Wireless terminal, wireless base station, and transmission method of buffer status report

1. A wireless terminal comprising:

a memory configured to store uplink data; and

a controller configured to:

select an index from among a plurality of indices included in a buffer status table according to the uplink data stored in the memory, and

transmit a buffer status report including the index,

wherein the plurality of indices in the buffer status table includes a first index and a second index, the first index being one of the plurality of indices and being different in index value from any other index in the buffer status table, the first index indicating a 0 byte as a buffer size, the second index being one of the plurality of indices except for the first index and being different in index value from any other index in the buffer status table, the second index indicating Reserve as the buffer size.

2. The wireless terminal according to claim 1 , wherein the buffer size corresponds to a size of the uplink data stored in memory.

3. The wireless terminal according to claim 1 , wherein the memory includes a buffer for storing the uplink data.

4. The wireless terminal according to claim 1 , wherein the buffer size corresponds to a size of the uplink data stored in buffer.

5. The wireless terminal according to claim 1 , wherein the controller selects index from a plurality of indices without the second index.

6. The wireless terminal according to claim 1 , wherein the memory stores the buffer status table in which a range from a minimum value of the buffer to a maximum value of the buffer is divided into a plurality of subranges, the plurality of subranges being associated with a part of the plurality of indices.

7. The wireless terminal according to claim 1 , wherein the controller transmits the buffer status report at predetermined period.

8. The wireless terminal according to claim 1 ,

wherein a range of the plurality of indices is from 0 to 255,

wherein the first index is 0.

9. The wireless terminal according to claim 8 , wherein the buffer status report includes a field which stores the index, the field being defined with a length of 8 bits.

10. The wireless terminal according to claim 8 ,

wherein the buffer status table includes at least pairs defined as follows:

a pair of an index [1] and a subrange [0 byte<BS≤10 bytes];

a pair of an index [2] and a subrange [10 bytes<BS≤11 bytes];

a pair of an index [3] and a subrange [11 bytes<BS≤12 bytes];

a pair of an index [4] and a subrange [12 bytes<BS≤13 bytes];

a pair of an index [5] and a subrange [13 bytes<BS≤14 bytes];

a pair of an index [6] and a subrange [14 bytes<BS≤15 bytes];

a pair of an index [7] and a subrange [15 bytes<BS≤16 bytes];

a pair of an index [8] and a subrange [16 bytes<BS≤17 bytes];

a pair of an index [9] and a subrange [17 bytes<BS≤18 bytes];

a pair of an index [10] and a subrange [18 bytes<BS≤19 bytes];

a pair of an index [11] and a subrange [19 bytes<BS≤20 bytes];

a pair of an index [12] and a subrange [20 bytes<BS≤22 bytes];

a pair of an index [13] and a subrange [22 bytes<BS≤23 bytes];

a pair of an index [14] and a subrange [23 bytes<BS≤25 bytes];

a pair of an index [15] and a subrange [25 bytes<BS≤26 bytes];

a pair of an index [16] and a subrange [26 bytes<BS≤28 bytes];

a pair of an index [17] and a subrange [28 bytes<BS≤30 bytes];

a pair of an index [18] and a subrange [30 bytes<BS≤32 bytes]; and

a pair of an index [19] and a subrange [32 bytes<BS≤34 bytes].

11. The wireless terminal according to of claim 8 , wherein the controller is further configured to:

select, based on a logical channel group of a processing target, either one of the buffer status table or another buffer status table, and

select the index from the selected table,

wherein the another buffer status table has a content such that a range from another minimum value of the buffer size to another maximum value of the buffer size is divided into a plurality of another subranges, the plurality of another subranges being associated with a plurality of another buffer status indices in the another predetermined buffer status table,

wherein the another minimum value of the buffer size in the another buffer status table is 0 bytes.

12. The wireless terminal according to claim 11 , wherein the another buffer status table is assigned to a logical channel group used in a transmission service having large transmission capacity, and the buffer status table is assigned to another logical channel group used in another transmission service having transmission capacity smaller than that of the transmission service.

13. A wireless base station comprising:

a memory; and

a communicator configured to receive from a terminal a buffer status report including an index, the index is selected from among a plurality of indices included in a buffer status table according to uplink data stored in the terminal; and

a controller configured to allocate a resource after receiving buffer status report, wherein

the communicator transmits to the terminal an uplink grant indicating the resource, and

the plurality of indices includes a first index and a second index, the first index being one of the plurality of indices and being different in index value from any other index in the buffer status table, the first index indicating a 0 byte as a buffer size, the second index being one of the plurality of indices except for the first index and being different in index value from any other index in the buffer status table, the second index indicating Reserve as the buffer size.

14. The wireless base station according to claim 13 , wherein the buffer size corresponds to a size of the uplink data stored in the terminal.

15. The wireless base station according to claim 13 , further comprising:

a memory configured to store the buffer status table.

16. The wireless base station according to claim 15 , wherein

the controller is further configured to:

estimate the size of the uplink data based on the index included in the buffer status report and the buffer status table stored in memory, and

allocate the resource according to the estimated size of the uplink data.

17. The wireless base station according to claim 13 ,

wherein a range of the plurality of indices is from 0 to 255,

wherein the first index is 0.

18. The wireless base station according to claim 17 , wherein the buffer status report includes a field which stores the index, the field being defined with a length of 8 bits.

19. The wireless base station according to claim 17 ,

wherein the buffer status table includes at least pairs defined as follows:

a pair of an index [1] and a subrange [0 byte<BS≤10 bytes];

a pair of an index [2] and a subrange [10 bytes<BS≤11 bytes];

a pair of an index [3] and a subrange [11 bytes<BS≤12 bytes];

a pair of an index [4] and a subrange [12 bytes<BS≤13 bytes];

a pair of an index [5] and a subrange [13 bytes<BS≤14 bytes];

a pair of an index [6] and a subrange [14 bytes<BS≤15 bytes];

a pair of an index [7] and a subrange [15 bytes<BS≤16 bytes];

a pair of an index [8] and a subrange [16 bytes<BS≤17 bytes];

a pair of an index [9] and a subrange [17 bytes<BS≤18 bytes];

a pair of an index [10] and a subrange [18 bytes<BS≤19 bytes];

a pair of an index [11] and a subrange [19 bytes<BS≤20 bytes];

a pair of an index [12] and a subrange [20 bytes<BS≤22 bytes];

a pair of an index [13] and a subrange [22 bytes<BS≤23 bytes];

a pair of an index [14] and a subrange [23 bytes<BS≤25 bytes];

a pair of an index [15] and a subrange [25 bytes<BS≤26 bytes];

a pair of an index [16] and a subrange [26 bytes<BS≤28 bytes];

a pair of an index [17] and a subrange [28 bytes<BS≤30 bytes];

a pair of an index [18] and a subrange [30 bytes<BS≤32 bytes]; and

a pair of an index [19] and a subrange [32 bytes<BS≤34 bytes].

20. A wireless communication system comprising:

a terminal configured to:

store uplink data,

select an index from among a plurality of indices included in a buffer status table according to the stored uplink data, and

transmit a buffer status report including the index; and

a base station configured to receive from the terminal the buffer status report,

wherein the plurality of indices in the buffer status table includes a first index and a second index, the first index being one of the plurality of indices and being different in index value from any other index in the buffer status table, the first index indicating a 0 byte as a buffer size, the second index being one of the plurality of indices except for the first index and being different in index value from any other index in the buffer status table, the second index indicating Reserve as the buffer size.