Communication system
A system is disclosed in which a base station defines a search space, in which a communication device can search for control information. The search space is characterised by at least first information which is related to a starting subframes of a plurality of portions of the search space and second information which is related to a periodicity between respective starting subframes, each portion representing a different candidate for the transmission of control information. The base station obtains a parameter indicating both the initial starting subframe and the periodicity and transmits the generated parameter to the communication device.
1. A base station comprising:
a memory storing instructions; and
at least one processor configured to process the instructions to:
determine a periodicity (T) related to a time period between respective starting subframes for search spaces, and
transmit, to a user equipment (UE), a radio resource control (RRC) message including a parameter indicating a max number of repetition for the search spaces (Rmax) and a parameter representing a factor (G), wherein the periodicity (T) is represented by a mathematical expression:
T=R max* G,
wherein the factor G corresponds to a starting subframe configuration for Physical Downlink Control Channel (PDCCH) user-specific search space.
2. The base station according to claim 1 , wherein the parameter Rmax is given by a higher layer parameter mPDCCH-NumRepetition and the factor G is given by a higher layer parameter mPDCCH-startSF-CSS-RA-r13 or mPDCCH-startSF-UESS.
3. The base station according to claim 1 , wherein the parameter Rmax gives at least one of repetition levels r1, r2, r3 and r4, each level being selected from a set of R {1, 2, 4, 8, 16, 32, 64, 128, 256}.
4. The base station according to claim 3 , wherein relationships among the parameter Rmax and at least one of r1, r2, r3 and r4 are given by the following Table 1 representing determination of repetition levels
TABLE 1
R max
r1
r2
r3
r4
1
1
—
—
—
2
1
2
—
—
4
1
2
4
—
>=8
r max /8
r max /4
r max /2
r max .
5. The base station according to claim 3 , wherein the factor G comprises following types:
a Type0-MPDCCH common search space if configured with modeA,
a Type1-MPDCCH common search space, (CSS),
a Type2-MPDCCH common search space, and
a MPDCCH UE-specific search space.
6. The base station according to claim 5 , wherein relationships among the parameter Rmax and at least one of r1, r2, r3 and r4 are given by the following Table 2 representing determination of repetition levels for Type1-M-PDCCH CSS
TABLE 2
R max
r1
r2
r3
r4
256
2
16
64
256
128
2
16
64
128
64
2
8
32
64
32
1
4
16
32
16
1
4
8
16
8
1
2
4
8.
7. The base station according to claim 1 , wherein the at least one processor is further configured to process the instructions to determine a starting subframe of a search space using a formula:
(10 n f +└n s /2┘)mod T =0
wherein n f corresponds to the system frame number, and n s corresponds to the slot number.
8. A user equipment (UE) configured to communicate with a base station, the UE comprising:
a memory storing instructions; and
at least one processor configured to process the instructions to:
receive, from the base station, a radio resource control (RRC) message including a parameter indicating a max number of repetition for search spaces (Rmax) and a parameter representing a factor (G), wherein aperiodicity (T) is represented by a mathematical expression:
T=R max* G , and
wherein the periodicity (T) is related to a time period between respective starting subframes for the search spaces, and
wherein the factor G corresponds to a starting subframe configuration for Physical Downlink Control Channel (PDCCH) user-specific search space.
9. The UE according to claim 8 , wherein the parameter Rmax is given by a higher layer parameter mPDCCH-NumRepetition and the factor G is given by a higher layer parameter mPDCCH-startSF-CSS-RA-r13 or mPDCCH-startSF-UESS.
10. The UE according to claim 8 , wherein the parameter Rmax gives at least one of repetition levels r1, r2, r3 and r4, each level being selected from a set of R {1, 2, 4, 8, 16, 32, 64, 128, 256}.
11. The UE according to claim 10 , wherein relationships among the parameter Rmax and at least one of r1, r2, r3 and r4 are given by the following Table 3 representing determination of repetition levels
TABLE 3
R max
r1
r2
r3
r4
1
1
—
—
—
2
1
2
—
—
4
1
2
4
—
>=8
r max /8
r max /4
r max /2
r max .
12. The UE according to claim 10 , wherein the factor G comprises following types:
a Type0-MPDCCH common search space if configured with modeA,
a Type1-MPDCCH common search space, (CSS),
a Type2-MPDCCH common search space, and
a MPDCCH UE-specific search space.
13. The UE according to claim 12 , wherein relationships among the parameter Rmax and at least one of r1, r2, r3 and r4 are given by the following Table 4 representing determination of repetition levels for Type1-M-PDCCH CSS
TABLE 4
R max
r1
r2
r3
r4
256
2
16
64
256
128
2
16
64
128
64
2
8
32
64
32
1
4
16
32
16
1
4
8
16
8
1
2
4
8.
14. The UE according to claim 8 , wherein a starting subframe of a search space is determined using a formula:
(10 n f +└n s /2┘)mod T =0
wherein n f corresponds to the system frame number, and ns corresponds to the slot number.
15. The UE according to claim 8 , comprising a narrow bandwidth, low complexity and coverage enhanced machine-type communication, MTC device.
16. A method performed by a base station, the method comprising:
determining a periodicity (T) related to a time period between respective starting subframes for search spaces, and
transmitting, to a user equipment (UE), a radio resource control (RRC) message including a parameter indicating a max number of repetition for the search spaces (Rmax) and a parameter representing a factor (G), wherein the periodicity (T) is represented by a mathematical expression:
T=R max* G,
wherein the factor G corresponds to a starting subframe configuration for Physical Downlink Control Channel (PDCCH) user-specific search space.
17. A method performed by a user equipment (UE), the method comprising:
receiving, from a base station, a radio resource control (RRC) message including a parameter indicating a max number of repetition for search spaces (Rmax) and a parameter representing a factor (G), wherein aperiodicity (T) is represented by a mathematical expression:
T=R max* G , and
wherein the periodicity (T) is related to a time period between respective starting subframes for the search spaces,
wherein the factor G corresponds to a starting subframe configuration for Physical Downlink Control Channel (PDCCH) user-specific search space.