Method and apparatus for data transmission in a time division duplexing system

1. A method for data transmission in a Time Division Duplexing (TDD) system, comprising:

configuring, by a base station, a length respectively for a Downlink Pilot Slot (DwPTS) and an Uplink Pilot Slot (UpPTS) within a special field of a radio half-frame based on a current coverage area taking one Orthogonal Frequency Division Multiplexing (OFDM) symbol as a unit, and issuing a configured result to a user device; calculating a Guard Period (GP) length required for switching from downlink to uplink based on the coverage area, and configuring a length of a GP slot to occupy N OFDM symbols, wherein the GP length calculated is shorter than N OFDM symbols but longer than N−1 OFDM symbols, N is an integer greater than 1, wherein a total length of the DwPTS, the GP slot and the UpPTS is kept to be 1 ms;

constructing, by the base station, radio half-frames for data transmission according to the configured result.

2. The method of claim 1 , further comprising:

establishing, according to different coverage areas of the base station and different compatibility requirements with a TD-SCDMA system, a relationship between each coverage area and compatibility requirement and lengths of the GP slot, the DwPTS and the UpPTS in advance and storing all relationships in the base station;

wherein the configuring the length respectively for the DwPTS and the UpPTS comprises: determining, by the base station, a length respectively for the GP slot, the DwPTS and the UpPTS corresponding to a current coverage area and compatibility requirement according to the relationships stored.

3. The method of claim 2 , further comprising:

after establishing the relationships, assigning, in the base station, a number for each combination of lengths of the GP slot, the DwPTS and the UpPTS, and

storing, by the user device, different combinations of lengths of the GP slot, the DwPTS and the UpPTS, and assigning a number for each combination in the user device;

wherein the issuing the configured result to the user device comprises: issuing, by the base station, a number corresponding to the combination of lengths determined for the GP slot, the DwPTS and the UpPTS to the user device.

4. The method of claim 2 , wherein the relationships established between the coverage area and compatibility requirement and the lengths of the GP slot, the DwPTS and the UpPTS comprises:

if it is required to be compatible with the TD-SCDMA system, calculating, according to a structure of regular slots of the radio half-frame, the lengths of the GP slot, the DwPTS and the UpPTS corresponding to different downlink-to-uplink slot ratios of the TD-SCDMA system and different coverage areas of the base station; and

if it is not required to be compatible with the TD-SCDMA system, calculating, according to the structure of regular slots of the radio half-frame, the lengths of the GP slot, the DwPTS and the UpPTS corresponding to different coverage areas of the base station.

5. The method of claim 4 , wherein the calculating the lengths of the GP slot, the DwPTS and the UpPTS corresponding to different downlink-to-uplink slot ratios of the TD-SCDMA system and different coverage areas of the base station comprises:

with respect to different Cyclic Prefix (CP) types, establishing a relationship between each downlink-to-uplink slot ratio of the TD-SCDMA system and the lengths of the GP slot, the DwPTS and the UpPTS under a minimum coverage area of the base station; and

as to each coverage area requirement other than the minimum coverage area requirement, extending the length of the GP slot based on the relationship established under the minimum coverage area of the base station, and establishing a relationship between the coverage area requirement and the downlink-to-uplink slot ratio and the lengths of the GP slot, the DwPTS and the UpPTS.

6. The method of claim 2 , further comprising:

before storing the relationships, dividing the relationships into subsets according to downlink-to-uplink slot ratios of the TD-SCDMA system, assigning a number for each subset, and assigning a number for each combination of lengths of the GP slot, the DwPTS and the UpPTS in each subset;

wherein the relationships are stored by the subsets, and the method further comprises: storing, in the user device, the number corresponding to each combination of lengths of the GP slot, the DwPTS and the UpPTS by the subsets.

7. The method of claim 6 , wherein the issuing the configured result to the user device comprises: issuing a subset number and a configuration number of the lengths determined for the GP slot, the DwPTS and the UpPTS to the user device.

8. The method of claim 6 , wherein the issuing the configured result to the user device comprises: issuing a configuration number of the lengths determined for the GP slot, the DwPTS and the UpPTS to the user device.

9. The method of claim 4 , wherein the structure of the regular slots comprises: a radio half-frame comprising 8 regular slots each of which has a length of 0.5 ms and two regular slots form a subframe;

if normal CP is adopted, the relationships between the downlink-to-uplink slot ratios and the lengths of the GP slot, the DwPTS and the UpPTS under the minimum coverage area of the base station comprise:

Downlink-to-

uplink ratios of

Length

Length

Length

the TD-SCDMA

of the

of the

of the

system

DwPTS

GP slot

UpPTS

1:6

10 symbols

2 symbols

2 symbols

4:3

10 symbols

2 symbols

2 symbols

if extended CP is adopted, the relationships established between the downlink-to-uplink slot ratios and the lengths of the GP slot, the DwPTS and the UpPTS under the minimum coverage area of the base station comprise:

Downlink-to-uplink

ratios of the TD-

Length of the

Length of the GP

Length of the

SCDMA system

DwPTS

slot

UpPTS

1:6

8 symbols

2 symbols

2 symbols

4:3

9 symbols

1 symbol 

2 symbols

10. The method of claim 4 , wherein the structure of the regular slots comprises: a radio half-frame comprising 8 regular slots each of which has a length of 0.5 ms and two regular slots form a subframe;

if normal CP is adopted, the relationships between different coverage area and compatibility requirements and the lengths of the GP slot, the DwPTS and the UpPTS comprise:

Length of

Length

Coverage

Compatibility

Length of the

the GP

of the

area

requirement

DwPTS

slot

UpPTS

≦10.7 km

Not compatible

11 symbols

1 symbol 

2 symbols

≦21.4 km

Compatible with

10 symbols

2 symbols

2 symbols

downlink-to-uplink

slot ratio 4:3 and

1:6 or not

compatible

≦32.1 km

Compatible with

 9 symbols

3 symbols

2 symbols

downlink-to-uplink

slot ratio 4:3 and

1:6 or not

compatible

if extended CP is adopted, the relationships between different coverage area and compatibility requirements and the lengths of the GP slot, the DwPTS and the UpPTS comprise:

Length

Length

Coverage

Compatibility

of the

Length of the

of the

area

requirement

DwPTS

GP slot

UpPTS

≦12.4 km

Compatible with

9 symbols

1 symbol 

2 symbols

downlink-to-uplink

slot ratio 4:3 or not

compatible

≦24.8 km

Compatible with

8 symbols

2 symbols

2 symbols

downlink-to-uplink

slot ratio 4:3 and

1:6 or not

compatible

11. The method of claim 1 , further comprising:

respectively configuring a set of configurations for the special field with respect to a situation where it is required to be compatible with a TD-SCDMA system and a situation where it is not required to be compatible with the TD-SCDMA system, wherein each configuration comprises: a length of a GP slot, a length of the DwPTS and a length of the UpPTS which are configured taking each symbol as a unit;

wherein the configuring the lengths for the DwPTS and the UpPTS within the special field of the radio half-frame based on the current coverage area comprises:

determining, by the base station, a set of configurations according to a current situation that whether it is required to be compatible with the TD-SCDMA system; and selecting a configuration from the set of configurations determined according to a current coverage area and system performance requirement.

12. The method of claim 11 , wherein the structure of the regular slots in the radio half-frame is: the radio half-frame comprising 8 regular slots each of which has a length of 0.5 ms and two regular slots form a subframe;

if normal CP is adopted, with respect to the situation where it is not required to be compatible with the TD-SCDMA system, the set of configurations comprises:

Length of the DwPTS

Length of the GP slot

Length of the UpPTS

11

1

2

10

2

2

9

3

2

3

9

2

if extended CP is adopted, with respect to the situation where it is not required to be compatible with the TD-SCDMA system, the set of configurations comprises:

Length of the DwPTS

Length of the GP slot

Length of the UpPTS

9

1

2

8

2

2

3

7

2

wherein the lengths of the DwPTS, the GP slot and the UpPTS take one symbol as a unit.

13. The method of claim 11 , wherein each set of configurations is configured further based on a restriction to the length of the GP slot.

14. The method of claim 11 , wherein the configuring the set of configurations for the situation where it is required to be compatible with the TD-SCDMA system comprises: configuring the set of configurations according to different downlink-to-uplink slot ratios of the TD-SCDMA system and different coverage area requirements.

15. The method of 14 , wherein it is required to be compatible with TD-SCDMA system whose GP slot has a length of 75 us, the set of configurations under a minimum coverage area requirement comprises:

if normal CP is adopted:

Downlink-to-uplink

ratios of the TD-

Length of the

Length of the GP

Length of the

SCDMA system

DwPTS

slot

UpPTS

4:3

10

2

2

if extended CP is adopted:

Downlink-to-uplink

ratios of the TD-

Length of

Length of

Length of

SCDMA system

DwPTS

GP slot

UpPTS

4:3

9

1

2

wherein the lengths of the DwPTS, the GP slot and the UpPTS take the symbol as a unit.

16. The method of claim 14 , wherein each set of configurations is further configured based on a restriction to the length of the GP slot.

17. The method of claim 11 , further comprising: after establishing the sets of configurations, respectively assigning numbers for the configurations in each set which is configured with respect to the situation where it is required to be compatible with the TD-SCDMA system or the situation where it is not required to be compatible with the TD-SCDMA system, and storing relationships between the configurations and numbers in the base station and the user device;

wherein the base station issuing the configuration selected to the user device comprises: informing, by the base station, the user device of whether it is required to be compatible with the TD-SCDMA system, and issuing a number corresponding to the configuration selected to the user device;

wherein the user device constructing the radio half-frame according to the configuration selected comprises: determining, by the user device, the set of configurations according to the information about whether it is required to be compatible with the TD-SCDMA system, determining among the set of configurations the configuration selected by the base station according to the number received, and constructing the radio half-frames according to the configuration.

18. An apparatus for data transmission in a Time Division Duplexing (TDD) system, comprising:

means for respectively setting, within a special field of a radio half-frame and according to a coverage area, a length for a Downlink Pilot Slot (DwPTS) and an Uplink Pilot Slot (UpPTS) taking one Orthogonal Frequency Division Multiplexing (OFDM) symbol as a unit, calculating a Guard Period (GP) length required for switching from downlink to uplink based on the coverage area, and configuring a length of a GP slot to occupy N OFDM symbols, wherein the GP length calculated is shorter than N OFDM symbols but longer than N−1 OFDM symbols, N is an integer greater than 1, issuing a configured result to a user device; and constructing radio half-frames for data transmission according to the configured result, wherein a total length of the DwPTS, the GP slot and the UpPTS is kept to be 1 ms.

19. The apparatus of claim 18 , further comprising:

a relationship storing unit, adapted to establish a relationship between each coverage area and compatibility requirement with a TD-SCDMA system and lengths of the GP slot, the DwPTS and the UpPTS, and store all relationships;

a selecting unit, adapted to select a combination of lengths of the GP slot, the DwPTS and the UpPTS from the relationships stored in the relationship storing unit according to a current coverage area and compatibility requirement.

20. An apparatus for data transmission in a Time Division Duplexing (TDD) system, comprising:

means for configuring a set of configurations for a special field with respect to a situation where it is required to be compatible with a TD-SCDMA system and configure a set of configurations for the special field with respect to a situation where it is not required to be compatible with the TD-SCDMA system, wherein each configuration comprises lengths of a Guard Period (GP) slot, a Downlink Pilot Slot (DwPTS) and an Uplink Pilot Slot (UpPTS) which are configured taking one Orthogonal Frequency Division Multiplexing (OFDM) symbol as a unit, and a total length of the DwPTS, the GP slot and the UpPTS is kept to be 1 ms;

means for determining one set of configurations according to a current situation that whether it is required to be compatible with the TD-SCDMA system; and

means for selecting a configuration from the set of configurations determined according to a coverage area and system performance, issue the configuration selected to a user device; and construct radio half-frames for performing data transmission according to the selected configuration.