the present invention provides a method for performing service transmission in a time division duplex system, including the following steps:

A. Configuring a pair of uplink and downlink switching points and a special time slot in a radio frame, a group The special time slot includes a guard interval of downlink to uplink handover, and determines the length of the guard interval according to the requirement of the coverage of the cell;

B. Use the radio frame configured in step A to perform service transmission.

In order to achieve the second aspect of the above object, an embodiment of the present application provides an apparatus for performing traffic transmission in a time division duplex system, the apparatus comprising: a configuration module and a transmission module; and the configuration module configuring a pair in one radio frame An uplink-downlink switching point and a set of special time slots, the special time slot includes a guard interval of downlink to uplink handover, and determines the length of the guard interval according to the cell coverage requirement; the transmission module uses the frame configured by the configuration module Structure for business transmission.

It can be seen from the above technical solution that the method and device for performing service transmission in the time division duplex system provided by the embodiment of the present invention first configure a pair of uplink and downlink switching points and a guard interval (Guard Period, GP), and determine the length of the GP according to the system's coverage requirements, and then the system uses the configured radio frame to transmit the service. In this way, in the embodiment of the present invention, the length of the GP is determined according to the requirements of the coverage of the system, which can meet the requirements of the system coverage, and in the system transmission, one radio frame occupies only one GP overhead, and the prior art The overhead of two GPs is required, so that at least half of the system overhead is reduced relative to the same coverage of the prior art, and the system transmission efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic diagram of a basic second type of frame structure;

2 is a schematic diagram of a frame structure supporting small coverage;

FIG. 3 is a schematic diagram of a frame structure of a supported overlay;

Figure 4 is a schematic diagram of a frame structure supporting large coverage;

FIG. 5 is a schematic diagram of a transmission process of a first embodiment of a transmission method according to the present invention; FIG.

6 is a schematic structural diagram of a first frame configured in the embodiment shown in FIG. 5; 7 is a schematic structural diagram of a second frame configured in the embodiment shown in FIG. 5;

8 is a schematic structural diagram of a third frame configured in the embodiment shown in FIG. 5;

9 is a schematic diagram of a transmission process of a second embodiment of a transmission method according to the present invention;

FIG. 10 is a schematic structural diagram of a transmission apparatus according to an embodiment of the present invention. Mode for carrying out the invention

The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

The basic second type of frame structure is shown in Figure 1: The second type of radio frame has a frame length of 10 ms, and each radio frame is split into two 5 ms fields. Each field consists of 7 service slots and a special set of slots from TS0 ~ TS6 (identified by # 0 ~ # 6 in Figure 1). The special time slot of the group includes three special time slots, namely: an uplink pilot time slot (UpPTS), a guard interval (GP) required for downlink time slot to uplink time slot switching, and a downlink pilot time slot (DwPTS). Each service slot is one subframe, and the service slots TS0 to TS6 correspond to subframe 0 to subframe 6. The subframe 0 and downlink pilot slots are always used for downlink transmission, and the uplink pilot slot and subframe 1 are always used for uplink transmission.

For a TDD system, the duration of the GP is equal to the time elapsed twice the radius of the electromagnetic wave propagation cell, ie T _GP = 2*R _cell /C , where R _cell is the cell radius and C is the speed of light (3*10 ⁸ m/s) Therefore, it can be known that the coverage of each cell is determined by the length of the GP in the radio frame configured by the base station side, that is, the maximum coverage that the system transmission can support is determined by the length of the GP in the configured radio frame. .

By adjusting the length of the GP, you can adapt to the system's coverage requirements, such as the following three cases:

1. In the case where the cell radius is less than 7.5km, the structure supporting the small coverage frame is used, and the GP duration is determined to be 50 us. The frame structure is specifically as shown in FIG. 2: each service time slot is 0.675 ms. The downlink pilot time slot is 83.33us, the GP is 50 us, and the uplink pilot time slot is 141.66 us. At this time, random access is performed in the uplink pilot time slot.

2. For a case where the cell radius is greater than 7.5 km and less than 30 km, the basic second type of frame structure has insufficient GP length, and the GP and UpPTS are combined to form a new GP supporting medium coverage frame structure, and the frame structure is as follows: Figure 3 shows: Each service slot is

0.675ms, the downlink pilot time slot is 83.33us, and the GP time length is 191.66us. At this time, it is just able to support a coverage of about 29 km, and random access is performed in TS1 or any subsequent uplink time slot.

3. For the case where the cell radius is greater than 30 km, the frame structure of the large coverage is formed by vacating the entire TS1 and combining with the GP and UpPTS to form a new GP. The frame structure is as shown in FIG. 4: 0.675ms, the downlink pilot time slot is 83.33us, and the GP time length is 866.66us. At this time, it is sufficient to support cell coverage of 100 km or more, and random access is performed in TS2 and subsequent consecutive uplink time slots.

As shown in FIG. 4, for the second type of frame structure, one radio frame includes two 5ms half frames, and there is a pair of uplink and downlink switching points in each half frame, and two radio pairs are included in one radio frame. Line switching point. Among them, a pair of uplink and downlink switching points refers to a switching point from downlink to uplink and a switching point from uplink to downlink. In Figure 4, the downlink-to-uplink switching point is located at the GP, and the uplink-to-downlink switching point is located between two adjacent subframes of TS3 and TS4.

The inventors of the present invention have found that when supporting large coverage, each field requires a large GP and random access overhead, especially when supporting coverage of more than 30 km, each subframe needs to be associated with TS1 and UpPTS. The GP combines and requires multiple consecutive upstream time slots for random access. In this case, not only the resources of TS1 and UpPTS are occupied, but also the resource overhead exists in every field. When the coverage is large, the transmission efficiency of the system is significantly reduced, and the system coverage cannot be truly adapted. Requirements.

Method for performing service transmission in such time division duplex system provided by embodiment of the present invention The device configures a pair of uplink and downlink switching points and a set of special time slots in a radio frame, and determines the length of the GP in the special time slot according to the requirement of the coverage of the system, and then transmits the service according to the configured radio frame.

In an actual application, the foregoing embodiments of the present invention can implement the foregoing methods and devices by using at least two implementation manners: one is to meet different coverage requirements, and configure a pair of uplink and downlink switching points and a special time slot in a radio frame; Another type can require different logarithmic uplink and downlink switching points and special time slots in the radio frame for different coverage requirements. The following examples are respectively described.

Embodiment 1

This embodiment is a first implementation manner. Referring to FIG. 5, FIG. 5 is a schematic diagram of a transmission process according to a first embodiment of a transmission method according to the present invention. The process includes the following steps:

Step 501: The base station configures a pair of uplink and downlink switching points and a set of special time slots in one radio frame.

For example, the switching point of the downlink to the uplink can be configured at a special time slot. In this embodiment, the switching point can be located at the GP, and the switching point of the uplink to the downlink is configured after the subframe 1 to any two adjacent neighbors at the end of the frame. Between frames. Further, a set of special time slots of the second field may be merged into a set of special time slots of the first field. The subframe 1 referred to here is the first subframe after the guard interval.

Step 502: The base station determines, according to a cell coverage requirement, a length of the GP in the radio frame. The above steps are a process in which the base station configures the frame structure, and a set of special time slots in one radio frame configured according to different coverage requirements may have different configurations. The frame structure of the specific configuration will be described in detail later.

After the base station has configured the frame structure, perform the following steps:

Step 503: The base station notifies the currently adopted frame structure configuration to the user terminal in the cell by using the cell broadcast channel. The notification information mainly includes a current slot structure and uplink and downlink slot allocation information. Step 504: After receiving the frame structure configuration notification, the user terminal performs its own frame structure configuration according to the frame structure in the notification. In this step, the user terminal may perform configuration according to the slot structure in the notification and the uplink and downlink slot allocation information.

The specific steps of the steps 503 and 504 may be: the base station generates the frame structure information according to the configured frame structure, and notifies the frame structure information to the user terminal; the user terminal performs the frame structure configuration according to the notified frame structure information.

Step 505: The base station and the user terminal perform service transmission by using the frame structure configured above. In the frame structure configured in this embodiment, the uplink pilot time slot (UpPTS) may be reserved, and the UpPTS and the GP may be combined to form a new GP. For example: In the case of large coverage, because the random access with UpPTS cannot meet the coverage requirement, other arbitrary uplink time slots such as TS1 are usually used for random access, and even for supporting larger coverage, multiple consecutive uplinks are used. The time slot is randomly accessed. At this time, UpPTS can be used to transmit uplink data, or it can not transfer UpPTS and transfer it to GP.

The following three frame structure configurations are described, all of which configure the uplink and downlink switching points before the first subframe of the second field in the basic second type frame, and are not reserved.

UpPTS.

Referring to FIG. 6, FIG. 6 is a schematic structural diagram of a first frame configured in the embodiment shown in FIG. In a large coverage application, a special time slot including a DwPTS, GP, and UpPTS of a second 5 ms field in each radio frame in the original frame structure may be merged with the GP and UpPTS in the first field to form a GP and an UpPTS. A new GP with a duration of 466.66us, the length of the new GP is equal to the duration of 2*GP+2*UpPTS+DwPTS, and can support a coverage of about 70km. At this time, the random access is performed in multiple consecutive uplink time slots of TS1 and thereafter.

As shown in FIG. 6, the specific configuration of the pair of uplink and downlink switching points of the radio frame is: the downlink to uplink switching point is configured at a special time slot, and the uplink to downlink switching point is disposed between the TS6 and the TS7. In practical applications, the uplink to downlink switching point can be configured after subframe 1 to Between any two adjacent subframes at the end of the frame.

The improved radio frame configured in such a large coverage application is repeated in units of 10ms, and a pair of uplink and downlink switching points are configured within 10ms. Within one 10ms there are: TS0 ~ TS13 a total of 14 service time slots, a set of special time slots containing DwPTS and GP 2 special time slots. The length of the service time slot is still 0.675ms, and the length of the DwPTS is the same as the original frame structure, which is still 83.33us.

When the embodiment of the present invention is applied to an LTE system with Orthogonal Frequency Division Multiplexing (OFDM) as the core technology, for example, it is applied to time division-synchronous code division multiple access using TDD mode ( Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) When the system is long-term evolution, TS1 can be adjusted to further adapt to the system coverage requirements.

Referring to FIG. 7, FIG. 7 is a schematic diagram of a second frame structure configured in the embodiment shown in FIG. For the OFDM system, in order to support a larger coverage, the first n OFDM symbols in the TS1 slot may be vacant for use as a guard interval on the basis of the frame structure shown in FIG. 6, and the TS1 slot is shortened accordingly. . The value range of n is selected according to the cyclic prefix (CP) used in the OFDM subframe. There are two types of CPs that can be selected in an OFDM subframe: one is a short CP, which is a basic option; the other is a long CP, and a long CP can be used for a wide-area cell or multi-cell broadcast. When using short CP, l ≤ n ≤ 9; when using long CP, l ≤ n ≤ 8. For each OFDM symbol in the vacant TS1, the GP length is increased by Tus, and the coverage can be increased by about 11 km, where T is the length of time of one OFDM symbol plus CP. For example, as shown in Fig. 7, the frame structure is hollowed out by the first three OFDM symbols in TS1, which can support a coverage of about 100 km.

When the frame structure configuration shown in FIG. 7 is adopted, in the above step 503, the base station further adds information of how many OFDM symbols are placed in the TS1 in the notification information. In the above step 504, the user terminal further configures its own frame structure according to how many OFDM symbols are placed in the TS1. Referring to FIG. 8, FIG. 8 is a schematic structural diagram of a third frame configured in the embodiment shown in FIG. For the OFDM system, in order to support the coverage of less than 70km, and to save the GP overhead at the same time, on the basis of the frame structure shown in FIG. 6, n OFDM symbols are added before the TS 1 slot, and the TS1 slot corresponds accordingly. increase. Each time an OFDM symbol is added before TS1, the GP length is reduced by Tus, and the coverage is reduced by about 11 km, where T is the length of time of one OFDM symbol plus CP. For example, as shown in FIG. 8, three OFDM symbols are added before the TS 1 in the frame structure, which can support a coverage of about 40 km, and at the same time, the GP overhead is saved to the utmost.

When the frame structure configuration shown in FIG. 8 is used, in the above step 503, the base station further adds information of how many OFDM symbols are added before the TS1 in the notification information. In step 504, the user terminal further configures its own frame structure according to how many OFDM symbols are added before TS1.

Embodiment 2

This embodiment is a second embodiment. Referring to FIG. 9, FIG. 9 is a schematic diagram of a transmission process according to a second embodiment of the present invention, where the process includes the following steps:

Step 901: The base station determines, according to the cell coverage requirement, whether a pair of uplink and downlink switching points or two pairs of uplink and downlink switching points need to be configured in the radio frame. If a pair of uplink and downlink switching points needs to be configured, step 902 is performed, if two For the uplink and downlink switching points, step 904 is performed.

In this embodiment, the system sets three coverage levels according to different coverage requirements in advance: Small coverage level: when the coverage of the base station is less than 7.5 km, it is a small coverage level, and two pairs of uplink and downlink switching points are set in a 10 ms radio frame. , can adopt the frame structure as shown in FIG. 2;

Medium coverage level: When the coverage of the base station is in the range of 7.5km-30km, it is the medium coverage level. Two pairs of uplink and downlink switching points are set in the 10ms radio frame, and the frame structure shown in Figure 3 can be adopted.

Large coverage level: When the coverage is configured to be more than 30km, it is a large coverage level. A pair of uplink and downlink switching points are set in the 10ms radio frame, and a frame structure as shown in FIG. 6 may be adopted. The frame structure may include an UpPTS. In this case, the UpPTS is used for uplink transmission, and the UpPTS may also be classified into the GP. .

The specific coverage size given here is a theoretical estimate. The actual coverage of the system is affected by many factors. The actual coverage may be different from the calculated value. In practical applications, it can be determined according to the actual situation of the system.

In this step, according to the coverage level, according to the coverage level, it is determined according to the coverage level whether a pair of uplink and downlink switching points or two pairs of uplink and downlink switching points need to be configured in the radio frame.

Step 902: The base station configures a pair of uplink and downlink switching points and a set of special time slots in one radio frame.

Step 903: The base station determines the length of the GP in the radio frame according to the cell coverage requirement. Steps 902 to 903 are processes in which the base station configures the frame structure, and a group of special time slots in one radio frame configured according to different coverage requirements may have different configurations. The frame structure of the specific configuration is the same as that of the first embodiment, and will not be repeated here.

After the base station configures the frame structure, step 906 is performed.

Step 904: The base station configures two pairs of uplink and downlink switching points and two sets of special time slots in one radio frame.

Step 905: The base station determines, according to the cell coverage level, the length of the GP in the two sets of special time slots of the radio frame as shown in FIG. 2 (50 us); in the middle coverage level, determining the wireless The length of the GP in the two sets of special time slots of the frame is as shown in Figure 3 (191.66us).

After the base station configures the frame structure, step 906 is performed.

Step 906: The base station notifies the frame structure configuration to the user terminal in the cell by using the cell broadcast channel. Step 907: After receiving the frame structure configuration notification, the user terminal performs its own frame structure configuration according to the frame structure in the notification.

Step 908: The base station and the user terminal perform service transmission by using the frame structure configured above. Further, based on the same inventive concept, an embodiment of the present invention also provides a transmission apparatus corresponding to the above transmission method.

Referring to FIG. 10, FIG. 10 is a schematic structural diagram of a transmission apparatus according to an embodiment of the present invention. The transmission device may be disposed on the base station side, and includes at least: a configuration module 101 and a transmission module 103.

The configuration module 101 is configured to configure a used radio frame structure, configure a pair of uplink and downlink switching points and a set of special time slots in one radio frame, and determine the length of the GP in the radio frame according to the cell coverage requirement. The GP is a guard interval for downlink to uplink switching.

The configuration module 101 in this embodiment may also store three preset coverage levels and corresponding frame structure configurations, for example, may be set as:

Small coverage level: When the coverage of the base station is less than 7.5km, it is a small coverage level, and two pairs of uplink and downlink switching points are set in the 10ms radio frame, and the frame structure as shown in FIG. 2 can be adopted;

Large coverage level: When the coverage is configured to be 30km or more, for a large coverage level, a pair of uplink and downlink switching points are set in a 10ms radio frame, and a frame structure as shown in FIG. 6 may be adopted, and the frame structure may include an UpPTS. In this case, UpPTS is used for uplink transmission, and UpPTS can also be classified into GP.

In this case, the configuration module 101 in this embodiment determines whether to configure one or two pairs of uplink and downlink switching points according to the coverage level when configuring the used radio frame structure, and then determines the length of the GP according to the coverage level.

The transmission module 103 is configured to perform service transmission by using a frame structure configured by the configuration module 101. The configuration module 101 is further configured to generate frame structure information according to the configured frame structure.

The transmitting device may further include a notification module 102, configured to notify the user terminal of the frame structure information generated by the configuration module 101 through the broadcast channel. In the notification information, the frame structure information mainly includes a current slot structure and uplink and downlink slot allocation information. When the frame structure configuration shown in Fig. 7 is adopted, information on how many OFDM symbols are hollowed out by TS1 is further added to the notification information. When the frame structure configuration shown in FIG. 8 is adopted, information of how many OFDM symbols are added before TS1 is further added to the notification information.

The above embodiment is described based on the case where each service slot is one subframe. In actual operation, there is also a case where one subframe includes a plurality of service slots. In this case, if the uplink to downlink switching point is between different subframes, and is independent of the configuration of the time slots in each subframe, in this case, the embodiment of the present invention can be applied without modification. Method and device. If the uplink to downlink switching point is between different time slots of a certain subframe. Only the embodiment of the present invention is modified, and the uplink to downlink switching point is configured between the first time slot of the subframe 1 and any two adjacent time slots at the end of the frame, or configured according to specific requirements of different systems. The switching point of the uplink to the downlink may be used, and the present invention does not specifically limit this. Therefore, although the present invention is described by taking the frame structure of the LTE TDD system as an example, the technical solution disclosed by the present invention can be generally applied to various TDD systems.

It can be seen from the foregoing embodiments that the method and apparatus for performing service transmission in the time division duplex system provided by the embodiments of the present invention can not only meet the requirements of system coverage, but also compare with the prior art in system transmission. The same coverage, at least half the system overhead, improves system transmission efficiency.

The above description is only for the embodiments of the present invention and is not intended to limit the scope of the present invention.

Claims

Claim

A method for performing service transmission in a time division duplex system, characterized in that:

A. Configuring a pair of uplink and downlink switching points and a set of special time slots in a radio frame, where the set of special time slots includes a guard interval of downlink to uplink handover, and determining a length of the guard interval according to a requirement of a cell coverage range. ;

B. Use the radio frame configured in step A to perform service transmission.

The method according to claim 1, further comprising: determining the coverage level according to the coverage requirement before performing step A, and determining the logarithm of the uplink and downlink switching points according to the coverage level, After the row switching point, perform step A.

The method according to claim 2, wherein the determining the number of uplink and downlink switching points according to the coverage level is:

When the coverage of the base station is a small coverage level, two pairs of uplink and downlink switching points are configured in the radio frame; when the coverage of the base station is the medium coverage level, two pairs of uplink and downlink switching points are configured in the radio frame; when the coverage is configured as a large coverage level, the wireless A pair of uplink and downlink switching points are configured in the frame.

The method according to claim 1 or 2, wherein the step A comprises: Al, configuring a pair of uplink and downlink switching points in one radio frame, and determining the protection according to requirements of the base station for cell coverage. The length of the interval, generating frame structure information;

A2, notifying the frame structure information to the user terminal;

A3. The user terminal performs its own frame structure configuration according to the notified frame structure information.

The method according to claim 4, wherein the step A1 configures a pair of uplink and downlink switching points as:

Configuring a downlink-to-uplink switching point at the set of special time slots, and configuring an uplink-to-downlink switching point after the first subframe after the guard interval to any two adjacent subframes at the end of the frame between.

The method of claim 4, wherein one subframe includes a plurality of service time slots, and the pair of uplink and downlink switching points are configured as follows in step A1:

Configuring a downlink to uplink switching point at the set of special time slots, and configuring an uplink to downlink switching point after the first service time slot of the first subframe after the guard interval to the end of the frame Between any two adjacent service slots.

7. The method according to claim 5, wherein a radio frame includes two fields, each of the sub-frames respectively includes the set of special time slots, and the set of special time slots further includes one a downlink pilot time slot and an uplink pilot time slot;

The configuring a pair of uplink and downlink switching points further includes:

The uplink pilot time slot, the guard interval, and the downlink pilot time slot in a set of special time slots of the second field are all combined into a guard interval of a group of special time slots of the first field.

8. The method according to claim 7, wherein the requirement of the coverage range in step A1 determines the length of the guard interval as:

Determining, according to the coverage requirement, the length of the guard interval of the set of special time slots of the merged first field to the length of the guard interval of the configured radio frame;

Or further combining the uplink pilot time slot of the first field with the guard interval of the group of special time slots of the merged first field, and determining the length of the merged guard interval to be the guard interval of the configured radio frame. length.

The method according to claim 8, wherein the frame structure information of step A1 comprises: a slot structure of the currently configured frame structure and uplink and downlink slot allocation information.

The method according to claim 8, wherein when the radio frame is an OFDM frame, the first n OFDM symbols of the first subframe after the guard interval are further vacant according to the coverage requirement. Or adding n OFDM symbols before the first subframe after the guard interval;

Wherein, when the OFDM frame adopts a short cyclic prefix, l≤n≤9; adopted in the OFDM frame When the cyclic prefix is long, l≤n≤8.

The method according to claim 10, wherein the frame structure information of step A1 includes: a slot structure of the currently configured frame structure, and uplink and downlink slot allocation information, and the first one after the guard interval. The subframe information of the OFDM symbol is hollow or the number of OFDM symbols is added before the first subframe after the guard interval.

12. A device for performing service transmission in a time division duplex system, comprising: a configuration module and a transmission module;

The configuration module configures a pair of uplink and downlink switching points and a set of special time slots in a radio frame, where the set of special time slots includes a guard interval of downlink to uplink handover, and determines the coverage according to the cell coverage requirement. The length of the guard interval;

The transmission module uses the frame structure configured by the configuration module to perform service transmission with the user terminal.

The apparatus according to claim 12, wherein the configuration module is further configured to generate frame structure information according to the configured frame structure;

The device further includes:

The notification module notifies the user terminal of the frame structure information generated by the configuration module.

The device according to claim 12 or 13, wherein the configuration module further determines whether to configure one or two pairs of uplink and downlink switching points according to the coverage level when configuring the radio frame structure, and then according to the coverage level. Determine the length of the guard interval.